diff --git a/AK/DeprecatedString.cpp b/AK/ByteString.cpp
similarity index 63%
rename from AK/DeprecatedString.cpp
rename to AK/ByteString.cpp
index 408243d430b..a1211261768 100644
--- a/AK/DeprecatedString.cpp
+++ b/AK/ByteString.cpp
@@ -5,8 +5,8 @@
  */
 
 #include <AK/ByteBuffer.h>
+#include <AK/ByteString.h>
 #include <AK/DeprecatedFlyString.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <AK/Function.h>
 #include <AK/StdLibExtras.h>
@@ -16,17 +16,17 @@
 
 namespace AK {
 
-bool DeprecatedString::operator==(DeprecatedFlyString const& fly_string) const
+bool ByteString::operator==(DeprecatedFlyString const& fly_string) const
 {
     return m_impl == fly_string.impl() || view() == fly_string.view();
 }
 
-bool DeprecatedString::operator==(DeprecatedString const& other) const
+bool ByteString::operator==(ByteString const& other) const
 {
     return m_impl == other.impl() || view() == other.view();
 }
 
-bool DeprecatedString::operator==(StringView other) const
+bool ByteString::operator==(StringView other) const
 {
     if (other.is_null())
         return is_empty();
@@ -34,17 +34,17 @@ bool DeprecatedString::operator==(StringView other) const
     return view() == other;
 }
 
-bool DeprecatedString::operator<(DeprecatedString const& other) const
+bool ByteString::operator<(ByteString const& other) const
 {
     return view() < other.view();
 }
 
-bool DeprecatedString::operator>(DeprecatedString const& other) const
+bool ByteString::operator>(ByteString const& other) const
 {
     return view() > other.view();
 }
 
-bool DeprecatedString::copy_characters_to_buffer(char* buffer, size_t buffer_size) const
+bool ByteString::copy_characters_to_buffer(char* buffer, size_t buffer_size) const
 {
     // We must fit at least the NUL-terminator.
     VERIFY(buffer_size > 0);
@@ -56,55 +56,55 @@ bool DeprecatedString::copy_characters_to_buffer(char* buffer, size_t buffer_siz
     return characters_to_copy == length();
 }
 
-DeprecatedString DeprecatedString::isolated_copy() const
+ByteString ByteString::isolated_copy() const
 {
     if (m_impl->length() == 0)
         return empty();
     char* buffer;
     auto impl = StringImpl::create_uninitialized(length(), buffer);
     memcpy(buffer, m_impl->characters(), m_impl->length());
-    return DeprecatedString(move(*impl));
+    return ByteString(move(*impl));
 }
 
-DeprecatedString DeprecatedString::substring(size_t start, size_t length) const
+ByteString ByteString::substring(size_t start, size_t length) const
 {
     if (!length)
-        return DeprecatedString::empty();
+        return ByteString::empty();
     VERIFY(!Checked<size_t>::addition_would_overflow(start, length));
     VERIFY(start + length <= m_impl->length());
     return { characters() + start, length };
 }
 
-DeprecatedString DeprecatedString::substring(size_t start) const
+ByteString ByteString::substring(size_t start) const
 {
     VERIFY(start <= length());
     return { characters() + start, length() - start };
 }
 
-StringView DeprecatedString::substring_view(size_t start, size_t length) const
+StringView ByteString::substring_view(size_t start, size_t length) const
 {
     VERIFY(!Checked<size_t>::addition_would_overflow(start, length));
     VERIFY(start + length <= m_impl->length());
     return { characters() + start, length };
 }
 
-StringView DeprecatedString::substring_view(size_t start) const
+StringView ByteString::substring_view(size_t start) const
 {
     VERIFY(start <= length());
     return { characters() + start, length() - start };
 }
 
-Vector<DeprecatedString> DeprecatedString::split(char separator, SplitBehavior split_behavior) const
+Vector<ByteString> ByteString::split(char separator, SplitBehavior split_behavior) const
 {
     return split_limit(separator, 0, split_behavior);
 }
 
-Vector<DeprecatedString> DeprecatedString::split_limit(char separator, size_t limit, SplitBehavior split_behavior) const
+Vector<ByteString> ByteString::split_limit(char separator, size_t limit, SplitBehavior split_behavior) const
 {
     if (is_empty())
         return {};
 
-    Vector<DeprecatedString> v;
+    Vector<ByteString> v;
     size_t substart = 0;
     bool keep_empty = has_flag(split_behavior, SplitBehavior::KeepEmpty);
     bool keep_separator = has_flag(split_behavior, SplitBehavior::KeepTrailingSeparator);
@@ -123,7 +123,7 @@ Vector<DeprecatedString> DeprecatedString::split_limit(char separator, size_t li
     return v;
 }
 
-Vector<StringView> DeprecatedString::split_view(Function<bool(char)> separator, SplitBehavior split_behavior) const
+Vector<StringView> ByteString::split_view(Function<bool(char)> separator, SplitBehavior split_behavior) const
 {
     if (is_empty())
         return {};
@@ -147,78 +147,78 @@ Vector<StringView> DeprecatedString::split_view(Function<bool(char)> separator,
     return v;
 }
 
-Vector<StringView> DeprecatedString::split_view(char const separator, SplitBehavior split_behavior) const
+Vector<StringView> ByteString::split_view(char const separator, SplitBehavior split_behavior) const
 {
     return split_view([separator](char ch) { return ch == separator; }, split_behavior);
 }
 
-ByteBuffer DeprecatedString::to_byte_buffer() const
+ByteBuffer ByteString::to_byte_buffer() const
 {
     // FIXME: Handle OOM failure.
     return ByteBuffer::copy(bytes()).release_value_but_fixme_should_propagate_errors();
 }
 
 template<typename T>
-Optional<T> DeprecatedString::to_int(TrimWhitespace trim_whitespace) const
+Optional<T> ByteString::to_int(TrimWhitespace trim_whitespace) const
 {
     return StringUtils::convert_to_int<T>(view(), trim_whitespace);
 }
 
-template Optional<i8> DeprecatedString::to_int(TrimWhitespace) const;
-template Optional<i16> DeprecatedString::to_int(TrimWhitespace) const;
-template Optional<i32> DeprecatedString::to_int(TrimWhitespace) const;
-template Optional<long> DeprecatedString::to_int(TrimWhitespace) const;
-template Optional<long long> DeprecatedString::to_int(TrimWhitespace) const;
+template Optional<i8> ByteString::to_int(TrimWhitespace) const;
+template Optional<i16> ByteString::to_int(TrimWhitespace) const;
+template Optional<i32> ByteString::to_int(TrimWhitespace) const;
+template Optional<long> ByteString::to_int(TrimWhitespace) const;
+template Optional<long long> ByteString::to_int(TrimWhitespace) const;
 
 template<typename T>
-Optional<T> DeprecatedString::to_uint(TrimWhitespace trim_whitespace) const
+Optional<T> ByteString::to_uint(TrimWhitespace trim_whitespace) const
 {
     return StringUtils::convert_to_uint<T>(view(), trim_whitespace);
 }
 
-template Optional<u8> DeprecatedString::to_uint(TrimWhitespace) const;
-template Optional<u16> DeprecatedString::to_uint(TrimWhitespace) const;
-template Optional<u32> DeprecatedString::to_uint(TrimWhitespace) const;
-template Optional<unsigned long> DeprecatedString::to_uint(TrimWhitespace) const;
-template Optional<unsigned long long> DeprecatedString::to_uint(TrimWhitespace) const;
+template Optional<u8> ByteString::to_uint(TrimWhitespace) const;
+template Optional<u16> ByteString::to_uint(TrimWhitespace) const;
+template Optional<u32> ByteString::to_uint(TrimWhitespace) const;
+template Optional<unsigned long> ByteString::to_uint(TrimWhitespace) const;
+template Optional<unsigned long long> ByteString::to_uint(TrimWhitespace) const;
 
 #ifndef KERNEL
-Optional<double> DeprecatedString::to_double(TrimWhitespace trim_whitespace) const
+Optional<double> ByteString::to_double(TrimWhitespace trim_whitespace) const
 {
     return StringUtils::convert_to_floating_point<double>(*this, trim_whitespace);
 }
 
-Optional<float> DeprecatedString::to_float(TrimWhitespace trim_whitespace) const
+Optional<float> ByteString::to_float(TrimWhitespace trim_whitespace) const
 {
     return StringUtils::convert_to_floating_point<float>(*this, trim_whitespace);
 }
 #endif
 
-bool DeprecatedString::starts_with(StringView str, CaseSensitivity case_sensitivity) const
+bool ByteString::starts_with(StringView str, CaseSensitivity case_sensitivity) const
 {
     return StringUtils::starts_with(*this, str, case_sensitivity);
 }
 
-bool DeprecatedString::starts_with(char ch) const
+bool ByteString::starts_with(char ch) const
 {
     if (is_empty())
         return false;
     return characters()[0] == ch;
 }
 
-bool DeprecatedString::ends_with(StringView str, CaseSensitivity case_sensitivity) const
+bool ByteString::ends_with(StringView str, CaseSensitivity case_sensitivity) const
 {
     return StringUtils::ends_with(*this, str, case_sensitivity);
 }
 
-bool DeprecatedString::ends_with(char ch) const
+bool ByteString::ends_with(char ch) const
 {
     if (is_empty())
         return false;
     return characters()[length() - 1] == ch;
 }
 
-DeprecatedString DeprecatedString::repeated(char ch, size_t count)
+ByteString ByteString::repeated(char ch, size_t count)
 {
     if (!count)
         return empty();
@@ -228,7 +228,7 @@ DeprecatedString DeprecatedString::repeated(char ch, size_t count)
     return *impl;
 }
 
-DeprecatedString DeprecatedString::repeated(StringView string, size_t count)
+ByteString ByteString::repeated(StringView string, size_t count)
 {
     if (!count || string.is_empty())
         return empty();
@@ -239,7 +239,7 @@ DeprecatedString DeprecatedString::repeated(StringView string, size_t count)
     return *impl;
 }
 
-DeprecatedString DeprecatedString::bijective_base_from(size_t value, unsigned base, StringView map)
+ByteString ByteString::bijective_base_from(size_t value, unsigned base, StringView map)
 {
     value++;
     if (map.is_null())
@@ -265,13 +265,13 @@ DeprecatedString DeprecatedString::bijective_base_from(size_t value, unsigned ba
     for (size_t j = 0; j < i / 2; ++j)
         swap(buffer[j], buffer[i - j - 1]);
 
-    return DeprecatedString { ReadonlyBytes(buffer.data(), i) };
+    return ByteString { ReadonlyBytes(buffer.data(), i) };
 }
 
-DeprecatedString DeprecatedString::roman_number_from(size_t value)
+ByteString ByteString::roman_number_from(size_t value)
 {
     if (value > 3999)
-        return DeprecatedString::number(value);
+        return ByteString::number(value);
 
     StringBuilder builder;
 
@@ -318,44 +318,44 @@ DeprecatedString DeprecatedString::roman_number_from(size_t value)
         }
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-bool DeprecatedString::matches(StringView mask, Vector<MaskSpan>& mask_spans, CaseSensitivity case_sensitivity) const
+bool ByteString::matches(StringView mask, Vector<MaskSpan>& mask_spans, CaseSensitivity case_sensitivity) const
 {
     return StringUtils::matches(*this, mask, case_sensitivity, &mask_spans);
 }
 
-bool DeprecatedString::matches(StringView mask, CaseSensitivity case_sensitivity) const
+bool ByteString::matches(StringView mask, CaseSensitivity case_sensitivity) const
 {
     return StringUtils::matches(*this, mask, case_sensitivity);
 }
 
-bool DeprecatedString::contains(StringView needle, CaseSensitivity case_sensitivity) const
+bool ByteString::contains(StringView needle, CaseSensitivity case_sensitivity) const
 {
     return StringUtils::contains(*this, needle, case_sensitivity);
 }
 
-bool DeprecatedString::contains(char needle, CaseSensitivity case_sensitivity) const
+bool ByteString::contains(char needle, CaseSensitivity case_sensitivity) const
 {
     return StringUtils::contains(*this, StringView(&needle, 1), case_sensitivity);
 }
 
-bool DeprecatedString::equals_ignoring_ascii_case(StringView other) const
+bool ByteString::equals_ignoring_ascii_case(StringView other) const
 {
     return StringUtils::equals_ignoring_ascii_case(view(), other);
 }
 
-DeprecatedString DeprecatedString::reverse() const
+ByteString ByteString::reverse() const
 {
     StringBuilder reversed_string(length());
     for (size_t i = length(); i-- > 0;) {
         reversed_string.append(characters()[i]);
     }
-    return reversed_string.to_deprecated_string();
+    return reversed_string.to_byte_string();
 }
 
-DeprecatedString escape_html_entities(StringView html)
+ByteString escape_html_entities(StringView html)
 {
     StringBuilder builder;
     for (size_t i = 0; i < html.length(); ++i) {
@@ -370,40 +370,40 @@ DeprecatedString escape_html_entities(StringView html)
         else
             builder.append(html[i]);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString::DeprecatedString(DeprecatedFlyString const& string)
+ByteString::ByteString(DeprecatedFlyString const& string)
     : m_impl(*(string.impl() ?: &StringImpl::the_empty_stringimpl()))
 {
 }
 
-DeprecatedString DeprecatedString::to_lowercase() const
+ByteString ByteString::to_lowercase() const
 {
     return m_impl->to_lowercase();
 }
 
-DeprecatedString DeprecatedString::to_uppercase() const
+ByteString ByteString::to_uppercase() const
 {
     return m_impl->to_uppercase();
 }
 
-DeprecatedString DeprecatedString::to_snakecase() const
+ByteString ByteString::to_snakecase() const
 {
     return StringUtils::to_snakecase(*this);
 }
 
-DeprecatedString DeprecatedString::to_titlecase() const
+ByteString ByteString::to_titlecase() const
 {
     return StringUtils::to_titlecase(*this);
 }
 
-DeprecatedString DeprecatedString::invert_case() const
+ByteString ByteString::invert_case() const
 {
     return StringUtils::invert_case(*this);
 }
 
-bool DeprecatedString::operator==(char const* cstring) const
+bool ByteString::operator==(char const* cstring) const
 {
     if (!cstring)
         return is_empty();
@@ -411,28 +411,28 @@ bool DeprecatedString::operator==(char const* cstring) const
     return view() == cstring;
 }
 
-DeprecatedString DeprecatedString::vformatted(StringView fmtstr, TypeErasedFormatParams& params)
+ByteString ByteString::vformatted(StringView fmtstr, TypeErasedFormatParams& params)
 {
     StringBuilder builder;
     MUST(vformat(builder, fmtstr, params));
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-Vector<size_t> DeprecatedString::find_all(StringView needle) const
+Vector<size_t> ByteString::find_all(StringView needle) const
 {
     return StringUtils::find_all(*this, needle);
 }
 
-DeprecatedStringCodePointIterator DeprecatedString::code_points() const
+DeprecatedStringCodePointIterator ByteString::code_points() const
 {
     return DeprecatedStringCodePointIterator(*this);
 }
 
-ErrorOr<DeprecatedString> DeprecatedString::from_utf8(ReadonlyBytes bytes)
+ErrorOr<ByteString> ByteString::from_utf8(ReadonlyBytes bytes)
 {
     if (!Utf8View(bytes).validate())
-        return Error::from_string_literal("DeprecatedString::from_utf8: Input was not valid UTF-8");
-    return DeprecatedString { *StringImpl::create(bytes) };
+        return Error::from_string_literal("ByteString::from_utf8: Input was not valid UTF-8");
+    return ByteString { *StringImpl::create(bytes) };
 }
 
 }
diff --git a/AK/DeprecatedString.h b/AK/ByteString.h
similarity index 63%
rename from AK/DeprecatedString.h
rename to AK/ByteString.h
index 4813342bded..dc48d63c48b 100644
--- a/AK/DeprecatedString.h
+++ b/AK/ByteString.h
@@ -16,93 +16,93 @@
 
 namespace AK {
 
-// DeprecatedString is a convenience wrapper around StringImpl, suitable for passing
+// ByteString is a convenience wrapper around StringImpl, suitable for passing
 // around as a value type. It's basically the same as passing around a
 // RefPtr<StringImpl const>, with a bit of syntactic sugar.
 //
 // Note that StringImpl is an immutable object that cannot shrink or grow.
 // Its allocation size is snugly tailored to the specific string it contains.
-// Copying a DeprecatedString is very efficient, since the internal StringImpl is
+// Copying a ByteString is very efficient, since the internal StringImpl is
 // retainable and so copying only requires modifying the ref count.
 //
-// There are three main ways to construct a new DeprecatedString:
+// There are three main ways to construct a new ByteString:
 //
-//     s = DeprecatedString("some literal");
+//     s = ByteString("some literal");
 //
-//     s = DeprecatedString::formatted("{} little piggies", m_piggies);
+//     s = ByteString::formatted("{} little piggies", m_piggies);
 //
 //     StringBuilder builder;
 //     builder.append("abc");
 //     builder.append("123");
-//     s = builder.to_deprecated_string();
+//     s = builder.to_byte_string();
 
-class DeprecatedString {
+class ByteString {
 public:
-    ~DeprecatedString() = default;
+    ~ByteString() = default;
 
-    DeprecatedString()
+    ByteString()
         : m_impl(StringImpl::the_empty_stringimpl())
     {
     }
 
-    DeprecatedString(StringView view)
+    ByteString(StringView view)
         : m_impl(*StringImpl::create(view.characters_without_null_termination(), view.length()))
     {
     }
 
-    DeprecatedString(DeprecatedString const& other)
+    ByteString(ByteString const& other)
         : m_impl(other.m_impl)
     {
     }
 
-    DeprecatedString(DeprecatedString&& other)
+    ByteString(ByteString&& other)
         : m_impl(move(other.m_impl))
     {
         other.m_impl = StringImpl::the_empty_stringimpl();
     }
 
-    DeprecatedString(char const* cstring, ShouldChomp shouldChomp = NoChomp)
+    ByteString(char const* cstring, ShouldChomp shouldChomp = NoChomp)
         : m_impl(*StringImpl::create(cstring, shouldChomp))
     {
     }
 
-    DeprecatedString(char const* cstring, size_t length, ShouldChomp shouldChomp = NoChomp)
+    ByteString(char const* cstring, size_t length, ShouldChomp shouldChomp = NoChomp)
         : m_impl(*StringImpl::create(cstring, length, shouldChomp))
     {
     }
 
-    explicit DeprecatedString(ReadonlyBytes bytes, ShouldChomp shouldChomp = NoChomp)
+    explicit ByteString(ReadonlyBytes bytes, ShouldChomp shouldChomp = NoChomp)
         : m_impl(*StringImpl::create(bytes, shouldChomp))
     {
     }
 
-    DeprecatedString(StringImpl const& impl)
+    ByteString(StringImpl const& impl)
         : m_impl(impl)
     {
     }
 
-    DeprecatedString(NonnullRefPtr<StringImpl const>&& impl)
+    ByteString(NonnullRefPtr<StringImpl const>&& impl)
         : m_impl(*move(impl))
     {
     }
 
-    DeprecatedString(DeprecatedFlyString const&);
+    ByteString(DeprecatedFlyString const&);
 
-    static ErrorOr<DeprecatedString> from_utf8(ReadonlyBytes);
-    static ErrorOr<DeprecatedString> from_utf8(StringView string) { return from_utf8(string.bytes()); }
+    static ErrorOr<ByteString> from_utf8(ReadonlyBytes);
+    static ErrorOr<ByteString> from_utf8(StringView string) { return from_utf8(string.bytes()); }
 
-    [[nodiscard]] static DeprecatedString repeated(char, size_t count);
-    [[nodiscard]] static DeprecatedString repeated(StringView, size_t count);
+    [[nodiscard]] static ByteString repeated(char, size_t count);
+    [[nodiscard]] static ByteString repeated(StringView, size_t count);
 
-    [[nodiscard]] static DeprecatedString bijective_base_from(size_t value, unsigned base = 26, StringView map = {});
-    [[nodiscard]] static DeprecatedString roman_number_from(size_t value);
+    [[nodiscard]] static ByteString bijective_base_from(size_t value, unsigned base = 26, StringView map = {});
+    [[nodiscard]] static ByteString roman_number_from(size_t value);
 
     template<class SeparatorType, class CollectionType>
-    [[nodiscard]] static DeprecatedString join(SeparatorType const& separator, CollectionType const& collection, StringView fmtstr = "{}"sv)
+    [[nodiscard]] static ByteString join(SeparatorType const& separator, CollectionType const& collection, StringView fmtstr = "{}"sv)
     {
         StringBuilder builder;
         builder.join(separator, collection, fmtstr);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 
     [[nodiscard]] bool matches(StringView mask, CaseSensitivity = CaseSensitivity::CaseInsensitive) const;
@@ -117,17 +117,17 @@ public:
     [[nodiscard]] Optional<float> to_float(TrimWhitespace = TrimWhitespace::Yes) const;
 #endif
 
-    [[nodiscard]] DeprecatedString to_lowercase() const;
-    [[nodiscard]] DeprecatedString to_uppercase() const;
-    [[nodiscard]] DeprecatedString to_snakecase() const;
-    [[nodiscard]] DeprecatedString to_titlecase() const;
-    [[nodiscard]] DeprecatedString invert_case() const;
+    [[nodiscard]] ByteString to_lowercase() const;
+    [[nodiscard]] ByteString to_uppercase() const;
+    [[nodiscard]] ByteString to_snakecase() const;
+    [[nodiscard]] ByteString to_titlecase() const;
+    [[nodiscard]] ByteString invert_case() const;
 
     [[nodiscard]] bool is_whitespace() const { return StringUtils::is_whitespace(*this); }
 
     [[nodiscard]] DeprecatedStringCodePointIterator code_points() const;
 
-    [[nodiscard]] DeprecatedString trim(StringView characters, TrimMode mode = TrimMode::Both) const
+    [[nodiscard]] ByteString trim(StringView characters, TrimMode mode = TrimMode::Both) const
     {
         auto trimmed_view = StringUtils::trim(view(), characters, mode);
         if (view() == trimmed_view)
@@ -135,7 +135,7 @@ public:
         return trimmed_view;
     }
 
-    [[nodiscard]] DeprecatedString trim_whitespace(TrimMode mode = TrimMode::Both) const
+    [[nodiscard]] ByteString trim_whitespace(TrimMode mode = TrimMode::Both) const
     {
         auto trimmed_view = StringUtils::trim_whitespace(view(), mode);
         if (view() == trimmed_view)
@@ -148,8 +148,8 @@ public:
     [[nodiscard]] bool contains(StringView, CaseSensitivity = CaseSensitivity::CaseSensitive) const;
     [[nodiscard]] bool contains(char, CaseSensitivity = CaseSensitivity::CaseSensitive) const;
 
-    [[nodiscard]] Vector<DeprecatedString> split_limit(char separator, size_t limit, SplitBehavior = SplitBehavior::Nothing) const;
-    [[nodiscard]] Vector<DeprecatedString> split(char separator, SplitBehavior = SplitBehavior::Nothing) const;
+    [[nodiscard]] Vector<ByteString> split_limit(char separator, size_t limit, SplitBehavior = SplitBehavior::Nothing) const;
+    [[nodiscard]] Vector<ByteString> split(char separator, SplitBehavior = SplitBehavior::Nothing) const;
     [[nodiscard]] Vector<StringView> split_view(char separator, SplitBehavior = SplitBehavior::Nothing) const;
     [[nodiscard]] Vector<StringView> split_view(Function<bool(char)> separator, SplitBehavior = SplitBehavior::Nothing) const;
 
@@ -163,8 +163,8 @@ public:
 
     [[nodiscard]] StringView find_last_split_view(char separator) const { return view().find_last_split_view(separator); }
 
-    [[nodiscard]] DeprecatedString substring(size_t start, size_t length) const;
-    [[nodiscard]] DeprecatedString substring(size_t start) const;
+    [[nodiscard]] ByteString substring(size_t start, size_t length) const;
+    [[nodiscard]] ByteString substring(size_t start) const;
     [[nodiscard]] StringView substring_view(size_t start, size_t length) const;
     [[nodiscard]] StringView substring_view(size_t start) const;
 
@@ -190,7 +190,7 @@ public:
         return bit_cast<u8>((*m_impl)[i]);
     }
 
-    using ConstIterator = SimpleIterator<const DeprecatedString, char const>;
+    using ConstIterator = SimpleIterator<const ByteString, char const>;
 
     [[nodiscard]] constexpr ConstIterator begin() const { return ConstIterator::begin(*this); }
     [[nodiscard]] constexpr ConstIterator end() const { return ConstIterator::end(*this); }
@@ -200,47 +200,47 @@ public:
     [[nodiscard]] bool starts_with(char) const;
     [[nodiscard]] bool ends_with(char) const;
 
-    bool operator==(DeprecatedString const&) const;
+    bool operator==(ByteString const&) const;
 
     bool operator==(StringView) const;
 
     bool operator==(DeprecatedFlyString const&) const;
 
-    bool operator<(DeprecatedString const&) const;
-    bool operator>=(DeprecatedString const& other) const { return !(*this < other); }
+    bool operator<(ByteString const&) const;
+    bool operator>=(ByteString const& other) const { return !(*this < other); }
     bool operator>=(char const* other) const { return !(*this < other); }
 
-    bool operator>(DeprecatedString const&) const;
-    bool operator<=(DeprecatedString const& other) const { return !(*this > other); }
+    bool operator>(ByteString const&) const;
+    bool operator<=(ByteString const& other) const { return !(*this > other); }
     bool operator<=(char const* other) const { return !(*this > other); }
 
     bool operator==(char const* cstring) const;
 
-    [[nodiscard]] DeprecatedString isolated_copy() const;
+    [[nodiscard]] ByteString isolated_copy() const;
 
-    [[nodiscard]] static DeprecatedString empty()
+    [[nodiscard]] static ByteString empty()
     {
         return StringImpl::the_empty_stringimpl();
     }
 
     [[nodiscard]] StringImpl const* impl() const { return m_impl.ptr(); }
 
-    DeprecatedString& operator=(DeprecatedString&& other)
+    ByteString& operator=(ByteString&& other)
     {
         if (this != &other)
             m_impl = move(other.m_impl);
         return *this;
     }
 
-    DeprecatedString& operator=(DeprecatedString const& other)
+    ByteString& operator=(ByteString const& other)
     {
         if (this != &other)
-            m_impl = const_cast<DeprecatedString&>(other).m_impl;
+            m_impl = const_cast<ByteString&>(other).m_impl;
         return *this;
     }
 
     template<OneOf<ReadonlyBytes, Bytes> T>
-    DeprecatedString& operator=(T bytes)
+    ByteString& operator=(T bytes)
     {
         m_impl = *StringImpl::create(bytes);
         return *this;
@@ -254,24 +254,24 @@ public:
     [[nodiscard]] ByteBuffer to_byte_buffer() const;
 
     template<typename BufferType>
-    [[nodiscard]] static DeprecatedString copy(BufferType const& buffer, ShouldChomp should_chomp = NoChomp)
+    [[nodiscard]] static ByteString copy(BufferType const& buffer, ShouldChomp should_chomp = NoChomp)
     {
         if (buffer.is_empty())
             return empty();
-        return DeprecatedString(reinterpret_cast<char const*>(buffer.data()), buffer.size(), should_chomp);
+        return ByteString(reinterpret_cast<char const*>(buffer.data()), buffer.size(), should_chomp);
     }
 
-    [[nodiscard]] static DeprecatedString vformatted(StringView fmtstr, TypeErasedFormatParams&);
+    [[nodiscard]] static ByteString vformatted(StringView fmtstr, TypeErasedFormatParams&);
 
     template<typename... Parameters>
-    [[nodiscard]] static DeprecatedString formatted(CheckedFormatString<Parameters...>&& fmtstr, Parameters const&... parameters)
+    [[nodiscard]] static ByteString formatted(CheckedFormatString<Parameters...>&& fmtstr, Parameters const&... parameters)
     {
         VariadicFormatParams<AllowDebugOnlyFormatters::No, Parameters...> variadic_format_parameters { parameters... };
         return vformatted(fmtstr.view(), variadic_format_parameters);
     }
 
     template<Arithmetic T>
-    [[nodiscard]] static DeprecatedString number(T value)
+    [[nodiscard]] static ByteString number(T value)
     {
         return formatted("{}", value);
     }
@@ -281,9 +281,9 @@ public:
         return { characters(), length() };
     }
 
-    [[nodiscard]] DeprecatedString replace(StringView needle, StringView replacement, ReplaceMode replace_mode = ReplaceMode::All) const { return StringUtils::replace(*this, needle, replacement, replace_mode); }
+    [[nodiscard]] ByteString replace(StringView needle, StringView replacement, ReplaceMode replace_mode = ReplaceMode::All) const { return StringUtils::replace(*this, needle, replacement, replace_mode); }
     [[nodiscard]] size_t count(StringView needle) const { return StringUtils::count(*this, needle); }
-    [[nodiscard]] DeprecatedString reverse() const;
+    [[nodiscard]] ByteString reverse() const;
 
     template<typename... Ts>
     [[nodiscard]] ALWAYS_INLINE constexpr bool is_one_of(Ts&&... strings) const
@@ -308,17 +308,17 @@ private:
 };
 
 template<>
-struct Traits<DeprecatedString> : public DefaultTraits<DeprecatedString> {
-    static unsigned hash(DeprecatedString const& s) { return s.impl() ? s.impl()->hash() : 0; }
+struct Traits<ByteString> : public DefaultTraits<ByteString> {
+    static unsigned hash(ByteString const& s) { return s.impl() ? s.impl()->hash() : 0; }
 };
 
 // FIXME: Rename this to indicate that it's about ASCII-only case insensitivity.
-struct CaseInsensitiveStringTraits : public Traits<DeprecatedString> {
-    static unsigned hash(DeprecatedString const& s) { return s.impl() ? s.impl()->case_insensitive_hash() : 0; }
-    static bool equals(DeprecatedString const& a, DeprecatedString const& b) { return a.equals_ignoring_ascii_case(b); }
+struct CaseInsensitiveStringTraits : public Traits<ByteString> {
+    static unsigned hash(ByteString const& s) { return s.impl() ? s.impl()->case_insensitive_hash() : 0; }
+    static bool equals(ByteString const& a, ByteString const& b) { return a.equals_ignoring_ascii_case(b); }
 };
 
-DeprecatedString escape_html_entities(StringView html);
+ByteString escape_html_entities(StringView html);
 
 }
 
diff --git a/AK/CMakeLists.txt b/AK/CMakeLists.txt
index 366b1d271fb..15ebea36de2 100644
--- a/AK/CMakeLists.txt
+++ b/AK/CMakeLists.txt
@@ -6,7 +6,7 @@ set(AK_SOURCES
     CountingStream.cpp
     DOSPackedTime.cpp
     DeprecatedFlyString.cpp
-    DeprecatedString.cpp
+    ByteString.cpp
     Error.cpp
     FloatingPointStringConversions.cpp
     FlyString.cpp
diff --git a/AK/Demangle.h b/AK/Demangle.h
index 0d6484298ba..3321256f451 100644
--- a/AK/Demangle.h
+++ b/AK/Demangle.h
@@ -8,17 +8,17 @@
 
 #ifndef KERNEL
 
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #    include <AK/StringView.h>
 #    include <cxxabi.h>
 
 namespace AK {
 
-inline DeprecatedString demangle(StringView name)
+inline ByteString demangle(StringView name)
 {
     int status = 0;
-    auto* demangled_name = abi::__cxa_demangle(name.to_deprecated_string().characters(), nullptr, nullptr, &status);
-    auto string = DeprecatedString(status == 0 ? StringView { demangled_name, strlen(demangled_name) } : name);
+    auto* demangled_name = abi::__cxa_demangle(name.to_byte_string().characters(), nullptr, nullptr, &status);
+    auto string = ByteString(status == 0 ? StringView { demangled_name, strlen(demangled_name) } : name);
     if (status == 0)
         free(demangled_name);
     return string;
diff --git a/AK/DeprecatedFlyString.cpp b/AK/DeprecatedFlyString.cpp
index cc9f50de78a..0ac1f52f97f 100644
--- a/AK/DeprecatedFlyString.cpp
+++ b/AK/DeprecatedFlyString.cpp
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/DeprecatedFlyString.h>
-#include <AK/DeprecatedString.h>
 #include <AK/HashTable.h>
 #include <AK/Optional.h>
 #include <AK/Singleton.h>
@@ -36,7 +36,7 @@ void DeprecatedFlyString::did_destroy_impl(Badge<StringImpl>, StringImpl& impl)
     fly_impls().remove(&impl);
 }
 
-DeprecatedFlyString::DeprecatedFlyString(DeprecatedString const& string)
+DeprecatedFlyString::DeprecatedFlyString(ByteString const& string)
 {
     if (string.impl()->is_fly()) {
         m_impl = string.impl();
@@ -61,7 +61,7 @@ DeprecatedFlyString::DeprecatedFlyString(StringView string)
         return string == *candidate;
     });
     if (it == fly_impls().end()) {
-        auto new_string = string.to_deprecated_string();
+        auto new_string = string.to_byte_string();
         fly_impls().set(new_string.impl());
         new_string.impl()->set_fly({}, true);
         m_impl = new_string.impl();
@@ -122,10 +122,10 @@ bool DeprecatedFlyString::ends_with(StringView str, CaseSensitivity case_sensiti
 
 DeprecatedFlyString DeprecatedFlyString::to_lowercase() const
 {
-    return DeprecatedString(*m_impl).to_lowercase();
+    return ByteString(*m_impl).to_lowercase();
 }
 
-bool DeprecatedFlyString::operator==(DeprecatedString const& other) const
+bool DeprecatedFlyString::operator==(ByteString const& other) const
 {
     return m_impl == other.impl() || view() == other.view();
 }
diff --git a/AK/DeprecatedFlyString.h b/AK/DeprecatedFlyString.h
index b7b0ca03750..174b2d9d184 100644
--- a/AK/DeprecatedFlyString.h
+++ b/AK/DeprecatedFlyString.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringUtils.h>
 
 namespace AK {
@@ -22,10 +22,10 @@ public:
         : m_impl(move(other.m_impl))
     {
     }
-    DeprecatedFlyString(DeprecatedString const&);
+    DeprecatedFlyString(ByteString const&);
     DeprecatedFlyString(StringView);
     DeprecatedFlyString(char const* string)
-        : DeprecatedFlyString(static_cast<DeprecatedString>(string))
+        : DeprecatedFlyString(static_cast<ByteString>(string))
     {
     }
 
@@ -54,7 +54,7 @@ public:
 
     bool operator==(DeprecatedFlyString const& other) const { return m_impl == other.m_impl; }
 
-    bool operator==(DeprecatedString const&) const;
+    bool operator==(ByteString const&) const;
 
     bool operator==(StringView) const;
 
diff --git a/AK/Error.h b/AK/Error.h
index 351d2853498..9ed9a53124a 100644
--- a/AK/Error.h
+++ b/AK/Error.h
@@ -43,10 +43,10 @@ public:
     }
     static Error from_string_view(StringView string_literal) { return Error(string_literal); }
 
-    template<OneOf<DeprecatedString, DeprecatedFlyString, String, FlyString> T>
+    template<OneOf<ByteString, DeprecatedFlyString, String, FlyString> T>
     static Error from_string_view(T)
     {
-        // `Error::from_string_view(DeprecatedString::formatted(...))` is a somewhat common mistake, which leads to a UAF situation.
+        // `Error::from_string_view(ByteString::formatted(...))` is a somewhat common mistake, which leads to a UAF situation.
         // If your string outlives this error and _isn't_ a temporary being passed to this function, explicitly call .view() on it to resolve to the StringView overload.
         static_assert(DependentFalse<T>, "Error::from_string_view(String) is almost always a use-after-free");
         VERIFY_NOT_REACHED();
diff --git a/AK/FlyString.h b/AK/FlyString.h
index 7e939e62970..9fe8786a383 100644
--- a/AK/FlyString.h
+++ b/AK/FlyString.h
@@ -22,7 +22,7 @@ public:
 
     static ErrorOr<FlyString> from_utf8(StringView);
     template<typename T>
-    requires(IsOneOf<RemoveCVReference<T>, DeprecatedString, DeprecatedFlyString, FlyString, String>)
+    requires(IsOneOf<RemoveCVReference<T>, ByteString, DeprecatedFlyString, FlyString, String>)
     static ErrorOr<String> from_utf8(T&&) = delete;
 
     FlyString(String const&);
diff --git a/AK/Format.cpp b/AK/Format.cpp
index f8a4cfbd354..237c48621cc 100644
--- a/AK/Format.cpp
+++ b/AK/Format.cpp
@@ -274,7 +274,7 @@ ErrorOr<void> FormatBuilder::put_u64(
 
     size_t used_by_prefix = 0;
     if (align == Align::Right && zero_pad) {
-        // We want DeprecatedString::formatted("{:#08x}", 32) to produce '0x00000020' instead of '0x000020'. This
+        // We want ByteString::formatted("{:#08x}", 32) to produce '0x00000020' instead of '0x000020'. This
         // behavior differs from both fmtlib and printf, but is more intuitive.
         used_by_prefix = 0;
     } else {
@@ -1131,13 +1131,13 @@ void vout(LogLevel log_level, StringView fmtstr, TypeErasedFormatParams& params,
 
 #ifndef KERNEL
 // FIXME: Deduplicate with Core::Process:get_name()
-[[gnu::used]] static DeprecatedString process_name_helper()
+[[gnu::used]] static ByteString process_name_helper()
 {
 #    if defined(AK_OS_SERENITY)
     char buffer[BUFSIZ] = {};
     int rc = get_process_name(buffer, BUFSIZ);
     if (rc != 0)
-        return DeprecatedString {};
+        return ByteString {};
     return StringView { buffer, strlen(buffer) };
 #    elif defined(AK_LIBC_GLIBC) || (defined(AK_OS_LINUX) && !defined(AK_OS_ANDROID))
     return StringView { program_invocation_name, strlen(program_invocation_name) };
diff --git a/AK/Format.h b/AK/Format.h
index ef546593ad8..0212d419f64 100644
--- a/AK/Format.h
+++ b/AK/Format.h
@@ -501,7 +501,7 @@ struct Formatter<unsigned char[Size]> : Formatter<StringView> {
     }
 };
 template<>
-struct Formatter<DeprecatedString> : Formatter<StringView> {
+struct Formatter<ByteString> : Formatter<StringView> {
 };
 template<>
 struct Formatter<DeprecatedFlyString> : Formatter<StringView> {
diff --git a/AK/Forward.h b/AK/Forward.h
index 3fc2231aee8..24f18de69f9 100644
--- a/AK/Forward.h
+++ b/AK/Forward.h
@@ -27,7 +27,7 @@ class CircularBuffer;
 class ConstrainedStream;
 class CountingStream;
 class DeprecatedFlyString;
-class DeprecatedString;
+class ByteString;
 class DeprecatedStringCodePointIterator;
 class Duration;
 class Error;
@@ -159,12 +159,12 @@ using AK::BigEndianOutputBitStream;
 using AK::Bitmap;
 using AK::ByteBuffer;
 using AK::Bytes;
+using AK::ByteString;
 using AK::CircularBuffer;
 using AK::CircularQueue;
 using AK::ConstrainedStream;
 using AK::CountingStream;
 using AK::DeprecatedFlyString;
-using AK::DeprecatedString;
 using AK::DeprecatedStringCodePointIterator;
 using AK::DoublyLinkedList;
 using AK::Duration;
diff --git a/AK/GenericLexer.cpp b/AK/GenericLexer.cpp
index 6a93edbad56..69039d81c8a 100644
--- a/AK/GenericLexer.cpp
+++ b/AK/GenericLexer.cpp
@@ -11,7 +11,7 @@
 #include <AK/StringBuilder.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #    include <AK/Utf16View.h>
 #endif
 
@@ -186,7 +186,7 @@ template ErrorOr<u64> GenericLexer::consume_decimal_integer<u64>();
 template ErrorOr<i64> GenericLexer::consume_decimal_integer<i64>();
 
 #ifndef KERNEL
-Optional<DeprecatedString> GenericLexer::consume_and_unescape_string(char escape_char)
+Optional<ByteString> GenericLexer::consume_and_unescape_string(char escape_char)
 {
     auto view = consume_quoted_string(escape_char);
     if (view.is_null())
@@ -195,7 +195,7 @@ Optional<DeprecatedString> GenericLexer::consume_and_unescape_string(char escape
     StringBuilder builder;
     for (size_t i = 0; i < view.length(); ++i)
         builder.append(consume_escaped_character(escape_char));
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 auto GenericLexer::consume_escaped_code_point(bool combine_surrogate_pairs) -> Result<u32, UnicodeEscapeError>
diff --git a/AK/GenericLexer.h b/AK/GenericLexer.h
index 4f2f2bb11e0..ab1756be248 100644
--- a/AK/GenericLexer.h
+++ b/AK/GenericLexer.h
@@ -92,7 +92,7 @@ public:
     }
 
 #ifndef KERNEL
-    bool consume_specific(DeprecatedString const& next)
+    bool consume_specific(ByteString const& next)
     {
         return consume_specific(StringView { next });
     }
@@ -126,7 +126,7 @@ public:
     StringView consume_until(StringView);
     StringView consume_quoted_string(char escape_char = 0);
 #ifndef KERNEL
-    Optional<DeprecatedString> consume_and_unescape_string(char escape_char = '\\');
+    Optional<ByteString> consume_and_unescape_string(char escape_char = '\\');
 #endif
     template<Integral T>
     ErrorOr<T> consume_decimal_integer();
diff --git a/AK/Hex.cpp b/AK/Hex.cpp
index 8e09729fbbb..37aeb571396 100644
--- a/AK/Hex.cpp
+++ b/AK/Hex.cpp
@@ -45,14 +45,14 @@ ErrorOr<NonnullOwnPtr<Kernel::KString>> encode_hex(const ReadonlyBytes input)
     return Kernel::KString::try_create(output.string_view());
 }
 #else
-DeprecatedString encode_hex(const ReadonlyBytes input)
+ByteString encode_hex(const ReadonlyBytes input)
 {
     StringBuilder output(input.size() * 2);
 
     for (auto ch : input)
         output.appendff("{:02x}", ch);
 
-    return output.to_deprecated_string();
+    return output.to_byte_string();
 }
 #endif
 
diff --git a/AK/Hex.h b/AK/Hex.h
index b65f46757bc..6c56480166c 100644
--- a/AK/Hex.h
+++ b/AK/Hex.h
@@ -13,7 +13,7 @@
 #ifdef KERNEL
 #    include <Kernel/Library/KString.h>
 #else
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace AK {
@@ -34,7 +34,7 @@ ErrorOr<ByteBuffer> decode_hex(StringView);
 #ifdef KERNEL
 ErrorOr<NonnullOwnPtr<Kernel::KString>> encode_hex(ReadonlyBytes);
 #else
-DeprecatedString encode_hex(ReadonlyBytes);
+ByteString encode_hex(ReadonlyBytes);
 #endif
 
 }
diff --git a/AK/IPv4Address.h b/AK/IPv4Address.h
index f927777508c..7e88968acea 100644
--- a/AK/IPv4Address.h
+++ b/AK/IPv4Address.h
@@ -17,7 +17,7 @@
 #    include <AK/Error.h>
 #    include <Kernel/Library/KString.h>
 #else
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #    include <AK/String.h>
 #endif
 
@@ -67,18 +67,18 @@ public:
             octet(SubnetClass::D));
     }
 #else
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
-        return DeprecatedString::formatted("{}.{}.{}.{}",
+        return ByteString::formatted("{}.{}.{}.{}",
             octet(SubnetClass::A),
             octet(SubnetClass::B),
             octet(SubnetClass::C),
             octet(SubnetClass::D));
     }
 
-    DeprecatedString to_deprecated_string_reversed() const
+    ByteString to_byte_string_reversed() const
     {
-        return DeprecatedString::formatted("{}.{}.{}.{}",
+        return ByteString::formatted("{}.{}.{}.{}",
             octet(SubnetClass::D),
             octet(SubnetClass::C),
             octet(SubnetClass::B),
@@ -179,7 +179,7 @@ template<>
 struct Formatter<IPv4Address> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, IPv4Address value)
     {
-        return Formatter<StringView>::format(builder, value.to_deprecated_string());
+        return Formatter<StringView>::format(builder, value.to_byte_string());
     }
 };
 #endif
diff --git a/AK/Iterator.h b/AK/Iterator.h
index 594c2141bdb..d09cbeaf261 100644
--- a/AK/Iterator.h
+++ b/AK/Iterator.h
@@ -71,7 +71,7 @@ private:
     {
         using RawContainerType = RemoveCV<Container>;
 
-        if constexpr (IsSame<StringView, RawContainerType> || IsSame<DeprecatedString, RawContainerType>)
+        if constexpr (IsSame<StringView, RawContainerType> || IsSame<ByteString, RawContainerType>)
             return { container, container.length() };
         else
             return { container, container.size() };
diff --git a/AK/JsonArray.h b/AK/JsonArray.h
index 9b732036bba..cc0a7b74437 100644
--- a/AK/JsonArray.h
+++ b/AK/JsonArray.h
@@ -73,7 +73,7 @@ public:
     template<typename Builder>
     void serialize(Builder&) const;
 
-    [[nodiscard]] DeprecatedString to_deprecated_string() const { return serialized<StringBuilder>(); }
+    [[nodiscard]] ByteString to_byte_string() const { return serialized<StringBuilder>(); }
 
     template<typename Callback>
     void for_each(Callback callback) const
@@ -111,7 +111,7 @@ inline typename Builder::OutputType JsonArray::serialized() const
 {
     Builder builder;
     serialize(builder);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/AK/JsonArraySerializer.h b/AK/JsonArraySerializer.h
index ef45da294d3..383d420a9ec 100644
--- a/AK/JsonArraySerializer.h
+++ b/AK/JsonArraySerializer.h
@@ -68,7 +68,7 @@ public:
     }
 
 #ifndef KERNEL
-    ErrorOr<void> add(DeprecatedString const& value)
+    ErrorOr<void> add(ByteString const& value)
     {
         TRY(begin_item());
         if constexpr (IsLegacyBuilder<Builder>) {
diff --git a/AK/JsonObject.cpp b/AK/JsonObject.cpp
index 5d280143559..261b97dd0be 100644
--- a/AK/JsonObject.cpp
+++ b/AK/JsonObject.cpp
@@ -109,7 +109,7 @@ Optional<bool> JsonObject::get_bool(StringView key) const
 }
 
 #if !defined(KERNEL)
-Optional<DeprecatedString> JsonObject::get_deprecated_string(StringView key) const
+Optional<ByteString> JsonObject::get_byte_string(StringView key) const
 {
     auto maybe_value = get(key);
     if (maybe_value.has_value() && maybe_value->is_string())
@@ -249,7 +249,7 @@ bool JsonObject::has_double(StringView key) const
 }
 #endif
 
-void JsonObject::set(DeprecatedString const& key, JsonValue value)
+void JsonObject::set(ByteString const& key, JsonValue value)
 {
     m_members.set(key, move(value));
 }
@@ -259,7 +259,7 @@ bool JsonObject::remove(StringView key)
     return m_members.remove(key);
 }
 
-DeprecatedString JsonObject::to_deprecated_string() const
+ByteString JsonObject::to_byte_string() const
 {
     return serialized<StringBuilder>();
 }
diff --git a/AK/JsonObject.h b/AK/JsonObject.h
index a6d14a4b1c9..ff09afb4644 100644
--- a/AK/JsonObject.h
+++ b/AK/JsonObject.h
@@ -8,8 +8,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/Concepts.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Error.h>
 #include <AK/HashMap.h>
 #include <AK/JsonArray.h>
@@ -20,7 +20,7 @@ namespace AK {
 
 class JsonObject {
     template<typename Callback>
-    using CallbackErrorType = decltype(declval<Callback>()(declval<DeprecatedString const&>(), declval<JsonValue const&>()).release_error());
+    using CallbackErrorType = decltype(declval<Callback>()(declval<ByteString const&>(), declval<JsonValue const&>()).release_error());
 
 public:
     JsonObject();
@@ -78,7 +78,7 @@ public:
     Optional<bool> get_bool(StringView key) const;
 
 #if !defined(KERNEL)
-    Optional<DeprecatedString> get_deprecated_string(StringView key) const;
+    Optional<ByteString> get_byte_string(StringView key) const;
 #endif
 
     Optional<JsonObject const&> get_object(StringView key) const;
@@ -89,7 +89,7 @@ public:
     Optional<float> get_float_with_precision_loss(StringView key) const;
 #endif
 
-    void set(DeprecatedString const& key, JsonValue value);
+    void set(ByteString const& key, JsonValue value);
 
     template<typename Callback>
     void for_each_member(Callback callback) const
@@ -98,7 +98,7 @@ public:
             callback(member.key, member.value);
     }
 
-    template<FallibleFunction<DeprecatedString const&, JsonValue const&> Callback>
+    template<FallibleFunction<ByteString const&, JsonValue const&> Callback>
     ErrorOr<void, CallbackErrorType<Callback>> try_for_each_member(Callback&& callback) const
     {
         for (auto const& member : m_members)
@@ -114,10 +114,10 @@ public:
     template<typename Builder>
     void serialize(Builder&) const;
 
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
+    [[nodiscard]] ByteString to_byte_string() const;
 
 private:
-    OrderedHashMap<DeprecatedString, JsonValue> m_members;
+    OrderedHashMap<ByteString, JsonValue> m_members;
 };
 
 template<typename Builder>
@@ -135,7 +135,7 @@ inline typename Builder::OutputType JsonObject::serialized() const
 {
     Builder builder;
     serialize(builder);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 template<typename Builder>
@@ -186,7 +186,7 @@ inline typename Builder::OutputType JsonValue::serialized() const
 {
     Builder builder;
     serialize(builder);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/AK/JsonObjectSerializer.h b/AK/JsonObjectSerializer.h
index 518856e66aa..d5f858830a3 100644
--- a/AK/JsonObjectSerializer.h
+++ b/AK/JsonObjectSerializer.h
@@ -63,7 +63,7 @@ public:
     }
 
 #ifndef KERNEL
-    ErrorOr<void> add(StringView key, DeprecatedString const& value)
+    ErrorOr<void> add(StringView key, ByteString const& value)
     {
         TRY(begin_item(key));
         if constexpr (IsLegacyBuilder<Builder>) {
diff --git a/AK/JsonParser.cpp b/AK/JsonParser.cpp
index 07159371eb6..e26e1fff08b 100644
--- a/AK/JsonParser.cpp
+++ b/AK/JsonParser.cpp
@@ -31,7 +31,7 @@ constexpr bool is_space(int ch)
 //                             │                       │
 //                             ╰─── u[0-9A-Za-z]{4}  ──╯
 //
-ErrorOr<DeprecatedString> JsonParser::consume_and_unescape_string()
+ErrorOr<ByteString> JsonParser::consume_and_unescape_string()
 {
     if (!consume_specific('"'))
         return Error::from_string_literal("JsonParser: Expected '\"'");
@@ -128,7 +128,7 @@ ErrorOr<DeprecatedString> JsonParser::consume_and_unescape_string()
         }
     }
 
-    return final_sb.to_deprecated_string();
+    return final_sb.to_byte_string();
 }
 
 ErrorOr<JsonValue> JsonParser::parse_object()
diff --git a/AK/JsonParser.h b/AK/JsonParser.h
index 38e9a65c9a4..88b373bfaf9 100644
--- a/AK/JsonParser.h
+++ b/AK/JsonParser.h
@@ -23,7 +23,7 @@ public:
 private:
     ErrorOr<JsonValue> parse_helper();
 
-    ErrorOr<DeprecatedString> consume_and_unescape_string();
+    ErrorOr<ByteString> consume_and_unescape_string();
     ErrorOr<JsonValue> parse_array();
     ErrorOr<JsonValue> parse_object();
     ErrorOr<JsonValue> parse_number();
diff --git a/AK/JsonPath.cpp b/AK/JsonPath.cpp
index 3a66e7643fe..b761757a277 100644
--- a/AK/JsonPath.cpp
+++ b/AK/JsonPath.cpp
@@ -31,16 +31,16 @@ JsonValue JsonPath::resolve(JsonValue const& top_root) const
     return root;
 }
 
-DeprecatedString JsonPath::to_deprecated_string() const
+ByteString JsonPath::to_byte_string() const
 {
     StringBuilder builder;
     builder.append("{ ."sv);
     for (auto const& el : *this) {
         builder.append("sv > "sv);
-        builder.append(el.to_deprecated_string());
+        builder.append(el.to_byte_string());
     }
     builder.append("sv }"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/AK/JsonPath.h b/AK/JsonPath.h
index 9b8364cdb03..f24f91684b3 100644
--- a/AK/JsonPath.h
+++ b/AK/JsonPath.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Types.h>
 #include <AK/Vector.h>
 
@@ -34,7 +34,7 @@ public:
     }
 
     Kind kind() const { return m_kind; }
-    DeprecatedString const& key() const
+    ByteString const& key() const
     {
         VERIFY(m_kind == Kind::Key);
         return m_key;
@@ -46,13 +46,13 @@ public:
         return m_index;
     }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
         switch (m_kind) {
         case Kind::Key:
             return key();
         case Kind::Index:
-            return DeprecatedString::number(index());
+            return ByteString::number(index());
         default:
             return "*";
         }
@@ -78,7 +78,7 @@ public:
 
 private:
     Kind m_kind;
-    DeprecatedString m_key;
+    ByteString m_key;
     size_t m_index { 0 };
 
     JsonPathElement(Kind kind)
@@ -90,7 +90,7 @@ private:
 class JsonPath : public Vector<JsonPathElement> {
 public:
     JsonValue resolve(JsonValue const&) const;
-    DeprecatedString to_deprecated_string() const;
+    ByteString to_byte_string() const;
 };
 
 }
diff --git a/AK/JsonValue.cpp b/AK/JsonValue.cpp
index 87619dd119d..b6c20341f77 100644
--- a/AK/JsonValue.cpp
+++ b/AK/JsonValue.cpp
@@ -155,7 +155,7 @@ JsonValue::JsonValue(long long unsigned value)
 }
 
 JsonValue::JsonValue(char const* cstring)
-    : JsonValue(DeprecatedString(cstring))
+    : JsonValue(ByteString(cstring))
 {
 }
 
@@ -167,7 +167,7 @@ JsonValue::JsonValue(double value)
 }
 #endif
 
-JsonValue::JsonValue(DeprecatedString const& value)
+JsonValue::JsonValue(ByteString const& value)
 {
     m_type = Type::String;
     m_value.as_string = const_cast<StringImpl*>(value.impl());
@@ -175,7 +175,7 @@ JsonValue::JsonValue(DeprecatedString const& value)
 }
 
 JsonValue::JsonValue(StringView value)
-    : JsonValue(value.to_deprecated_string())
+    : JsonValue(value.to_byte_string())
 {
 }
 
diff --git a/AK/JsonValue.h b/AK/JsonValue.h
index 85b6b9f73dd..9750392c11c 100644
--- a/AK/JsonValue.h
+++ b/AK/JsonValue.h
@@ -10,7 +10,7 @@
 #    error "JsonValue does not propagate allocation failures, so it is not safe to use in the kernel."
 #endif
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/Optional.h>
 #include <AK/StringBuilder.h>
@@ -52,7 +52,7 @@ public:
 
     JsonValue(double);
     JsonValue(char const*);
-    JsonValue(DeprecatedString const&);
+    JsonValue(ByteString const&);
     JsonValue(StringView);
 
     template<typename T>
@@ -78,14 +78,14 @@ public:
     template<typename Builder>
     void serialize(Builder&) const;
 
-    DeprecatedString as_string_or(DeprecatedString const& alternative) const
+    ByteString as_string_or(ByteString const& alternative) const
     {
         if (is_string())
             return as_string();
         return alternative;
     }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
         if (is_string())
             return as_string();
@@ -148,7 +148,7 @@ public:
         return m_value.as_bool;
     }
 
-    DeprecatedString as_string() const
+    ByteString as_string() const
     {
         VERIFY(is_string());
         return *m_value.as_string;
@@ -290,7 +290,7 @@ template<>
 struct Formatter<JsonValue> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, JsonValue const& value)
     {
-        return Formatter<StringView>::format(builder, value.to_deprecated_string());
+        return Formatter<StringView>::format(builder, value.to_byte_string());
     }
 };
 
diff --git a/AK/LexicalPath.cpp b/AK/LexicalPath.cpp
index b6c2181c296..b2f573b6ae5 100644
--- a/AK/LexicalPath.cpp
+++ b/AK/LexicalPath.cpp
@@ -14,7 +14,7 @@ namespace AK {
 
 char s_single_dot = '.';
 
-LexicalPath::LexicalPath(DeprecatedString path)
+LexicalPath::LexicalPath(ByteString path)
     : m_string(canonicalized_path(move(path)))
 {
     if (m_string.is_empty()) {
@@ -58,9 +58,9 @@ LexicalPath::LexicalPath(DeprecatedString path)
     }
 }
 
-Vector<DeprecatedString> LexicalPath::parts() const
+Vector<ByteString> LexicalPath::parts() const
 {
-    Vector<DeprecatedString> vector;
+    Vector<ByteString> vector;
     vector.ensure_capacity(m_parts.size());
     for (auto& part : m_parts)
         vector.unchecked_append(part);
@@ -88,7 +88,7 @@ bool LexicalPath::is_child_of(LexicalPath const& possible_parent) const
     return common_parts_with_parent == possible_parent.parts_view().span();
 }
 
-DeprecatedString LexicalPath::canonicalized_path(DeprecatedString path)
+ByteString LexicalPath::canonicalized_path(ByteString path)
 {
     // NOTE: We never allow an empty m_string, if it's empty, we just set it to '.'.
     if (path.is_empty())
@@ -101,7 +101,7 @@ DeprecatedString LexicalPath::canonicalized_path(DeprecatedString path)
     auto is_absolute = path[0] == '/';
     auto parts = path.split_view('/');
     size_t approximate_canonical_length = 0;
-    Vector<DeprecatedString> canonical_parts;
+    Vector<ByteString> canonical_parts;
 
     for (auto& part : parts) {
         if (part == ".")
@@ -131,10 +131,10 @@ DeprecatedString LexicalPath::canonicalized_path(DeprecatedString path)
     if (is_absolute)
         builder.append('/');
     builder.join('/', canonical_parts);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString LexicalPath::absolute_path(DeprecatedString dir_path, DeprecatedString target)
+ByteString LexicalPath::absolute_path(ByteString dir_path, ByteString target)
 {
     if (LexicalPath(target).is_absolute()) {
         return LexicalPath::canonicalized_path(target);
@@ -142,10 +142,10 @@ DeprecatedString LexicalPath::absolute_path(DeprecatedString dir_path, Deprecate
     return LexicalPath::canonicalized_path(join(dir_path, target).string());
 }
 
-DeprecatedString LexicalPath::relative_path(StringView a_path, StringView a_prefix)
+ByteString LexicalPath::relative_path(StringView a_path, StringView a_prefix)
 {
     if (!a_path.starts_with('/') || !a_prefix.starts_with('/')) {
-        // FIXME: This should probably VERIFY or return an Optional<DeprecatedString>.
+        // FIXME: This should probably VERIFY or return an Optional<ByteString>.
         return ""sv;
     }
 
@@ -186,7 +186,7 @@ DeprecatedString LexicalPath::relative_path(StringView a_path, StringView a_pref
             builder.append('/');
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 LexicalPath LexicalPath::append(StringView value) const
diff --git a/AK/LexicalPath.h b/AK/LexicalPath.h
index 35793aea753..44640309b43 100644
--- a/AK/LexicalPath.h
+++ b/AK/LexicalPath.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 
 // On Linux distros that use mlibc `basename` is defined as a macro that expands to `__mlibc_gnu_basename` or `__mlibc_gnu_basename_c`, so we undefine it.
@@ -24,10 +24,10 @@ public:
         Yes
     };
 
-    explicit LexicalPath(DeprecatedString);
+    explicit LexicalPath(ByteString);
 
     bool is_absolute() const { return !m_string.is_empty() && m_string[0] == '/'; }
-    DeprecatedString const& string() const { return m_string; }
+    ByteString const& string() const { return m_string; }
 
     StringView dirname() const { return m_dirname; }
     StringView basename(StripExtension s = StripExtension::No) const { return s == StripExtension::No ? m_basename : m_basename.substring_view(0, m_basename.length() - m_extension.length() - 1); }
@@ -35,7 +35,7 @@ public:
     StringView extension() const { return m_extension; }
 
     Vector<StringView> const& parts_view() const { return m_parts; }
-    [[nodiscard]] Vector<DeprecatedString> parts() const;
+    [[nodiscard]] Vector<ByteString> parts() const;
 
     bool has_extension(StringView) const;
     bool is_child_of(LexicalPath const& possible_parent) const;
@@ -44,9 +44,9 @@ public:
     [[nodiscard]] LexicalPath prepend(StringView) const;
     [[nodiscard]] LexicalPath parent() const;
 
-    [[nodiscard]] static DeprecatedString canonicalized_path(DeprecatedString);
-    [[nodiscard]] static DeprecatedString absolute_path(DeprecatedString dir_path, DeprecatedString target);
-    [[nodiscard]] static DeprecatedString relative_path(StringView absolute_path, StringView prefix);
+    [[nodiscard]] static ByteString canonicalized_path(ByteString);
+    [[nodiscard]] static ByteString absolute_path(ByteString dir_path, ByteString target);
+    [[nodiscard]] static ByteString relative_path(StringView absolute_path, StringView prefix);
 
     template<typename... S>
     [[nodiscard]] static LexicalPath join(StringView first, S&&... rest)
@@ -55,28 +55,28 @@ public:
         builder.append(first);
         ((builder.append('/'), builder.append(forward<S>(rest))), ...);
 
-        return LexicalPath { builder.to_deprecated_string() };
+        return LexicalPath { builder.to_byte_string() };
     }
 
-    [[nodiscard]] static DeprecatedString dirname(DeprecatedString path)
+    [[nodiscard]] static ByteString dirname(ByteString path)
     {
         auto lexical_path = LexicalPath(move(path));
         return lexical_path.dirname();
     }
 
-    [[nodiscard]] static DeprecatedString basename(DeprecatedString path, StripExtension s = StripExtension::No)
+    [[nodiscard]] static ByteString basename(ByteString path, StripExtension s = StripExtension::No)
     {
         auto lexical_path = LexicalPath(move(path));
         return lexical_path.basename(s);
     }
 
-    [[nodiscard]] static DeprecatedString title(DeprecatedString path)
+    [[nodiscard]] static ByteString title(ByteString path)
     {
         auto lexical_path = LexicalPath(move(path));
         return lexical_path.title();
     }
 
-    [[nodiscard]] static DeprecatedString extension(DeprecatedString path)
+    [[nodiscard]] static ByteString extension(ByteString path)
     {
         auto lexical_path = LexicalPath(move(path));
         return lexical_path.extension();
@@ -84,7 +84,7 @@ public:
 
 private:
     Vector<StringView> m_parts;
-    DeprecatedString m_string;
+    ByteString m_string;
     StringView m_dirname;
     StringView m_basename;
     StringView m_title;
diff --git a/AK/MACAddress.h b/AK/MACAddress.h
index cd90c83fe34..b948575e5ad 100644
--- a/AK/MACAddress.h
+++ b/AK/MACAddress.h
@@ -15,7 +15,7 @@
 #ifdef KERNEL
 #    include <Kernel/Library/KString.h>
 #else
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 class [[gnu::packed]] MACAddress {
@@ -64,9 +64,9 @@ public:
         return Kernel::KString::formatted("{:02x}:{:02x}:{:02x}:{:02x}:{:02x}:{:02x}", m_data[0], m_data[1], m_data[2], m_data[3], m_data[4], m_data[5]);
     }
 #else
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
-        return DeprecatedString::formatted("{:02x}:{:02x}:{:02x}:{:02x}:{:02x}:{:02x}", m_data[0], m_data[1], m_data[2], m_data[3], m_data[4], m_data[5]);
+        return ByteString::formatted("{:02x}:{:02x}:{:02x}:{:02x}:{:02x}:{:02x}", m_data[0], m_data[1], m_data[2], m_data[3], m_data[4], m_data[5]);
     }
 #endif
 
diff --git a/AK/NumberFormat.cpp b/AK/NumberFormat.cpp
index bb60ca4c74c..3841f5ce339 100644
--- a/AK/NumberFormat.cpp
+++ b/AK/NumberFormat.cpp
@@ -5,7 +5,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NumberFormat.h>
 #include <AK/NumericLimits.h>
 #include <AK/StringView.h>
@@ -13,7 +13,7 @@
 namespace AK {
 
 // FIXME: Remove this hackery once printf() supports floats.
-static DeprecatedString number_string_with_one_decimal(u64 number, u64 unit, StringView suffix, UseThousandsSeparator use_thousands_separator)
+static ByteString number_string_with_one_decimal(u64 number, u64 unit, StringView suffix, UseThousandsSeparator use_thousands_separator)
 {
     constexpr auto max_unit_size = NumericLimits<u64>::max() / 10;
     VERIFY(unit < max_unit_size);
@@ -21,25 +21,25 @@ static DeprecatedString number_string_with_one_decimal(u64 number, u64 unit, Str
     auto integer_part = number / unit;
     auto decimal_part = (number % unit) * 10 / unit;
     if (use_thousands_separator == UseThousandsSeparator::Yes)
-        return DeprecatedString::formatted("{:'d}.{} {}", integer_part, decimal_part, suffix);
+        return ByteString::formatted("{:'d}.{} {}", integer_part, decimal_part, suffix);
 
-    return DeprecatedString::formatted("{}.{} {}", integer_part, decimal_part, suffix);
+    return ByteString::formatted("{}.{} {}", integer_part, decimal_part, suffix);
 }
 
-DeprecatedString human_readable_quantity(u64 quantity, HumanReadableBasedOn based_on, StringView unit, UseThousandsSeparator use_thousands_separator)
+ByteString human_readable_quantity(u64 quantity, HumanReadableBasedOn based_on, StringView unit, UseThousandsSeparator use_thousands_separator)
 {
     u64 size_of_unit = based_on == HumanReadableBasedOn::Base2 ? 1024 : 1000;
     constexpr auto unit_prefixes = AK::Array { "", "K", "M", "G", "T", "P", "E" };
     auto full_unit_suffix = [&](int index) {
         auto binary_infix = (based_on == HumanReadableBasedOn::Base2 && index != 0) ? "i"sv : ""sv;
-        return DeprecatedString::formatted("{}{}{}",
+        return ByteString::formatted("{}{}{}",
             unit_prefixes[index], binary_infix, unit);
     };
 
     auto size_of_current_unit = size_of_unit;
 
     if (quantity < size_of_unit)
-        return DeprecatedString::formatted("{} {}", quantity, full_unit_suffix(0));
+        return ByteString::formatted("{} {}", quantity, full_unit_suffix(0));
 
     for (size_t i = 1; i < unit_prefixes.size() - 1; i++) {
         auto suffix = full_unit_suffix(i);
@@ -54,28 +54,28 @@ DeprecatedString human_readable_quantity(u64 quantity, HumanReadableBasedOn base
         size_of_current_unit, full_unit_suffix(unit_prefixes.size() - 1), use_thousands_separator);
 }
 
-DeprecatedString human_readable_size(u64 size, HumanReadableBasedOn based_on, UseThousandsSeparator use_thousands_separator)
+ByteString human_readable_size(u64 size, HumanReadableBasedOn based_on, UseThousandsSeparator use_thousands_separator)
 {
     return human_readable_quantity(size, based_on, "B"sv, use_thousands_separator);
 }
 
-DeprecatedString human_readable_size_long(u64 size, UseThousandsSeparator use_thousands_separator)
+ByteString human_readable_size_long(u64 size, UseThousandsSeparator use_thousands_separator)
 {
     if (size < 1 * KiB) {
         if (use_thousands_separator == UseThousandsSeparator::Yes)
-            return DeprecatedString::formatted("{:'d} bytes", size);
+            return ByteString::formatted("{:'d} bytes", size);
 
-        return DeprecatedString::formatted("{} bytes", size);
+        return ByteString::formatted("{} bytes", size);
     }
 
     auto human_readable_size_string = human_readable_size(size, HumanReadableBasedOn::Base2, use_thousands_separator);
     if (use_thousands_separator == UseThousandsSeparator::Yes)
-        return DeprecatedString::formatted("{} ({:'d} bytes)", human_readable_size_string, size);
+        return ByteString::formatted("{} ({:'d} bytes)", human_readable_size_string, size);
 
-    return DeprecatedString::formatted("{} ({} bytes)", human_readable_size_string, size);
+    return ByteString::formatted("{} ({} bytes)", human_readable_size_string, size);
 }
 
-DeprecatedString human_readable_time(i64 time_in_seconds)
+ByteString human_readable_time(i64 time_in_seconds)
 {
     auto days = time_in_seconds / 86400;
     time_in_seconds = time_in_seconds % 86400;
@@ -99,10 +99,10 @@ DeprecatedString human_readable_time(i64 time_in_seconds)
 
     builder.appendff("{} second{}", time_in_seconds, time_in_seconds == 1 ? "" : "s");
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString human_readable_digital_time(i64 time_in_seconds)
+ByteString human_readable_digital_time(i64 time_in_seconds)
 {
     auto hours = time_in_seconds / 3600;
     time_in_seconds = time_in_seconds % 3600;
@@ -117,7 +117,7 @@ DeprecatedString human_readable_digital_time(i64 time_in_seconds)
     builder.appendff("{:02}:", minutes);
     builder.appendff("{:02}", time_in_seconds);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/AK/NumberFormat.h b/AK/NumberFormat.h
index 72b4f6a17a4..fdb16d3a113 100644
--- a/AK/NumberFormat.h
+++ b/AK/NumberFormat.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 
 namespace AK {
 
@@ -20,12 +20,12 @@ enum class UseThousandsSeparator {
     No
 };
 
-DeprecatedString human_readable_size(u64 size, HumanReadableBasedOn based_on = HumanReadableBasedOn::Base2, UseThousandsSeparator use_thousands_separator = UseThousandsSeparator::No);
-DeprecatedString human_readable_quantity(u64 quantity, HumanReadableBasedOn based_on = HumanReadableBasedOn::Base2, StringView unit = "B"sv, UseThousandsSeparator use_thousands_separator = UseThousandsSeparator::No);
+ByteString human_readable_size(u64 size, HumanReadableBasedOn based_on = HumanReadableBasedOn::Base2, UseThousandsSeparator use_thousands_separator = UseThousandsSeparator::No);
+ByteString human_readable_quantity(u64 quantity, HumanReadableBasedOn based_on = HumanReadableBasedOn::Base2, StringView unit = "B"sv, UseThousandsSeparator use_thousands_separator = UseThousandsSeparator::No);
 
-DeprecatedString human_readable_size_long(u64 size, UseThousandsSeparator use_thousands_separator = UseThousandsSeparator::No);
-DeprecatedString human_readable_time(i64 time_in_seconds);
-DeprecatedString human_readable_digital_time(i64 time_in_seconds);
+ByteString human_readable_size_long(u64 size, UseThousandsSeparator use_thousands_separator = UseThousandsSeparator::No);
+ByteString human_readable_time(i64 time_in_seconds);
+ByteString human_readable_digital_time(i64 time_in_seconds);
 
 }
 
diff --git a/AK/ReverseIterator.h b/AK/ReverseIterator.h
index 5aa0e714c39..c3553758ac1 100644
--- a/AK/ReverseIterator.h
+++ b/AK/ReverseIterator.h
@@ -66,7 +66,7 @@ private:
     static constexpr SimpleReverseIterator rbegin(Container& container)
     {
         using RawContainerType = RemoveCV<Container>;
-        if constexpr (IsSame<StringView, RawContainerType> || IsSame<DeprecatedString, RawContainerType>)
+        if constexpr (IsSame<StringView, RawContainerType> || IsSame<ByteString, RawContainerType>)
             return { container, static_cast<int>(container.length()) - 1 };
         else
             return { container, static_cast<int>(container.size()) - 1 };
diff --git a/AK/ScopeLogger.h b/AK/ScopeLogger.h
index 92b3699d5dc..5b6390aebc1 100644
--- a/AK/ScopeLogger.h
+++ b/AK/ScopeLogger.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/SourceLocation.h>
 #include <AK/StringBuilder.h>
 
@@ -24,9 +24,9 @@ public:
         for (auto indent = m_depth++; indent > 0; indent--)
             sb.append(' ');
         if (m_extra.is_empty())
-            dbgln("\033[1;{}m{}entering {}\033[0m", m_depth % 8 + 30, sb.to_deprecated_string(), m_location);
+            dbgln("\033[1;{}m{}entering {}\033[0m", m_depth % 8 + 30, sb.to_byte_string(), m_location);
         else
-            dbgln("\033[1;{}m{}entering {}\033[0m ({})", m_depth % 8 + 30, sb.to_deprecated_string(), m_location, m_extra);
+            dbgln("\033[1;{}m{}entering {}\033[0m ({})", m_depth % 8 + 30, sb.to_byte_string(), m_location, m_extra);
     }
 
     ScopeLogger(SourceLocation location = SourceLocation::current())
@@ -42,15 +42,15 @@ public:
         for (auto indent = --m_depth; indent > 0; indent--)
             sb.append(' ');
         if (m_extra.is_empty())
-            dbgln("\033[1;{}m{}leaving {}\033[0m", depth % 8 + 30, sb.to_deprecated_string(), m_location);
+            dbgln("\033[1;{}m{}leaving {}\033[0m", depth % 8 + 30, sb.to_byte_string(), m_location);
         else
-            dbgln("\033[1;{}m{}leaving {}\033[0m ({})", depth % 8 + 30, sb.to_deprecated_string(), m_location, m_extra);
+            dbgln("\033[1;{}m{}leaving {}\033[0m ({})", depth % 8 + 30, sb.to_byte_string(), m_location, m_extra);
     }
 
 private:
     static inline size_t m_depth = 0;
     SourceLocation m_location;
-    DeprecatedString m_extra;
+    ByteString m_extra;
 };
 
 template<>
diff --git a/AK/SourceGenerator.h b/AK/SourceGenerator.h
index 000410ac7a6..7a2c0e444ae 100644
--- a/AK/SourceGenerator.h
+++ b/AK/SourceGenerator.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/GenericLexer.h>
 #include <AK/HashMap.h>
 #include <AK/String.h>
@@ -116,12 +116,12 @@ public:
     }
 
     // FIXME: These are deprecated.
-    void set(StringView key, DeprecatedString value)
+    void set(StringView key, ByteString value)
     {
-        set(key, MUST(String::from_deprecated_string(value)));
+        set(key, MUST(String::from_byte_string(value)));
     }
     template<size_t N>
-    void set(char const (&key)[N], DeprecatedString value)
+    void set(char const (&key)[N], ByteString value)
     {
         set(StringView { key, N - 1 }, value);
     }
diff --git a/AK/String.cpp b/AK/String.cpp
index f6d7f2dc1f9..3fe5e088679 100644
--- a/AK/String.cpp
+++ b/AK/String.cpp
@@ -621,14 +621,14 @@ void String::did_create_fly_string(Badge<FlyString>) const
     m_data->set_fly_string(true);
 }
 
-DeprecatedString String::to_deprecated_string() const
+ByteString String::to_byte_string() const
 {
-    return DeprecatedString(bytes_as_string_view());
+    return ByteString(bytes_as_string_view());
 }
 
-ErrorOr<String> String::from_deprecated_string(DeprecatedString const& deprecated_string)
+ErrorOr<String> String::from_byte_string(ByteString const& byte_string)
 {
-    return String::from_utf8(deprecated_string.view());
+    return String::from_utf8(byte_string.view());
 }
 
 bool String::equals_ignoring_ascii_case(StringView other) const
diff --git a/AK/String.h b/AK/String.h
index e54b7fb4f2c..f122160fb69 100644
--- a/AK/String.h
+++ b/AK/String.h
@@ -67,7 +67,7 @@ public:
     // Creates a new String from a sequence of UTF-8 encoded code points.
     static ErrorOr<String> from_utf8(StringView);
     template<typename T>
-    requires(IsOneOf<RemoveCVReference<T>, DeprecatedString, DeprecatedFlyString, FlyString, String>)
+    requires(IsOneOf<RemoveCVReference<T>, ByteString, DeprecatedFlyString, FlyString, String>)
     static ErrorOr<String> from_utf8(T&&) = delete;
 
     // Creates a new String by reading byte_count bytes from a UTF-8 encoded Stream.
@@ -221,11 +221,11 @@ public:
     void did_create_fly_string(Badge<FlyString>) const;
 
     // FIXME: Remove these once all code has been ported to String
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
-    static ErrorOr<String> from_deprecated_string(DeprecatedString const&);
+    [[nodiscard]] ByteString to_byte_string() const;
+    static ErrorOr<String> from_byte_string(ByteString const&);
     template<typename T>
     requires(IsSame<RemoveCVReference<T>, StringView>)
-    static ErrorOr<String> from_deprecated_string(T&&) = delete;
+    static ErrorOr<String> from_byte_string(T&&) = delete;
 
 private:
     // NOTE: If the least significant bit of the pointer is set, this is a short string.
diff --git a/AK/StringBuilder.cpp b/AK/StringBuilder.cpp
index 88b3f7fdb19..1db8dea923c 100644
--- a/AK/StringBuilder.cpp
+++ b/AK/StringBuilder.cpp
@@ -15,7 +15,7 @@
 #include <AK/Utf32View.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #    include <AK/FlyString.h>
 #    include <AK/Utf16View.h>
 #endif
@@ -144,11 +144,11 @@ ErrorOr<ByteBuffer> StringBuilder::to_byte_buffer() const
 }
 
 #ifndef KERNEL
-DeprecatedString StringBuilder::to_deprecated_string() const
+ByteString StringBuilder::to_byte_string() const
 {
     if (is_empty())
-        return DeprecatedString::empty();
-    return DeprecatedString((char const*)data(), length());
+        return ByteString::empty();
+    return ByteString((char const*)data(), length());
 }
 
 ErrorOr<String> StringBuilder::to_string() const
diff --git a/AK/StringBuilder.h b/AK/StringBuilder.h
index 8632d838a7a..8d2e09a48fa 100644
--- a/AK/StringBuilder.h
+++ b/AK/StringBuilder.h
@@ -18,7 +18,7 @@ class StringBuilder {
 public:
     static constexpr size_t inline_capacity = 256;
 
-    using OutputType = DeprecatedString;
+    using OutputType = ByteString;
 
     static ErrorOr<StringBuilder> create(size_t initial_capacity = inline_capacity);
 
@@ -70,7 +70,7 @@ public:
     }
 
 #ifndef KERNEL
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
+    [[nodiscard]] ByteString to_byte_string() const;
 #endif
 
     ErrorOr<String> to_string() const;
diff --git a/AK/StringUtils.cpp b/AK/StringUtils.cpp
index ab087a43580..814db99776c 100644
--- a/AK/StringUtils.cpp
+++ b/AK/StringUtils.cpp
@@ -17,7 +17,7 @@
 #ifdef KERNEL
 #    include <Kernel/Library/StdLib.h>
 #else
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #    include <AK/FloatingPointStringConversions.h>
 #    include <string.h>
 #endif
@@ -465,7 +465,7 @@ Optional<size_t> find_any_of(StringView haystack, StringView needles, SearchDire
 }
 
 #ifndef KERNEL
-DeprecatedString to_snakecase(StringView str)
+ByteString to_snakecase(StringView str)
 {
     auto should_insert_underscore = [&](auto i, auto current_char) {
         if (i == 0)
@@ -488,10 +488,10 @@ DeprecatedString to_snakecase(StringView str)
             builder.append('_');
         builder.append_as_lowercase(ch);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString to_titlecase(StringView str)
+ByteString to_titlecase(StringView str)
 {
     StringBuilder builder;
     bool next_is_upper = true;
@@ -504,10 +504,10 @@ DeprecatedString to_titlecase(StringView str)
         next_is_upper = ch == ' ';
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString invert_case(StringView str)
+ByteString invert_case(StringView str)
 {
     StringBuilder builder(str.length());
 
@@ -518,10 +518,10 @@ DeprecatedString invert_case(StringView str)
             builder.append(to_ascii_lowercase(ch));
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString replace(StringView str, StringView needle, StringView replacement, ReplaceMode replace_mode)
+ByteString replace(StringView str, StringView needle, StringView replacement, ReplaceMode replace_mode)
 {
     if (str.is_empty())
         return str;
@@ -546,7 +546,7 @@ DeprecatedString replace(StringView str, StringView needle, StringView replaceme
         last_position = position + needle.length();
     }
     replaced_string.append(str.substring_view(last_position, str.length() - last_position));
-    return replaced_string.to_deprecated_string();
+    return replaced_string.to_byte_string();
 }
 
 ErrorOr<String> replace(String const& haystack, StringView needle, StringView replacement, ReplaceMode replace_mode)
diff --git a/AK/StringUtils.h b/AK/StringUtils.h
index 1bc4b865bdb..1f29fdff748 100644
--- a/AK/StringUtils.h
+++ b/AK/StringUtils.h
@@ -106,11 +106,11 @@ enum class SearchDirection {
 };
 Optional<size_t> find_any_of(StringView haystack, StringView needles, SearchDirection);
 
-DeprecatedString to_snakecase(StringView);
-DeprecatedString to_titlecase(StringView);
-DeprecatedString invert_case(StringView);
+ByteString to_snakecase(StringView);
+ByteString to_titlecase(StringView);
+ByteString invert_case(StringView);
 
-DeprecatedString replace(StringView, StringView needle, StringView replacement, ReplaceMode);
+ByteString replace(StringView, StringView needle, StringView replacement, ReplaceMode);
 ErrorOr<String> replace(String const&, StringView needle, StringView replacement, ReplaceMode);
 
 size_t count(StringView, StringView needle);
diff --git a/AK/StringView.cpp b/AK/StringView.cpp
index 92ffe4fe94c..f5440c716dd 100644
--- a/AK/StringView.cpp
+++ b/AK/StringView.cpp
@@ -13,8 +13,8 @@
 #include <AK/Vector.h>
 
 #ifndef KERNEL
+#    include <AK/ByteString.h>
 #    include <AK/DeprecatedFlyString.h>
-#    include <AK/DeprecatedString.h>
 #    include <AK/FlyString.h>
 #    include <AK/String.h>
 #endif
@@ -34,7 +34,7 @@ StringView::StringView(FlyString const& string)
 {
 }
 
-StringView::StringView(DeprecatedString const& string)
+StringView::StringView(ByteString const& string)
     : m_characters(string.characters())
     , m_length(string.length())
 {
@@ -176,17 +176,17 @@ bool StringView::equals_ignoring_ascii_case(StringView other) const
 }
 
 #ifndef KERNEL
-DeprecatedString StringView::to_lowercase_string() const
+ByteString StringView::to_lowercase_string() const
 {
     return StringImpl::create_lowercased(characters_without_null_termination(), length()).release_nonnull();
 }
 
-DeprecatedString StringView::to_uppercase_string() const
+ByteString StringView::to_uppercase_string() const
 {
     return StringImpl::create_uppercased(characters_without_null_termination(), length()).release_nonnull();
 }
 
-DeprecatedString StringView::to_titlecase_string() const
+ByteString StringView::to_titlecase_string() const
 {
     return StringUtils::to_titlecase(*this);
 }
@@ -257,14 +257,14 @@ Optional<float> StringView::to_float(TrimWhitespace trim_whitespace) const
     return StringUtils::convert_to_floating_point<float>(*this, trim_whitespace);
 }
 
-bool StringView::operator==(DeprecatedString const& string) const
+bool StringView::operator==(ByteString const& string) const
 {
     return *this == string.view();
 }
 
-DeprecatedString StringView::to_deprecated_string() const { return DeprecatedString { *this }; }
+ByteString StringView::to_byte_string() const { return ByteString { *this }; }
 
-DeprecatedString StringView::replace(StringView needle, StringView replacement, ReplaceMode replace_mode) const
+ByteString StringView::replace(StringView needle, StringView replacement, ReplaceMode replace_mode) const
 {
     return StringUtils::replace(*this, needle, replacement, replace_mode);
 }
diff --git a/AK/StringView.h b/AK/StringView.h
index 94ac28c36a2..ff9cc8068d8 100644
--- a/AK/StringView.h
+++ b/AK/StringView.h
@@ -50,7 +50,7 @@ public:
 #ifndef KERNEL
     StringView(String const&);
     StringView(FlyString const&);
-    StringView(DeprecatedString const&);
+    StringView(ByteString const&);
     StringView(DeprecatedFlyString const&);
 #endif
 
@@ -58,11 +58,11 @@ public:
 #ifndef KERNEL
     explicit StringView(String&&) = delete;
     explicit StringView(FlyString&&) = delete;
-    explicit StringView(DeprecatedString&&) = delete;
+    explicit StringView(ByteString&&) = delete;
     explicit StringView(DeprecatedFlyString&&) = delete;
 #endif
 
-    template<OneOf<String, FlyString, DeprecatedString, DeprecatedFlyString, ByteBuffer> StringType>
+    template<OneOf<String, FlyString, ByteString, DeprecatedFlyString, ByteBuffer> StringType>
     StringView& operator=(StringType&&) = delete;
 
     [[nodiscard]] constexpr bool is_null() const
@@ -110,9 +110,9 @@ public:
     [[nodiscard]] StringView trim_whitespace(TrimMode mode = TrimMode::Both) const { return StringUtils::trim_whitespace(*this, mode); }
 
 #ifndef KERNEL
-    [[nodiscard]] DeprecatedString to_lowercase_string() const;
-    [[nodiscard]] DeprecatedString to_uppercase_string() const;
-    [[nodiscard]] DeprecatedString to_titlecase_string() const;
+    [[nodiscard]] ByteString to_lowercase_string() const;
+    [[nodiscard]] ByteString to_uppercase_string() const;
+    [[nodiscard]] ByteString to_titlecase_string() const;
 #endif
 
     [[nodiscard]] Optional<size_t> find(char needle, size_t start = 0) const
@@ -272,7 +272,7 @@ public:
     }
 
 #ifndef KERNEL
-    bool operator==(DeprecatedString const&) const;
+    bool operator==(ByteString const&) const;
 #endif
 
     [[nodiscard]] constexpr int compare(StringView other) const
@@ -314,7 +314,7 @@ public:
     constexpr bool operator>=(StringView other) const { return compare(other) >= 0; }
 
 #ifndef KERNEL
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
+    [[nodiscard]] ByteString to_byte_string() const;
 #endif
 
     [[nodiscard]] bool is_whitespace() const
@@ -323,7 +323,7 @@ public:
     }
 
 #ifndef KERNEL
-    [[nodiscard]] DeprecatedString replace(StringView needle, StringView replacement, ReplaceMode) const;
+    [[nodiscard]] ByteString replace(StringView needle, StringView replacement, ReplaceMode) const;
 #endif
     [[nodiscard]] size_t count(StringView needle) const
     {
@@ -354,7 +354,7 @@ public:
     }
 
 private:
-    friend class DeprecatedString;
+    friend class ByteString;
     char const* m_characters { nullptr };
     size_t m_length { 0 };
 };
diff --git a/AK/URL.cpp b/AK/URL.cpp
index 6f1019973e2..ec40ca2cd98 100644
--- a/AK/URL.cpp
+++ b/AK/URL.cpp
@@ -38,21 +38,21 @@ URL URL::complete_url(StringView relative_url) const
 
 ErrorOr<String> URL::username() const
 {
-    return String::from_deprecated_string(percent_decode(m_username));
+    return String::from_byte_string(percent_decode(m_username));
 }
 
 ErrorOr<String> URL::password() const
 {
-    return String::from_deprecated_string(percent_decode(m_password));
+    return String::from_byte_string(percent_decode(m_password));
 }
 
-DeprecatedString URL::path_segment_at_index(size_t index) const
+ByteString URL::path_segment_at_index(size_t index) const
 {
     VERIFY(index < path_segment_count());
     return percent_decode(m_paths[index]);
 }
 
-DeprecatedString URL::basename() const
+ByteString URL::basename() const
 {
     if (!m_valid)
         return {};
@@ -72,7 +72,7 @@ void URL::set_scheme(String scheme)
 ErrorOr<void> URL::set_username(StringView username)
 {
     // To set the username given a url and username, set url’s username to the result of running UTF-8 percent-encode on username using the userinfo percent-encode set.
-    m_username = TRY(String::from_deprecated_string(percent_encode(username, PercentEncodeSet::Userinfo)));
+    m_username = TRY(String::from_byte_string(percent_encode(username, PercentEncodeSet::Userinfo)));
     m_valid = compute_validity();
     return {};
 }
@@ -81,7 +81,7 @@ ErrorOr<void> URL::set_username(StringView username)
 ErrorOr<void> URL::set_password(StringView password)
 {
     // To set the password given a url and password, set url’s password to the result of running UTF-8 percent-encode on password using the userinfo percent-encode set.
-    m_password = TRY(String::from_deprecated_string(percent_encode(password, PercentEncodeSet::Userinfo)));
+    m_password = TRY(String::from_byte_string(percent_encode(password, PercentEncodeSet::Userinfo)));
     m_valid = compute_validity();
     return {};
 }
@@ -108,18 +108,18 @@ void URL::set_port(Optional<u16> port)
     m_valid = compute_validity();
 }
 
-void URL::set_paths(Vector<DeprecatedString> const& paths)
+void URL::set_paths(Vector<ByteString> const& paths)
 {
     m_paths.clear_with_capacity();
     m_paths.ensure_capacity(paths.size());
     for (auto const& segment : paths)
-        m_paths.unchecked_append(String::from_deprecated_string(percent_encode(segment, PercentEncodeSet::Path)).release_value_but_fixme_should_propagate_errors());
+        m_paths.unchecked_append(String::from_byte_string(percent_encode(segment, PercentEncodeSet::Path)).release_value_but_fixme_should_propagate_errors());
     m_valid = compute_validity();
 }
 
 void URL::append_path(StringView path)
 {
-    m_paths.append(String::from_deprecated_string(percent_encode(path, PercentEncodeSet::Path)).release_value_but_fixme_should_propagate_errors());
+    m_paths.append(String::from_byte_string(percent_encode(path, PercentEncodeSet::Path)).release_value_but_fixme_should_propagate_errors());
 }
 
 // https://url.spec.whatwg.org/#cannot-have-a-username-password-port
@@ -182,7 +182,7 @@ Optional<u16> URL::default_port_for_scheme(StringView scheme)
     return {};
 }
 
-URL URL::create_with_file_scheme(DeprecatedString const& path, DeprecatedString const& fragment, DeprecatedString const& hostname)
+URL URL::create_with_file_scheme(ByteString const& path, ByteString const& fragment, ByteString const& hostname)
 {
     LexicalPath lexical_path(path);
     if (!lexical_path.is_absolute())
@@ -190,38 +190,38 @@ URL URL::create_with_file_scheme(DeprecatedString const& path, DeprecatedString
 
     URL url;
     url.set_scheme("file"_string);
-    url.set_host(hostname == "localhost" ? String {} : String::from_deprecated_string(hostname).release_value_but_fixme_should_propagate_errors());
+    url.set_host(hostname == "localhost" ? String {} : String::from_byte_string(hostname).release_value_but_fixme_should_propagate_errors());
     url.set_paths(lexical_path.parts());
     if (path.ends_with('/'))
         url.append_slash();
     if (!fragment.is_empty())
-        url.set_fragment(String::from_deprecated_string(fragment).release_value_but_fixme_should_propagate_errors());
+        url.set_fragment(String::from_byte_string(fragment).release_value_but_fixme_should_propagate_errors());
     return url;
 }
 
-URL URL::create_with_help_scheme(DeprecatedString const& path, DeprecatedString const& fragment, DeprecatedString const& hostname)
+URL URL::create_with_help_scheme(ByteString const& path, ByteString const& fragment, ByteString const& hostname)
 {
     LexicalPath lexical_path(path);
 
     URL url;
     url.set_scheme("help"_string);
-    url.set_host(hostname == "localhost" ? String {} : String::from_deprecated_string(hostname).release_value_but_fixme_should_propagate_errors());
+    url.set_host(hostname == "localhost" ? String {} : String::from_byte_string(hostname).release_value_but_fixme_should_propagate_errors());
 
     url.set_paths(lexical_path.parts());
     if (path.ends_with('/'))
         url.append_slash();
     if (!fragment.is_empty())
-        url.set_fragment(String::from_deprecated_string(fragment).release_value_but_fixme_should_propagate_errors());
+        url.set_fragment(String::from_byte_string(fragment).release_value_but_fixme_should_propagate_errors());
     return url;
 }
 
-URL URL::create_with_url_or_path(DeprecatedString const& url_or_path)
+URL URL::create_with_url_or_path(ByteString const& url_or_path)
 {
     URL url = url_or_path;
     if (url.is_valid())
         return url;
 
-    DeprecatedString path = LexicalPath::canonicalized_path(url_or_path);
+    ByteString path = LexicalPath::canonicalized_path(url_or_path);
     return URL::create_with_file_scheme(path);
 }
 
@@ -237,7 +237,7 @@ URL URL::create_with_data(StringView mime_type, StringView payload, bool is_base
         builder.append(";base64"sv);
     builder.append(',');
     builder.append(payload);
-    url.set_paths({ builder.to_deprecated_string() });
+    url.set_paths({ builder.to_byte_string() });
     return url;
 }
 
@@ -248,12 +248,12 @@ bool URL::is_special_scheme(StringView scheme)
 }
 
 // https://url.spec.whatwg.org/#url-path-serializer
-DeprecatedString URL::serialize_path(ApplyPercentDecoding apply_percent_decoding) const
+ByteString URL::serialize_path(ApplyPercentDecoding apply_percent_decoding) const
 {
     // 1. If url has an opaque path, then return url’s path.
     // FIXME: Reimplement this step once we modernize the URL implementation to meet the spec.
     if (cannot_be_a_base_url())
-        return m_paths[0].to_deprecated_string();
+        return m_paths[0].to_byte_string();
 
     // 2. Let output be the empty string.
     StringBuilder output;
@@ -261,15 +261,15 @@ DeprecatedString URL::serialize_path(ApplyPercentDecoding apply_percent_decoding
     // 3. For each segment of url’s path: append U+002F (/) followed by segment to output.
     for (auto const& segment : m_paths) {
         output.append('/');
-        output.append(apply_percent_decoding == ApplyPercentDecoding::Yes ? percent_decode(segment) : segment.to_deprecated_string());
+        output.append(apply_percent_decoding == ApplyPercentDecoding::Yes ? percent_decode(segment) : segment.to_byte_string());
     }
 
     // 4. Return output.
-    return output.to_deprecated_string();
+    return output.to_byte_string();
 }
 
 // https://url.spec.whatwg.org/#concept-url-serializer
-DeprecatedString URL::serialize(ExcludeFragment exclude_fragment) const
+ByteString URL::serialize(ExcludeFragment exclude_fragment) const
 {
     // 1. Let output be url’s scheme and U+003A (:) concatenated.
     StringBuilder output;
@@ -331,14 +331,14 @@ DeprecatedString URL::serialize(ExcludeFragment exclude_fragment) const
     }
 
     // 7. Return output.
-    return output.to_deprecated_string();
+    return output.to_byte_string();
 }
 
 // https://url.spec.whatwg.org/#url-rendering
 // NOTE: This does e.g. not display credentials.
 // FIXME: Parts of the URL other than the host should have their sequences of percent-encoded bytes replaced with code points
 //        resulting from percent-decoding those sequences converted to bytes, unless that renders those sequences invisible.
-DeprecatedString URL::serialize_for_display() const
+ByteString URL::serialize_for_display() const
 {
     VERIFY(m_valid);
 
@@ -374,17 +374,17 @@ DeprecatedString URL::serialize_for_display() const
         builder.append(*m_fragment);
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 ErrorOr<String> URL::to_string() const
 {
-    return String::from_deprecated_string(serialize());
+    return String::from_byte_string(serialize());
 }
 
 // https://html.spec.whatwg.org/multipage/origin.html#ascii-serialisation-of-an-origin
 // https://url.spec.whatwg.org/#concept-url-origin
-DeprecatedString URL::serialize_origin() const
+ByteString URL::serialize_origin() const
 {
     VERIFY(m_valid);
 
@@ -407,7 +407,7 @@ DeprecatedString URL::serialize_origin() const
     builder.append(serialized_host().release_value_but_fixme_should_propagate_errors());
     if (m_port.has_value())
         builder.appendff(":{}", *m_port);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 bool URL::equals(URL const& other, ExcludeFragment exclude_fragments) const
@@ -544,7 +544,7 @@ void URL::append_percent_encoded_if_necessary(StringBuilder& builder, u32 code_p
         builder.append_code_point(code_point);
 }
 
-DeprecatedString URL::percent_encode(StringView input, URL::PercentEncodeSet set, SpaceAsPlus space_as_plus)
+ByteString URL::percent_encode(StringView input, URL::PercentEncodeSet set, SpaceAsPlus space_as_plus)
 {
     StringBuilder builder;
     for (auto code_point : Utf8View(input)) {
@@ -553,10 +553,10 @@ DeprecatedString URL::percent_encode(StringView input, URL::PercentEncodeSet set
         else
             append_percent_encoded_if_necessary(builder, code_point, set);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString URL::percent_decode(StringView input)
+ByteString URL::percent_decode(StringView input)
 {
     if (!input.contains('%'))
         return input;
@@ -575,7 +575,7 @@ DeprecatedString URL::percent_decode(StringView input)
             builder.append(byte);
         }
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/AK/URL.h b/AK/URL.h
index 951297a738c..2aeee6365ff 100644
--- a/AK/URL.h
+++ b/AK/URL.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/String.h>
 #include <AK/StringView.h>
 #include <AK/Vector.h>
@@ -45,7 +45,7 @@ public:
 
     URL() = default;
     URL(StringView);
-    URL(DeprecatedString const& string)
+    URL(ByteString const& string)
         : URL(string.view())
     {
     }
@@ -77,11 +77,11 @@ public:
     ErrorOr<String> password() const;
     Host const& host() const { return m_host; }
     ErrorOr<String> serialized_host() const;
-    DeprecatedString basename() const;
+    ByteString basename() const;
     Optional<String> const& query() const { return m_query; }
     Optional<String> const& fragment() const { return m_fragment; }
     Optional<u16> port() const { return m_port; }
-    DeprecatedString path_segment_at_index(size_t index) const;
+    ByteString path_segment_at_index(size_t index) const;
     size_t path_segment_count() const { return m_paths.size(); }
 
     u16 port_or_default() const { return m_port.value_or(default_port_for_scheme(m_scheme).value_or(0)); }
@@ -96,7 +96,7 @@ public:
     ErrorOr<void> set_password(StringView);
     void set_host(Host);
     void set_port(Optional<u16>);
-    void set_paths(Vector<DeprecatedString> const&);
+    void set_paths(Vector<ByteString> const&);
     void set_query(Optional<String> query) { m_query = move(query); }
     void set_fragment(Optional<String> fragment) { m_fragment = move(fragment); }
     void set_cannot_be_a_base_url(bool value) { m_cannot_be_a_base_url = value; }
@@ -111,14 +111,14 @@ public:
         Yes,
         No
     };
-    DeprecatedString serialize_path(ApplyPercentDecoding = ApplyPercentDecoding::Yes) const;
-    DeprecatedString serialize(ExcludeFragment = ExcludeFragment::No) const;
-    DeprecatedString serialize_for_display() const;
-    DeprecatedString to_deprecated_string() const { return serialize(); }
+    ByteString serialize_path(ApplyPercentDecoding = ApplyPercentDecoding::Yes) const;
+    ByteString serialize(ExcludeFragment = ExcludeFragment::No) const;
+    ByteString serialize_for_display() const;
+    ByteString to_byte_string() const { return serialize(); }
     ErrorOr<String> to_string() const;
 
     // HTML origin
-    DeprecatedString serialize_origin() const;
+    ByteString serialize_origin() const;
 
     bool equals(URL const& other, ExcludeFragment = ExcludeFragment::No) const;
 
@@ -130,9 +130,9 @@ public:
     };
     ErrorOr<DataURL> process_data_url() const;
 
-    static URL create_with_url_or_path(DeprecatedString const&);
-    static URL create_with_file_scheme(DeprecatedString const& path, DeprecatedString const& fragment = {}, DeprecatedString const& hostname = {});
-    static URL create_with_help_scheme(DeprecatedString const& path, DeprecatedString const& fragment = {}, DeprecatedString const& hostname = {});
+    static URL create_with_url_or_path(ByteString const&);
+    static URL create_with_file_scheme(ByteString const& path, ByteString const& fragment = {}, ByteString const& hostname = {});
+    static URL create_with_help_scheme(ByteString const& path, ByteString const& fragment = {}, ByteString const& hostname = {});
     static URL create_with_data(StringView mime_type, StringView payload, bool is_base64 = false);
 
     static Optional<u16> default_port_for_scheme(StringView);
@@ -142,8 +142,8 @@ public:
         No,
         Yes,
     };
-    static DeprecatedString percent_encode(StringView input, PercentEncodeSet set = PercentEncodeSet::Userinfo, SpaceAsPlus = SpaceAsPlus::No);
-    static DeprecatedString percent_decode(StringView input);
+    static ByteString percent_encode(StringView input, PercentEncodeSet set = PercentEncodeSet::Userinfo, SpaceAsPlus = SpaceAsPlus::No);
+    static ByteString percent_decode(StringView input);
 
     bool operator==(URL const& other) const { return equals(other, ExcludeFragment::No); }
 
@@ -198,7 +198,7 @@ struct Formatter<URL> : Formatter<StringView> {
 
 template<>
 struct Traits<URL> : public DefaultTraits<URL> {
-    static unsigned hash(URL const& url) { return url.to_deprecated_string().hash(); }
+    static unsigned hash(URL const& url) { return url.to_byte_string().hash(); }
 };
 
 }
diff --git a/AK/URLParser.cpp b/AK/URLParser.cpp
index 8ab4e841ce1..700eb117ec7 100644
--- a/AK/URLParser.cpp
+++ b/AK/URLParser.cpp
@@ -5,9 +5,9 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/IntegralMath.h>
 #include <AK/Optional.h>
 #include <AK/SourceLocation.h>
@@ -57,7 +57,7 @@ static Optional<URL::Host> parse_opaque_host(StringView input)
     //       currently report validation errors, they are only useful for debugging efforts in the URL parsing code.
 
     // 4. Return the result of running UTF-8 percent-encode on input using the C0 control percent-encode set.
-    return String::from_deprecated_string(URL::percent_encode(input, URL::PercentEncodeSet::C0Control)).release_value_but_fixme_should_propagate_errors();
+    return String::from_byte_string(URL::percent_encode(input, URL::PercentEncodeSet::C0Control)).release_value_but_fixme_should_propagate_errors();
 }
 
 struct ParsedIPv4Number {
@@ -606,7 +606,7 @@ static Optional<URL::Host> parse_host(StringView input, bool is_opaque = false)
     // NOTE: This is handled in Unicode::create_unicode_url, to work around the fact that we can't call into LibUnicode here
     // FIXME: 5. Let asciiDomain be the result of running domain to ASCII with domain and false.
     // FIXME: 6. If asciiDomain is failure, then return failure.
-    auto ascii_domain_or_error = String::from_deprecated_string(domain);
+    auto ascii_domain_or_error = String::from_byte_string(domain);
     if (ascii_domain_or_error.is_error())
         return {};
 
@@ -792,7 +792,7 @@ URL URLParser::basic_parse(StringView raw_input, Optional<URL> const& base_url,
     if (start_index >= end_index)
         return {};
 
-    DeprecatedString processed_input = raw_input.substring_view(start_index, end_index - start_index);
+    ByteString processed_input = raw_input.substring_view(start_index, end_index - start_index);
 
     // 2. If input contains any ASCII tab or newline, invalid-URL-unit validation error.
     // 3. Remove all ASCII tab or newline from input.
@@ -1116,7 +1116,7 @@ URL URLParser::basic_parse(StringView raw_input, Optional<URL> const& base_url,
 
                 // 2. If atSignSeen is true, then prepend "%40" to buffer.
                 if (at_sign_seen) {
-                    auto content = buffer.to_deprecated_string();
+                    auto content = buffer.to_byte_string();
                     buffer.clear();
                     buffer.append("%40"sv);
                     buffer.append(content);
diff --git a/AK/Utf16View.cpp b/AK/Utf16View.cpp
index b3eb615c035..5c0b4c76005 100644
--- a/AK/Utf16View.cpp
+++ b/AK/Utf16View.cpp
@@ -81,9 +81,9 @@ u32 Utf16View::decode_surrogate_pair(u16 high_surrogate, u16 low_surrogate)
     return ((high_surrogate - high_surrogate_min) << 10) + (low_surrogate - low_surrogate_min) + first_supplementary_plane_code_point;
 }
 
-ErrorOr<DeprecatedString> Utf16View::to_deprecated_string(AllowInvalidCodeUnits allow_invalid_code_units) const
+ErrorOr<ByteString> Utf16View::to_byte_string(AllowInvalidCodeUnits allow_invalid_code_units) const
 {
-    return TRY(to_utf8(allow_invalid_code_units)).to_deprecated_string();
+    return TRY(to_utf8(allow_invalid_code_units)).to_byte_string();
 }
 
 ErrorOr<String> Utf16View::to_utf8(AllowInvalidCodeUnits allow_invalid_code_units) const
diff --git a/AK/Utf16View.h b/AK/Utf16View.h
index ed40af75637..c1323be9421 100644
--- a/AK/Utf16View.h
+++ b/AK/Utf16View.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Format.h>
 #include <AK/Forward.h>
@@ -78,7 +78,7 @@ public:
         No,
     };
 
-    ErrorOr<DeprecatedString> to_deprecated_string(AllowInvalidCodeUnits = AllowInvalidCodeUnits::No) const;
+    ErrorOr<ByteString> to_byte_string(AllowInvalidCodeUnits = AllowInvalidCodeUnits::No) const;
     ErrorOr<String> to_utf8(AllowInvalidCodeUnits = AllowInvalidCodeUnits::No) const;
 
     bool is_null() const { return m_code_units.is_null(); }
diff --git a/AK/Utf8View.h b/AK/Utf8View.h
index d7ae838dc71..0e1184401fb 100644
--- a/AK/Utf8View.h
+++ b/AK/Utf8View.h
@@ -12,7 +12,7 @@
 #include <AK/Types.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace AK {
@@ -72,12 +72,12 @@ public:
     }
 
 #ifndef KERNEL
-    explicit Utf8View(DeprecatedString& string)
+    explicit Utf8View(ByteString& string)
         : m_string(string.view())
     {
     }
 
-    explicit Utf8View(DeprecatedString&&) = delete;
+    explicit Utf8View(ByteString&&) = delete;
 #endif
 
     ~Utf8View() = default;
@@ -255,14 +255,14 @@ public:
         return Utf8View(m_string).byte_offset_of(m_it);
     }
 
-    DeprecatedStringCodePointIterator(DeprecatedString string)
+    DeprecatedStringCodePointIterator(ByteString string)
         : m_string(move(string))
         , m_it(Utf8View(m_string).begin())
     {
     }
 
 private:
-    DeprecatedString m_string;
+    ByteString m_string;
     Utf8CodePointIterator m_it;
 };
 #endif
diff --git a/Base/usr/share/man/man5/clipboard.md b/Base/usr/share/man/man5/clipboard.md
index 90d3ba0162e..d062274f472 100644
--- a/Base/usr/share/man/man5/clipboard.md
+++ b/Base/usr/share/man/man5/clipboard.md
@@ -5,17 +5,17 @@ clipboard - Data formats specific to Clipboard and drag & drop
 ## Clipboard
 
 The clipboard feature works through the Clipboard server, which generally acts as a global storage or three things:
-- a `DeprecatedString` mime type,
+- a `ByteString` mime type,
 - a (potentially large) block of data, shared as an anonymous file,
-- a `HashMap<DeprecatedString, DeprecatedString>` of arbitrary metadata, depending on the mime type.
+- a `HashMap<ByteString, ByteString>` of arbitrary metadata, depending on the mime type.
 
 See also [`Userland/Libraries/LibGUI/Clipboard.h`](../../../../../Userland/Libraries/LibGUI/Clipboard.h).
 
 ## Drag & drop
 
 In contrast to the clipboard, the drag & drop feature works through WindowServer, and a bouquet of data is transmitted:
-- a `[UTF8] DeprecatedString` to be displayed while dragging,
-- a `HashMap<DeprecatedString, ByteBuffer>` map that contains arbitrary data for a variety of possible mime types,
+- a `[UTF8] ByteString` to be displayed while dragging,
+- a `HashMap<ByteString, ByteBuffer>` map that contains arbitrary data for a variety of possible mime types,
 - a `Gfx::ShareableBitmap` to be displayed while dragging
 
 Drag & drop is most prominently supported by File Manager, Spreadsheet, and Terminal.
diff --git a/Base/usr/share/man/man5/ipc.md b/Base/usr/share/man/man5/ipc.md
index 12bea5d6fd2..eb61349becc 100644
--- a/Base/usr/share/man/man5/ipc.md
+++ b/Base/usr/share/man/man5/ipc.md
@@ -91,7 +91,7 @@ Start from defining an endpoint in the IPC file in `MyServer.ipc`.
 ```ipc
 endpoint MyServer
 {
-    SyncAPI(DeprecatedString text) => (i32 status)
+    SyncAPI(ByteString text) => (i32 status)
     AsyncAPI(i32 mode) =|
 }
 ```
@@ -102,7 +102,7 @@ Part of the generated C++ messages:
 class SyncAPI final : public IPC::Message {
 public:
     using ResponseType = SyncAPIResponse;
-    SyncAPI(const DeprecatedString& text) : m_text(text) {}
+    SyncAPI(const ByteString& text) : m_text(text) {}
     virtual ~SyncAPI() override {}
     static OwnPtr<SyncAPI> decode(...);
     virtual IPC::MessageBuffer encode(...) const override;
diff --git a/Documentation/StringFormatting.md b/Documentation/StringFormatting.md
index 33f6265f50f..ba494ce5660 100644
--- a/Documentation/StringFormatting.md
+++ b/Documentation/StringFormatting.md
@@ -1,6 +1,6 @@
 # String Formatting
 
-Many places in Serenity allow you to format strings, similar to `printf()`, for example `DeprecatedString::formatted()`
+Many places in Serenity allow you to format strings, similar to `printf()`, for example `ByteString::formatted()`
 , `StringBuilder::appendff()`, or `dbgln()`. These are checked at compile time to ensure the format string matches the
 number of parameters. The syntax is largely based on
 the [C++ `std::formatter` syntax](https://en.cppreference.com/w/cpp/utility/format/formatter#Standard_format_specification)
@@ -10,27 +10,27 @@ For basic usage, any occurrences of `{}` in the format string are replaced with
 form, in order:
 
 ```c++
-DeprecatedString::formatted("Well, {} my {} friends!", "hello", 42) == "Well, hello my 42 friends!";
+ByteString::formatted("Well, {} my {} friends!", "hello", 42) == "Well, hello my 42 friends!";
 ```
 
 If you want to include a literal `{` in the output, use `{{`:
 
 ```c++
-DeprecatedString::formatted("{{ {}", "hello") == "{ hello";
+ByteString::formatted("{{ {}", "hello") == "{ hello";
 ```
 
 You can refer to the arguments by index, if you want to repeat one or change the order:
 
 ```c++
-DeprecatedString::formatted("{2}{0}{1}", "a", "b", "c") == "cab";
+ByteString::formatted("{2}{0}{1}", "a", "b", "c") == "cab";
 ```
 
 To control how the arguments are formatted, add colon after the optional index, and then add format specifier
 characters:
 
 ```c++
-DeprecatedString::formatted("{:.4}", "cool dude") == "cool";
-DeprecatedString::formatted("{0:.4}", "cool dude") == "cool";
+ByteString::formatted("{:.4}", "cool dude") == "cool";
+ByteString::formatted("{0:.4}", "cool dude") == "cool";
 ```
 
 ## Format specifiers
@@ -135,6 +135,6 @@ type cannot be formatted. For example:
 
 ```c++
 // B has a Formatter defined, but A does not.
-DeprecatedString::formatted("{}", FormatIfSupported { A {} }) == "?";
-DeprecatedString::formatted("{}", FormatIfSupported { B {} }) == "B";
+ByteString::formatted("{}", FormatIfSupported { A {} }) == "?";
+ByteString::formatted("{}", FormatIfSupported { B {} }) == "B";
 ```
diff --git a/Ladybird/Android/src/main/cpp/LadybirdActivity.cpp b/Ladybird/Android/src/main/cpp/LadybirdActivity.cpp
index ff2a27ef1d8..8a64051ca1b 100644
--- a/Ladybird/Android/src/main/cpp/LadybirdActivity.cpp
+++ b/Ladybird/Android/src/main/cpp/LadybirdActivity.cpp
@@ -6,7 +6,7 @@
 
 #include "ALooperEventLoopImplementation.h"
 #include "JNIHelpers.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/HashMap.h>
 #include <AK/LexicalPath.h>
@@ -21,7 +21,7 @@
 #include <LibFileSystem/FileSystem.h>
 #include <jni.h>
 
-static ErrorOr<void> extract_tar_archive(String archive_file, DeprecatedString output_directory);
+static ErrorOr<void> extract_tar_archive(String archive_file, ByteString output_directory);
 
 JavaVM* global_vm;
 static OwnPtr<Core::EventLoop> s_main_event_loop;
@@ -89,29 +89,29 @@ Java_org_serenityos_ladybird_LadybirdActivity_disposeNativeCode(JNIEnv* env, job
     delete &Core::EventLoopManager::the();
 }
 
-ErrorOr<void> extract_tar_archive(String archive_file, DeprecatedString output_directory)
+ErrorOr<void> extract_tar_archive(String archive_file, ByteString output_directory)
 {
     constexpr size_t buffer_size = 4096;
 
     auto file = TRY(Core::InputBufferedFile::create(TRY(Core::File::open(archive_file, Core::File::OpenMode::Read))));
 
-    DeprecatedString old_pwd = TRY(Core::System::getcwd());
+    ByteString old_pwd = TRY(Core::System::getcwd());
 
     TRY(Core::System::chdir(output_directory));
     ScopeGuard go_back = [&old_pwd] { MUST(Core::System::chdir(old_pwd)); };
 
     auto tar_stream = TRY(Archive::TarInputStream::construct(move(file)));
 
-    HashMap<DeprecatedString, DeprecatedString> global_overrides;
-    HashMap<DeprecatedString, DeprecatedString> local_overrides;
+    HashMap<ByteString, ByteString> global_overrides;
+    HashMap<ByteString, ByteString> local_overrides;
 
-    auto get_override = [&](StringView key) -> Optional<DeprecatedString> {
-        Optional<DeprecatedString> maybe_local = local_overrides.get(key);
+    auto get_override = [&](StringView key) -> Optional<ByteString> {
+        Optional<ByteString> maybe_local = local_overrides.get(key);
 
         if (maybe_local.has_value())
             return maybe_local;
 
-        Optional<DeprecatedString> maybe_global = global_overrides.get(key);
+        Optional<ByteString> maybe_global = global_overrides.get(key);
 
         if (maybe_global.has_value())
             return maybe_global;
@@ -163,7 +163,7 @@ ErrorOr<void> extract_tar_archive(String archive_file, DeprecatedString output_d
                 long_name.append(reinterpret_cast<char*>(slice.data()), slice.size());
             }
 
-            local_overrides.set("path", long_name.to_deprecated_string());
+            local_overrides.set("path", long_name.to_byte_string());
             TRY(tar_stream->advance());
             continue;
         }
@@ -175,9 +175,9 @@ ErrorOr<void> extract_tar_archive(String archive_file, DeprecatedString output_d
         LexicalPath path = LexicalPath(header.filename());
         if (!header.prefix().is_empty())
             path = path.prepend(header.prefix());
-        DeprecatedString filename = get_override("path"sv).value_or(path.string());
+        ByteString filename = get_override("path"sv).value_or(path.string());
 
-        DeprecatedString absolute_path = TRY(FileSystem::absolute_path(filename)).to_deprecated_string();
+        ByteString absolute_path = TRY(FileSystem::absolute_path(filename)).to_byte_string();
         auto parent_path = LexicalPath(absolute_path).parent();
         auto header_mode = TRY(header.mode());
 
diff --git a/Ladybird/Android/src/main/cpp/WebContentService.cpp b/Ladybird/Android/src/main/cpp/WebContentService.cpp
index f0924bfbbca..a9e6b64b905 100644
--- a/Ladybird/Android/src/main/cpp/WebContentService.cpp
+++ b/Ladybird/Android/src/main/cpp/WebContentService.cpp
@@ -122,9 +122,9 @@ ErrorOr<NonnullRefPtr<Client>> bind_service(void (*bind_method)(int, int))
 
 static ErrorOr<void> load_content_filters()
 {
-    auto file_or_error = Core::File::open(DeprecatedString::formatted("{}/home/anon/.config/BrowserContentFilters.txt", s_serenity_resource_root), Core::File::OpenMode::Read);
+    auto file_or_error = Core::File::open(ByteString::formatted("{}/home/anon/.config/BrowserContentFilters.txt", s_serenity_resource_root), Core::File::OpenMode::Read);
     if (file_or_error.is_error())
-        file_or_error = Core::File::open(DeprecatedString::formatted("{}/res/ladybird/BrowserContentFilters.txt", s_serenity_resource_root), Core::File::OpenMode::Read);
+        file_or_error = Core::File::open(ByteString::formatted("{}/res/ladybird/BrowserContentFilters.txt", s_serenity_resource_root), Core::File::OpenMode::Read);
     if (file_or_error.is_error())
         return file_or_error.release_error();
 
diff --git a/Ladybird/AppKit/Application/ApplicationDelegate.mm b/Ladybird/AppKit/Application/ApplicationDelegate.mm
index 98f3edd2bbc..aeec1252acc 100644
--- a/Ladybird/AppKit/Application/ApplicationDelegate.mm
+++ b/Ladybird/AppKit/Application/ApplicationDelegate.mm
@@ -474,7 +474,7 @@
     [submenu addItem:[NSMenuItem separatorItem]];
 
     auto* spoof_user_agent_menu = [[NSMenu alloc] init];
-    auto add_user_agent = [spoof_user_agent_menu](DeprecatedString name) {
+    auto add_user_agent = [spoof_user_agent_menu](ByteString name) {
         [spoof_user_agent_menu addItem:[[NSMenuItem alloc] initWithTitle:Ladybird::string_to_ns_string(name)
                                                                   action:@selector(setUserAgentSpoof:)
                                                            keyEquivalent:@""]];
diff --git a/Ladybird/AppKit/UI/LadybirdWebView.h b/Ladybird/AppKit/UI/LadybirdWebView.h
index 6ec20458bb5..67150c7d8c0 100644
--- a/Ladybird/AppKit/UI/LadybirdWebView.h
+++ b/Ladybird/AppKit/UI/LadybirdWebView.h
@@ -27,7 +27,7 @@
 - (void)onLoadStart:(URL const&)url isRedirect:(BOOL)is_redirect;
 - (void)onLoadFinish:(URL const&)url;
 
-- (void)onTitleChange:(DeprecatedString const&)title;
+- (void)onTitleChange:(ByteString const&)title;
 - (void)onFaviconChange:(Gfx::Bitmap const&)bitmap;
 
 - (void)onNavigateBack;
@@ -58,7 +58,7 @@
 - (void)resetZoom;
 - (float)zoomLevel;
 
-- (void)debugRequest:(DeprecatedString const&)request argument:(DeprecatedString const&)argument;
+- (void)debugRequest:(ByteString const&)request argument:(ByteString const&)argument;
 
 - (void)viewSource;
 
diff --git a/Ladybird/AppKit/UI/LadybirdWebView.mm b/Ladybird/AppKit/UI/LadybirdWebView.mm
index 646a93f08c3..3ada6c05fbf 100644
--- a/Ladybird/AppKit/UI/LadybirdWebView.mm
+++ b/Ladybird/AppKit/UI/LadybirdWebView.mm
@@ -180,7 +180,7 @@ struct HideCursor {
     m_web_view_bridge->set_preferred_color_scheme(color_scheme);
 }
 
-- (void)debugRequest:(DeprecatedString const&)request argument:(DeprecatedString const&)argument
+- (void)debugRequest:(ByteString const&)request argument:(ByteString const&)argument
 {
     m_web_view_bridge->debug_request(request, argument);
 }
@@ -634,7 +634,7 @@ static void copy_data_to_clipboard(StringView data, NSPasteboardType pasteboard_
         return [delegate cookieJar].get_named_cookie(url, name);
     };
 
-    m_web_view_bridge->on_get_cookie = [](auto const& url, auto source) -> DeprecatedString {
+    m_web_view_bridge->on_get_cookie = [](auto const& url, auto source) -> ByteString {
         auto* delegate = (ApplicationDelegate*)[NSApp delegate];
         return [delegate cookieJar].get_cookie(url, source);
     };
diff --git a/Ladybird/AppKit/UI/Palette.mm b/Ladybird/AppKit/UI/Palette.mm
index 149656d976a..94602b78595 100644
--- a/Ladybird/AppKit/UI/Palette.mm
+++ b/Ladybird/AppKit/UI/Palette.mm
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <Ladybird/Utilities.h>
 #include <LibCore/Resource.h>
 #include <LibGfx/Palette.h>
@@ -33,7 +33,7 @@ Core::AnonymousBuffer create_system_palette()
 
     auto theme_file = is_dark ? "Dark"sv : "Default"sv;
     auto theme_ini = MUST(Core::Resource::load_from_uri(MUST(String::formatted("resource://themes/{}.ini", theme_file))));
-    auto theme = Gfx::load_system_theme(theme_ini->filesystem_path().to_deprecated_string()).release_value_but_fixme_should_propagate_errors();
+    auto theme = Gfx::load_system_theme(theme_ini->filesystem_path().to_byte_string()).release_value_but_fixme_should_propagate_errors();
 
     auto palette_impl = Gfx::PaletteImpl::create_with_anonymous_buffer(theme);
     auto palette = Gfx::Palette(move(palette_impl));
diff --git a/Ladybird/AppKit/UI/Tab.mm b/Ladybird/AppKit/UI/Tab.mm
index ccf8810170b..0d8a2263a45 100644
--- a/Ladybird/AppKit/UI/Tab.mm
+++ b/Ladybird/AppKit/UI/Tab.mm
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/String.h>
 #include <AK/URL.h>
 #include <Ladybird/Utilities.h>
@@ -247,7 +247,7 @@ static constexpr CGFloat const WINDOW_HEIGHT = 800;
     }
 }
 
-- (void)onTitleChange:(DeprecatedString const&)title
+- (void)onTitleChange:(ByteString const&)title
 {
     [[self tabController] onTitleChange:title];
 
diff --git a/Ladybird/AppKit/UI/TabController.h b/Ladybird/AppKit/UI/TabController.h
index 6e47e8264fd..f18fb187913 100644
--- a/Ladybird/AppKit/UI/TabController.h
+++ b/Ladybird/AppKit/UI/TabController.h
@@ -16,7 +16,7 @@ struct TabSettings {
     BOOL scripting_enabled { YES };
     BOOL block_popups { YES };
     BOOL same_origin_policy_enabled { NO };
-    DeprecatedString user_agent_name { "Disabled"sv };
+    ByteString user_agent_name { "Disabled"sv };
 };
 
 @interface TabController : NSWindowController <NSWindowDelegate>
@@ -27,14 +27,14 @@ struct TabSettings {
 - (void)loadHTML:(StringView)html url:(URL const&)url;
 
 - (void)onLoadStart:(URL const&)url isRedirect:(BOOL)isRedirect;
-- (void)onTitleChange:(DeprecatedString const&)title;
+- (void)onTitleChange:(ByteString const&)title;
 
 - (void)navigateBack:(id)sender;
 - (void)navigateForward:(id)sender;
 - (void)reload:(id)sender;
 - (void)clearHistory;
 
-- (void)debugRequest:(DeprecatedString const&)request argument:(DeprecatedString const&)argument;
+- (void)debugRequest:(ByteString const&)request argument:(ByteString const&)argument;
 
 - (void)focusLocationToolbarItem;
 
diff --git a/Ladybird/AppKit/UI/TabController.mm b/Ladybird/AppKit/UI/TabController.mm
index 286dfa5c0fc..ba8afb9e738 100644
--- a/Ladybird/AppKit/UI/TabController.mm
+++ b/Ladybird/AppKit/UI/TabController.mm
@@ -54,7 +54,7 @@ enum class IsHistoryNavigation {
 
 @interface TabController () <NSToolbarDelegate, NSSearchFieldDelegate>
 {
-    DeprecatedString m_title;
+    ByteString m_title;
 
     WebView::History m_history;
     IsHistoryNavigation m_is_history_navigation;
@@ -133,7 +133,7 @@ enum class IsHistoryNavigation {
     [self updateNavigationButtonStates];
 }
 
-- (void)onTitleChange:(DeprecatedString const&)title
+- (void)onTitleChange:(ByteString const&)title
 {
     m_title = title;
     m_history.update_title(m_title);
@@ -201,7 +201,7 @@ enum class IsHistoryNavigation {
     [self updateNavigationButtonStates];
 }
 
-- (void)debugRequest:(DeprecatedString const&)request argument:(DeprecatedString const&)argument
+- (void)debugRequest:(ByteString const&)request argument:(ByteString const&)argument
 {
     if (request == "dump-history") {
         m_history.dump();
@@ -390,8 +390,8 @@ enum class IsHistoryNavigation {
 
 - (void)setUserAgentSpoof:(NSMenuItem*)sender
 {
-    DeprecatedString const user_agent_name = [[sender title] UTF8String];
-    DeprecatedString user_agent = "";
+    ByteString const user_agent_name = [[sender title] UTF8String];
+    ByteString user_agent = "";
     if (user_agent_name == "Disabled"sv) {
         user_agent = Web::default_user_agent;
     } else {
diff --git a/Ladybird/FontPlugin.cpp b/Ladybird/FontPlugin.cpp
index 2e8dac841b4..fda4fa06715 100644
--- a/Ladybird/FontPlugin.cpp
+++ b/Ladybird/FontPlugin.cpp
@@ -6,13 +6,13 @@
  */
 
 #include "FontPlugin.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/String.h>
 #include <LibCore/StandardPaths.h>
 #include <LibGfx/Font/Emoji.h>
 #include <LibGfx/Font/FontDatabase.h>
 
-extern DeprecatedString s_serenity_resource_root;
+extern ByteString s_serenity_resource_root;
 
 namespace Ladybird {
 
diff --git a/Ladybird/Qt/AutoComplete.cpp b/Ladybird/Qt/AutoComplete.cpp
index 4afd9299b04..d743f93dd33 100644
--- a/Ladybird/Qt/AutoComplete.cpp
+++ b/Ladybird/Qt/AutoComplete.cpp
@@ -45,7 +45,7 @@ ErrorOr<void> AutoComplete::parse_google_autocomplete(Vector<JsonValue> const& j
 
     if (!json[0].is_string())
         return Error::from_string_view("Invalid JSON, expected first element to be a string"sv);
-    auto query = TRY(String::from_deprecated_string(json[0].as_string()));
+    auto query = TRY(String::from_byte_string(json[0].as_string()));
 
     if (!json[1].is_array())
         return Error::from_string_view("Invalid JSON, expected second element to be an array"sv);
@@ -55,7 +55,7 @@ ErrorOr<void> AutoComplete::parse_google_autocomplete(Vector<JsonValue> const& j
         return Error::from_string_view("Invalid JSON, query does not match"sv);
 
     for (auto& suggestion : suggestions_array) {
-        m_auto_complete_model->add(TRY(String::from_deprecated_string(suggestion.as_string())));
+        m_auto_complete_model->add(TRY(String::from_byte_string(suggestion.as_string())));
     }
 
     return {};
@@ -67,7 +67,7 @@ ErrorOr<void> AutoComplete::parse_duckduckgo_autocomplete(Vector<JsonValue> cons
         auto maybe_value = suggestion.as_object().get("phrase"sv);
         if (!maybe_value.has_value())
             continue;
-        m_auto_complete_model->add(TRY(String::from_deprecated_string(maybe_value->as_string())));
+        m_auto_complete_model->add(TRY(String::from_byte_string(maybe_value->as_string())));
     }
 
     return {};
@@ -77,7 +77,7 @@ ErrorOr<void> AutoComplete::parse_yahoo_autocomplete(JsonObject const& json)
 {
     if (!json.get("q"sv).has_value() || !json.get("q"sv)->is_string())
         return Error::from_string_view("Invalid JSON, expected \"q\" to be a string"sv);
-    auto query = TRY(String::from_deprecated_string(json.get("q"sv)->as_string()));
+    auto query = TRY(String::from_byte_string(json.get("q"sv)->as_string()));
 
     if (!json.get("r"sv).has_value() || !json.get("r"sv)->is_array())
         return Error::from_string_view("Invalid JSON, expected \"r\" to be an object"sv);
@@ -94,7 +94,7 @@ ErrorOr<void> AutoComplete::parse_yahoo_autocomplete(JsonObject const& json)
         if (!suggestion.get("k"sv).has_value() || !suggestion.get("k"sv)->is_string())
             return Error::from_string_view("Invalid JSON, expected \"k\" to be a string"sv);
 
-        m_auto_complete_model->add(TRY(String::from_deprecated_string(suggestion.get("k"sv)->as_string())));
+        m_auto_complete_model->add(TRY(String::from_byte_string(suggestion.get("k"sv)->as_string())));
     };
 
     return {};
@@ -105,7 +105,7 @@ ErrorOr<void> AutoComplete::got_network_response(QNetworkReply* reply)
     if (reply->error() == QNetworkReply::NetworkError::OperationCanceledError)
         return {};
 
-    AK::JsonParser parser(ak_deprecated_string_from_qstring(reply->readAll()));
+    AK::JsonParser parser(ak_byte_string_from_qstring(reply->readAll()));
     auto json = TRY(parser.parse());
 
     auto engine_name = Settings::the()->autocomplete_engine().name;
diff --git a/Ladybird/Qt/BrowserWindow.cpp b/Ladybird/Qt/BrowserWindow.cpp
index da39f64d508..804d380db71 100644
--- a/Ladybird/Qt/BrowserWindow.cpp
+++ b/Ladybird/Qt/BrowserWindow.cpp
@@ -331,7 +331,7 @@ BrowserWindow::BrowserWindow(Vector<URL> const& initial_urls, WebView::CookieJar
     auto* disable_spoofing = add_user_agent("Disabled"sv, Web::default_user_agent);
     disable_spoofing->setChecked(true);
     for (auto const& user_agent : WebView::user_agents)
-        add_user_agent(user_agent.key, user_agent.value.to_deprecated_string());
+        add_user_agent(user_agent.key, user_agent.value.to_byte_string());
 
     auto* custom_user_agent_action = new QAction("Custom...", this);
     custom_user_agent_action->setCheckable(true);
@@ -340,7 +340,7 @@ BrowserWindow::BrowserWindow(Vector<URL> const& initial_urls, WebView::CookieJar
     QObject::connect(custom_user_agent_action, &QAction::triggered, this, [this, disable_spoofing] {
         auto user_agent = QInputDialog::getText(this, "Custom User Agent", "Enter User Agent:");
         if (!user_agent.isEmpty()) {
-            debug_request("spoof-user-agent", ak_deprecated_string_from_qstring(user_agent));
+            debug_request("spoof-user-agent", ak_byte_string_from_qstring(user_agent));
             debug_request("clear-cache"); // clear the cache to ensure requests are re-done with the new user agent
         } else {
             disable_spoofing->activate(QAction::Trigger);
@@ -455,7 +455,7 @@ void BrowserWindow::set_current_tab(Tab* tab)
         update_displayed_zoom_level();
 }
 
-void BrowserWindow::debug_request(DeprecatedString const& request, DeprecatedString const& argument)
+void BrowserWindow::debug_request(ByteString const& request, ByteString const& argument)
 {
     if (!m_current_tab)
         return;
@@ -505,7 +505,7 @@ Tab& BrowserWindow::create_new_tab(Web::HTML::ActivateTab activate_tab)
     };
 
     tab->view().on_tab_open_request = [this](auto url, auto activate_tab) {
-        auto& tab = new_tab(qstring_from_ak_string(url.to_deprecated_string()), activate_tab);
+        auto& tab = new_tab(qstring_from_ak_string(url.to_byte_string()), activate_tab);
         return tab.view().handle();
     };
 
@@ -533,7 +533,7 @@ Tab& BrowserWindow::create_new_tab(Web::HTML::ActivateTab activate_tab)
         return m_cookie_jar.get_named_cookie(url, name);
     };
 
-    tab->view().on_get_cookie = [this](auto& url, auto source) -> DeprecatedString {
+    tab->view().on_get_cookie = [this](auto& url, auto source) -> ByteString {
         return m_cookie_jar.get_cookie(url, source);
     };
 
diff --git a/Ladybird/Qt/BrowserWindow.h b/Ladybird/Qt/BrowserWindow.h
index 3cf612a7279..0315e9f57e3 100644
--- a/Ladybird/Qt/BrowserWindow.h
+++ b/Ladybird/Qt/BrowserWindow.h
@@ -102,7 +102,7 @@ private:
 
     Tab& create_new_tab(Web::HTML::ActivateTab activate_tab);
 
-    void debug_request(DeprecatedString const& request, DeprecatedString const& argument = "");
+    void debug_request(ByteString const& request, ByteString const& argument = "");
 
     void set_current_tab(Tab* tab);
     void update_displayed_zoom_level();
diff --git a/Ladybird/Qt/RequestManagerQt.cpp b/Ladybird/Qt/RequestManagerQt.cpp
index e05fc95f8c9..7ff68da45a5 100644
--- a/Ladybird/Qt/RequestManagerQt.cpp
+++ b/Ladybird/Qt/RequestManagerQt.cpp
@@ -24,7 +24,7 @@ void RequestManagerQt::reply_finished(QNetworkReply* reply)
     request->did_finish();
 }
 
-RefPtr<Web::ResourceLoaderConnectorRequest> RequestManagerQt::start_request(DeprecatedString const& method, AK::URL const& url, HashMap<DeprecatedString, DeprecatedString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const& proxy)
+RefPtr<Web::ResourceLoaderConnectorRequest> RequestManagerQt::start_request(ByteString const& method, AK::URL const& url, HashMap<ByteString, ByteString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const& proxy)
 {
     if (!url.scheme().bytes_as_string_view().is_one_of_ignoring_ascii_case("http"sv, "https"sv)) {
         return nullptr;
@@ -38,9 +38,9 @@ RefPtr<Web::ResourceLoaderConnectorRequest> RequestManagerQt::start_request(Depr
     return request;
 }
 
-ErrorOr<NonnullRefPtr<RequestManagerQt::Request>> RequestManagerQt::Request::create(QNetworkAccessManager& qnam, DeprecatedString const& method, AK::URL const& url, HashMap<DeprecatedString, DeprecatedString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&)
+ErrorOr<NonnullRefPtr<RequestManagerQt::Request>> RequestManagerQt::Request::create(QNetworkAccessManager& qnam, ByteString const& method, AK::URL const& url, HashMap<ByteString, ByteString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&)
 {
-    QNetworkRequest request { QString(url.to_deprecated_string().characters()) };
+    QNetworkRequest request { QString(url.to_byte_string().characters()) };
     request.setAttribute(QNetworkRequest::RedirectPolicyAttribute, QNetworkRequest::ManualRedirectPolicy);
     request.setAttribute(QNetworkRequest::CookieLoadControlAttribute, QNetworkRequest::Manual);
     request.setAttribute(QNetworkRequest::CookieSaveControlAttribute, QNetworkRequest::Manual);
@@ -87,11 +87,11 @@ void RequestManagerQt::Request::did_finish()
 {
     auto buffer = m_reply.readAll();
     auto http_status_code = m_reply.attribute(QNetworkRequest::Attribute::HttpStatusCodeAttribute).toInt();
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> response_headers;
-    Vector<DeprecatedString> set_cookie_headers;
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> response_headers;
+    Vector<ByteString> set_cookie_headers;
     for (auto& it : m_reply.rawHeaderPairs()) {
-        auto name = DeprecatedString(it.first.data(), it.first.length());
-        auto value = DeprecatedString(it.second.data(), it.second.length());
+        auto name = ByteString(it.first.data(), it.first.length());
+        auto value = ByteString(it.second.data(), it.second.length());
         if (name.equals_ignoring_ascii_case("set-cookie"sv)) {
             // NOTE: Qt may have bundled multiple Set-Cookie headers into a single one.
             //       We have to extract the full list of cookies via QNetworkReply::header().
@@ -104,7 +104,7 @@ void RequestManagerQt::Request::did_finish()
         }
     }
     if (!set_cookie_headers.is_empty()) {
-        response_headers.set("set-cookie"sv, JsonArray { set_cookie_headers }.to_deprecated_string());
+        response_headers.set("set-cookie"sv, JsonArray { set_cookie_headers }.to_byte_string());
     }
     bool success = http_status_code != 0;
     on_buffered_request_finish(success, buffer.length(), response_headers, http_status_code, ReadonlyBytes { buffer.data(), (size_t)buffer.size() });
diff --git a/Ladybird/Qt/RequestManagerQt.h b/Ladybird/Qt/RequestManagerQt.h
index 9728db76e31..3b6a8faa97d 100644
--- a/Ladybird/Qt/RequestManagerQt.h
+++ b/Ladybird/Qt/RequestManagerQt.h
@@ -27,7 +27,7 @@ public:
     virtual void prefetch_dns(AK::URL const&) override { }
     virtual void preconnect(AK::URL const&) override { }
 
-    virtual RefPtr<Web::ResourceLoaderConnectorRequest> start_request(DeprecatedString const& method, AK::URL const&, HashMap<DeprecatedString, DeprecatedString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&) override;
+    virtual RefPtr<Web::ResourceLoaderConnectorRequest> start_request(ByteString const& method, AK::URL const&, HashMap<ByteString, ByteString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&) override;
 
 private slots:
     void reply_finished(QNetworkReply*);
@@ -38,7 +38,7 @@ private:
     class Request
         : public Web::ResourceLoaderConnectorRequest {
     public:
-        static ErrorOr<NonnullRefPtr<Request>> create(QNetworkAccessManager& qnam, DeprecatedString const& method, AK::URL const& url, HashMap<DeprecatedString, DeprecatedString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&);
+        static ErrorOr<NonnullRefPtr<Request>> create(QNetworkAccessManager& qnam, ByteString const& method, AK::URL const& url, HashMap<ByteString, ByteString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&);
 
         virtual ~Request() override;
 
diff --git a/Ladybird/Qt/Settings.h b/Ladybird/Qt/Settings.h
index 076d4f14525..e061f8d0a30 100644
--- a/Ladybird/Qt/Settings.h
+++ b/Ladybird/Qt/Settings.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/OwnPtr.h>
 #include <LibWebView/SearchEngine.h>
 #include <QPoint>
diff --git a/Ladybird/Qt/StringUtils.cpp b/Ladybird/Qt/StringUtils.cpp
index 56f9725d4a5..ce26c6b7b7e 100644
--- a/Ladybird/Qt/StringUtils.cpp
+++ b/Ladybird/Qt/StringUtils.cpp
@@ -6,9 +6,9 @@
 
 #include "StringUtils.h"
 
-AK::DeprecatedString ak_deprecated_string_from_qstring(QString const& qstring)
+AK::ByteString ak_byte_string_from_qstring(QString const& qstring)
 {
-    return AK::DeprecatedString(qstring.toUtf8().data());
+    return AK::ByteString(qstring.toUtf8().data());
 }
 
 String ak_string_from_qstring(QString const& qstring)
diff --git a/Ladybird/Qt/StringUtils.h b/Ladybird/Qt/StringUtils.h
index d04b1298c08..7c856f7b7d9 100644
--- a/Ladybird/Qt/StringUtils.h
+++ b/Ladybird/Qt/StringUtils.h
@@ -6,12 +6,12 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/String.h>
 #include <AK/StringView.h>
 #include <QString>
 
-AK::DeprecatedString ak_deprecated_string_from_qstring(QString const&);
+AK::ByteString ak_byte_string_from_qstring(QString const&);
 String ak_string_from_qstring(QString const&);
 QString qstring_from_ak_string(StringView);
diff --git a/Ladybird/Qt/Tab.cpp b/Ladybird/Qt/Tab.cpp
index 29c99faa2d3..5466ba9ad03 100644
--- a/Ladybird/Qt/Tab.cpp
+++ b/Ladybird/Qt/Tab.cpp
@@ -107,7 +107,7 @@ Tab::Tab(BrowserWindow* window, WebContentOptions const& web_content_options, St
     };
 
     view().on_link_hover = [this](auto const& url) {
-        m_hover_label->setText(qstring_from_ak_string(url.to_deprecated_string()));
+        m_hover_label->setText(qstring_from_ak_string(url.to_byte_string()));
         update_hover_label();
         m_hover_label->show();
     };
@@ -123,7 +123,7 @@ Tab::Tab(BrowserWindow* window, WebContentOptions const& web_content_options, St
             m_history.replace_current(url, m_title.toUtf8().data());
         }
 
-        m_location_edit->setText(url.to_deprecated_string().characters());
+        m_location_edit->setText(url.to_byte_string().characters());
         m_location_edit->setCursorPosition(0);
 
         // Don't add to history if back or forward is pressed
@@ -648,7 +648,7 @@ void Tab::back()
 
     m_is_history_navigation = true;
     m_history.go_back();
-    view().load(m_history.current().url.to_deprecated_string());
+    view().load(m_history.current().url.to_byte_string());
 }
 
 void Tab::forward()
@@ -658,7 +658,7 @@ void Tab::forward()
 
     m_is_history_navigation = true;
     m_history.go_forward();
-    view().load(m_history.current().url.to_deprecated_string());
+    view().load(m_history.current().url.to_byte_string());
 }
 
 void Tab::reload()
@@ -667,7 +667,7 @@ void Tab::reload()
         return;
 
     m_is_history_navigation = true;
-    view().load(m_history.current().url.to_deprecated_string());
+    view().load(m_history.current().url.to_byte_string());
 }
 
 void Tab::open_link(URL const& url)
@@ -703,7 +703,7 @@ int Tab::tab_index()
     return m_window->tab_index(this);
 }
 
-void Tab::debug_request(DeprecatedString const& request, DeprecatedString const& argument)
+void Tab::debug_request(ByteString const& request, ByteString const& argument)
 {
     if (request == "dump-history")
         m_history.dump();
diff --git a/Ladybird/Qt/Tab.h b/Ladybird/Qt/Tab.h
index 50bbf11f27b..71d5b89aca8 100644
--- a/Ladybird/Qt/Tab.h
+++ b/Ladybird/Qt/Tab.h
@@ -40,7 +40,7 @@ public:
     void forward();
     void reload();
 
-    void debug_request(DeprecatedString const& request, DeprecatedString const& argument);
+    void debug_request(ByteString const& request, ByteString const& argument);
 
     void open_file();
     void update_reset_zoom_button();
diff --git a/Ladybird/Qt/WebContentView.cpp b/Ladybird/Qt/WebContentView.cpp
index 61b465632a9..46c0e6d9ee9 100644
--- a/Ladybird/Qt/WebContentView.cpp
+++ b/Ladybird/Qt/WebContentView.cpp
@@ -576,7 +576,7 @@ static Core::AnonymousBuffer make_system_theme_from_qt_palette(QWidget& widget,
 
     auto theme_file = mode == WebContentView::PaletteMode::Default ? "Default"sv : "Dark"sv;
     auto theme_ini = MUST(Core::Resource::load_from_uri(MUST(String::formatted("resource://themes/{}.ini", theme_file))));
-    auto theme = Gfx::load_system_theme(theme_ini->filesystem_path().to_deprecated_string()).release_value_but_fixme_should_propagate_errors();
+    auto theme = Gfx::load_system_theme(theme_ini->filesystem_path().to_byte_string()).release_value_but_fixme_should_propagate_errors();
 
     auto palette_impl = Gfx::PaletteImpl::create_with_anonymous_buffer(theme);
     auto palette = Gfx::Palette(move(palette_impl));
@@ -752,7 +752,7 @@ bool WebContentView::event(QEvent* event)
 
 ErrorOr<String> WebContentView::dump_layout_tree()
 {
-    return String::from_deprecated_string(client().dump_layout_tree());
+    return String::from_byte_string(client().dump_layout_tree());
 }
 
 }
diff --git a/Ladybird/Qt/WebContentView.h b/Ladybird/Qt/WebContentView.h
index f72155f7747..d3af87da715 100644
--- a/Ladybird/Qt/WebContentView.h
+++ b/Ladybird/Qt/WebContentView.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
diff --git a/Ladybird/Qt/WebSocketClientManagerQt.cpp b/Ladybird/Qt/WebSocketClientManagerQt.cpp
index da02babcfc2..e8087579ab9 100644
--- a/Ladybird/Qt/WebSocketClientManagerQt.cpp
+++ b/Ladybird/Qt/WebSocketClientManagerQt.cpp
@@ -19,7 +19,7 @@ NonnullRefPtr<WebSocketClientManagerQt> WebSocketClientManagerQt::create()
 WebSocketClientManagerQt::WebSocketClientManagerQt() = default;
 WebSocketClientManagerQt::~WebSocketClientManagerQt() = default;
 
-RefPtr<Web::WebSockets::WebSocketClientSocket> WebSocketClientManagerQt::connect(AK::URL const& url, DeprecatedString const& origin, Vector<DeprecatedString> const& protocols)
+RefPtr<Web::WebSockets::WebSocketClientSocket> WebSocketClientManagerQt::connect(AK::URL const& url, ByteString const& origin, Vector<ByteString> const& protocols)
 {
     WebSocket::ConnectionInfo connection_info(url);
     connection_info.set_origin(origin);
diff --git a/Ladybird/Qt/WebSocketClientManagerQt.h b/Ladybird/Qt/WebSocketClientManagerQt.h
index 54014036be1..85930ef7cd9 100644
--- a/Ladybird/Qt/WebSocketClientManagerQt.h
+++ b/Ladybird/Qt/WebSocketClientManagerQt.h
@@ -19,7 +19,7 @@ public:
     static NonnullRefPtr<WebSocketClientManagerQt> create();
 
     virtual ~WebSocketClientManagerQt() override;
-    virtual RefPtr<Web::WebSockets::WebSocketClientSocket> connect(AK::URL const&, DeprecatedString const& origin, Vector<DeprecatedString> const& protocols) override;
+    virtual RefPtr<Web::WebSockets::WebSocketClientSocket> connect(AK::URL const&, ByteString const& origin, Vector<ByteString> const& protocols) override;
 
 private:
     WebSocketClientManagerQt();
diff --git a/Ladybird/Qt/WebSocketImplQt.cpp b/Ladybird/Qt/WebSocketImplQt.cpp
index e73ea7473c3..ff6a01e0e9d 100644
--- a/Ladybird/Qt/WebSocketImplQt.cpp
+++ b/Ladybird/Qt/WebSocketImplQt.cpp
@@ -85,13 +85,13 @@ ErrorOr<ByteBuffer> WebSocketImplQt::read(int max_size)
     return buffer.slice(0, bytes_read);
 }
 
-ErrorOr<DeprecatedString> WebSocketImplQt::read_line(size_t size)
+ErrorOr<ByteString> WebSocketImplQt::read_line(size_t size)
 {
     auto buffer = TRY(ByteBuffer::create_uninitialized(size));
     auto bytes_read = m_socket->readLine(reinterpret_cast<char*>(buffer.data()), buffer.size());
     if (bytes_read == -1)
         return Error::from_string_literal("WebSocketImplQt::read_line(): Error reading from socket");
-    return DeprecatedString::copy(buffer.span().slice(0, bytes_read));
+    return ByteString::copy(buffer.span().slice(0, bytes_read));
 }
 
 }
diff --git a/Ladybird/Qt/WebSocketImplQt.h b/Ladybird/Qt/WebSocketImplQt.h
index 6285d53f46c..e9810d52db6 100644
--- a/Ladybird/Qt/WebSocketImplQt.h
+++ b/Ladybird/Qt/WebSocketImplQt.h
@@ -22,7 +22,7 @@ public:
 
     virtual void connect(WebSocket::ConnectionInfo const&) override;
     virtual bool can_read_line() override;
-    virtual ErrorOr<DeprecatedString> read_line(size_t) override;
+    virtual ErrorOr<ByteString> read_line(size_t) override;
     virtual ErrorOr<ByteBuffer> read(int max_size) override;
     virtual bool send(ReadonlyBytes) override;
     virtual bool eof() override;
diff --git a/Ladybird/Qt/WebSocketQt.cpp b/Ladybird/Qt/WebSocketQt.cpp
index 751a52ae7ea..86b4043ea9d 100644
--- a/Ladybird/Qt/WebSocketQt.cpp
+++ b/Ladybird/Qt/WebSocketQt.cpp
@@ -50,7 +50,7 @@ WebSocketQt::WebSocketQt(NonnullRefPtr<WebSocket::WebSocket> underlying_socket)
             }
         }
     };
-    m_websocket->on_close = [weak_this = make_weak_ptr()](u16 code, DeprecatedString reason, bool was_clean) {
+    m_websocket->on_close = [weak_this = make_weak_ptr()](u16 code, ByteString reason, bool was_clean) {
         if (auto strong_this = weak_this.strong_ref())
             if (strong_this->on_close)
                 strong_this->on_close(code, move(reason), was_clean);
@@ -74,7 +74,7 @@ Web::WebSockets::WebSocket::ReadyState WebSocketQt::ready_state()
     VERIFY_NOT_REACHED();
 }
 
-DeprecatedString WebSocketQt::subprotocol_in_use()
+ByteString WebSocketQt::subprotocol_in_use()
 {
     return m_websocket->subprotocol_in_use();
 }
@@ -89,7 +89,7 @@ void WebSocketQt::send(StringView message)
     m_websocket->send(WebSocket::Message(message));
 }
 
-void WebSocketQt::close(u16 code, DeprecatedString reason)
+void WebSocketQt::close(u16 code, ByteString reason)
 {
     m_websocket->close(code, reason);
 }
diff --git a/Ladybird/Qt/WebSocketQt.h b/Ladybird/Qt/WebSocketQt.h
index 34cff6c070a..be792e9aded 100644
--- a/Ladybird/Qt/WebSocketQt.h
+++ b/Ladybird/Qt/WebSocketQt.h
@@ -21,10 +21,10 @@ public:
     virtual ~WebSocketQt() override;
 
     virtual Web::WebSockets::WebSocket::ReadyState ready_state() override;
-    virtual DeprecatedString subprotocol_in_use() override;
+    virtual ByteString subprotocol_in_use() override;
     virtual void send(ByteBuffer binary_or_text_message, bool is_text) override;
     virtual void send(StringView message) override;
-    virtual void close(u16 code, DeprecatedString reason) override;
+    virtual void close(u16 code, ByteString reason) override;
 
 private:
     explicit WebSocketQt(NonnullRefPtr<WebSocket::WebSocket>);
diff --git a/Ladybird/SQLServer/main.cpp b/Ladybird/SQLServer/main.cpp
index 5bed2cba5be..6c04eb38933 100644
--- a/Ladybird/SQLServer/main.cpp
+++ b/Ladybird/SQLServer/main.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/Directory.h>
 #include <LibCore/EventLoop.h>
@@ -17,7 +17,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     AK::set_rich_debug_enabled(true);
 
-    DeprecatedString pid_file;
+    ByteString pid_file;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(pid_file, "Path to the PID file for the SQLServer singleton process", "pid-file", 'p', "pid_file");
@@ -25,7 +25,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     VERIFY(!pid_file.is_empty());
 
-    auto database_path = DeprecatedString::formatted("{}/Ladybird", Core::StandardPaths::data_directory());
+    auto database_path = ByteString::formatted("{}/Ladybird", Core::StandardPaths::data_directory());
     TRY(Core::Directory::create(database_path, Core::Directory::CreateDirectories::Yes));
 
     Core::EventLoop loop;
diff --git a/Ladybird/Utilities.cpp b/Ladybird/Utilities.cpp
index 5897abe7a34..0e2e0be0766 100644
--- a/Ladybird/Utilities.cpp
+++ b/Ladybird/Utilities.cpp
@@ -12,13 +12,13 @@
 #include <LibCore/System.h>
 #include <LibFileSystem/FileSystem.h>
 
-DeprecatedString s_serenity_resource_root;
+ByteString s_serenity_resource_root;
 
 ErrorOr<String> application_directory()
 {
     auto current_executable_path = TRY(Core::System::current_executable_path());
     auto dirname = LexicalPath::dirname(current_executable_path);
-    return String::from_deprecated_string(dirname);
+    return String::from_byte_string(dirname);
 }
 
 void platform_init()
@@ -26,14 +26,14 @@ void platform_init()
     s_serenity_resource_root = [] {
         auto const* source_dir = getenv("SERENITY_SOURCE_DIR");
         if (source_dir) {
-            return DeprecatedString::formatted("{}/Base", source_dir);
+            return ByteString::formatted("{}/Base", source_dir);
         }
         auto* home = getenv("XDG_CONFIG_HOME") ?: getenv("HOME");
         VERIFY(home);
-        auto home_lagom = DeprecatedString::formatted("{}/.lagom", home);
+        auto home_lagom = ByteString::formatted("{}/.lagom", home);
         if (FileSystem::is_directory(home_lagom))
             return home_lagom;
-        auto app_dir = application_directory().release_value_but_fixme_should_propagate_errors().to_deprecated_string();
+        auto app_dir = application_directory().release_value_but_fixme_should_propagate_errors().to_byte_string();
 #ifdef AK_OS_MACOS
         return LexicalPath(app_dir).parent().append("Resources"sv).string();
 #else
diff --git a/Ladybird/Utilities.h b/Ladybird/Utilities.h
index 8194d2339a7..f754fbee5a0 100644
--- a/Ladybird/Utilities.h
+++ b/Ladybird/Utilities.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/String.h>
 #include <AK/Vector.h>
@@ -16,4 +16,4 @@ void platform_init();
 ErrorOr<String> application_directory();
 ErrorOr<Vector<String>> get_paths_for_helper_process(StringView process_name);
 
-extern DeprecatedString s_serenity_resource_root;
+extern ByteString s_serenity_resource_root;
diff --git a/Ladybird/WebContent/main.cpp b/Ladybird/WebContent/main.cpp
index 50c05fbfb48..c10e12baf44 100644
--- a/Ladybird/WebContent/main.cpp
+++ b/Ladybird/WebContent/main.cpp
@@ -131,9 +131,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
 static ErrorOr<void> load_content_filters()
 {
-    auto file_or_error = Core::File::open(DeprecatedString::formatted("{}/home/anon/.config/BrowserContentFilters.txt", s_serenity_resource_root), Core::File::OpenMode::Read);
+    auto file_or_error = Core::File::open(ByteString::formatted("{}/home/anon/.config/BrowserContentFilters.txt", s_serenity_resource_root), Core::File::OpenMode::Read);
     if (file_or_error.is_error())
-        file_or_error = Core::File::open(DeprecatedString::formatted("{}/res/ladybird/BrowserContentFilters.txt", s_serenity_resource_root), Core::File::OpenMode::Read);
+        file_or_error = Core::File::open(ByteString::formatted("{}/res/ladybird/BrowserContentFilters.txt", s_serenity_resource_root), Core::File::OpenMode::Read);
     if (file_or_error.is_error())
         return file_or_error.release_error();
 
diff --git a/Ladybird/WebDriver/main.cpp b/Ladybird/WebDriver/main.cpp
index b688d8db7b6..ba29a44a540 100644
--- a/Ladybird/WebDriver/main.cpp
+++ b/Ladybird/WebDriver/main.cpp
@@ -30,7 +30,7 @@ static ErrorOr<pid_t> launch_process(StringView application, ReadonlySpan<char c
     return result;
 }
 
-static ErrorOr<pid_t> launch_browser(DeprecatedString const& socket_path)
+static ErrorOr<pid_t> launch_browser(ByteString const& socket_path)
 {
     return launch_process("Ladybird"sv,
         Array {
@@ -40,9 +40,9 @@ static ErrorOr<pid_t> launch_browser(DeprecatedString const& socket_path)
         });
 }
 
-static ErrorOr<pid_t> launch_headless_browser(DeprecatedString const& socket_path)
+static ErrorOr<pid_t> launch_headless_browser(ByteString const& socket_path)
 {
-    auto resources = DeprecatedString::formatted("{}/res", s_serenity_resource_root);
+    auto resources = ByteString::formatted("{}/res", s_serenity_resource_root);
     return launch_process("headless-browser"sv,
         Array {
             "--resources",
@@ -78,7 +78,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     platform_init();
 
-    auto webdriver_socket_path = DeprecatedString::formatted("{}/webdriver", TRY(Core::StandardPaths::runtime_directory()));
+    auto webdriver_socket_path = ByteString::formatted("{}/webdriver", TRY(Core::StandardPaths::runtime_directory()));
     TRY(Core::Directory::create(webdriver_socket_path, Core::Directory::CreateDirectories::Yes));
 
     Core::EventLoop loop;
diff --git a/Meta/Lagom/Contrib/MacPDF/AppDelegate.mm b/Meta/Lagom/Contrib/MacPDF/AppDelegate.mm
index c0af16b6fd1..5e65b5fdd02 100644
--- a/Meta/Lagom/Contrib/MacPDF/AppDelegate.mm
+++ b/Meta/Lagom/Contrib/MacPDF/AppDelegate.mm
@@ -22,7 +22,7 @@
     NSString* source_root = [[NSBundle mainBundle] executablePath];
     for (int i = 0; i < 7; ++i)
         source_root = [source_root stringByDeletingLastPathComponent];
-    auto source_root_string = DeprecatedString([source_root UTF8String]);
+    auto source_root_string = ByteString([source_root UTF8String]);
     Core::ResourceImplementation::install(make<Core::ResourceImplementationFile>(MUST(String::formatted("{}/Base/res", source_root_string))));
 }
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/GMLCompiler/main.cpp b/Meta/Lagom/Tools/CodeGenerators/GMLCompiler/main.cpp
index 02812376f35..bc6a6b66d0b 100644
--- a/Meta/Lagom/Tools/CodeGenerators/GMLCompiler/main.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/GMLCompiler/main.cpp
@@ -68,16 +68,16 @@ static bool is_ui_dimension_property(StringView property)
 }
 
 // FIXME: Since normal string-based properties take either String or StringView (and the latter can be implicitly constructed from the former),
-//        we need to special-case DeprecatedString property setters while those still exist.
+//        we need to special-case ByteString property setters while those still exist.
 //        Please remove a setter from this list once it uses StringView or String.
-static bool takes_deprecated_string(StringView property)
+static bool takes_byte_string(StringView property)
 {
-    static HashTable<StringView> deprecated_string_properties;
-    if (deprecated_string_properties.is_empty()) {
-        deprecated_string_properties.set("icon_from_path"sv);
-        deprecated_string_properties.set("name"sv);
+    static HashTable<StringView> byte_string_properties;
+    if (byte_string_properties.is_empty()) {
+        byte_string_properties.set("icon_from_path"sv);
+        byte_string_properties.set("name"sv);
     }
-    return deprecated_string_properties.contains(property);
+    return byte_string_properties.contains(property);
 }
 
 static ErrorOr<String> include_path_for(StringView class_name, LexicalPath const& gml_file_name)
@@ -141,7 +141,7 @@ static char const footer[] = R"~~~(
 
 static ErrorOr<String> escape_string(JsonValue to_escape)
 {
-    auto string = TRY(String::from_deprecated_string(to_escape.as_string()));
+    auto string = TRY(String::from_byte_string(to_escape.as_string()));
 
     // All C++ simple escape sequences; see https://en.cppreference.com/w/cpp/language/escape
     // Other commonly-escaped characters are hard-to-type Unicode and therefore fine to include verbatim in UTF-8 coded strings.
@@ -194,7 +194,7 @@ static ErrorOr<String> generate_initializer_for(Optional<StringView> property_na
 {
     if (value.is_string()) {
         if (property_name.has_value()) {
-            if (takes_deprecated_string(*property_name))
+            if (takes_byte_string(*property_name))
                 return String::formatted(R"~~~("{}"sv)~~~", TRY(escape_string(value)));
 
             if (auto const enum_value = TRY(generate_enum_initializer_for(*property_name, value)); enum_value.has_value())
@@ -252,7 +252,7 @@ static ErrorOr<String> generate_initializer_for(Optional<StringView> property_na
 // All loading happens in a separate block.
 static ErrorOr<void> generate_loader_for_object(GUI::GML::Object const& gml_object, SourceGenerator generator, String object_name, size_t indentation, UseObjectConstructor use_object_constructor)
 {
-    generator.set("object_name", object_name.to_deprecated_string());
+    generator.set("object_name", object_name.to_byte_string());
     generator.set("class_name", gml_object.name());
 
     auto append = [&]<size_t N>(auto& generator, char const(&text)[N]) -> ErrorOr<void> {
diff --git a/Meta/Lagom/Tools/CodeGenerators/IPCCompiler/main.cpp b/Meta/Lagom/Tools/CodeGenerators/IPCCompiler/main.cpp
index 38ecd49d14d..f7b03c3ba0a 100644
--- a/Meta/Lagom/Tools/CodeGenerators/IPCCompiler/main.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/IPCCompiler/main.cpp
@@ -17,12 +17,12 @@
 #include <stdio.h>
 
 struct Parameter {
-    Vector<DeprecatedString> attributes;
-    DeprecatedString type;
-    DeprecatedString name;
+    Vector<ByteString> attributes;
+    ByteString type;
+    ByteString name;
 };
 
-static DeprecatedString pascal_case(DeprecatedString const& identifier)
+static ByteString pascal_case(ByteString const& identifier)
 {
     StringBuilder builder;
     bool was_new_word = true;
@@ -37,48 +37,48 @@ static DeprecatedString pascal_case(DeprecatedString const& identifier)
         } else
             builder.append(ch);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 struct Message {
-    DeprecatedString name;
+    ByteString name;
     bool is_synchronous { false };
     Vector<Parameter> inputs;
     Vector<Parameter> outputs;
 
-    DeprecatedString response_name() const
+    ByteString response_name() const
     {
         StringBuilder builder;
         builder.append(pascal_case(name));
         builder.append("Response"sv);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 };
 
 struct Endpoint {
-    Vector<DeprecatedString> includes;
-    DeprecatedString name;
+    Vector<ByteString> includes;
+    ByteString name;
     u32 magic;
     Vector<Message> messages;
 };
 
-static bool is_primitive_type(DeprecatedString const& type)
+static bool is_primitive_type(ByteString const& type)
 {
     return type.is_one_of("u8", "i8", "u16", "i16", "u32", "i32", "u64", "i64", "size_t", "bool", "double", "float", "int", "unsigned", "unsigned int");
 }
 
-static bool is_simple_type(DeprecatedString const& type)
+static bool is_simple_type(ByteString const& type)
 {
     // Small types that it makes sense just to pass by value.
     return type.is_one_of("Gfx::Color", "Web::DevicePixels", "Gfx::IntPoint", "Gfx::FloatPoint", "Web::DevicePixelPoint", "Gfx::IntSize", "Gfx::FloatSize", "Web::DevicePixelSize", "Core::File::OpenMode");
 }
 
-static bool is_primitive_or_simple_type(DeprecatedString const& type)
+static bool is_primitive_or_simple_type(ByteString const& type)
 {
     return is_primitive_type(type) || is_simple_type(type);
 }
 
-static DeprecatedString message_name(DeprecatedString const& endpoint, DeprecatedString const& message, bool is_response)
+static ByteString message_name(ByteString const& endpoint, ByteString const& message, bool is_response)
 {
     StringBuilder builder;
     builder.append("Messages::"sv);
@@ -87,7 +87,7 @@ static DeprecatedString message_name(DeprecatedString const& endpoint, Deprecate
     builder.append(pascal_case(message));
     if (is_response)
         builder.append("Response"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 Vector<Endpoint> parse(ByteBuffer const& file_contents)
@@ -133,7 +133,7 @@ Vector<Endpoint> parse(ByteBuffer const& file_contents)
                     consume_whitespace();
                 }
             }
-            // FIXME: This is not entirely correct. Types can have spaces, for example `HashMap<int, DeprecatedString>`.
+            // FIXME: This is not entirely correct. Types can have spaces, for example `HashMap<int, ByteString>`.
             //        Maybe we should use LibCpp::Parser for parsing types.
             parameter.type = lexer.consume_until([](char ch) { return isspace(ch); });
             if (parameter.type.ends_with(',')) {
@@ -208,7 +208,7 @@ Vector<Endpoint> parse(ByteBuffer const& file_contents)
     };
 
     auto parse_include = [&] {
-        DeprecatedString include;
+        ByteString include;
         consume_whitespace();
         include = lexer.consume_while([](char ch) { return ch != '\n'; });
         consume_whitespace();
@@ -234,7 +234,7 @@ Vector<Endpoint> parse(ByteBuffer const& file_contents)
         lexer.consume_specific("endpoint");
         consume_whitespace();
         endpoints.last().name = lexer.consume_while([](char ch) { return !isspace(ch); });
-        endpoints.last().magic = Traits<DeprecatedString>::hash(endpoints.last().name);
+        endpoints.last().magic = Traits<ByteString>::hash(endpoints.last().name);
         consume_whitespace();
         assert_specific('{');
         parse_messages();
@@ -248,22 +248,22 @@ Vector<Endpoint> parse(ByteBuffer const& file_contents)
     return endpoints;
 }
 
-HashMap<DeprecatedString, int> build_message_ids_for_endpoint(SourceGenerator generator, Endpoint const& endpoint)
+HashMap<ByteString, int> build_message_ids_for_endpoint(SourceGenerator generator, Endpoint const& endpoint)
 {
-    HashMap<DeprecatedString, int> message_ids;
+    HashMap<ByteString, int> message_ids;
 
     generator.appendln("\nenum class MessageID : i32 {");
     for (auto const& message : endpoint.messages) {
 
         message_ids.set(message.name, message_ids.size() + 1);
         generator.set("message.pascal_name", pascal_case(message.name));
-        generator.set("message.id", DeprecatedString::number(message_ids.size()));
+        generator.set("message.id", ByteString::number(message_ids.size()));
 
         generator.appendln("    @message.pascal_name@ = @message.id@,");
         if (message.is_synchronous) {
             message_ids.set(message.response_name(), message_ids.size() + 1);
             generator.set("message.pascal_name", pascal_case(message.response_name()));
-            generator.set("message.id", DeprecatedString::number(message_ids.size()));
+            generator.set("message.id", ByteString::number(message_ids.size()));
 
             generator.appendln("    @message.pascal_name@ = @message.id@,");
         }
@@ -272,14 +272,14 @@ HashMap<DeprecatedString, int> build_message_ids_for_endpoint(SourceGenerator ge
     return message_ids;
 }
 
-DeprecatedString constructor_for_message(DeprecatedString const& name, Vector<Parameter> const& parameters)
+ByteString constructor_for_message(ByteString const& name, Vector<Parameter> const& parameters)
 {
     StringBuilder builder;
     builder.append(name);
 
     if (parameters.is_empty()) {
         builder.append("() {}"sv);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
     builder.append('(');
     for (size_t i = 0; i < parameters.size(); ++i) {
@@ -296,10 +296,10 @@ DeprecatedString constructor_for_message(DeprecatedString const& name, Vector<Pa
             builder.append(", "sv);
     }
     builder.append(" {}"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-void do_message(SourceGenerator message_generator, DeprecatedString const& name, Vector<Parameter> const& parameters, DeprecatedString const& response_type = {})
+void do_message(SourceGenerator message_generator, ByteString const& name, Vector<Parameter> const& parameters, ByteString const& response_type = {})
 {
     auto pascal_name = pascal_case(name);
     message_generator.set("message.name", name);
@@ -377,7 +377,7 @@ public:)~~~");
             builder.append(", "sv);
     }
 
-    message_generator.set("message.constructor_call_parameters", builder.to_deprecated_string());
+    message_generator.set("message.constructor_call_parameters", builder.to_byte_string());
     message_generator.appendln(R"~~~(
         return make<@message.pascal_name@>(@message.constructor_call_parameters@);
     })~~~");
@@ -432,17 +432,17 @@ private:
 
 void do_message_for_proxy(SourceGenerator message_generator, Endpoint const& endpoint, Message const& message)
 {
-    auto do_implement_proxy = [&](DeprecatedString const& name, Vector<Parameter> const& parameters, bool is_synchronous, bool is_try) {
-        DeprecatedString return_type = "void";
+    auto do_implement_proxy = [&](ByteString const& name, Vector<Parameter> const& parameters, bool is_synchronous, bool is_try) {
+        ByteString return_type = "void";
         if (is_synchronous) {
             if (message.outputs.size() == 1)
                 return_type = message.outputs[0].type;
             else if (!message.outputs.is_empty())
                 return_type = message_name(endpoint.name, message.name, true);
         }
-        DeprecatedString inner_return_type = return_type;
+        ByteString inner_return_type = return_type;
         if (is_try)
-            return_type = DeprecatedString::formatted("IPC::IPCErrorOr<{}>", return_type);
+            return_type = ByteString::formatted("IPC::IPCErrorOr<{}>", return_type);
 
         message_generator.set("message.name", message.name);
         message_generator.set("message.pascal_name", pascal_case(message.name));
@@ -541,14 +541,14 @@ void do_message_for_proxy(SourceGenerator message_generator, Endpoint const& end
 void build_endpoint(SourceGenerator generator, Endpoint const& endpoint)
 {
     generator.set("endpoint.name", endpoint.name);
-    generator.set("endpoint.magic", DeprecatedString::number(endpoint.magic));
+    generator.set("endpoint.magic", ByteString::number(endpoint.magic));
 
     generator.appendln("\nnamespace Messages::@endpoint.name@ {");
 
-    HashMap<DeprecatedString, int> message_ids = build_message_ids_for_endpoint(generator.fork(), endpoint);
+    HashMap<ByteString, int> message_ids = build_message_ids_for_endpoint(generator.fork(), endpoint);
 
     for (auto const& message : endpoint.messages) {
-        DeprecatedString response_name;
+        ByteString response_name;
         if (message.is_synchronous) {
             response_name = message.response_name();
             do_message(generator.fork(), response_name, message.outputs);
@@ -611,7 +611,7 @@ public:
         switch (message_id) {)~~~");
 
     for (auto const& message : endpoint.messages) {
-        auto do_decode_message = [&](DeprecatedString const& name) {
+        auto do_decode_message = [&](ByteString const& name) {
             auto message_generator = generator.fork();
 
             message_generator.set("message.name", name);
@@ -649,13 +649,13 @@ public:
     virtual ~@endpoint.name@Stub() override { }
 
     virtual u32 magic() const override { return @endpoint.magic@; }
-    virtual DeprecatedString name() const override { return "@endpoint.name@"; }
+    virtual ByteString name() const override { return "@endpoint.name@"; }
 
     virtual ErrorOr<OwnPtr<IPC::MessageBuffer>> handle(const IPC::Message& message) override
     {
         switch (message.message_id()) {)~~~");
     for (auto const& message : endpoint.messages) {
-        auto do_handle_message = [&](DeprecatedString const& name, Vector<Parameter> const& parameters, bool returns_something) {
+        auto do_handle_message = [&](ByteString const& name, Vector<Parameter> const& parameters, bool returns_something) {
             auto message_generator = generator.fork();
 
             StringBuilder argument_generator;
@@ -671,7 +671,7 @@ public:
             message_generator.set("message.pascal_name", pascal_case(name));
             message_generator.set("message.response_type", pascal_case(message.response_name()));
             message_generator.set("handler_name", name);
-            message_generator.set("arguments", argument_generator.to_deprecated_string());
+            message_generator.set("arguments", argument_generator.to_byte_string());
             message_generator.appendln(R"~~~(
         case (int)Messages::@endpoint.name@::MessageID::@message.pascal_name@: {)~~~");
             if (returns_something) {
@@ -709,8 +709,8 @@ public:
     for (auto const& message : endpoint.messages) {
         auto message_generator = generator.fork();
 
-        auto do_handle_message_decl = [&](DeprecatedString const& name, Vector<Parameter> const& parameters, bool is_response) {
-            DeprecatedString return_type = "void";
+        auto do_handle_message_decl = [&](ByteString const& name, Vector<Parameter> const& parameters, bool is_response) {
+            ByteString return_type = "void";
             if (message.is_synchronous && !message.outputs.is_empty() && !is_response)
                 return_type = message_name(endpoint.name, message.name, true);
             message_generator.set("message.complex_return_type", return_type);
@@ -719,7 +719,7 @@ public:
             message_generator.appendln(R"~~~(
     virtual @message.complex_return_type@ @handler_name@()~~~");
 
-            auto make_argument_type = [](DeprecatedString const& type) {
+            auto make_argument_type = [](ByteString const& type) {
                 StringBuilder builder;
 
                 bool const_ref = !is_primitive_or_simple_type(type);
@@ -728,7 +728,7 @@ public:
                 if (const_ref)
                     builder.append(" const&"sv);
 
-                return builder.to_deprecated_string();
+                return builder.to_byte_string();
             };
 
             for (size_t i = 0; i < parameters.size(); ++i) {
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibGL/GenerateGLAPIWrapper.cpp b/Meta/Lagom/Tools/CodeGenerators/LibGL/GenerateGLAPIWrapper.cpp
index 3ece80aa631..1357cb0f780 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibGL/GenerateGLAPIWrapper.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibGL/GenerateGLAPIWrapper.cpp
@@ -5,7 +5,7 @@
  */
 
 #include <AK/Array.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/JsonObject.h>
 #include <AK/NumericLimits.h>
 #include <AK/Optional.h>
@@ -18,40 +18,40 @@
 #include <LibMain/Main.h>
 
 struct ArgumentDefinition {
-    Optional<DeprecatedString> name;
-    Optional<DeprecatedString> cpp_type;
-    DeprecatedString expression;
-    Optional<DeprecatedString> cast_to;
+    Optional<ByteString> name;
+    Optional<ByteString> cpp_type;
+    ByteString expression;
+    Optional<ByteString> cast_to;
 };
 
 struct FunctionDefinition {
-    DeprecatedString name;
-    DeprecatedString return_type;
+    ByteString name;
+    ByteString return_type;
     Vector<ArgumentDefinition> arguments;
-    DeprecatedString implementation;
+    ByteString implementation;
     bool unimplemented;
-    DeprecatedString variant_gl_type;
+    ByteString variant_gl_type;
 };
 
 struct VariantType {
-    DeprecatedString encoded_type;
-    Optional<DeprecatedString> implementation;
+    ByteString encoded_type;
+    Optional<ByteString> implementation;
     bool unimplemented;
 };
 
 struct Variants {
-    Vector<DeprecatedString> api_suffixes { "" };
+    Vector<ByteString> api_suffixes { "" };
     Vector<u32> argument_counts { NumericLimits<u32>::max() };
-    Vector<DeprecatedString> argument_defaults { "" };
+    Vector<ByteString> argument_defaults { "" };
     bool convert_range { false };
     Vector<VariantType> types {
         {
             .encoded_type = "",
-            .implementation = Optional<DeprecatedString> {},
+            .implementation = Optional<ByteString> {},
             .unimplemented = false,
         }
     };
-    DeprecatedString pointer_argument { "" };
+    ByteString pointer_argument { "" };
 };
 
 struct EncodedTypeEntry {
@@ -76,18 +76,18 @@ constexpr static Array<EncodedTypeEntry, 9> type_definitions = {
 
 struct EncodedType {
     EncodedTypeEntry type_entry;
-    DeprecatedString cpp_type;
-    DeprecatedString function_name_suffix;
+    ByteString cpp_type;
+    ByteString function_name_suffix;
     bool is_pointer;
     bool is_const_pointer;
 };
 
-Vector<DeprecatedString> get_name_list(Optional<JsonValue const&> name_definition)
+Vector<ByteString> get_name_list(Optional<JsonValue const&> name_definition)
 {
     if (!name_definition.has_value() || name_definition->is_null())
         return {};
 
-    Vector<DeprecatedString, 1> names;
+    Vector<ByteString, 1> names;
     if (name_definition->is_string()) {
         names.append(name_definition->as_string());
     } else if (name_definition->is_array()) {
@@ -101,12 +101,12 @@ Vector<DeprecatedString> get_name_list(Optional<JsonValue const&> name_definitio
     return names;
 }
 
-Optional<EncodedType> get_encoded_type(DeprecatedString encoded_type)
+Optional<EncodedType> get_encoded_type(ByteString encoded_type)
 {
     bool is_const_pointer = !encoded_type.ends_with('!');
     if (!is_const_pointer)
         encoded_type = encoded_type.substring_view(0, encoded_type.length() - 1);
-    DeprecatedString function_name_suffix = encoded_type;
+    ByteString function_name_suffix = encoded_type;
 
     bool is_pointer = encoded_type.ends_with('v');
     if (is_pointer)
@@ -127,7 +127,7 @@ Optional<EncodedType> get_encoded_type(DeprecatedString encoded_type)
 
     return EncodedType {
         .type_entry = type_definition.value(),
-        .cpp_type = DeprecatedString::formatted(
+        .cpp_type = ByteString::formatted(
             "{}{}{}",
             type_definition->cpp_type,
             is_pointer && is_const_pointer ? " const" : "",
@@ -138,7 +138,7 @@ Optional<EncodedType> get_encoded_type(DeprecatedString encoded_type)
     };
 }
 
-DeprecatedString wrap_expression_in_range_conversion(DeprecatedString source_type, DeprecatedString target_type, DeprecatedString expression)
+ByteString wrap_expression_in_range_conversion(ByteString source_type, ByteString target_type, ByteString expression)
 {
     VERIFY(target_type == "GLfloat" || target_type == "GLdouble");
 
@@ -147,19 +147,19 @@ DeprecatedString wrap_expression_in_range_conversion(DeprecatedString source_typ
         return expression;
 
     if (source_type == "GLbyte")
-        return DeprecatedString::formatted("({} + 128.) / 127.5 - 1.", expression);
+        return ByteString::formatted("({} + 128.) / 127.5 - 1.", expression);
     else if (source_type == "GLfloat")
-        return DeprecatedString::formatted("static_cast<GLdouble>({})", expression);
+        return ByteString::formatted("static_cast<GLdouble>({})", expression);
     else if (source_type == "GLint")
-        return DeprecatedString::formatted("({} + 2147483648.) / 2147483647.5 - 1.", expression);
+        return ByteString::formatted("({} + 2147483648.) / 2147483647.5 - 1.", expression);
     else if (source_type == "GLshort")
-        return DeprecatedString::formatted("({} + 32768.) / 32767.5 - 1.", expression);
+        return ByteString::formatted("({} + 32768.) / 32767.5 - 1.", expression);
     else if (source_type == "GLubyte")
-        return DeprecatedString::formatted("{} / 255.", expression);
+        return ByteString::formatted("{} / 255.", expression);
     else if (source_type == "GLuint")
-        return DeprecatedString::formatted("{} / 4294967296.", expression);
+        return ByteString::formatted("{} / 4294967296.", expression);
     else if (source_type == "GLushort")
-        return DeprecatedString::formatted("{} / 65536.", expression);
+        return ByteString::formatted("{} / 65536.", expression);
     VERIFY_NOT_REACHED();
 }
 
@@ -189,7 +189,7 @@ Variants read_variants_settings(JsonObject const& variants_obj)
         });
     }
     if (variants_obj.has_string("pointer_argument"sv)) {
-        variants.pointer_argument = variants_obj.get_deprecated_string("pointer_argument"sv).value();
+        variants.pointer_argument = variants_obj.get_byte_string("pointer_argument"sv).value();
     }
     if (variants_obj.has_object("types"sv)) {
         variants.types.clear_with_capacity();
@@ -197,7 +197,7 @@ Variants read_variants_settings(JsonObject const& variants_obj)
             auto const& type = type_value.as_object();
             variants.types.append(VariantType {
                 .encoded_type = key,
-                .implementation = type.get_deprecated_string("implementation"sv),
+                .implementation = type.get_byte_string("implementation"sv),
                 .unimplemented = type.get_bool("unimplemented"sv).value_or(false),
             });
         });
@@ -223,20 +223,20 @@ Vector<ArgumentDefinition> copy_arguments_for_variant(Vector<ArgumentDefinition>
 
         // Pointer argument
         if (encoded_type.is_pointer) {
-            variant_arguments[i].name = (variadic_index == 0) ? variants.pointer_argument : Optional<DeprecatedString> {};
+            variant_arguments[i].name = (variadic_index == 0) ? variants.pointer_argument : Optional<ByteString> {};
 
             if (variadic_index >= argument_count) {
                 // If this variable argument is past the argument count, fall back to the defaults
                 variant_arguments[i].expression = variants.argument_defaults[variadic_index];
-                variant_arguments[i].cast_to = Optional<DeprecatedString> {};
+                variant_arguments[i].cast_to = Optional<ByteString> {};
 
             } else if (argument_count == 1 && variants.argument_counts.size() == 1) {
                 // Otherwise, if the pointer is the only variadic argument, pass it through unchanged
-                variant_arguments[i].cast_to = Optional<DeprecatedString> {};
+                variant_arguments[i].cast_to = Optional<ByteString> {};
 
             } else {
                 // Otherwise, index into the pointer argument
-                auto indexed_expression = DeprecatedString::formatted("{}[{}]", variants.pointer_argument, variadic_index);
+                auto indexed_expression = ByteString::formatted("{}[{}]", variants.pointer_argument, variadic_index);
                 if (variants.convert_range && cast_to.has_value())
                     indexed_expression = wrap_expression_in_range_conversion(base_cpp_type, cast_to.value(), indexed_expression);
                 variant_arguments[i].expression = indexed_expression;
@@ -246,9 +246,9 @@ Vector<ArgumentDefinition> copy_arguments_for_variant(Vector<ArgumentDefinition>
             // Regular argument
             if (variadic_index >= argument_count) {
                 // If the variable argument is past the argument count, fall back to the defaults
-                variant_arguments[i].name = Optional<DeprecatedString> {};
+                variant_arguments[i].name = Optional<ByteString> {};
                 variant_arguments[i].expression = variants.argument_defaults[variadic_index];
-                variant_arguments[i].cast_to = Optional<DeprecatedString> {};
+                variant_arguments[i].cast_to = Optional<ByteString> {};
 
             } else if (variants.convert_range && cast_to.has_value()) {
                 // Otherwise, if we need to convert the input values, wrap the expression in a range conversion
@@ -261,7 +261,7 @@ Vector<ArgumentDefinition> copy_arguments_for_variant(Vector<ArgumentDefinition>
 
         // Determine if we can skip casting to the target type
         if (cast_to == base_cpp_type || (variants.convert_range && cast_to == "GLdouble"))
-            variant_arguments[i].cast_to = Optional<DeprecatedString> {};
+            variant_arguments[i].cast_to = Optional<ByteString> {};
 
         variadic_index++;
     }
@@ -269,7 +269,7 @@ Vector<ArgumentDefinition> copy_arguments_for_variant(Vector<ArgumentDefinition>
     return variant_arguments;
 }
 
-Vector<FunctionDefinition> create_function_definitions(DeprecatedString function_name, JsonObject const& function_definition)
+Vector<FunctionDefinition> create_function_definitions(ByteString function_name, JsonObject const& function_definition)
 {
     // A single function definition can expand to multiple generated functions by way of:
     //   - differing API suffices (ARB, EXT, etc.);
@@ -284,17 +284,17 @@ Vector<FunctionDefinition> create_function_definitions(DeprecatedString function
         VERIFY(argument_value.is_object());
         auto const& argument = argument_value.as_object();
 
-        auto type = argument.get_deprecated_string("type"sv);
+        auto type = argument.get_byte_string("type"sv);
         auto argument_names = get_name_list(argument.get("name"sv));
-        auto expression = argument.get_deprecated_string("expression"sv).value_or("@argument_name@");
-        auto cast_to = argument.get_deprecated_string("cast_to"sv);
+        auto expression = argument.get_byte_string("expression"sv).value_or("@argument_name@");
+        auto cast_to = argument.get_byte_string("cast_to"sv);
 
         // Add an empty dummy name when all we have is an expression
         if (argument_names.is_empty() && !expression.is_empty())
             argument_names.append("");
 
         for (auto const& argument_name : argument_names) {
-            argument_definitions.append({ .name = argument_name.is_empty() ? Optional<DeprecatedString> {} : argument_name,
+            argument_definitions.append({ .name = argument_name.is_empty() ? Optional<ByteString> {} : argument_name,
                 .cpp_type = type,
                 .expression = expression,
                 .cast_to = cast_to });
@@ -304,8 +304,8 @@ Vector<FunctionDefinition> create_function_definitions(DeprecatedString function
     // Create functions for each name and/or variant
     Vector<FunctionDefinition> functions;
 
-    auto return_type = function_definition.get_deprecated_string("return_type"sv).value_or("void");
-    auto function_implementation = function_definition.get_deprecated_string("implementation"sv).value_or(function_name.to_snakecase());
+    auto return_type = function_definition.get_byte_string("return_type"sv).value_or("void");
+    auto function_implementation = function_definition.get_byte_string("implementation"sv).value_or(function_name.to_snakecase());
     auto function_unimplemented = function_definition.get_bool("unimplemented"sv).value_or(false);
 
     if (!function_definition.has("variants"sv)) {
@@ -336,10 +336,10 @@ Vector<FunctionDefinition> create_function_definitions(DeprecatedString function
 
             for (auto const& api_suffix : variants.api_suffixes) {
                 functions.append({
-                    .name = DeprecatedString::formatted(
+                    .name = ByteString::formatted(
                         "{}{}{}{}",
                         function_name,
-                        variants.argument_counts.size() > 1 ? DeprecatedString::formatted("{}", argument_count) : "",
+                        variants.argument_counts.size() > 1 ? ByteString::formatted("{}", argument_count) : "",
                         encoded_type.has_value() && variants.types.size() > 1 ? encoded_type->function_name_suffix : "",
                         api_suffix),
                     .return_type = return_type,
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateDateTimeFormatData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateDateTimeFormatData.cpp
index 44789917ff1..1d8e05ae509 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateDateTimeFormatData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateDateTimeFormatData.cpp
@@ -6,8 +6,8 @@
 
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
 #include <AK/AllOf.h>
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Error.h>
 #include <AK/Find.h>
 #include <AK/Format.h>
@@ -487,7 +487,7 @@ struct AK::Formatter<Locale::HourCycle> : Formatter<FormatString> {
 };
 
 struct LocaleData {
-    HashMap<DeprecatedString, size_t> calendars;
+    HashMap<ByteString, size_t> calendars;
 
     size_t time_zones { 0 };
     size_t time_zone_formats { 0 };
@@ -513,27 +513,27 @@ struct CLDR {
     UniqueStorage<DayPeriodList> unique_day_period_lists;
     UniqueStorage<HourCycleList> unique_hour_cycle_lists;
 
-    HashMap<DeprecatedString, LocaleData> locales;
+    HashMap<ByteString, LocaleData> locales;
 
-    HashMap<DeprecatedString, size_t> hour_cycles;
-    Vector<DeprecatedString> hour_cycle_regions;
+    HashMap<ByteString, size_t> hour_cycles;
+    Vector<ByteString> hour_cycle_regions;
 
-    HashMap<DeprecatedString, u8> minimum_days;
-    Vector<DeprecatedString> minimum_days_regions;
+    HashMap<ByteString, u8> minimum_days;
+    Vector<ByteString> minimum_days_regions;
 
-    HashMap<DeprecatedString, Locale::Weekday> first_day;
-    Vector<DeprecatedString> first_day_regions;
+    HashMap<ByteString, Locale::Weekday> first_day;
+    Vector<ByteString> first_day_regions;
 
-    HashMap<DeprecatedString, Locale::Weekday> weekend_start;
-    Vector<DeprecatedString> weekend_start_regions;
+    HashMap<ByteString, Locale::Weekday> weekend_start;
+    Vector<ByteString> weekend_start_regions;
 
-    HashMap<DeprecatedString, Locale::Weekday> weekend_end;
-    Vector<DeprecatedString> weekend_end_regions;
+    HashMap<ByteString, Locale::Weekday> weekend_end;
+    Vector<ByteString> weekend_end_regions;
 
-    HashMap<DeprecatedString, Vector<TimeZone::TimeZone>> meta_zones;
-    Vector<DeprecatedString> time_zones { "UTC"sv };
+    HashMap<ByteString, Vector<TimeZone::TimeZone>> meta_zones;
+    Vector<ByteString> time_zones { "UTC"sv };
 
-    Vector<DeprecatedString> calendars;
+    Vector<ByteString> calendars;
 };
 
 static Optional<Locale::DayPeriod> day_period_from_string(StringView day_period)
@@ -563,7 +563,7 @@ static Optional<Locale::DayPeriod> day_period_from_string(StringView day_period)
     return {};
 }
 
-static ErrorOr<void> parse_hour_cycles(DeprecatedString core_path, CLDR& cldr)
+static ErrorOr<void> parse_hour_cycles(ByteString core_path, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Time_Data
     LexicalPath time_data_path(move(core_path));
@@ -587,7 +587,7 @@ static ErrorOr<void> parse_hour_cycles(DeprecatedString core_path, CLDR& cldr)
     };
 
     time_data_object.for_each_member([&](auto const& key, JsonValue const& value) {
-        auto allowed_hour_cycles_string = value.as_object().get_deprecated_string("_allowed"sv).value();
+        auto allowed_hour_cycles_string = value.as_object().get_byte_string("_allowed"sv).value();
         auto allowed_hour_cycles = allowed_hour_cycles_string.split_view(' ');
 
         Vector<Locale::HourCycle> hour_cycles;
@@ -607,7 +607,7 @@ static ErrorOr<void> parse_hour_cycles(DeprecatedString core_path, CLDR& cldr)
     return {};
 }
 
-static ErrorOr<void> parse_week_data(DeprecatedString core_path, CLDR& cldr)
+static ErrorOr<void> parse_week_data(ByteString core_path, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Week_Data
     LexicalPath week_data_path(move(core_path));
@@ -672,7 +672,7 @@ static ErrorOr<void> parse_week_data(DeprecatedString core_path, CLDR& cldr)
     return {};
 }
 
-static ErrorOr<void> parse_meta_zones(DeprecatedString core_path, CLDR& cldr)
+static ErrorOr<void> parse_meta_zones(ByteString core_path, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Metazones
     LexicalPath meta_zone_path(move(core_path));
@@ -686,8 +686,8 @@ static ErrorOr<void> parse_meta_zones(DeprecatedString core_path, CLDR& cldr)
 
     meta_zone_array.for_each([&](JsonValue const& value) {
         auto const& mapping = value.as_object().get_object("mapZone"sv).value();
-        auto const& meta_zone = mapping.get_deprecated_string("_other"sv).value();
-        auto const& golden_zone = mapping.get_deprecated_string("_type"sv).value();
+        auto const& meta_zone = mapping.get_byte_string("_other"sv).value();
+        auto const& golden_zone = mapping.get_byte_string("_type"sv).value();
 
         if (auto time_zone = TimeZone::time_zone_from_string(golden_zone); time_zone.has_value()) {
             auto& golden_zones = cldr.meta_zones.ensure(meta_zone);
@@ -770,7 +770,7 @@ static ErrorOr<String> remove_period_from_pattern(String pattern)
     return pattern;
 }
 
-static ErrorOr<Optional<CalendarPattern>> parse_date_time_pattern_raw(DeprecatedString pattern, DeprecatedString skeleton, CLDR& cldr)
+static ErrorOr<Optional<CalendarPattern>> parse_date_time_pattern_raw(ByteString pattern, ByteString skeleton, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table
     using Locale::CalendarPatternStyle;
@@ -989,16 +989,16 @@ static ErrorOr<Optional<CalendarPattern>> parse_date_time_pattern_raw(Deprecated
     return format;
 }
 
-static ErrorOr<Optional<size_t>> parse_date_time_pattern(DeprecatedString pattern, DeprecatedString skeleton, CLDR& cldr)
+static ErrorOr<Optional<size_t>> parse_date_time_pattern(ByteString pattern, ByteString skeleton, CLDR& cldr)
 {
     auto format = TRY(parse_date_time_pattern_raw(move(pattern), move(skeleton), cldr));
     if (!format.has_value())
         return OptionalNone {};
 
-    format->pattern_index = cldr.unique_strings.ensure(format->pattern.to_deprecated_string());
+    format->pattern_index = cldr.unique_strings.ensure(format->pattern.to_byte_string());
 
     if (format->pattern12.has_value())
-        format->pattern12_index = cldr.unique_strings.ensure(format->pattern12->to_deprecated_string());
+        format->pattern12_index = cldr.unique_strings.ensure(format->pattern12->to_byte_string());
 
     return Optional<size_t> { cldr.unique_patterns.ensure(format.release_value()) };
 }
@@ -1388,7 +1388,7 @@ static void parse_calendar_symbols(Calendar& calendar, JsonObject const& calenda
     calendar.symbols = cldr.unique_calendar_symbols_lists.ensure(move(symbols_list));
 }
 
-static ErrorOr<void> parse_calendars(DeprecatedString locale_calendars_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_calendars(ByteString locale_calendars_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath calendars_path(move(locale_calendars_path));
     if (!calendars_path.basename().starts_with("ca-"sv))
@@ -1402,10 +1402,10 @@ static ErrorOr<void> parse_calendars(DeprecatedString locale_calendars_path, CLD
 
     auto parse_patterns = [&](auto const& patterns_object, auto const& skeletons_object, Vector<CalendarPattern>* patterns) -> ErrorOr<size_t> {
         auto parse_pattern = [&](auto name) -> ErrorOr<size_t> {
-            auto format = patterns_object.get_deprecated_string(name);
-            auto skeleton = skeletons_object.get_deprecated_string(name);
+            auto format = patterns_object.get_byte_string(name);
+            auto skeleton = skeletons_object.get_byte_string(name);
 
-            auto format_index = TRY(parse_date_time_pattern(format.value(), skeleton.value_or(DeprecatedString::empty()), cldr)).value();
+            auto format_index = TRY(parse_date_time_pattern(format.value(), skeleton.value_or(ByteString::empty()), cldr)).value();
 
             if (patterns)
                 patterns->append(cldr.unique_patterns.get(format_index));
@@ -1483,7 +1483,7 @@ static ErrorOr<void> parse_calendars(DeprecatedString locale_calendars_path, CLD
     return {};
 }
 
-static ErrorOr<void> parse_time_zone_names(DeprecatedString locale_time_zone_names_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_time_zone_names(ByteString locale_time_zone_names_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath time_zone_names_path(move(locale_time_zone_names_path));
     time_zone_names_path = time_zone_names_path.append("timeZoneNames.json"sv);
@@ -1494,9 +1494,9 @@ static ErrorOr<void> parse_time_zone_names(DeprecatedString locale_time_zone_nam
     auto const& dates_object = locale_object.get_object("dates"sv).value();
     auto const& time_zone_names_object = dates_object.get_object("timeZoneNames"sv).value();
     auto const& meta_zone_object = time_zone_names_object.get_object("metazone"sv);
-    auto const& hour_format_string = time_zone_names_object.get_deprecated_string("hourFormat"sv).value();
-    auto const& gmt_format_string = time_zone_names_object.get_deprecated_string("gmtFormat"sv).value();
-    auto const& gmt_zero_format_string = time_zone_names_object.get_deprecated_string("gmtZeroFormat"sv).value();
+    auto const& hour_format_string = time_zone_names_object.get_byte_string("hourFormat"sv).value();
+    auto const& gmt_format_string = time_zone_names_object.get_byte_string("gmtFormat"sv).value();
+    auto const& gmt_zero_format_string = time_zone_names_object.get_byte_string("gmtZeroFormat"sv).value();
 
     if (!meta_zone_object.has_value())
         return {};
@@ -1506,7 +1506,7 @@ static ErrorOr<void> parse_time_zone_names(DeprecatedString locale_time_zone_nam
         if (!names.has_value())
             return {};
 
-        auto const& name = names->get_deprecated_string(key);
+        auto const& name = names->get_byte_string(key);
         if (name.has_value())
             return cldr.unique_strings.ensure(name.value());
 
@@ -1592,7 +1592,7 @@ static ErrorOr<void> parse_time_zone_names(DeprecatedString locale_time_zone_nam
     return {};
 }
 
-static ErrorOr<void> parse_day_periods(DeprecatedString core_path, CLDR& cldr)
+static ErrorOr<void> parse_day_periods(ByteString core_path, CLDR& cldr)
 {
     // https://unicode.org/reports/tr35/tr35-dates.html#Day_Period_Rule_Sets
     LexicalPath day_periods_path(move(core_path));
@@ -1622,8 +1622,8 @@ static ErrorOr<void> parse_day_periods(DeprecatedString core_path, CLDR& cldr)
         if (!day_period.has_value())
             return {};
 
-        auto begin = parse_hour(ranges.get_deprecated_string("_from"sv).value());
-        auto end = parse_hour(ranges.get_deprecated_string("_before"sv).value());
+        auto begin = parse_hour(ranges.get_byte_string("_from"sv).value());
+        auto end = parse_hour(ranges.get_byte_string("_before"sv).value());
 
         return DayPeriod { *day_period, begin, end };
     };
@@ -1648,13 +1648,13 @@ static ErrorOr<void> parse_day_periods(DeprecatedString core_path, CLDR& cldr)
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedString dates_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(ByteString core_path, ByteString dates_path, CLDR& cldr)
 {
     TRY(parse_hour_cycles(core_path, cldr));
     TRY(parse_week_data(core_path, cldr));
     TRY(parse_meta_zones(core_path, cldr));
 
-    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
+    auto remove_variants_from_path = [&](ByteString path) -> ErrorOr<ByteString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -1664,7 +1664,7 @@ static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedStr
         if (auto region = cldr.unique_strings.get(parsed_locale.region); !region.is_empty())
             builder.appendff("-{}", region);
 
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
 
     TRY(Core::Directory::for_each_entry(TRY(String::formatted("{}/main", dates_path)), Core::DirIterator::SkipParentAndBaseDir, [&](auto& entry, auto& directory) -> ErrorOr<IterationDecision> {
@@ -1687,15 +1687,15 @@ static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedStr
     return {};
 }
 
-static DeprecatedString format_identifier(StringView owner, DeprecatedString identifier)
+static ByteString format_identifier(StringView owner, ByteString identifier)
 {
     identifier = identifier.replace("-"sv, "_"sv, ReplaceMode::All);
     identifier = identifier.replace("/"sv, "_"sv, ReplaceMode::All);
 
     if (all_of(identifier, is_ascii_digit))
-        return DeprecatedString::formatted("{}_{}", owner[0], identifier);
+        return ByteString::formatted("{}_{}", owner[0], identifier);
     if (is_ascii_lower_alpha(identifier[0]))
-        return DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
+        return ByteString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
     return identifier;
 }
 
@@ -1953,9 +1953,9 @@ struct DayPeriodData {
     cldr.unique_day_period_lists.generate(generator, cldr.unique_day_periods.type_that_fits(), "s_day_period_lists"sv);
     cldr.unique_hour_cycle_lists.generate(generator, cldr.unique_hour_cycle_lists.type_that_fits(), "s_hour_cycle_lists"sv);
 
-    auto append_calendars = [&](DeprecatedString name, auto const& calendars) {
+    auto append_calendars = [&](ByteString name, auto const& calendars) {
         generator.set("name", name);
-        generator.set("size", DeprecatedString::number(calendars.size()));
+        generator.set("size", ByteString::number(calendars.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@calendar_index_type@, @size@> @name@ { {)~~~");
@@ -1965,7 +1965,7 @@ static constexpr Array<@calendar_index_type@, @size@> @name@ { {)~~~");
             auto calendar = calendars.find(calendar_key)->value;
 
             generator.append(first ? " "sv : ", "sv);
-            generator.append(DeprecatedString::number(calendar));
+            generator.append(ByteString::number(calendar));
             first = false;
         }
 
@@ -1975,7 +1975,7 @@ static constexpr Array<@calendar_index_type@, @size@> @name@ { {)~~~");
     auto append_mapping = [&](auto const& keys, auto const& map, auto type, auto name, auto mapping_getter) {
         generator.set("type", type);
         generator.set("name", name);
-        generator.set("size", DeprecatedString::number(keys.size()));
+        generator.set("size", ByteString::number(keys.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {)~~~");
@@ -1986,7 +1986,7 @@ static constexpr Array<@type@, @size@> @name@ { {)~~~");
             auto mapping = mapping_getter(value);
 
             generator.append(first ? " "sv : ", "sv);
-            generator.append(DeprecatedString::number(mapping));
+            generator.append(ByteString::number(mapping));
             first = false;
         }
 
@@ -2008,7 +2008,7 @@ static constexpr Array<@type@, @size@> @name@ { {)~~~");
     generator.append("\n");
 
     auto append_from_string = [&](StringView enum_title, StringView enum_snake, auto const& values, Vector<Alias> const& aliases = {}) -> ErrorOr<void> {
-        HashValueMap<DeprecatedString> hashes;
+        HashValueMap<ByteString> hashes;
         TRY(hashes.try_ensure_capacity(values.size()));
 
         for (auto const& value : values)
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateLocaleData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateLocaleData.cpp
index 383d068b79a..426816e8440 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateLocaleData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateLocaleData.cpp
@@ -6,8 +6,8 @@
 
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
 #include <AK/AllOf.h>
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Error.h>
 #include <AK/Format.h>
 #include <AK/HashMap.h>
@@ -22,14 +22,14 @@
 #include <LibCore/Directory.h>
 #include <LibFileSystem/FileSystem.h>
 
-static DeprecatedString format_identifier(StringView owner, DeprecatedString identifier)
+static ByteString format_identifier(StringView owner, ByteString identifier)
 {
     identifier = identifier.replace("-"sv, "_"sv, ReplaceMode::All);
 
     if (all_of(identifier, is_ascii_digit))
-        return DeprecatedString::formatted("{}_{}", owner[0], identifier);
+        return ByteString::formatted("{}_{}", owner[0], identifier);
     if (is_ascii_lower_alpha(identifier[0]))
-        return DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
+        return ByteString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
     return identifier;
 }
 
@@ -153,9 +153,9 @@ using KeywordList = Vector<size_t>;
 using ListPatternList = Vector<size_t>;
 
 struct LocaleData {
-    DeprecatedString language;
-    Optional<DeprecatedString> territory;
-    Optional<DeprecatedString> variant;
+    ByteString language;
+    Optional<ByteString> territory;
+    Optional<ByteString> variant;
     size_t display_patterns { 0 };
     size_t languages { 0 };
     size_t territories { 0 };
@@ -195,25 +195,25 @@ struct CLDR {
     UniqueStorage<ListPatternList> unique_list_pattern_lists;
     UniqueStorage<TextLayout> unique_text_layouts;
 
-    HashMap<DeprecatedString, LocaleData> locales;
+    HashMap<ByteString, LocaleData> locales;
     Vector<Alias> locale_aliases;
 
-    Vector<DeprecatedString> languages;
+    Vector<ByteString> languages;
     HashMap<StringView, size_t> language_indices;
 
-    Vector<DeprecatedString> territories;
+    Vector<ByteString> territories;
     HashMap<StringView, size_t> territory_indices;
 
-    Vector<DeprecatedString> scripts;
+    Vector<ByteString> scripts;
     HashMap<StringView, size_t> script_indices;
 
-    Vector<DeprecatedString> variants;
+    Vector<ByteString> variants;
     HashMap<StringView, size_t> variant_indices;
 
-    Vector<DeprecatedString> currencies;
+    Vector<ByteString> currencies;
     HashMap<StringView, size_t> currency_indices;
 
-    Vector<DeprecatedString> date_fields;
+    Vector<ByteString> date_fields;
     HashMap<StringView, size_t> date_fields_indices;
 
     Vector<Alias> date_field_aliases {
@@ -224,17 +224,17 @@ struct CLDR {
         { "zone"sv, "timeZoneName"sv },
     };
 
-    HashMap<DeprecatedString, Vector<DeprecatedString>> keywords;
-    HashMap<DeprecatedString, Vector<Alias>> keyword_aliases;
-    HashMap<DeprecatedString, DeprecatedString> keyword_names;
+    HashMap<ByteString, Vector<ByteString>> keywords;
+    HashMap<ByteString, Vector<Alias>> keyword_aliases;
+    HashMap<ByteString, ByteString> keyword_names;
 
-    Vector<DeprecatedString> list_pattern_types;
-    Vector<DeprecatedString> character_orders;
-    HashMap<DeprecatedString, size_t> language_aliases;
-    HashMap<DeprecatedString, size_t> territory_aliases;
-    HashMap<DeprecatedString, size_t> script_aliases;
-    HashMap<DeprecatedString, size_t> variant_aliases;
-    HashMap<DeprecatedString, size_t> subdivision_aliases;
+    Vector<ByteString> list_pattern_types;
+    Vector<ByteString> character_orders;
+    HashMap<ByteString, size_t> language_aliases;
+    HashMap<ByteString, size_t> territory_aliases;
+    HashMap<ByteString, size_t> script_aliases;
+    HashMap<ByteString, size_t> variant_aliases;
+    HashMap<ByteString, size_t> subdivision_aliases;
     Vector<LanguageMapping> complex_mappings;
     Vector<LanguageMapping> likely_subtags;
     size_t max_variant_size { 0 };
@@ -253,9 +253,9 @@ struct CLDR {
     })
 
 // NOTE: We return a pointer only because ErrorOr cannot store references. You may safely assume the pointer is non-null.
-ErrorOr<JsonValue const*> read_json_file_with_cache(DeprecatedString const& path)
+ErrorOr<JsonValue const*> read_json_file_with_cache(ByteString const& path)
 {
-    static HashMap<DeprecatedString, JsonValue> parsed_json_cache;
+    static HashMap<ByteString, JsonValue> parsed_json_cache;
 
     if (auto parsed_json = parsed_json_cache.get(path); parsed_json.has_value())
         return &parsed_json.value();
@@ -273,7 +273,7 @@ static ErrorOr<LanguageMapping> parse_language_mapping(CLDR& cldr, StringView ke
     return LanguageMapping { move(parsed_key), move(parsed_alias) };
 }
 
-static ErrorOr<void> parse_core_aliases(DeprecatedString core_supplemental_path, CLDR& cldr)
+static ErrorOr<void> parse_core_aliases(ByteString core_supplemental_path, CLDR& cldr)
 {
     LexicalPath core_aliases_path(move(core_supplemental_path));
     core_aliases_path = core_aliases_path.append("aliases.json"sv);
@@ -285,7 +285,7 @@ static ErrorOr<void> parse_core_aliases(DeprecatedString core_supplemental_path,
 
     auto append_aliases = [&](auto& alias_object, auto& alias_map) {
         alias_object.for_each_member([&](auto const& key, JsonValue const& value) {
-            auto alias = value.as_object().get_deprecated_string("_replacement"sv).value();
+            auto alias = value.as_object().get_byte_string("_replacement"sv).value();
 
             if (key.contains('-')) {
                 auto mapping = TRY_OR_DISCARD(parse_language_mapping(cldr, key, alias));
@@ -307,7 +307,7 @@ static ErrorOr<void> parse_core_aliases(DeprecatedString core_supplemental_path,
     return {};
 }
 
-static ErrorOr<void> parse_likely_subtags(DeprecatedString core_supplemental_path, CLDR& cldr)
+static ErrorOr<void> parse_likely_subtags(ByteString core_supplemental_path, CLDR& cldr)
 {
     LexicalPath likely_subtags_path(move(core_supplemental_path));
     likely_subtags_path = likely_subtags_path.append("likelySubtags.json"sv);
@@ -326,7 +326,7 @@ static ErrorOr<void> parse_likely_subtags(DeprecatedString core_supplemental_pat
     return {};
 }
 
-static ErrorOr<void> parse_identity(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_identity(ByteString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath locale_display_names_path(move(locale_path)); // Note: Every JSON file defines identity data, so we can use any of them.
     locale_display_names_path = locale_display_names_path.append("localeDisplayNames.json"sv);
@@ -335,10 +335,10 @@ static ErrorOr<void> parse_identity(DeprecatedString locale_path, CLDR& cldr, Lo
     auto const& main_object = locale_display_names.as_object().get_object("main"sv).value();
     auto const& locale_object = main_object.get_object(locale_display_names_path.parent().basename()).value();
     auto const& identity_object = locale_object.get_object("identity"sv).value();
-    auto const& language_string = identity_object.get_deprecated_string("language"sv).value();
-    auto const& territory_string = identity_object.get_deprecated_string("territory"sv);
-    auto const& script_string = identity_object.get_deprecated_string("script"sv);
-    auto const& variant_string = identity_object.get_deprecated_string("variant"sv);
+    auto const& language_string = identity_object.get_byte_string("language"sv).value();
+    auto const& territory_string = identity_object.get_byte_string("territory"sv);
+    auto const& script_string = identity_object.get_byte_string("script"sv);
+    auto const& variant_string = identity_object.get_byte_string("variant"sv);
 
     locale.language = language_string;
 
@@ -372,7 +372,7 @@ static ErrorOr<void> parse_identity(DeprecatedString locale_path, CLDR& cldr, Lo
     return {};
 }
 
-static ErrorOr<void> parse_locale_display_patterns(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_display_patterns(ByteString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath locale_display_names_path(move(locale_path));
     locale_display_names_path = locale_display_names_path.append("localeDisplayNames.json"sv);
@@ -382,8 +382,8 @@ static ErrorOr<void> parse_locale_display_patterns(DeprecatedString locale_path,
     auto const& locale_object = main_object.get_object(locale_display_names_path.parent().basename()).value();
     auto const& locale_display_names_object = locale_object.get_object("localeDisplayNames"sv).value();
     auto const& locale_display_patterns_object = locale_display_names_object.get_object("localeDisplayPattern"sv).value();
-    auto const& locale_pattern = locale_display_patterns_object.get_deprecated_string("localePattern"sv).value();
-    auto const& locale_separator = locale_display_patterns_object.get_deprecated_string("localeSeparator"sv).value();
+    auto const& locale_pattern = locale_display_patterns_object.get_byte_string("localePattern"sv).value();
+    auto const& locale_separator = locale_display_patterns_object.get_byte_string("localeSeparator"sv).value();
 
     DisplayPattern patterns {};
     patterns.locale_pattern = cldr.unique_strings.ensure(locale_pattern);
@@ -393,7 +393,7 @@ static ErrorOr<void> parse_locale_display_patterns(DeprecatedString locale_path,
     return {};
 }
 
-static ErrorOr<void> preprocess_languages(DeprecatedString locale_path, CLDR& cldr)
+static ErrorOr<void> preprocess_languages(ByteString locale_path, CLDR& cldr)
 {
     LexicalPath languages_path(move(locale_path));
     languages_path = languages_path.append("languages.json"sv);
@@ -417,7 +417,7 @@ static ErrorOr<void> preprocess_languages(DeprecatedString locale_path, CLDR& cl
     return {};
 }
 
-static ErrorOr<void> preprocess_currencies(DeprecatedString numbers_path, CLDR& cldr)
+static ErrorOr<void> preprocess_currencies(ByteString numbers_path, CLDR& cldr)
 {
     LexicalPath currencies_path(move(numbers_path));
     currencies_path = currencies_path.append("currencies.json"sv);
@@ -445,7 +445,7 @@ static bool is_sanctioned_date_field(StringView field)
     return field.is_one_of("era"sv, "year"sv, "quarter"sv, "month"sv, "week"sv, "weekday"sv, "day"sv, "dayperiod"sv, "hour"sv, "minute"sv, "second"sv, "zone"sv);
 }
 
-static ErrorOr<void> preprocess_date_fields(DeprecatedString dates_path, CLDR& cldr)
+static ErrorOr<void> preprocess_date_fields(ByteString dates_path, CLDR& cldr)
 {
     LexicalPath date_fields_path(move(dates_path));
     date_fields_path = date_fields_path.append("dateFields.json"sv);
@@ -469,7 +469,7 @@ static ErrorOr<void> preprocess_date_fields(DeprecatedString dates_path, CLDR& c
     return {};
 }
 
-static ErrorOr<void> parse_unicode_extension_keywords(DeprecatedString bcp47_path, CLDR& cldr)
+static ErrorOr<void> parse_unicode_extension_keywords(ByteString bcp47_path, CLDR& cldr)
 {
     constexpr auto desired_keywords = Array { "ca"sv, "co"sv, "hc"sv, "kf"sv, "kn"sv, "nu"sv };
     auto keywords = TRY(read_json_file(bcp47_path));
@@ -483,7 +483,7 @@ static ErrorOr<void> parse_unicode_extension_keywords(DeprecatedString bcp47_pat
         if (!desired_keywords.span().contains_slow(key))
             return;
 
-        auto const& name = value.as_object().get_deprecated_string("_alias"sv).value();
+        auto const& name = value.as_object().get_byte_string("_alias"sv).value();
         cldr.keyword_names.set(key, name);
 
         auto& keywords = cldr.keywords.ensure(key);
@@ -505,12 +505,12 @@ static ErrorOr<void> parse_unicode_extension_keywords(DeprecatedString bcp47_pat
             if (key == "nu"sv && keyword.is_one_of("finance"sv, "native"sv, "traditio"sv))
                 return;
 
-            if (auto const& preferred = properties.as_object().get_deprecated_string("_preferred"sv); preferred.has_value()) {
+            if (auto const& preferred = properties.as_object().get_byte_string("_preferred"sv); preferred.has_value()) {
                 cldr.keyword_aliases.ensure(key).append({ preferred.value(), keyword });
                 return;
             }
 
-            if (auto const& alias = properties.as_object().get_deprecated_string("_alias"sv); alias.has_value())
+            if (auto const& alias = properties.as_object().get_byte_string("_alias"sv); alias.has_value())
                 cldr.keyword_aliases.ensure(key).append({ keyword, alias.value() });
 
             keywords.append(keyword);
@@ -520,7 +520,7 @@ static ErrorOr<void> parse_unicode_extension_keywords(DeprecatedString bcp47_pat
     return {};
 }
 
-static Optional<DeprecatedString> find_keyword_alias(StringView key, StringView calendar, CLDR& cldr)
+static Optional<ByteString> find_keyword_alias(StringView key, StringView calendar, CLDR& cldr)
 {
     auto it = cldr.keyword_aliases.find(key);
     if (it == cldr.keyword_aliases.end())
@@ -533,7 +533,7 @@ static Optional<DeprecatedString> find_keyword_alias(StringView key, StringView
     return alias->name;
 }
 
-static ErrorOr<void> parse_locale_languages(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_languages(ByteString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath languages_path(move(locale_path));
     languages_path = languages_path.append("languages.json"sv);
@@ -567,7 +567,7 @@ static ErrorOr<void> parse_locale_languages(DeprecatedString locale_path, CLDR&
     return {};
 }
 
-static ErrorOr<void> parse_locale_territories(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_territories(ByteString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath territories_path(move(locale_path));
     territories_path = territories_path.append("territories.json"sv);
@@ -598,7 +598,7 @@ static ErrorOr<void> parse_locale_territories(DeprecatedString locale_path, CLDR
     return {};
 }
 
-static ErrorOr<void> parse_locale_scripts(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_scripts(ByteString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath scripts_path(move(locale_path));
     scripts_path = scripts_path.append("scripts.json"sv);
@@ -629,7 +629,7 @@ static ErrorOr<void> parse_locale_scripts(DeprecatedString locale_path, CLDR& cl
     return {};
 }
 
-static ErrorOr<void> parse_locale_list_patterns(DeprecatedString misc_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_list_patterns(ByteString misc_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath list_patterns_path(move(misc_path));
     list_patterns_path = list_patterns_path.append("listPatterns.json"sv);
@@ -664,10 +664,10 @@ static ErrorOr<void> parse_locale_list_patterns(DeprecatedString misc_path, CLDR
         auto type = list_pattern_type(key);
         auto style = list_pattern_style(key);
 
-        auto start = cldr.unique_strings.ensure(value.as_object().get_deprecated_string("start"sv).value());
-        auto middle = cldr.unique_strings.ensure(value.as_object().get_deprecated_string("middle"sv).value());
-        auto end = cldr.unique_strings.ensure(value.as_object().get_deprecated_string("end"sv).value());
-        auto pair = cldr.unique_strings.ensure(value.as_object().get_deprecated_string("2"sv).value());
+        auto start = cldr.unique_strings.ensure(value.as_object().get_byte_string("start"sv).value());
+        auto middle = cldr.unique_strings.ensure(value.as_object().get_byte_string("middle"sv).value());
+        auto end = cldr.unique_strings.ensure(value.as_object().get_byte_string("end"sv).value());
+        auto pair = cldr.unique_strings.ensure(value.as_object().get_byte_string("2"sv).value());
 
         if (!cldr.list_pattern_types.contains_slow(type))
             cldr.list_pattern_types.append(type);
@@ -680,7 +680,7 @@ static ErrorOr<void> parse_locale_list_patterns(DeprecatedString misc_path, CLDR
     return {};
 }
 
-static ErrorOr<void> parse_locale_layout(DeprecatedString misc_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_layout(ByteString misc_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath layout_path(move(misc_path));
     layout_path = layout_path.append("layout.json"sv);
@@ -699,7 +699,7 @@ static ErrorOr<void> parse_locale_layout(DeprecatedString misc_path, CLDR& cldr,
         VERIFY_NOT_REACHED();
     };
 
-    auto character_order = orientation_object.get_deprecated_string("characterOrder"sv).value();
+    auto character_order = orientation_object.get_byte_string("characterOrder"sv).value();
 
     TextLayout layout {};
     layout.character_order = text_layout_character_order(character_order);
@@ -711,7 +711,7 @@ static ErrorOr<void> parse_locale_layout(DeprecatedString misc_path, CLDR& cldr,
     return {};
 }
 
-static ErrorOr<void> parse_locale_currencies(DeprecatedString numbers_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_currencies(ByteString numbers_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath currencies_path(move(numbers_path));
     currencies_path = currencies_path.append("currencies.json"sv);
@@ -735,10 +735,10 @@ static ErrorOr<void> parse_locale_currencies(DeprecatedString numbers_path, CLDR
     numeric_currencies.resize(cldr.currencies.size());
 
     currencies_object.for_each_member([&](auto const& key, JsonValue const& value) {
-        auto long_name = value.as_object().get_deprecated_string("displayName"sv).value_or(key);
-        auto short_name = value.as_object().get_deprecated_string("symbol"sv).value_or(key);
-        auto narrow_name = value.as_object().get_deprecated_string("symbol-alt-narrow"sv);
-        auto numeric_name = value.as_object().get_deprecated_string("displayName-count-other"sv);
+        auto long_name = value.as_object().get_byte_string("displayName"sv).value_or(key);
+        auto short_name = value.as_object().get_byte_string("symbol"sv).value_or(key);
+        auto narrow_name = value.as_object().get_byte_string("symbol-alt-narrow"sv);
+        auto numeric_name = value.as_object().get_byte_string("displayName-count-other"sv);
 
         auto index = cldr.currency_indices.get(key).value();
         long_currencies[index] = cldr.unique_strings.ensure(move(long_name));
@@ -754,7 +754,7 @@ static ErrorOr<void> parse_locale_currencies(DeprecatedString numbers_path, CLDR
     return {};
 }
 
-static ErrorOr<void> parse_locale_calendars(DeprecatedString locale_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_calendars(ByteString locale_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath locale_display_names_path(move(locale_path));
     locale_display_names_path = locale_display_names_path.append("localeDisplayNames.json"sv);
@@ -789,7 +789,7 @@ static ErrorOr<void> parse_locale_calendars(DeprecatedString locale_path, CLDR&
     return {};
 }
 
-static ErrorOr<void> parse_locale_date_fields(DeprecatedString dates_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_locale_date_fields(ByteString dates_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath date_fields_path(move(dates_path));
     date_fields_path = date_fields_path.append("dateFields.json"sv);
@@ -813,9 +813,9 @@ static ErrorOr<void> parse_locale_date_fields(DeprecatedString dates_path, CLDR&
         if (!is_sanctioned_date_field(key))
             return;
 
-        auto const& long_name = value.as_object().get_deprecated_string("displayName"sv).value();
-        auto const& short_name = fields_object.get_object(DeprecatedString::formatted("{}-short", key))->get_deprecated_string("displayName"sv).value();
-        auto const& narrow_name = fields_object.get_object(DeprecatedString::formatted("{}-narrow", key))->get_deprecated_string("displayName"sv).value();
+        auto const& long_name = value.as_object().get_byte_string("displayName"sv).value();
+        auto const& short_name = fields_object.get_object(ByteString::formatted("{}-short", key))->get_byte_string("displayName"sv).value();
+        auto const& narrow_name = fields_object.get_object(ByteString::formatted("{}-narrow", key))->get_byte_string("displayName"sv).value();
 
         auto index = cldr.date_fields_indices.get(key).value();
         long_date_fields[index] = cldr.unique_strings.ensure(long_name);
@@ -829,7 +829,7 @@ static ErrorOr<void> parse_locale_date_fields(DeprecatedString dates_path, CLDR&
     return {};
 }
 
-static ErrorOr<void> parse_number_system_keywords(DeprecatedString locale_numbers_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_number_system_keywords(ByteString locale_numbers_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath numbers_path(move(locale_numbers_path));
     numbers_path = numbers_path.append("numbers.json"sv);
@@ -838,12 +838,12 @@ static ErrorOr<void> parse_number_system_keywords(DeprecatedString locale_number
     auto const& main_object = numbers.as_object().get_object("main"sv).value();
     auto const& locale_object = main_object.get_object(numbers_path.parent().basename()).value();
     auto const& locale_numbers_object = locale_object.get_object("numbers"sv).value();
-    auto const& default_numbering_system_object = locale_numbers_object.get_deprecated_string("defaultNumberingSystem"sv).value();
+    auto const& default_numbering_system_object = locale_numbers_object.get_byte_string("defaultNumberingSystem"sv).value();
     auto const& other_numbering_systems_object = locale_numbers_object.get_object("otherNumberingSystems"sv).value();
 
     KeywordList keywords {};
 
-    auto append_numbering_system = [&](DeprecatedString system_name) {
+    auto append_numbering_system = [&](ByteString system_name) {
         if (auto system_alias = find_keyword_alias("nu"sv, system_name, cldr); system_alias.has_value())
             system_name = system_alias.release_value();
 
@@ -868,7 +868,7 @@ static ErrorOr<void> parse_number_system_keywords(DeprecatedString locale_number
     return {};
 }
 
-static ErrorOr<void> parse_calendar_keywords(DeprecatedString locale_dates_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_calendar_keywords(ByteString locale_dates_path, CLDR& cldr, LocaleData& locale)
 {
     KeywordList keywords {};
 
@@ -934,7 +934,7 @@ static void fill_in_collation_keywords(CLDR& cldr, LocaleData& locale)
     locale.collation_numeric_keywords = kn_index;
 }
 
-static ErrorOr<void> parse_default_content_locales(DeprecatedString core_path, CLDR& cldr)
+static ErrorOr<void> parse_default_content_locales(ByteString core_path, CLDR& cldr)
 {
     LexicalPath default_content_path(move(core_path));
     default_content_path = default_content_path.append("defaultContent.json"sv);
@@ -983,7 +983,7 @@ static ErrorOr<void> define_aliases_without_scripts(CLDR& cldr)
         if ((parsed_locale.language == 0) || (parsed_locale.script == 0) || (parsed_locale.region == 0))
             return {};
 
-        auto locale_without_script = DeprecatedString::formatted("{}-{}",
+        auto locale_without_script = ByteString::formatted("{}-{}",
             cldr.unique_strings.get(parsed_locale.language),
             cldr.unique_strings.get(parsed_locale.region));
 
@@ -1008,7 +1008,7 @@ static ErrorOr<void> define_aliases_without_scripts(CLDR& cldr)
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(DeprecatedString bcp47_path, DeprecatedString core_path, DeprecatedString locale_names_path, DeprecatedString misc_path, DeprecatedString numbers_path, DeprecatedString dates_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(ByteString bcp47_path, ByteString core_path, ByteString locale_names_path, ByteString misc_path, ByteString numbers_path, ByteString dates_path, CLDR& cldr)
 {
     LexicalPath core_supplemental_path(core_path);
     core_supplemental_path = core_supplemental_path.append("supplemental"sv);
@@ -1017,7 +1017,7 @@ static ErrorOr<void> parse_all_locales(DeprecatedString bcp47_path, DeprecatedSt
     TRY(parse_core_aliases(core_supplemental_path.string(), cldr));
     TRY(parse_likely_subtags(core_supplemental_path.string(), cldr));
 
-    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
+    auto remove_variants_from_path = [&](ByteString path) -> ErrorOr<ByteString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -1027,7 +1027,7 @@ static ErrorOr<void> parse_all_locales(DeprecatedString bcp47_path, DeprecatedSt
         if (auto region = cldr.unique_strings.get(parsed_locale.region); !region.is_empty())
             builder.appendff("-{}", region);
 
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
 
     TRY(Core::Directory::for_each_entry(TRY(String::formatted("{}/main", locale_names_path)), Core::DirIterator::SkipParentAndBaseDir, [&](auto& entry, auto& directory) -> ErrorOr<IterationDecision> {
@@ -1156,7 +1156,7 @@ namespace Locale {
 
     for (auto& keyword : cldr.keywords) {
         auto const& keyword_name = cldr.keyword_names.find(keyword.key)->value;
-        auto enum_name = DeprecatedString::formatted("Keyword{}", format_identifier({}, keyword_name));
+        auto enum_name = ByteString::formatted("Keyword{}", format_identifier({}, keyword_name));
 
         if (auto aliases = cldr.keyword_aliases.find(keyword.key); aliases != cldr.keyword_aliases.end())
             generate_enum(generator, format_identifier, enum_name, {}, keyword.value, aliases->value);
@@ -1179,9 +1179,9 @@ static ErrorOr<void> generate_unicode_locale_implementation(Core::InputBufferedF
     StringBuilder builder;
     SourceGenerator generator { builder };
     generator.set("string_index_type"sv, string_index_type);
-    generator.set("locales_size"sv, DeprecatedString::number(cldr.locales.size()));
-    generator.set("territories_size", DeprecatedString::number(cldr.territories.size()));
-    generator.set("variants_size", DeprecatedString::number(cldr.max_variant_size));
+    generator.set("locales_size"sv, ByteString::number(cldr.locales.size()));
+    generator.set("territories_size", ByteString::number(cldr.territories.size()));
+    generator.set("variants_size", ByteString::number(cldr.max_variant_size));
 
     generator.append(R"~~~(
 #include <AK/Array.h>
@@ -1285,7 +1285,7 @@ ReadonlySpan<StringView> get_available_keyword_values(StringView key)
     cldr.unique_text_layouts.generate(generator, "TextLayout"sv, "s_text_layouts"sv, 30);
 
     auto append_index = [&](auto index) {
-        generator.append(DeprecatedString::formatted(", {}", index));
+        generator.append(ByteString::formatted(", {}", index));
     };
 
     auto append_list_and_size = [&](auto const& list) {
@@ -1298,16 +1298,16 @@ ReadonlySpan<StringView> get_available_keyword_values(StringView key)
         generator.append(", {");
         for (auto const& item : list) {
             generator.append(first ? " "sv : ", "sv);
-            generator.append(DeprecatedString::number(item));
+            generator.append(ByteString::number(item));
             first = false;
         }
-        generator.append(DeprecatedString::formatted(" }}, {}", list.size()));
+        generator.append(ByteString::formatted(" }}, {}", list.size()));
     };
 
     auto append_mapping = [&](auto const& keys, auto const& map, auto type, auto name, auto mapping_getter) {
         generator.set("type", type);
         generator.set("name", name);
-        generator.set("size", DeprecatedString::number(keys.size()));
+        generator.set("size", ByteString::number(keys.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {)~~~");
@@ -1318,7 +1318,7 @@ static constexpr Array<@type@, @size@> @name@ { {)~~~");
             auto mapping = mapping_getter(value);
 
             generator.append(first ? " "sv : ", "sv);
-            generator.append(DeprecatedString::number(mapping));
+            generator.append(ByteString::number(mapping));
             first = false;
         }
 
@@ -1396,7 +1396,7 @@ struct LanguageMapping {
 )~~~");
 
     auto append_complex_mapping = [&](StringView name, auto& mappings) {
-        generator.set("size", DeprecatedString::number(mappings.size()));
+        generator.set("size", ByteString::number(mappings.size()));
         generator.set("name"sv, name);
 
         generator.append(R"~~~(
@@ -1416,14 +1416,14 @@ static constexpr Array<LanguageMapping, @size@> s_@name@ { {
         });
 
         for (auto const& mapping : mappings) {
-            generator.set("language"sv, DeprecatedString::number(mapping.key.language));
+            generator.set("language"sv, ByteString::number(mapping.key.language));
             generator.append("    { { @language@");
 
             append_index(mapping.key.script);
             append_index(mapping.key.region);
             append_list_and_size(mapping.key.variants);
 
-            generator.set("language"sv, DeprecatedString::number(mapping.alias.language));
+            generator.set("language"sv, ByteString::number(mapping.alias.language));
             generator.append(" }, { @language@");
 
             append_index(mapping.alias.script);
@@ -1563,7 +1563,7 @@ Optional<StringView> get_locale_@enum_snake@_mapping(StringView locale, StringVi
     };
 
     auto append_from_string = [&](StringView enum_title, StringView enum_snake, auto const& values, Vector<Alias> const& aliases = {}) -> ErrorOr<void> {
-        HashValueMap<DeprecatedString> hashes;
+        HashValueMap<ByteString> hashes;
         TRY(hashes.try_ensure_capacity(values.size()));
 
         for (auto const& value : values)
@@ -1621,8 +1621,8 @@ Optional<StringView> get_locale_@enum_snake@_mapping(StringView locale, StringVi
 
     for (auto const& keyword : cldr.keywords) {
         auto const& keyword_name = cldr.keyword_names.find(keyword.key)->value;
-        auto enum_name = DeprecatedString::formatted("Keyword{}", format_identifier({}, keyword_name));
-        auto enum_snake = DeprecatedString::formatted("keyword_{}", keyword.key);
+        auto enum_name = ByteString::formatted("Keyword{}", format_identifier({}, keyword_name));
+        auto enum_snake = ByteString::formatted("keyword_{}", keyword.key);
 
         if (auto aliases = cldr.keyword_aliases.find(keyword.key); aliases != cldr.keyword_aliases.end())
             TRY(append_from_string(enum_name, enum_snake, keyword.value, aliases->value));
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateNumberFormatData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateNumberFormatData.cpp
index 1059270ad93..646bff5926c 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateNumberFormatData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateNumberFormatData.cpp
@@ -7,8 +7,8 @@
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
 #include <AK/AllOf.h>
 #include <AK/Array.h>
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Find.h>
 #include <AK/Format.h>
 #include <AK/HashFunctions.h>
@@ -85,7 +85,7 @@ struct AK::Formatter<NumberFormat> : Formatter<FormatString> {
             format.zero_format_index,
             format.positive_format_index,
             format.negative_format_index,
-            identifier_indices.to_deprecated_string());
+            identifier_indices.to_byte_string());
     }
 };
 
@@ -215,7 +215,7 @@ struct AK::Traits<Unit> : public DefaultTraits<Unit> {
 
 struct LocaleData {
     Vector<size_t> number_systems;
-    HashMap<DeprecatedString, size_t> units {};
+    HashMap<ByteString, size_t> units {};
     u8 minimum_grouping_digits { 0 };
 };
 
@@ -227,14 +227,14 @@ struct CLDR {
     UniqueStorage<NumberSystem> unique_systems;
     UniqueStorage<Unit> unique_units;
 
-    HashMap<DeprecatedString, Array<u32, 10>> number_system_digits;
-    Vector<DeprecatedString> number_systems;
+    HashMap<ByteString, Array<u32, 10>> number_system_digits;
+    Vector<ByteString> number_systems;
 
-    HashMap<DeprecatedString, LocaleData> locales;
+    HashMap<ByteString, LocaleData> locales;
     size_t max_identifier_count { 0 };
 };
 
-static ErrorOr<void> parse_number_system_digits(DeprecatedString core_supplemental_path, CLDR& cldr)
+static ErrorOr<void> parse_number_system_digits(ByteString core_supplemental_path, CLDR& cldr)
 {
     LexicalPath number_systems_path(move(core_supplemental_path));
     number_systems_path = number_systems_path.append("numberingSystems.json"sv);
@@ -244,11 +244,11 @@ static ErrorOr<void> parse_number_system_digits(DeprecatedString core_supplement
     auto const& number_systems_object = supplemental_object.get_object("numberingSystems"sv).value();
 
     number_systems_object.for_each_member([&](auto const& number_system, auto const& digits_object) {
-        auto type = digits_object.as_object().get_deprecated_string("_type"sv).value();
+        auto type = digits_object.as_object().get_byte_string("_type"sv).value();
         if (type != "numeric"sv)
             return;
 
-        auto digits = digits_object.as_object().get_deprecated_string("_digits"sv).value();
+        auto digits = digits_object.as_object().get_byte_string("_digits"sv).value();
 
         Utf8View utf8_digits { digits };
         VERIFY(utf8_digits.length() == 10);
@@ -266,7 +266,7 @@ static ErrorOr<void> parse_number_system_digits(DeprecatedString core_supplement
     return {};
 }
 
-static DeprecatedString parse_identifiers(DeprecatedString pattern, StringView replacement, CLDR& cldr, NumberFormat& format)
+static ByteString parse_identifiers(ByteString pattern, StringView replacement, CLDR& cldr, NumberFormat& format)
 {
     static constexpr Utf8View whitespace { "\u0020\u00a0\u200f"sv };
 
@@ -312,7 +312,7 @@ static DeprecatedString parse_identifiers(DeprecatedString pattern, StringView r
             cldr.max_identifier_count = max(cldr.max_identifier_count, format.identifier_indices.size());
         }
 
-        pattern = DeprecatedString::formatted("{}{{{}:{}}}{}",
+        pattern = ByteString::formatted("{}{{{}:{}}}{}",
             *start_index > 0 ? pattern.substring_view(0, *start_index) : ""sv,
             replacement,
             replacement_index,
@@ -320,13 +320,13 @@ static DeprecatedString parse_identifiers(DeprecatedString pattern, StringView r
     }
 }
 
-static void parse_number_pattern(Vector<DeprecatedString> patterns, CLDR& cldr, NumberFormatType type, NumberFormat& format, NumberSystem* number_system_for_groupings = nullptr)
+static void parse_number_pattern(Vector<ByteString> patterns, CLDR& cldr, NumberFormatType type, NumberFormat& format, NumberSystem* number_system_for_groupings = nullptr)
 {
     // https://unicode.org/reports/tr35/tr35-numbers.html#Number_Format_Patterns
     // https://cldr.unicode.org/translation/number-currency-formats/number-and-currency-patterns
     VERIFY((patterns.size() == 1) || (patterns.size() == 2));
 
-    auto replace_patterns = [&](DeprecatedString pattern) {
+    auto replace_patterns = [&](ByteString pattern) {
         static HashMap<StringView, StringView> replacements = {
             { "{0}"sv, "{number}"sv },
             { "{1}"sv, "{currency}"sv },
@@ -340,7 +340,7 @@ static void parse_number_pattern(Vector<DeprecatedString> patterns, CLDR& cldr,
         for (auto const& replacement : replacements)
             pattern = pattern.replace(replacement.key, replacement.value, ReplaceMode::All);
 
-        if (auto start_number_index = pattern.find_any_of("#0"sv, DeprecatedString::SearchDirection::Forward); start_number_index.has_value()) {
+        if (auto start_number_index = pattern.find_any_of("#0"sv, ByteString::SearchDirection::Forward); start_number_index.has_value()) {
             auto end_number_index = *start_number_index + 1;
 
             for (; end_number_index < pattern.length(); ++end_number_index) {
@@ -367,7 +367,7 @@ static void parse_number_pattern(Vector<DeprecatedString> patterns, CLDR& cldr,
                 }
             }
 
-            pattern = DeprecatedString::formatted("{}{{number}}{}",
+            pattern = ByteString::formatted("{}{{number}}{}",
                 *start_number_index > 0 ? pattern.substring_view(0, *start_number_index) : ""sv,
                 pattern.substring_view(end_number_index));
 
@@ -384,19 +384,19 @@ static void parse_number_pattern(Vector<DeprecatedString> patterns, CLDR& cldr,
     };
 
     auto zero_format = replace_patterns(move(patterns[0]));
-    format.positive_format_index = cldr.unique_strings.ensure(DeprecatedString::formatted("{{plusSign}}{}", zero_format));
+    format.positive_format_index = cldr.unique_strings.ensure(ByteString::formatted("{{plusSign}}{}", zero_format));
 
     if (patterns.size() == 2) {
         auto negative_format = replace_patterns(move(patterns[1]));
         format.negative_format_index = cldr.unique_strings.ensure(move(negative_format));
     } else {
-        format.negative_format_index = cldr.unique_strings.ensure(DeprecatedString::formatted("{{minusSign}}{}", zero_format));
+        format.negative_format_index = cldr.unique_strings.ensure(ByteString::formatted("{{minusSign}}{}", zero_format));
     }
 
     format.zero_format_index = cldr.unique_strings.ensure(move(zero_format));
 }
 
-static void parse_number_pattern(Vector<DeprecatedString> patterns, CLDR& cldr, NumberFormatType type, size_t& format_index, NumberSystem* number_system_for_groupings = nullptr)
+static void parse_number_pattern(Vector<ByteString> patterns, CLDR& cldr, NumberFormatType type, size_t& format_index, NumberSystem* number_system_for_groupings = nullptr)
 {
     NumberFormat format {};
     parse_number_pattern(move(patterns), cldr, type, format, number_system_for_groupings);
@@ -404,7 +404,7 @@ static void parse_number_pattern(Vector<DeprecatedString> patterns, CLDR& cldr,
     format_index = cldr.unique_formats.ensure(move(format));
 }
 
-static ErrorOr<void> parse_number_systems(DeprecatedString locale_numbers_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_number_systems(ByteString locale_numbers_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath numbers_path(move(locale_numbers_path));
     numbers_path = numbers_path.append("numbers.json"sv);
@@ -413,7 +413,7 @@ static ErrorOr<void> parse_number_systems(DeprecatedString locale_numbers_path,
     auto const& main_object = numbers.as_object().get_object("main"sv).value();
     auto const& locale_object = main_object.get_object(numbers_path.parent().basename()).value();
     auto const& locale_numbers_object = locale_object.get_object("numbers"sv).value();
-    auto const& minimum_grouping_digits = locale_numbers_object.get_deprecated_string("minimumGroupingDigits"sv).value();
+    auto const& minimum_grouping_digits = locale_numbers_object.get_byte_string("minimumGroupingDigits"sv).value();
 
     Vector<Optional<NumberSystem>> number_systems;
     number_systems.resize(cldr.number_systems.size());
@@ -517,9 +517,9 @@ static ErrorOr<void> parse_number_systems(DeprecatedString locale_numbers_path,
 
             // The range separator does not appear in the symbols list, we have to extract it from
             // the range pattern.
-            auto misc_patterns_key = DeprecatedString::formatted("{}{}", misc_patterns_prefix, system);
+            auto misc_patterns_key = ByteString::formatted("{}{}", misc_patterns_prefix, system);
             auto misc_patterns = locale_numbers_object.get_object(misc_patterns_key).value();
-            auto range_separator = misc_patterns.get_deprecated_string("range"sv).value();
+            auto range_separator = misc_patterns.get_byte_string("range"sv).value();
 
             auto begin_index = range_separator.find("{0}"sv).value() + "{0}"sv.length();
             auto end_index = range_separator.find("{1}"sv).value();
@@ -536,7 +536,7 @@ static ErrorOr<void> parse_number_systems(DeprecatedString locale_numbers_path,
             auto system = key.substring(decimal_formats_prefix.length());
             auto& number_system = ensure_number_system(system);
 
-            auto format_object = value.as_object().get_deprecated_string("standard"sv).value();
+            auto format_object = value.as_object().get_byte_string("standard"sv).value();
             parse_number_pattern(format_object.split(';'), cldr, NumberFormatType::Standard, number_system.decimal_format, &number_system);
 
             auto const& long_format = value.as_object().get_object("long"sv)->get_object("decimalFormat"sv).value();
@@ -548,10 +548,10 @@ static ErrorOr<void> parse_number_systems(DeprecatedString locale_numbers_path,
             auto system = key.substring(currency_formats_prefix.length());
             auto& number_system = ensure_number_system(system);
 
-            auto format_object = value.as_object().get_deprecated_string("standard"sv).value();
+            auto format_object = value.as_object().get_byte_string("standard"sv).value();
             parse_number_pattern(format_object.split(';'), cldr, NumberFormatType::Standard, number_system.currency_format);
 
-            format_object = value.as_object().get_deprecated_string("accounting"sv).value();
+            format_object = value.as_object().get_byte_string("accounting"sv).value();
             parse_number_pattern(format_object.split(';'), cldr, NumberFormatType::Standard, number_system.accounting_format);
 
             number_system.currency_unit_formats = parse_number_format(value.as_object());
@@ -559,13 +559,13 @@ static ErrorOr<void> parse_number_systems(DeprecatedString locale_numbers_path,
             auto system = key.substring(percent_formats_prefix.length());
             auto& number_system = ensure_number_system(system);
 
-            auto format_object = value.as_object().get_deprecated_string("standard"sv).value();
+            auto format_object = value.as_object().get_byte_string("standard"sv).value();
             parse_number_pattern(format_object.split(';'), cldr, NumberFormatType::Standard, number_system.percent_format);
         } else if (key.starts_with(scientific_formats_prefix)) {
             auto system = key.substring(scientific_formats_prefix.length());
             auto& number_system = ensure_number_system(system);
 
-            auto format_object = value.as_object().get_deprecated_string("standard"sv).value();
+            auto format_object = value.as_object().get_byte_string("standard"sv).value();
             parse_number_pattern(format_object.split(';'), cldr, NumberFormatType::Standard, number_system.scientific_format);
         }
     });
@@ -584,7 +584,7 @@ static ErrorOr<void> parse_number_systems(DeprecatedString locale_numbers_path,
     return {};
 }
 
-static ErrorOr<void> parse_units(DeprecatedString locale_units_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_units(ByteString locale_units_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath units_path(move(locale_units_path));
     units_path = units_path.append("units.json"sv);
@@ -597,7 +597,7 @@ static ErrorOr<void> parse_units(DeprecatedString locale_units_path, CLDR& cldr,
     auto const& short_object = locale_units_object.get_object("short"sv).value();
     auto const& narrow_object = locale_units_object.get_object("narrow"sv).value();
 
-    HashMap<DeprecatedString, Unit> units;
+    HashMap<ByteString, Unit> units;
 
     auto ensure_unit = [&](auto const& unit) -> Unit& {
         return units.ensure(unit, [&]() {
@@ -687,7 +687,7 @@ static ErrorOr<void> parse_units(DeprecatedString locale_units_path, CLDR& cldr,
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedString numbers_path, DeprecatedString units_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(ByteString core_path, ByteString numbers_path, ByteString units_path, CLDR& cldr)
 {
     LexicalPath core_supplemental_path(move(core_path));
     core_supplemental_path = core_supplemental_path.append("supplemental"sv);
@@ -695,7 +695,7 @@ static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedStr
 
     TRY(parse_number_system_digits(core_supplemental_path.string(), cldr));
 
-    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
+    auto remove_variants_from_path = [&](ByteString path) -> ErrorOr<ByteString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -705,7 +705,7 @@ static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedStr
         if (auto region = cldr.unique_strings.get(parsed_locale.region); !region.is_empty())
             builder.appendff("-{}", region);
 
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
 
     TRY(Core::Directory::for_each_entry(TRY(String::formatted("{}/main", numbers_path)), Core::DirIterator::SkipParentAndBaseDir, [&](auto& entry, auto& directory) -> ErrorOr<IterationDecision> {
@@ -729,7 +729,7 @@ static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedStr
     return {};
 }
 
-static DeprecatedString format_identifier(StringView, DeprecatedString identifier)
+static ByteString format_identifier(StringView, ByteString identifier)
 {
     return identifier.to_titlecase();
 }
@@ -765,7 +765,7 @@ static ErrorOr<void> generate_unicode_locale_implementation(Core::InputBufferedF
     generator.set("number_format_index_type"sv, cldr.unique_formats.type_that_fits());
     generator.set("number_format_list_index_type"sv, cldr.unique_format_lists.type_that_fits());
     generator.set("numeric_symbol_list_index_type"sv, cldr.unique_symbols.type_that_fits());
-    generator.set("identifier_count", DeprecatedString::number(cldr.max_identifier_count));
+    generator.set("identifier_count", ByteString::number(cldr.max_identifier_count));
 
     generator.append(R"~~~(
 #include <AK/Array.h>
@@ -848,22 +848,22 @@ struct Unit {
     auto locales = cldr.locales.keys();
     quick_sort(locales);
 
-    generator.set("size", DeprecatedString::number(locales.size()));
+    generator.set("size", ByteString::number(locales.size()));
     generator.append(R"~~~(
 static constexpr Array<u8, @size@> s_minimum_grouping_digits { { )~~~");
 
     bool first = true;
     for (auto const& locale : locales) {
         generator.append(first ? " "sv : ", "sv);
-        generator.append(DeprecatedString::number(cldr.locales.find(locale)->value.minimum_grouping_digits));
+        generator.append(ByteString::number(cldr.locales.find(locale)->value.minimum_grouping_digits));
         first = false;
     }
     generator.append(" } };\n");
 
-    auto append_map = [&](DeprecatedString name, auto type, auto const& map) {
+    auto append_map = [&](ByteString name, auto type, auto const& map) {
         generator.set("name", name);
         generator.set("type", type);
-        generator.set("size", DeprecatedString::number(map.size()));
+        generator.set("size", ByteString::number(map.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {)~~~");
@@ -872,9 +872,9 @@ static constexpr Array<@type@, @size@> @name@ { {)~~~");
         for (auto const& item : map) {
             generator.append(first ? " "sv : ", "sv);
             if constexpr (requires { item.value; })
-                generator.append(DeprecatedString::number(item.value));
+                generator.append(ByteString::number(item.value));
             else
-                generator.append(DeprecatedString::number(item));
+                generator.append(ByteString::number(item));
             first = false;
         }
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GeneratePluralRulesData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GeneratePluralRulesData.cpp
index 42ae2f990a3..8cf12eb887c 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GeneratePluralRulesData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GeneratePluralRulesData.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonParser.h>
 #include <AK/JsonValue.h>
@@ -18,14 +18,14 @@
 #include <LibFileSystem/FileSystem.h>
 #include <LibLocale/PluralRules.h>
 
-static DeprecatedString format_identifier(StringView owner, DeprecatedString identifier)
+static ByteString format_identifier(StringView owner, ByteString identifier)
 {
     identifier = identifier.replace("-"sv, "_"sv, ReplaceMode::All);
 
     if (all_of(identifier, is_ascii_digit))
-        return DeprecatedString::formatted("{}_{}", owner[0], identifier);
+        return ByteString::formatted("{}_{}", owner[0], identifier);
     if (is_ascii_lower_alpha(identifier[0]))
-        return DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
+        return ByteString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
     return identifier;
 }
 
@@ -38,20 +38,20 @@ struct Relation {
         Inequality,
     };
 
-    DeprecatedString const& modulus_variable_name() const
+    ByteString const& modulus_variable_name() const
     {
         VERIFY(modulus.has_value());
 
         if (!cached_modulus_variable_name.has_value())
-            cached_modulus_variable_name = DeprecatedString::formatted("mod_{}_{}", symbol, *modulus);
+            cached_modulus_variable_name = ByteString::formatted("mod_{}_{}", symbol, *modulus);
 
         return *cached_modulus_variable_name;
     }
 
-    DeprecatedString const& exponential_variable_name() const
+    ByteString const& exponential_variable_name() const
     {
         if (!cached_exponential_variable_name.has_value())
-            cached_exponential_variable_name = DeprecatedString::formatted("exp_{}", symbol);
+            cached_exponential_variable_name = ByteString::formatted("exp_{}", symbol);
 
         return *cached_exponential_variable_name;
     }
@@ -64,25 +64,25 @@ struct Relation {
             else if (symbol == 'e' || symbol == 'c')
                 generator.append(exponential_variable_name());
             else
-                generator.append(DeprecatedString::formatted("ops.{}", Locale::PluralOperands::symbol_to_variable_name(symbol)));
+                generator.append(ByteString::formatted("ops.{}", Locale::PluralOperands::symbol_to_variable_name(symbol)));
         };
 
         auto append_value = [&](u32 value) {
             append_variable_name();
             generator.append(" == "sv);
-            generator.append(DeprecatedString::number(value));
+            generator.append(ByteString::number(value));
         };
 
         auto append_range = [&](auto const& range) {
             // This check avoids generating "0 <= unsigned_value", which is always true.
             if (range[0] != 0 || Locale::PluralOperands::symbol_requires_floating_point_modulus(symbol)) {
-                generator.append(DeprecatedString::formatted("{} <= ", range[0]));
+                generator.append(ByteString::formatted("{} <= ", range[0]));
                 append_variable_name();
                 generator.append(" && "sv);
             }
 
             append_variable_name();
-            generator.append(DeprecatedString::formatted(" <= {}", range[1]));
+            generator.append(ByteString::formatted(" <= {}", range[1]));
         };
 
         if (type == Type::Inequality)
@@ -105,7 +105,7 @@ struct Relation {
         generator.append(")"sv);
     }
 
-    void generate_precomputed_variables(SourceGenerator& generator, HashTable<DeprecatedString>& generated_variables) const
+    void generate_precomputed_variables(SourceGenerator& generator, HashTable<ByteString>& generated_variables) const
     {
         // FIXME: How do we handle the exponential symbols? They seem unused by ECMA-402.
         if (symbol == 'e' || symbol == 'c') {
@@ -127,7 +127,7 @@ struct Relation {
         generated_variables.set(variable);
         generator.set("variable"sv, move(variable));
         generator.set("operand"sv, Locale::PluralOperands::symbol_to_variable_name(symbol));
-        generator.set("modulus"sv, DeprecatedString::number(*modulus));
+        generator.set("modulus"sv, ByteString::number(*modulus));
 
         if (Locale::PluralOperands::symbol_requires_floating_point_modulus(symbol)) {
             generator.append(R"~~~(
@@ -144,8 +144,8 @@ struct Relation {
     Vector<Comparator> comparators;
 
 private:
-    mutable Optional<DeprecatedString> cached_modulus_variable_name;
-    mutable Optional<DeprecatedString> cached_exponential_variable_name;
+    mutable Optional<ByteString> cached_modulus_variable_name;
+    mutable Optional<ByteString> cached_exponential_variable_name;
 };
 
 struct Condition {
@@ -170,7 +170,7 @@ struct Condition {
         }
     }
 
-    void generate_precomputed_variables(SourceGenerator& generator, HashTable<DeprecatedString>& generated_variables) const
+    void generate_precomputed_variables(SourceGenerator& generator, HashTable<ByteString>& generated_variables) const
     {
         for (auto const& conjunctions : relations) {
             for (auto const& relation : conjunctions)
@@ -182,18 +182,18 @@ struct Condition {
 };
 
 struct Range {
-    DeprecatedString start;
-    DeprecatedString end;
-    DeprecatedString category;
+    ByteString start;
+    ByteString end;
+    ByteString category;
 };
 
-using Conditions = HashMap<DeprecatedString, Condition>;
+using Conditions = HashMap<ByteString, Condition>;
 using Ranges = Vector<Range>;
 
 struct LocaleData {
-    static DeprecatedString generated_method_name(StringView form, StringView locale)
+    static ByteString generated_method_name(StringView form, StringView locale)
     {
-        return DeprecatedString::formatted("{}_plurality_{}", form, format_identifier({}, locale));
+        return ByteString::formatted("{}_plurality_{}", form, format_identifier({}, locale));
     }
 
     Conditions& rules_for_form(StringView form)
@@ -213,7 +213,7 @@ struct LocaleData {
 struct CLDR {
     UniqueStringStorage unique_strings;
 
-    HashMap<DeprecatedString, LocaleData> locales;
+    HashMap<ByteString, LocaleData> locales;
 };
 
 static Relation parse_relation(StringView relation)
@@ -321,7 +321,7 @@ static void parse_condition(StringView category, StringView rule, Conditions& ru
     });
 }
 
-static ErrorOr<void> parse_plural_rules(DeprecatedString core_supplemental_path, StringView file_name, CLDR& cldr)
+static ErrorOr<void> parse_plural_rules(ByteString core_supplemental_path, StringView file_name, CLDR& cldr)
 {
     static constexpr auto form_prefix = "plurals-type-"sv;
     static constexpr auto rule_prefix = "pluralRule-count-"sv;
@@ -356,7 +356,7 @@ static ErrorOr<void> parse_plural_rules(DeprecatedString core_supplemental_path,
 }
 
 // https://unicode.org/reports/tr35/tr35-numbers.html#Plural_Ranges
-static ErrorOr<void> parse_plural_ranges(DeprecatedString core_supplemental_path, CLDR& cldr)
+static ErrorOr<void> parse_plural_ranges(ByteString core_supplemental_path, CLDR& cldr)
 {
     static constexpr auto start_segment = "-start-"sv;
     static constexpr auto end_segment = "-end-"sv;
@@ -392,13 +392,13 @@ static ErrorOr<void> parse_plural_ranges(DeprecatedString core_supplemental_path
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedString locale_names_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(ByteString core_path, ByteString locale_names_path, CLDR& cldr)
 {
     LexicalPath core_supplemental_path(move(core_path));
     core_supplemental_path = core_supplemental_path.append("supplemental"sv);
     VERIFY(FileSystem::is_directory(core_supplemental_path.string()));
 
-    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
+    auto remove_variants_from_path = [&](ByteString path) -> ErrorOr<ByteString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -408,7 +408,7 @@ static ErrorOr<void> parse_all_locales(DeprecatedString core_path, DeprecatedStr
         if (auto region = cldr.unique_strings.get(parsed_locale.region); !region.is_empty())
             builder.appendff("-{}", region);
 
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
 
     TRY(Core::Directory::for_each_entry(TRY(String::formatted("{}/main", locale_names_path)), Core::DirIterator::SkipParentAndBaseDir, [&](auto& entry, auto& directory) -> ErrorOr<IterationDecision> {
@@ -484,7 +484,7 @@ static PluralCategory default_range(PluralCategory, PluralCategory end)
             return;
 
         generator.set("method"sv, LocaleData::generated_method_name(form, locale));
-        HashTable<DeprecatedString> generated_variables;
+        HashTable<ByteString> generated_variables;
 
         generator.append(R"~~~(
 static PluralCategory @method@([[maybe_unused]] PluralOperands ops)
@@ -539,7 +539,7 @@ static PluralCategory @method@(PluralCategory start, PluralCategory end)
         generator.set("type"sv, type);
         generator.set("form"sv, form);
         generator.set("default"sv, default_);
-        generator.set("size"sv, DeprecatedString::number(locales.size()));
+        generator.set("size"sv, ByteString::number(locales.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> s_@form@_functions { {)~~~");
@@ -564,7 +564,7 @@ static constexpr Array<@type@, @size@> s_@form@_functions { {)~~~");
 
     auto append_categories = [&](auto const& name, auto const& rules) {
         generator.set("name", name);
-        generator.set("size", DeprecatedString::number(rules.size() + 1));
+        generator.set("size", ByteString::number(rules.size() + 1));
 
         generator.append(R"~~~(
 static constexpr Array<PluralCategory, @size@> @name@ { { PluralCategory::Other)~~~");
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateRelativeTimeFormatData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateRelativeTimeFormatData.cpp
index f68e69efc76..2fe54a6d201 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateRelativeTimeFormatData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibLocale/GenerateRelativeTimeFormatData.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/HashMap.h>
 #include <AK/JsonObject.h>
@@ -39,9 +39,9 @@ struct RelativeTimeFormat {
             && (pattern == other.pattern);
     }
 
-    DeprecatedString time_unit;
-    DeprecatedString style;
-    DeprecatedString plurality;
+    ByteString time_unit;
+    ByteString style;
+    ByteString plurality;
     size_t tense_or_number { 0 };
     size_t pattern { 0 };
 };
@@ -73,10 +73,10 @@ struct CLDR {
     UniqueStringStorage unique_strings;
     UniqueStorage<RelativeTimeFormat> unique_formats;
 
-    HashMap<DeprecatedString, LocaleData> locales;
+    HashMap<ByteString, LocaleData> locales;
 };
 
-static ErrorOr<void> parse_date_fields(DeprecatedString locale_dates_path, CLDR& cldr, LocaleData& locale)
+static ErrorOr<void> parse_date_fields(ByteString locale_dates_path, CLDR& cldr, LocaleData& locale)
 {
     LexicalPath date_fields_path(move(locale_dates_path));
     date_fields_path = date_fields_path.append("dateFields.json"sv);
@@ -135,9 +135,9 @@ static ErrorOr<void> parse_date_fields(DeprecatedString locale_dates_path, CLDR&
     return {};
 }
 
-static ErrorOr<void> parse_all_locales(DeprecatedString dates_path, CLDR& cldr)
+static ErrorOr<void> parse_all_locales(ByteString dates_path, CLDR& cldr)
 {
-    auto remove_variants_from_path = [&](DeprecatedString path) -> ErrorOr<DeprecatedString> {
+    auto remove_variants_from_path = [&](ByteString path) -> ErrorOr<ByteString> {
         auto parsed_locale = TRY(CanonicalLanguageID::parse(cldr.unique_strings, LexicalPath::basename(path)));
 
         StringBuilder builder;
@@ -147,7 +147,7 @@ static ErrorOr<void> parse_all_locales(DeprecatedString dates_path, CLDR& cldr)
         if (auto region = cldr.unique_strings.get(parsed_locale.region); !region.is_empty())
             builder.appendff("-{}", region);
 
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
 
     TRY(Core::Directory::for_each_entry(TRY(String::formatted("{}/main", dates_path)), Core::DirIterator::SkipParentAndBaseDir, [&](auto& entry, auto& directory) -> ErrorOr<IterationDecision> {
@@ -225,9 +225,9 @@ struct RelativeTimeFormatImpl {
 
     cldr.unique_formats.generate(generator, "RelativeTimeFormatImpl"sv, "s_relative_time_formats"sv, 10);
 
-    auto append_list = [&](DeprecatedString name, auto const& list) {
+    auto append_list = [&](ByteString name, auto const& list) {
         generator.set("name", name);
-        generator.set("size", DeprecatedString::number(list.size()));
+        generator.set("size", ByteString::number(list.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@relative_time_format_index_type@, @size@> @name@ { {)~~~");
@@ -235,7 +235,7 @@ static constexpr Array<@relative_time_format_index_type@, @size@> @name@ { {)~~~
         bool first = true;
         for (auto index : list) {
             generator.append(first ? " "sv : ", "sv);
-            generator.append(DeprecatedString::number(index));
+            generator.append(ByteString::number(index));
             first = false;
         }
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibTimeZone/GenerateTimeZoneData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibTimeZone/GenerateTimeZoneData.cpp
index 091c029547e..d27d60628a8 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibTimeZone/GenerateTimeZoneData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibTimeZone/GenerateTimeZoneData.cpp
@@ -5,8 +5,8 @@
  */
 
 #include "../LibUnicode/GeneratorUtil.h" // FIXME: Move this somewhere common.
+#include <AK/ByteString.h>
 #include <AK/DateConstants.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Error.h>
 #include <AK/Format.h>
 #include <AK/HashMap.h>
@@ -36,7 +36,7 @@ struct TimeZoneOffset {
     i64 offset { 0 };
     Optional<DateTime> until;
 
-    Optional<DeprecatedString> dst_rule;
+    Optional<ByteString> dst_rule;
     Optional<i32> dst_rule_index;
     i64 dst_offset { 0 };
 
@@ -56,17 +56,17 @@ struct DaylightSavingsOffset {
 struct TimeZoneData {
     UniqueStringStorage unique_strings;
 
-    HashMap<DeprecatedString, Vector<TimeZoneOffset>> time_zones;
-    Vector<DeprecatedString> time_zone_names;
+    HashMap<ByteString, Vector<TimeZoneOffset>> time_zones;
+    Vector<ByteString> time_zone_names;
     Vector<Alias> time_zone_aliases;
 
-    HashMap<DeprecatedString, Vector<DaylightSavingsOffset>> dst_offsets;
-    Vector<DeprecatedString> dst_offset_names;
+    HashMap<ByteString, Vector<DaylightSavingsOffset>> dst_offsets;
+    Vector<ByteString> dst_offset_names;
 
-    HashMap<DeprecatedString, TimeZone::Location> time_zone_coordinates;
+    HashMap<ByteString, TimeZone::Location> time_zone_coordinates;
 
-    HashMap<DeprecatedString, Vector<size_t>> time_zone_regions;
-    Vector<DeprecatedString> time_zone_region_names;
+    HashMap<ByteString, Vector<size_t>> time_zone_regions;
+    Vector<ByteString> time_zone_region_names;
 
     Vector<TimeZone::TimeZoneIdentifier> time_zones_and_links;
 };
@@ -112,10 +112,10 @@ struct AK::Formatter<DaylightSavingsOffset> : Formatter<FormatString> {
     ErrorOr<void> format(FormatBuilder& builder, DaylightSavingsOffset const& dst_offset)
     {
         auto format_time = [&](auto year) {
-            return DeprecatedString::formatted("AK::UnixDateTime::from_unix_time_parts({}, 1, 1, 0, 0, 0, 0)", year);
+            return ByteString::formatted("AK::UnixDateTime::from_unix_time_parts({}, 1, 1, 0, 0, 0, 0)", year);
         };
 
-        static DeprecatedString max_year_as_time("max_year_as_time"sv);
+        static ByteString max_year_as_time("max_year_as_time"sv);
 
         return Formatter<FormatString>::format(builder,
             "{{ {}, {}, {}, {}, {} }}"sv,
@@ -439,7 +439,7 @@ static void set_dst_rule_indices(TimeZoneData& time_zone_data)
     }
 }
 
-static DeprecatedString format_identifier(StringView owner, DeprecatedString identifier)
+static ByteString format_identifier(StringView owner, ByteString identifier)
 {
     constexpr auto gmt_time_zones = Array { "Etc/GMT"sv, "GMT"sv };
 
@@ -448,9 +448,9 @@ static DeprecatedString format_identifier(StringView owner, DeprecatedString ide
             auto offset = identifier.substring_view(gmt_time_zone.length());
 
             if (offset.starts_with('+'))
-                identifier = DeprecatedString::formatted("{}_Ahead_{}", gmt_time_zone, offset.substring_view(1));
+                identifier = ByteString::formatted("{}_Ahead_{}", gmt_time_zone, offset.substring_view(1));
             else if (offset.starts_with('-'))
-                identifier = DeprecatedString::formatted("{}_Behind_{}", gmt_time_zone, offset.substring_view(1));
+                identifier = ByteString::formatted("{}_Behind_{}", gmt_time_zone, offset.substring_view(1));
         }
     }
 
@@ -458,9 +458,9 @@ static DeprecatedString format_identifier(StringView owner, DeprecatedString ide
     identifier = identifier.replace("/"sv, "_"sv, ReplaceMode::All);
 
     if (all_of(identifier, is_ascii_digit))
-        return DeprecatedString::formatted("{}_{}", owner[0], identifier);
+        return ByteString::formatted("{}_{}", owner[0], identifier);
     if (is_ascii_lower_alpha(identifier[0]))
-        return DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
+        return ByteString::formatted("{:c}{}", to_ascii_uppercase(identifier[0]), identifier.substring_view(1));
     return identifier;
 }
 
@@ -568,14 +568,14 @@ struct DaylightSavingsOffset {
     auto append_offsets = [&](auto const& name, auto type, auto const& offsets) {
         generator.set("name", name);
         generator.set("type", type);
-        generator.set("size", DeprecatedString::number(offsets.size()));
+        generator.set("size", ByteString::number(offsets.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {
 )~~~");
 
         for (auto const& offset : offsets)
-            generator.append(DeprecatedString::formatted("    {},\n", offset));
+            generator.append(ByteString::formatted("    {},\n", offset));
 
         generator.append("} };\n");
     };
@@ -597,7 +597,7 @@ static constexpr Array<@type@, @size@> @name@ { {
             auto const& time_zones = time_zone_data.time_zone_regions.find(value)->value;
 
             generator.set("name", name);
-            generator.set("size", DeprecatedString::number(time_zones.size()));
+            generator.set("size", ByteString::number(time_zones.size()));
 
             generator.append(R"~~~(
 static constexpr Array<@string_index_type@, @size@> @name@ { {)~~~");
@@ -605,14 +605,14 @@ static constexpr Array<@string_index_type@, @size@> @name@ { {)~~~");
             bool first = true;
             for (auto const& time_zone : time_zones) {
                 generator.append(first ? " "sv : ", "sv);
-                generator.append(DeprecatedString::number(time_zone));
+                generator.append(ByteString::number(time_zone));
                 first = false;
             }
 
             generator.append(" } };");
         });
 
-    generator.set("size", DeprecatedString::number(time_zone_data.time_zone_names.size()));
+    generator.set("size", ByteString::number(time_zone_data.time_zone_names.size()));
     generator.append(R"~~~(
 static constexpr Array<Location, @size@> s_time_zone_locations { {
 )~~~");
@@ -620,12 +620,12 @@ static constexpr Array<Location, @size@> s_time_zone_locations { {
     for (auto const& time_zone : time_zone_data.time_zone_names) {
         auto location = time_zone_data.time_zone_coordinates.get(time_zone).value_or({});
 
-        generator.append(DeprecatedString::formatted("    {},\n", location));
+        generator.append(ByteString::formatted("    {},\n", location));
     }
     generator.append("} };\n");
 
     auto append_string_conversions = [&](StringView enum_title, StringView enum_snake, auto const& values, Vector<Alias> const& aliases = {}) -> ErrorOr<void> {
-        HashValueMap<DeprecatedString> hashes;
+        HashValueMap<ByteString> hashes;
         TRY(hashes.try_ensure_capacity(values.size()));
 
         auto hash = [](auto const& value) {
@@ -750,10 +750,10 @@ Optional<Array<NamedOffset, 2>> get_named_time_zone_offsets(TimeZone time_zone,
     auto const& time_zone_offset = find_time_zone_offset(time_zone, time);
     Array<NamedOffset, 2> named_offsets;
 
-    auto format_name = [](auto format, auto offset) -> DeprecatedString {
+    auto format_name = [](auto format, auto offset) -> ByteString {
         if (offset == 0)
             return decode_string(format).replace("{}"sv, ""sv, ReplaceMode::FirstOnly);
-        return DeprecatedString::formatted(decode_string(format), decode_string(offset));
+        return ByteString::formatted(decode_string(format), decode_string(offset));
     };
 
     auto set_named_offset = [&](auto& named_offset, auto dst_offset, auto in_dst, auto format, auto offset) {
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateEmojiData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateEmojiData.cpp
index b3870744ce2..65f7ffb007e 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateEmojiData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateEmojiData.cpp
@@ -6,7 +6,7 @@
 
 #include "GeneratorUtil.h"
 #include <AK/AnyOf.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/QuickSort.h>
 #include <AK/SourceGenerator.h>
 #include <AK/StringUtils.h>
@@ -20,11 +20,11 @@ struct Emoji {
     size_t name { 0 };
     Optional<size_t> image_path;
     Unicode::EmojiGroup group;
-    DeprecatedString subgroup;
+    ByteString subgroup;
     u32 display_order { 0 };
     Vector<u32> code_points;
-    DeprecatedString encoded_code_points;
-    DeprecatedString status;
+    ByteString encoded_code_points;
+    ByteString status;
     size_t code_point_array_index { 0 };
 };
 
@@ -45,8 +45,8 @@ static void set_image_path_for_emoji(StringView emoji_resource_path, EmojiData&
         builder.appendff("U+{:X}", code_point);
     }
 
-    auto file = DeprecatedString::formatted("{}.png", builder.to_deprecated_string());
-    auto path = DeprecatedString::formatted("{}/{}", emoji_resource_path, file);
+    auto file = ByteString::formatted("{}.png", builder.to_byte_string());
+    auto path = ByteString::formatted("{}/{}", emoji_resource_path, file);
     if (!FileSystem::exists(path))
         return;
 
@@ -61,7 +61,7 @@ static ErrorOr<void> parse_emoji_test_data(Core::InputBufferedFile& file, EmojiD
     Array<u8, 1024> buffer;
 
     Unicode::EmojiGroup group;
-    DeprecatedString subgroup;
+    ByteString subgroup;
     u32 display_order { 0 };
 
     while (TRY(file.can_read_line())) {
@@ -157,7 +157,7 @@ static ErrorOr<void> parse_emoji_serenity_data(Core::InputBufferedFile& file, Em
             return {};
         }));
 
-        auto name = builder.to_deprecated_string();
+        auto name = builder.to_byte_string();
         if (!any_of(name, is_ascii_lower_alpha))
             name = name.to_titlecase();
 
@@ -218,7 +218,7 @@ static ErrorOr<void> generate_emoji_data_implementation(Core::InputBufferedFile&
     SourceGenerator generator { builder };
 
     generator.set("string_index_type"sv, emoji_data.unique_strings.type_that_fits());
-    generator.set("emojis_size"sv, DeprecatedString::number(emoji_data.emojis.size()));
+    generator.set("emojis_size"sv, ByteString::number(emoji_data.emojis.size()));
 
     generator.append(R"~~~(
 #include <AK/Array.h>
@@ -238,7 +238,7 @@ namespace Unicode {
     for (auto const& emoji : emoji_data.emojis) {
         total_code_point_count += emoji.code_points.size();
     }
-    generator.set("total_code_point_count", DeprecatedString::number(total_code_point_count));
+    generator.set("total_code_point_count", ByteString::number(total_code_point_count));
 
     generator.append(R"~~~(
 static constexpr Array<u32, @total_code_point_count@> s_emoji_code_points { {)~~~");
@@ -247,7 +247,7 @@ static constexpr Array<u32, @total_code_point_count@> s_emoji_code_points { {)~~
     for (auto const& emoji : emoji_data.emojis) {
         for (auto code_point : emoji.code_points) {
             generator.append(first ? " "sv : ", "sv);
-            generator.append(DeprecatedString::formatted("{:#x}", code_point));
+            generator.append(ByteString::formatted("{:#x}", code_point));
             first = false;
         }
     }
@@ -288,12 +288,12 @@ struct EmojiData {
 static constexpr Array<EmojiData, @emojis_size@> s_emojis { {)~~~");
 
     for (auto const& emoji : emoji_data.emojis) {
-        generator.set("name"sv, DeprecatedString::number(emoji.name));
-        generator.set("image_path"sv, DeprecatedString::number(emoji.image_path.value_or(0)));
-        generator.set("group"sv, DeprecatedString::number(to_underlying(emoji.group)));
-        generator.set("display_order"sv, DeprecatedString::number(emoji.display_order));
-        generator.set("code_point_start"sv, DeprecatedString::number(emoji.code_point_array_index));
-        generator.set("code_point_count"sv, DeprecatedString::number(emoji.code_points.size()));
+        generator.set("name"sv, ByteString::number(emoji.name));
+        generator.set("image_path"sv, ByteString::number(emoji.image_path.value_or(0)));
+        generator.set("group"sv, ByteString::number(to_underlying(emoji.group)));
+        generator.set("display_order"sv, ByteString::number(emoji.display_order));
+        generator.set("code_point_start"sv, ByteString::number(emoji.code_point_array_index));
+        generator.set("code_point_count"sv, ByteString::number(emoji.code_points.size()));
 
         generator.append(R"~~~(
     { @name@, @image_path@, @group@, @display_order@, @code_point_start@, @code_point_count@ },)~~~");
@@ -370,7 +370,7 @@ static ErrorOr<void> generate_emoji_installation(Core::InputBufferedFile& file,
 
         generator.append("@emoji@"sv);
         generator.append(" - "sv);
-        generator.append(DeprecatedString::join(" "sv, emoji.code_points, "U+{:X}"sv));
+        generator.append(ByteString::join(" "sv, emoji.code_points, "U+{:X}"sv));
         generator.append(" @name@ (@status@)\n"sv);
     }
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeData.cpp b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeData.cpp
index 95f8f33725d..31fc19dfd9c 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeData.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GenerateUnicodeData.cpp
@@ -7,8 +7,8 @@
 #include "GeneratorUtil.h"
 #include <AK/AllOf.h>
 #include <AK/Array.h>
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Error.h>
 #include <AK/Find.h>
 #include <AK/HashMap.h>
@@ -28,8 +28,8 @@ struct SpecialCasing {
     Vector<u32> lowercase_mapping;
     Vector<u32> uppercase_mapping;
     Vector<u32> titlecase_mapping;
-    DeprecatedString locale;
-    DeprecatedString condition;
+    ByteString locale;
+    ByteString condition;
 };
 
 // https://www.unicode.org/reports/tr44/#CaseFolding.txt
@@ -42,13 +42,13 @@ struct CaseFolding {
 // https://www.unicode.org/reports/tr44/#Character_Decomposition_Mappings
 struct CodePointDecomposition {
     // `tag` is a string since it's used for codegen as an enum value.
-    DeprecatedString tag { "Canonical"sv };
+    ByteString tag { "Canonical"sv };
     size_t decomposition_index { 0 };
     size_t decomposition_size { 0 };
 };
 
 // https://www.unicode.org/reports/tr44/#PropList.txt
-using PropList = HashMap<DeprecatedString, Vector<Unicode::CodePointRange>>;
+using PropList = HashMap<ByteString, Vector<Unicode::CodePointRange>>;
 
 // https://www.unicode.org/reports/tr44/#DerivedNormalizationProps.txt
 enum class QuickCheck {
@@ -63,7 +63,7 @@ struct Normalization {
     QuickCheck quick_check { QuickCheck::Yes };
 };
 
-using NormalizationProps = HashMap<DeprecatedString, Vector<Normalization>>;
+using NormalizationProps = HashMap<ByteString, Vector<Normalization>>;
 
 struct CodePointName {
     Unicode::CodePointRange code_point_range;
@@ -92,16 +92,16 @@ struct CasingTable {
 // https://www.unicode.org/reports/tr44/#UnicodeData.txt
 struct CodePointData {
     u32 code_point { 0 };
-    DeprecatedString name;
+    ByteString name;
     Optional<size_t> abbreviation;
-    DeprecatedString bidi_class;
+    ByteString bidi_class;
     Optional<CodePointDecomposition> decomposition_mapping;
     Optional<i8> numeric_value_decimal;
     Optional<i8> numeric_value_digit;
     Optional<i8> numeric_value_numeric;
     bool bidi_mirrored { false };
-    DeprecatedString unicode_1_name;
-    DeprecatedString iso_comment;
+    ByteString unicode_1_name;
+    ByteString iso_comment;
     CasingTable casing;
 };
 
@@ -127,7 +127,7 @@ struct CodePointTables {
 
 struct CodePointBidiClass {
     Unicode::CodePointRange code_point_range;
-    DeprecatedString bidi_class;
+    ByteString bidi_class;
 };
 
 struct UnicodeData {
@@ -135,12 +135,12 @@ struct UnicodeData {
 
     u32 code_points_with_decomposition_mapping { 0 };
     Vector<u32> decomposition_mappings;
-    Vector<DeprecatedString> compatibility_tags;
+    Vector<ByteString> compatibility_tags;
 
     Vector<SpecialCasing> special_casing;
     u32 largest_special_casing_mapping_size { 0 };
-    Vector<DeprecatedString> conditions;
-    Vector<DeprecatedString> locales;
+    Vector<ByteString> conditions;
+    Vector<ByteString> locales;
 
     Vector<CaseFolding> case_folding;
     u32 largest_case_folding_mapping_size { 0 };
@@ -190,11 +190,11 @@ struct UnicodeData {
     CodePointTables<PropertyTable> word_break_tables;
     CodePointTables<PropertyTable> sentence_break_tables;
 
-    HashTable<DeprecatedString> bidirectional_classes;
+    HashTable<ByteString> bidirectional_classes;
     Vector<CodePointBidiClass> code_point_bidirectional_classes;
 };
 
-static DeprecatedString sanitize_entry(DeprecatedString const& entry)
+static ByteString sanitize_entry(ByteString const& entry)
 {
     auto sanitized = entry.replace("-"sv, "_"sv, ReplaceMode::All);
     sanitized = sanitized.replace(" "sv, "_"sv, ReplaceMode::All);
@@ -209,7 +209,7 @@ static DeprecatedString sanitize_entry(DeprecatedString const& entry)
         next_is_upper = ch == '_';
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 static ErrorOr<void> parse_special_casing(Core::InputBufferedFile& file, UnicodeData& unicode_data)
@@ -248,7 +248,7 @@ static ErrorOr<void> parse_special_casing(Core::InputBufferedFile& file, Unicode
             }
 
             if (!casing.locale.is_empty()) {
-                casing.locale = DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(casing.locale[0]), casing.locale.substring_view(1));
+                casing.locale = ByteString::formatted("{:c}{}", to_ascii_uppercase(casing.locale[0]), casing.locale.substring_view(1));
 
                 if (!unicode_data.locales.contains_slow(casing.locale))
                     unicode_data.locales.append(casing.locale);
@@ -380,7 +380,7 @@ static ErrorOr<void> parse_prop_list(Core::InputBufferedFile& file, PropList& pr
 
 static ErrorOr<void> parse_alias_list(Core::InputBufferedFile& file, PropList const& prop_list, Vector<Alias>& prop_aliases)
 {
-    DeprecatedString current_property;
+    ByteString current_property;
     Array<u8, 1024> buffer;
 
     auto append_alias = [&](auto alias, auto property) {
@@ -455,7 +455,7 @@ static ErrorOr<void> parse_name_aliases(Core::InputBufferedFile& file, UnicodeDa
     return {};
 }
 
-static ErrorOr<void> parse_value_alias_list(Core::InputBufferedFile& file, StringView desired_category, Vector<DeprecatedString> const& value_list, Vector<Alias>& prop_aliases, bool primary_value_is_first = true, bool sanitize_alias = false)
+static ErrorOr<void> parse_value_alias_list(Core::InputBufferedFile& file, StringView desired_category, Vector<ByteString> const& value_list, Vector<Alias>& prop_aliases, bool primary_value_is_first = true, bool sanitize_alias = false)
 {
     TRY(file.seek(0, SeekMode::SetPosition));
     Array<u8, 1024> buffer;
@@ -518,7 +518,7 @@ static ErrorOr<void> parse_normalization_props(Core::InputBufferedFile& file, Un
         VERIFY((segments.size() == 2) || (segments.size() == 3));
 
         auto code_point_range = parse_code_point_range(segments[0].trim_whitespace());
-        auto property = segments[1].trim_whitespace().to_deprecated_string();
+        auto property = segments[1].trim_whitespace().to_byte_string();
 
         Vector<u32> value;
         QuickCheck quick_check = QuickCheck::Yes;
@@ -620,7 +620,7 @@ static Optional<CodePointDecomposition> parse_decomposition_mapping(StringView s
     if (parts.first().starts_with('<')) {
         auto const tag = parts.take_first().trim("<>"sv);
 
-        mapping.tag = DeprecatedString::formatted("{:c}{}", to_ascii_uppercase(tag[0]), tag.substring_view(1));
+        mapping.tag = ByteString::formatted("{:c}{}", to_ascii_uppercase(tag[0]), tag.substring_view(1));
 
         if (!unicode_data.compatibility_tags.contains_slow(mapping.tag))
             unicode_data.compatibility_tags.append(mapping.tag);
@@ -755,15 +755,15 @@ static ErrorOr<void> generate_unicode_data_header(Core::InputBufferedFile& file,
 {
     StringBuilder builder;
     SourceGenerator generator { builder };
-    generator.set("special_casing_mapping_size", DeprecatedString::number(unicode_data.largest_special_casing_mapping_size));
-    generator.set("case_folding_mapping_size", DeprecatedString::number(unicode_data.largest_case_folding_mapping_size));
+    generator.set("special_casing_mapping_size", ByteString::number(unicode_data.largest_special_casing_mapping_size));
+    generator.set("case_folding_mapping_size", ByteString::number(unicode_data.largest_case_folding_mapping_size));
 
     auto generate_enum = [&](StringView name, StringView default_, auto values, Vector<Alias> aliases = {}) {
         quick_sort(values);
         quick_sort(aliases, [](auto& alias1, auto& alias2) { return alias1.alias < alias2.alias; });
 
         generator.set("name", name);
-        generator.set("underlying", DeprecatedString::formatted("{}UnderlyingType", name));
+        generator.set("underlying", ByteString::formatted("{}UnderlyingType", name));
         generator.set("type", ((values.size() + !default_.is_empty()) < 256) ? "u8"sv : "u16"sv);
 
         generator.append(R"~~~(
@@ -872,8 +872,8 @@ static ErrorOr<void> generate_unicode_data_implementation(Core::InputBufferedFil
     SourceGenerator generator { builder };
 
     generator.set("string_index_type"sv, unicode_data.unique_strings.type_that_fits());
-    generator.set("special_casing_size", DeprecatedString::number(unicode_data.special_casing.size()));
-    generator.set("case_folding_size", DeprecatedString::number(unicode_data.case_folding.size()));
+    generator.set("special_casing_size", ByteString::number(unicode_data.special_casing.size()));
+    generator.set("case_folding_size", ByteString::number(unicode_data.case_folding.size()));
 
     generator.set("CODE_POINT_TABLES_LSB_COUNT", TRY(String::number(CODE_POINT_TABLES_LSB_COUNT)));
     generator.set("CODE_POINT_TABLES_LSB_MASK", TRY(String::formatted("{:#x}", CODE_POINT_TABLES_LSB_MASK)));
@@ -884,7 +884,7 @@ static ErrorOr<void> generate_unicode_data_implementation(Core::InputBufferedFil
 #include <AK/CharacterTypes.h>
 #include <AK/Optional.h>
 #include <AK/Span.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringView.h>
 #include <LibUnicode/CharacterTypes.h>
 #include <LibUnicode/UnicodeData.h>
@@ -905,17 +905,17 @@ namespace Unicode {
         generator.append(", {");
         for (auto const& item : list) {
             generator.append(first ? " "sv : ", "sv);
-            generator.append(DeprecatedString::formatted(format, item));
+            generator.append(ByteString::formatted(format, item));
             first = false;
         }
-        generator.append(DeprecatedString::formatted(" }}, {}", list.size()));
+        generator.append(ByteString::formatted(" }}, {}", list.size()));
     };
 
     generator.append(R"~~~(
 static constexpr Array<SpecialCasing, @special_casing_size@> s_special_case { {)~~~");
 
     for (auto const& casing : unicode_data.special_casing) {
-        generator.set("code_point", DeprecatedString::formatted("{:#x}", casing.code_point));
+        generator.set("code_point", ByteString::formatted("{:#x}", casing.code_point));
         generator.append(R"~~~(
     { @code_point@)~~~");
 
@@ -939,7 +939,7 @@ static constexpr Array<SpecialCasing, @special_casing_size@> s_special_case { {)
 static constexpr Array<CaseFolding, @case_folding_size@> s_case_folding { {)~~~");
 
     for (auto const& folding : unicode_data.case_folding) {
-        generator.set("code_point", DeprecatedString::formatted("{:#x}", folding.code_point));
+        generator.set("code_point", ByteString::formatted("{:#x}", folding.code_point));
         generator.set("status", folding.status);
         generator.append(R"~~~(
     { @code_point@, CaseFoldingStatus::@status@)~~~");
@@ -1015,15 +1015,15 @@ struct CodePointBidiClassComparator : public CodePointRangeComparator {
 
 )~~~");
 
-    generator.set("decomposition_mappings_size", DeprecatedString::number(unicode_data.decomposition_mappings.size()));
+    generator.set("decomposition_mappings_size", ByteString::number(unicode_data.decomposition_mappings.size()));
     generator.append("\nstatic constexpr Array<u32, @decomposition_mappings_size@> s_decomposition_mappings_data { ");
-    generator.append(DeprecatedString::join(", "sv, unicode_data.decomposition_mappings, "{:#x}"sv));
+    generator.append(ByteString::join(", "sv, unicode_data.decomposition_mappings, "{:#x}"sv));
     generator.append(" };\n");
 
     auto append_code_point_mappings = [&](StringView name, StringView mapping_type, u32 size, auto mapping_getter) {
         generator.set("name", name);
         generator.set("mapping_type", mapping_type);
-        generator.set("size", DeprecatedString::number(size));
+        generator.set("size", ByteString::number(size));
 
         generator.append(R"~~~(
 static constexpr Array<@mapping_type@, @size@> s_@name@_mappings { {
@@ -1046,16 +1046,16 @@ static constexpr Array<@mapping_type@, @size@> s_@name@_mappings { {
             if (mappings_in_current_row++ > 0)
                 generator.append(" ");
 
-            generator.set("code_point", DeprecatedString::formatted("{:#x}", data.code_point));
+            generator.set("code_point", ByteString::formatted("{:#x}", data.code_point));
             generator.append("{ @code_point@");
 
             if constexpr (IsSame<decltype(mapping), Optional<u32>> || IsSame<decltype(mapping), Optional<size_t>>) {
-                generator.set("mapping", DeprecatedString::formatted("{:#x}", *mapping));
+                generator.set("mapping", ByteString::formatted("{:#x}", *mapping));
                 generator.append(", @mapping@ },");
             } else if constexpr (IsSame<decltype(mapping), Optional<CodePointDecomposition>>) {
                 generator.set("tag", mapping->tag);
-                generator.set("start", DeprecatedString::number(mapping->decomposition_index));
-                generator.set("size", DeprecatedString::number(mapping->decomposition_size));
+                generator.set("start", ByteString::number(mapping->decomposition_index));
+                generator.set("size", ByteString::number(mapping->decomposition_size));
                 generator.append(", CompatibilityFormattingTag::@tag@, @start@, @size@ },");
             } else {
                 append_list_and_size(mapping, "&s_@name@[{}]"sv);
@@ -1195,7 +1195,7 @@ static constexpr Array<@type@, @size@> @name@ { {
 
         generator.set("type", type);
         generator.set("name", name);
-        generator.set("size", DeprecatedString::number(display_names.size()));
+        generator.set("size", ByteString::number(display_names.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@ { {
@@ -1204,9 +1204,9 @@ static constexpr Array<@type@, @size@> @name@ { {
             if (values_in_current_row++ > 0)
                 generator.append(", ");
 
-            generator.set("first", DeprecatedString::formatted("{:#x}", display_name.code_point_range.first));
-            generator.set("last", DeprecatedString::formatted("{:#x}", display_name.code_point_range.last));
-            generator.set("name", DeprecatedString::number(display_name.name));
+            generator.set("first", ByteString::formatted("{:#x}", display_name.code_point_range.first));
+            generator.set("last", ByteString::formatted("{:#x}", display_name.code_point_range.last));
+            generator.set("name", ByteString::number(display_name.name));
             generator.append("{ { @first@, @last@ }, @name@ }");
 
             if (values_in_current_row == max_values_per_row) {
@@ -1226,7 +1226,7 @@ static constexpr Array<@type@, @size@> @name@ { {
         constexpr size_t max_bidi_classes_per_row = 20;
         size_t bidi_classes_in_current_row = 0;
 
-        generator.set("size"sv, DeprecatedString::number(unicode_data.code_point_bidirectional_classes.size()));
+        generator.set("size"sv, ByteString::number(unicode_data.code_point_bidirectional_classes.size()));
         generator.append(R"~~~(
 static constexpr Array<BidiClassData, @size@> s_bidirectional_classes { {
 )~~~");
@@ -1234,8 +1234,8 @@ static constexpr Array<BidiClassData, @size@> s_bidirectional_classes { {
             if (bidi_classes_in_current_row++ > 0)
                 generator.append(", ");
 
-            generator.set("first", DeprecatedString::formatted("{:#x}", data.code_point_range.first));
-            generator.set("last", DeprecatedString::formatted("{:#x}", data.code_point_range.last));
+            generator.set("first", ByteString::formatted("{:#x}", data.code_point_range.first));
+            generator.set("last", ByteString::formatted("{:#x}", data.code_point_range.last));
             generator.set("bidi_class", data.bidi_class);
             generator.append("{ { @first@, @last@ }, BidirectionalClass::@bidi_class@ }");
 
@@ -1274,13 +1274,13 @@ ReadonlySpan<BlockName> block_display_names()
     return display_names.span();
 }
 
-Optional<DeprecatedString> code_point_display_name(u32 code_point)
+Optional<ByteString> code_point_display_name(u32 code_point)
 {
     if (auto const* entry = binary_search(s_code_point_display_names, code_point, nullptr, CodePointNameComparator {})) {
         auto display_name = decode_string(entry->display_name);
 
         if (display_name.ends_with("{:X}"sv))
-            return DeprecatedString::formatted(display_name, code_point);
+            return ByteString::formatted(display_name, code_point);
 
         return display_name;
     }
@@ -1409,7 +1409,7 @@ bool code_point_has_@enum_snake@(u32 code_point, @enum_title@ @enum_snake@)
         ValueFromStringOptions options {};
 
         for (auto const& prop : prop_list) {
-            if constexpr (IsSame<RemoveCVReference<decltype(prop)>, DeprecatedString>) {
+            if constexpr (IsSame<RemoveCVReference<decltype(prop)>, ByteString>) {
                 hashes.set(CaseInsensitiveASCIIStringViewTraits::hash(prop), prop);
                 options.sensitivity = CaseSensitivity::CaseInsensitive;
             } else {
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GeneratorUtil.h b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GeneratorUtil.h
index 03501c5b9c1..e2940c5ebcd 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GeneratorUtil.h
+++ b/Meta/Lagom/Tools/CodeGenerators/LibUnicode/GeneratorUtil.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashFunctions.h>
 #include <AK/HashMap.h>
@@ -101,7 +101,7 @@ public:
     {
         generator.set("type"sv, type);
         generator.set("name"sv, name);
-        generator.set("size"sv, DeprecatedString::number(m_storage.size()));
+        generator.set("size"sv, ByteString::number(m_storage.size()));
 
         generator.append(R"~~~(
 static constexpr Array<@type@, @size@ + 1> @name@ { {
@@ -113,10 +113,10 @@ static constexpr Array<@type@, @size@ + 1> @name@ { {
             if (values_in_current_row++ > 0)
                 generator.append(", ");
 
-            if constexpr (IsSame<StorageType, DeprecatedString>)
-                generator.append(DeprecatedString::formatted("\"{}\"sv", value));
+            if constexpr (IsSame<StorageType, ByteString>)
+                generator.append(ByteString::formatted("\"{}\"sv", value));
             else
-                generator.append(DeprecatedString::formatted("{}", value));
+                generator.append(ByteString::formatted("{}", value));
 
             if (values_in_current_row == max_values_per_row) {
                 values_in_current_row = 0;
@@ -138,8 +138,8 @@ static constexpr Array<@type@, @size@ + 1> @name@ { {
         for (size_t i = 0; i < m_storage.size(); ++i) {
             auto const& list = m_storage[i];
 
-            generator.set("index"sv, DeprecatedString::number(i));
-            generator.set("size"sv, DeprecatedString::number(list.size()));
+            generator.set("index"sv, ByteString::number(i));
+            generator.set("size"sv, ByteString::number(list.size()));
 
             generator.append(R"~~~(
 static constexpr Array<@type@, @size@> @name@@index@ { {)~~~");
@@ -147,14 +147,14 @@ static constexpr Array<@type@, @size@> @name@@index@ { {)~~~");
             bool first = true;
             for (auto const& value : list) {
                 generator.append(first ? " "sv : ", "sv);
-                generator.append(DeprecatedString::formatted("{}", value));
+                generator.append(ByteString::formatted("{}", value));
                 first = false;
             }
 
             generator.append(" } };");
         }
 
-        generator.set("size"sv, DeprecatedString::number(m_storage.size()));
+        generator.set("size"sv, ByteString::number(m_storage.size()));
 
         generator.append(R"~~~(
 
@@ -168,7 +168,7 @@ static constexpr Array<ReadonlySpan<@type@>, @size@ + 1> @name@ { {
             if (values_in_current_row++ > 0)
                 generator.append(", ");
 
-            generator.set("index"sv, DeprecatedString::number(i));
+            generator.set("index"sv, ByteString::number(i));
             generator.append("@name@@index@.span()");
 
             if (values_in_current_row == max_values_per_row) {
@@ -187,8 +187,8 @@ protected:
     HashMap<StorageType, size_t> m_storage_indices;
 };
 
-class UniqueStringStorage : public UniqueStorage<DeprecatedString> {
-    using Base = UniqueStorage<DeprecatedString>;
+class UniqueStringStorage : public UniqueStorage<ByteString> {
+    using Base = UniqueStorage<ByteString>;
 
 public:
     // The goal of the string table generator is to ensure the table is located within the read-only
@@ -204,7 +204,7 @@ public:
             if (values_in_current_row++ > 0)
                 generator.append(", ");
 
-            generator.append(DeprecatedString::formatted("{:#x}", value));
+            generator.append(ByteString::formatted("{:#x}", value));
 
             if (values_in_current_row == max_values_per_row) {
                 values_in_current_row = 0;
@@ -224,7 +224,7 @@ public:
             next_index += string.length() + 2;
         }
 
-        generator.set("size", DeprecatedString::number(next_index));
+        generator.set("size", ByteString::number(next_index));
         generator.append(R"~~~(
 static constexpr Array<u8, @size@> s_encoded_strings { {
     )~~~");
@@ -242,7 +242,7 @@ static constexpr Array<u8, @size@> s_encoded_strings { {
 } };
 )~~~");
 
-        generator.set("size", DeprecatedString::number(string_indices.size()));
+        generator.set("size", ByteString::number(string_indices.size()));
         generator.append(R"~~~(
 static constexpr Array<u32, @size@> s_encoded_string_indices { {
     )~~~");
@@ -276,8 +276,8 @@ static constexpr StringView decode_string(size_t index)
 };
 
 struct Alias {
-    DeprecatedString name;
-    DeprecatedString alias;
+    ByteString name;
+    ByteString alias;
 };
 
 struct CanonicalLanguageID {
@@ -385,11 +385,11 @@ void generate_value_from_string(SourceGenerator& generator, StringView method_na
 {
     ensure_from_string_types_are_generated(generator);
 
-    generator.set("method_name", DeprecatedString::formatted(method_name_format, value_name));
+    generator.set("method_name", ByteString::formatted(method_name_format, value_name));
     generator.set("value_type", value_type);
     generator.set("value_name", value_name);
     generator.set("return_type", options.return_type.has_value() ? *options.return_type : value_type);
-    generator.set("size", DeprecatedString::number(hashes.size()));
+    generator.set("size", ByteString::number(hashes.size()));
 
     generator.append(R"~~~(
 Optional<@return_type@> @method_name@(StringView key)
@@ -408,11 +408,11 @@ Optional<@return_type@> @method_name@(StringView key)
             generator.append(" ");
 
         if constexpr (IsIntegral<ValueType>)
-            generator.set("value"sv, DeprecatedString::number(hashes.get(hash_key).value()));
+            generator.set("value"sv, ByteString::number(hashes.get(hash_key).value()));
         else
-            generator.set("value"sv, DeprecatedString::formatted("{}::{}", value_type, hashes.get(hash_key).value()));
+            generator.set("value"sv, ByteString::formatted("{}::{}", value_type, hashes.get(hash_key).value()));
 
-        generator.set("hash"sv, DeprecatedString::number(hash_key));
+        generator.set("hash"sv, ByteString::number(hash_key));
         generator.append("{ @hash@U, @value@ },"sv);
 
         if (values_in_current_row == max_values_per_row) {
@@ -421,7 +421,7 @@ Optional<@return_type@> @method_name@(StringView key)
         }
     }
 
-    generator.set("return_statement", DeprecatedString::formatted(options.return_format, "value->value"sv));
+    generator.set("return_statement", ByteString::formatted(options.return_format, "value->value"sv));
     generator.append(R"~~~(
     } };
 )~~~");
@@ -445,9 +445,9 @@ Optional<@return_type@> @method_name@(StringView key)
 }
 
 template<typename IdentifierFormatter>
-void generate_value_to_string(SourceGenerator& generator, StringView method_name_format, StringView value_type, StringView value_name, IdentifierFormatter&& format_identifier, ReadonlySpan<DeprecatedString> values)
+void generate_value_to_string(SourceGenerator& generator, StringView method_name_format, StringView value_type, StringView value_name, IdentifierFormatter&& format_identifier, ReadonlySpan<ByteString> values)
 {
-    generator.set("method_name", DeprecatedString::formatted(method_name_format, value_name));
+    generator.set("method_name", ByteString::formatted(method_name_format, value_name));
     generator.set("value_type", value_type);
     generator.set("value_name", value_name);
 
@@ -475,7 +475,7 @@ StringView @method_name@(@value_type@ @value_name@)
 }
 
 template<typename IdentifierFormatter>
-void generate_enum(SourceGenerator& generator, IdentifierFormatter&& format_identifier, StringView name, StringView default_, Vector<DeprecatedString>& values, Vector<Alias> aliases = {})
+void generate_enum(SourceGenerator& generator, IdentifierFormatter&& format_identifier, StringView name, StringView default_, Vector<ByteString>& values, Vector<Alias> aliases = {})
 {
     quick_sort(values, [](auto const& value1, auto const& value2) { return value1.to_lowercase() < value2.to_lowercase(); });
     quick_sort(aliases, [](auto const& alias1, auto const& alias2) { return alias1.alias.to_lowercase() < alias2.alias.to_lowercase(); });
@@ -514,20 +514,20 @@ template<typename LocalesType, typename IdentifierFormatter, typename ListFormat
 void generate_mapping(SourceGenerator& generator, LocalesType const& locales, StringView type, StringView name, StringView format, IdentifierFormatter&& format_identifier, ListFormatter&& format_list)
 {
     auto format_mapping_name = [&](StringView format, StringView name) {
-        DeprecatedString mapping_name;
+        ByteString mapping_name;
 
         if constexpr (IsNullPointer<IdentifierFormatter>)
             mapping_name = name.replace("-"sv, "_"sv, ReplaceMode::All);
         else
             mapping_name = format_identifier(type, name);
 
-        return DeprecatedString::formatted(format, mapping_name.to_lowercase());
+        return ByteString::formatted(format, mapping_name.to_lowercase());
     };
 
-    Vector<DeprecatedString> mapping_names;
+    Vector<ByteString> mapping_names;
 
     for (auto const& locale : locales) {
-        DeprecatedString mapping_name;
+        ByteString mapping_name;
 
         if constexpr (requires { locale.key; }) {
             mapping_name = format_mapping_name(format, locale.key);
@@ -544,7 +544,7 @@ void generate_mapping(SourceGenerator& generator, LocalesType const& locales, St
 
     generator.set("type", type);
     generator.set("name", name);
-    generator.set("size", DeprecatedString::number(locales.size()));
+    generator.set("size", ByteString::number(locales.size()));
     generator.append(R"~~~(
 static constexpr Array<ReadonlySpan<@type@>, @size@> @name@ { {
     )~~~");
@@ -589,9 +589,9 @@ ReadonlySpan<StringView> @name@()
         first = false;
 
         if (auto it = aliases.find_if([&](auto const& alias) { return alias.alias == value; }); it != aliases.end())
-            generator.append(DeprecatedString::formatted("\"{}\"sv", it->name));
+            generator.append(ByteString::formatted("\"{}\"sv", it->name));
         else
-            generator.append(DeprecatedString::formatted("\"{}\"sv", value));
+            generator.append(ByteString::formatted("\"{}\"sv", value));
     }
 
     generator.append(R"~~~( };
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
index f3fdc897dee..f9716649547 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
@@ -112,7 +112,7 @@ static StringView sequence_storage_type_to_cpp_storage_type_name(SequenceStorage
 
 CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface);
 
-static DeprecatedString union_type_to_variant(UnionType const& union_type, Interface const& interface)
+static ByteString union_type_to_variant(UnionType const& union_type, Interface const& interface)
 {
     StringBuilder builder;
     builder.append("Variant<"sv);
@@ -132,16 +132,16 @@ static DeprecatedString union_type_to_variant(UnionType const& union_type, Inter
         builder.append(", Empty"sv);
 
     builder.append('>');
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
 {
     if (is_platform_object(type) || type.name() == "WindowProxy"sv)
-        return { .name = DeprecatedString::formatted("JS::Handle<{}>", type.name()), .sequence_storage_type = SequenceStorageType::MarkedVector };
+        return { .name = ByteString::formatted("JS::Handle<{}>", type.name()), .sequence_storage_type = SequenceStorageType::MarkedVector };
 
     if (is_javascript_builtin(type))
-        return { .name = DeprecatedString::formatted("JS::Handle<JS::{}>", type.name()), .sequence_storage_type = SequenceStorageType::MarkedVector };
+        return { .name = ByteString::formatted("JS::Handle<JS::{}>", type.name()), .sequence_storage_type = SequenceStorageType::MarkedVector };
 
     if (interface.callback_functions.contains(type.name()))
         return { .name = "JS::Handle<WebIDL::CallbackType>", .sequence_storage_type = SequenceStorageType::MarkedVector };
@@ -200,7 +200,7 @@ CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
         if (sequence_cpp_type.sequence_storage_type == SequenceStorageType::MarkedVector)
             return { .name = storage_type_name, .sequence_storage_type = SequenceStorageType::Vector };
 
-        return { .name = DeprecatedString::formatted("{}<{}>", storage_type_name, sequence_cpp_type.name), .sequence_storage_type = SequenceStorageType::Vector };
+        return { .name = ByteString::formatted("{}<{}>", storage_type_name, sequence_cpp_type.name), .sequence_storage_type = SequenceStorageType::Vector };
     }
 
     if (type.name() == "record") {
@@ -210,7 +210,7 @@ CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
         auto record_key_cpp_type = idl_type_name_to_cpp_type(record_key_type, interface);
         auto record_value_cpp_type = idl_type_name_to_cpp_type(record_value_type, interface);
 
-        return { .name = DeprecatedString::formatted("OrderedHashMap<{}, {}>", record_key_cpp_type.name, record_value_cpp_type.name), .sequence_storage_type = SequenceStorageType::Vector };
+        return { .name = ByteString::formatted("OrderedHashMap<{}, {}>", record_key_cpp_type.name, record_value_cpp_type.name), .sequence_storage_type = SequenceStorageType::Vector };
     }
 
     if (is<UnionType>(type)) {
@@ -229,13 +229,13 @@ CppType idl_type_name_to_cpp_type(Type const& type, Interface const& interface)
     TODO();
 }
 
-static DeprecatedString make_input_acceptable_cpp(DeprecatedString const& input)
+static ByteString make_input_acceptable_cpp(ByteString const& input)
 {
     if (input.is_one_of("class", "template", "for", "default", "char", "namespace", "delete", "inline")) {
         StringBuilder builder;
         builder.append(input);
         builder.append('_');
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 
     return input.replace("-"sv, "_"sv, ReplaceMode::All);
@@ -266,7 +266,7 @@ static void generate_include_for(auto& generator, auto& path)
     }
 
     LexicalPath include_path { path_string };
-    forked_generator.set("include.path", DeprecatedString::formatted("{}/{}.h", include_path.dirname(), include_path.title()));
+    forked_generator.set("include.path", ByteString::formatted("{}/{}.h", include_path.dirname(), include_path.title()));
     forked_generator.append(R"~~~(
 #include <@include.path@>
 )~~~");
@@ -275,7 +275,7 @@ static void generate_include_for(auto& generator, auto& path)
 static void emit_includes_for_all_imports(auto& interface, auto& generator, bool is_iterator = false)
 {
     Queue<RemoveCVReference<decltype(interface)> const*> interfaces;
-    HashTable<DeprecatedString> paths_imported;
+    HashTable<ByteString> paths_imported;
 
     interfaces.enqueue(&interface);
 
@@ -297,13 +297,13 @@ static void emit_includes_for_all_imports(auto& interface, auto& generator, bool
     }
 
     if (is_iterator) {
-        auto iterator_path = DeprecatedString::formatted("{}Iterator", interface.fully_qualified_name.replace("::"sv, "/"sv, ReplaceMode::All));
+        auto iterator_path = ByteString::formatted("{}Iterator", interface.fully_qualified_name.replace("::"sv, "/"sv, ReplaceMode::All));
         generate_include_for_iterator(generator, iterator_path);
     }
 }
 
 template<typename ParameterType>
-static void generate_to_string(SourceGenerator& scoped_generator, ParameterType const& parameter, bool variadic, bool optional, Optional<DeprecatedString> const& optional_default_value)
+static void generate_to_string(SourceGenerator& scoped_generator, ParameterType const& parameter, bool variadic, bool optional, Optional<ByteString> const& optional_default_value)
 {
     if (variadic) {
         scoped_generator.append(R"~~~(
@@ -363,7 +363,7 @@ static void generate_to_string(SourceGenerator& scoped_generator, ParameterType
 }
 
 template<typename ParameterType>
-static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter, DeprecatedString const& js_name, DeprecatedString const& js_suffix, DeprecatedString const& cpp_name, IDL::Interface const& interface, bool legacy_null_to_empty_string = false, bool optional = false, Optional<DeprecatedString> optional_default_value = {}, bool variadic = false, size_t recursion_depth = 0)
+static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter, ByteString const& js_name, ByteString const& js_suffix, ByteString const& cpp_name, IDL::Interface const& interface, bool legacy_null_to_empty_string = false, bool optional = false, Optional<ByteString> optional_default_value = {}, bool variadic = false, size_t recursion_depth = 0)
 {
     auto scoped_generator = generator.fork();
     auto acceptable_cpp_name = make_input_acceptable_cpp(cpp_name);
@@ -698,7 +698,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         auto default_value_cpp_name = enumeration.translated_cpp_names.get(enum_member_name);
         VERIFY(default_value_cpp_name.has_value());
         enum_generator.set("enum.default.cpp_value", *default_value_cpp_name);
-        enum_generator.set("js_name.as_string", DeprecatedString::formatted("{}{}_string", enum_generator.get("js_name"sv), enum_generator.get("js_suffix"sv)));
+        enum_generator.set("js_name.as_string", ByteString::formatted("{}{}_string", enum_generator.get("js_name"sv), enum_generator.get("js_suffix"sv)));
         enum_generator.append(R"~~~(
     @parameter.type.name@ @cpp_name@ { @parameter.type.name@::@enum.default.cpp_value@ };
 )~~~");
@@ -761,8 +761,8 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
             for (auto& member : current_dictionary->members) {
                 dictionary_generator.set("member_key", member.name);
                 auto member_js_name = make_input_acceptable_cpp(member.name.to_snakecase());
-                auto member_value_name = DeprecatedString::formatted("{}_value_{}", member_js_name, i);
-                auto member_property_value_name = DeprecatedString::formatted("{}_property_value_{}", member_js_name, i);
+                auto member_value_name = ByteString::formatted("{}_value_{}", member_js_name, i);
+                auto member_property_value_name = ByteString::formatted("{}_property_value_{}", member_js_name, i);
                 dictionary_generator.set("member_name", member_js_name);
                 dictionary_generator.set("member_value_name", member_value_name);
                 dictionary_generator.set("member_property_value_name", member_property_value_name);
@@ -848,7 +848,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         auto sequence_generator = scoped_generator.fork();
         auto& parameterized_type = verify_cast<IDL::ParameterizedType>(*parameter.type);
-        sequence_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
+        sequence_generator.set("recursion_depth", ByteString::number(recursion_depth));
 
         // An ECMAScript value V is converted to an IDL sequence<T> value as follows:
         // 1. If Type(V) is not Object, throw a TypeError.
@@ -900,7 +900,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotIterable, @js_name@@js_suffix@.to_string_without_side_effects());
 )~~~");
 
-        parameterized_type.generate_sequence_from_iterable(sequence_generator, DeprecatedString::formatted("{}{}", acceptable_cpp_name, optional ? "_non_optional" : ""), DeprecatedString::formatted("{}{}", js_name, js_suffix), DeprecatedString::formatted("iterator_method{}", recursion_depth), interface, recursion_depth + 1);
+        parameterized_type.generate_sequence_from_iterable(sequence_generator, ByteString::formatted("{}{}", acceptable_cpp_name, optional ? "_non_optional" : ""), ByteString::formatted("{}{}", js_name, js_suffix), ByteString::formatted("iterator_method{}", recursion_depth), interface, recursion_depth + 1);
 
         if (optional) {
             sequence_generator.append(R"~~~(
@@ -913,7 +913,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         auto record_generator = scoped_generator.fork();
         auto& parameterized_type = verify_cast<IDL::ParameterizedType>(*parameter.type);
-        record_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
+        record_generator.set("recursion_depth", ByteString::number(recursion_depth));
 
         // A record can only have two types: key type and value type.
         VERIFY(parameterized_type.parameters().size() == 2);
@@ -963,7 +963,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 )~~~");
 
         IDL::Parameter key_parameter { .type = parameterized_type.parameters()[0], .name = acceptable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
-        generate_to_cpp(record_generator, key_parameter, "key", DeprecatedString::number(recursion_depth), DeprecatedString::formatted("typed_key{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
+        generate_to_cpp(record_generator, key_parameter, "key", ByteString::number(recursion_depth), ByteString::formatted("typed_key{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
 
         record_generator.append(R"~~~(
         auto value@recursion_depth@ = TRY(@js_name@@js_suffix@_object.get(property_key@recursion_depth@));
@@ -971,7 +971,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         // FIXME: Record value types should be TypeWithExtendedAttributes, which would allow us to get [LegacyNullToEmptyString] here.
         IDL::Parameter value_parameter { .type = parameterized_type.parameters()[1], .name = acceptable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
-        generate_to_cpp(record_generator, value_parameter, "value", DeprecatedString::number(recursion_depth), DeprecatedString::formatted("typed_value{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
+        generate_to_cpp(record_generator, value_parameter, "value", ByteString::number(recursion_depth), ByteString::formatted("typed_value{}", recursion_depth), interface, false, false, {}, false, recursion_depth + 1);
 
         record_generator.append(R"~~~(
         @cpp_name@.set(typed_key@recursion_depth@, typed_value@recursion_depth@);
@@ -984,7 +984,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
         auto& union_type = verify_cast<IDL::UnionType>(*parameter.type);
         union_generator.set("union_type", union_type_to_variant(union_type, interface));
-        union_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
+        union_generator.set("recursion_depth", ByteString::number(recursion_depth));
 
         // NOTE: This is handled out here as we need the dictionary conversion code for the {} optional default value.
         // 3. Let types be the flattened member types of the union type.
@@ -1036,9 +1036,9 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         to_variant_captures.append("&vm, &realm"sv);
 
         if (dictionary_type)
-            to_variant_captures.append(DeprecatedString::formatted(", &{}{}_to_dictionary", js_name, js_suffix));
+            to_variant_captures.append(ByteString::formatted(", &{}{}_to_dictionary", js_name, js_suffix));
 
-        union_generator.set("to_variant_captures", to_variant_captures.to_deprecated_string());
+        union_generator.set("to_variant_captures", to_variant_captures.to_byte_string());
 
         union_generator.append(R"~~~(
     auto @js_name@@js_suffix@_to_variant = [@to_variant_captures@](JS::Value @js_name@@js_suffix@) -> JS::ThrowCompletionOr<@union_type@> {
@@ -1211,7 +1211,7 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
         if (method) {
 )~~~");
 
-            sequence_type->generate_sequence_from_iterable(union_generator, acceptable_cpp_name, DeprecatedString::formatted("{}{}", js_name, js_suffix), "method", interface, recursion_depth + 1);
+            sequence_type->generate_sequence_from_iterable(union_generator, acceptable_cpp_name, ByteString::formatted("{}{}", js_name, js_suffix), "method", interface, recursion_depth + 1);
 
             union_generator.append(R"~~~(
 
@@ -1296,8 +1296,8 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 )~~~");
             // NOTE: generate_to_cpp doesn't use the parameter name.
             // NOTE: generate_to_cpp will use to_{u32,etc.} which uses to_number internally and will thus use TRY, but it cannot throw as we know we are dealing with a number.
-            IDL::Parameter parameter { .type = *numeric_type, .name = DeprecatedString::empty(), .optional_default_value = {}, .extended_attributes = {} };
-            generate_to_cpp(union_generator, parameter, js_name, js_suffix, DeprecatedString::formatted("{}{}_number", js_name, js_suffix), interface, false, false, {}, false, recursion_depth + 1);
+            IDL::Parameter parameter { .type = *numeric_type, .name = ByteString::empty(), .optional_default_value = {}, .extended_attributes = {} };
+            generate_to_cpp(union_generator, parameter, js_name, js_suffix, ByteString::formatted("{}{}_number", js_name, js_suffix), interface, false, false, {}, false, recursion_depth + 1);
 
             union_generator.append(R"~~~(
             return { @js_name@@js_suffix@_number };
@@ -1361,8 +1361,8 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
             // NOTE: generate_to_cpp doesn't use the parameter name.
             // NOTE: generate_to_cpp will use to_{u32,etc.} which uses to_number internally and will thus use TRY, but it cannot throw as we know we are dealing with a number.
-            IDL::Parameter parameter { .type = *numeric_type, .name = DeprecatedString::empty(), .optional_default_value = {}, .extended_attributes = {} };
-            generate_to_cpp(union_numeric_type_generator, parameter, "x", DeprecatedString::empty(), "x_number", interface, false, false, {}, false, recursion_depth + 1);
+            IDL::Parameter parameter { .type = *numeric_type, .name = ByteString::empty(), .optional_default_value = {}, .extended_attributes = {} };
+            generate_to_cpp(union_numeric_type_generator, parameter, "x", ByteString::empty(), "x_number", interface, false, false, {}, false, recursion_depth + 1);
 
             union_numeric_type_generator.append(R"~~~(
         return x_number;
@@ -1372,8 +1372,8 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
 
             // NOTE: generate_to_cpp doesn't use the parameter name.
             // NOTE: generate_to_cpp will use to_{u32,etc.} which uses to_number internally and will thus use TRY, but it cannot throw as we know we are dealing with a number.
-            IDL::Parameter parameter { .type = *numeric_type, .name = DeprecatedString::empty(), .optional_default_value = {}, .extended_attributes = {} };
-            generate_to_cpp(union_generator, parameter, js_name, js_suffix, DeprecatedString::formatted("{}{}_number", js_name, js_suffix), interface, false, false, {}, false, recursion_depth + 1);
+            IDL::Parameter parameter { .type = *numeric_type, .name = ByteString::empty(), .optional_default_value = {}, .extended_attributes = {} };
+            generate_to_cpp(union_generator, parameter, js_name, js_suffix, ByteString::formatted("{}{}_number", js_name, js_suffix), interface, false, false, {}, false, recursion_depth + 1);
 
             union_generator.append(R"~~~(
         return { @js_name@@js_suffix@_number };
@@ -1457,21 +1457,21 @@ static void generate_to_cpp(SourceGenerator& generator, ParameterType& parameter
     }
 }
 
-static void generate_argument_count_check(SourceGenerator& generator, DeprecatedString const& function_name, size_t argument_count)
+static void generate_argument_count_check(SourceGenerator& generator, ByteString const& function_name, size_t argument_count)
 {
     if (argument_count == 0)
         return;
 
     auto argument_count_check_generator = generator.fork();
     argument_count_check_generator.set("function.name", function_name);
-    argument_count_check_generator.set("function.nargs", DeprecatedString::number(argument_count));
+    argument_count_check_generator.set("function.nargs", ByteString::number(argument_count));
 
     if (argument_count == 1) {
         argument_count_check_generator.set(".bad_arg_count", "JS::ErrorType::BadArgCountOne");
         argument_count_check_generator.set(".arg_count_suffix", "");
     } else {
         argument_count_check_generator.set(".bad_arg_count", "JS::ErrorType::BadArgCountMany");
-        argument_count_check_generator.set(".arg_count_suffix", DeprecatedString::formatted(", \"{}\"", argument_count));
+        argument_count_check_generator.set(".arg_count_suffix", ByteString::formatted(", \"{}\"", argument_count));
     }
 
     argument_count_check_generator.append(R"~~~(
@@ -1484,7 +1484,7 @@ static void generate_arguments(SourceGenerator& generator, Vector<IDL::Parameter
 {
     auto arguments_generator = generator.fork();
 
-    Vector<DeprecatedString> parameter_names;
+    Vector<ByteString> parameter_names;
     size_t argument_index = 0;
     for (auto& parameter : parameters) {
         auto parameter_name = make_input_acceptable_cpp(parameter.name.to_snakecase());
@@ -1492,18 +1492,18 @@ static void generate_arguments(SourceGenerator& generator, Vector<IDL::Parameter
         if (parameter.variadic) {
             // JS::MarkedVector is non-copyable, and the implementations likely want ownership of the
             // list, so we move() it into the parameter list.
-            parameter_names.append(DeprecatedString::formatted("move({})", parameter_name));
+            parameter_names.append(ByteString::formatted("move({})", parameter_name));
         } else {
             parameter_names.append(move(parameter_name));
 
-            arguments_generator.set("argument.index", DeprecatedString::number(argument_index));
+            arguments_generator.set("argument.index", ByteString::number(argument_index));
             arguments_generator.append(R"~~~(
     auto arg@argument.index@ = vm.argument(@argument.index@);
 )~~~");
         }
 
         bool legacy_null_to_empty_string = parameter.extended_attributes.contains("LegacyNullToEmptyString");
-        generate_to_cpp(generator, parameter, "arg", DeprecatedString::number(argument_index), parameter.name.to_snakecase(), interface, legacy_null_to_empty_string, parameter.optional, parameter.optional_default_value, parameter.variadic, 0);
+        generate_to_cpp(generator, parameter, "arg", ByteString::number(argument_index), parameter.name.to_snakecase(), interface, legacy_null_to_empty_string, parameter.optional, parameter.optional_default_value, parameter.variadic, 0);
         ++argument_index;
     }
 
@@ -1511,13 +1511,13 @@ static void generate_arguments(SourceGenerator& generator, Vector<IDL::Parameter
 }
 
 // https://webidl.spec.whatwg.org/#create-sequence-from-iterable
-void IDL::ParameterizedType::generate_sequence_from_iterable(SourceGenerator& generator, DeprecatedString const& cpp_name, DeprecatedString const& iterable_cpp_name, DeprecatedString const& iterator_method_cpp_name, IDL::Interface const& interface, size_t recursion_depth) const
+void IDL::ParameterizedType::generate_sequence_from_iterable(SourceGenerator& generator, ByteString const& cpp_name, ByteString const& iterable_cpp_name, ByteString const& iterator_method_cpp_name, IDL::Interface const& interface, size_t recursion_depth) const
 {
     auto sequence_generator = generator.fork();
     sequence_generator.set("cpp_name", cpp_name);
     sequence_generator.set("iterable_cpp_name", iterable_cpp_name);
     sequence_generator.set("iterator_method_cpp_name", iterator_method_cpp_name);
-    sequence_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
+    sequence_generator.set("recursion_depth", ByteString::number(recursion_depth));
     auto sequence_cpp_type = idl_type_name_to_cpp_type(parameters().first(), interface);
     sequence_generator.set("sequence.type", sequence_cpp_type.name);
     sequence_generator.set("sequence.storage_type", sequence_storage_type_to_cpp_storage_type_name(sequence_cpp_type.sequence_storage_type));
@@ -1558,7 +1558,7 @@ void IDL::ParameterizedType::generate_sequence_from_iterable(SourceGenerator& ge
 
     // FIXME: Sequences types should be TypeWithExtendedAttributes, which would allow us to get [LegacyNullToEmptyString] here.
     IDL::Parameter parameter { .type = parameters().first(), .name = iterable_cpp_name, .optional_default_value = {}, .extended_attributes = {} };
-    generate_to_cpp(sequence_generator, parameter, "next_item", DeprecatedString::number(recursion_depth), DeprecatedString::formatted("sequence_item{}", recursion_depth), interface, false, false, {}, false, recursion_depth);
+    generate_to_cpp(sequence_generator, parameter, "next_item", ByteString::number(recursion_depth), ByteString::formatted("sequence_item{}", recursion_depth), interface, false, false, {}, false, recursion_depth);
 
     sequence_generator.append(R"~~~(
         @cpp_name@.append(sequence_item@recursion_depth@);
@@ -1571,13 +1571,13 @@ enum class WrappingReference {
     Yes,
 };
 
-static void generate_wrap_statement(SourceGenerator& generator, DeprecatedString const& value, IDL::Type const& type, IDL::Interface const& interface, StringView result_expression, WrappingReference wrapping_reference = WrappingReference::No, size_t recursion_depth = 0)
+static void generate_wrap_statement(SourceGenerator& generator, ByteString const& value, IDL::Type const& type, IDL::Interface const& interface, StringView result_expression, WrappingReference wrapping_reference = WrappingReference::No, size_t recursion_depth = 0)
 {
     auto scoped_generator = generator.fork();
     scoped_generator.set("value", value);
     if (!libweb_interface_namespaces.span().contains_slow(type.name())) {
         if (is_javascript_builtin(type))
-            scoped_generator.set("type", DeprecatedString::formatted("JS::{}", type.name()));
+            scoped_generator.set("type", ByteString::formatted("JS::{}", type.name()));
         else
             scoped_generator.set("type", type.name());
     } else {
@@ -1586,10 +1586,10 @@ static void generate_wrap_statement(SourceGenerator& generator, DeprecatedString
         builder.append(type.name());
         builder.append("::"sv);
         builder.append(type.name());
-        scoped_generator.set("type", builder.to_deprecated_string());
+        scoped_generator.set("type", builder.to_byte_string());
     }
     scoped_generator.set("result_expression", result_expression);
-    scoped_generator.set("recursion_depth", DeprecatedString::number(recursion_depth));
+    scoped_generator.set("recursion_depth", ByteString::number(recursion_depth));
 
     if (type.name() == "undefined") {
         scoped_generator.append(R"~~~(
@@ -1665,7 +1665,7 @@ static void generate_wrap_statement(SourceGenerator& generator, DeprecatedString
             auto* wrapped_element@recursion_depth@ = &(*element@recursion_depth@);
 )~~~");
         } else {
-            generate_wrap_statement(scoped_generator, DeprecatedString::formatted("element{}", recursion_depth), sequence_generic_type.parameters().first(), interface, DeprecatedString::formatted("auto wrapped_element{} =", recursion_depth), WrappingReference::Yes, recursion_depth + 1);
+            generate_wrap_statement(scoped_generator, ByteString::formatted("element{}", recursion_depth), sequence_generic_type.parameters().first(), interface, ByteString::formatted("auto wrapped_element{} =", recursion_depth), WrappingReference::Yes, recursion_depth + 1);
         }
 
         scoped_generator.append(R"~~~(
@@ -1730,7 +1730,7 @@ static void generate_wrap_statement(SourceGenerator& generator, DeprecatedString
 )~~~");
 
             // NOTE: While we are using const&, the underlying type for wrappable types in unions is (Nonnull)RefPtr, which are not references.
-            generate_wrap_statement(union_generator, DeprecatedString::formatted("visited_union_value{}", recursion_depth), current_union_type, interface, "return"sv, WrappingReference::No, recursion_depth + 1);
+            generate_wrap_statement(union_generator, ByteString::formatted("visited_union_value{}", recursion_depth), current_union_type, interface, "return"sv, WrappingReference::No, recursion_depth + 1);
 
             // End of current visit lambda.
             // The last lambda cannot have a trailing comma on the closing brace, unless the type is nullable, where an extra lambda will be generated for the Empty case.
@@ -1760,7 +1760,7 @@ static void generate_wrap_statement(SourceGenerator& generator, DeprecatedString
     } else if (interface.enumerations.contains(type.name())) {
         // Handle Enum? values, which were null-checked above
         if (type.is_nullable())
-            scoped_generator.set("value", DeprecatedString::formatted("{}.value()", value));
+            scoped_generator.set("value", ByteString::formatted("{}.value()", value));
         scoped_generator.append(R"~~~(
     @result_expression@ JS::PrimitiveString::create(vm, Bindings::idl_enum_to_string(@value@));
 )~~~");
@@ -1796,18 +1796,18 @@ static void generate_wrap_statement(SourceGenerator& generator, DeprecatedString
         while (true) {
             for (auto& member : current_dictionary->members) {
                 dictionary_generator.set("member_key", member.name);
-                auto member_key_js_name = DeprecatedString::formatted("{}{}", make_input_acceptable_cpp(member.name.to_snakecase()), recursion_depth);
+                auto member_key_js_name = ByteString::formatted("{}{}", make_input_acceptable_cpp(member.name.to_snakecase()), recursion_depth);
                 dictionary_generator.set("member_name", member_key_js_name);
-                auto member_value_js_name = DeprecatedString::formatted("{}_value", member_key_js_name);
+                auto member_value_js_name = ByteString::formatted("{}_value", member_key_js_name);
                 dictionary_generator.set("member_value", member_value_js_name);
 
-                auto wrapped_value_name = DeprecatedString::formatted("wrapped_{}", member_value_js_name);
+                auto wrapped_value_name = ByteString::formatted("wrapped_{}", member_value_js_name);
                 dictionary_generator.set("wrapped_value_name", wrapped_value_name);
 
                 dictionary_generator.append(R"~~~(
     JS::Value @wrapped_value_name@;
 )~~~");
-                generate_wrap_statement(dictionary_generator, DeprecatedString::formatted("{}.{}", value, member.name.to_snakecase()), member.type, interface, DeprecatedString::formatted("{} =", wrapped_value_name), WrappingReference::No, recursion_depth + 1);
+                generate_wrap_statement(dictionary_generator, ByteString::formatted("{}.{}", value, member.name.to_snakecase()), member.type, interface, ByteString::formatted("{} =", wrapped_value_name), WrappingReference::No, recursion_depth + 1);
 
                 dictionary_generator.append(R"~~~(
     MUST(dictionary_object@recursion_depth@->create_data_property("@member_key@", @wrapped_value_name@));
@@ -1856,23 +1856,23 @@ static void generate_return_statement(SourceGenerator& generator, IDL::Type cons
     return generate_wrap_statement(generator, "retval", return_type, interface, "return"sv);
 }
 
-static void generate_variable_statement(SourceGenerator& generator, DeprecatedString const& variable_name, IDL::Type const& value_type, DeprecatedString const& value_name, IDL::Interface const& interface)
+static void generate_variable_statement(SourceGenerator& generator, ByteString const& variable_name, IDL::Type const& value_type, ByteString const& value_name, IDL::Interface const& interface)
 {
     auto variable_generator = generator.fork();
     variable_generator.set("variable_name", variable_name);
     variable_generator.append(R"~~~(
     JS::Value @variable_name@;
 )~~~");
-    return generate_wrap_statement(generator, value_name, value_type, interface, DeprecatedString::formatted("{} = ", variable_name));
+    return generate_wrap_statement(generator, value_name, value_type, interface, ByteString::formatted("{} = ", variable_name));
 }
 
-static void generate_function(SourceGenerator& generator, IDL::Function const& function, StaticFunction is_static_function, DeprecatedString const& class_name, DeprecatedString const& interface_fully_qualified_name, IDL::Interface const& interface)
+static void generate_function(SourceGenerator& generator, IDL::Function const& function, StaticFunction is_static_function, ByteString const& class_name, ByteString const& interface_fully_qualified_name, IDL::Interface const& interface)
 {
     auto function_generator = generator.fork();
     function_generator.set("class_name", class_name);
     function_generator.set("interface_fully_qualified_name", interface_fully_qualified_name);
     function_generator.set("function.name:snakecase", make_input_acceptable_cpp(function.name.to_snakecase()));
-    function_generator.set("overload_suffix", function.is_overloaded ? DeprecatedString::number(function.overload_index) : DeprecatedString::empty());
+    function_generator.set("overload_suffix", function.is_overloaded ? ByteString::number(function.overload_index) : ByteString::empty());
 
     if (function.extended_attributes.contains("ImplementedAs")) {
         auto implemented_as = function.extended_attributes.get("ImplementedAs").value();
@@ -1941,7 +1941,7 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@@overload_suffi
         if (arguments_builder.is_empty())
             function_generator.set(".arguments", "vm");
         else
-            function_generator.set(".arguments", DeprecatedString::formatted("vm, {}", arguments_builder.string_view()));
+            function_generator.set(".arguments", ByteString::formatted("vm, {}", arguments_builder.string_view()));
 
         function_generator.append(R"~~~(
     [[maybe_unused]] auto retval = TRY(throw_dom_exception_if_needed(vm, [&] { return @interface_fully_qualified_name@::@function.cpp_name@(@.arguments@); }));
@@ -2082,7 +2082,7 @@ static Vector<EffectiveOverloadSet::Item> compute_the_effective_overload_set(aut
     return overloads;
 }
 
-static DeprecatedString generate_constructor_for_idl_type(Type const& type)
+static ByteString generate_constructor_for_idl_type(Type const& type)
 {
     auto append_type_list = [](auto& builder, auto const& type_list) {
         bool first = true;
@@ -2099,14 +2099,14 @@ static DeprecatedString generate_constructor_for_idl_type(Type const& type)
 
     switch (type.kind()) {
     case Type::Kind::Plain:
-        return DeprecatedString::formatted("make_ref_counted<IDL::Type>(\"{}\", {})", type.name(), type.is_nullable());
+        return ByteString::formatted("make_ref_counted<IDL::Type>(\"{}\", {})", type.name(), type.is_nullable());
     case Type::Kind::Parameterized: {
         auto const& parameterized_type = type.as_parameterized();
         StringBuilder builder;
         builder.appendff("make_ref_counted<IDL::ParameterizedType>(\"{}\", {}, Vector<NonnullRefPtr<IDL::Type const>> {{", type.name(), type.is_nullable());
         append_type_list(builder, parameterized_type.parameters());
         builder.append("})"sv);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
     case Type::Kind::Union: {
         auto const& union_type = type.as_union();
@@ -2114,7 +2114,7 @@ static DeprecatedString generate_constructor_for_idl_type(Type const& type)
         builder.appendff("make_ref_counted<IDL::UnionType>(\"{}\", {}, Vector<NonnullRefPtr<IDL::Type const>> {{", type.name(), type.is_nullable());
         append_type_list(builder, union_type.member_types());
         builder.append("})"sv);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
     }
 
@@ -2145,7 +2145,7 @@ static size_t resolve_distinguishing_argument_index(Interface const& interface,
     VERIFY_NOT_REACHED();
 }
 
-static void generate_overload_arbiter(SourceGenerator& generator, auto const& overload_set, IDL::Interface const& interface, DeprecatedString const& class_name)
+static void generate_overload_arbiter(SourceGenerator& generator, auto const& overload_set, IDL::Interface const& interface, ByteString const& class_name)
 {
     auto function_generator = generator.fork();
     function_generator.set("class_name", class_name);
@@ -2161,7 +2161,7 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@)
     auto maximum_argument_count = 0u;
     for (auto const& overload : overloads_set)
         maximum_argument_count = max(maximum_argument_count, overload.types.size());
-    function_generator.set("max_argument_count", DeprecatedString::number(maximum_argument_count));
+    function_generator.set("max_argument_count", ByteString::number(maximum_argument_count));
     function_generator.appendln("    switch (min(@max_argument_count@, vm.argument_count())) {");
 
     // Generate the effective overload set for each argument count.
@@ -2182,8 +2182,8 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@)
         if (effective_overload_set.size() > 1)
             distinguishing_argument_index = resolve_distinguishing_argument_index(interface, effective_overload_set, argument_count);
 
-        function_generator.set("current_argument_count", DeprecatedString::number(argument_count));
-        function_generator.set("overload_count", DeprecatedString::number(effective_overload_set.size()));
+        function_generator.set("current_argument_count", ByteString::number(argument_count));
+        function_generator.set("overload_count", ByteString::number(effective_overload_set.size()));
         function_generator.appendln(R"~~~(
     case @current_argument_count@: {
         Vector<IDL::EffectiveOverloadSet::Item> overloads;
@@ -2221,14 +2221,14 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@)
             types_builder.append("}"sv);
             optionality_builder.append("}"sv);
 
-            function_generator.set("overload.callable_id", DeprecatedString::number(overload.callable_id));
-            function_generator.set("overload.types", types_builder.to_deprecated_string());
-            function_generator.set("overload.optionality_values", optionality_builder.to_deprecated_string());
+            function_generator.set("overload.callable_id", ByteString::number(overload.callable_id));
+            function_generator.set("overload.types", types_builder.to_byte_string());
+            function_generator.set("overload.optionality_values", optionality_builder.to_byte_string());
 
             function_generator.appendln("        overloads.empend(@overload.callable_id@, @overload.types@, @overload.optionality_values@);");
         }
 
-        function_generator.set("overload_set.distinguishing_argument_index", DeprecatedString::number(distinguishing_argument_index));
+        function_generator.set("overload_set.distinguishing_argument_index", ByteString::number(distinguishing_argument_index));
         function_generator.append(R"~~~(
         effective_overload_set.emplace(move(overloads), @overload_set.distinguishing_argument_index@);
         break;
@@ -2247,7 +2247,7 @@ JS_DEFINE_NATIVE_FUNCTION(@class_name@::@function.name:snakecase@)
 )~~~");
 
     for (auto i = 0u; i < overload_set.value.size(); ++i) {
-        function_generator.set("overload_id", DeprecatedString::number(i));
+        function_generator.set("overload_id", ByteString::number(i));
         function_generator.append(R"~~~(
     case @overload_id@:
         return @function.name:snakecase@@overload_id@(vm);
@@ -2274,7 +2274,7 @@ static void generate_prototype_or_global_mixin_declarations(IDL::Interface const
         )~~~");
         if (overload_set.value.size() > 1) {
             for (auto i = 0u; i < overload_set.value.size(); ++i) {
-                function_generator.set("overload_suffix", DeprecatedString::number(i));
+                function_generator.set("overload_suffix", ByteString::number(i));
                 function_generator.append(R"~~~(
     JS_DECLARE_NATIVE_FUNCTION(@function.name:snakecase@@overload_suffix@);
 )~~~");
@@ -2420,7 +2420,7 @@ static void collect_attribute_values_of_an_inheritance_stack(SourceGenerator& fu
                 continue;
 
             auto attribute_generator = function_generator.fork();
-            auto return_value_name = DeprecatedString::formatted("{}_retval", attribute.name.to_snakecase());
+            auto return_value_name = ByteString::formatted("{}_retval", attribute.name.to_snakecase());
 
             attribute_generator.set("attribute.name", attribute.name);
             attribute_generator.set("attribute.return_value_name", return_value_name);
@@ -2466,7 +2466,7 @@ static void collect_attribute_values_of_an_inheritance_stack(SourceGenerator& fu
 )~~~");
             }
 
-            generate_wrap_statement(attribute_generator, return_value_name, attribute.type, interface_in_chain, DeprecatedString::formatted("auto {}_wrapped =", return_value_name));
+            generate_wrap_statement(attribute_generator, return_value_name, attribute.type, interface_in_chain, ByteString::formatted("auto {}_wrapped =", return_value_name));
 
             attribute_generator.append(R"~~~(
     MUST(result->create_data_property("@attribute.name@", @attribute.return_value_name@_wrapped));
@@ -2477,7 +2477,7 @@ static void collect_attribute_values_of_an_inheritance_stack(SourceGenerator& fu
             auto constant_generator = function_generator.fork();
             constant_generator.set("constant.name", constant.name);
 
-            generate_wrap_statement(constant_generator, constant.value, constant.type, interface_in_chain, DeprecatedString::formatted("auto constant_{}_value =", constant.name));
+            generate_wrap_statement(constant_generator, constant.value, constant.type, interface_in_chain, ByteString::formatted("auto constant_{}_value =", constant.name));
 
             constant_generator.append(R"~~~(
     MUST(result->create_data_property("@constant.name@", constant_@constant.name@_value));
@@ -2487,7 +2487,7 @@ static void collect_attribute_values_of_an_inheritance_stack(SourceGenerator& fu
 }
 
 // https://webidl.spec.whatwg.org/#default-tojson-steps
-static void generate_default_to_json_function(SourceGenerator& generator, DeprecatedString const& class_name, IDL::Interface const& start_interface)
+static void generate_default_to_json_function(SourceGenerator& generator, ByteString const& class_name, IDL::Interface const& start_interface)
 {
     // NOTE: This is done heavily out of order since the spec mixes parse time and run time type information together.
 
@@ -2526,7 +2526,7 @@ static void generate_named_properties_object_declarations(IDL::Interface const&
 {
     SourceGenerator generator { builder };
 
-    generator.set("named_properties_class", DeprecatedString::formatted("{}Properties", interface.name));
+    generator.set("named_properties_class", ByteString::formatted("{}Properties", interface.name));
 
     generator.append(R"~~~(
 class @named_properties_class@ : public JS::Object {
@@ -2557,7 +2557,7 @@ static void generate_named_properties_object_definitions(IDL::Interface const& i
     generator.set("name", interface.name);
     generator.set("parent_name", interface.parent_name);
     generator.set("prototype_base_class", interface.prototype_base_class);
-    generator.set("named_properties_class", DeprecatedString::formatted("{}Properties", interface.name));
+    generator.set("named_properties_class", ByteString::formatted("{}Properties", interface.name));
 
     // https://webidl.spec.whatwg.org/#create-a-named-properties-object
     generator.append(R"~~~(
@@ -2701,11 +2701,11 @@ static void generate_prototype_or_global_mixin_definitions(IDL::Interface const&
     generator.set("prototype_name", interface.prototype_class); // Used for Global Mixin
 
     if (interface.pair_iterator_types.has_value()) {
-        generator.set("iterator_name", DeprecatedString::formatted("{}Iterator", interface.name));
+        generator.set("iterator_name", ByteString::formatted("{}Iterator", interface.name));
     }
 
     if (is_global_interface) {
-        generator.set("named_properties_class", DeprecatedString::formatted("{}Properties", interface.name));
+        generator.set("named_properties_class", ByteString::formatted("{}Properties", interface.name));
         // Doing this with macros is not super nice, but simplifies codegen a lot.
         generator.append(R"~~~(
 #define define_direct_property (object.define_direct_property)
@@ -2785,7 +2785,7 @@ void @class_name@::initialize(JS::Realm& realm)
         auto constant_generator = generator.fork();
         constant_generator.set("constant.name", constant.name);
 
-        generate_wrap_statement(constant_generator, constant.value, constant.type, interface, DeprecatedString::formatted("auto constant_{}_value =", constant.name));
+        generate_wrap_statement(constant_generator, constant.value, constant.type, interface, ByteString::formatted("auto constant_{}_value =", constant.name));
 
         constant_generator.append(R"~~~(
     define_direct_property("@constant.name@", constant_@constant.name@_value, JS::Attribute::Enumerable);
@@ -2797,7 +2797,7 @@ void @class_name@::initialize(JS::Realm& realm)
         auto function_generator = generator.fork();
         function_generator.set("function.name", overload_set.key);
         function_generator.set("function.name:snakecase", make_input_acceptable_cpp(overload_set.key.to_snakecase()));
-        function_generator.set("function.length", DeprecatedString::number(get_shortest_function_length(overload_set.value)));
+        function_generator.set("function.length", ByteString::number(get_shortest_function_length(overload_set.value)));
 
         // FIXME: What if only some of the overloads are Unscopable?
         if (any_of(overload_set.value, [](auto const& function) { return function.extended_attributes.contains("Unscopable"); })) {
@@ -3351,7 +3351,7 @@ private:
 )~~~");
         if (overload_set.value.size() > 1) {
             for (auto i = 0u; i < overload_set.value.size(); ++i) {
-                function_generator.set("overload_suffix", DeprecatedString::number(i));
+                function_generator.set("overload_suffix", ByteString::number(i));
                 function_generator.append(R"~~~(
     JS_DECLARE_NATIVE_FUNCTION(@function.name:snakecase@@overload_suffix@);
 )~~~");
@@ -3451,7 +3451,7 @@ void @namespace_class@::initialize(JS::Realm& realm)
         auto function_generator = generator.fork();
         function_generator.set("function.name", overload_set.key);
         function_generator.set("function.name:snakecase", make_input_acceptable_cpp(overload_set.key.to_snakecase()));
-        function_generator.set("function.length", DeprecatedString::number(get_shortest_function_length(overload_set.value)));
+        function_generator.set("function.length", ByteString::number(get_shortest_function_length(overload_set.value)));
 
         function_generator.append(R"~~~(
     define_native_function(realm, "@function.name@", @function.name:snakecase@, @function.length@, default_attributes);
@@ -3521,7 +3521,7 @@ private:
 )~~~");
         if (overload_set.value.size() > 1) {
             for (auto i = 0u; i < overload_set.value.size(); ++i) {
-                function_generator.set("overload_suffix", DeprecatedString::number(i));
+                function_generator.set("overload_suffix", ByteString::number(i));
                 function_generator.append(R"~~~(
     JS_DECLARE_NATIVE_FUNCTION(@function.name:snakecase@@overload_suffix@);
 )~~~");
@@ -3694,7 +3694,7 @@ JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Object>> @constructor_class@::constru
             }
         }
 
-        generator.set("constructor.length", DeprecatedString::number(shortest_length));
+        generator.set("constructor.length", ByteString::number(shortest_length));
 
         generator.append(R"~~~(
     auto& vm = this->vm();
@@ -3778,7 +3778,7 @@ JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Object>> @constructor_class@::constru
                     generator.set(".arg_count_suffix", "");
                 } else {
                     generator.set(".bad_arg_count", "JS::ErrorType::BadArgCountMany");
-                    generator.set(".arg_count_suffix", DeprecatedString::formatted(", \"{}\"", shortest_length));
+                    generator.set(".arg_count_suffix", ByteString::formatted(", \"{}\"", shortest_length));
                 }
 
                 generator.append(R"~~~(
@@ -3943,7 +3943,7 @@ void @constructor_class@::initialize(JS::Realm& realm)
         auto constant_generator = generator.fork();
         constant_generator.set("constant.name", constant.name);
 
-        generate_wrap_statement(constant_generator, constant.value, constant.type, interface, DeprecatedString::formatted("auto constant_{}_value =", constant.name));
+        generate_wrap_statement(constant_generator, constant.value, constant.type, interface, ByteString::formatted("auto constant_{}_value =", constant.name));
 
         constant_generator.append(R"~~~(
     define_direct_property("@constant.name@", constant_@constant.name@_value, JS::Attribute::Enumerable);
@@ -3955,7 +3955,7 @@ void @constructor_class@::initialize(JS::Realm& realm)
         auto function_generator = generator.fork();
         function_generator.set("function.name", overload_set.key);
         function_generator.set("function.name:snakecase", make_input_acceptable_cpp(overload_set.key.to_snakecase()));
-        function_generator.set("function.length", DeprecatedString::number(get_shortest_function_length(overload_set.value)));
+        function_generator.set("function.length", ByteString::number(get_shortest_function_length(overload_set.value)));
 
         function_generator.append(R"~~~(
     define_native_function(realm, "@function.name@", @function.name:snakecase@, @function.length@, default_attributes);
@@ -4172,7 +4172,7 @@ void @prototype_class@::initialize(JS::Realm& realm)
     Base::initialize(realm);
 )~~~");
         if (interface.supports_named_properties()) {
-            generator.set("named_properties_class", DeprecatedString::formatted("{}Properties", interface.name));
+            generator.set("named_properties_class", ByteString::formatted("{}Properties", interface.name));
             generator.set("namespaced_name", interface.namespaced_name);
             generator.append(R"~~~(
     define_direct_property(vm().well_known_symbol_to_string_tag(), JS::PrimitiveString::create(vm(), "@namespaced_name@"_string), JS::Attribute::Configurable);
@@ -4198,7 +4198,7 @@ void generate_iterator_prototype_header(IDL::Interface const& interface, StringB
     VERIFY(interface.pair_iterator_types.has_value());
     SourceGenerator generator { builder };
 
-    generator.set("prototype_class", DeprecatedString::formatted("{}IteratorPrototype", interface.name));
+    generator.set("prototype_class", ByteString::formatted("{}IteratorPrototype", interface.name));
 
     generator.append(R"~~~(
 #pragma once
@@ -4228,12 +4228,12 @@ void generate_iterator_prototype_implementation(IDL::Interface const& interface,
     VERIFY(interface.pair_iterator_types.has_value());
     SourceGenerator generator { builder };
 
-    generator.set("name", DeprecatedString::formatted("{}Iterator", interface.name));
+    generator.set("name", ByteString::formatted("{}Iterator", interface.name));
     generator.set("parent_name", interface.parent_name);
-    generator.set("prototype_class", DeprecatedString::formatted("{}IteratorPrototype", interface.name));
+    generator.set("prototype_class", ByteString::formatted("{}IteratorPrototype", interface.name));
     generator.set("prototype_base_class", interface.prototype_base_class);
-    generator.set("fully_qualified_name", DeprecatedString::formatted("{}Iterator", interface.fully_qualified_name));
-    generator.set("possible_include_path", DeprecatedString::formatted("{}Iterator", interface.name.replace("::"sv, "/"sv, ReplaceMode::All)));
+    generator.set("fully_qualified_name", ByteString::formatted("{}Iterator", interface.fully_qualified_name));
+    generator.set("possible_include_path", ByteString::formatted("{}Iterator", interface.name.replace("::"sv, "/"sv, ReplaceMode::All)));
 
     generator.append(R"~~~(
 #include <AK/Function.h>
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/main.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/main.cpp
index 53ce7768382..e09b0004787 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/main.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/main.cpp
@@ -78,7 +78,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         builder.append(namespace_);
         builder.append("::"sv);
         builder.append(interface.name);
-        interface.fully_qualified_name = builder.to_deprecated_string();
+        interface.fully_qualified_name = builder.to_byte_string();
     } else {
         interface.fully_qualified_name = interface.name;
     }
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateAriaRoles.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateAriaRoles.cpp
index c506cb52399..0c6957bc8f2 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateAriaRoles.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateAriaRoles.cpp
@@ -56,8 +56,8 @@ namespace Web::ARIA {
         JsonObject const& value_object = value.as_object();
 
         auto class_definition_generator = generator.fork();
-        class_definition_generator.set("spec_link"sv, value_object.get_deprecated_string("specLink"sv).value());
-        class_definition_generator.set("description"sv, value_object.get_deprecated_string("description"sv).value());
+        class_definition_generator.set("spec_link"sv, value_object.get_byte_string("specLink"sv).value());
+        class_definition_generator.set("description"sv, value_object.get_byte_string("description"sv).value());
         class_definition_generator.set("name"sv, name);
         class_definition_generator.append(R"~~~(
 // @spec_link@
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSEnums.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSEnums.cpp
index 0ee418a7c01..6dff467321f 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSEnums.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSEnums.cpp
@@ -77,7 +77,7 @@ enum class ValueID;
         enum_generator.appendln("enum class @name:titlecase@ : @enum_type@ {");
 
         for (auto& member : members.values()) {
-            auto member_name = member.to_deprecated_string();
+            auto member_name = member.to_byte_string();
             // Don't include aliases in the enum.
             if (member_name.contains('='))
                 continue;
@@ -126,7 +126,7 @@ Optional<@name:titlecase@> value_id_to_@name:snakecase@(ValueID value_id)
 
         for (auto& member : members.values()) {
             auto member_generator = enum_generator.fork();
-            auto member_name = member.to_deprecated_string();
+            auto member_name = member.to_byte_string();
             if (member_name.contains('=')) {
                 auto parts = member_name.split_view('=');
                 member_generator.set("valueid:titlecase", title_casify(parts[0]));
@@ -154,7 +154,7 @@ ValueID to_value_id(@name:titlecase@ @name:snakecase@_value)
 
         for (auto& member : members.values()) {
             auto member_generator = enum_generator.fork();
-            auto member_name = member.to_deprecated_string();
+            auto member_name = member.to_byte_string();
             if (member_name.contains('='))
                 continue;
             member_generator.set("member:titlecase", title_casify(member_name));
@@ -178,7 +178,7 @@ StringView to_string(@name:titlecase@ value)
 
         for (auto& member : members.values()) {
             auto member_generator = enum_generator.fork();
-            auto member_name = member.to_deprecated_string();
+            auto member_name = member.to_byte_string();
             if (member_name.contains('='))
                 continue;
             member_generator.set("member:css", member_name);
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSMathFunctions.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSMathFunctions.cpp
index 0cd2fc5a487..f045518effc 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSMathFunctions.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSMathFunctions.cpp
@@ -182,7 +182,7 @@ OwnPtr<CalculationNode> Parser::parse_math_function(PropertyID property_id, Func
             // Generate some type checks
             VERIFY(parameters.size() == 1);
             auto& parameter_data = parameters[0].as_object();
-            auto parameter_type_string = parameter_data.get_deprecated_string("type"sv).value();
+            auto parameter_type_string = parameter_data.get_byte_string("type"sv).value();
             function_generator.set("type_check", generate_calculation_type_check("argument_type"sv, parameter_type_string));
             function_generator.append(R"~~~(
             if (!(@type_check@)) {
@@ -231,11 +231,11 @@ OwnPtr<CalculationNode> Parser::parse_math_function(PropertyID property_id, Func
             StringView previous_parameter_type_string;
             parameters.for_each([&](JsonValue const& parameter_value) {
                 auto& parameter = parameter_value.as_object();
-                auto parameter_type_string = parameter.get_deprecated_string("type"sv).value();
+                auto parameter_type_string = parameter.get_byte_string("type"sv).value();
                 auto parameter_required = parameter.get_bool("required"sv).value();
 
                 auto parameter_generator = function_generator.fork();
-                parameter_generator.set("parameter_name", parameter.get_deprecated_string("name"sv).value());
+                parameter_generator.set("parameter_name", parameter.get_byte_string("name"sv).value());
                 parameter_generator.set("parameter_index", MUST(String::number(parameter_index)));
 
                 bool parameter_is_calculation;
@@ -245,7 +245,7 @@ OwnPtr<CalculationNode> Parser::parse_math_function(PropertyID property_id, Func
                     parameter_generator.set("parse_function", "parse_rounding_strategy(arguments[argument_index])"_string);
                     parameter_generator.set("check_function", ".has_value()"_string);
                     parameter_generator.set("release_function", ".release_value()"_string);
-                    if (auto default_value = parameter.get_deprecated_string("default"sv); default_value.has_value()) {
+                    if (auto default_value = parameter.get_byte_string("default"sv); default_value.has_value()) {
                         parameter_generator.set("parameter_default", MUST(String::formatted(" = RoundingStrategy::{}", title_casify(default_value.value()))));
                     } else {
                         parameter_generator.set("parameter_default", ""_string);
@@ -260,7 +260,7 @@ OwnPtr<CalculationNode> Parser::parse_math_function(PropertyID property_id, Func
 
                     // NOTE: We have exactly one default value in the data right now, and it's a `<calc-constant>`,
                     //       so that's all we handle.
-                    if (auto default_value = parameter.get_deprecated_string("default"sv); default_value.has_value()) {
+                    if (auto default_value = parameter.get_byte_string("default"sv); default_value.has_value()) {
                         parameter_generator.set("parameter_default", MUST(String::formatted(" = ConstantCalculationNode::create(CalculationNode::constant_type_from_string(\"{}\"sv).value())", default_value.value())));
                     } else {
                         parameter_generator.set("parameter_default", ""_string);
@@ -343,7 +343,7 @@ OwnPtr<CalculationNode> Parser::parse_math_function(PropertyID property_id, Func
             parameter_index = 0;
             parameters.for_each([&](JsonValue const& parameter_value) {
                 auto& parameter = parameter_value.as_object();
-                auto parameter_type_string = parameter.get_deprecated_string("type"sv).value();
+                auto parameter_type_string = parameter.get_byte_string("type"sv).value();
 
                 auto parameter_generator = function_generator.fork();
                 parameter_generator.set("parameter_index"sv, MUST(String::number(parameter_index)));
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSMediaFeatureID.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSMediaFeatureID.cpp
index 870a61d8752..a1991dc3add 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSMediaFeatureID.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSMediaFeatureID.cpp
@@ -140,7 +140,7 @@ bool media_feature_type_is_range(MediaFeatureID media_feature_id)
         auto member_generator = generator.fork();
         member_generator.set("name:titlecase", title_casify(name));
         VERIFY(feature.has("type"sv));
-        auto feature_type = feature.get_deprecated_string("type"sv);
+        auto feature_type = feature.get_byte_string("type"sv);
         VERIFY(feature_type.has_value());
         member_generator.set("is_range", feature_type.value() == "range" ? "true"_string : "false"_string);
         member_generator.append(R"~~~(
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp
index 33ee4bd96a6..0840fdb310d 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPropertyID.cpp
@@ -43,7 +43,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto properties = json.as_object();
 
     // Check we're in alphabetical order
-    DeprecatedString most_recent_name = "";
+    ByteString most_recent_name = "";
     properties.for_each_member([&](auto& name, auto&) {
         if (name < most_recent_name) {
             warnln("`{}` is in the wrong position in `{}`. Please keep this list alphabetical!", name, properties_json_path);
@@ -65,7 +65,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
 void replace_logical_aliases(JsonObject& properties)
 {
-    AK::HashMap<DeprecatedString, DeprecatedString> logical_aliases;
+    AK::HashMap<ByteString, ByteString> logical_aliases;
     properties.for_each_member([&](auto& name, auto& value) {
         VERIFY(value.is_object());
         const auto& value_as_object = value.as_object();
@@ -73,7 +73,7 @@ void replace_logical_aliases(JsonObject& properties)
         if (logical_alias_for.has_value()) {
             auto const& aliased_properties = logical_alias_for.value();
             for (auto const& aliased_property : aliased_properties.values()) {
-                logical_aliases.set(name, aliased_property.to_deprecated_string());
+                logical_aliases.set(name, aliased_property.to_byte_string());
             }
         }
     });
@@ -116,8 +116,8 @@ enum class PropertyID {
     All,
 )~~~");
 
-    Vector<DeprecatedString> shorthand_property_ids;
-    Vector<DeprecatedString> longhand_property_ids;
+    Vector<ByteString> shorthand_property_ids;
+    Vector<ByteString> longhand_property_ids;
 
     properties.for_each_member([&](auto& name, auto& value) {
         VERIFY(value.is_object());
@@ -518,7 +518,7 @@ NonnullRefPtr<StyleValue> property_initial_value(JS::Realm& context_realm, Prope
             dbgln("No initial value specified for property '{}'", name);
             VERIFY_NOT_REACHED();
         }
-        auto initial_value = object.get_deprecated_string("initial"sv);
+        auto initial_value = object.get_byte_string("initial"sv);
         VERIFY(initial_value.has_value());
         auto& initial_value_string = initial_value.value();
 
@@ -739,7 +739,7 @@ Optional<ValueType> property_resolves_percentages_relative_to(PropertyID propert
 
     properties.for_each_member([&](auto& name, auto& value) {
         VERIFY(value.is_object());
-        if (auto resolved_type = value.as_object().get_deprecated_string("percentages-resolve-to"sv); resolved_type.has_value()) {
+        if (auto resolved_type = value.as_object().get_byte_string("percentages-resolve-to"sv); resolved_type.has_value()) {
             auto property_generator = generator.fork();
             property_generator.set("name:titlecase", title_casify(name));
             property_generator.set("resolved_type:titlecase", title_casify(resolved_type.value()));
@@ -768,7 +768,7 @@ size_t property_maximum_value_count(PropertyID property_id)
             VERIFY(max_values.has_value() && max_values->is_number() && !max_values->is_double());
             auto property_generator = generator.fork();
             property_generator.set("name:titlecase", title_casify(name));
-            property_generator.set("max_values", max_values->to_deprecated_string());
+            property_generator.set("max_values", max_values->to_byte_string());
             property_generator.append(R"~~~(
     case PropertyID::@name:titlecase@:
         return @max_values@;
@@ -834,10 +834,10 @@ Vector<PropertyID> longhands_for_shorthand(PropertyID property_id)
                     first = false;
                 else
                     builder.append(", "sv);
-                builder.appendff("PropertyID::{}", title_casify(longhand.to_deprecated_string()));
+                builder.appendff("PropertyID::{}", title_casify(longhand.to_byte_string()));
                 return IterationDecision::Continue;
             });
-            property_generator.set("longhands", builder.to_deprecated_string());
+            property_generator.set("longhands", builder.to_byte_string());
             property_generator.append(R"~~~(
         case PropertyID::@name:titlecase@:
                 return { @longhands@ };
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPseudoClass.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPseudoClass.cpp
index 07efb1468a7..8c1efb07dde 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPseudoClass.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSPseudoClass.cpp
@@ -147,7 +147,7 @@ PseudoClassMetadata pseudo_class_metadata(PseudoClass pseudo_class)
     pseudo_classes_data.for_each_member([&](auto& name, JsonValue const& value) {
         auto member_generator = generator.fork();
         auto& pseudo_class = value.as_object();
-        auto argument_string = pseudo_class.get_deprecated_string("argument"sv).value();
+        auto argument_string = pseudo_class.get_byte_string("argument"sv).value();
 
         bool is_valid_as_identifier = argument_string.is_empty();
         bool is_valid_as_function = !argument_string.is_empty();
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSTransformFunctions.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSTransformFunctions.cpp
index 070c3809f99..e6ca5752f6c 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSTransformFunctions.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSTransformFunctions.cpp
@@ -169,7 +169,7 @@ TransformFunctionMetadata transform_function_metadata(TransformFunction transfor
         JsonArray const& parameters = value.as_object().get_array("parameters"sv).value();
         bool first = true;
         parameters.for_each([&](JsonValue const& value) {
-            GenericLexer lexer { value.as_object().get_deprecated_string("type"sv).value() };
+            GenericLexer lexer { value.as_object().get_byte_string("type"sv).value() };
             VERIFY(lexer.consume_specific('<'));
             auto parameter_type_name = lexer.consume_until('>');
             VERIFY(lexer.consume_specific('>'));
@@ -189,7 +189,7 @@ TransformFunctionMetadata transform_function_metadata(TransformFunction transfor
             member_generator.append(first ? " "sv : ", "sv);
             first = false;
 
-            member_generator.append(MUST(String::formatted("{{ TransformFunctionParameterType::{}, {}}}", parameter_type, value.as_object().get("required"sv)->to_deprecated_string())));
+            member_generator.append(MUST(String::formatted("{{ TransformFunctionParameterType::{}, {}}}", parameter_type, value.as_object().get("required"sv)->to_byte_string())));
         });
 
         member_generator.append(R"~~~( }
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSValueID.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSValueID.cpp
index bc3d65ea965..d2243992d76 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSValueID.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateCSSValueID.cpp
@@ -57,7 +57,7 @@ enum class ValueID {
 
     identifier_data.for_each([&](auto& name) {
         auto member_generator = generator.fork();
-        member_generator.set("name:titlecase", title_casify(name.to_deprecated_string()));
+        member_generator.set("name:titlecase", title_casify(name.to_byte_string()));
 
         member_generator.append(R"~~~(
     @name:titlecase@,
@@ -105,8 +105,8 @@ HashMap<StringView, ValueID, AK::CaseInsensitiveASCIIStringViewTraits> g_stringv
 
     identifier_data.for_each([&](auto& name) {
         auto member_generator = generator.fork();
-        member_generator.set("name", name.to_deprecated_string());
-        member_generator.set("name:titlecase", title_casify(name.to_deprecated_string()));
+        member_generator.set("name", name.to_byte_string());
+        member_generator.set("name:titlecase", title_casify(name.to_byte_string()));
         member_generator.append(R"~~~(
     {"@name@"sv, ValueID::@name:titlecase@},
 )~~~");
@@ -126,8 +126,8 @@ StringView string_from_value_id(ValueID value_id) {
 
     identifier_data.for_each([&](auto& name) {
         auto member_generator = generator.fork();
-        member_generator.set("name", name.to_deprecated_string());
-        member_generator.set("name:titlecase", title_casify(name.to_deprecated_string()));
+        member_generator.set("name", name.to_byte_string());
+        member_generator.set("name:titlecase", title_casify(name.to_byte_string()));
         member_generator.append(R"~~~(
     case ValueID::@name:titlecase@:
         return "@name@"sv;
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
index 9e4b826997f..0c9552ad3fe 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/SourceGenerator.h>
 #include <AK/StringBuilder.h>
@@ -15,11 +15,11 @@
 #include <LibMain/Main.h>
 
 static ErrorOr<void> add_to_interface_sets(IDL::Interface&, Vector<IDL::Interface&>& intrinsics, Vector<IDL::Interface&>& window_exposed, Vector<IDL::Interface&>& dedicated_worker_exposed, Vector<IDL::Interface&>& shared_worker_exposed);
-static DeprecatedString s_error_string;
+static ByteString s_error_string;
 
 struct LegacyConstructor {
-    DeprecatedString name;
-    DeprecatedString constructor_class;
+    ByteString name;
+    ByteString constructor_class;
 };
 
 static void consume_whitespace(GenericLexer& lexer)
@@ -52,7 +52,7 @@ static Optional<LegacyConstructor> const& lookup_legacy_constructor(IDL::Interfa
     consume_whitespace(function_lexer);
 
     auto name = function_lexer.consume_until([](auto ch) { return is_ascii_space(ch) || ch == '('; });
-    auto constructor_class = DeprecatedString::formatted("{}Constructor", name);
+    auto constructor_class = ByteString::formatted("{}Constructor", name);
 
     s_legacy_constructors.set(interface.name, LegacyConstructor { name, move(constructor_class) });
     return s_legacy_constructors.get(interface.name).value();
@@ -264,7 +264,7 @@ static ErrorOr<void> generate_exposed_interface_header(StringView class_name, St
     StringBuilder builder;
     SourceGenerator generator(builder);
 
-    generator.set("global_object_snake_name", DeprecatedString(class_name).to_snakecase());
+    generator.set("global_object_snake_name", ByteString(class_name).to_snakecase());
     generator.append(R"~~~(
 #pragma once
 
@@ -278,7 +278,7 @@ void add_@global_object_snake_name@_exposed_interfaces(JS::Object&);
 
 )~~~");
 
-    auto generated_header_path = LexicalPath(output_path).append(DeprecatedString::formatted("{}ExposedInterfaces.h", class_name)).string();
+    auto generated_header_path = LexicalPath(output_path).append(ByteString::formatted("{}ExposedInterfaces.h", class_name)).string();
     auto generated_header_file = TRY(Core::File::open(generated_header_path, Core::File::OpenMode::Write));
     TRY(generated_header_file->write_until_depleted(generator.as_string_view().bytes()));
 
@@ -291,7 +291,7 @@ static ErrorOr<void> generate_exposed_interface_implementation(StringView class_
     SourceGenerator generator(builder);
 
     generator.set("global_object_name", class_name);
-    generator.set("global_object_snake_name", DeprecatedString(class_name).to_snakecase());
+    generator.set("global_object_snake_name", ByteString(class_name).to_snakecase());
 
     generator.append(R"~~~(
 #include <LibJS/Runtime/Object.h>
@@ -366,7 +366,7 @@ void add_@global_object_snake_name@_exposed_interfaces(JS::Object& global)
 }
 )~~~");
 
-    auto generated_implementation_path = LexicalPath(output_path).append(DeprecatedString::formatted("{}ExposedInterfaces.cpp", class_name)).string();
+    auto generated_implementation_path = LexicalPath(output_path).append(ByteString::formatted("{}ExposedInterfaces.cpp", class_name)).string();
     auto generated_implementation_file = TRY(Core::File::open(generated_implementation_path, Core::File::OpenMode::Write));
     TRY(generated_implementation_file->write_until_depleted(generator.as_string_view().bytes()));
 
@@ -379,7 +379,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     StringView output_path;
     StringView base_path;
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
 
     args_parser.add_option(output_path, "Path to output generated files into", "output-path", 'o', "output-path");
     args_parser.add_option(base_path, "Path to root of IDL file tree", "base-path", 'b', "base-path");
@@ -392,16 +392,16 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     const LexicalPath lexical_base(base_path);
 
     // Read in all IDL files, we must own the storage for all of these for the lifetime of the program
-    Vector<DeprecatedString> file_contents;
-    for (DeprecatedString const& path : paths) {
+    Vector<ByteString> file_contents;
+    for (ByteString const& path : paths) {
         auto file_or_error = Core::File::open(path, Core::File::OpenMode::Read);
         if (file_or_error.is_error()) {
-            s_error_string = DeprecatedString::formatted("Unable to open file {}", path);
+            s_error_string = ByteString::formatted("Unable to open file {}", path);
             return Error::from_string_view(s_error_string.view());
         }
         auto file = file_or_error.release_value();
         auto string = MUST(file->read_until_eof());
-        file_contents.append(DeprecatedString(ReadonlyBytes(string)));
+        file_contents.append(ByteString(ReadonlyBytes(string)));
     }
     VERIFY(paths.size() == file_contents.size());
 
@@ -453,7 +453,7 @@ static ErrorOr<ExposedTo> parse_exposure_set(IDL::Interface& interface)
 
     auto maybe_exposed = interface.extended_attributes.get("Exposed");
     if (!maybe_exposed.has_value()) {
-        s_error_string = DeprecatedString::formatted("Interface {} is missing extended attribute Exposed", interface.name);
+        s_error_string = ByteString::formatted("Interface {} is missing extended attribute Exposed", interface.name);
         return Error::from_string_view(s_error_string.view());
     }
     auto exposed = maybe_exposed.value().trim_whitespace();
@@ -485,18 +485,18 @@ static ErrorOr<ExposedTo> parse_exposure_set(IDL::Interface& interface)
             } else if (candidate == "AudioWorklet"sv) {
                 whom |= ExposedTo::AudioWorklet;
             } else {
-                s_error_string = DeprecatedString::formatted("Unknown Exposed attribute candidate {} in {} in {}", candidate, exposed, interface.name);
+                s_error_string = ByteString::formatted("Unknown Exposed attribute candidate {} in {} in {}", candidate, exposed, interface.name);
                 return Error::from_string_view(s_error_string.view());
             }
         }
         if (whom == ExposedTo::Nobody) {
-            s_error_string = DeprecatedString::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
+            s_error_string = ByteString::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
             return Error::from_string_view(s_error_string.view());
         }
         return whom;
     }
 
-    s_error_string = DeprecatedString::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
+    s_error_string = ByteString::formatted("Unknown Exposed attribute {} in {}", exposed, interface.name);
     return Error::from_string_view(s_error_string.view());
 }
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GeneratorUtil.h b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GeneratorUtil.h
index 3cf1c7acfbf..28c1b77d31f 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GeneratorUtil.h
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GeneratorUtil.h
@@ -52,7 +52,7 @@ String camel_casify(StringView dashy_name)
 String snake_casify(StringView dashy_name)
 {
     // FIXME: We don't really need to convert dashy_name to a String first, but currently
-    //        all the `replace` functions that take a StringView return DeprecatedString.
+    //        all the `replace` functions that take a StringView return ByteString.
     return MUST(MUST(String::from_utf8(dashy_name)).replace("-"sv, "_"sv, ReplaceMode::All));
 }
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/StateMachineGenerator/main.cpp b/Meta/Lagom/Tools/CodeGenerators/StateMachineGenerator/main.cpp
index dac4f4d44ad..507c7f40ed9 100644
--- a/Meta/Lagom/Tools/CodeGenerators/StateMachineGenerator/main.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/StateMachineGenerator/main.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/GenericLexer.h>
 #include <AK/HashTable.h>
 #include <AK/OwnPtr.h>
@@ -22,8 +22,8 @@ struct Range {
 };
 
 struct StateTransition {
-    Optional<DeprecatedString> new_state;
-    Optional<DeprecatedString> action;
+    Optional<ByteString> new_state;
+    Optional<ByteString> action;
 };
 
 struct MatchedAction {
@@ -32,18 +32,18 @@ struct MatchedAction {
 };
 
 struct State {
-    DeprecatedString name;
+    ByteString name;
     Vector<MatchedAction> actions;
-    Optional<DeprecatedString> entry_action;
-    Optional<DeprecatedString> exit_action;
+    Optional<ByteString> entry_action;
+    Optional<ByteString> exit_action;
 };
 
 struct StateMachine {
-    DeprecatedString name;
-    DeprecatedString initial_state;
+    ByteString name;
+    ByteString initial_state;
     Vector<State> states;
     Optional<State> anywhere;
-    Optional<DeprecatedString> namespaces;
+    Optional<ByteString> namespaces;
 };
 
 static OwnPtr<StateMachine>
@@ -159,7 +159,7 @@ parse_state_machine(StringView input)
                       consume_whitespace();
                       state.exit_action = consume_identifier();
                   } else if (lexer.next_is('@')) {
-                      auto directive = consume_identifier().to_deprecated_string();
+                      auto directive = consume_identifier().to_byte_string();
                       fprintf(stderr, "Unimplemented @ directive %s\n", directive.characters());
                       exit(1);
                   } else {
@@ -189,7 +189,7 @@ parse_state_machine(StringView input)
             lexer.consume_specific('@');
             state_machine->anywhere = consume_state_description();
         } else if (lexer.consume_specific('@')) {
-            auto directive = consume_identifier().to_deprecated_string();
+            auto directive = consume_identifier().to_byte_string();
             fprintf(stderr, "Unimplemented @ directive %s\n", directive.characters());
             exit(1);
         } else {
@@ -238,9 +238,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     return 0;
 }
 
-HashTable<DeprecatedString> actions(StateMachine const& machine)
+HashTable<ByteString> actions(StateMachine const& machine)
 {
-    HashTable<DeprecatedString> table;
+    HashTable<ByteString> table;
 
     auto do_state = [&](State const& state) {
         if (state.entry_action.has_value())
@@ -302,7 +302,7 @@ void output_header(StateMachine const& machine, SourceGenerator& generator)
 {
     generator.set("class_name", machine.name);
     generator.set("initial_state", machine.initial_state);
-    generator.set("state_count", DeprecatedString::number(machine.states.size() + 1));
+    generator.set("state_count", ByteString::number(machine.states.size() + 1));
 
     generator.append(R"~~~(
 #pragma once
diff --git a/Meta/Lagom/Tools/ConfigureComponents/main.cpp b/Meta/Lagom/Tools/ConfigureComponents/main.cpp
index bb2e8d3e844..b280484a996 100644
--- a/Meta/Lagom/Tools/ConfigureComponents/main.cpp
+++ b/Meta/Lagom/Tools/ConfigureComponents/main.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/LexicalPath.h>
 #include <AK/QuickSort.h>
@@ -25,18 +25,18 @@ enum class ComponentCategory {
 };
 
 struct ComponentData {
-    DeprecatedString name;
-    DeprecatedString description;
+    ByteString name;
+    ByteString description;
     ComponentCategory category { ComponentCategory::Optional };
     bool was_selected { false };
-    Vector<DeprecatedString> dependencies;
+    Vector<ByteString> dependencies;
     bool is_selected { false };
 };
 
 struct WhiptailOption {
-    DeprecatedString tag;
-    DeprecatedString name;
-    DeprecatedString description;
+    ByteString tag;
+    ByteString name;
+    ByteString description;
     bool checked { false };
 };
 
@@ -77,7 +77,7 @@ static Vector<ComponentData> read_component_data(Core::ConfigFile const& config_
     return components;
 }
 
-static Result<Vector<DeprecatedString>, int> run_whiptail(WhiptailMode mode, Vector<WhiptailOption> const& options, StringView title, StringView description)
+static Result<Vector<ByteString>, int> run_whiptail(WhiptailMode mode, Vector<WhiptailOption> const& options, StringView title, StringView description)
 {
     struct winsize w;
     if (ioctl(0, TIOCGWINSZ, &w) < 0) {
@@ -97,7 +97,7 @@ static Result<Vector<DeprecatedString>, int> run_whiptail(WhiptailMode mode, Vec
     int read_fd = pipefd[0];
     int write_fd = pipefd[1];
 
-    Vector<DeprecatedString> arguments = { "whiptail", "--notags", "--separate-output", "--output-fd", DeprecatedString::number(write_fd) };
+    Vector<ByteString> arguments = { "whiptail", "--notags", "--separate-output", "--output-fd", ByteString::number(write_fd) };
 
     if (!title.is_empty()) {
         arguments.append("--title");
@@ -116,13 +116,13 @@ static Result<Vector<DeprecatedString>, int> run_whiptail(WhiptailMode mode, Vec
     }
 
     if (description.is_empty())
-        arguments.append(DeprecatedString::empty());
+        arguments.append(ByteString::empty());
     else
-        arguments.append(DeprecatedString::formatted("\n {}", description));
+        arguments.append(ByteString::formatted("\n {}", description));
 
-    arguments.append(DeprecatedString::number(height));
-    arguments.append(DeprecatedString::number(width));
-    arguments.append(DeprecatedString::number(height - 9));
+    arguments.append(ByteString::number(height));
+    arguments.append(ByteString::number(width));
+    arguments.append(ByteString::number(height - 9));
 
     // Check how wide the name field needs to be.
     size_t max_name_width = 0;
@@ -133,7 +133,7 @@ static Result<Vector<DeprecatedString>, int> run_whiptail(WhiptailMode mode, Vec
 
     for (auto& option : options) {
         arguments.append(option.tag);
-        arguments.append(DeprecatedString::formatted("{:{2}}    {}", option.name, option.description, max_name_width));
+        arguments.append(ByteString::formatted("{:{2}}    {}", option.name, option.description, max_name_width));
         if (mode == WhiptailMode::Checklist)
             arguments.append(option.checked ? "1" : "0");
     }
@@ -151,7 +151,7 @@ static Result<Vector<DeprecatedString>, int> run_whiptail(WhiptailMode mode, Vec
         return -1;
     }
 
-    auto full_term_variable = DeprecatedString::formatted("TERM={}", term_variable);
+    auto full_term_variable = ByteString::formatted("TERM={}", term_variable);
     auto colors = "NEWT_COLORS=root=,black\ncheckbox=black,lightgray";
 
     char* env[3];
@@ -202,10 +202,10 @@ static Result<Vector<DeprecatedString>, int> run_whiptail(WhiptailMode mode, Vec
         warnln("\e[31mError:\e[0m Could not read data from file descriptor: {}", data_or_error.error());
         return -1;
     }
-    return DeprecatedString::copy(data_or_error.value()).split('\n');
+    return ByteString::copy(data_or_error.value()).split('\n');
 }
 
-static bool run_system_command(DeprecatedString const& command, StringView command_name)
+static bool run_system_command(ByteString const& command, StringView command_name)
 {
     if (command.starts_with("cmake"sv))
         warnln("\e[34mRunning CMake...\e[0m");
@@ -234,7 +234,7 @@ int main()
     auto current_working_directory = FileSystem::current_working_directory();
     if (current_working_directory.is_error())
         return 1;
-    auto lexical_cwd = LexicalPath(current_working_directory.release_value().to_deprecated_string());
+    auto lexical_cwd = LexicalPath(current_working_directory.release_value().to_byte_string());
     auto& parts = lexical_cwd.parts_view();
     if (parts.size() < 2 || parts[parts.size() - 2] != "Build") {
         warnln("\e[31mError:\e[0m This program needs to be executed from inside 'Build/*'.");
@@ -281,7 +281,7 @@ int main()
     StringView build_type = customize ? type.substring_view(7) : type.view();
 
     // Step 4: Customize the configuration if the user requested to. In any case, set the components component.is_selected value correctly.
-    Vector<DeprecatedString> activated_components;
+    Vector<ByteString> activated_components;
 
     if (customize) {
         Vector<WhiptailOption> options;
@@ -297,7 +297,7 @@ int main()
             }
 
             // NOTE: Required components will always be preselected.
-            WhiptailOption option { component.name, component.name, description_builder.to_deprecated_string(), is_required };
+            WhiptailOption option { component.name, component.name, description_builder.to_byte_string(), is_required };
             if (build_type == "REQUIRED") {
                 // noop
             } else if (build_type == "RECOMMENDED") {
@@ -343,13 +343,13 @@ int main()
     }
 
     // Step 5: Generate the cmake command.
-    Vector<DeprecatedString> cmake_arguments = { "cmake", "../..", "-G", "Ninja", "-DBUILD_EVERYTHING=OFF" };
+    Vector<ByteString> cmake_arguments = { "cmake", "../..", "-G", "Ninja", "-DBUILD_EVERYTHING=OFF" };
     for (auto& component : components)
-        cmake_arguments.append(DeprecatedString::formatted("-DBUILD_{}={}", component.name.to_uppercase(), component.is_selected ? "ON" : "OFF"));
+        cmake_arguments.append(ByteString::formatted("-DBUILD_{}={}", component.name.to_uppercase(), component.is_selected ? "ON" : "OFF"));
 
     warnln("\e[34mThe following command will be run:\e[0m");
     outln("ninja clean \\\n  && rm -rf Root \\");
-    outln("  && {}", DeprecatedString::join(' ', cmake_arguments));
+    outln("  && {}", ByteString::join(' ', cmake_arguments));
     warn("\e[34mDo you want to run the command?\e[0m [Y/n] ");
     auto character = getchar();
     if (character == 'n' || character == 'N') {
@@ -358,7 +358,7 @@ int main()
     }
 
     // Step 6: Run 'ninja clean', 'rm -rf Root' and CMake
-    auto command = DeprecatedString::join(' ', cmake_arguments);
+    auto command = ByteString::join(' ', cmake_arguments);
     if (!run_system_command("ninja clean"sv, "Ninja"sv))
         return 1;
     if (!run_system_command("rm -rf Root"sv, "rm"sv))
diff --git a/Meta/Lagom/Tools/IPCMagicLinter/main.cpp b/Meta/Lagom/Tools/IPCMagicLinter/main.cpp
index e79937ee416..19e0666e386 100644
--- a/Meta/Lagom/Tools/IPCMagicLinter/main.cpp
+++ b/Meta/Lagom/Tools/IPCMagicLinter/main.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/StringView.h>
 #include <AK/Vector.h>
@@ -23,7 +23,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
 
     // Read files, compute their hashes, ignore collisions for now.
-    HashMap<u32, Vector<DeprecatedString>> inverse_hashes;
+    HashMap<u32, Vector<ByteString>> inverse_hashes;
     bool had_errors = false;
     for (auto filename : arguments.strings.slice(1)) {
 
@@ -42,7 +42,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         auto file = file_or_error.release_value();
 
-        DeprecatedString endpoint_name;
+        ByteString endpoint_name;
 
         auto const read_lines = [&]() -> ErrorOr<void> {
             while (TRY(file->can_read_line())) {
diff --git a/Meta/Lagom/Wasm/js_repl.cpp b/Meta/Lagom/Wasm/js_repl.cpp
index ed5c78a7e9a..0eab1a3f62d 100644
--- a/Meta/Lagom/Wasm/js_repl.cpp
+++ b/Meta/Lagom/Wasm/js_repl.cpp
@@ -49,7 +49,7 @@ EM_JS(void, user_display, (char const* string, u32 length), { globalDisplayToUse
 template<typename... Args>
 void display(CheckedFormatString<Args...> format_string, Args const&... args)
 {
-    auto string = DeprecatedString::formatted(format_string.view(), args...);
+    auto string = ByteString::formatted(format_string.view(), args...);
     user_display(string.characters(), string.length());
 }
 
@@ -247,7 +247,7 @@ public:
     // 2.3. Printer(logLevel, args[, options]), https://console.spec.whatwg.org/#printer
     virtual JS::ThrowCompletionOr<JS::Value> printer(JS::Console::LogLevel log_level, PrinterArguments arguments) override
     {
-        DeprecatedString indent = DeprecatedString::repeated("  "sv, m_group_stack_depth);
+        ByteString indent = ByteString::repeated("  "sv, m_group_stack_depth);
 
         if (log_level == JS::Console::LogLevel::Trace) {
             auto trace = arguments.get<JS::Console::Trace>();
@@ -269,7 +269,7 @@ public:
             return JS::js_undefined();
         }
 
-        auto output = DeprecatedString::join(' ', arguments.get<JS::MarkedVector<JS::Value>>());
+        auto output = ByteString::join(' ', arguments.get<JS::MarkedVector<JS::Value>>());
         switch (log_level) {
         case JS::Console::LogLevel::Debug:
             displayln("{}{}", indent, output);
diff --git a/Meta/gn/secondary/AK/BUILD.gn b/Meta/gn/secondary/AK/BUILD.gn
index 6e2cfdffc12..94986927c29 100644
--- a/Meta/gn/secondary/AK/BUILD.gn
+++ b/Meta/gn/secondary/AK/BUILD.gn
@@ -35,6 +35,7 @@ source_set("AK") {
     "BumpAllocator.h",
     "ByteBuffer.h",
     "ByteReader.h",
+    "ByteString.h",
     "CharacterTypes.h",
     "Checked.h",
     "CheckedFormatString.h",
@@ -50,7 +51,6 @@ source_set("AK") {
     "DefaultDelete.h",
     "Demangle.h",
     "DeprecatedFlyString.h",
-    "DeprecatedString.h",
     "Diagnostics.h",
     "DisjointChunks.h",
     "DistinctNumeric.h",
@@ -189,12 +189,12 @@ source_set("sources") {
   sources = [
     "Assertions.cpp",
     "Base64.cpp",
+    "ByteString.cpp",
     "CircularBuffer.cpp",
     "ConstrainedStream.cpp",
     "CountingStream.cpp",
     "DOSPackedTime.cpp",
     "DeprecatedFlyString.cpp",
-    "DeprecatedString.cpp",
     "Error.cpp",
     "FloatingPointStringConversions.cpp",
     "FlyString.cpp",
diff --git a/Meta/serenity_gdb.py b/Meta/serenity_gdb.py
index 028f85e3342..9be85ec2465 100644
--- a/Meta/serenity_gdb.py
+++ b/Meta/serenity_gdb.py
@@ -38,7 +38,7 @@ def handler_class_for_type(type, re=re.compile('^([^<]+)(<.*>)?$')):
         return AKSinglyLinkedList
     elif klass == 'AK::String':
         return AKString
-    elif klass == 'AK::DeprecatedString':
+    elif klass == 'AK::ByteString':
         return AKDeprecatedString
     elif klass == 'AK::StringView':
         return AKStringView
@@ -178,7 +178,7 @@ class AKDeprecatedString:
 
     @classmethod
     def prettyprint_type(cls, type):
-        return 'AK::DeprecatedString'
+        return 'AK::ByteString'
 
 
 class AKStringView:
diff --git a/Ports/OpenJDK/patches/0008-java.base-Enable-java.lang.Process-on-serenity.patch b/Ports/OpenJDK/patches/0008-java.base-Enable-java.lang.Process-on-serenity.patch
index 0051447a62e..69c80866a5e 100644
--- a/Ports/OpenJDK/patches/0008-java.base-Enable-java.lang.Process-on-serenity.patch
+++ b/Ports/OpenJDK/patches/0008-java.base-Enable-java.lang.Process-on-serenity.patch
@@ -187,7 +187,7 @@ index 0000000000000000000000000000000000000000..9f4410816af68b2a1912255807fbbe4b
 +    unix_getUserInfo(env, jinfo, proc.pid);
 +    JNU_CHECK_EXCEPTION(env);
 +
-+    auto cmdline_file = JAVA_TRY(Core::File::open(DeprecatedString::formatted("/proc/{}/cmdline", pid), Core::File::OpenMode::Read), "Unable to open /proc/pid/cmdline"sv);
++    auto cmdline_file = JAVA_TRY(Core::File::open(ByteString::formatted("/proc/{}/cmdline", pid), Core::File::OpenMode::Read), "Unable to open /proc/pid/cmdline"sv);
 +    auto contents = JAVA_TRY(cmdline_file->read_until_eof(), "Unable to read /proc/pid/cmdline"sv);
 +    auto cmdline = JAVA_TRY(JsonValue::from_string(contents), "Invalid JSON in /proc/pid/cmdline"sv);
 +
diff --git a/Tests/AK/CMakeLists.txt b/Tests/AK/CMakeLists.txt
index 02dcc4ebb9d..8ccab64845e 100644
--- a/Tests/AK/CMakeLists.txt
+++ b/Tests/AK/CMakeLists.txt
@@ -13,13 +13,13 @@ set(AK_TEST_SOURCES
     TestBitStream.cpp
     TestBuiltinWrappers.cpp
     TestByteBuffer.cpp
+    TestByteString.cpp
     TestCharacterTypes.cpp
     TestChecked.cpp
     TestCircularBuffer.cpp
     TestCircularDeque.cpp
     TestCircularQueue.cpp
     TestComplex.cpp
-    TestDeprecatedString.cpp
     TestDisjointChunks.cpp
     TestDistinctNumeric.cpp
     TestDoublyLinkedList.cpp
diff --git a/Tests/AK/TestBase64.cpp b/Tests/AK/TestBase64.cpp
index f4b3d114972..02539a60612 100644
--- a/Tests/AK/TestBase64.cpp
+++ b/Tests/AK/TestBase64.cpp
@@ -7,14 +7,14 @@
 #include <LibTest/TestCase.h>
 
 #include <AK/Base64.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <string.h>
 
 TEST_CASE(test_decode)
 {
     auto decode_equal = [&](StringView input, StringView expected) {
         auto decoded = TRY_OR_FAIL(decode_base64(input));
-        EXPECT(DeprecatedString::copy(decoded) == expected);
+        EXPECT(ByteString::copy(decoded) == expected);
         EXPECT(expected.length() <= calculate_base64_decoded_length(input.bytes()));
     };
 
diff --git a/Tests/AK/TestBinaryHeap.cpp b/Tests/AK/TestBinaryHeap.cpp
index 8388c48d566..6b21590a2d8 100644
--- a/Tests/AK/TestBinaryHeap.cpp
+++ b/Tests/AK/TestBinaryHeap.cpp
@@ -7,7 +7,7 @@
 #include <LibTest/TestCase.h>
 
 #include <AK/BinaryHeap.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 
 using namespace Test::Randomized;
 
@@ -46,7 +46,7 @@ TEST_CASE(populate_int)
 
 TEST_CASE(populate_string)
 {
-    BinaryHeap<int, DeprecatedString, 5> strings;
+    BinaryHeap<int, ByteString, 5> strings;
     strings.insert(1, "ABC");
     strings.insert(2, "DEF");
     EXPECT_EQ(strings.size(), 2u);
diff --git a/Tests/AK/TestBinarySearch.cpp b/Tests/AK/TestBinarySearch.cpp
index 4c16f67d279..4f41ac260fe 100644
--- a/Tests/AK/TestBinarySearch.cpp
+++ b/Tests/AK/TestBinarySearch.cpp
@@ -51,20 +51,20 @@ TEST_CASE(array_doubles)
 
 TEST_CASE(vector_strings)
 {
-    Vector<DeprecatedString> strings;
+    Vector<ByteString> strings;
     strings.append("bat");
     strings.append("cat");
     strings.append("dog");
 
-    auto string_compare = [](DeprecatedString const& a, DeprecatedString const& b) -> int {
+    auto string_compare = [](ByteString const& a, ByteString const& b) -> int {
         return strcmp(a.characters(), b.characters());
     };
-    auto test1 = *binary_search(strings, DeprecatedString("bat"), nullptr, string_compare);
-    auto test2 = *binary_search(strings, DeprecatedString("cat"), nullptr, string_compare);
-    auto test3 = *binary_search(strings, DeprecatedString("dog"), nullptr, string_compare);
-    EXPECT_EQ(test1, DeprecatedString("bat"));
-    EXPECT_EQ(test2, DeprecatedString("cat"));
-    EXPECT_EQ(test3, DeprecatedString("dog"));
+    auto test1 = *binary_search(strings, ByteString("bat"), nullptr, string_compare);
+    auto test2 = *binary_search(strings, ByteString("cat"), nullptr, string_compare);
+    auto test3 = *binary_search(strings, ByteString("dog"), nullptr, string_compare);
+    EXPECT_EQ(test1, ByteString("bat"));
+    EXPECT_EQ(test2, ByteString("cat"));
+    EXPECT_EQ(test3, ByteString("dog"));
 }
 
 TEST_CASE(single_element)
diff --git a/Tests/AK/TestDeprecatedString.cpp b/Tests/AK/TestByteString.cpp
similarity index 62%
rename from Tests/AK/TestDeprecatedString.cpp
rename to Tests/AK/TestByteString.cpp
index 1add9f16405..2f115a1704f 100644
--- a/Tests/AK/TestDeprecatedString.cpp
+++ b/Tests/AK/TestByteString.cpp
@@ -6,26 +6,26 @@
 
 #include <LibTest/TestCase.h>
 
+#include <AK/ByteString.h>
 #include <AK/DeprecatedFlyString.h>
-#include <AK/DeprecatedString.h>
 #include <AK/StringBuilder.h>
 #include <AK/Vector.h>
 #include <cstring>
 
 TEST_CASE(construct_empty)
 {
-    EXPECT(DeprecatedString().is_empty());
-    EXPECT(DeprecatedString().characters() != nullptr);
+    EXPECT(ByteString().is_empty());
+    EXPECT(ByteString().characters() != nullptr);
 
-    EXPECT(DeprecatedString("").is_empty());
-    EXPECT(DeprecatedString("").characters() != nullptr);
+    EXPECT(ByteString("").is_empty());
+    EXPECT(ByteString("").characters() != nullptr);
 
-    EXPECT(DeprecatedString("").impl() == DeprecatedString::empty().impl());
+    EXPECT(ByteString("").impl() == ByteString::empty().impl());
 }
 
 TEST_CASE(construct_contents)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     EXPECT(!test_string.is_empty());
     EXPECT_EQ(test_string.length(), 6u);
     EXPECT_EQ(test_string.length(), strlen(test_string.characters()));
@@ -39,45 +39,45 @@ TEST_CASE(construct_contents)
 
 TEST_CASE(equal)
 {
-    EXPECT_EQ(DeprecatedString::empty(), DeprecatedString {});
+    EXPECT_EQ(ByteString::empty(), ByteString {});
 }
 
 TEST_CASE(compare)
 {
-    EXPECT("a"sv < DeprecatedString("b"));
-    EXPECT(!("a"sv > DeprecatedString("b")));
-    EXPECT("b"sv > DeprecatedString("a"));
-    EXPECT(!("b"sv < DeprecatedString("b")));
-    EXPECT("a"sv >= DeprecatedString("a"));
-    EXPECT(!("a"sv >= DeprecatedString("b")));
-    EXPECT("a"sv <= DeprecatedString("a"));
-    EXPECT(!("b"sv <= DeprecatedString("a")));
+    EXPECT("a"sv < ByteString("b"));
+    EXPECT(!("a"sv > ByteString("b")));
+    EXPECT("b"sv > ByteString("a"));
+    EXPECT(!("b"sv < ByteString("b")));
+    EXPECT("a"sv >= ByteString("a"));
+    EXPECT(!("a"sv >= ByteString("b")));
+    EXPECT("a"sv <= ByteString("a"));
+    EXPECT(!("b"sv <= ByteString("a")));
 
-    EXPECT(DeprecatedString("a") > DeprecatedString());
-    EXPECT(!(DeprecatedString() > DeprecatedString("a")));
-    EXPECT(DeprecatedString() < DeprecatedString("a"));
-    EXPECT(!(DeprecatedString("a") < DeprecatedString()));
-    EXPECT(DeprecatedString("a") >= DeprecatedString());
-    EXPECT(!(DeprecatedString() >= DeprecatedString("a")));
-    EXPECT(DeprecatedString() <= DeprecatedString("a"));
-    EXPECT(!(DeprecatedString("a") <= DeprecatedString()));
+    EXPECT(ByteString("a") > ByteString());
+    EXPECT(!(ByteString() > ByteString("a")));
+    EXPECT(ByteString() < ByteString("a"));
+    EXPECT(!(ByteString("a") < ByteString()));
+    EXPECT(ByteString("a") >= ByteString());
+    EXPECT(!(ByteString() >= ByteString("a")));
+    EXPECT(ByteString() <= ByteString("a"));
+    EXPECT(!(ByteString("a") <= ByteString()));
 
-    EXPECT(!(DeprecatedString() > DeprecatedString()));
-    EXPECT(!(DeprecatedString() < DeprecatedString()));
-    EXPECT(DeprecatedString() >= DeprecatedString());
-    EXPECT(DeprecatedString() <= DeprecatedString());
+    EXPECT(!(ByteString() > ByteString()));
+    EXPECT(!(ByteString() < ByteString()));
+    EXPECT(ByteString() >= ByteString());
+    EXPECT(ByteString() <= ByteString());
 }
 
 TEST_CASE(index_access)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     EXPECT_EQ(test_string[0], 'A');
     EXPECT_EQ(test_string[1], 'B');
 }
 
 TEST_CASE(starts_with)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     EXPECT(test_string.starts_with("AB"sv));
     EXPECT(test_string.starts_with('A'));
     EXPECT(!test_string.starts_with('B'));
@@ -89,7 +89,7 @@ TEST_CASE(starts_with)
 
 TEST_CASE(ends_with)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     EXPECT(test_string.ends_with("EF"sv));
     EXPECT(test_string.ends_with('F'));
     EXPECT(!test_string.ends_with('E'));
@@ -101,7 +101,7 @@ TEST_CASE(ends_with)
 
 TEST_CASE(copy_string)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     auto test_string_copy = test_string;
     EXPECT_EQ(test_string, test_string_copy);
     EXPECT_EQ(test_string.characters(), test_string_copy.characters());
@@ -109,7 +109,7 @@ TEST_CASE(copy_string)
 
 TEST_CASE(move_string)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     auto test_string_copy = test_string;
     auto test_string_move = move(test_string_copy);
     EXPECT_EQ(test_string, test_string_move);
@@ -118,25 +118,25 @@ TEST_CASE(move_string)
 
 TEST_CASE(repeated)
 {
-    EXPECT_EQ(DeprecatedString::repeated('x', 0), "");
-    EXPECT_EQ(DeprecatedString::repeated('x', 1), "x");
-    EXPECT_EQ(DeprecatedString::repeated('x', 2), "xx");
+    EXPECT_EQ(ByteString::repeated('x', 0), "");
+    EXPECT_EQ(ByteString::repeated('x', 1), "x");
+    EXPECT_EQ(ByteString::repeated('x', 2), "xx");
 }
 
 TEST_CASE(to_int)
 {
-    EXPECT_EQ(DeprecatedString("123").to_int().value(), 123);
-    EXPECT_EQ(DeprecatedString("-123").to_int().value(), -123);
+    EXPECT_EQ(ByteString("123").to_int().value(), 123);
+    EXPECT_EQ(ByteString("-123").to_int().value(), -123);
 }
 
 TEST_CASE(to_lowercase)
 {
-    EXPECT(DeprecatedString("ABC").to_lowercase() == "abc");
+    EXPECT(ByteString("ABC").to_lowercase() == "abc");
 }
 
 TEST_CASE(to_uppercase)
 {
-    EXPECT(DeprecatedString("AbC").to_uppercase() == "ABC");
+    EXPECT(ByteString("AbC").to_uppercase() == "ABC");
 }
 
 TEST_CASE(flystring)
@@ -148,12 +148,12 @@ TEST_CASE(flystring)
     }
 
     {
-        DeprecatedString a = "foo";
+        ByteString a = "foo";
         DeprecatedFlyString b = a;
         StringBuilder builder;
         builder.append('f');
         builder.append("oo"sv);
-        DeprecatedFlyString c = builder.to_deprecated_string();
+        DeprecatedFlyString c = builder.to_byte_string();
         EXPECT_EQ(a.impl(), b.impl());
         EXPECT_EQ(a.impl(), c.impl());
     }
@@ -161,7 +161,7 @@ TEST_CASE(flystring)
 
 TEST_CASE(replace)
 {
-    DeprecatedString test_string = "Well, hello Friends!";
+    ByteString test_string = "Well, hello Friends!";
 
     test_string = test_string.replace("Friends"sv, "Testers"sv, ReplaceMode::FirstOnly);
     EXPECT(test_string == "Well, hello Testers!");
@@ -172,7 +172,7 @@ TEST_CASE(replace)
     test_string = test_string.replace("!"sv, " :^)"sv, ReplaceMode::FirstOnly);
     EXPECT(test_string == "We're, he'reo Testers :^)");
 
-    test_string = DeprecatedString("111._.111._.111");
+    test_string = ByteString("111._.111._.111");
     test_string = test_string.replace("111"sv, "|||"sv, ReplaceMode::All);
     EXPECT(test_string == "|||._.|||._.|||");
 
@@ -182,7 +182,7 @@ TEST_CASE(replace)
 
 TEST_CASE(count)
 {
-    DeprecatedString test_string = "Well, hello Friends!";
+    ByteString test_string = "Well, hello Friends!";
     u32 count = test_string.count("Friends"sv);
     EXPECT(count == 1);
 
@@ -192,7 +192,7 @@ TEST_CASE(count)
     count = test_string.count("!"sv);
     EXPECT(count == 1);
 
-    test_string = DeprecatedString("111._.111._.111");
+    test_string = ByteString("111._.111._.111");
     count = test_string.count("111"sv);
     EXPECT(count == 3);
 
@@ -202,7 +202,7 @@ TEST_CASE(count)
 
 TEST_CASE(substring)
 {
-    DeprecatedString test = "abcdef";
+    ByteString test = "abcdef";
     EXPECT_EQ(test.substring(0, 6), test);
     EXPECT_EQ(test.substring(0, 3), "abc");
     EXPECT_EQ(test.substring(3, 3), "def");
@@ -212,7 +212,7 @@ TEST_CASE(substring)
 
 TEST_CASE(split)
 {
-    DeprecatedString test = "foo bar baz";
+    ByteString test = "foo bar baz";
     auto parts = test.split(' ');
     EXPECT_EQ(parts.size(), 3u);
     EXPECT_EQ(parts[0], "foo");
@@ -249,13 +249,13 @@ TEST_CASE(builder_zero_initial_capacity)
 {
     StringBuilder builder(0);
     builder.append(""sv);
-    auto built = builder.to_deprecated_string();
+    auto built = builder.to_byte_string();
     EXPECT_EQ(built.length(), 0u);
 }
 
 TEST_CASE(find)
 {
-    DeprecatedString a = "foobarbar";
+    ByteString a = "foobarbar";
     EXPECT_EQ(a.find("bar"sv), Optional<size_t> { 3 });
     EXPECT_EQ(a.find("baz"sv), Optional<size_t> {});
     EXPECT_EQ(a.find("bar"sv, 4), Optional<size_t> { 6 });
@@ -271,7 +271,7 @@ TEST_CASE(find)
 
 TEST_CASE(find_with_empty_needle)
 {
-    DeprecatedString string = "";
+    ByteString string = "";
     EXPECT_EQ(string.find(""sv), 0u);
     EXPECT_EQ(string.find_all(""sv), (Vector<size_t> { 0u }));
 
@@ -282,33 +282,33 @@ TEST_CASE(find_with_empty_needle)
 
 TEST_CASE(bijective_base)
 {
-    EXPECT_EQ(DeprecatedString::bijective_base_from(0), "A");
-    EXPECT_EQ(DeprecatedString::bijective_base_from(25), "Z");
-    EXPECT_EQ(DeprecatedString::bijective_base_from(26), "AA");
-    EXPECT_EQ(DeprecatedString::bijective_base_from(52), "BA");
-    EXPECT_EQ(DeprecatedString::bijective_base_from(701), "ZZ");
-    EXPECT_EQ(DeprecatedString::bijective_base_from(702), "AAA");
-    EXPECT_EQ(DeprecatedString::bijective_base_from(730), "ABC");
-    EXPECT_EQ(DeprecatedString::bijective_base_from(18277), "ZZZ");
+    EXPECT_EQ(ByteString::bijective_base_from(0), "A");
+    EXPECT_EQ(ByteString::bijective_base_from(25), "Z");
+    EXPECT_EQ(ByteString::bijective_base_from(26), "AA");
+    EXPECT_EQ(ByteString::bijective_base_from(52), "BA");
+    EXPECT_EQ(ByteString::bijective_base_from(701), "ZZ");
+    EXPECT_EQ(ByteString::bijective_base_from(702), "AAA");
+    EXPECT_EQ(ByteString::bijective_base_from(730), "ABC");
+    EXPECT_EQ(ByteString::bijective_base_from(18277), "ZZZ");
 }
 
 TEST_CASE(roman_numerals)
 {
-    auto zero = DeprecatedString::roman_number_from(0);
+    auto zero = ByteString::roman_number_from(0);
     EXPECT_EQ(zero, "");
 
-    auto one = DeprecatedString::roman_number_from(1);
+    auto one = ByteString::roman_number_from(1);
     EXPECT_EQ(one, "I");
 
-    auto nine = DeprecatedString::roman_number_from(9);
+    auto nine = ByteString::roman_number_from(9);
     EXPECT_EQ(nine, "IX");
 
-    auto fourty_eight = DeprecatedString::roman_number_from(48);
+    auto fourty_eight = ByteString::roman_number_from(48);
     EXPECT_EQ(fourty_eight, "XLVIII");
 
-    auto one_thousand_nine_hundred_ninety_eight = DeprecatedString::roman_number_from(1998);
+    auto one_thousand_nine_hundred_ninety_eight = ByteString::roman_number_from(1998);
     EXPECT_EQ(one_thousand_nine_hundred_ninety_eight, "MCMXCVIII");
 
-    auto four_thousand = DeprecatedString::roman_number_from(4000);
+    auto four_thousand = ByteString::roman_number_from(4000);
     EXPECT_EQ(four_thousand, "4000");
 }
diff --git a/Tests/AK/TestCircularDeque.cpp b/Tests/AK/TestCircularDeque.cpp
index 55da938080f..a843ca7d68e 100644
--- a/Tests/AK/TestCircularDeque.cpp
+++ b/Tests/AK/TestCircularDeque.cpp
@@ -6,8 +6,8 @@
 
 #include <LibTest/TestCase.h>
 
+#include <AK/ByteString.h>
 #include <AK/CircularDeque.h>
-#include <AK/DeprecatedString.h>
 #include <AK/StdLibExtras.h>
 
 TEST_CASE(enqueue_begin)
@@ -37,9 +37,9 @@ TEST_CASE(enqueue_begin)
 
 TEST_CASE(enqueue_begin_being_moved_from)
 {
-    CircularDeque<DeprecatedString, 2> strings;
+    CircularDeque<ByteString, 2> strings;
 
-    DeprecatedString str { "test" };
+    ByteString str { "test" };
     strings.enqueue_begin(move(str));
     EXPECT(str.is_empty());
 }
diff --git a/Tests/AK/TestCircularQueue.cpp b/Tests/AK/TestCircularQueue.cpp
index 337164725d0..e3ae81b4bd1 100644
--- a/Tests/AK/TestCircularQueue.cpp
+++ b/Tests/AK/TestCircularQueue.cpp
@@ -6,8 +6,8 @@
 
 #include <LibTest/TestCase.h>
 
+#include <AK/ByteString.h>
 #include <AK/CircularQueue.h>
-#include <AK/DeprecatedString.h>
 
 TEST_CASE(basic)
 {
@@ -28,7 +28,7 @@ TEST_CASE(basic)
 
 TEST_CASE(complex_type)
 {
-    CircularQueue<DeprecatedString, 2> strings;
+    CircularQueue<ByteString, 2> strings;
 
     strings.enqueue("ABC");
     strings.enqueue("DEF");
@@ -44,7 +44,7 @@ TEST_CASE(complex_type)
 
 TEST_CASE(complex_type_clear)
 {
-    CircularQueue<DeprecatedString, 5> strings;
+    CircularQueue<ByteString, 5> strings;
     strings.enqueue("xxx");
     strings.enqueue("xxx");
     strings.enqueue("xxx");
diff --git a/Tests/AK/TestDisjointChunks.cpp b/Tests/AK/TestDisjointChunks.cpp
index 15fd5319b3d..cc24d6d045a 100644
--- a/Tests/AK/TestDisjointChunks.cpp
+++ b/Tests/AK/TestDisjointChunks.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/DisjointChunks.h>
 #include <AK/FixedArray.h>
 #include <AK/Vector.h>
diff --git a/Tests/AK/TestFixedPoint.cpp b/Tests/AK/TestFixedPoint.cpp
index a59c118225b..15683e8ba77 100644
--- a/Tests/AK/TestFixedPoint.cpp
+++ b/Tests/AK/TestFixedPoint.cpp
@@ -168,134 +168,134 @@ TEST_CASE(cast)
 
 TEST_CASE(formatter)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(123.456)), "123.455993"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(-123.456)), "-123.455993"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<4>(123.456)), "123.4375"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<4>(-123.456)), "-123.4375"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16> {}), "0"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(0.1)), "0.100006"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(0.02)), "0.020004"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(0.003)), "0.003005"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(0.0004)), "0.000396"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(0.0000000005)), "0"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(-0.1)), "-0.100006"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(-0.02)), "-0.020004"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", FixedPoint<16>(-0.0000000005)), "0"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(123.456)), "123.455993"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(-123.456)), "-123.455993"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<4>(123.456)), "123.4375"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<4>(-123.456)), "-123.4375"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16> {}), "0"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(0.1)), "0.100006"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(0.02)), "0.020004"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(0.003)), "0.003005"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(0.0004)), "0.000396"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(0.0000000005)), "0"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(-0.1)), "-0.100006"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(-0.02)), "-0.020004"sv);
+    EXPECT_EQ(ByteString::formatted("{}", FixedPoint<16>(-0.0000000005)), "0"sv);
 
-    EXPECT_EQ(DeprecatedString::formatted("{}", Type(-1)), "-1"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", Type(-2)), "-2"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{}", Type(-3)), "-3"sv);
+    EXPECT_EQ(ByteString::formatted("{}", Type(-1)), "-1"sv);
+    EXPECT_EQ(ByteString::formatted("{}", Type(-2)), "-2"sv);
+    EXPECT_EQ(ByteString::formatted("{}", Type(-3)), "-3"sv);
 
     // exact representation
-    EXPECT_EQ(DeprecatedString::formatted("{:.30}", FixedPoint<16>(123.456)), "123.45599365234375"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30}", FixedPoint<16>(-0.1)), "-0.100006103515625"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30}", FixedPoint<16>(-0.02)), "-0.0200042724609375"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30}", FixedPoint<16>(123.456)), "123.45599365234375"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30}", FixedPoint<16>(-0.1)), "-0.100006103515625"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30}", FixedPoint<16>(-0.02)), "-0.0200042724609375"sv);
 
     // maximum fraction per precision; 1 - 2^-precision
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<7, u64>::create_raw((1ull << 7) - 1)), "0.99218750000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<8, u64>::create_raw((1ull << 8) - 1)), "0.99609375000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<9, u64>::create_raw((1ull << 9) - 1)), "0.99804687500000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<10, u64>::create_raw((1ull << 10) - 1)), "0.99902343750000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<11, u64>::create_raw((1ull << 11) - 1)), "0.99951171875000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<12, u64>::create_raw((1ull << 12) - 1)), "0.99975585937500000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<13, u64>::create_raw((1ull << 13) - 1)), "0.99987792968750000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<14, u64>::create_raw((1ull << 14) - 1)), "0.99993896484375000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<15, u64>::create_raw((1ull << 15) - 1)), "0.99996948242187500000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<16, u64>::create_raw((1ull << 16) - 1)), "0.99998474121093750000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<17, u64>::create_raw((1ull << 17) - 1)), "0.99999237060546875000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<18, u64>::create_raw((1ull << 18) - 1)), "0.99999618530273437500"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.20}", AK::FixedPoint<19, u64>::create_raw((1ull << 19) - 1)), "0.99999809265136718750"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<7, u64>::create_raw((1ull << 7) - 1)), "0.99218750000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<8, u64>::create_raw((1ull << 8) - 1)), "0.99609375000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<9, u64>::create_raw((1ull << 9) - 1)), "0.99804687500000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<10, u64>::create_raw((1ull << 10) - 1)), "0.99902343750000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<11, u64>::create_raw((1ull << 11) - 1)), "0.99951171875000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<12, u64>::create_raw((1ull << 12) - 1)), "0.99975585937500000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<13, u64>::create_raw((1ull << 13) - 1)), "0.99987792968750000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<14, u64>::create_raw((1ull << 14) - 1)), "0.99993896484375000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<15, u64>::create_raw((1ull << 15) - 1)), "0.99996948242187500000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<16, u64>::create_raw((1ull << 16) - 1)), "0.99998474121093750000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<17, u64>::create_raw((1ull << 17) - 1)), "0.99999237060546875000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<18, u64>::create_raw((1ull << 18) - 1)), "0.99999618530273437500"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.20}", AK::FixedPoint<19, u64>::create_raw((1ull << 19) - 1)), "0.99999809265136718750"sv);
     // maximum factor and precision >= 20 bits/digits will overflow u64: (5^20)*(2^20 - 1) > 2^64
-    // EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<20, u64>::create_raw((1ull << 20) - 1)), "0.99999904632568359375"sv);
+    // EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<20, u64>::create_raw((1ull << 20) - 1)), "0.99999904632568359375"sv);
 
     // minimum fraction per precision; 2^-precision
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<7, u64>::create_raw(1)), "0.007812500000000000000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<8, u64>::create_raw(1)), "0.003906250000000000000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<9, u64>::create_raw(1)), "0.001953125000000000000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<10, u64>::create_raw(1)), "0.000976562500000000000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<11, u64>::create_raw(1)), "0.000488281250000000000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<12, u64>::create_raw(1)), "0.000244140625000000000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<13, u64>::create_raw(1)), "0.000122070312500000000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<14, u64>::create_raw(1)), "0.000061035156250000000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<15, u64>::create_raw(1)), "0.000030517578125000000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<16, u64>::create_raw(1)), "0.000015258789062500000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<17, u64>::create_raw(1)), "0.000007629394531250000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<18, u64>::create_raw(1)), "0.000003814697265625000000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<19, u64>::create_raw(1)), "0.000001907348632812500000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<20, u64>::create_raw(1)), "0.000000953674316406250000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<21, u64>::create_raw(1)), "0.000000476837158203125000000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<22, u64>::create_raw(1)), "0.000000238418579101562500000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<23, u64>::create_raw(1)), "0.000000119209289550781250000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<24, u64>::create_raw(1)), "0.000000059604644775390625000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<25, u64>::create_raw(1)), "0.000000029802322387695312500000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<26, u64>::create_raw(1)), "0.000000014901161193847656250000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<27, u64>::create_raw(1)), "0.000000007450580596923828125000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<7, u64>::create_raw(1)), "0.007812500000000000000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<8, u64>::create_raw(1)), "0.003906250000000000000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<9, u64>::create_raw(1)), "0.001953125000000000000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<10, u64>::create_raw(1)), "0.000976562500000000000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<11, u64>::create_raw(1)), "0.000488281250000000000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<12, u64>::create_raw(1)), "0.000244140625000000000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<13, u64>::create_raw(1)), "0.000122070312500000000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<14, u64>::create_raw(1)), "0.000061035156250000000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<15, u64>::create_raw(1)), "0.000030517578125000000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<16, u64>::create_raw(1)), "0.000015258789062500000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<17, u64>::create_raw(1)), "0.000007629394531250000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<18, u64>::create_raw(1)), "0.000003814697265625000000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<19, u64>::create_raw(1)), "0.000001907348632812500000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<20, u64>::create_raw(1)), "0.000000953674316406250000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<21, u64>::create_raw(1)), "0.000000476837158203125000000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<22, u64>::create_raw(1)), "0.000000238418579101562500000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<23, u64>::create_raw(1)), "0.000000119209289550781250000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<24, u64>::create_raw(1)), "0.000000059604644775390625000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<25, u64>::create_raw(1)), "0.000000029802322387695312500000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<26, u64>::create_raw(1)), "0.000000014901161193847656250000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<27, u64>::create_raw(1)), "0.000000007450580596923828125000"sv);
     // minimum factor and precision >= 28 bits/digits will overflow u64: (5^28)*(1) > 2^64
-    // EXPECT_EQ(DeprecatedString::formatted("{:0.30}", AK::FixedPoint<28, u64>::create_raw(1)), "0.000000003725290298461914062500"sv);
+    // EXPECT_EQ(ByteString::formatted("{:0.30}", AK::FixedPoint<28, u64>::create_raw(1)), "0.000000003725290298461914062500"sv);
 
-    EXPECT_EQ(DeprecatedString::formatted("{:a}", FixedPoint<16>(42.42)), "2a.6b85"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:o}", FixedPoint<16>(42.42)), "52.327024"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:b}", FixedPoint<16>(42.42)), "101010.01101"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.10a}", FixedPoint<16>(69.69)), "45.b0a4000000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.10o}", FixedPoint<16>(69.69)), "105.5412200000"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:0.10b}", FixedPoint<16>(69.69)), "1000101.1011000010"sv);
+    EXPECT_EQ(ByteString::formatted("{:a}", FixedPoint<16>(42.42)), "2a.6b85"sv);
+    EXPECT_EQ(ByteString::formatted("{:o}", FixedPoint<16>(42.42)), "52.327024"sv);
+    EXPECT_EQ(ByteString::formatted("{:b}", FixedPoint<16>(42.42)), "101010.01101"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.10a}", FixedPoint<16>(69.69)), "45.b0a4000000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.10o}", FixedPoint<16>(69.69)), "105.5412200000"sv);
+    EXPECT_EQ(ByteString::formatted("{:0.10b}", FixedPoint<16>(69.69)), "1000101.1011000010"sv);
 
-    EXPECT_EQ(DeprecatedString::formatted("{:.30o}", AK::FixedPoint<13, u64>::create_raw(1)), "0.00004"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30b}", AK::FixedPoint<13, u64>::create_raw(1)), "0.0000000000001"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30o}", AK::FixedPoint<21, u64>::create_raw(0211234567)), "21.1234567"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30b}", AK::FixedPoint<13, u64>::create_raw(0b110011011010110)), "11.001101101011"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30o}", AK::FixedPoint<11, u64>::create_raw((1ull << 11) - 1)), "0.7776"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30b}", AK::FixedPoint<11, u64>::create_raw((1ull << 11) - 1)), "0.11111111111"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30o}", AK::FixedPoint<13, u64>::create_raw(1)), "0.00004"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30b}", AK::FixedPoint<13, u64>::create_raw(1)), "0.0000000000001"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30o}", AK::FixedPoint<21, u64>::create_raw(0211234567)), "21.1234567"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30b}", AK::FixedPoint<13, u64>::create_raw(0b110011011010110)), "11.001101101011"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30o}", AK::FixedPoint<11, u64>::create_raw((1ull << 11) - 1)), "0.7776"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30b}", AK::FixedPoint<11, u64>::create_raw((1ull << 11) - 1)), "0.11111111111"sv);
 
     // maximum fraction per precision rendered in hexadecimal; 1 - 2^-precision; no overflow
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<7, u64>::create_raw((1ull << 7) - 1)), "0.fe"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<8, u64>::create_raw((1ull << 8) - 1)), "0.ff"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<9, u64>::create_raw((1ull << 9) - 1)), "0.ff8"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<10, u64>::create_raw((1ull << 10) - 1)), "0.ffc"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<11, u64>::create_raw((1ull << 11) - 1)), "0.ffe"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<12, u64>::create_raw((1ull << 12) - 1)), "0.fff"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<13, u64>::create_raw((1ull << 13) - 1)), "0.fff8"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<14, u64>::create_raw((1ull << 14) - 1)), "0.fffc"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<15, u64>::create_raw((1ull << 15) - 1)), "0.fffe"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<16, u64>::create_raw((1ull << 16) - 1)), "0.ffff"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<17, u64>::create_raw((1ull << 17) - 1)), "0.ffff8"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<18, u64>::create_raw((1ull << 18) - 1)), "0.ffffc"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<19, u64>::create_raw((1ull << 19) - 1)), "0.ffffe"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<20, u64>::create_raw((1ull << 20) - 1)), "0.fffff"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<21, u64>::create_raw((1ull << 21) - 1)), "0.fffff8"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<7, u64>::create_raw((1ull << 7) - 1)), "0.fe"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<8, u64>::create_raw((1ull << 8) - 1)), "0.ff"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<9, u64>::create_raw((1ull << 9) - 1)), "0.ff8"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<10, u64>::create_raw((1ull << 10) - 1)), "0.ffc"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<11, u64>::create_raw((1ull << 11) - 1)), "0.ffe"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<12, u64>::create_raw((1ull << 12) - 1)), "0.fff"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<13, u64>::create_raw((1ull << 13) - 1)), "0.fff8"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<14, u64>::create_raw((1ull << 14) - 1)), "0.fffc"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<15, u64>::create_raw((1ull << 15) - 1)), "0.fffe"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<16, u64>::create_raw((1ull << 16) - 1)), "0.ffff"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<17, u64>::create_raw((1ull << 17) - 1)), "0.ffff8"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<18, u64>::create_raw((1ull << 18) - 1)), "0.ffffc"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<19, u64>::create_raw((1ull << 19) - 1)), "0.ffffe"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<20, u64>::create_raw((1ull << 20) - 1)), "0.fffff"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<21, u64>::create_raw((1ull << 21) - 1)), "0.fffff8"sv);
     // ...skip some precisions
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<56, u64>::create_raw((1ull << 56) - 1)), "0.ffffffffffffff"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<57, u64>::create_raw((1ull << 57) - 1)), "0.ffffffffffffff8"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<58, u64>::create_raw((1ull << 58) - 1)), "0.ffffffffffffffc"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<59, u64>::create_raw((1ull << 59) - 1)), "0.ffffffffffffffe"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<60, u64>::create_raw((1ull << 60) - 1)), "0.fffffffffffffff"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<61, u64>::create_raw((1ull << 61) - 1)), "0.fffffffffffffff8"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<62, u64>::create_raw((1ull << 62) - 1)), "0.fffffffffffffffc"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<63, u64>::create_raw((1ull << 63) - 1)), "0.fffffffffffffffe"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<56, u64>::create_raw((1ull << 56) - 1)), "0.ffffffffffffff"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<57, u64>::create_raw((1ull << 57) - 1)), "0.ffffffffffffff8"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<58, u64>::create_raw((1ull << 58) - 1)), "0.ffffffffffffffc"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<59, u64>::create_raw((1ull << 59) - 1)), "0.ffffffffffffffe"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<60, u64>::create_raw((1ull << 60) - 1)), "0.fffffffffffffff"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<61, u64>::create_raw((1ull << 61) - 1)), "0.fffffffffffffff8"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<62, u64>::create_raw((1ull << 62) - 1)), "0.fffffffffffffffc"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<63, u64>::create_raw((1ull << 63) - 1)), "0.fffffffffffffffe"sv);
 
     // minimum fraction per precision rendered in hexadecimal; 2^-precision; no overflow
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<7, u64>::create_raw(1)), "0.02"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<8, u64>::create_raw(1)), "0.01"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<9, u64>::create_raw(1)), "0.008"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<10, u64>::create_raw(1)), "0.004"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<11, u64>::create_raw(1)), "0.002"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<12, u64>::create_raw(1)), "0.001"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<13, u64>::create_raw(1)), "0.0008"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<14, u64>::create_raw(1)), "0.0004"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<15, u64>::create_raw(1)), "0.0002"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<16, u64>::create_raw(1)), "0.0001"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<17, u64>::create_raw(1)), "0.00008"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<18, u64>::create_raw(1)), "0.00004"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<19, u64>::create_raw(1)), "0.00002"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<20, u64>::create_raw(1)), "0.00001"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<21, u64>::create_raw(1)), "0.000008"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<7, u64>::create_raw(1)), "0.02"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<8, u64>::create_raw(1)), "0.01"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<9, u64>::create_raw(1)), "0.008"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<10, u64>::create_raw(1)), "0.004"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<11, u64>::create_raw(1)), "0.002"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<12, u64>::create_raw(1)), "0.001"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<13, u64>::create_raw(1)), "0.0008"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<14, u64>::create_raw(1)), "0.0004"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<15, u64>::create_raw(1)), "0.0002"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<16, u64>::create_raw(1)), "0.0001"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<17, u64>::create_raw(1)), "0.00008"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<18, u64>::create_raw(1)), "0.00004"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<19, u64>::create_raw(1)), "0.00002"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<20, u64>::create_raw(1)), "0.00001"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<21, u64>::create_raw(1)), "0.000008"sv);
     // ..skip some precisions
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<56, u64>::create_raw(1)), "0.00000000000001"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<57, u64>::create_raw(1)), "0.000000000000008"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<58, u64>::create_raw(1)), "0.000000000000004"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<59, u64>::create_raw(1)), "0.000000000000002"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<60, u64>::create_raw(1)), "0.000000000000001"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<61, u64>::create_raw(1)), "0.0000000000000008"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<62, u64>::create_raw(1)), "0.0000000000000004"sv);
-    EXPECT_EQ(DeprecatedString::formatted("{:.30a}", AK::FixedPoint<63, u64>::create_raw(1)), "0.0000000000000002"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<56, u64>::create_raw(1)), "0.00000000000001"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<57, u64>::create_raw(1)), "0.000000000000008"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<58, u64>::create_raw(1)), "0.000000000000004"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<59, u64>::create_raw(1)), "0.000000000000002"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<60, u64>::create_raw(1)), "0.000000000000001"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<61, u64>::create_raw(1)), "0.0000000000000008"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<62, u64>::create_raw(1)), "0.0000000000000004"sv);
+    EXPECT_EQ(ByteString::formatted("{:.30a}", AK::FixedPoint<63, u64>::create_raw(1)), "0.0000000000000002"sv);
 }
diff --git a/Tests/AK/TestFormat.cpp b/Tests/AK/TestFormat.cpp
index 32fae024a46..69b96d1ec77 100644
--- a/Tests/AK/TestFormat.cpp
+++ b/Tests/AK/TestFormat.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <AK/Vector.h>
 #include <math.h>
@@ -20,55 +20,55 @@ TEST_CASE(is_integral_works_properly)
 
 TEST_CASE(format_string_literals)
 {
-    EXPECT_EQ(DeprecatedString::formatted("prefix-{}-suffix", "abc"), "prefix-abc-suffix");
-    EXPECT_EQ(DeprecatedString::formatted("{}{}{}", "a", "b", "c"), "abc");
+    EXPECT_EQ(ByteString::formatted("prefix-{}-suffix", "abc"), "prefix-abc-suffix");
+    EXPECT_EQ(ByteString::formatted("{}{}{}", "a", "b", "c"), "abc");
 }
 
 TEST_CASE(format_integers)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{}", 42u), "42");
-    EXPECT_EQ(DeprecatedString::formatted("{:4}", 42u), "  42");
-    EXPECT_EQ(DeprecatedString::formatted("{:08}", 42u), "00000042");
-    EXPECT_EQ(DeprecatedString::formatted("{:7}", -17), "    -17");
-    EXPECT_EQ(DeprecatedString::formatted("{}", -17), "-17");
-    EXPECT_EQ(DeprecatedString::formatted("{:04}", 13), "0013");
-    EXPECT_EQ(DeprecatedString::formatted("{:08x}", 4096), "00001000");
-    EXPECT_EQ(DeprecatedString::formatted("{:x}", 0x1111222233334444ull), "1111222233334444");
-    EXPECT_EQ(DeprecatedString::formatted("{:4}", 12345678), "12345678");
-    EXPECT_EQ(DeprecatedString::formatted("{}", AK::NumericLimits<i64>::min()), "-9223372036854775808");
-    EXPECT_EQ(DeprecatedString::formatted("{:x}", AK::NumericLimits<i64>::min()), "-8000000000000000");
-    EXPECT_EQ(DeprecatedString::formatted("{:'}", 0), "0");
-    EXPECT_EQ(DeprecatedString::formatted("{:'}", 4096), "4,096");
-    EXPECT_EQ(DeprecatedString::formatted("{:'}", 16777216), "16,777,216");
-    EXPECT_EQ(DeprecatedString::formatted("{:'}", AK::NumericLimits<u64>::max()), "18,446,744,073,709,551,615");
-    EXPECT_EQ(DeprecatedString::formatted("{:'}", AK::NumericLimits<u64>::max()), "18,446,744,073,709,551,615");
-    EXPECT_EQ(DeprecatedString::formatted("{:'}", AK::NumericLimits<i64>::min() + 1), "-9,223,372,036,854,775,807");
-    EXPECT_EQ(DeprecatedString::formatted("{:'x}", 0), "0");
-    EXPECT_EQ(DeprecatedString::formatted("{:'x}", 16777216), "1,000,000");
-    EXPECT_EQ(DeprecatedString::formatted("{:'x}", AK::NumericLimits<u64>::max()), "f,fff,fff,fff,fff,fff");
-    EXPECT_EQ(DeprecatedString::formatted("{:'x}", AK::NumericLimits<i64>::min() + 1), "-7,fff,fff,fff,fff,fff");
-    EXPECT_EQ(DeprecatedString::formatted("{:'b}", AK::NumericLimits<u64>::max()), "1,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111");
+    EXPECT_EQ(ByteString::formatted("{}", 42u), "42");
+    EXPECT_EQ(ByteString::formatted("{:4}", 42u), "  42");
+    EXPECT_EQ(ByteString::formatted("{:08}", 42u), "00000042");
+    EXPECT_EQ(ByteString::formatted("{:7}", -17), "    -17");
+    EXPECT_EQ(ByteString::formatted("{}", -17), "-17");
+    EXPECT_EQ(ByteString::formatted("{:04}", 13), "0013");
+    EXPECT_EQ(ByteString::formatted("{:08x}", 4096), "00001000");
+    EXPECT_EQ(ByteString::formatted("{:x}", 0x1111222233334444ull), "1111222233334444");
+    EXPECT_EQ(ByteString::formatted("{:4}", 12345678), "12345678");
+    EXPECT_EQ(ByteString::formatted("{}", AK::NumericLimits<i64>::min()), "-9223372036854775808");
+    EXPECT_EQ(ByteString::formatted("{:x}", AK::NumericLimits<i64>::min()), "-8000000000000000");
+    EXPECT_EQ(ByteString::formatted("{:'}", 0), "0");
+    EXPECT_EQ(ByteString::formatted("{:'}", 4096), "4,096");
+    EXPECT_EQ(ByteString::formatted("{:'}", 16777216), "16,777,216");
+    EXPECT_EQ(ByteString::formatted("{:'}", AK::NumericLimits<u64>::max()), "18,446,744,073,709,551,615");
+    EXPECT_EQ(ByteString::formatted("{:'}", AK::NumericLimits<u64>::max()), "18,446,744,073,709,551,615");
+    EXPECT_EQ(ByteString::formatted("{:'}", AK::NumericLimits<i64>::min() + 1), "-9,223,372,036,854,775,807");
+    EXPECT_EQ(ByteString::formatted("{:'x}", 0), "0");
+    EXPECT_EQ(ByteString::formatted("{:'x}", 16777216), "1,000,000");
+    EXPECT_EQ(ByteString::formatted("{:'x}", AK::NumericLimits<u64>::max()), "f,fff,fff,fff,fff,fff");
+    EXPECT_EQ(ByteString::formatted("{:'x}", AK::NumericLimits<i64>::min() + 1), "-7,fff,fff,fff,fff,fff");
+    EXPECT_EQ(ByteString::formatted("{:'b}", AK::NumericLimits<u64>::max()), "1,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111,111");
 }
 
 TEST_CASE(reorder_format_arguments)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{1}{0}", "a", "b"), "ba");
-    EXPECT_EQ(DeprecatedString::formatted("{0}{1}", "a", "b"), "ab");
+    EXPECT_EQ(ByteString::formatted("{1}{0}", "a", "b"), "ba");
+    EXPECT_EQ(ByteString::formatted("{0}{1}", "a", "b"), "ab");
     // Compiletime check bypass: ignoring a passed argument.
-    EXPECT_EQ(DeprecatedString::formatted("{0}{0}{0}"sv, "a", "b"), "aaa");
+    EXPECT_EQ(ByteString::formatted("{0}{0}{0}"sv, "a", "b"), "aaa");
     // Compiletime check bypass: ignoring a passed argument.
-    EXPECT_EQ(DeprecatedString::formatted("{1}{}{0}"sv, "a", "b", "c"), "baa");
+    EXPECT_EQ(ByteString::formatted("{1}{}{0}"sv, "a", "b", "c"), "baa");
 }
 
 TEST_CASE(escape_braces)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{{{}", "foo"), "{foo");
-    EXPECT_EQ(DeprecatedString::formatted("{}}}", "bar"), "bar}");
+    EXPECT_EQ(ByteString::formatted("{{{}", "foo"), "{foo");
+    EXPECT_EQ(ByteString::formatted("{}}}", "bar"), "bar}");
 }
 
 TEST_CASE(everything)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{{{:04}/{}/{0:8}/{1}", 42u, "foo"), "{0042/foo/      42/foo");
+    EXPECT_EQ(ByteString::formatted("{{{:04}/{}/{0:8}/{1}", 42u, "foo"), "{0042/foo/      42/foo");
 }
 
 TEST_CASE(string_builder)
@@ -77,92 +77,92 @@ TEST_CASE(string_builder)
     builder.appendff(" {}  ", 42);
     builder.appendff("{1}{0} ", 1, 2);
 
-    EXPECT_EQ(builder.to_deprecated_string(), " 42  21 ");
+    EXPECT_EQ(builder.to_byte_string(), " 42  21 ");
 }
 
 TEST_CASE(format_without_arguments)
 {
-    EXPECT_EQ(DeprecatedString::formatted("foo"), "foo");
+    EXPECT_EQ(ByteString::formatted("foo"), "foo");
 }
 
 TEST_CASE(format_upper_case_integer)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:4X}", 0xff), "  FF");
-    EXPECT_EQ(DeprecatedString::formatted("{:#4X}", 0xff), "0XFF");
+    EXPECT_EQ(ByteString::formatted("{:4X}", 0xff), "  FF");
+    EXPECT_EQ(ByteString::formatted("{:#4X}", 0xff), "0XFF");
 
-    EXPECT_EQ(DeprecatedString::formatted("{:b}", 0xff), "11111111");
-    EXPECT_EQ(DeprecatedString::formatted("{:B}", 0xff), "11111111");
-    EXPECT_EQ(DeprecatedString::formatted("{:#b}", 0xff), "0b11111111");
+    EXPECT_EQ(ByteString::formatted("{:b}", 0xff), "11111111");
+    EXPECT_EQ(ByteString::formatted("{:B}", 0xff), "11111111");
+    EXPECT_EQ(ByteString::formatted("{:#b}", 0xff), "0b11111111");
 }
 
 TEST_CASE(format_aligned)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:*<8}", 13), "13******");
-    EXPECT_EQ(DeprecatedString::formatted("{:*^8}", 13), "***13***");
-    EXPECT_EQ(DeprecatedString::formatted("{:*>8}", 13), "******13");
-    EXPECT_EQ(DeprecatedString::formatted("{:*>+8}", 13), "*****+13");
-    EXPECT_EQ(DeprecatedString::formatted("{:*^ 8}", 13), "** 13***");
+    EXPECT_EQ(ByteString::formatted("{:*<8}", 13), "13******");
+    EXPECT_EQ(ByteString::formatted("{:*^8}", 13), "***13***");
+    EXPECT_EQ(ByteString::formatted("{:*>8}", 13), "******13");
+    EXPECT_EQ(ByteString::formatted("{:*>+8}", 13), "*****+13");
+    EXPECT_EQ(ByteString::formatted("{:*^ 8}", 13), "** 13***");
 }
 
 TEST_CASE(format_octal)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:o}", 0744), "744");
-    EXPECT_EQ(DeprecatedString::formatted("{:#o}", 0744), "0744");
-    EXPECT_EQ(DeprecatedString::formatted("{:'o}", 054321), "54,321");
-    EXPECT_EQ(DeprecatedString::formatted("{:'o}", 0567012340), "567,012,340");
+    EXPECT_EQ(ByteString::formatted("{:o}", 0744), "744");
+    EXPECT_EQ(ByteString::formatted("{:#o}", 0744), "0744");
+    EXPECT_EQ(ByteString::formatted("{:'o}", 054321), "54,321");
+    EXPECT_EQ(ByteString::formatted("{:'o}", 0567012340), "567,012,340");
 }
 
 TEST_CASE(zero_pad)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{: <010}", 42), "42        ");
-    EXPECT_EQ(DeprecatedString::formatted("{:010}", 42), "0000000042");
-    EXPECT_EQ(DeprecatedString::formatted("{:/^010}", 42), "////42////");
-    EXPECT_EQ(DeprecatedString::formatted("{:04x}", -32), "-0020");
-    EXPECT_EQ(DeprecatedString::formatted("{:#06x}", -64), "-0x000040");
+    EXPECT_EQ(ByteString::formatted("{: <010}", 42), "42        ");
+    EXPECT_EQ(ByteString::formatted("{:010}", 42), "0000000042");
+    EXPECT_EQ(ByteString::formatted("{:/^010}", 42), "////42////");
+    EXPECT_EQ(ByteString::formatted("{:04x}", -32), "-0020");
+    EXPECT_EQ(ByteString::formatted("{:#06x}", -64), "-0x000040");
 }
 
 TEST_CASE(replacement_field)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:*>{1}}", 13, static_cast<size_t>(10)), "********13");
-    EXPECT_EQ(DeprecatedString::formatted("{:*<{1}}", 7, 4), "7***");
+    EXPECT_EQ(ByteString::formatted("{:*>{1}}", 13, static_cast<size_t>(10)), "********13");
+    EXPECT_EQ(ByteString::formatted("{:*<{1}}", 7, 4), "7***");
     // Compiletime check bypass: intentionally ignoring extra arguments
-    EXPECT_EQ(DeprecatedString::formatted("{:{2}}"sv, -5, 8, 16), "              -5");
-    EXPECT_EQ(DeprecatedString::formatted("{{{:*^{1}}}}", 1, 3), "{*1*}");
-    EXPECT_EQ(DeprecatedString::formatted("{:0{}}", 1, 3), "001");
+    EXPECT_EQ(ByteString::formatted("{:{2}}"sv, -5, 8, 16), "              -5");
+    EXPECT_EQ(ByteString::formatted("{{{:*^{1}}}}", 1, 3), "{*1*}");
+    EXPECT_EQ(ByteString::formatted("{:0{}}", 1, 3), "001");
 }
 
 TEST_CASE(replacement_field_regression)
 {
     // FIXME: Compiletime check bypass: cannot parse '}}' correctly.
-    EXPECT_EQ(DeprecatedString::formatted("{:{}}"sv, "", static_cast<unsigned long>(6)), "      ");
+    EXPECT_EQ(ByteString::formatted("{:{}}"sv, "", static_cast<unsigned long>(6)), "      ");
 }
 
 TEST_CASE(complex_string_specifiers)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:.8}", "123456789"), "12345678");
-    EXPECT_EQ(DeprecatedString::formatted("{:9}", "abcd"), "abcd     ");
-    EXPECT_EQ(DeprecatedString::formatted("{:>9}", "abcd"), "     abcd");
-    EXPECT_EQ(DeprecatedString::formatted("{:^9}", "abcd"), "  abcd   ");
-    EXPECT_EQ(DeprecatedString::formatted("{:4.6}", "a"), "a   ");
-    EXPECT_EQ(DeprecatedString::formatted("{:4.6}", "abcdef"), "abcdef");
-    EXPECT_EQ(DeprecatedString::formatted("{:4.6}", "abcdefghi"), "abcdef");
+    EXPECT_EQ(ByteString::formatted("{:.8}", "123456789"), "12345678");
+    EXPECT_EQ(ByteString::formatted("{:9}", "abcd"), "abcd     ");
+    EXPECT_EQ(ByteString::formatted("{:>9}", "abcd"), "     abcd");
+    EXPECT_EQ(ByteString::formatted("{:^9}", "abcd"), "  abcd   ");
+    EXPECT_EQ(ByteString::formatted("{:4.6}", "a"), "a   ");
+    EXPECT_EQ(ByteString::formatted("{:4.6}", "abcdef"), "abcdef");
+    EXPECT_EQ(ByteString::formatted("{:4.6}", "abcdefghi"), "abcdef");
 }
 
 TEST_CASE(cast_integer_to_character)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:c}", static_cast<int>('a')), "a");
-    EXPECT_EQ(DeprecatedString::formatted("{:c}", static_cast<unsigned int>('f')), "f");
+    EXPECT_EQ(ByteString::formatted("{:c}", static_cast<int>('a')), "a");
+    EXPECT_EQ(ByteString::formatted("{:c}", static_cast<unsigned int>('f')), "f");
 }
 
 TEST_CASE(boolean_values)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{}", true), "true");
-    EXPECT_EQ(DeprecatedString::formatted("{}", false), "false");
-    EXPECT_EQ(DeprecatedString::formatted("{:6}", true), "true  ");
-    EXPECT_EQ(DeprecatedString::formatted("{:>4}", false), "false");
-    EXPECT_EQ(DeprecatedString::formatted("{:d}", false), "0");
-    EXPECT_EQ(DeprecatedString::formatted("{:d}", true), "1");
-    EXPECT_EQ(DeprecatedString::formatted("{:#08x}", true), "0x00000001");
+    EXPECT_EQ(ByteString::formatted("{}", true), "true");
+    EXPECT_EQ(ByteString::formatted("{}", false), "false");
+    EXPECT_EQ(ByteString::formatted("{:6}", true), "true  ");
+    EXPECT_EQ(ByteString::formatted("{:>4}", false), "false");
+    EXPECT_EQ(ByteString::formatted("{:d}", false), "0");
+    EXPECT_EQ(ByteString::formatted("{:d}", true), "1");
+    EXPECT_EQ(ByteString::formatted("{:#08x}", true), "0x00000001");
 }
 
 TEST_CASE(pointers)
@@ -170,13 +170,13 @@ TEST_CASE(pointers)
     void* ptr = reinterpret_cast<void*>(0x4000);
 
     if (sizeof(void*) == 4) {
-        EXPECT_EQ(DeprecatedString::formatted("{:p}", 32), "0x00000020");
-        EXPECT_EQ(DeprecatedString::formatted("{:p}", ptr), "0x00004000");
-        EXPECT_EQ(DeprecatedString::formatted("{}", ptr), "0x00004000");
+        EXPECT_EQ(ByteString::formatted("{:p}", 32), "0x00000020");
+        EXPECT_EQ(ByteString::formatted("{:p}", ptr), "0x00004000");
+        EXPECT_EQ(ByteString::formatted("{}", ptr), "0x00004000");
     } else if (sizeof(void*) == 8) {
-        EXPECT_EQ(DeprecatedString::formatted("{:p}", 32), "0x0000000000000020");
-        EXPECT_EQ(DeprecatedString::formatted("{:p}", ptr), "0x0000000000004000");
-        EXPECT_EQ(DeprecatedString::formatted("{}", ptr), "0x0000000000004000");
+        EXPECT_EQ(ByteString::formatted("{:p}", 32), "0x0000000000000020");
+        EXPECT_EQ(ByteString::formatted("{:p}", ptr), "0x0000000000004000");
+        EXPECT_EQ(ByteString::formatted("{}", ptr), "0x0000000000004000");
     } else {
         VERIFY_NOT_REACHED();
     }
@@ -188,12 +188,12 @@ TEST_CASE(pointers)
 // This is a bit scary, thus this test. At least this test should fail in this case.
 TEST_CASE(ensure_that_format_works)
 {
-    if (DeprecatedString::formatted("FAIL") != "FAIL") {
+    if (ByteString::formatted("FAIL") != "FAIL") {
         fprintf(stderr, "FAIL\n");
         exit(1);
     }
 
-    if (DeprecatedString::formatted("{} FAIL {}", 1, 2) != "1 FAIL 2") {
+    if (ByteString::formatted("{} FAIL {}", 1, 2) != "1 FAIL 2") {
         fprintf(stderr, "FAIL\n");
         exit(1);
     }
@@ -202,13 +202,13 @@ TEST_CASE(ensure_that_format_works)
 TEST_CASE(format_string_literal_as_pointer)
 {
     char const* literal = "abc";
-    EXPECT_EQ(DeprecatedString::formatted("{:p}", literal), DeprecatedString::formatted("{:p}", reinterpret_cast<FlatPtr>(literal)));
+    EXPECT_EQ(ByteString::formatted("{:p}", literal), ByteString::formatted("{:p}", reinterpret_cast<FlatPtr>(literal)));
 }
 
 TEST_CASE(format_character)
 {
     char a = 'a';
-    EXPECT_EQ(DeprecatedString::formatted("{}", true ? a : 'b'), "a");
+    EXPECT_EQ(ByteString::formatted("{}", true ? a : 'b'), "a");
 }
 
 struct A {
@@ -225,8 +225,8 @@ struct AK::Formatter<B> : Formatter<StringView> {
 
 TEST_CASE(format_if_supported)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{}", FormatIfSupported { A {} }), "?");
-    EXPECT_EQ(DeprecatedString::formatted("{}", FormatIfSupported { B {} }), "B");
+    EXPECT_EQ(ByteString::formatted("{}", FormatIfSupported { A {} }), "?");
+    EXPECT_EQ(ByteString::formatted("{}", FormatIfSupported { B {} }), "B");
 }
 
 TEST_CASE(file_descriptor)
@@ -254,39 +254,39 @@ TEST_CASE(file_descriptor)
 
 TEST_CASE(floating_point_numbers)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{}", 1.12), "1.12");
-    EXPECT_EQ(DeprecatedString::formatted("{}", 1.), "1");
-    EXPECT_EQ(DeprecatedString::formatted("{:.3}", 1.12), "1.12");
-    EXPECT_EQ(DeprecatedString::formatted("{:.1}", 1.12), "1.1");
-    EXPECT_EQ(DeprecatedString::formatted("{}", -1.12), "-1.12");
-    EXPECT_EQ(DeprecatedString::formatted("{:'.4}", 1234.5678), "1,234.5678");
-    EXPECT_EQ(DeprecatedString::formatted("{:'.4}", -1234.5678), "-1,234.5678");
+    EXPECT_EQ(ByteString::formatted("{}", 1.12), "1.12");
+    EXPECT_EQ(ByteString::formatted("{}", 1.), "1");
+    EXPECT_EQ(ByteString::formatted("{:.3}", 1.12), "1.12");
+    EXPECT_EQ(ByteString::formatted("{:.1}", 1.12), "1.1");
+    EXPECT_EQ(ByteString::formatted("{}", -1.12), "-1.12");
+    EXPECT_EQ(ByteString::formatted("{:'.4}", 1234.5678), "1,234.5678");
+    EXPECT_EQ(ByteString::formatted("{:'.4}", -1234.5678), "-1,234.5678");
 
-    EXPECT_EQ(DeprecatedString::formatted("{:.30f}", 1.0), "1.000000000000000000000000000000");
-    EXPECT_EQ(DeprecatedString::formatted("{:.30f}", 1.5), "1.500000000000000000000000000000");
-    EXPECT_EQ(DeprecatedString::formatted("{:.30f}", -2.0), "-2.000000000000000000000000000000");
+    EXPECT_EQ(ByteString::formatted("{:.30f}", 1.0), "1.000000000000000000000000000000");
+    EXPECT_EQ(ByteString::formatted("{:.30f}", 1.5), "1.500000000000000000000000000000");
+    EXPECT_EQ(ByteString::formatted("{:.30f}", -2.0), "-2.000000000000000000000000000000");
 
-    EXPECT_EQ(DeprecatedString::formatted("{:.0f}", 1.4), "1");
-    EXPECT_EQ(DeprecatedString::formatted("{:.0f}", 1.5), "2");
-    EXPECT_EQ(DeprecatedString::formatted("{:.0f}", -1.9), "-2");
+    EXPECT_EQ(ByteString::formatted("{:.0f}", 1.4), "1");
+    EXPECT_EQ(ByteString::formatted("{:.0f}", 1.5), "2");
+    EXPECT_EQ(ByteString::formatted("{:.0f}", -1.9), "-2");
 
-    EXPECT_EQ(DeprecatedString::formatted("{:.1f}", 1.4), "1.4");
-    EXPECT_EQ(DeprecatedString::formatted("{:.1f}", 1.99), "2.0");
-    EXPECT_EQ(DeprecatedString::formatted("{:.1f}", 9.999), "10.0");
+    EXPECT_EQ(ByteString::formatted("{:.1f}", 1.4), "1.4");
+    EXPECT_EQ(ByteString::formatted("{:.1f}", 1.99), "2.0");
+    EXPECT_EQ(ByteString::formatted("{:.1f}", 9.999), "10.0");
 
-    EXPECT_EQ(DeprecatedString::formatted("{}", NAN), "nan");
-    EXPECT_EQ(DeprecatedString::formatted("{}", INFINITY), "inf");
-    EXPECT_EQ(DeprecatedString::formatted("{}", -INFINITY), "-inf");
+    EXPECT_EQ(ByteString::formatted("{}", NAN), "nan");
+    EXPECT_EQ(ByteString::formatted("{}", INFINITY), "inf");
+    EXPECT_EQ(ByteString::formatted("{}", -INFINITY), "-inf");
 
     // FIXME: There is always the question what we mean with the width field. Do we mean significant digits?
     //        Do we mean the whole width? This is what was the simplest to implement:
-    EXPECT_EQ(DeprecatedString::formatted("{:x>5.1}", 1.12), "xx1.1");
+    EXPECT_EQ(ByteString::formatted("{:x>5.1}", 1.12), "xx1.1");
 }
 
 TEST_CASE(floating_point_default_precision)
 {
 #define EXPECT_FORMAT(lit, value) \
-    EXPECT_EQ(DeprecatedString::formatted("{}", lit), value##sv)
+    EXPECT_EQ(ByteString::formatted("{}", lit), value##sv)
 
     EXPECT_FORMAT(10.3f, "10.3");
     EXPECT_FORMAT(123e4f, "1230000");
@@ -307,24 +307,24 @@ TEST_CASE(floating_point_default_precision)
 
 TEST_CASE(no_precision_no_trailing_number)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:.0}", 0.1), "0");
+    EXPECT_EQ(ByteString::formatted("{:.0}", 0.1), "0");
 }
 
 TEST_CASE(precision_with_trailing_zeros)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:0.3}", 1.12), "1.120");
-    EXPECT_EQ(DeprecatedString::formatted("{:0.1}", 1.12), "1.1");
+    EXPECT_EQ(ByteString::formatted("{:0.3}", 1.12), "1.120");
+    EXPECT_EQ(ByteString::formatted("{:0.1}", 1.12), "1.1");
 }
 
 TEST_CASE(magnitude_less_than_zero)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{}", -0.654), "-0.654");
-    EXPECT_EQ(DeprecatedString::formatted("{}", 0.654), "0.654");
+    EXPECT_EQ(ByteString::formatted("{}", -0.654), "-0.654");
+    EXPECT_EQ(ByteString::formatted("{}", 0.654), "0.654");
 }
 
 TEST_CASE(format_nullptr)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{}", nullptr), DeprecatedString::formatted("{:p}", static_cast<FlatPtr>(0)));
+    EXPECT_EQ(ByteString::formatted("{}", nullptr), ByteString::formatted("{:p}", static_cast<FlatPtr>(0)));
 }
 
 struct C {
@@ -340,12 +340,12 @@ struct AK::Formatter<C> : AK::Formatter<FormatString> {
 
 TEST_CASE(use_format_string_formatter)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:*<10}", C { 42 }), "C(i=42)***");
+    EXPECT_EQ(ByteString::formatted("{:*<10}", C { 42 }), "C(i=42)***");
 }
 
 TEST_CASE(long_long_regression)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{}", 0x0123456789abcdefLL), "81985529216486895");
+    EXPECT_EQ(ByteString::formatted("{}", 0x0123456789abcdefLL), "81985529216486895");
 
     StringBuilder builder;
     AK::FormatBuilder fmtbuilder { builder };
@@ -356,28 +356,28 @@ TEST_CASE(long_long_regression)
 
 TEST_CASE(hex_dump)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{:hex-dump}", "0000"), "30303030");
-    EXPECT_EQ(DeprecatedString::formatted("{:>4hex-dump}", "0000"), "30303030    0000");
-    EXPECT_EQ(DeprecatedString::formatted("{:>2hex-dump}", "0000"), "3030    00\n3030    00");
-    EXPECT_EQ(DeprecatedString::formatted("{:*>4hex-dump}", "0000"), "30303030****0000");
+    EXPECT_EQ(ByteString::formatted("{:hex-dump}", "0000"), "30303030");
+    EXPECT_EQ(ByteString::formatted("{:>4hex-dump}", "0000"), "30303030    0000");
+    EXPECT_EQ(ByteString::formatted("{:>2hex-dump}", "0000"), "3030    00\n3030    00");
+    EXPECT_EQ(ByteString::formatted("{:*>4hex-dump}", "0000"), "30303030****0000");
 }
 
 TEST_CASE(span_format)
 {
     {
         Vector<int> v { 1, 2, 3, 4 };
-        EXPECT_EQ(DeprecatedString::formatted("{}", v.span()), "[ 1, 2, 3, 4 ]");
-        EXPECT_EQ(DeprecatedString::formatted("{}", const_cast<AddConst<decltype(v)>&>(v).span()), "[ 1, 2, 3, 4 ]");
+        EXPECT_EQ(ByteString::formatted("{}", v.span()), "[ 1, 2, 3, 4 ]");
+        EXPECT_EQ(ByteString::formatted("{}", const_cast<AddConst<decltype(v)>&>(v).span()), "[ 1, 2, 3, 4 ]");
     }
     {
         Vector<StringView> v { "1"sv, "2"sv, "3"sv, "4"sv };
-        EXPECT_EQ(DeprecatedString::formatted("{}", v.span()), "[ 1, 2, 3, 4 ]");
-        EXPECT_EQ(DeprecatedString::formatted("{}", const_cast<AddConst<decltype(v)>&>(v).span()), "[ 1, 2, 3, 4 ]");
+        EXPECT_EQ(ByteString::formatted("{}", v.span()), "[ 1, 2, 3, 4 ]");
+        EXPECT_EQ(ByteString::formatted("{}", const_cast<AddConst<decltype(v)>&>(v).span()), "[ 1, 2, 3, 4 ]");
     }
     {
-        Vector<Vector<DeprecatedString>> v { { "1"sv, "2"sv }, { "3"sv, "4"sv } };
-        EXPECT_EQ(DeprecatedString::formatted("{}", v.span()), "[ [ 1, 2 ], [ 3, 4 ] ]");
-        EXPECT_EQ(DeprecatedString::formatted("{}", const_cast<AddConst<decltype(v)>&>(v).span()), "[ [ 1, 2 ], [ 3, 4 ] ]");
+        Vector<Vector<ByteString>> v { { "1"sv, "2"sv }, { "3"sv, "4"sv } };
+        EXPECT_EQ(ByteString::formatted("{}", v.span()), "[ [ 1, 2 ], [ 3, 4 ] ]");
+        EXPECT_EQ(ByteString::formatted("{}", const_cast<AddConst<decltype(v)>&>(v).span()), "[ [ 1, 2 ], [ 3, 4 ] ]");
     }
 }
 
@@ -385,28 +385,28 @@ TEST_CASE(vector_format)
 {
     {
         Vector<int> v { 1, 2, 3, 4 };
-        EXPECT_EQ(DeprecatedString::formatted("{}", v), "[ 1, 2, 3, 4 ]");
+        EXPECT_EQ(ByteString::formatted("{}", v), "[ 1, 2, 3, 4 ]");
     }
     {
         Vector<StringView> v { "1"sv, "2"sv, "3"sv, "4"sv };
-        EXPECT_EQ(DeprecatedString::formatted("{}", v), "[ 1, 2, 3, 4 ]");
+        EXPECT_EQ(ByteString::formatted("{}", v), "[ 1, 2, 3, 4 ]");
     }
     {
-        Vector<Vector<DeprecatedString>> v { { "1"sv, "2"sv }, { "3"sv, "4"sv } };
-        EXPECT_EQ(DeprecatedString::formatted("{}", v), "[ [ 1, 2 ], [ 3, 4 ] ]");
+        Vector<Vector<ByteString>> v { { "1"sv, "2"sv }, { "3"sv, "4"sv } };
+        EXPECT_EQ(ByteString::formatted("{}", v), "[ [ 1, 2 ], [ 3, 4 ] ]");
     }
 }
 
 TEST_CASE(format_wchar)
 {
-    EXPECT_EQ(DeprecatedString::formatted("{}", L'a'), "a");
-    EXPECT_EQ(DeprecatedString::formatted("{}", L'\U0001F41E'), "\xF0\x9F\x90\x9E");
-    EXPECT_EQ(DeprecatedString::formatted("{:x}", L'a'), "61");
-    EXPECT_EQ(DeprecatedString::formatted("{:x}", L'\U0001F41E'), "1f41e");
-    EXPECT_EQ(DeprecatedString::formatted("{:d}", L'a'), "97");
-    EXPECT_EQ(DeprecatedString::formatted("{:d}", L'\U0001F41E'), "128030");
+    EXPECT_EQ(ByteString::formatted("{}", L'a'), "a");
+    EXPECT_EQ(ByteString::formatted("{}", L'\U0001F41E'), "\xF0\x9F\x90\x9E");
+    EXPECT_EQ(ByteString::formatted("{:x}", L'a'), "61");
+    EXPECT_EQ(ByteString::formatted("{:x}", L'\U0001F41E'), "1f41e");
+    EXPECT_EQ(ByteString::formatted("{:d}", L'a'), "97");
+    EXPECT_EQ(ByteString::formatted("{:d}", L'\U0001F41E'), "128030");
 
-    EXPECT_EQ(DeprecatedString::formatted("{:6}", L'a'), "a     ");
-    EXPECT_EQ(DeprecatedString::formatted("{:6d}", L'a'), "    97");
-    EXPECT_EQ(DeprecatedString::formatted("{:#x}", L'\U0001F41E'), "0x1f41e");
+    EXPECT_EQ(ByteString::formatted("{:6}", L'a'), "a     ");
+    EXPECT_EQ(ByteString::formatted("{:6d}", L'a'), "    97");
+    EXPECT_EQ(ByteString::formatted("{:#x}", L'\U0001F41E'), "0x1f41e");
 }
diff --git a/Tests/AK/TestHashMap.cpp b/Tests/AK/TestHashMap.cpp
index df7c5560a89..776e8e48bff 100644
--- a/Tests/AK/TestHashMap.cpp
+++ b/Tests/AK/TestHashMap.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/String.h>
@@ -20,7 +20,7 @@ TEST_CASE(construct)
 
 TEST_CASE(construct_from_initializer_list)
 {
-    HashMap<int, DeprecatedString> number_to_string {
+    HashMap<int, ByteString> number_to_string {
         { 1, "One" },
         { 2, "Two" },
         { 3, "Three" },
@@ -31,7 +31,7 @@ TEST_CASE(construct_from_initializer_list)
 
 TEST_CASE(populate)
 {
-    HashMap<int, DeprecatedString> number_to_string;
+    HashMap<int, ByteString> number_to_string;
     number_to_string.set(1, "One");
     number_to_string.set(2, "Two");
     number_to_string.set(3, "Three");
@@ -42,7 +42,7 @@ TEST_CASE(populate)
 
 TEST_CASE(range_loop)
 {
-    HashMap<int, DeprecatedString> number_to_string;
+    HashMap<int, ByteString> number_to_string;
     EXPECT_EQ(number_to_string.set(1, "One"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(number_to_string.set(2, "Two"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(number_to_string.set(3, "Three"), AK::HashSetResult::InsertedNewEntry);
@@ -57,7 +57,7 @@ TEST_CASE(range_loop)
 
 TEST_CASE(map_remove)
 {
-    HashMap<int, DeprecatedString> number_to_string;
+    HashMap<int, ByteString> number_to_string;
     EXPECT_EQ(number_to_string.set(1, "One"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(number_to_string.set(2, "Two"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(number_to_string.set(3, "Three"), AK::HashSetResult::InsertedNewEntry);
@@ -74,7 +74,7 @@ TEST_CASE(map_remove)
 
 TEST_CASE(remove_all_matching)
 {
-    HashMap<int, DeprecatedString> map;
+    HashMap<int, ByteString> map;
 
     map.set(1, "One");
     map.set(2, "Two");
@@ -83,27 +83,27 @@ TEST_CASE(remove_all_matching)
 
     EXPECT_EQ(map.size(), 4u);
 
-    EXPECT_EQ(map.remove_all_matching([&](int key, DeprecatedString const& value) { return key == 1 || value == "Two"; }), true);
+    EXPECT_EQ(map.remove_all_matching([&](int key, ByteString const& value) { return key == 1 || value == "Two"; }), true);
     EXPECT_EQ(map.size(), 2u);
 
-    EXPECT_EQ(map.remove_all_matching([&](int, DeprecatedString const&) { return false; }), false);
+    EXPECT_EQ(map.remove_all_matching([&](int, ByteString const&) { return false; }), false);
     EXPECT_EQ(map.size(), 2u);
 
     EXPECT(map.contains(3));
     EXPECT(map.contains(4));
 
-    EXPECT_EQ(map.remove_all_matching([&](int, DeprecatedString const&) { return true; }), true);
-    EXPECT_EQ(map.remove_all_matching([&](int, DeprecatedString const&) { return false; }), false);
+    EXPECT_EQ(map.remove_all_matching([&](int, ByteString const&) { return true; }), true);
+    EXPECT_EQ(map.remove_all_matching([&](int, ByteString const&) { return false; }), false);
 
     EXPECT(map.is_empty());
 
-    EXPECT_EQ(map.remove_all_matching([&](int, DeprecatedString const&) { return true; }), false);
+    EXPECT_EQ(map.remove_all_matching([&](int, ByteString const&) { return true; }), false);
 }
 
 TEST_CASE(case_insensitive)
 {
-    HashMap<DeprecatedString, int, CaseInsensitiveStringTraits> casemap;
-    EXPECT_EQ(DeprecatedString("nickserv").to_lowercase(), DeprecatedString("NickServ").to_lowercase());
+    HashMap<ByteString, int, CaseInsensitiveStringTraits> casemap;
+    EXPECT_EQ(ByteString("nickserv").to_lowercase(), ByteString("NickServ").to_lowercase());
     EXPECT_EQ(casemap.set("nickserv", 3), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(casemap.set("NickServ", 3), AK::HashSetResult::ReplacedExistingEntry);
     EXPECT_EQ(casemap.size(), 1u);
@@ -120,11 +120,11 @@ TEST_CASE(case_insensitive_stringview)
 TEST_CASE(hashmap_of_nonnullownptr_get)
 {
     struct Object {
-        Object(DeprecatedString const& s)
+        Object(ByteString const& s)
             : string(s)
         {
         }
-        DeprecatedString string;
+        ByteString string;
     };
 
     HashMap<int, NonnullOwnPtr<Object>> objects;
@@ -151,16 +151,16 @@ TEST_CASE(hashmap_of_nonnullownptr_get)
 
 TEST_CASE(many_strings)
 {
-    HashMap<DeprecatedString, int> strings;
+    HashMap<ByteString, int> strings;
     for (int i = 0; i < 999; ++i) {
-        EXPECT_EQ(strings.set(DeprecatedString::number(i), i), AK::HashSetResult::InsertedNewEntry);
+        EXPECT_EQ(strings.set(ByteString::number(i), i), AK::HashSetResult::InsertedNewEntry);
     }
     EXPECT_EQ(strings.size(), 999u);
     for (auto& it : strings) {
         EXPECT_EQ(it.key.to_int().value(), it.value);
     }
     for (int i = 0; i < 999; ++i) {
-        EXPECT_EQ(strings.remove(DeprecatedString::number(i)), true);
+        EXPECT_EQ(strings.remove(ByteString::number(i)), true);
     }
     EXPECT_EQ(strings.is_empty(), true);
 }
@@ -213,7 +213,7 @@ TEST_CASE(basic_contains)
 
 TEST_CASE(in_place_rehashing_ordered_loop_bug)
 {
-    OrderedHashMap<DeprecatedString, DeprecatedString> map;
+    OrderedHashMap<ByteString, ByteString> map;
     map.set("yt.innertube::nextId", "");
     map.set("yt.innertube::requests", "");
     map.remove("yt.innertube::nextId");
diff --git a/Tests/AK/TestHashTable.cpp b/Tests/AK/TestHashTable.cpp
index d1ca5d1788c..fd75f4e5a29 100644
--- a/Tests/AK/TestHashTable.cpp
+++ b/Tests/AK/TestHashTable.cpp
@@ -7,7 +7,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashTable.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/Vector.h>
@@ -46,7 +46,7 @@ TEST_CASE(move_is_not_swap)
 
 TEST_CASE(populate)
 {
-    HashTable<DeprecatedString> strings;
+    HashTable<ByteString> strings;
     strings.set("One");
     strings.set("Two");
     strings.set("Three");
@@ -57,7 +57,7 @@ TEST_CASE(populate)
 
 TEST_CASE(range_loop)
 {
-    HashTable<DeprecatedString> strings;
+    HashTable<ByteString> strings;
     EXPECT_EQ(strings.set("One"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(strings.set("Two"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(strings.set("Three"), AK::HashSetResult::InsertedNewEntry);
@@ -73,7 +73,7 @@ TEST_CASE(range_loop)
 TEST_CASE(range_loop_reverse)
 {
     Array strings = { "One"sv, "Two"sv, "Three"sv };
-    OrderedHashTable<DeprecatedString> table;
+    OrderedHashTable<ByteString> table;
     EXPECT_EQ(table.set(strings[0]), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(table.set(strings[1]), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(table.set(strings[2]), AK::HashSetResult::InsertedNewEntry);
@@ -90,7 +90,7 @@ TEST_CASE(range_loop_reverse)
 
 TEST_CASE(table_remove)
 {
-    HashTable<DeprecatedString> strings;
+    HashTable<ByteString> strings;
     EXPECT_EQ(strings.set("One"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(strings.set("Two"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(strings.set("Three"), AK::HashSetResult::InsertedNewEntry);
@@ -133,8 +133,8 @@ TEST_CASE(remove_all_matching)
 
 TEST_CASE(case_insensitive)
 {
-    HashTable<DeprecatedString, CaseInsensitiveStringTraits> casetable;
-    EXPECT_EQ(DeprecatedString("nickserv").to_lowercase(), DeprecatedString("NickServ").to_lowercase());
+    HashTable<ByteString, CaseInsensitiveStringTraits> casetable;
+    EXPECT_EQ(ByteString("nickserv").to_lowercase(), ByteString("NickServ").to_lowercase());
     EXPECT_EQ(casetable.set("nickserv"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(casetable.set("NickServ"), AK::HashSetResult::ReplacedExistingEntry);
     EXPECT_EQ(casetable.size(), 1u);
@@ -142,33 +142,33 @@ TEST_CASE(case_insensitive)
 
 TEST_CASE(many_strings)
 {
-    HashTable<DeprecatedString> strings;
+    HashTable<ByteString> strings;
     for (int i = 0; i < 999; ++i) {
-        EXPECT_EQ(strings.set(DeprecatedString::number(i)), AK::HashSetResult::InsertedNewEntry);
+        EXPECT_EQ(strings.set(ByteString::number(i)), AK::HashSetResult::InsertedNewEntry);
     }
     EXPECT_EQ(strings.size(), 999u);
     for (int i = 0; i < 999; ++i) {
-        EXPECT_EQ(strings.remove(DeprecatedString::number(i)), true);
+        EXPECT_EQ(strings.remove(ByteString::number(i)), true);
     }
     EXPECT_EQ(strings.is_empty(), true);
 }
 
 TEST_CASE(many_collisions)
 {
-    struct StringCollisionTraits : public DefaultTraits<DeprecatedString> {
-        static unsigned hash(DeprecatedString const&) { return 0; }
+    struct StringCollisionTraits : public DefaultTraits<ByteString> {
+        static unsigned hash(ByteString const&) { return 0; }
     };
 
-    HashTable<DeprecatedString, StringCollisionTraits> strings;
+    HashTable<ByteString, StringCollisionTraits> strings;
     for (int i = 0; i < 999; ++i) {
-        EXPECT_EQ(strings.set(DeprecatedString::number(i)), AK::HashSetResult::InsertedNewEntry);
+        EXPECT_EQ(strings.set(ByteString::number(i)), AK::HashSetResult::InsertedNewEntry);
     }
 
     EXPECT_EQ(strings.set("foo"), AK::HashSetResult::InsertedNewEntry);
     EXPECT_EQ(strings.size(), 1000u);
 
     for (int i = 0; i < 999; ++i) {
-        EXPECT_EQ(strings.remove(DeprecatedString::number(i)), true);
+        EXPECT_EQ(strings.remove(ByteString::number(i)), true);
     }
 
     EXPECT(strings.find("foo") != strings.end());
@@ -176,24 +176,24 @@ TEST_CASE(many_collisions)
 
 TEST_CASE(space_reuse)
 {
-    struct StringCollisionTraits : public DefaultTraits<DeprecatedString> {
-        static unsigned hash(DeprecatedString const&) { return 0; }
+    struct StringCollisionTraits : public DefaultTraits<ByteString> {
+        static unsigned hash(ByteString const&) { return 0; }
     };
 
-    HashTable<DeprecatedString, StringCollisionTraits> strings;
+    HashTable<ByteString, StringCollisionTraits> strings;
 
     // Add a few items to allow it to do initial resizing.
     EXPECT_EQ(strings.set("0"), AK::HashSetResult::InsertedNewEntry);
     for (int i = 1; i < 5; ++i) {
-        EXPECT_EQ(strings.set(DeprecatedString::number(i)), AK::HashSetResult::InsertedNewEntry);
-        EXPECT_EQ(strings.remove(DeprecatedString::number(i - 1)), true);
+        EXPECT_EQ(strings.set(ByteString::number(i)), AK::HashSetResult::InsertedNewEntry);
+        EXPECT_EQ(strings.remove(ByteString::number(i - 1)), true);
     }
 
     auto capacity = strings.capacity();
 
     for (int i = 5; i < 999; ++i) {
-        EXPECT_EQ(strings.set(DeprecatedString::number(i)), AK::HashSetResult::InsertedNewEntry);
-        EXPECT_EQ(strings.remove(DeprecatedString::number(i - 1)), true);
+        EXPECT_EQ(strings.set(ByteString::number(i)), AK::HashSetResult::InsertedNewEntry);
+        EXPECT_EQ(strings.remove(ByteString::number(i - 1)), true);
     }
 
     EXPECT_EQ(strings.capacity(), capacity);
@@ -301,7 +301,7 @@ TEST_CASE(doubles)
 
 TEST_CASE(reinsertion)
 {
-    OrderedHashTable<DeprecatedString> map;
+    OrderedHashTable<ByteString> map;
     map.set("ytidb::LAST_RESULT_ENTRY_KEY");
     map.set("__sak");
     map.remove("__sak");
@@ -445,7 +445,7 @@ TEST_CASE(ordered_remove_from_head)
 
 TEST_CASE(ordered_infinite_loop_clang_regression)
 {
-    OrderedHashTable<DeprecatedString> map;
+    OrderedHashTable<ByteString> map;
     map.set("");
     map.set("1");
     map.set("_cb");
diff --git a/Tests/AK/TestIPv4Address.cpp b/Tests/AK/TestIPv4Address.cpp
index aaac975daa3..e352db12b17 100644
--- a/Tests/AK/TestIPv4Address.cpp
+++ b/Tests/AK/TestIPv4Address.cpp
@@ -61,7 +61,7 @@ TEST_CASE(should_convert_to_string)
 {
     constexpr IPv4Address addr(1, 25, 39, 42);
 
-    EXPECT_EQ("1.25.39.42", addr.to_deprecated_string());
+    EXPECT_EQ("1.25.39.42", addr.to_byte_string());
 }
 
 TEST_CASE(should_make_ipv4_address_from_string)
diff --git a/Tests/AK/TestJSON.cpp b/Tests/AK/TestJSON.cpp
index 7527868ae7e..906c4f03570 100644
--- a/Tests/AK/TestJSON.cpp
+++ b/Tests/AK/TestJSON.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonValue.h>
@@ -14,7 +14,7 @@
 
 TEST_CASE(load_form)
 {
-    DeprecatedString raw_form_json = R"(
+    ByteString raw_form_json = R"(
     {
         "name": "Form1",
         "widgets": [
@@ -40,7 +40,7 @@ TEST_CASE(load_form)
 
     EXPECT(form_json.is_object());
 
-    auto name = form_json.as_object().get_deprecated_string("name"sv);
+    auto name = form_json.as_object().get_byte_string("name"sv);
     EXPECT(name.has_value());
 
     EXPECT_EQ(name.value(), "Form1");
@@ -50,7 +50,7 @@ TEST_CASE(load_form)
 
     widgets->for_each([&](JsonValue const& widget_value) {
         auto& widget_object = widget_value.as_object();
-        auto widget_class = widget_object.get_deprecated_string("class"sv).value();
+        auto widget_class = widget_object.get_byte_string("class"sv).value();
         widget_object.for_each_member([&]([[maybe_unused]] auto& property_name, [[maybe_unused]] const JsonValue& property_value) {
         });
     });
@@ -109,13 +109,13 @@ TEST_CASE(json_duplicate_keys)
     json.set("test", "foo");
     json.set("test", "bar");
     json.set("test", "baz");
-    EXPECT_EQ(json.to_deprecated_string(), "{\"test\":\"baz\"}");
+    EXPECT_EQ(json.to_byte_string(), "{\"test\":\"baz\"}");
 }
 
 TEST_CASE(json_u64_roundtrip)
 {
     auto big_value = 0xffffffffffffffffull;
-    auto json = JsonValue(big_value).to_deprecated_string();
+    auto json = JsonValue(big_value).to_byte_string();
     auto value = JsonValue::from_string(json);
     EXPECT_EQ_FORCE(value.is_error(), false);
     EXPECT_EQ(value.value().as_u64(), big_value);
@@ -292,7 +292,7 @@ private:
 
 TEST_CASE(fallible_json_object_for_each)
 {
-    DeprecatedString raw_json = R"(
+    ByteString raw_json = R"(
     {
         "name": "anon",
         "home": "/home/anon",
@@ -332,7 +332,7 @@ TEST_CASE(fallible_json_object_for_each)
 
 TEST_CASE(fallible_json_array_for_each)
 {
-    DeprecatedString raw_json = R"(
+    ByteString raw_json = R"(
     [
         "anon",
         "/home/anon",
@@ -489,7 +489,7 @@ TEST_CASE(json_array_serialize)
     auto array = json_value.as_array();
     StringBuilder builder {};
     array.serialize(builder);
-    EXPECT_EQ(builder.to_deprecated_string(), raw_json);
+    EXPECT_EQ(builder.to_byte_string(), raw_json);
 }
 
 TEST_CASE(json_array_values)
diff --git a/Tests/AK/TestLexicalPath.cpp b/Tests/AK/TestLexicalPath.cpp
index 23875af3d9a..b81d0147c18 100644
--- a/Tests/AK/TestLexicalPath.cpp
+++ b/Tests/AK/TestLexicalPath.cpp
@@ -7,7 +7,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 
 TEST_CASE(relative_path)
diff --git a/Tests/AK/TestMACAddress.cpp b/Tests/AK/TestMACAddress.cpp
index 04e0a72282d..dd1a347f52e 100644
--- a/Tests/AK/TestMACAddress.cpp
+++ b/Tests/AK/TestMACAddress.cpp
@@ -80,7 +80,7 @@ TEST_CASE(should_equality_compare)
 TEST_CASE(should_string_format)
 {
     MACAddress sut(1, 2, 3, 4, 5, 6);
-    EXPECT_EQ("01:02:03:04:05:06", sut.to_deprecated_string());
+    EXPECT_EQ("01:02:03:04:05:06", sut.to_byte_string());
 }
 
 TEST_CASE(should_make_mac_address_from_string_numbers)
diff --git a/Tests/AK/TestMemory.cpp b/Tests/AK/TestMemory.cpp
index b1a17caa6ef..9ee9d4e69e4 100644
--- a/Tests/AK/TestMemory.cpp
+++ b/Tests/AK/TestMemory.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/MemMem.h>
 #include <AK/Memory.h>
 
@@ -78,9 +78,9 @@ TEST_CASE(kmp_two_chunks)
 
 TEST_CASE(timing_safe_compare)
 {
-    DeprecatedString data_set = "abcdefghijklmnopqrstuvwxyz123456789";
+    ByteString data_set = "abcdefghijklmnopqrstuvwxyz123456789";
     EXPECT_EQ(true, AK::timing_safe_compare(data_set.characters(), data_set.characters(), data_set.length()));
 
-    DeprecatedString reversed = data_set.reverse();
+    ByteString reversed = data_set.reverse();
     EXPECT_EQ(false, AK::timing_safe_compare(data_set.characters(), reversed.characters(), reversed.length()));
 }
diff --git a/Tests/AK/TestNonnullOwnPtr.cpp b/Tests/AK/TestNonnullOwnPtr.cpp
index 233c65fa6ee..bc37322937a 100644
--- a/Tests/AK/TestNonnullOwnPtr.cpp
+++ b/Tests/AK/TestNonnullOwnPtr.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/OwnPtr.h>
 #include <AK/String.h>
diff --git a/Tests/AK/TestNonnullRefPtr.cpp b/Tests/AK/TestNonnullRefPtr.cpp
index 60621b4b487..268f5abcb12 100644
--- a/Tests/AK/TestNonnullRefPtr.cpp
+++ b/Tests/AK/TestNonnullRefPtr.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/OwnPtr.h>
 
diff --git a/Tests/AK/TestOptional.cpp b/Tests/AK/TestOptional.cpp
index 99c1da21532..5c75b5b84cd 100644
--- a/Tests/AK/TestOptional.cpp
+++ b/Tests/AK/TestOptional.cpp
@@ -7,7 +7,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <AK/Vector.h>
 
@@ -59,7 +59,7 @@ TEST_CASE(optional_rvalue_ref_qualified_getters)
 TEST_CASE(optional_leak_1)
 {
     struct Structure {
-        Optional<DeprecatedString> str;
+        Optional<ByteString> str;
     };
 
     // This used to leak, it does not anymore.
@@ -81,7 +81,7 @@ TEST_CASE(comparison_without_values)
 {
     Optional<StringView> opt0;
     Optional<StringView> opt1;
-    Optional<DeprecatedString> opt2;
+    Optional<ByteString> opt2;
     EXPECT_EQ(opt0, opt1);
     EXPECT_EQ(opt0, opt2);
 }
@@ -90,7 +90,7 @@ TEST_CASE(comparison_with_values)
 {
     Optional<StringView> opt0;
     Optional<StringView> opt1 = "foo"sv;
-    Optional<DeprecatedString> opt2 = "foo"sv;
+    Optional<ByteString> opt2 = "foo"sv;
     Optional<StringView> opt3 = "bar"sv;
     EXPECT_NE(opt0, opt1);
     EXPECT_EQ(opt1, opt2);
@@ -99,14 +99,14 @@ TEST_CASE(comparison_with_values)
 
 TEST_CASE(comparison_to_underlying_types)
 {
-    Optional<DeprecatedString> opt0;
-    EXPECT_NE(opt0, DeprecatedString());
+    Optional<ByteString> opt0;
+    EXPECT_NE(opt0, ByteString());
     EXPECT_NE(opt0, "foo");
 
     Optional<StringView> opt1 = "foo"sv;
     EXPECT_EQ(opt1, "foo");
     EXPECT_NE(opt1, "bar");
-    EXPECT_EQ(opt1, DeprecatedString("foo"));
+    EXPECT_EQ(opt1, ByteString("foo"));
 }
 
 TEST_CASE(comparison_with_numeric_types)
@@ -262,7 +262,7 @@ TEST_CASE(comparison_reference)
     StringView test = "foo"sv;
     Optional<StringView&> opt0;
     Optional<StringView const&> opt1 = test;
-    Optional<DeprecatedString> opt2 = "foo"sv;
+    Optional<ByteString> opt2 = "foo"sv;
     Optional<StringView> opt3 = "bar"sv;
 
     EXPECT_NE(opt0, opt1);
diff --git a/Tests/AK/TestQueue.cpp b/Tests/AK/TestQueue.cpp
index 2e527925c84..25384bc1bdb 100644
--- a/Tests/AK/TestQueue.cpp
+++ b/Tests/AK/TestQueue.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Queue.h>
 
 TEST_CASE(construct)
@@ -32,7 +32,7 @@ TEST_CASE(populate_int)
 
 TEST_CASE(populate_string)
 {
-    Queue<DeprecatedString> strings;
+    Queue<ByteString> strings;
     strings.enqueue("ABC");
     strings.enqueue("DEF");
     EXPECT_EQ(strings.size(), 2u);
@@ -43,11 +43,11 @@ TEST_CASE(populate_string)
 
 TEST_CASE(order)
 {
-    Queue<DeprecatedString> strings;
+    Queue<ByteString> strings;
     EXPECT(strings.is_empty());
 
     for (size_t i = 0; i < 10000; ++i) {
-        strings.enqueue(DeprecatedString::number(i));
+        strings.enqueue(ByteString::number(i));
         EXPECT_EQ(strings.size(), i + 1);
     }
 
diff --git a/Tests/AK/TestRefPtr.cpp b/Tests/AK/TestRefPtr.cpp
index 20c3e10bec0..6eac893eaa4 100644
--- a/Tests/AK/TestRefPtr.cpp
+++ b/Tests/AK/TestRefPtr.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullRefPtr.h>
 
 struct Object : public RefCounted<Object> {
diff --git a/Tests/AK/TestStack.cpp b/Tests/AK/TestStack.cpp
index a48f43d5968..be19c50721a 100644
--- a/Tests/AK/TestStack.cpp
+++ b/Tests/AK/TestStack.cpp
@@ -26,7 +26,7 @@ TEST_CASE(basic)
 
 TEST_CASE(complex_type)
 {
-    AK::Stack<DeprecatedString, 4> stack;
+    AK::Stack<ByteString, 4> stack;
 
     EXPECT_EQ(stack.is_empty(), true);
     EXPECT(stack.push("Well"));
diff --git a/Tests/AK/TestStringUtils.cpp b/Tests/AK/TestStringUtils.cpp
index d4b0765378e..7339311b79a 100644
--- a/Tests/AK/TestStringUtils.cpp
+++ b/Tests/AK/TestStringUtils.cpp
@@ -22,11 +22,11 @@ TEST_CASE(hash_compatible)
     static_assert(AK::Concepts::HashCompatible<FlyString, String>);
     static_assert(AK::Concepts::HashCompatible<FlyString, StringView>);
 
-    static_assert(AK::Concepts::HashCompatible<DeprecatedString, StringView>);
-    static_assert(AK::Concepts::HashCompatible<DeprecatedString, DeprecatedFlyString>);
-    static_assert(AK::Concepts::HashCompatible<StringView, DeprecatedString>);
+    static_assert(AK::Concepts::HashCompatible<ByteString, StringView>);
+    static_assert(AK::Concepts::HashCompatible<ByteString, DeprecatedFlyString>);
+    static_assert(AK::Concepts::HashCompatible<StringView, ByteString>);
     static_assert(AK::Concepts::HashCompatible<StringView, DeprecatedFlyString>);
-    static_assert(AK::Concepts::HashCompatible<DeprecatedFlyString, DeprecatedString>);
+    static_assert(AK::Concepts::HashCompatible<DeprecatedFlyString, ByteString>);
     static_assert(AK::Concepts::HashCompatible<DeprecatedFlyString, StringView>);
 
     static_assert(AK::Concepts::HashCompatible<StringView, ByteBuffer>);
@@ -328,7 +328,7 @@ TEST_CASE(convert_to_floating_point)
 
 TEST_CASE(ends_with)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     EXPECT(AK::StringUtils::ends_with(test_string, "DEF"sv, CaseSensitivity::CaseSensitive));
     EXPECT(AK::StringUtils::ends_with(test_string, "ABCDEF"sv, CaseSensitivity::CaseSensitive));
     EXPECT(!AK::StringUtils::ends_with(test_string, "ABCDE"sv, CaseSensitivity::CaseSensitive));
@@ -339,7 +339,7 @@ TEST_CASE(ends_with)
 
 TEST_CASE(starts_with)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     EXPECT(AK::StringUtils::starts_with(test_string, "ABC"sv, CaseSensitivity::CaseSensitive));
     EXPECT(AK::StringUtils::starts_with(test_string, "ABCDEF"sv, CaseSensitivity::CaseSensitive));
     EXPECT(!AK::StringUtils::starts_with(test_string, "BCDEF"sv, CaseSensitivity::CaseSensitive));
@@ -350,7 +350,7 @@ TEST_CASE(starts_with)
 
 TEST_CASE(contains)
 {
-    DeprecatedString test_string = "ABCDEFABCXYZ";
+    ByteString test_string = "ABCDEFABCXYZ";
     EXPECT(AK::StringUtils::contains(test_string, "ABC"sv, CaseSensitivity::CaseSensitive));
     EXPECT(AK::StringUtils::contains(test_string, "ABC"sv, CaseSensitivity::CaseInsensitive));
     EXPECT(AK::StringUtils::contains(test_string, "AbC"sv, CaseSensitivity::CaseInsensitive));
@@ -368,7 +368,7 @@ TEST_CASE(contains)
     EXPECT(!AK::StringUtils::contains(test_string, "L"sv, CaseSensitivity::CaseSensitive));
     EXPECT(!AK::StringUtils::contains(test_string, "L"sv, CaseSensitivity::CaseInsensitive));
 
-    DeprecatedString command_palette_bug_string = "Go Go Back";
+    ByteString command_palette_bug_string = "Go Go Back";
     EXPECT(AK::StringUtils::contains(command_palette_bug_string, "Go Back"sv, AK::CaseSensitivity::CaseSensitive));
     EXPECT(AK::StringUtils::contains(command_palette_bug_string, "gO bAcK"sv, AK::CaseSensitivity::CaseInsensitive));
 }
@@ -397,7 +397,7 @@ TEST_CASE(trim)
 
 TEST_CASE(find)
 {
-    DeprecatedString test_string = "1234567";
+    ByteString test_string = "1234567";
     EXPECT_EQ(AK::StringUtils::find(test_string, "1"sv).value_or(1), 0u);
     EXPECT_EQ(AK::StringUtils::find(test_string, "2"sv).value_or(2), 1u);
     EXPECT_EQ(AK::StringUtils::find(test_string, "3"sv).value_or(3), 2u);
diff --git a/Tests/AK/TestStringView.cpp b/Tests/AK/TestStringView.cpp
index bc098bc1378..1487b848301 100644
--- a/Tests/AK/TestStringView.cpp
+++ b/Tests/AK/TestStringView.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 
 TEST_CASE(construct_empty)
@@ -29,8 +29,8 @@ TEST_CASE(view_literal)
 
 TEST_CASE(compare_views)
 {
-    DeprecatedString foo1 = "foo";
-    DeprecatedString foo2 = "foo";
+    ByteString foo1 = "foo";
+    ByteString foo2 = "foo";
     auto view1 = foo1.view();
     auto view2 = foo2.view();
 
@@ -43,7 +43,7 @@ TEST_CASE(compare_views)
 TEST_CASE(string_view_literal_operator)
 {
     StringView literal_view = "foo"sv;
-    DeprecatedString test_string = "foo";
+    ByteString test_string = "foo";
 
     EXPECT_EQ(literal_view.length(), test_string.length());
     EXPECT_EQ(literal_view, test_string);
@@ -51,7 +51,7 @@ TEST_CASE(string_view_literal_operator)
 
 TEST_CASE(starts_with)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     StringView test_string_view = test_string.view();
     EXPECT(test_string_view.starts_with('A'));
     EXPECT(!test_string_view.starts_with('B'));
@@ -64,7 +64,7 @@ TEST_CASE(starts_with)
 
 TEST_CASE(ends_with)
 {
-    DeprecatedString test_string = "ABCDEF";
+    ByteString test_string = "ABCDEF";
     StringView test_string_view = test_string.view();
     EXPECT(test_string_view.ends_with("DEF"sv));
     EXPECT(test_string_view.ends_with('F'));
@@ -78,23 +78,23 @@ TEST_CASE(ends_with)
 
 TEST_CASE(lines)
 {
-    DeprecatedString test_string = "a\rb\nc\r\nd";
+    ByteString test_string = "a\rb\nc\r\nd";
     StringView test_string_view = test_string.view();
     Vector<StringView> test_string_vector = test_string_view.lines();
     EXPECT_EQ(test_string_vector.size(), 4u);
-    EXPECT(test_string_vector.at(0) == DeprecatedString("a"));
-    EXPECT(test_string_vector.at(1) == DeprecatedString("b"));
-    EXPECT(test_string_vector.at(2) == DeprecatedString("c"));
-    EXPECT(test_string_vector.at(3) == DeprecatedString("d"));
+    EXPECT(test_string_vector.at(0) == ByteString("a"));
+    EXPECT(test_string_vector.at(1) == ByteString("b"));
+    EXPECT(test_string_vector.at(2) == ByteString("c"));
+    EXPECT(test_string_vector.at(3) == ByteString("d"));
 
     test_string = "```\nHello there\r\nHello there\n```";
     test_string_view = test_string.view();
     test_string_vector = test_string_view.lines();
     EXPECT_EQ(test_string_vector.size(), 4u);
-    EXPECT(test_string_vector.at(0) == DeprecatedString("```"));
-    EXPECT(test_string_vector.at(1) == DeprecatedString("Hello there"));
-    EXPECT(test_string_vector.at(2) == DeprecatedString("Hello there"));
-    EXPECT(test_string_vector.at(3) == DeprecatedString("```"));
+    EXPECT(test_string_vector.at(0) == ByteString("```"));
+    EXPECT(test_string_vector.at(1) == ByteString("Hello there"));
+    EXPECT(test_string_vector.at(2) == ByteString("Hello there"));
+    EXPECT(test_string_vector.at(3) == ByteString("```"));
 
     test_string = "\n\n\n";
     test_string_view = test_string.view();
diff --git a/Tests/AK/TestTrie.cpp b/Tests/AK/TestTrie.cpp
index c698ae35492..7fbdfb9f664 100644
--- a/Tests/AK/TestTrie.cpp
+++ b/Tests/AK/TestTrie.cpp
@@ -11,12 +11,12 @@
 
 TEST_CASE(normal_behavior)
 {
-    Trie<char, DeprecatedString> dictionary('/', "");
+    Trie<char, ByteString> dictionary('/', "");
     constexpr StringView data[] { "test"sv, "example"sv, "foo"sv, "foobar"sv };
     constexpr size_t total_chars = 18; // root (1), 'test' (4), 'example' (7), 'foo' (3), 'foobar' (3, "foo" already stored).
     for (auto& view : data) {
         auto it = view.begin();
-        MUST(dictionary.insert(it, view.end(), view, [](auto& parent, auto& it) -> Optional<DeprecatedString> { return DeprecatedString::formatted("{}{}", parent.metadata_value(), *it); }));
+        MUST(dictionary.insert(it, view.end(), view, [](auto& parent, auto& it) -> Optional<ByteString> { return ByteString::formatted("{}{}", parent.metadata_value(), *it); }));
     }
 
     size_t i = 0;
diff --git a/Tests/AK/TestTuple.cpp b/Tests/AK/TestTuple.cpp
index 1690f77905f..258c28dc081 100644
--- a/Tests/AK/TestTuple.cpp
+++ b/Tests/AK/TestTuple.cpp
@@ -10,41 +10,41 @@
 
 TEST_CASE(basic)
 {
-    Tuple<int, DeprecatedString> value { 1, "foo" };
+    Tuple<int, ByteString> value { 1, "foo" };
     EXPECT_EQ(value.get<int>(), 1);
-    EXPECT_EQ(value.get<DeprecatedString>(), "foo");
+    EXPECT_EQ(value.get<ByteString>(), "foo");
     EXPECT_EQ(value.get<0>(), 1);
     EXPECT_EQ(value.get<1>(), "foo");
 
     // Move assignment
     value = { 2, "bar" };
     EXPECT_EQ(value.get<int>(), 2);
-    EXPECT_EQ(value.get<DeprecatedString>(), "bar");
+    EXPECT_EQ(value.get<ByteString>(), "bar");
     EXPECT_EQ(value.get<0>(), 2);
     EXPECT_EQ(value.get<1>(), "bar");
 
     // Copy ctor
     auto other_value { value };
     EXPECT_EQ(other_value.get<int>(), 2);
-    EXPECT_EQ(other_value.get<DeprecatedString>(), "bar");
+    EXPECT_EQ(other_value.get<ByteString>(), "bar");
     EXPECT_EQ(other_value.get<0>(), 2);
     EXPECT_EQ(other_value.get<1>(), "bar");
 
     // Move ctor
     auto moved_to_value { move(value) };
     EXPECT_EQ(moved_to_value.get<int>(), 2);
-    EXPECT_EQ(moved_to_value.get<DeprecatedString>(), "bar");
+    EXPECT_EQ(moved_to_value.get<ByteString>(), "bar");
     EXPECT_EQ(moved_to_value.get<0>(), 2);
     EXPECT_EQ(moved_to_value.get<1>(), "bar");
 
     // Copy assignment
     value = moved_to_value;
     EXPECT_EQ(moved_to_value.get<int>(), 2);
-    EXPECT_EQ(moved_to_value.get<DeprecatedString>(), "bar");
+    EXPECT_EQ(moved_to_value.get<ByteString>(), "bar");
     EXPECT_EQ(moved_to_value.get<0>(), 2);
     EXPECT_EQ(moved_to_value.get<1>(), "bar");
     EXPECT_EQ(value.get<int>(), 2);
-    EXPECT_EQ(value.get<DeprecatedString>(), "bar");
+    EXPECT_EQ(value.get<ByteString>(), "bar");
     EXPECT_EQ(value.get<0>(), 2);
     EXPECT_EQ(value.get<1>(), "bar");
 }
@@ -68,12 +68,12 @@ TEST_CASE(no_copy)
 
 TEST_CASE(apply)
 {
-    Tuple<int, int, DeprecatedString> args { 1, 2, "foo" };
+    Tuple<int, int, ByteString> args { 1, 2, "foo" };
 
     // With copy
     {
         bool was_called = false;
-        args.apply_as_args([&](int a, int b, DeprecatedString c) {
+        args.apply_as_args([&](int a, int b, ByteString c) {
             was_called = true;
             EXPECT_EQ(a, 1);
             EXPECT_EQ(b, 2);
@@ -85,7 +85,7 @@ TEST_CASE(apply)
     // With reference
     {
         bool was_called = false;
-        args.apply_as_args([&](int& a, int& b, DeprecatedString& c) {
+        args.apply_as_args([&](int& a, int& b, ByteString& c) {
             was_called = true;
             EXPECT_EQ(a, 1);
             EXPECT_EQ(b, 2);
@@ -98,7 +98,7 @@ TEST_CASE(apply)
     {
         bool was_called = false;
         auto const& args_ref = args;
-        args_ref.apply_as_args([&](int const& a, int const& b, DeprecatedString const& c) {
+        args_ref.apply_as_args([&](int const& a, int const& b, ByteString const& c) {
             was_called = true;
             EXPECT_EQ(a, 1);
             EXPECT_EQ(b, 2);
diff --git a/Tests/AK/TestURL.cpp b/Tests/AK/TestURL.cpp
index 8589c896acd..aed1bf7e6d0 100644
--- a/Tests/AK/TestURL.cpp
+++ b/Tests/AK/TestURL.cpp
@@ -412,21 +412,21 @@ TEST_CASE(leading_whitespace)
 {
     URL url { "   https://foo.com/"sv };
     EXPECT(url.is_valid());
-    EXPECT_EQ(url.to_deprecated_string(), "https://foo.com/");
+    EXPECT_EQ(url.to_byte_string(), "https://foo.com/");
 }
 
 TEST_CASE(trailing_whitespace)
 {
     URL url { "https://foo.com/   "sv };
     EXPECT(url.is_valid());
-    EXPECT_EQ(url.to_deprecated_string(), "https://foo.com/");
+    EXPECT_EQ(url.to_byte_string(), "https://foo.com/");
 }
 
 TEST_CASE(leading_and_trailing_whitespace)
 {
     URL url { "      https://foo.com/   "sv };
     EXPECT(url.is_valid());
-    EXPECT_EQ(url.to_deprecated_string(), "https://foo.com/");
+    EXPECT_EQ(url.to_byte_string(), "https://foo.com/");
 }
 
 TEST_CASE(unicode)
diff --git a/Tests/AK/TestUtf8.cpp b/Tests/AK/TestUtf8.cpp
index 8dcc7d67fb3..bc0d5b24ee3 100644
--- a/Tests/AK/TestUtf8.cpp
+++ b/Tests/AK/TestUtf8.cpp
@@ -34,7 +34,7 @@ TEST_CASE(decode_utf8)
     EXPECT(valid_bytes == (size_t)utf8.byte_length());
 
     u32 expected[] = { 1055, 1088, 1080, 1074, 1077, 1090, 44, 32, 1084, 1080, 1088, 33, 32, 128512, 32, 947, 949, 953, 940, 32, 963, 959, 965, 32, 954, 972, 963, 956, 959, 962, 32, 12371, 12435, 12395, 12385, 12399, 19990, 30028 };
-    DeprecatedString expected_underlying_bytes[] = { "П", "р", "и", "в", "е", "т", ",", " ", "м", "и", "р", "!", " ", "😀", " ", "γ", "ε", "ι", "ά", " ", "σ", "ο", "υ", " ", "κ", "ό", "σ", "μ", "ο", "ς", " ", "こ", "ん", "に", "ち", "は", "世", "界" };
+    ByteString expected_underlying_bytes[] = { "П", "р", "и", "в", "е", "т", ",", " ", "м", "и", "р", "!", " ", "😀", " ", "γ", "ε", "ι", "ά", " ", "σ", "ο", "υ", " ", "κ", "ό", "σ", "μ", "ο", "ς", " ", "こ", "ん", "に", "ち", "は", "世", "界" };
     size_t expected_size = sizeof(expected) / sizeof(expected[0]);
 
     size_t i = 0;
@@ -166,7 +166,7 @@ TEST_CASE(decode_invalid_ut8)
         char raw_data[] = { 'a', 'b', (char)0xA0, 'd' };
         Utf8View view { StringView { raw_data, 4 } };
         u32 expected_characters[] = { 'a', 'b', 0xFFFD, 'd' };
-        DeprecatedString expected_underlying_bytes[] = { "a", "b", "\xA0", "d" };
+        ByteString expected_underlying_bytes[] = { "a", "b", "\xA0", "d" };
         size_t expected_size = sizeof(expected_characters) / sizeof(expected_characters[0]);
         size_t i = 0;
         for (auto it = view.begin(); it != view.end(); ++it) {
@@ -184,7 +184,7 @@ TEST_CASE(decode_invalid_ut8)
         char raw_data[] = { 'a', 'b', (char)0xC0, 'd', 'e' };
         Utf8View view { StringView { raw_data, 5 } };
         u32 expected_characters[] = { 'a', 'b', 0xFFFD, 'd', 'e' };
-        DeprecatedString expected_underlying_bytes[] = { "a", "b", "\xC0", "d", "e" };
+        ByteString expected_underlying_bytes[] = { "a", "b", "\xC0", "d", "e" };
         size_t expected_size = sizeof(expected_characters) / sizeof(expected_characters[0]);
         size_t i = 0;
         for (auto it = view.begin(); it != view.end(); ++it) {
@@ -202,7 +202,7 @@ TEST_CASE(decode_invalid_ut8)
         char raw_data[] = { 'a', 'b', (char)0x90, 'd' };
         Utf8View view { StringView { raw_data, 4 } };
         u32 expected_characters[] = { 'a', 'b', 0xFFFD, 'd' };
-        DeprecatedString expected_underlying_bytes[] = { "a", "b", "\x90", "d" };
+        ByteString expected_underlying_bytes[] = { "a", "b", "\x90", "d" };
         size_t expected_size = sizeof(expected_characters) / sizeof(expected_characters[0]);
         size_t i = 0;
         for (auto it = view.begin(); it != view.end(); ++it) {
@@ -220,7 +220,7 @@ TEST_CASE(decode_invalid_ut8)
         char raw_data[] = { 'a', 'b', 'c', (char)0x90 };
         Utf8View view { StringView { raw_data, 4 } };
         u32 expected_characters[] = { 'a', 'b', 'c', 0xFFFD };
-        DeprecatedString expected_underlying_bytes[] = { "a", "b", "c", "\x90" };
+        ByteString expected_underlying_bytes[] = { "a", "b", "c", "\x90" };
         size_t expected_size = sizeof(expected_characters) / sizeof(expected_characters[0]);
         size_t i = 0;
         for (auto it = view.begin(); it != view.end(); ++it) {
@@ -247,7 +247,7 @@ TEST_CASE(decode_invalid_ut8)
         // https://www.unicode.org/versions/Unicode14.0.0/ch03.pdf , section "U+FFFD Substitution of Maximal Subparts"
         // However, that would go against how we deal with several other kinds of errors, so we stick to emitting only one U+FFFD.
         u32 expected_characters[] = { 'a', 0xFFFD, 'b' };
-        DeprecatedString expected_underlying_bytes[] = { "a", "\xF4\xA3\x91\x96", "b" };
+        ByteString expected_underlying_bytes[] = { "a", "\xF4\xA3\x91\x96", "b" };
         size_t expected_size = sizeof(expected_characters) / sizeof(expected_characters[0]);
         size_t i = 0;
         for (auto it = view.begin(); it != view.end(); ++it) {
diff --git a/Tests/AK/TestVariant.cpp b/Tests/AK/TestVariant.cpp
index 1e075758f69..d965a85c7d3 100644
--- a/Tests/AK/TestVariant.cpp
+++ b/Tests/AK/TestVariant.cpp
@@ -18,21 +18,21 @@ struct Object : public RefCounted<Object> {
 
 TEST_CASE(basic)
 {
-    Variant<int, DeprecatedString> the_value { 42 };
+    Variant<int, ByteString> the_value { 42 };
     EXPECT(the_value.has<int>());
     EXPECT_EQ(the_value.get<int>(), 42);
-    the_value = DeprecatedString("42");
-    EXPECT(the_value.has<DeprecatedString>());
-    EXPECT_EQ(the_value.get<DeprecatedString>(), "42");
+    the_value = ByteString("42");
+    EXPECT(the_value.has<ByteString>());
+    EXPECT_EQ(the_value.get<ByteString>(), "42");
 }
 
 TEST_CASE(visit)
 {
     bool correct = false;
-    Variant<int, DeprecatedString, float> the_value { 42.0f };
+    Variant<int, ByteString, float> the_value { 42.0f };
     the_value.visit(
         [&](int const&) { correct = false; },
-        [&](DeprecatedString const&) { correct = false; },
+        [&](ByteString const&) { correct = false; },
         [&](float const&) { correct = true; });
     EXPECT(correct);
 }
@@ -40,10 +40,10 @@ TEST_CASE(visit)
 TEST_CASE(visit_const)
 {
     bool correct = false;
-    Variant<int, DeprecatedString> const the_value { "42"sv };
+    Variant<int, ByteString> const the_value { "42"sv };
 
     the_value.visit(
-        [&](DeprecatedString const&) { correct = true; },
+        [&](ByteString const&) { correct = true; },
         [&](auto&) {},
         [&](auto const&) {});
 
@@ -52,7 +52,7 @@ TEST_CASE(visit_const)
     correct = false;
     auto the_value_but_not_const = the_value;
     the_value_but_not_const.visit(
-        [&](DeprecatedString const&) { correct = true; },
+        [&](ByteString const&) { correct = true; },
         [&](auto&) {});
 
     EXPECT(correct);
@@ -168,13 +168,13 @@ TEST_CASE(duplicated_types)
 
 TEST_CASE(return_values)
 {
-    using MyVariant = Variant<int, DeprecatedString, float>;
+    using MyVariant = Variant<int, ByteString, float>;
     {
         MyVariant the_value { 42.0f };
 
         float value = the_value.visit(
             [&](int const&) { return 1.0f; },
-            [&](DeprecatedString const&) { return 2.0f; },
+            [&](ByteString const&) { return 2.0f; },
             [&](float const& f) { return f; });
         EXPECT_EQ(value, 42.0f);
     }
@@ -183,17 +183,17 @@ TEST_CASE(return_values)
 
         int value = the_value.visit(
             [&](int& i) { return i; },
-            [&](DeprecatedString&) { return 2; },
+            [&](ByteString&) { return 2; },
             [&](float&) { return 3; });
         EXPECT_EQ(value, 42);
     }
     {
         const MyVariant the_value { "str" };
 
-        DeprecatedString value = the_value.visit(
-            [&](int const&) { return DeprecatedString { "wrong" }; },
-            [&](DeprecatedString const& s) { return s; },
-            [&](float const&) { return DeprecatedString { "wrong" }; });
+        ByteString value = the_value.visit(
+            [&](int const&) { return ByteString { "wrong" }; },
+            [&](ByteString const& s) { return s; },
+            [&](float const&) { return ByteString { "wrong" }; });
         EXPECT_EQ(value, "str");
     }
 }
@@ -201,11 +201,11 @@ TEST_CASE(return_values)
 TEST_CASE(return_values_by_reference)
 {
     auto ref = adopt_ref_if_nonnull(new (nothrow) Object());
-    Variant<int, DeprecatedString, float> the_value { 42.0f };
+    Variant<int, ByteString, float> the_value { 42.0f };
 
     auto& value = the_value.visit(
         [&](int const&) -> RefPtr<Object>& { return ref; },
-        [&](DeprecatedString const&) -> RefPtr<Object>& { return ref; },
+        [&](ByteString const&) -> RefPtr<Object>& { return ref; },
         [&](float const&) -> RefPtr<Object>& { return ref; });
 
     EXPECT_EQ(ref, value);
@@ -223,7 +223,7 @@ struct HoldsFloat {
 TEST_CASE(copy_assign)
 {
     {
-        Variant<int, DeprecatedString, float> the_value { 42.0f };
+        Variant<int, ByteString, float> the_value { 42.0f };
 
         VERIFY(the_value.has<float>());
         EXPECT_EQ(the_value.get<float>(), 42.0f);
@@ -233,12 +233,12 @@ TEST_CASE(copy_assign)
         VERIFY(the_value.has<int>());
         EXPECT_EQ(the_value.get<int>(), 12);
 
-        the_value = DeprecatedString("Hello, world!");
-        VERIFY(the_value.has<DeprecatedString>());
-        EXPECT_EQ(the_value.get<DeprecatedString>(), "Hello, world!");
+        the_value = ByteString("Hello, world!");
+        VERIFY(the_value.has<ByteString>());
+        EXPECT_EQ(the_value.get<ByteString>(), "Hello, world!");
     }
     {
-        Variant<HoldsInt, DeprecatedString, HoldsFloat> the_value { HoldsFloat { 42.0f } };
+        Variant<HoldsInt, ByteString, HoldsFloat> the_value { HoldsFloat { 42.0f } };
 
         VERIFY(the_value.has<HoldsFloat>());
         EXPECT_EQ(the_value.get<HoldsFloat>().f, 42.0f);
@@ -248,9 +248,9 @@ TEST_CASE(copy_assign)
         VERIFY(the_value.has<HoldsInt>());
         EXPECT_EQ(the_value.get<HoldsInt>().i, 12);
 
-        the_value = DeprecatedString("Hello, world!");
-        VERIFY(the_value.has<DeprecatedString>());
-        EXPECT_EQ(the_value.get<DeprecatedString>(), "Hello, world!");
+        the_value = ByteString("Hello, world!");
+        VERIFY(the_value.has<ByteString>());
+        EXPECT_EQ(the_value.get<ByteString>(), "Hello, world!");
     }
 }
 
diff --git a/Tests/AK/TestVector.cpp b/Tests/AK/TestVector.cpp
index edbd451dd78..4250f29356d 100644
--- a/Tests/AK/TestVector.cpp
+++ b/Tests/AK/TestVector.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/OwnPtr.h>
 #include <AK/ReverseIterator.h>
 #include <AK/String.h>
@@ -38,18 +38,18 @@ TEST_CASE(ints)
 
 TEST_CASE(strings)
 {
-    Vector<DeprecatedString> strings;
+    Vector<ByteString> strings;
     strings.append("ABC");
     strings.append("DEF");
 
     int loop_counter = 0;
-    for (DeprecatedString const& string : strings) {
+    for (ByteString const& string : strings) {
         EXPECT(!string.is_empty());
         ++loop_counter;
     }
 
     loop_counter = 0;
-    for (auto& string : (const_cast<Vector<DeprecatedString> const&>(strings))) {
+    for (auto& string : (const_cast<Vector<ByteString> const&>(strings))) {
         EXPECT(!string.is_empty());
         ++loop_counter;
     }
@@ -58,7 +58,7 @@ TEST_CASE(strings)
 
 TEST_CASE(strings_insert_ordered)
 {
-    Vector<DeprecatedString> strings;
+    Vector<ByteString> strings;
     strings.append("abc");
     strings.append("def");
     strings.append("ghi");
@@ -161,12 +161,12 @@ TEST_CASE(vector_compare)
     EXPECT_EQ(ints.size(), 1000u);
     EXPECT_EQ(ints, same_ints);
 
-    Vector<DeprecatedString> strings;
-    Vector<DeprecatedString> same_strings;
+    Vector<ByteString> strings;
+    Vector<ByteString> same_strings;
 
     for (int i = 0; i < 1000; ++i) {
-        strings.append(DeprecatedString::number(i));
-        same_strings.append(DeprecatedString::number(i));
+        strings.append(ByteString::number(i));
+        same_strings.append(ByteString::number(i));
     }
 
     EXPECT_EQ(strings.size(), 1000u);
@@ -176,9 +176,9 @@ TEST_CASE(vector_compare)
 TEST_CASE(grow_past_inline_capacity)
 {
     auto make_vector = [] {
-        Vector<DeprecatedString, 16> strings;
+        Vector<ByteString, 16> strings;
         for (int i = 0; i < 32; ++i) {
-            strings.append(DeprecatedString::number(i));
+            strings.append(ByteString::number(i));
         }
         return strings;
     };
@@ -284,7 +284,7 @@ TEST_CASE(remove_all_matching)
 TEST_CASE(nonnullownptrvector)
 {
     struct Object {
-        DeprecatedString string;
+        ByteString string;
     };
     Vector<NonnullOwnPtr<Object>> objects;
 
diff --git a/Tests/AK/TestWeakPtr.cpp b/Tests/AK/TestWeakPtr.cpp
index b673294585b..3c44aae5f2f 100644
--- a/Tests/AK/TestWeakPtr.cpp
+++ b/Tests/AK/TestWeakPtr.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/WeakPtr.h>
 #include <AK/Weakable.h>
 
diff --git a/Tests/JSSpecCompiler/test-runner.cpp b/Tests/JSSpecCompiler/test-runner.cpp
index f926ea40806..eaedb29d4c1 100644
--- a/Tests/JSSpecCompiler/test-runner.cpp
+++ b/Tests/JSSpecCompiler/test-runner.cpp
@@ -49,9 +49,9 @@ static const LexicalPath path_to_compiler_binary = [] {
 }();
 static const LexicalPath path_to_tests_directory { relative_path_to_test };
 
-Vector<DeprecatedString> build_command_line_arguments(LexicalPath const& test_source, TestDescription const& description)
+Vector<ByteString> build_command_line_arguments(LexicalPath const& test_source, TestDescription const& description)
 {
-    Vector<DeprecatedString> result;
+    Vector<ByteString> result;
 
     StringBuilder dump_ast_option;
     StringBuilder dump_cfg_option;
@@ -69,9 +69,9 @@ Vector<DeprecatedString> build_command_line_arguments(LexicalPath const& test_so
         }
     }
     if (!dump_ast_option.is_empty())
-        result.append(DeprecatedString::formatted("--dump-ast={}", dump_ast_option.string_view()));
+        result.append(ByteString::formatted("--dump-ast={}", dump_ast_option.string_view()));
     if (!dump_cfg_option.is_empty())
-        result.append(DeprecatedString::formatted("--dump-cfg={}", dump_cfg_option.string_view()));
+        result.append(ByteString::formatted("--dump-cfg={}", dump_cfg_option.string_view()));
 
     if (test_source.has_extension(".cpp"sv))
         result.append("-xc++"sv);
@@ -149,7 +149,7 @@ TEST_CASE(test_regression)
             dbgln("Running {}...", source);
 
             auto path_to_test = LexicalPath::join(path_to_tests_directory.string(), source);
-            auto path_to_expectation = LexicalPath::join(path_to_tests_directory.string(), DeprecatedString::formatted("{}.expectation", source));
+            auto path_to_expectation = LexicalPath::join(path_to_tests_directory.string(), ByteString::formatted("{}.expectation", source));
 
             auto process = MUST(Core::Process::spawn({
                 .path = path_to_compiler_binary.string(),
diff --git a/Tests/Kernel/TestKernelFilePermissions.cpp b/Tests/Kernel/TestKernelFilePermissions.cpp
index 12b7831d0a1..70da9deb497 100644
--- a/Tests/Kernel/TestKernelFilePermissions.cpp
+++ b/Tests/Kernel/TestKernelFilePermissions.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibFileSystem/FileSystem.h>
 #include <LibTest/TestCase.h>
 #include <fcntl.h>
@@ -81,11 +81,11 @@ TEST_CASE(test_change_file_location)
     ftruncate(fd, 0);
     EXPECT(fchmod(fd, 06755) != -1);
 
-    auto suid_path_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+    auto suid_path_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
 
-    auto suid_path = suid_path_string.to_deprecated_string();
+    auto suid_path = suid_path_string.to_byte_string();
     EXPECT(suid_path.characters());
-    auto new_path = DeprecatedString::formatted("{}.renamed", suid_path);
+    auto new_path = ByteString::formatted("{}.renamed", suid_path);
 
     rename(suid_path.characters(), new_path.characters());
 
diff --git a/Tests/Kernel/TestKernelPledge.cpp b/Tests/Kernel/TestKernelPledge.cpp
index 89ff01e5a0b..6cc45ae7090 100644
--- a/Tests/Kernel/TestKernelPledge.cpp
+++ b/Tests/Kernel/TestKernelPledge.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibTest/TestCase.h>
 #include <errno.h>
 #include <unistd.h>
@@ -18,7 +18,7 @@ TEST_CASE(test_nonexistent_pledge)
 
 TEST_CASE(test_pledge_argument_validation)
 {
-    auto const long_argument = DeprecatedString::repeated('a', 2048);
+    auto const long_argument = ByteString::repeated('a', 2048);
 
     auto res = pledge(long_argument.characters(), "stdio");
     EXPECT_EQ(res, -1);
diff --git a/Tests/Kernel/crash.cpp b/Tests/Kernel/crash.cpp
index 608926b1946..0c128f437ab 100644
--- a/Tests/Kernel/crash.cpp
+++ b/Tests/Kernel/crash.cpp
@@ -6,7 +6,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #if ARCH(X86_64)
 #    include <Kernel/Arch/x86_64/IO.h>
diff --git a/Tests/Kernel/fuzz-syscalls.cpp b/Tests/Kernel/fuzz-syscalls.cpp
index aab8ab49377..aefa2ef6b3a 100644
--- a/Tests/Kernel/fuzz-syscalls.cpp
+++ b/Tests/Kernel/fuzz-syscalls.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/Random.h>
 #include <AK/StringBuilder.h>
@@ -101,7 +101,7 @@ static void do_weird_call(size_t attempt, int syscall_fn, size_t arg1, size_t ar
         builder.appendff("{:p}", fake_params[i]);
     }
     builder.append(']');
-    dbgln("{}", builder.to_deprecated_string());
+    dbgln("{}", builder.to_byte_string());
 
     // Actually do the syscall ('fake_params' is passed indirectly, if any of arg1, arg2, or arg3 point to it.
     int rc = syscall(Syscall::Function(syscall_fn), arg1, arg2, arg3);
diff --git a/Tests/Kernel/stress-truncate.cpp b/Tests/Kernel/stress-truncate.cpp
index 1e066155c5a..72803ca8f1e 100644
--- a/Tests/Kernel/stress-truncate.cpp
+++ b/Tests/Kernel/stress-truncate.cpp
@@ -18,7 +18,7 @@ int main(int argc, char** argv)
     for (auto i = 0; i < argc; ++i)
         arguments.append({ argv[i], strlen(argv[i]) });
 
-    DeprecatedString target;
+    ByteString target;
     int max_file_size = 1024 * 1024;
     int count = 1024;
 
diff --git a/Tests/Kernel/stress-writeread.cpp b/Tests/Kernel/stress-writeread.cpp
index 352cdb16af6..f8cfdb8010c 100644
--- a/Tests/Kernel/stress-writeread.cpp
+++ b/Tests/Kernel/stress-writeread.cpp
@@ -65,7 +65,7 @@ int main(int argc, char** argv)
     for (auto i = 0; i < argc; ++i)
         arguments.append({ argv[i], strlen(argv[i]) });
 
-    DeprecatedString target;
+    ByteString target;
     int min_block_offset = 0;
     int block_length = 2048;
     int block_size = 512;
diff --git a/Tests/LibAudio/TestFLACSpec.cpp b/Tests/LibAudio/TestFLACSpec.cpp
index 34c8dd06cff..6192064c1e6 100644
--- a/Tests/LibAudio/TestFLACSpec.cpp
+++ b/Tests/LibAudio/TestFLACSpec.cpp
@@ -17,21 +17,21 @@ struct DiscoverFLACTestsHack {
             auto path = LexicalPath::join(directory.path().string(), entry.name);
             if (path.extension() == "flac"sv) {
                 Test::add_test_case_to_suite(adopt_ref(*new ::Test::TestCase(
-                    DeprecatedString::formatted("flac_spec_test_{}", path.basename()),
+                    ByteString::formatted("flac_spec_test_{}", path.basename()),
                     [path = move(path)]() {
                         auto file = Core::File::open(path.string(), Core::File::OpenMode::Read);
                         if (file.is_error()) {
-                            FAIL(DeprecatedString::formatted("{}", file.error()));
+                            FAIL(ByteString::formatted("{}", file.error()));
                             return;
                         }
                         auto buffered_file = Core::InputBufferedFile::create(file.release_value());
                         if (buffered_file.is_error()) {
-                            FAIL(DeprecatedString::formatted("{}", buffered_file.error()));
+                            FAIL(ByteString::formatted("{}", buffered_file.error()));
                             return;
                         }
                         auto result = Audio::FlacLoaderPlugin::create(buffered_file.release_value());
                         if (result.is_error()) {
-                            FAIL(DeprecatedString::formatted("{}", result.error()));
+                            FAIL(ByteString::formatted("{}", result.error()));
                             return;
                         }
 
@@ -40,7 +40,7 @@ struct DiscoverFLACTestsHack {
                         while (true) {
                             auto maybe_samples = loader->load_chunks(2 * MiB);
                             if (maybe_samples.is_error()) {
-                                FAIL(DeprecatedString::formatted("{}", maybe_samples.error()));
+                                FAIL(ByteString::formatted("{}", maybe_samples.error()));
                                 return;
                             }
                             maybe_samples.value().remove_all_matching([](auto& chunk) { return chunk.is_empty(); });
diff --git a/Tests/LibC/TestLibCInodeWatcher.cpp b/Tests/LibC/TestLibCInodeWatcher.cpp
index 285bc23df38..fb2e8de5e9a 100644
--- a/Tests/LibC/TestLibCInodeWatcher.cpp
+++ b/Tests/LibC/TestLibCInodeWatcher.cpp
@@ -23,12 +23,12 @@ static int read_event(int fd)
     return rc;
 }
 
-static DeprecatedString get_event_name()
+static ByteString get_event_name()
 {
     if (event->name_length == 0)
-        return DeprecatedString();
+        return ByteString();
 
-    return DeprecatedString { event->name, event->name_length - 1 };
+    return ByteString { event->name, event->name_length - 1 };
 }
 
 TEST_CASE(inode_watcher_metadata_modified_event)
diff --git a/Tests/LibC/TestLibCMkTemp.cpp b/Tests/LibC/TestLibCMkTemp.cpp
index 658f55ad04b..ccbd2cf38cf 100644
--- a/Tests/LibC/TestLibCMkTemp.cpp
+++ b/Tests/LibC/TestLibCMkTemp.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibFileSystem/FileSystem.h>
 #include <LibTest/TestCase.h>
 #include <fcntl.h>
@@ -23,7 +23,7 @@ TEST_CASE(test_mktemp_unique_filename)
 
     if (fork() == 0) {
         char path[] = "/tmp/test.mktemp.XXXXXX";
-        auto temp_path = DeprecatedString::formatted("{}", mktemp(path));
+        auto temp_path = ByteString::formatted("{}", mktemp(path));
         EXPECT(temp_path.characters());
         unlink(path);
 
@@ -33,10 +33,10 @@ TEST_CASE(test_mktemp_unique_filename)
     } else {
         wait(NULL);
 
-        auto path1 = DeprecatedString::formatted("{}", reinterpret_cast<char const*>(ptr));
+        auto path1 = ByteString::formatted("{}", reinterpret_cast<char const*>(ptr));
 
         char path[] = "/tmp/test.mktemp.XXXXXX";
-        auto path2 = DeprecatedString::formatted("{}", mktemp(path));
+        auto path2 = ByteString::formatted("{}", mktemp(path));
         EXPECT(path2.characters());
         unlink(path);
 
@@ -53,7 +53,7 @@ TEST_CASE(test_mkdtemp_unique_filename)
 
     if (fork() == 0) {
         char path[] = "/tmp/test.mkdtemp.XXXXXX";
-        auto temp_path = DeprecatedString::formatted("{}", mkdtemp(path));
+        auto temp_path = ByteString::formatted("{}", mkdtemp(path));
         EXPECT(temp_path.characters());
         rmdir(path);
 
@@ -63,10 +63,10 @@ TEST_CASE(test_mkdtemp_unique_filename)
     } else {
         wait(NULL);
 
-        auto path1 = DeprecatedString::formatted("{}", reinterpret_cast<char const*>(ptr));
+        auto path1 = ByteString::formatted("{}", reinterpret_cast<char const*>(ptr));
 
         char path[] = "/tmp/test.mkdtemp.XXXXXX";
-        auto path2 = DeprecatedString::formatted("{}", mkdtemp(path));
+        auto path2 = ByteString::formatted("{}", mkdtemp(path));
         EXPECT(path2.characters());
         rmdir(path);
 
@@ -86,8 +86,8 @@ TEST_CASE(test_mkstemp_unique_filename)
         auto fd = mkstemp(path);
         EXPECT_NE(fd, -1);
 
-        auto temp_path_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
-        auto temp_path = temp_path_string.to_deprecated_string();
+        auto temp_path_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+        auto temp_path = temp_path_string.to_byte_string();
         EXPECT(temp_path.characters());
 
         close(fd);
@@ -99,14 +99,14 @@ TEST_CASE(test_mkstemp_unique_filename)
     } else {
         wait(NULL);
 
-        auto path1 = DeprecatedString::formatted("{}", reinterpret_cast<char const*>(ptr));
+        auto path1 = ByteString::formatted("{}", reinterpret_cast<char const*>(ptr));
 
         char path[] = "/tmp/test.mkstemp.XXXXXX";
         auto fd = mkstemp(path);
         EXPECT(fd != -1);
 
-        auto path2_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
-        auto path2 = path2_string.to_deprecated_string();
+        auto path2_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+        auto path2 = path2_string.to_byte_string();
         EXPECT(path2.characters());
 
         close(fd);
@@ -128,8 +128,8 @@ TEST_CASE(test_mkstemps_unique_filename)
         auto fd = mkstemps(path, 6);
         EXPECT_NE(fd, -1);
 
-        auto temp_path_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
-        auto temp_path = temp_path_string.to_deprecated_string();
+        auto temp_path_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+        auto temp_path = temp_path_string.to_byte_string();
         EXPECT(temp_path.characters());
 
         close(fd);
@@ -145,14 +145,14 @@ TEST_CASE(test_mkstemps_unique_filename)
     } else {
         wait(NULL);
 
-        auto path1 = DeprecatedString::formatted("{}", reinterpret_cast<char const*>(ptr));
+        auto path1 = ByteString::formatted("{}", reinterpret_cast<char const*>(ptr));
 
         char path[] = "/tmp/test.mkstemps.prefixXXXXXXsuffix";
         auto fd = mkstemps(path, 6);
         EXPECT(fd != -1);
 
-        auto path2_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
-        auto path2 = path2_string.to_deprecated_string();
+        auto path2_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+        auto path2 = path2_string.to_byte_string();
         EXPECT(path2.characters());
 
         close(fd);
diff --git a/Tests/LibC/TestMemmem.cpp b/Tests/LibC/TestMemmem.cpp
index 5e814b16d54..3ba65dfe949 100644
--- a/Tests/LibC/TestMemmem.cpp
+++ b/Tests/LibC/TestMemmem.cpp
@@ -37,7 +37,7 @@ TEST_CASE(memmem_search)
         auto expected = test_case.matching_offset >= 0 ? test_case.haystack + test_case.matching_offset : nullptr;
         auto result = memmem(test_case.haystack, test_case.haystack_length, test_case.needle, test_case.needle_length);
         if (result != expected) {
-            FAIL(DeprecatedString::formatted("Test {} FAILED! expected {:p}, got {:p}", i, expected, result));
+            FAIL(ByteString::formatted("Test {} FAILED! expected {:p}, got {:p}", i, expected, result));
         }
         ++i;
     }
diff --git a/Tests/LibC/TestMkDir.cpp b/Tests/LibC/TestMkDir.cpp
index 37da5d1f99d..d8bb27879c5 100644
--- a/Tests/LibC/TestMkDir.cpp
+++ b/Tests/LibC/TestMkDir.cpp
@@ -12,9 +12,9 @@
 #include <time.h>
 #include <unistd.h>
 
-static DeprecatedString random_dirname()
+static ByteString random_dirname()
 {
-    return DeprecatedString::formatted("/tmp/test_mkdir_{:04x}", (u16)rand());
+    return ByteString::formatted("/tmp/test_mkdir_{:04x}", (u16)rand());
 }
 
 TEST_SETUP
@@ -46,7 +46,7 @@ TEST_CASE(insufficient_permissions)
 TEST_CASE(nonexistent_parent)
 {
     auto parent = random_dirname();
-    auto child = DeprecatedString::formatted("{}/foo", parent);
+    auto child = ByteString::formatted("{}/foo", parent);
     int res = mkdir(child.characters(), 0755);
     int cached_errno = errno;
     EXPECT(res < 0);
diff --git a/Tests/LibC/TestPwd.cpp b/Tests/LibC/TestPwd.cpp
index ed7e35b2046..7a65d7bb0ae 100644
--- a/Tests/LibC/TestPwd.cpp
+++ b/Tests/LibC/TestPwd.cpp
@@ -10,7 +10,7 @@
 #include <pwd.h>
 
 struct PasswdEntry {
-    DeprecatedString name;
+    ByteString name;
     uid_t uid {};
 };
 
diff --git a/Tests/LibC/TestQsort.cpp b/Tests/LibC/TestQsort.cpp
index dbc0b46b651..587451ec878 100644
--- a/Tests/LibC/TestQsort.cpp
+++ b/Tests/LibC/TestQsort.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/QuickSort.h>
 #include <AK/Random.h>
 #include <AK/Vector.h>
@@ -54,7 +54,7 @@ TEST_CASE(quick_sort)
             auto const& key1 = test_objects[i].m_key;
             auto const& key2 = test_objects[i + 1].m_key;
             if (key1 > key2) {
-                FAIL(DeprecatedString::formatted("saw key {} before key {}\n", key1, key2));
+                FAIL(ByteString::formatted("saw key {} before key {}\n", key1, key2));
             }
         }
         // Check that the object's payloads have not been corrupted
@@ -62,7 +62,7 @@ TEST_CASE(quick_sort)
             auto const expected = calc_payload_for_pos(i);
             auto const payload = test_objects[i].m_payload;
             if (payload != expected) {
-                FAIL(DeprecatedString::formatted("Expected payload {} for pos {}, got payload {}", expected, i, payload));
+                FAIL(ByteString::formatted("Expected payload {} for pos {}, got payload {}", expected, i, payload));
             }
         }
     }
diff --git a/Tests/LibC/TestRealpath.cpp b/Tests/LibC/TestRealpath.cpp
index 613858fc9cf..2d6256a7d10 100644
--- a/Tests/LibC/TestRealpath.cpp
+++ b/Tests/LibC/TestRealpath.cpp
@@ -6,7 +6,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <errno.h>
 #include <limits.h>
@@ -24,7 +24,7 @@ static constexpr size_t ITERATION_DEPTH = 17;
 static void check_result(char const* what, StringView expected, char const* actual)
 {
     if (expected != actual)
-        FAIL(DeprecatedString::formatted("Expected {} to be \"{}\" ({} characters)", what, actual, actual ? strlen(actual) : 0));
+        FAIL(ByteString::formatted("Expected {} to be \"{}\" ({} characters)", what, actual, actual ? strlen(actual) : 0));
 }
 
 TEST_CASE(overlong_realpath)
@@ -50,7 +50,7 @@ TEST_CASE(overlong_realpath)
     expected.append({ tmp_dir, strlen(tmp_dir) });
 
     // But first, demonstrate the functionality at a reasonable depth:
-    auto expected_str = expected.to_deprecated_string();
+    auto expected_str = expected.to_byte_string();
     check_result("getwd", expected_str, getwd(static_cast<char*>(calloc(1, PATH_MAX))));
     check_result("getcwd", expected_str, getcwd(nullptr, 0));
     check_result("realpath", expected_str, realpath(".", nullptr));
@@ -59,7 +59,7 @@ TEST_CASE(overlong_realpath)
         ret = mkdir(PATH_LOREM_250, S_IRWXU);
         if (ret < 0) {
             perror("mkdir iter");
-            FAIL(DeprecatedString::formatted("Unable to mkdir the overlong path fragment in iteration {}", i));
+            FAIL(ByteString::formatted("Unable to mkdir the overlong path fragment in iteration {}", i));
             return;
         }
         expected.append('/');
@@ -67,14 +67,14 @@ TEST_CASE(overlong_realpath)
         ret = chdir(PATH_LOREM_250);
         if (ret < 0) {
             perror("chdir iter");
-            FAIL(DeprecatedString::formatted("Unable to chdir to the overlong path fragment in iteration {}", i));
+            FAIL(ByteString::formatted("Unable to chdir to the overlong path fragment in iteration {}", i));
             return;
         }
     }
     outln("cwd should now be ridiculously large");
 
     // Evaluate
-    expected_str = expected.to_deprecated_string();
+    expected_str = expected.to_byte_string();
 
     check_result("getwd", {}, getwd(static_cast<char*>(calloc(1, PATH_MAX))));
     check_result("getcwd", expected_str, getcwd(nullptr, 0));
diff --git a/Tests/LibC/TestSearch.cpp b/Tests/LibC/TestSearch.cpp
index b1df6533c3b..2b7a0d30ad8 100644
--- a/Tests/LibC/TestSearch.cpp
+++ b/Tests/LibC/TestSearch.cpp
@@ -165,7 +165,7 @@ void twalk_action(void const* node, VISIT order, int depth)
     // Special case: End signaled by tester.
     if (depth == TWALK_CHECK_END) {
         if (tests[count].depth != TWALK_END_MARKER) {
-            FAIL(DeprecatedString::formatted("Expected action (node={:#x}, order={}, depth={}), but twalk ended early.",
+            FAIL(ByteString::formatted("Expected action (node={:#x}, order={}, depth={}), but twalk ended early.",
                 tests[count].node, U8(tests[count].order), tests[count].depth));
         }
         return;
@@ -173,7 +173,7 @@ void twalk_action(void const* node, VISIT order, int depth)
 
     // Special case: End marker reached.
     if (tests[count].depth == TWALK_END_MARKER) {
-        FAIL(DeprecatedString::formatted("Expected end, but twalk sent another action (node={:#x}, order={}, depth={}).",
+        FAIL(ByteString::formatted("Expected end, but twalk sent another action (node={:#x}, order={}, depth={}).",
             node, U8(order), depth));
         return;
     }
diff --git a/Tests/LibC/TestSnprintf.cpp b/Tests/LibC/TestSnprintf.cpp
index 17c3b62acbd..91a8ac2c780 100644
--- a/Tests/LibC/TestSnprintf.cpp
+++ b/Tests/LibC/TestSnprintf.cpp
@@ -28,7 +28,7 @@ struct Testcase {
     size_t dest_expected_n; // == dest_n
 };
 
-static DeprecatedString show(ByteBuffer const& buf)
+static ByteString show(ByteBuffer const& buf)
 {
     StringBuilder builder;
     for (size_t i = 0; i < buf.size(); ++i) {
@@ -43,7 +43,7 @@ static DeprecatedString show(ByteBuffer const& buf)
             builder.append('_');
     }
     builder.append(')');
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 template<typename TArg>
diff --git a/Tests/LibC/TestStrlcpy.cpp b/Tests/LibC/TestStrlcpy.cpp
index 98317e13a3a..dbc697f1a77 100644
--- a/Tests/LibC/TestStrlcpy.cpp
+++ b/Tests/LibC/TestStrlcpy.cpp
@@ -22,7 +22,7 @@ struct Testcase {
     size_t dest_expected_n; // == dest_n
 };
 
-static DeprecatedString show(ByteBuffer const& buf)
+static ByteString show(ByteBuffer const& buf)
 {
     StringBuilder builder;
     for (size_t i = 0; i < buf.size(); ++i) {
@@ -37,7 +37,7 @@ static DeprecatedString show(ByteBuffer const& buf)
             builder.append('_');
     }
     builder.append(')');
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 static bool test_single(Testcase const& testcase)
diff --git a/Tests/LibC/TestStrtodAccuracy.cpp b/Tests/LibC/TestStrtodAccuracy.cpp
index 15005ae40c6..9b7c5012fd8 100644
--- a/Tests/LibC/TestStrtodAccuracy.cpp
+++ b/Tests/LibC/TestStrtodAccuracy.cpp
@@ -7,7 +7,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <stdlib.h>
 #include <string.h>
@@ -330,7 +330,7 @@ static long long hex_to_ll(char const* hex)
         } else if ('a' <= ch && ch <= 'f') {
             digit = ch - 'a' + 10;
         } else {
-            FAIL(DeprecatedString::formatted("\n!!! Encountered char {:02x} at {}", ch, i));
+            FAIL(ByteString::formatted("\n!!! Encountered char {:02x} at {}", ch, i));
             return result;
         }
         result <<= 4;
@@ -366,7 +366,7 @@ TEST_CASE(strtod_accuracy)
     }
     outln("Out of {} tests, saw {} successes and {} fails.", NUM_TESTCASES, successes, fails);
     if (fails != 0) {
-        FAIL(DeprecatedString::formatted("{} strtod tests failed", fails));
+        FAIL(ByteString::formatted("{} strtod tests failed", fails));
     }
 
     outln("PASS (with leniency up to {} ULP from the exact solution)", LENIENCY);
diff --git a/Tests/LibC/TestWchar.cpp b/Tests/LibC/TestWchar.cpp
index 804d837f276..37876c0c63e 100644
--- a/Tests/LibC/TestWchar.cpp
+++ b/Tests/LibC/TestWchar.cpp
@@ -215,7 +215,7 @@ TEST_CASE(mbsinit)
     size_t ret = mbrtowc(nullptr, "\xdf", 1, &state);
 
     if (ret != -2ul)
-        FAIL(DeprecatedString::formatted("mbrtowc accepted partial multibyte sequence with return code {} (expected -2)", static_cast<ssize_t>(ret)));
+        FAIL(ByteString::formatted("mbrtowc accepted partial multibyte sequence with return code {} (expected -2)", static_cast<ssize_t>(ret)));
 
     // Ensure that we are not in an initial state.
     EXPECT(mbsinit(&state) == 0);
@@ -224,7 +224,7 @@ TEST_CASE(mbsinit)
     ret = mbrtowc(nullptr, "\xbf", 1, &state);
 
     if (ret != 1ul)
-        FAIL(DeprecatedString::formatted("mbrtowc did not consume the expected number of bytes (1), returned {} instead", static_cast<ssize_t>(ret)));
+        FAIL(ByteString::formatted("mbrtowc did not consume the expected number of bytes (1), returned {} instead", static_cast<ssize_t>(ret)));
 
     // Ensure that we are in an initial state again.
     EXPECT(mbsinit(&state) != 0);
diff --git a/Tests/LibCompress/TestBrotli.cpp b/Tests/LibCompress/TestBrotli.cpp
index fcf8ed4a58e..e31a1bcb26e 100644
--- a/Tests/LibCompress/TestBrotli.cpp
+++ b/Tests/LibCompress/TestBrotli.cpp
@@ -13,15 +13,15 @@ static void run_test(StringView const file_name)
 {
     // This makes sure that the tests will run both on target and in Lagom.
 #ifdef AK_OS_SERENITY
-    DeprecatedString path = DeprecatedString::formatted("/usr/Tests/LibCompress/brotli-test-files/{}", file_name);
+    ByteString path = ByteString::formatted("/usr/Tests/LibCompress/brotli-test-files/{}", file_name);
 #else
-    DeprecatedString path = DeprecatedString::formatted("brotli-test-files/{}", file_name);
+    ByteString path = ByteString::formatted("brotli-test-files/{}", file_name);
 #endif
 
     auto cmp_file = MUST(Core::File::open(path, Core::File::OpenMode::Read));
     auto cmp_data = MUST(cmp_file->read_until_eof());
 
-    DeprecatedString path_compressed = DeprecatedString::formatted("{}.br", path);
+    ByteString path_compressed = ByteString::formatted("{}.br", path);
 
     auto file = MUST(Core::File::open(path_compressed, Core::File::OpenMode::Read));
     auto brotli_stream = Compress::BrotliDecompressionStream { MaybeOwned<Stream> { *file } };
@@ -89,12 +89,12 @@ TEST_CASE(brotli_decompress_zero_one_bin)
 {
     // This makes sure that the tests will run both on target and in Lagom.
 #ifdef AK_OS_SERENITY
-    DeprecatedString path = "/usr/Tests/LibCompress/brotli-test-files/zero-one.bin";
+    ByteString path = "/usr/Tests/LibCompress/brotli-test-files/zero-one.bin";
 #else
-    DeprecatedString path = "brotli-test-files/zero-one.bin";
+    ByteString path = "brotli-test-files/zero-one.bin";
 #endif
 
-    DeprecatedString path_compressed = DeprecatedString::formatted("{}.br", path);
+    ByteString path_compressed = ByteString::formatted("{}.br", path);
 
     auto file = MUST(Core::File::open(path_compressed, Core::File::OpenMode::Read));
     auto brotli_stream = Compress::BrotliDecompressionStream { MaybeOwned<Stream> { *file } };
diff --git a/Tests/LibCore/TestLibCoreArgsParser.cpp b/Tests/LibCore/TestLibCoreArgsParser.cpp
index 33635536185..c4bd89792cb 100644
--- a/Tests/LibCore/TestLibCoreArgsParser.cpp
+++ b/Tests/LibCore/TestLibCoreArgsParser.cpp
@@ -115,7 +115,7 @@ TEST_CASE(bool_option)
 TEST_CASE(positional_string_argument)
 {
     // Single required string argument
-    DeprecatedString name = "";
+    ByteString name = "";
     auto parser_result = run_parser({ "app"sv, "buggie"sv }, [&](auto& parser) {
         parser.add_positional_argument(name, "name", "name", Core::ArgsParser::Required::Yes);
     });
diff --git a/Tests/LibCpp/test-cpp-parser.cpp b/Tests/LibCpp/test-cpp-parser.cpp
index fda7cf827ed..a1f8249e8e9 100644
--- a/Tests/LibCpp/test-cpp-parser.cpp
+++ b/Tests/LibCpp/test-cpp-parser.cpp
@@ -13,13 +13,13 @@
 
 constexpr StringView TESTS_ROOT_DIR = "/home/anon/Tests/cpp-tests/parser"sv;
 
-static DeprecatedString read_all(DeprecatedString const& path)
+static ByteString read_all(ByteString const& path)
 {
     auto file = MUST(Core::File::open(path, Core::File::OpenMode::Read));
     auto file_size = MUST(file->size());
     auto content = MUST(ByteBuffer::create_uninitialized(file_size));
     MUST(file->read_until_filled(content.bytes()));
-    return DeprecatedString { content.bytes() };
+    return ByteString { content.bytes() };
 }
 
 TEST_CASE(test_regression)
@@ -32,7 +32,7 @@ TEST_CASE(test_regression)
         outln("Checking {}...", path.basename());
         auto file_path = path.string();
 
-        auto ast_file_path = DeprecatedString::formatted("{}.ast", file_path.substring(0, file_path.length() - sizeof(".cpp") + 1));
+        auto ast_file_path = ByteString::formatted("{}.ast", file_path.substring(0, file_path.length() - sizeof(".cpp") + 1));
 
         auto source = read_all(file_path);
         auto target_ast = read_all(ast_file_path);
@@ -68,7 +68,7 @@ TEST_CASE(test_regression)
 
         fclose(input_stream);
 
-        DeprecatedString content { reinterpret_cast<char const*>(buffer.data()), buffer.size() };
+        ByteString content { reinterpret_cast<char const*>(buffer.data()), buffer.size() };
 
         auto equal = content == target_ast;
         EXPECT(equal);
diff --git a/Tests/LibCpp/test-cpp-preprocessor.cpp b/Tests/LibCpp/test-cpp-preprocessor.cpp
index 89685aff749..51bea505df3 100644
--- a/Tests/LibCpp/test-cpp-preprocessor.cpp
+++ b/Tests/LibCpp/test-cpp-preprocessor.cpp
@@ -12,13 +12,13 @@
 
 constexpr StringView TESTS_ROOT_DIR = "/home/anon/Tests/cpp-tests/preprocessor"sv;
 
-static DeprecatedString read_all(DeprecatedString const& path)
+static ByteString read_all(ByteString const& path)
 {
     auto file = MUST(Core::File::open(path, Core::File::OpenMode::Read));
     auto file_size = MUST(file->size());
     auto content = MUST(ByteBuffer::create_uninitialized(file_size));
     MUST(file->read_until_filled(content.bytes()));
-    return DeprecatedString { content.bytes() };
+    return ByteString { content.bytes() };
 }
 
 TEST_CASE(test_regression)
@@ -31,7 +31,7 @@ TEST_CASE(test_regression)
         outln("Checking {}...", path.basename());
         auto file_path = path.string();
 
-        auto ast_file_path = DeprecatedString::formatted("{}.txt", file_path.substring(0, file_path.length() - sizeof(".cpp") + 1));
+        auto ast_file_path = ByteString::formatted("{}.txt", file_path.substring(0, file_path.length() - sizeof(".cpp") + 1));
 
         auto source = read_all(file_path);
         auto target = read_all(ast_file_path);
@@ -44,7 +44,7 @@ TEST_CASE(test_regression)
 
         EXPECT_EQ(tokens.size(), target_lines.size());
         for (size_t i = 0; i < tokens.size(); ++i) {
-            EXPECT_EQ(tokens[i].to_deprecated_string(), target_lines[i]);
+            EXPECT_EQ(tokens[i].to_byte_string(), target_lines[i]);
         }
         return IterationDecision::Continue;
     }));
diff --git a/Tests/LibCrypto/TestChecksum.cpp b/Tests/LibCrypto/TestChecksum.cpp
index 5faa6281dc0..a3a41ac9eaf 100644
--- a/Tests/LibCrypto/TestChecksum.cpp
+++ b/Tests/LibCrypto/TestChecksum.cpp
@@ -15,11 +15,11 @@ TEST_CASE(test_adler32)
         EXPECT_EQ(digest, expected_result);
     };
 
-    do_test(DeprecatedString("").bytes(), 0x1);
-    do_test(DeprecatedString("a").bytes(), 0x00620062);
-    do_test(DeprecatedString("abc").bytes(), 0x024d0127);
-    do_test(DeprecatedString("message digest").bytes(), 0x29750586);
-    do_test(DeprecatedString("abcdefghijklmnopqrstuvwxyz").bytes(), 0x90860b20);
+    do_test(ByteString("").bytes(), 0x1);
+    do_test(ByteString("a").bytes(), 0x00620062);
+    do_test(ByteString("abc").bytes(), 0x024d0127);
+    do_test(ByteString("message digest").bytes(), 0x29750586);
+    do_test(ByteString("abcdefghijklmnopqrstuvwxyz").bytes(), 0x90860b20);
 }
 
 TEST_CASE(test_crc32)
@@ -29,7 +29,7 @@ TEST_CASE(test_crc32)
         EXPECT_EQ(digest, expected_result);
     };
 
-    do_test(DeprecatedString("").bytes(), 0x0);
-    do_test(DeprecatedString("The quick brown fox jumps over the lazy dog").bytes(), 0x414FA339);
-    do_test(DeprecatedString("various CRC algorithms input data").bytes(), 0x9BD366AE);
+    do_test(ByteString("").bytes(), 0x0);
+    do_test(ByteString("The quick brown fox jumps over the lazy dog").bytes(), 0x414FA339);
+    do_test(ByteString("various CRC algorithms input data").bytes(), 0x9BD366AE);
 }
diff --git a/Tests/LibELF/test-elf.cpp b/Tests/LibELF/test-elf.cpp
index 70c0b106c07..e808c50263b 100644
--- a/Tests/LibELF/test-elf.cpp
+++ b/Tests/LibELF/test-elf.cpp
@@ -58,8 +58,8 @@ TEST_CASE(test_interp_header_tiny_p_filesz)
     int nwritten = write(fd, buffer, sizeof(buffer));
     EXPECT(nwritten);
 
-    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
-    auto elf_path = elf_path_string.to_deprecated_string();
+    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+    auto elf_path = elf_path_string.to_byte_string();
     EXPECT(elf_path.characters());
 
     int rc = execl(elf_path.characters(), "test-elf", nullptr);
@@ -113,8 +113,8 @@ TEST_CASE(test_interp_header_p_filesz_larger_than_p_memsz)
     int nwritten = write(fd, buffer, sizeof(buffer));
     EXPECT(nwritten);
 
-    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
-    auto elf_path = elf_path_string.to_deprecated_string();
+    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+    auto elf_path = elf_path_string.to_byte_string();
     EXPECT(elf_path.characters());
 
     int rc = execl(elf_path.characters(), "test-elf", nullptr);
@@ -172,8 +172,8 @@ TEST_CASE(test_interp_header_p_filesz_plus_p_offset_overflow_p_memsz)
     int nwritten = write(fd, buffer, sizeof(buffer));
     EXPECT(nwritten);
 
-    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
-    auto elf_path = elf_path_string.to_deprecated_string();
+    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+    auto elf_path = elf_path_string.to_byte_string();
     EXPECT(elf_path.characters());
 
     int rc = execl(elf_path.characters(), "test-elf", nullptr);
@@ -228,8 +228,8 @@ TEST_CASE(test_load_header_p_memsz_zero)
     int nwritten = write(fd, buffer, sizeof(buffer));
     EXPECT(nwritten);
 
-    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
-    auto elf_path = elf_path_string.to_deprecated_string();
+    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+    auto elf_path = elf_path_string.to_byte_string();
     EXPECT(elf_path.characters());
 
     int rc = execl(elf_path.characters(), "test-elf", nullptr);
@@ -284,8 +284,8 @@ TEST_CASE(test_load_header_p_memsz_not_equal_to_p_align)
     int nwritten = write(fd, buffer, sizeof(buffer));
     EXPECT(nwritten);
 
-    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(DeprecatedString::formatted("/proc/{}/fd/{}", getpid(), fd)));
-    auto elf_path = elf_path_string.to_deprecated_string();
+    auto elf_path_string = TRY_OR_FAIL(FileSystem::read_link(ByteString::formatted("/proc/{}/fd/{}", getpid(), fd)));
+    auto elf_path = elf_path_string.to_byte_string();
     EXPECT(elf_path.characters());
 
     int rc = execl(elf_path.characters(), "test-elf", nullptr);
diff --git a/Tests/LibGL/TestRender.cpp b/Tests/LibGL/TestRender.cpp
index a69e14f7259..3c4cddeac05 100644
--- a/Tests/LibGL/TestRender.cpp
+++ b/Tests/LibGL/TestRender.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <LibCore/File.h>
 #include <LibGL/GL/gl.h>
@@ -31,7 +31,7 @@ static NonnullOwnPtr<GL::GLContext> create_testing_context(int width, int height
 
 static void expect_bitmap_equals_reference(Gfx::Bitmap const& bitmap, StringView test_name)
 {
-    auto reference_filename = DeprecatedString::formatted("{}.qoi", test_name);
+    auto reference_filename = ByteString::formatted("{}.qoi", test_name);
 
     if constexpr (SAVE_OUTPUT) {
         auto target_path = LexicalPath("/home/anon").append(reference_filename);
@@ -40,7 +40,7 @@ static void expect_bitmap_equals_reference(Gfx::Bitmap const& bitmap, StringView
         MUST(qoi_output_stream->write_until_depleted(qoi_buffer));
     }
 
-    auto reference_image_path = DeprecatedString::formatted(REFERENCE_IMAGE_DIR "/{}", reference_filename);
+    auto reference_image_path = ByteString::formatted(REFERENCE_IMAGE_DIR "/{}", reference_filename);
     auto reference_bitmap = MUST(Gfx::Bitmap::load_from_file(reference_image_path));
     EXPECT_EQ(reference_bitmap->visually_equals(bitmap), true);
 }
diff --git a/Tests/LibGLSL/test-parser.cpp b/Tests/LibGLSL/test-parser.cpp
index 2a32a514fef..26fcecc4b3b 100644
--- a/Tests/LibGLSL/test-parser.cpp
+++ b/Tests/LibGLSL/test-parser.cpp
@@ -28,7 +28,7 @@ TEST_CASE(test_regression)
             return IterationDecision::Continue;
 
         outln("Checking {}...", path.basename());
-        String file_path = MUST(String::from_deprecated_string(path.string()));
+        String file_path = MUST(String::from_byte_string(path.string()));
 
         auto ast_file_path = MUST(String::formatted("{}.ast", MUST(file_path.substring_from_byte_offset(0, file_path.bytes_as_string_view().length() - sizeof(".glsl") + 1))));
 
diff --git a/Tests/LibGfx/TestImageDecoder.cpp b/Tests/LibGfx/TestImageDecoder.cpp
index 796f8ed5927..a30626bca84 100644
--- a/Tests/LibGfx/TestImageDecoder.cpp
+++ b/Tests/LibGfx/TestImageDecoder.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/MappedFile.h>
 #include <LibGfx/ImageFormats/BMPLoader.h>
 #include <LibGfx/ImageFormats/DDSLoader.h>
diff --git a/Tests/LibIMAP/TestQuotedPrintable.cpp b/Tests/LibIMAP/TestQuotedPrintable.cpp
index 9a97ce61caa..4b392c2087b 100644
--- a/Tests/LibIMAP/TestQuotedPrintable.cpp
+++ b/Tests/LibIMAP/TestQuotedPrintable.cpp
@@ -44,7 +44,7 @@ TEST_CASE(test_decode)
             illegal_character_builder.append(byte);
     }
 
-    auto illegal_character_decode = MUST(IMAP::decode_quoted_printable(illegal_character_builder.to_deprecated_string()));
+    auto illegal_character_decode = MUST(IMAP::decode_quoted_printable(illegal_character_builder.to_byte_string()));
     EXPECT(illegal_character_decode.is_empty());
 
     // If an escape sequence is invalid the characters are output unaltered. Illegal characters are ignored as usual.
diff --git a/Tests/LibJS/test-js.cpp b/Tests/LibJS/test-js.cpp
index 86174d778bf..bed738fe2d1 100644
--- a/Tests/LibJS/test-js.cpp
+++ b/Tests/LibJS/test-js.cpp
@@ -22,7 +22,7 @@ TESTJS_GLOBAL_FUNCTION(is_strict_mode, isStrictMode, 0)
 
 TESTJS_GLOBAL_FUNCTION(can_parse_source, canParseSource)
 {
-    auto source = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto source = TRY(vm.argument(0).to_byte_string(vm));
     auto parser = JS::Parser(JS::Lexer(source));
     (void)parser.parse_program();
     return JS::Value(!parser.has_errors());
@@ -65,14 +65,14 @@ TESTJS_GLOBAL_FUNCTION(mark_as_garbage, markAsGarbage)
         return execution_context->lexical_environment != nullptr;
     });
     if (!outer_environment.has_value())
-        return vm.throw_completion<JS::ReferenceError>(JS::ErrorType::UnknownIdentifier, variable_name.deprecated_string());
+        return vm.throw_completion<JS::ReferenceError>(JS::ErrorType::UnknownIdentifier, variable_name.byte_string());
 
-    auto reference = TRY(vm.resolve_binding(variable_name.deprecated_string(), outer_environment.value()->lexical_environment));
+    auto reference = TRY(vm.resolve_binding(variable_name.byte_string(), outer_environment.value()->lexical_environment));
 
     auto value = TRY(reference.get_value(vm));
 
     if (!can_be_held_weakly(value))
-        return vm.throw_completion<JS::TypeError>(JS::ErrorType::CannotBeHeldWeakly, DeprecatedString::formatted("Variable with name {}", variable_name.deprecated_string()));
+        return vm.throw_completion<JS::TypeError>(JS::ErrorType::CannotBeHeldWeakly, ByteString::formatted("Variable with name {}", variable_name.byte_string()));
 
     vm.heap().uproot_cell(&value.as_cell());
     TRY(reference.delete_(vm));
@@ -111,7 +111,7 @@ TESTJS_GLOBAL_FUNCTION(set_time_zone, setTimeZone)
     return current_time_zone;
 }
 
-TESTJS_RUN_FILE_FUNCTION(DeprecatedString const& test_file, JS::Realm& realm, JS::ExecutionContext&)
+TESTJS_RUN_FILE_FUNCTION(ByteString const& test_file, JS::Realm& realm, JS::ExecutionContext&)
 {
     if (!test262_parser_tests)
         return Test::JS::RunFileHookResult::RunAsNormal;
@@ -146,8 +146,8 @@ TESTJS_RUN_FILE_FUNCTION(DeprecatedString const& test_file, JS::Realm& realm, JS
         parse_succeeded = !Test::JS::parse_script(test_file, realm).is_error();
 
     bool test_passed = true;
-    DeprecatedString message;
-    DeprecatedString expectation_string;
+    ByteString message;
+    ByteString expectation_string;
 
     switch (expectation) {
     case Early:
diff --git a/Tests/LibJS/test-test262.cpp b/Tests/LibJS/test-test262.cpp
index 43e5d481fa2..cbb8d2082a8 100644
--- a/Tests/LibJS/test-test262.cpp
+++ b/Tests/LibJS/test-test262.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/HashMap.h>
 #include <AK/JsonObject.h>
@@ -107,7 +107,7 @@ static StringView emoji_for_result(TestResult result)
 
 static constexpr StringView total_test_emoji = "🧪"sv;
 
-static ErrorOr<HashMap<size_t, TestResult>> run_test_files(Span<DeprecatedString> files, size_t offset, StringView command, char const* const arguments[])
+static ErrorOr<HashMap<size_t, TestResult>> run_test_files(Span<ByteString> files, size_t offset, StringView command, char const* const arguments[])
 {
     HashMap<size_t, TestResult> results {};
     TRY(results.try_ensure_capacity(files.size()));
@@ -133,12 +133,12 @@ static ErrorOr<HashMap<size_t, TestResult>> run_test_files(Span<DeprecatedString
         }
 
         auto output_or_error = runner_process->read_all();
-        DeprecatedString output;
+        ByteString output;
 
         if (output_or_error.is_error())
             warnln("Got error: {} while reading runner output", output_or_error.error());
         else
-            output = DeprecatedString(output_or_error.release_value().standard_error.bytes(), Chomp);
+            output = ByteString(output_or_error.release_value().standard_error.bytes(), Chomp);
 
         auto status_or_error = runner_process->status();
         bool failed = false;
@@ -162,7 +162,7 @@ static ErrorOr<HashMap<size_t, TestResult>> run_test_files(Span<DeprecatedString
             auto result_object_or_error = parser.parse();
             if (!result_object_or_error.is_error() && result_object_or_error.value().is_object()) {
                 auto& result_object = result_object_or_error.value().as_object();
-                if (auto result_string = result_object.get_deprecated_string("result"sv); result_string.has_value()) {
+                if (auto result_string = result_object.get_byte_string("result"sv); result_string.has_value()) {
                     auto const& view = result_string.value();
                     // Timeout and assert fail already are the result of the stopping test
                     if (view == "timeout"sv || view == "assert_fail"sv) {
@@ -190,7 +190,7 @@ static ErrorOr<HashMap<size_t, TestResult>> run_test_files(Span<DeprecatedString
     return results;
 }
 
-void write_per_file(HashMap<size_t, TestResult> const& result_map, Vector<DeprecatedString> const& paths, StringView per_file_name, double time_taken_in_ms);
+void write_per_file(HashMap<size_t, TestResult> const& result_map, Vector<ByteString> const& paths, StringView per_file_name, double time_taken_in_ms);
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
@@ -213,12 +213,12 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.parse(arguments);
 
     // Normalize the path to ensure filenames are consistent
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
 
     if (!FileSystem::is_directory(test_directory)) {
         paths.append(test_directory);
     } else {
-        Test::iterate_directory_recursively(LexicalPath::canonicalized_path(test_directory), [&](DeprecatedString const& file_path) {
+        Test::iterate_directory_recursively(LexicalPath::canonicalized_path(test_directory), [&](ByteString const& file_path) {
             if (file_path.contains("_FIXTURE"sv))
                 return;
             // FIXME: Add ignored file set
@@ -230,7 +230,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     outln("Found {} tests", paths.size());
 
     auto parameters = pass_through_parameters.split_view(' ');
-    Vector<DeprecatedString> args;
+    Vector<ByteString> args;
     args.ensure_capacity(parameters.size() + 2);
     args.append(runner_command);
     if (!dont_disable_core_dump)
@@ -301,7 +301,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     return 0;
 }
 
-void write_per_file(HashMap<size_t, TestResult> const& result_map, Vector<DeprecatedString> const& paths, StringView per_file_name, double time_taken_in_ms)
+void write_per_file(HashMap<size_t, TestResult> const& result_map, Vector<ByteString> const& paths, StringView per_file_name, double time_taken_in_ms)
 {
 
     auto file_or_error = Core::File::open(per_file_name, Core::File::OpenMode::Write);
@@ -320,7 +320,7 @@ void write_per_file(HashMap<size_t, TestResult> const& result_map, Vector<Deprec
     complete_results.set("duration", time_taken_in_ms / 1000.);
     complete_results.set("results", result_object);
 
-    if (file->write_until_depleted(complete_results.to_deprecated_string().bytes()).is_error())
+    if (file->write_until_depleted(complete_results.to_byte_string().bytes()).is_error())
         warnln("Failed to write per-file");
     file->close();
 }
diff --git a/Tests/LibJS/test262-runner.cpp b/Tests/LibJS/test262-runner.cpp
index ef87d86fad2..83e1faedd40 100644
--- a/Tests/LibJS/test262-runner.cpp
+++ b/Tests/LibJS/test262-runner.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/JsonObject.h>
 #include <AK/Result.h>
@@ -32,9 +32,9 @@
 #    include <sys/prctl.h>
 #endif
 
-static DeprecatedString s_current_test = "";
+static ByteString s_current_test = "";
 static bool s_parse_only = false;
-static DeprecatedString s_harness_file_directory;
+static ByteString s_harness_file_directory;
 static bool s_automatic_harness_detection_mode = false;
 
 enum class NegativePhase {
@@ -46,9 +46,9 @@ enum class NegativePhase {
 
 struct TestError {
     NegativePhase phase { NegativePhase::ParseOrEarly };
-    DeprecatedString type;
-    DeprecatedString details;
-    DeprecatedString harness_file;
+    ByteString type;
+    ByteString details;
+    ByteString harness_file;
 };
 
 using ScriptOrModuleProgram = Variant<JS::NonnullGCPtr<JS::Script>, JS::NonnullGCPtr<JS::SourceTextModule>>;
@@ -61,7 +61,7 @@ static Result<ScriptOrModuleProgram, TestError> parse_program(JS::Realm& realm,
         return TestError {
             NegativePhase::ParseOrEarly,
             "SyntaxError",
-            script_or_error.error()[0].to_deprecated_string(),
+            script_or_error.error()[0].to_byte_string(),
             ""
         };
     }
@@ -92,39 +92,39 @@ static Result<void, TestError> run_program(InterpreterT& interpreter, ScriptOrMo
 
             auto name = object.get_without_side_effects("name");
             if (!name.is_empty() && !name.is_accessor()) {
-                error.type = name.to_string_without_side_effects().to_deprecated_string();
+                error.type = name.to_string_without_side_effects().to_byte_string();
             } else {
                 auto constructor = object.get_without_side_effects("constructor");
                 if (constructor.is_object()) {
                     name = constructor.as_object().get_without_side_effects("name");
                     if (!name.is_undefined())
-                        error.type = name.to_string_without_side_effects().to_deprecated_string();
+                        error.type = name.to_string_without_side_effects().to_byte_string();
                 }
             }
 
             auto message = object.get_without_side_effects("message");
             if (!message.is_empty() && !message.is_accessor())
-                error.details = message.to_string_without_side_effects().to_deprecated_string();
+                error.details = message.to_string_without_side_effects().to_byte_string();
         }
         if (error.type.is_empty())
-            error.type = error_value.to_string_without_side_effects().to_deprecated_string();
+            error.type = error_value.to_string_without_side_effects().to_byte_string();
         return error;
     }
     return {};
 }
 
-static HashMap<DeprecatedString, DeprecatedString> s_cached_harness_files;
+static HashMap<ByteString, ByteString> s_cached_harness_files;
 
 static Result<StringView, TestError> read_harness_file(StringView harness_file)
 {
     auto cache = s_cached_harness_files.find(harness_file);
     if (cache == s_cached_harness_files.end()) {
-        auto file_or_error = Core::File::open(DeprecatedString::formatted("{}{}", s_harness_file_directory, harness_file), Core::File::OpenMode::Read);
+        auto file_or_error = Core::File::open(ByteString::formatted("{}{}", s_harness_file_directory, harness_file), Core::File::OpenMode::Read);
         if (file_or_error.is_error()) {
             return TestError {
                 NegativePhase::Harness,
                 "filesystem",
-                DeprecatedString::formatted("Could not open file: {}", harness_file),
+                ByteString::formatted("Could not open file: {}", harness_file),
                 harness_file
             };
         }
@@ -134,13 +134,13 @@ static Result<StringView, TestError> read_harness_file(StringView harness_file)
             return TestError {
                 NegativePhase::Harness,
                 "filesystem",
-                DeprecatedString::formatted("Could not read file: {}", harness_file),
+                ByteString::formatted("Could not read file: {}", harness_file),
                 harness_file
             };
         }
 
         StringView contents_view = contents_or_error.value();
-        s_cached_harness_files.set(harness_file, contents_view.to_deprecated_string());
+        s_cached_harness_files.set(harness_file, contents_view.to_byte_string());
         cache = s_cached_harness_files.find(harness_file);
         VERIFY(cache != s_cached_harness_files.end());
     }
@@ -206,7 +206,7 @@ static Result<void, TestError> run_test(StringView source, StringView filepath,
             return TestError {
                 NegativePhase::ParseOrEarly,
                 "SyntaxError",
-                parser.errors()[0].to_deprecated_string(),
+                parser.errors()[0].to_byte_string(),
                 ""
             };
         }
@@ -250,14 +250,14 @@ static Result<void, TestError> run_test(StringView source, StringView filepath,
     return run_program(vm->bytecode_interpreter(), program_or_error.value());
 }
 
-static Result<TestMetadata, DeprecatedString> extract_metadata(StringView source)
+static Result<TestMetadata, ByteString> extract_metadata(StringView source)
 {
     auto lines = source.lines();
 
     TestMetadata metadata;
 
     bool parsing_negative = false;
-    DeprecatedString failed_message;
+    ByteString failed_message;
 
     auto parse_list = [&](StringView line) {
         auto start = line.find('[');
@@ -268,7 +268,7 @@ static Result<TestMetadata, DeprecatedString> extract_metadata(StringView source
 
         auto end = line.find_last(']');
         if (!end.has_value() || end.value() <= start.value()) {
-            failed_message = DeprecatedString::formatted("Can't parse list in '{}'", line);
+            failed_message = ByteString::formatted("Can't parse list in '{}'", line);
             return items;
         }
 
@@ -281,7 +281,7 @@ static Result<TestMetadata, DeprecatedString> extract_metadata(StringView source
     auto second_word = [&](StringView line) {
         auto separator = line.find(' ');
         if (!separator.has_value() || separator.value() >= (line.length() - 1u)) {
-            failed_message = DeprecatedString::formatted("Can't parse value after space in '{}'", line);
+            failed_message = ByteString::formatted("Can't parse value after space in '{}'", line);
             return ""sv;
         }
         return line.substring_view(separator.value() + 1);
@@ -335,7 +335,7 @@ static Result<TestMetadata, DeprecatedString> extract_metadata(StringView source
                     metadata.phase = NegativePhase::Runtime;
                 } else {
                     has_phase = false;
-                    failed_message = DeprecatedString::formatted("Unknown negative phase: {}", phase);
+                    failed_message = ByteString::formatted("Unknown negative phase: {}", phase);
                     break;
                 }
             } else if (line.starts_with("type:"sv)) {
@@ -392,7 +392,7 @@ static Result<TestMetadata, DeprecatedString> extract_metadata(StringView source
     }
 
     if (failed_message.is_empty())
-        failed_message = DeprecatedString::formatted("Never reached end of comment '---*/'");
+        failed_message = ByteString::formatted("Never reached end of comment '---*/'");
 
     return failed_message;
 }
@@ -416,7 +416,7 @@ static bool verify_test(Result<void, TestError>& result, TestMetadata const& met
     }
 
     if (metadata.is_async && output.has("output"sv)) {
-        auto output_messages = output.get_deprecated_string("output"sv);
+        auto output_messages = output.get_byte_string("output"sv);
         VERIFY(output_messages.has_value());
         if (output_messages->contains("AsyncTestFailure:InternalError: TODO("sv)) {
             output.set("todo_error", true);
@@ -467,7 +467,7 @@ static bool verify_test(Result<void, TestError>& result, TestMetadata const& met
 
     JsonObject expected_error_object;
     expected_error_object.set("phase", phase_to_string(metadata.phase));
-    expected_error_object.set("type", metadata.type.to_deprecated_string());
+    expected_error_object.set("type", metadata.type.to_byte_string());
 
     expected_error = expected_error_object;
 
@@ -506,7 +506,7 @@ static bool verify_test(Result<void, TestError>& result, TestMetadata const& met
     return error.phase == metadata.phase && error.type == metadata.type;
 }
 
-static bool extract_harness_directory(DeprecatedString const& test_file_path)
+static bool extract_harness_directory(ByteString const& test_file_path)
 {
     auto test_directory_index = test_file_path.find("test/"sv);
     if (!test_directory_index.has_value()) {
@@ -514,7 +514,7 @@ static bool extract_harness_directory(DeprecatedString const& test_file_path)
         return false;
     }
 
-    s_harness_file_directory = DeprecatedString::formatted("{}harness/", test_file_path.substring_view(0, test_directory_index.value()));
+    s_harness_file_directory = ByteString::formatted("{}harness/", test_file_path.substring_view(0, test_directory_index.value()));
     return true;
 }
 
@@ -532,7 +532,7 @@ static bool g_in_assert = false;
         assert_fail_result.set("assert_fail", true);
         assert_fail_result.set("result", "assert_fail");
         assert_fail_result.set("output", assert_failed_message);
-        outln(saved_stdout_fd, "RESULT {}{}", assert_fail_result.to_deprecated_string(), '\0');
+        outln(saved_stdout_fd, "RESULT {}{}", assert_fail_result.to_byte_string(), '\0');
         // (Attempt to) Ensure that messages are written before quitting.
         fflush(saved_stdout_fd);
         fflush(stderr);
@@ -555,7 +555,7 @@ extern "C" __attribute__((__noreturn__)) void __assert_fail(char const* assertio
 extern "C" __attribute__((__noreturn__)) void __assert_fail(char const* assertion, char const* file, unsigned int line, char const* function)
 #    endif
 {
-    auto full_message = DeprecatedString::formatted("{}:{}: {}: Assertion `{}' failed.", file, line, function, assertion);
+    auto full_message = ByteString::formatted("{}:{}: {}: Assertion `{}' failed.", file, line, function, assertion);
     handle_failed_assert(full_message.characters());
 }
 #endif
@@ -598,7 +598,7 @@ int main(int argc, char** argv)
     if (s_harness_file_directory.is_empty()) {
         s_automatic_harness_detection_mode = true;
     } else if (!s_harness_file_directory.ends_with('/')) {
-        s_harness_file_directory = DeprecatedString::formatted("{}/", s_harness_file_directory);
+        s_harness_file_directory = ByteString::formatted("{}/", s_harness_file_directory);
     }
 
     if (timeout <= 0) {
@@ -651,10 +651,10 @@ int main(int argc, char** argv)
     auto collect_output = [&] {
         fflush(stdout);
         auto nread = read(stdout_pipe[0], buffer, BUFFER_SIZE);
-        Optional<DeprecatedString> value;
+        Optional<ByteString> value;
 
         if (nread > 0) {
-            value = DeprecatedString { buffer, static_cast<size_t>(nread) };
+            value = ByteString { buffer, static_cast<size_t>(nread) };
             while (nread > 0) {
                 nread = read(stdout_pipe[0], buffer, BUFFER_SIZE);
             }
@@ -707,7 +707,7 @@ int main(int argc, char** argv)
 
         count++;
 
-        DeprecatedString source_with_strict;
+        ByteString source_with_strict;
         static StringView use_strict = "'use strict';\n"sv;
         static size_t strict_length = use_strict.length();
 
@@ -721,7 +721,7 @@ int main(int argc, char** argv)
             StringBuilder builder { contents.size() + strict_length };
             builder.append(use_strict);
             builder.append(contents);
-            source_with_strict = builder.to_deprecated_string();
+            source_with_strict = builder.to_byte_string();
         }
 
         StringView with_strict = source_with_strict.view();
@@ -731,7 +731,7 @@ int main(int argc, char** argv)
         result_object.set("test", path);
 
         ScopeGuard output_guard = [&] {
-            outln(saved_stdout_fd, "RESULT {}{}", result_object.to_deprecated_string(), '\0');
+            outln(saved_stdout_fd, "RESULT {}{}", result_object.to_byte_string(), '\0');
             fflush(saved_stdout_fd);
         };
 
diff --git a/Tests/LibMarkdown/TestCommonmark.cpp b/Tests/LibMarkdown/TestCommonmark.cpp
index 9c748197dc6..56372b79249 100644
--- a/Tests/LibMarkdown/TestCommonmark.cpp
+++ b/Tests/LibMarkdown/TestCommonmark.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/JsonArray.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonParser.h>
@@ -23,20 +23,20 @@ TEST_SETUP
     auto file_size = MUST(file->size());
     auto content = MUST(ByteBuffer::create_uninitialized(file_size));
     MUST(file->read_until_filled(content.bytes()));
-    DeprecatedString test_data { content.bytes() };
+    ByteString test_data { content.bytes() };
 
     auto tests = JsonParser(test_data).parse().value().as_array();
     for (size_t i = 0; i < tests.size(); ++i) {
         auto testcase = tests[i].as_object();
 
-        auto name = DeprecatedString::formatted("{}_ex{}_{}..{}",
+        auto name = ByteString::formatted("{}_ex{}_{}..{}",
             testcase.get("section"sv).value(),
             testcase.get("example"sv).value(),
             testcase.get("start_line"sv).value(),
             testcase.get("end_line"sv).value());
 
-        DeprecatedString markdown = testcase.get_deprecated_string("markdown"sv).value();
-        DeprecatedString html = testcase.get_deprecated_string("html"sv).value();
+        ByteString markdown = testcase.get_byte_string("markdown"sv).value();
+        ByteString html = testcase.get_byte_string("html"sv).value();
 
         Test::TestSuite::the().add_case(adopt_ref(*new Test::TestCase(
             name, [markdown, html]() {
diff --git a/Tests/LibPDF/TestPDF.cpp b/Tests/LibPDF/TestPDF.cpp
index da721d032ac..450e8d71762 100644
--- a/Tests/LibPDF/TestPDF.cpp
+++ b/Tests/LibPDF/TestPDF.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <LibCore/MappedFile.h>
 #include <LibPDF/CommonNames.h>
@@ -65,7 +65,7 @@ TEST_CASE(encodig)
 
 TEST_CASE(truncated_pdf_header_issue_10717)
 {
-    AK::DeprecatedString string { "%PDF-2.11%" };
+    AK::ByteString string { "%PDF-2.11%" };
     auto document = PDF::Document::create(string.bytes());
     EXPECT(document.is_error());
 }
diff --git a/Tests/LibRegex/Regex.cpp b/Tests/LibRegex/Regex.cpp
index 76b217b98fa..555def1b56d 100644
--- a/Tests/LibRegex/Regex.cpp
+++ b/Tests/LibRegex/Regex.cpp
@@ -122,7 +122,7 @@ TEST_CASE(regex_lexer)
 
 TEST_CASE(parser_error_parens)
 {
-    DeprecatedString pattern = "test()test";
+    ByteString pattern = "test()test";
     Lexer l(pattern);
     PosixExtendedParser p(l);
     p.parse();
@@ -132,7 +132,7 @@ TEST_CASE(parser_error_parens)
 
 TEST_CASE(parser_error_special_characters_used_at_wrong_place)
 {
-    DeprecatedString pattern;
+    ByteString pattern;
     Vector<char, 5> chars = { '*', '+', '?', '{' };
     StringBuilder b;
 
@@ -143,7 +143,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         // First in ere
         b.clear();
         b.append(ch);
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         l.set_source(pattern);
         p.parse();
         EXPECT(p.has_error());
@@ -153,7 +153,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         b.clear();
         b.append("a|"sv);
         b.append(ch);
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         l.set_source(pattern);
         p.parse();
         EXPECT(p.has_error());
@@ -163,7 +163,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         b.clear();
         b.append('^');
         b.append(ch);
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         l.set_source(pattern);
         p.parse();
         EXPECT(p.has_error());
@@ -173,7 +173,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         b.clear();
         b.append('$');
         b.append(ch);
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         l.set_source(pattern);
         p.parse();
         EXPECT(p.has_error());
@@ -184,7 +184,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         b.append('(');
         b.append(ch);
         b.append(')');
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         l.set_source(pattern);
         p.parse();
         EXPECT(p.has_error());
@@ -267,7 +267,7 @@ TEST_CASE(catch_all_newline)
     Regex<PosixExtended> re("^.*$", PosixFlags::Multiline | PosixFlags::StringCopyMatches);
     RegexResult result;
     auto lambda = [&result, &re]() {
-        DeprecatedString aaa = "Hello World\nTest\n1234\n";
+        ByteString aaa = "Hello World\nTest\n1234\n";
         result = match(aaa, re);
         EXPECT_EQ(result.success, true);
     };
@@ -283,11 +283,11 @@ TEST_CASE(catch_all_newline_view)
     Regex<PosixExtended> re("^.*$", PosixFlags::Multiline);
     RegexResult result;
 
-    DeprecatedString aaa = "Hello World\nTest\n1234\n";
+    ByteString aaa = "Hello World\nTest\n1234\n";
     result = match(aaa, re);
     EXPECT_EQ(result.success, true);
     EXPECT_EQ(result.count, 3u);
-    DeprecatedString str = "Hello World";
+    ByteString str = "Hello World";
     EXPECT_EQ(result.matches.at(0).view, str.view());
     EXPECT_EQ(result.matches.at(1).view, "Test");
     EXPECT_EQ(result.matches.at(2).view, "1234");
@@ -313,7 +313,7 @@ TEST_CASE(catch_all_newline_2)
 TEST_CASE(match_all_character_class)
 {
     Regex<PosixExtended> re("[[:alpha:]]");
-    DeprecatedString str = "[Window]\nOpacity=255\nAudibleBeep=0\n";
+    ByteString str = "[Window]\nOpacity=255\nAudibleBeep=0\n";
     RegexResult result = match(str, re, PosixFlags::Global | PosixFlags::StringCopyMatches);
 
     EXPECT_EQ(result.success, true);
@@ -326,7 +326,7 @@ TEST_CASE(match_all_character_class)
 TEST_CASE(match_character_class_with_assertion)
 {
     Regex<PosixExtended> re("[[:alpha:]]+$");
-    DeprecatedString str = "abcdef";
+    ByteString str = "abcdef";
     RegexResult result = match(str, re);
 
     EXPECT_EQ(result.success, true);
@@ -372,13 +372,13 @@ TEST_CASE(ini_file_entries)
         regex_dbg.print_bytecode(re);
     }
 
-    DeprecatedString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
+    ByteString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
     EXPECT_EQ(re.search(haystack.view(), result, PosixFlags::Multiline), true);
     EXPECT_EQ(result.count, 3u);
 
     if constexpr (REGEX_DEBUG) {
         for (auto& v : result.matches)
-            fprintf(stderr, "%s\n", v.view.to_deprecated_string().characters());
+            fprintf(stderr, "%s\n", v.view.to_byte_string().characters());
     }
 
     EXPECT_EQ(result.matches.at(0).view, "[Window]");
@@ -400,7 +400,7 @@ TEST_CASE(ini_file_entries2)
     Regex<PosixExtended> re("[[:alpha:]]*=([[:digit:]]*)");
     RegexResult result;
 
-    DeprecatedString haystack = "ViewMode=Icon";
+    ByteString haystack = "ViewMode=Icon";
 
     EXPECT_EQ(re.match(haystack.view(), result), false);
     EXPECT_EQ(result.count, 0u);
@@ -421,7 +421,7 @@ TEST_CASE(named_capture_group)
         regex_dbg.print_bytecode(re);
     }
 
-    DeprecatedString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
+    ByteString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
     EXPECT_EQ(re.search(haystack, result, PosixFlags::Multiline), true);
     EXPECT_EQ(result.count, 2u);
     EXPECT_EQ(result.matches.at(0).view, "Opacity=255");
@@ -444,7 +444,7 @@ TEST_CASE(ecma262_named_capture_group_with_dollar_sign)
         regex_dbg.print_bytecode(re);
     }
 
-    DeprecatedString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
+    ByteString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
     EXPECT_EQ(re.search(haystack, result, ECMAScriptFlags::Multiline), true);
     EXPECT_EQ(result.count, 2u);
     EXPECT_EQ(result.matches.at(0).view, "Opacity=255");
@@ -467,7 +467,7 @@ TEST_CASE(a_star)
         regex_dbg.print_bytecode(re);
     }
 
-    DeprecatedString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
+    ByteString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
     EXPECT_EQ(re.search(haystack.view(), result, PosixFlags::Multiline), true);
     EXPECT_EQ(result.count, 32u);
     if (result.count == 32u) {
@@ -500,7 +500,7 @@ TEST_CASE(posix_extended_nested_capture_group)
     EXPECT_EQ(result.capture_group_matches[0][2].view, "llo"sv);
 }
 
-auto parse_test_case_long_disjunction_chain = DeprecatedString::repeated("a|"sv, 100000);
+auto parse_test_case_long_disjunction_chain = ByteString::repeated("a|"sv, 100000);
 
 TEST_CASE(ECMA262_parse)
 {
@@ -730,7 +730,7 @@ TEST_CASE(ECMA262_unicode_match)
     StringBuilder builder;
     for (u32 code_point : space_and_line_terminator_code_points)
         builder.append_code_point(code_point);
-    auto space_and_line_terminators = builder.to_deprecated_string();
+    auto space_and_line_terminators = builder.to_byte_string();
 
     struct _test {
         StringView pattern;
@@ -969,7 +969,7 @@ TEST_CASE(case_insensitive_match)
 TEST_CASE(extremely_long_fork_chain)
 {
     Regex<ECMA262> re("(?:aa)*");
-    auto result = re.match(DeprecatedString::repeated('a', 1000));
+    auto result = re.match(ByteString::repeated('a', 1000));
     EXPECT_EQ(result.success, true);
 }
 
@@ -988,7 +988,7 @@ TEST_CASE(theoretically_infinite_loop)
     }
 }
 
-static auto g_lots_of_a_s = DeprecatedString::repeated('a', 10'000'000);
+static auto g_lots_of_a_s = ByteString::repeated('a', 10'000'000);
 
 BENCHMARK_CASE(fork_performance)
 {
@@ -1137,7 +1137,7 @@ TEST_CASE(single_match_flag)
         auto result = re.match("ABC"sv);
         EXPECT_EQ(result.success, true);
         EXPECT_EQ(result.matches.size(), 1u);
-        EXPECT_EQ(result.matches.first().view.to_deprecated_string(), "A"sv);
+        EXPECT_EQ(result.matches.first().view.to_byte_string(), "A"sv);
     }
 }
 
@@ -1149,7 +1149,7 @@ TEST_CASE(empty_string_wildcard_match)
         auto result = re.match(""sv);
         EXPECT_EQ(result.success, true);
         EXPECT_EQ(result.matches.size(), 1u);
-        EXPECT_EQ(result.matches.first().view.to_deprecated_string(), ""sv);
+        EXPECT_EQ(result.matches.first().view.to_byte_string(), ""sv);
     }
 }
 
@@ -1162,7 +1162,7 @@ TEST_CASE(inversion_state_in_char_class)
         auto result = re.match("hello"sv);
         EXPECT_EQ(result.success, true);
         EXPECT_EQ(result.matches.size(), 1u);
-        EXPECT_EQ(result.matches.first().view.to_deprecated_string(), "h"sv);
+        EXPECT_EQ(result.matches.first().view.to_byte_string(), "h"sv);
     }
     {
         Regex<ECMA262> re("^(?:([^\\s!\"#%-,\\./;->@\\[-\\^`\\{-~]+(?=([=~}\\s/.)|]))))"sv, ECMAScriptFlags::Global);
@@ -1170,8 +1170,8 @@ TEST_CASE(inversion_state_in_char_class)
         auto result = re.match("slideNumbers}}"sv);
         EXPECT_EQ(result.success, true);
         EXPECT_EQ(result.matches.size(), 1u);
-        EXPECT_EQ(result.matches.first().view.to_deprecated_string(), "slideNumbers"sv);
-        EXPECT_EQ(result.capture_group_matches.first()[0].view.to_deprecated_string(), "slideNumbers"sv);
-        EXPECT_EQ(result.capture_group_matches.first()[1].view.to_deprecated_string(), "}"sv);
+        EXPECT_EQ(result.matches.first().view.to_byte_string(), "slideNumbers"sv);
+        EXPECT_EQ(result.capture_group_matches.first()[0].view.to_byte_string(), "slideNumbers"sv);
+        EXPECT_EQ(result.capture_group_matches.first()[1].view.to_byte_string(), "}"sv);
     }
 }
diff --git a/Tests/LibRegex/RegexLibC.cpp b/Tests/LibRegex/RegexLibC.cpp
index aff5c25fda0..0e98b1d4c5b 100644
--- a/Tests/LibRegex/RegexLibC.cpp
+++ b/Tests/LibRegex/RegexLibC.cpp
@@ -13,7 +13,7 @@
 
 TEST_CASE(catch_all)
 {
-    DeprecatedString pattern = "^.*$";
+    ByteString pattern = "^.*$";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -24,7 +24,7 @@ TEST_CASE(catch_all)
 
 TEST_CASE(simple_start)
 {
-    DeprecatedString pattern = "^hello friends";
+    ByteString pattern = "^hello friends";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -37,7 +37,7 @@ TEST_CASE(simple_start)
 
 TEST_CASE(simple_end)
 {
-    DeprecatedString pattern = ".*hello\\.\\.\\. there$";
+    ByteString pattern = ".*hello\\.\\.\\. there$";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -51,7 +51,7 @@ TEST_CASE(simple_end)
 
 TEST_CASE(simple_period)
 {
-    DeprecatedString pattern = "hello.";
+    ByteString pattern = "hello.";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -65,7 +65,7 @@ TEST_CASE(simple_period)
 
 TEST_CASE(simple_period_end)
 {
-    DeprecatedString pattern = "hello.$";
+    ByteString pattern = "hello.$";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED | REG_NOSUB), REG_NOERR);
@@ -79,7 +79,7 @@ TEST_CASE(simple_period_end)
 
 TEST_CASE(simple_escaped)
 {
-    DeprecatedString pattern = "hello\\.";
+    ByteString pattern = "hello\\.";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -91,7 +91,7 @@ TEST_CASE(simple_escaped)
 
 TEST_CASE(simple_period2_end)
 {
-    DeprecatedString pattern = ".*hi... there$";
+    ByteString pattern = ".*hi... there$";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -106,7 +106,7 @@ TEST_CASE(simple_period2_end)
 
 TEST_CASE(simple_plus)
 {
-    DeprecatedString pattern = "a+";
+    ByteString pattern = "a+";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED | REG_NOSUB), REG_NOERR);
@@ -120,7 +120,7 @@ TEST_CASE(simple_plus)
 
 TEST_CASE(simple_questionmark)
 {
-    DeprecatedString pattern = "da?d";
+    ByteString pattern = "da?d";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -137,7 +137,7 @@ TEST_CASE(simple_questionmark)
 
 TEST_CASE(simple_questionmark_matchall)
 {
-    DeprecatedString pattern = "da?d";
+    ByteString pattern = "da?d";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -170,12 +170,12 @@ TEST_CASE(simple_questionmark_matchall)
 
 TEST_CASE(character_class)
 {
-    DeprecatedString pattern = "[[:alpha:]]";
+    ByteString pattern = "[[:alpha:]]";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
 
-    DeprecatedString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
+    ByteString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
     EXPECT_EQ(regexec(&regex, haystack.characters(), num_matches, matches, 0), REG_NOMATCH);
     EXPECT_EQ(matches[0].rm_cnt, 0);
@@ -189,12 +189,12 @@ TEST_CASE(character_class)
 
 TEST_CASE(character_class2)
 {
-    DeprecatedString pattern = "[[:alpha:]]*=([[:digit:]]*)|\\[(.*)\\]";
+    ByteString pattern = "[[:alpha:]]*=([[:digit:]]*)|\\[(.*)\\]";
     regex_t regex;
     static constexpr int num_matches { 9 };
     regmatch_t matches[num_matches];
 
-    DeprecatedString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
+    ByteString haystack = "[Window]\nOpacity=255\nAudibleBeep=0\n";
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED | REG_NEWLINE), REG_NOERR);
     EXPECT_EQ(regexec(&regex, haystack.characters(), num_matches, matches, 0), REG_NOERR);
 
@@ -204,7 +204,7 @@ TEST_CASE(character_class2)
         fprintf(stderr, "Matches[%i].rm_so: %li, .rm_eo: %li .rm_cnt: %li: ", i, matches[i].rm_so, matches[i].rm_eo, matches[i].rm_cnt);
         fprintf(stderr, "haystack length: %lu\n", haystack.length());
         if (matches[i].rm_so != -1)
-            fprintf(stderr, "%s\n", haystack.substring_view(matches[i].rm_so, matches[i].rm_eo - matches[i].rm_so).to_deprecated_string().characters());
+            fprintf(stderr, "%s\n", haystack.substring_view(matches[i].rm_so, matches[i].rm_eo - matches[i].rm_so).to_byte_string().characters());
     }
 #endif
 
@@ -235,7 +235,7 @@ TEST_CASE(character_class2)
 
 TEST_CASE(escaped_char_questionmark)
 {
-    DeprecatedString pattern = "This\\.?And\\.?That";
+    ByteString pattern = "This\\.?And\\.?That";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -249,7 +249,7 @@ TEST_CASE(escaped_char_questionmark)
 
 TEST_CASE(char_qualifier_asterisk)
 {
-    DeprecatedString pattern = "regex*";
+    ByteString pattern = "regex*";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -263,7 +263,7 @@ TEST_CASE(char_qualifier_asterisk)
 
 TEST_CASE(char_utf8)
 {
-    DeprecatedString pattern = "😀";
+    ByteString pattern = "😀";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -277,7 +277,7 @@ TEST_CASE(char_utf8)
 
 TEST_CASE(parens)
 {
-    DeprecatedString pattern = "test(hello)test";
+    ByteString pattern = "test(hello)test";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -297,7 +297,7 @@ TEST_CASE(parens)
 
 TEST_CASE(parser_error_parens)
 {
-    DeprecatedString pattern = "test()test";
+    ByteString pattern = "test()test";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -310,7 +310,7 @@ TEST_CASE(parser_error_parens)
 
 TEST_CASE(parser_error_special_characters_used_at_wrong_place)
 {
-    DeprecatedString pattern;
+    ByteString pattern;
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -325,7 +325,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         // First in ere
         b.clear();
         b.append(ch);
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), error_code_to_check);
         EXPECT_EQ(regexec(&regex, "test", num_matches, matches, 0), error_code_to_check);
         regfree(&regex);
@@ -334,7 +334,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         b.clear();
         b.append("a|"sv);
         b.append(ch);
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), error_code_to_check);
         EXPECT_EQ(regexec(&regex, "test", num_matches, matches, 0), error_code_to_check);
         regfree(&regex);
@@ -343,7 +343,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         b.clear();
         b.append('^');
         b.append(ch);
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), error_code_to_check);
         EXPECT_EQ(regexec(&regex, "test", num_matches, matches, 0), error_code_to_check);
         regfree(&regex);
@@ -352,7 +352,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         b.clear();
         b.append('$');
         b.append(ch);
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), error_code_to_check);
         EXPECT_EQ(regexec(&regex, "test", num_matches, matches, 0), error_code_to_check);
         regfree(&regex);
@@ -362,7 +362,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
         b.append('(');
         b.append(ch);
         b.append(')');
-        pattern = b.to_deprecated_string();
+        pattern = b.to_byte_string();
         EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), error_code_to_check);
         EXPECT_EQ(regexec(&regex, "test", num_matches, matches, 0), error_code_to_check);
         regfree(&regex);
@@ -371,7 +371,7 @@ TEST_CASE(parser_error_special_characters_used_at_wrong_place)
 
 TEST_CASE(parser_error_vertical_line_used_at_wrong_place)
 {
-    DeprecatedString pattern;
+    ByteString pattern;
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -403,7 +403,7 @@ TEST_CASE(parser_error_vertical_line_used_at_wrong_place)
 
 TEST_CASE(parens_qualifier_questionmark)
 {
-    DeprecatedString pattern = "test(hello)?test";
+    ByteString pattern = "test(hello)?test";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -433,7 +433,7 @@ TEST_CASE(parens_qualifier_questionmark)
 
 TEST_CASE(parens_qualifier_asterisk)
 {
-    DeprecatedString pattern = "test(hello)*test";
+    ByteString pattern = "test(hello)*test";
     regex_t regex;
     static constexpr int num_matches { 6 };
     regmatch_t matches[num_matches];
@@ -479,7 +479,7 @@ TEST_CASE(parens_qualifier_asterisk)
 
 TEST_CASE(parens_qualifier_asterisk_2)
 {
-    DeprecatedString pattern = "test(.*)test";
+    ByteString pattern = "test(.*)test";
     regex_t regex;
     static constexpr int num_matches { 6 };
     regmatch_t matches[num_matches];
@@ -523,7 +523,7 @@ TEST_CASE(parens_qualifier_asterisk_2)
 
 TEST_CASE(mulit_parens_qualifier_too_less_result_values)
 {
-    DeprecatedString pattern = "test(a)?(b)?(c)?test";
+    ByteString pattern = "test(a)?(b)?(c)?test";
     regex_t regex;
     static constexpr int num_matches { 4 };
     regmatch_t matches[num_matches];
@@ -587,7 +587,7 @@ TEST_CASE(mulit_parens_qualifier_too_less_result_values)
 
 TEST_CASE(multi_parens_qualifier_questionmark)
 {
-    DeprecatedString pattern = "test(a)?(b)?(c)?test";
+    ByteString pattern = "test(a)?(b)?(c)?test";
     regex_t regex;
     static constexpr int num_matches { 8 };
     regmatch_t matches[num_matches];
@@ -651,7 +651,7 @@ TEST_CASE(multi_parens_qualifier_questionmark)
 
 TEST_CASE(simple_alternative)
 {
-    DeprecatedString pattern = "test|hello|friends";
+    ByteString pattern = "test|hello|friends";
     regex_t regex;
     static constexpr int num_matches { 1 };
     regmatch_t matches[num_matches];
@@ -678,7 +678,7 @@ TEST_CASE(simple_alternative)
 
 TEST_CASE(alternative_match_groups)
 {
-    DeprecatedString pattern = "test(a)?(b)?|hello ?(dear|my)? friends";
+    ByteString pattern = "test(a)?(b)?|hello ?(dear|my)? friends";
     regex_t regex;
     static constexpr int num_matches { 8 };
     regmatch_t matches[num_matches];
@@ -784,7 +784,7 @@ TEST_CASE(alternative_match_groups)
 
 TEST_CASE(parens_qualifier_exact)
 {
-    DeprecatedString pattern = "(hello){3}";
+    ByteString pattern = "(hello){3}";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -831,7 +831,7 @@ TEST_CASE(parens_qualifier_exact)
 
 TEST_CASE(parens_qualifier_minimum)
 {
-    DeprecatedString pattern = "(hello){3,}";
+    ByteString pattern = "(hello){3,}";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -889,7 +889,7 @@ TEST_CASE(parens_qualifier_minimum)
 
 TEST_CASE(parens_qualifier_maximum)
 {
-    DeprecatedString pattern = "(hello){2,3}";
+    ByteString pattern = "(hello){2,3}";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -946,7 +946,7 @@ TEST_CASE(parens_qualifier_maximum)
 
 TEST_CASE(char_qualifier_min_max)
 {
-    DeprecatedString pattern = "c{3,30}";
+    ByteString pattern = "c{3,30}";
     regex_t regex;
     static constexpr int num_matches { 5 };
     regmatch_t matches[num_matches];
@@ -966,7 +966,7 @@ TEST_CASE(char_qualifier_min_max)
 
 TEST_CASE(simple_bracket_chars)
 {
-    DeprecatedString pattern = "[abc]";
+    ByteString pattern = "[abc]";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -980,7 +980,7 @@ TEST_CASE(simple_bracket_chars)
 
 TEST_CASE(simple_bracket_chars_inverse)
 {
-    DeprecatedString pattern = "[^abc]";
+    ByteString pattern = "[^abc]";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -994,7 +994,7 @@ TEST_CASE(simple_bracket_chars_inverse)
 
 TEST_CASE(simple_bracket_chars_range)
 {
-    DeprecatedString pattern = "[a-d]";
+    ByteString pattern = "[a-d]";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -1008,7 +1008,7 @@ TEST_CASE(simple_bracket_chars_range)
 
 TEST_CASE(simple_bracket_chars_range_inverse)
 {
-    DeprecatedString pattern = "[^a-df-z]";
+    ByteString pattern = "[^a-df-z]";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -1024,7 +1024,7 @@ TEST_CASE(simple_bracket_chars_range_inverse)
 
 TEST_CASE(bracket_character_class_uuid)
 {
-    DeprecatedString pattern = "^([[:xdigit:]]{8})-([[:xdigit:]]{4})-([[:xdigit:]]{4})-([[:xdigit:]]{4})-([[:xdigit:]]{12})$";
+    ByteString pattern = "^([[:xdigit:]]{8})-([[:xdigit:]]{4})-([[:xdigit:]]{4})-([[:xdigit:]]{4})-([[:xdigit:]]{12})$";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -1036,7 +1036,7 @@ TEST_CASE(bracket_character_class_uuid)
 
 TEST_CASE(simple_bracket_character_class_inverse)
 {
-    DeprecatedString pattern = "[^[:digit:]]";
+    ByteString pattern = "[^[:digit:]]";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -1050,7 +1050,7 @@ TEST_CASE(simple_bracket_character_class_inverse)
 
 TEST_CASE(email_address)
 {
-    DeprecatedString pattern = "^[A-Z0-9a-z._%+-]{1,64}@(?:[A-Za-z0-9-]{1,63}\\.){1,125}[A-Za-z]{2,63}$";
+    ByteString pattern = "^[A-Z0-9a-z._%+-]{1,64}@(?:[A-Za-z0-9-]{1,63}\\.){1,125}[A-Za-z]{2,63}$";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_NOERR);
@@ -1062,7 +1062,7 @@ TEST_CASE(email_address)
 
 TEST_CASE(error_message)
 {
-    DeprecatedString pattern = "^[A-Z0-9[a-z._%+-]{1,64}@[A-Za-z0-9-]{1,63}\\.{1,125}[A-Za-z]{2,63}$";
+    ByteString pattern = "^[A-Z0-9[a-z._%+-]{1,64}@[A-Za-z0-9-]{1,63}\\.{1,125}[A-Za-z]{2,63}$";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED), REG_EBRACK);
@@ -1070,7 +1070,7 @@ TEST_CASE(error_message)
     char buf[1024];
     size_t buflen = 1024;
     auto len = regerror(0, &regex, buf, buflen);
-    DeprecatedString expected = "Error during parsing of regular expression:\n    ^[A-Z0-9[a-z._%+-]{1,64}@[A-Za-z0-9-]{1,63}\\.{1,125}[A-Za-z]{2,63}$\n             ^---- [ ] imbalance.";
+    ByteString expected = "Error during parsing of regular expression:\n    ^[A-Z0-9[a-z._%+-]{1,64}@[A-Za-z0-9-]{1,63}\\.{1,125}[A-Za-z]{2,63}$\n             ^---- [ ] imbalance.";
     for (size_t i = 0; i < len; ++i) {
         EXPECT_EQ(buf[i], expected[i]);
     }
@@ -1080,7 +1080,7 @@ TEST_CASE(error_message)
 
 TEST_CASE(simple_ignorecase)
 {
-    DeprecatedString pattern = "^hello friends";
+    ByteString pattern = "^hello friends";
     regex_t regex;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED | REG_NOSUB | REG_ICASE), REG_NOERR);
@@ -1098,8 +1098,8 @@ TEST_CASE(simple_ignorecase)
 
 TEST_CASE(simple_notbol_noteol)
 {
-    DeprecatedString pattern = "^hello friends$";
-    DeprecatedString pattern2 = "hello friends";
+    ByteString pattern = "^hello friends$";
+    ByteString pattern2 = "hello friends";
     regex_t regex, regex2;
 
     EXPECT_EQ(regcomp(&regex, pattern.characters(), REG_EXTENDED | REG_NOSUB | REG_ICASE), REG_NOERR);
diff --git a/Tests/LibSQL/TestSqlDatabase.cpp b/Tests/LibSQL/TestSqlDatabase.cpp
index 911e5c48390..1d5e66c1e83 100644
--- a/Tests/LibSQL/TestSqlDatabase.cpp
+++ b/Tests/LibSQL/TestSqlDatabase.cpp
@@ -46,7 +46,7 @@ static void insert_into_table(SQL::Database& db, int count)
         StringBuilder builder;
         builder.appendff("Test{}", ix);
 
-        row["TextColumn"] = builder.to_deprecated_string();
+        row["TextColumn"] = builder.to_byte_string();
         row["IntColumn"] = ix;
         TRY_OR_FAIL(db.insert(row));
     }
@@ -62,7 +62,7 @@ static void verify_table_contents(SQL::Database& db, int expected_count)
     for (auto& row : rows) {
         StringBuilder builder;
         builder.appendff("Test{}", row["IntColumn"].to_int<i32>().value());
-        EXPECT_EQ(row["TextColumn"].to_deprecated_string(), builder.to_deprecated_string());
+        EXPECT_EQ(row["TextColumn"].to_byte_string(), builder.to_byte_string());
         count++;
         sum += row["IntColumn"].to_int<i32>().value();
     }
diff --git a/Tests/LibSQL/TestSqlExpressionParser.cpp b/Tests/LibSQL/TestSqlExpressionParser.cpp
index 1dce2341840..39957487b70 100644
--- a/Tests/LibSQL/TestSqlExpressionParser.cpp
+++ b/Tests/LibSQL/TestSqlExpressionParser.cpp
@@ -7,7 +7,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/Result.h>
 #include <AK/StringBuilder.h>
@@ -31,7 +31,7 @@ public:
     }
 };
 
-using ParseResult = AK::Result<NonnullRefPtr<SQL::AST::Expression>, DeprecatedString>;
+using ParseResult = AK::Result<NonnullRefPtr<SQL::AST::Expression>, ByteString>;
 
 ParseResult parse(StringView sql)
 {
@@ -39,7 +39,7 @@ ParseResult parse(StringView sql)
     auto expression = parser.parse();
 
     if (parser.has_errors()) {
-        return parser.errors()[0].to_deprecated_string();
+        return parser.errors()[0].to_byte_string();
     }
 
     return expression;
@@ -225,14 +225,14 @@ TEST_CASE(binary_operator)
         StringBuilder builder;
         builder.append("1 "sv);
         builder.append(op.key);
-        EXPECT(parse(builder.to_deprecated_string()).is_error());
+        EXPECT(parse(builder.to_byte_string()).is_error());
 
         builder.clear();
 
         if (op.key != "+" && op.key != "-") { // "+1" and "-1" are fine (unary operator).
             builder.append(op.key);
             builder.append(" 1"sv);
-            EXPECT(parse(builder.to_deprecated_string()).is_error());
+            EXPECT(parse(builder.to_byte_string()).is_error());
         }
     }
 
@@ -251,7 +251,7 @@ TEST_CASE(binary_operator)
         builder.append("1 "sv);
         builder.append(op.key);
         builder.append(" 1"sv);
-        validate(builder.to_deprecated_string(), op.value);
+        validate(builder.to_byte_string(), op.value);
     }
 }
 
@@ -438,12 +438,12 @@ TEST_CASE(match_expression)
         StringBuilder builder;
         builder.append("1 "sv);
         builder.append(op.key);
-        EXPECT(parse(builder.to_deprecated_string()).is_error());
+        EXPECT(parse(builder.to_byte_string()).is_error());
 
         builder.clear();
         builder.append(op.key);
         builder.append(" 1"sv);
-        EXPECT(parse(builder.to_deprecated_string()).is_error());
+        EXPECT(parse(builder.to_byte_string()).is_error());
     }
 
     auto validate = [](StringView sql, SQL::AST::MatchOperator expected_operator, bool expected_invert_expression, bool expect_escape) {
@@ -463,19 +463,19 @@ TEST_CASE(match_expression)
         builder.append("1 "sv);
         builder.append(op.key);
         builder.append(" 1"sv);
-        validate(builder.to_deprecated_string(), op.value, false, false);
+        validate(builder.to_byte_string(), op.value, false, false);
 
         builder.clear();
         builder.append("1 NOT "sv);
         builder.append(op.key);
         builder.append(" 1"sv);
-        validate(builder.to_deprecated_string(), op.value, true, false);
+        validate(builder.to_byte_string(), op.value, true, false);
 
         builder.clear();
         builder.append("1 NOT "sv);
         builder.append(op.key);
         builder.append(" 1 ESCAPE '+'"sv);
-        validate(builder.to_deprecated_string(), op.value, true, true);
+        validate(builder.to_byte_string(), op.value, true, true);
     }
 }
 
@@ -598,7 +598,7 @@ TEST_CASE(in_selection_expression)
 
 TEST_CASE(expression_tree_depth_limit)
 {
-    auto too_deep_expression = DeprecatedString::formatted("{:+^{}}1", "", SQL::AST::Limits::maximum_expression_tree_depth);
+    auto too_deep_expression = ByteString::formatted("{:+^{}}1", "", SQL::AST::Limits::maximum_expression_tree_depth);
     EXPECT(!parse(too_deep_expression.substring_view(1)).is_error());
     EXPECT(parse(too_deep_expression).is_error());
 }
diff --git a/Tests/LibSQL/TestSqlStatementExecution.cpp b/Tests/LibSQL/TestSqlStatementExecution.cpp
index 930823cc1a2..e4c21138f28 100644
--- a/Tests/LibSQL/TestSqlStatementExecution.cpp
+++ b/Tests/LibSQL/TestSqlStatementExecution.cpp
@@ -21,17 +21,17 @@ namespace {
 
 constexpr char const* db_name = "/tmp/test.db";
 
-SQL::ResultOr<SQL::ResultSet> try_execute(NonnullRefPtr<SQL::Database> database, DeprecatedString const& sql, Vector<SQL::Value> placeholder_values = {})
+SQL::ResultOr<SQL::ResultSet> try_execute(NonnullRefPtr<SQL::Database> database, ByteString const& sql, Vector<SQL::Value> placeholder_values = {})
 {
     auto parser = SQL::AST::Parser(SQL::AST::Lexer(sql));
     auto statement = parser.next_statement();
     EXPECT(!parser.has_errors());
     if (parser.has_errors())
-        outln("{}", parser.errors()[0].to_deprecated_string());
+        outln("{}", parser.errors()[0].to_byte_string());
     return statement->execute(move(database), placeholder_values);
 }
 
-SQL::ResultSet execute(NonnullRefPtr<SQL::Database> database, DeprecatedString const& sql, Vector<SQL::Value> placeholder_values = {})
+SQL::ResultSet execute(NonnullRefPtr<SQL::Database> database, ByteString const& sql, Vector<SQL::Value> placeholder_values = {})
 {
     auto result = try_execute(move(database), sql, move(placeholder_values));
     if (result.is_error()) {
@@ -101,7 +101,7 @@ TEST_CASE(insert_into_table)
     int count = 0;
     auto rows = TRY_OR_FAIL(database->select_all(*table));
     for (auto& row : rows) {
-        EXPECT_EQ(row["TEXTCOLUMN"].to_deprecated_string(), "Test");
+        EXPECT_EQ(row["TEXTCOLUMN"].to_byte_string(), "Test");
         EXPECT_EQ(row["INTCOLUMN"].to_int<i32>(), 42);
         count++;
     }
@@ -380,8 +380,8 @@ TEST_CASE(select_inner_join)
     EXPECT_EQ(result.size(), 1u);
     EXPECT_EQ(result[0].row.size(), 3u);
     EXPECT_EQ(result[0].row[0].to_int<i32>(), 42);
-    EXPECT_EQ(result[0].row[1].to_deprecated_string(), "Test_1");
-    EXPECT_EQ(result[0].row[2].to_deprecated_string(), "Test_12");
+    EXPECT_EQ(result[0].row[1].to_byte_string(), "Test_1");
+    EXPECT_EQ(result[0].row[2].to_byte_string(), "Test_12");
 }
 
 TEST_CASE(select_with_like)
@@ -467,11 +467,11 @@ TEST_CASE(select_with_order)
 
     result = execute(database, "SELECT TextColumn, IntColumn FROM TestSchema.TestTable ORDER BY TextColumn;");
     EXPECT_EQ(result.size(), 5u);
-    EXPECT_EQ(result[0].row[0].to_deprecated_string(), "Test_1");
-    EXPECT_EQ(result[1].row[0].to_deprecated_string(), "Test_2");
-    EXPECT_EQ(result[2].row[0].to_deprecated_string(), "Test_3");
-    EXPECT_EQ(result[3].row[0].to_deprecated_string(), "Test_4");
-    EXPECT_EQ(result[4].row[0].to_deprecated_string(), "Test_5");
+    EXPECT_EQ(result[0].row[0].to_byte_string(), "Test_1");
+    EXPECT_EQ(result[1].row[0].to_byte_string(), "Test_2");
+    EXPECT_EQ(result[2].row[0].to_byte_string(), "Test_3");
+    EXPECT_EQ(result[3].row[0].to_byte_string(), "Test_4");
+    EXPECT_EQ(result[4].row[0].to_byte_string(), "Test_5");
 }
 
 TEST_CASE(select_with_regexp)
@@ -542,15 +542,15 @@ TEST_CASE(select_with_order_two_columns)
 
     result = execute(database, "SELECT TextColumn, IntColumn FROM TestSchema.TestTable ORDER BY TextColumn, IntColumn;");
     EXPECT_EQ(result.size(), 5u);
-    EXPECT_EQ(result[0].row[0].to_deprecated_string(), "Test_1");
+    EXPECT_EQ(result[0].row[0].to_byte_string(), "Test_1");
     EXPECT_EQ(result[0].row[1].to_int<i32>(), 47);
-    EXPECT_EQ(result[1].row[0].to_deprecated_string(), "Test_2");
+    EXPECT_EQ(result[1].row[0].to_byte_string(), "Test_2");
     EXPECT_EQ(result[1].row[1].to_int<i32>(), 40);
-    EXPECT_EQ(result[2].row[0].to_deprecated_string(), "Test_2");
+    EXPECT_EQ(result[2].row[0].to_byte_string(), "Test_2");
     EXPECT_EQ(result[2].row[1].to_int<i32>(), 42);
-    EXPECT_EQ(result[3].row[0].to_deprecated_string(), "Test_4");
+    EXPECT_EQ(result[3].row[0].to_byte_string(), "Test_4");
     EXPECT_EQ(result[3].row[1].to_int<i32>(), 41);
-    EXPECT_EQ(result[4].row[0].to_deprecated_string(), "Test_5");
+    EXPECT_EQ(result[4].row[0].to_byte_string(), "Test_5");
     EXPECT_EQ(result[4].row[1].to_int<i32>(), 44);
 }
 
@@ -571,11 +571,11 @@ TEST_CASE(select_with_order_by_column_not_in_result)
 
     result = execute(database, "SELECT TextColumn FROM TestSchema.TestTable ORDER BY IntColumn;");
     EXPECT_EQ(result.size(), 5u);
-    EXPECT_EQ(result[0].row[0].to_deprecated_string(), "Test_3");
-    EXPECT_EQ(result[1].row[0].to_deprecated_string(), "Test_4");
-    EXPECT_EQ(result[2].row[0].to_deprecated_string(), "Test_2");
-    EXPECT_EQ(result[3].row[0].to_deprecated_string(), "Test_5");
-    EXPECT_EQ(result[4].row[0].to_deprecated_string(), "Test_1");
+    EXPECT_EQ(result[0].row[0].to_byte_string(), "Test_3");
+    EXPECT_EQ(result[1].row[0].to_byte_string(), "Test_4");
+    EXPECT_EQ(result[2].row[0].to_byte_string(), "Test_2");
+    EXPECT_EQ(result[3].row[0].to_byte_string(), "Test_5");
+    EXPECT_EQ(result[4].row[0].to_byte_string(), "Test_1");
 }
 
 TEST_CASE(select_with_limit)
@@ -586,7 +586,7 @@ TEST_CASE(select_with_limit)
     create_table(database);
     for (auto count = 0; count < 100; count++) {
         auto result = execute(database,
-            DeprecatedString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
+            ByteString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
         EXPECT(result.size() == 1);
     }
     auto result = execute(database, "SELECT TextColumn, IntColumn FROM TestSchema.TestTable LIMIT 10;");
@@ -602,7 +602,7 @@ TEST_CASE(select_with_limit_and_offset)
     create_table(database);
     for (auto count = 0; count < 100; count++) {
         auto result = execute(database,
-            DeprecatedString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
+            ByteString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
         EXPECT(result.size() == 1);
     }
     auto result = execute(database, "SELECT TextColumn, IntColumn FROM TestSchema.TestTable LIMIT 10 OFFSET 10;");
@@ -617,7 +617,7 @@ TEST_CASE(select_with_order_limit_and_offset)
     create_table(database);
     for (auto count = 0; count < 100; count++) {
         auto result = execute(database,
-            DeprecatedString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
+            ByteString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
         EXPECT(result.size() == 1);
     }
     auto result = execute(database, "SELECT TextColumn, IntColumn FROM TestSchema.TestTable ORDER BY IntColumn LIMIT 10 OFFSET 10;");
@@ -642,7 +642,7 @@ TEST_CASE(select_with_limit_out_of_bounds)
     create_table(database);
     for (auto count = 0; count < 100; count++) {
         auto result = execute(database,
-            DeprecatedString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
+            ByteString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
         EXPECT(result.size() == 1);
     }
     auto result = execute(database, "SELECT TextColumn, IntColumn FROM TestSchema.TestTable LIMIT 500;");
@@ -657,7 +657,7 @@ TEST_CASE(select_with_offset_out_of_bounds)
     create_table(database);
     for (auto count = 0; count < 100; count++) {
         auto result = execute(database,
-            DeprecatedString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
+            ByteString::formatted("INSERT INTO TestSchema.TestTable ( TextColumn, IntColumn ) VALUES ( 'Test_{}', {} );", count, count));
         EXPECT(result.size() == 1);
     }
     auto result = execute(database, "SELECT TextColumn, IntColumn FROM TestSchema.TestTable LIMIT 10 OFFSET 200;");
@@ -673,11 +673,11 @@ TEST_CASE(describe_table)
     auto result = execute(database, "DESCRIBE TABLE TestSchema.TestTable;");
     EXPECT_EQ(result.size(), 2u);
 
-    EXPECT_EQ(result[0].row[0].to_deprecated_string(), "TEXTCOLUMN");
-    EXPECT_EQ(result[0].row[1].to_deprecated_string(), "text");
+    EXPECT_EQ(result[0].row[0].to_byte_string(), "TEXTCOLUMN");
+    EXPECT_EQ(result[0].row[1].to_byte_string(), "text");
 
-    EXPECT_EQ(result[1].row[0].to_deprecated_string(), "INTCOLUMN");
-    EXPECT_EQ(result[1].row[1].to_deprecated_string(), "int");
+    EXPECT_EQ(result[1].row[0].to_byte_string(), "INTCOLUMN");
+    EXPECT_EQ(result[1].row[1].to_byte_string(), "int");
 }
 
 TEST_CASE(binary_operator_execution)
@@ -688,7 +688,7 @@ TEST_CASE(binary_operator_execution)
     create_table(database);
 
     for (auto count = 0; count < 10; ++count) {
-        auto result = execute(database, DeprecatedString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
+        auto result = execute(database, ByteString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
         EXPECT_EQ(result.size(), 1u);
     }
 
@@ -762,7 +762,7 @@ TEST_CASE(binary_operator_failure)
     create_table(database);
 
     for (auto count = 0; count < 10; ++count) {
-        auto result = execute(database, DeprecatedString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
+        auto result = execute(database, ByteString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
         EXPECT_EQ(result.size(), 1u);
     }
 
@@ -772,7 +772,7 @@ TEST_CASE(binary_operator_failure)
         auto error = result.release_error();
         EXPECT_EQ(error.error(), SQL::SQLErrorCode::NumericOperatorTypeMismatch);
 
-        auto message = DeprecatedString::formatted("NumericOperatorTypeMismatch: Cannot apply '{}' operator to non-numeric operands", op);
+        auto message = ByteString::formatted("NumericOperatorTypeMismatch: Cannot apply '{}' operator to non-numeric operands", op);
         EXPECT_EQ(error.error_string(), message);
     };
 
@@ -832,7 +832,7 @@ TEST_CASE(delete_single_row)
 
         create_table(database);
         for (auto count = 0; count < 10; ++count) {
-            auto result = execute(database, DeprecatedString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
+            auto result = execute(database, ByteString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
             EXPECT_EQ(result.size(), 1u);
         }
 
@@ -876,7 +876,7 @@ TEST_CASE(delete_multiple_rows)
 
         create_table(database);
         for (auto count = 0; count < 10; ++count) {
-            auto result = execute(database, DeprecatedString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
+            auto result = execute(database, ByteString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
             EXPECT_EQ(result.size(), 1u);
         }
 
@@ -916,7 +916,7 @@ TEST_CASE(delete_all_rows)
 
         create_table(database);
         for (auto count = 0; count < 10; ++count) {
-            auto result = execute(database, DeprecatedString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
+            auto result = execute(database, ByteString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
             EXPECT_EQ(result.size(), 1u);
         }
 
@@ -950,7 +950,7 @@ TEST_CASE(update_single_row)
 
         create_table(database);
         for (auto count = 0; count < 10; ++count) {
-            auto result = execute(database, DeprecatedString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
+            auto result = execute(database, ByteString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
             EXPECT_EQ(result.size(), 1u);
         }
 
@@ -995,7 +995,7 @@ TEST_CASE(update_multiple_rows)
 
         create_table(database);
         for (auto count = 0; count < 10; ++count) {
-            auto result = execute(database, DeprecatedString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
+            auto result = execute(database, ByteString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
             EXPECT_EQ(result.size(), 1u);
         }
 
@@ -1036,7 +1036,7 @@ TEST_CASE(update_all_rows)
 
         create_table(database);
         for (auto count = 0; count < 10; ++count) {
-            auto result = execute(database, DeprecatedString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
+            auto result = execute(database, ByteString::formatted("INSERT INTO TestSchema.TestTable VALUES ( 'T{}', {} );", count, count));
             EXPECT_EQ(result.size(), 1u);
         }
 
diff --git a/Tests/LibSQL/TestSqlStatementParser.cpp b/Tests/LibSQL/TestSqlStatementParser.cpp
index 81de1868cfb..9092c7f4c52 100644
--- a/Tests/LibSQL/TestSqlStatementParser.cpp
+++ b/Tests/LibSQL/TestSqlStatementParser.cpp
@@ -8,7 +8,7 @@
 
 #include <LibTest/TestCase.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <AK/Result.h>
 #include <AK/StringView.h>
@@ -19,7 +19,7 @@
 
 namespace {
 
-using ParseResult = AK::Result<NonnullRefPtr<SQL::AST::Statement>, DeprecatedString>;
+using ParseResult = AK::Result<NonnullRefPtr<SQL::AST::Statement>, ByteString>;
 
 ParseResult parse(StringView sql)
 {
@@ -27,7 +27,7 @@ ParseResult parse(StringView sql)
     auto statement = parser.next_statement();
 
     if (parser.has_errors()) {
-        return parser.errors()[0].to_deprecated_string();
+        return parser.errors()[0].to_byte_string();
     }
 
     return statement;
@@ -393,7 +393,7 @@ TEST_CASE(update)
     EXPECT(parse("UPDATE OR table_name SET column_name=4;"sv).is_error());
     EXPECT(parse("UPDATE OR foo table_name SET column_name=4;"sv).is_error());
 
-    auto validate = [](StringView sql, SQL::AST::ConflictResolution expected_conflict_resolution, StringView expected_schema, StringView expected_table, StringView expected_alias, Vector<Vector<DeprecatedString>> expected_update_columns, bool expect_where_clause, bool expect_returning_clause, Vector<StringView> expected_returned_column_aliases) {
+    auto validate = [](StringView sql, SQL::AST::ConflictResolution expected_conflict_resolution, StringView expected_schema, StringView expected_table, StringView expected_alias, Vector<Vector<ByteString>> expected_update_columns, bool expect_where_clause, bool expect_returning_clause, Vector<StringView> expected_returned_column_aliases) {
         auto statement = TRY_OR_FAIL(parse(sql));
         EXPECT(is<SQL::AST::Update>(*statement));
 
@@ -437,7 +437,7 @@ TEST_CASE(update)
         }
     };
 
-    Vector<Vector<DeprecatedString>> update_columns { { "COLUMN_NAME" } };
+    Vector<Vector<ByteString>> update_columns { { "COLUMN_NAME" } };
     validate("UPDATE OR ABORT table_name SET column_name=1;"sv, SQL::AST::ConflictResolution::Abort, {}, "TABLE_NAME"sv, {}, update_columns, false, false, {});
     validate("UPDATE OR FAIL table_name SET column_name=1;"sv, SQL::AST::ConflictResolution::Fail, {}, "TABLE_NAME"sv, {}, update_columns, false, false, {});
     validate("UPDATE OR IGNORE table_name SET column_name=1;"sv, SQL::AST::ConflictResolution::Ignore, {}, "TABLE_NAME"sv, {}, update_columns, false, false, {});
@@ -578,7 +578,7 @@ TEST_CASE(select)
     };
 
     struct Ordering {
-        DeprecatedString collation_name;
+        ByteString collation_name;
         SQL::Order order;
         SQL::Nulls nulls;
     };
@@ -752,16 +752,16 @@ TEST_CASE(common_table_expression)
 
 TEST_CASE(nested_subquery_limit)
 {
-    auto subquery = DeprecatedString::formatted("{:(^{}}table_name{:)^{}}", "", SQL::AST::Limits::maximum_subquery_depth - 1, "", SQL::AST::Limits::maximum_subquery_depth - 1);
-    EXPECT(!parse(DeprecatedString::formatted("SELECT * FROM {};"sv, subquery)).is_error());
-    EXPECT(parse(DeprecatedString::formatted("SELECT * FROM ({});"sv, subquery)).is_error());
+    auto subquery = ByteString::formatted("{:(^{}}table_name{:)^{}}", "", SQL::AST::Limits::maximum_subquery_depth - 1, "", SQL::AST::Limits::maximum_subquery_depth - 1);
+    EXPECT(!parse(ByteString::formatted("SELECT * FROM {};"sv, subquery)).is_error());
+    EXPECT(parse(ByteString::formatted("SELECT * FROM ({});"sv, subquery)).is_error());
 }
 
 TEST_CASE(bound_parameter_limit)
 {
-    auto subquery = DeprecatedString::repeated("?, "sv, SQL::AST::Limits::maximum_bound_parameters);
-    EXPECT(!parse(DeprecatedString::formatted("INSERT INTO table_name VALUES ({}42);"sv, subquery)).is_error());
-    EXPECT(parse(DeprecatedString::formatted("INSERT INTO table_name VALUES ({}?);"sv, subquery)).is_error());
+    auto subquery = ByteString::repeated("?, "sv, SQL::AST::Limits::maximum_bound_parameters);
+    EXPECT(!parse(ByteString::formatted("INSERT INTO table_name VALUES ({}42);"sv, subquery)).is_error());
+    EXPECT(parse(ByteString::formatted("INSERT INTO table_name VALUES ({}?);"sv, subquery)).is_error());
 }
 
 TEST_CASE(describe_table)
diff --git a/Tests/LibSQL/TestSqlValueAndTuple.cpp b/Tests/LibSQL/TestSqlValueAndTuple.cpp
index cacdfe61cb3..65263531339 100644
--- a/Tests/LibSQL/TestSqlValueAndTuple.cpp
+++ b/Tests/LibSQL/TestSqlValueAndTuple.cpp
@@ -17,7 +17,7 @@ TEST_CASE(null_value)
 {
     SQL::Value v(SQL::SQLType::Null);
     EXPECT_EQ(v.type(), SQL::SQLType::Null);
-    EXPECT_EQ(v.to_deprecated_string(), "(null)"sv);
+    EXPECT_EQ(v.to_byte_string(), "(null)"sv);
     EXPECT(!v.to_bool().has_value());
     EXPECT(!v.to_int<i32>().has_value());
     EXPECT(!v.to_int<u32>().has_value());
@@ -44,25 +44,25 @@ TEST_CASE(text_value)
 
         v = "Test"sv;
         EXPECT_EQ(v.type(), SQL::SQLType::Text);
-        EXPECT_EQ(v.to_deprecated_string(), "Test"sv);
+        EXPECT_EQ(v.to_byte_string(), "Test"sv);
     }
     {
-        SQL::Value v(DeprecatedString("String Test"sv));
+        SQL::Value v(ByteString("String Test"sv));
         EXPECT_EQ(v.type(), SQL::SQLType::Text);
-        EXPECT_EQ(v.to_deprecated_string(), "String Test"sv);
+        EXPECT_EQ(v.to_byte_string(), "String Test"sv);
 
-        v = DeprecatedString("String Test 2"sv);
+        v = ByteString("String Test 2"sv);
         EXPECT_EQ(v.type(), SQL::SQLType::Text);
-        EXPECT_EQ(v.to_deprecated_string(), "String Test 2"sv);
+        EXPECT_EQ(v.to_byte_string(), "String Test 2"sv);
     }
     {
         SQL::Value v("const char * Test");
         EXPECT_EQ(v.type(), SQL::SQLType::Text);
-        EXPECT_EQ(v.to_deprecated_string(), "const char * Test"sv);
+        EXPECT_EQ(v.to_byte_string(), "const char * Test"sv);
 
         v = "const char * Test 2";
         EXPECT_EQ(v.type(), SQL::SQLType::Text);
-        EXPECT_EQ(v.to_deprecated_string(), "const char * Test 2"sv);
+        EXPECT_EQ(v.to_byte_string(), "const char * Test 2"sv);
     }
 }
 
@@ -149,7 +149,7 @@ TEST_CASE(integer_value)
 
         EXPECT(v.to_int<i32>().has_value());
         EXPECT_EQ(v.to_int<i32>().value(), 42);
-        EXPECT_EQ(v.to_deprecated_string(), "42"sv);
+        EXPECT_EQ(v.to_byte_string(), "42"sv);
 
         EXPECT(v.to_double().has_value());
         EXPECT((v.to_double().value() - 42.0) < NumericLimits<double>().epsilon());
@@ -261,7 +261,7 @@ TEST_CASE(float_value)
 
         EXPECT(v.to_int<i32>().has_value());
         EXPECT_EQ(v.to_int<i32>().value(), 3);
-        EXPECT_EQ(v.to_deprecated_string(), "3.14");
+        EXPECT_EQ(v.to_byte_string(), "3.14");
 
         EXPECT(v.to_bool().has_value());
         EXPECT(v.to_bool().value());
@@ -274,7 +274,7 @@ TEST_CASE(float_value)
 
         EXPECT(v.to_int<i32>().has_value());
         EXPECT_EQ(v.to_int<i32>().value(), 0);
-        EXPECT_EQ(v.to_deprecated_string(), "0"sv);
+        EXPECT_EQ(v.to_byte_string(), "0"sv);
 
         EXPECT(v.to_bool().has_value());
         EXPECT(!v.to_bool().value());
@@ -420,7 +420,7 @@ TEST_CASE(bool_value)
 
         EXPECT(v.to_int<i32>().has_value());
         EXPECT_EQ(v.to_int<i32>().value(), 1);
-        EXPECT_EQ(v.to_deprecated_string(), "true"sv);
+        EXPECT_EQ(v.to_byte_string(), "true"sv);
 
         EXPECT(v.to_double().has_value());
         EXPECT((v.to_double().value() - 1.0) < NumericLimits<double>().epsilon());
@@ -434,7 +434,7 @@ TEST_CASE(bool_value)
 
         EXPECT(v.to_int<i32>().has_value());
         EXPECT_EQ(v.to_int<i32>().value(), 0);
-        EXPECT_EQ(v.to_deprecated_string(), "false"sv);
+        EXPECT_EQ(v.to_byte_string(), "false"sv);
 
         EXPECT(v.to_double().has_value());
         EXPECT(v.to_double().value() < NumericLimits<double>().epsilon());
@@ -448,7 +448,7 @@ TEST_CASE(bool_value)
 
         EXPECT(v.to_int<i32>().has_value());
         EXPECT_EQ(v.to_int<i32>().value(), 1);
-        EXPECT_EQ(v.to_deprecated_string(), "true"sv);
+        EXPECT_EQ(v.to_byte_string(), "true"sv);
 
         EXPECT(v.to_double().has_value());
         EXPECT((v.to_double().value() - 1.0) < NumericLimits<double>().epsilon());
diff --git a/Tests/LibTLS/TestTLSHandshake.cpp b/Tests/LibTLS/TestTLSHandshake.cpp
index b4feabdb17b..4cdc6bcd191 100644
--- a/Tests/LibTLS/TestTLSHandshake.cpp
+++ b/Tests/LibTLS/TestTLSHandshake.cpp
@@ -24,14 +24,14 @@ static ByteBuffer operator""_b(char const* string, size_t length)
 }
 
 ErrorOr<Vector<Certificate>> load_certificates();
-DeprecatedString locate_ca_certs_file();
+ByteString locate_ca_certs_file();
 
-DeprecatedString locate_ca_certs_file()
+ByteString locate_ca_certs_file()
 {
     if (FileSystem::exists(ca_certs_file)) {
         return ca_certs_file;
     }
-    auto on_target_path = DeprecatedString("/etc/cacert.pem");
+    auto on_target_path = ByteString("/etc/cacert.pem");
     if (FileSystem::exists(on_target_path)) {
         return on_target_path;
     }
diff --git a/Tests/LibWasm/test-wasm.cpp b/Tests/LibWasm/test-wasm.cpp
index b1e5d17cf66..f9ee31c46e0 100644
--- a/Tests/LibWasm/test-wasm.cpp
+++ b/Tests/LibWasm/test-wasm.cpp
@@ -21,7 +21,7 @@ TESTJS_GLOBAL_FUNCTION(read_binary_wasm_file, readBinaryWasmFile)
         return StringView { error_string, strlen(error_string) };
     };
 
-    auto filename = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto filename = TRY(vm.argument(0).to_byte_string(vm));
     auto file = Core::File::open(filename, Core::File::OpenMode::Read);
     if (file.is_error())
         return vm.throw_completion<JS::TypeError>(error_code_to_string(file.error().code()));
@@ -114,7 +114,7 @@ TESTJS_GLOBAL_FUNCTION(parse_webassembly_module, parseWebAssemblyModule)
     FixedMemoryStream stream { array.data() };
     auto result = Wasm::Module::parse(stream);
     if (result.is_error())
-        return vm.throw_completion<JS::SyntaxError>(Wasm::parse_error_to_deprecated_string(result.error()));
+        return vm.throw_completion<JS::SyntaxError>(Wasm::parse_error_to_byte_string(result.error()));
 
     HashMap<Wasm::Linker::Name, Wasm::ExternValue> imports;
     auto import_value = vm.argument(1);
@@ -157,7 +157,7 @@ void WebAssemblyModule::initialize(JS::Realm& realm)
 
 JS_DEFINE_NATIVE_FUNCTION(WebAssemblyModule::get_export)
 {
-    auto name = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto name = TRY(vm.argument(0).to_byte_string(vm));
     auto this_value = vm.this_value();
     auto object = TRY(this_value.to_object(vm));
     if (!is<WebAssemblyModule>(*object))
diff --git a/Tests/LibWeb/TestHTMLTokenizer.cpp b/Tests/LibWeb/TestHTMLTokenizer.cpp
index b4ac3b0fbfc..1bb25f3336d 100644
--- a/Tests/LibWeb/TestHTMLTokenizer.cpp
+++ b/Tests/LibWeb/TestHTMLTokenizer.cpp
@@ -234,7 +234,7 @@ TEST_CASE(regression)
     auto file_size = MUST(file->size());
     auto content = MUST(ByteBuffer::create_uninitialized(file_size));
     MUST(file->read_until_filled(content.bytes()));
-    DeprecatedString file_contents { content.bytes() };
+    ByteString file_contents { content.bytes() };
     auto tokens = run_tokenizer(file_contents);
     u32 hash = hash_tokens(tokens);
     EXPECT_EQ(hash, 3657343287u);
diff --git a/Tests/Spreadsheet/test-spreadsheet.cpp b/Tests/Spreadsheet/test-spreadsheet.cpp
index 541728182a0..3b366beeddf 100644
--- a/Tests/Spreadsheet/test-spreadsheet.cpp
+++ b/Tests/Spreadsheet/test-spreadsheet.cpp
@@ -15,13 +15,13 @@ static constexpr auto s_spreadsheet_runtime_path = "/res/js/Spreadsheet/runtime.
 static constexpr auto s_spreadsheet_runtime_path = "../../../../Base/res/js/Spreadsheet/runtime.js"sv;
 #endif
 
-TESTJS_RUN_FILE_FUNCTION(DeprecatedString const&, JS::Realm& realm, JS::ExecutionContext& global_execution_context)
+TESTJS_RUN_FILE_FUNCTION(ByteString const&, JS::Realm& realm, JS::ExecutionContext& global_execution_context)
 {
     auto run_file = [&](StringView name) {
         auto result = Test::JS::parse_script(name, realm);
         if (result.is_error()) {
             warnln("Unable to parse {}", name);
-            warnln("{}", result.error().error.to_deprecated_string());
+            warnln("{}", result.error().error.to_byte_string());
             warnln("{}", result.error().hint);
             Test::cleanup_and_exit();
         }
diff --git a/Tests/Utilities/TestSed.cpp b/Tests/Utilities/TestSed.cpp
index be6fc1089a7..c6b111251ad 100644
--- a/Tests/Utilities/TestSed.cpp
+++ b/Tests/Utilities/TestSed.cpp
@@ -20,7 +20,7 @@ static void run_sed(Vector<char const*>&& arguments, StringView standard_input,
     auto [stdout, stderr] = MUST(sed->read_all());
     auto status = MUST(sed->status());
     if (status != Core::Command::ProcessResult::DoneWithZeroExitCode) {
-        FAIL(DeprecatedString::formatted("sed didn't exit cleanly: status: {}, stdout:{}, stderr: {}", static_cast<int>(status), StringView { stdout.bytes() }, StringView { stderr.bytes() }));
+        FAIL(ByteString::formatted("sed didn't exit cleanly: status: {}, stdout:{}, stderr: {}", static_cast<int>(status), StringView { stdout.bytes() }, StringView { stderr.bytes() }));
     }
     EXPECT_EQ(StringView { expected_stdout.bytes() }, StringView { stdout.bytes() });
 }
diff --git a/Userland/Applets/Audio/main.cpp b/Userland/Applets/Audio/main.cpp
index 2e0019e6c37..6a7b295f756 100644
--- a/Userland/Applets/Audio/main.cpp
+++ b/Userland/Applets/Audio/main.cpp
@@ -170,7 +170,7 @@ private:
         painter.blit({}, audio_bitmap, audio_bitmap.rect());
 
         if (show_percent()) {
-            auto volume_text = m_audio_muted ? "mute" : DeprecatedString::formatted("{}%", m_audio_volume);
+            auto volume_text = m_audio_muted ? "mute" : ByteString::formatted("{}%", m_audio_volume);
             painter.draw_text(Gfx::IntRect { 16, 3, 24, 16 }, volume_text, Gfx::FontDatabase::default_fixed_width_font(), Gfx::TextAlignment::TopLeft, palette().window_text());
         }
     }
diff --git a/Userland/Applets/ClipboardHistory/ClipboardHistoryModel.cpp b/Userland/Applets/ClipboardHistory/ClipboardHistoryModel.cpp
index 6bd26f3d5f0..6dba68357f9 100644
--- a/Userland/Applets/ClipboardHistory/ClipboardHistoryModel.cpp
+++ b/Userland/Applets/ClipboardHistory/ClipboardHistoryModel.cpp
@@ -39,7 +39,7 @@ ErrorOr<String> ClipboardHistoryModel::column_name(int column) const
     }
 }
 
-static StringView bpp_for_format_resilient(DeprecatedString format)
+static StringView bpp_for_format_resilient(ByteString format)
 {
     unsigned format_uint = format.to_uint().value_or(static_cast<unsigned>(Gfx::BitmapFormat::Invalid));
     // Cannot use Gfx::Bitmap::bpp_for_format here, as we have to accept invalid enum values.
@@ -64,7 +64,7 @@ GUI::Variant ClipboardHistoryModel::data(const GUI::ModelIndex& index, GUI::Mode
     switch (index.column()) {
     case Column::Data:
         if (data_and_type.mime_type.starts_with("text/"sv))
-            return DeprecatedString::copy(data_and_type.data);
+            return ByteString::copy(data_and_type.data);
         if (data_and_type.mime_type == "image/x-serenityos") {
             StringBuilder builder;
             builder.append('[');
@@ -75,7 +75,7 @@ GUI::Variant ClipboardHistoryModel::data(const GUI::ModelIndex& index, GUI::Mode
             builder.append(bpp_for_format_resilient(data_and_type.metadata.get("format").value_or("0")));
             builder.append(']');
             builder.append(" bitmap"sv);
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         }
         if (data_and_type.mime_type.starts_with("glyph/"sv)) {
             StringBuilder builder;
@@ -90,7 +90,7 @@ GUI::Variant ClipboardHistoryModel::data(const GUI::ModelIndex& index, GUI::Mode
                 builder.append_code_point(start);
                 builder.appendff(") [{}x{}]", width, height);
             }
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         }
         return "<...>";
     case Column::Type:
@@ -98,13 +98,13 @@ GUI::Variant ClipboardHistoryModel::data(const GUI::ModelIndex& index, GUI::Mode
     case Column::Size:
         return AK::human_readable_size(data_and_type.data.size());
     case Column::Time:
-        return time.to_deprecated_string();
+        return time.to_byte_string();
     default:
         VERIFY_NOT_REACHED();
     }
 }
 
-void ClipboardHistoryModel::clipboard_content_did_change(DeprecatedString const&)
+void ClipboardHistoryModel::clipboard_content_did_change(ByteString const&)
 {
     auto data_and_type = GUI::Clipboard::the().fetch_data_and_type();
     if (!(data_and_type.data.is_empty() && data_and_type.mime_type.is_empty() && data_and_type.metadata.is_empty()))
@@ -184,7 +184,7 @@ ErrorOr<JsonObject> ClipboardHistoryModel::ClipboardItem::to_json() const
     return object;
 }
 
-ErrorOr<void> ClipboardHistoryModel::read_from_file(DeprecatedString const& path)
+ErrorOr<void> ClipboardHistoryModel::read_from_file(ByteString const& path)
 {
     m_path = path;
 
@@ -219,7 +219,7 @@ ErrorOr<void> ClipboardHistoryModel::write_to_file(bool rewrite_all)
     auto const write_element = [](Core::File& file, ClipboardItem const& item) -> ErrorOr<void> {
         if (!item.data_and_type.mime_type.starts_with("text/"sv))
             return {};
-        TRY(file.write_until_depleted(TRY(item.to_json()).to_deprecated_string().bytes()));
+        TRY(file.write_until_depleted(TRY(item.to_json()).to_byte_string().bytes()));
         TRY(file.write_until_depleted("\n"sv.bytes()));
         return {};
     };
diff --git a/Userland/Applets/ClipboardHistory/ClipboardHistoryModel.h b/Userland/Applets/ClipboardHistory/ClipboardHistoryModel.h
index bb9ea568509..0d33407c065 100644
--- a/Userland/Applets/ClipboardHistory/ClipboardHistoryModel.h
+++ b/Userland/Applets/ClipboardHistory/ClipboardHistoryModel.h
@@ -44,7 +44,7 @@ public:
     void clear();
     bool is_empty() { return m_history_items.is_empty(); }
 
-    ErrorOr<void> read_from_file(DeprecatedString const& path);
+    ErrorOr<void> read_from_file(ByteString const& path);
     ErrorOr<void> write_to_file(bool rewrite_all);
 
     ErrorOr<void> invalidate_model_and_file(bool rewrite_all);
@@ -64,10 +64,10 @@ private:
     virtual int column_count(const GUI::ModelIndex&) const override { return Column::__Count; }
 
     // ^GUI::Clipboard::ClipboardClient
-    virtual void clipboard_content_did_change(DeprecatedString const&) override;
+    virtual void clipboard_content_did_change(ByteString const&) override;
 
     Vector<ClipboardItem> m_history_items;
     size_t m_history_limit;
 
-    DeprecatedString m_path;
+    ByteString m_path;
 };
diff --git a/Userland/Applets/ClipboardHistory/main.cpp b/Userland/Applets/ClipboardHistory/main.cpp
index 09585638061..5f685691ec9 100644
--- a/Userland/Applets/ClipboardHistory/main.cpp
+++ b/Userland/Applets/ClipboardHistory/main.cpp
@@ -23,7 +23,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto app = TRY(GUI::Application::create(arguments));
     auto clipboard_config = TRY(Core::ConfigFile::open_for_app("ClipboardHistory"));
 
-    auto const default_path = DeprecatedString::formatted("{}/{}", Core::StandardPaths::data_directory(), "Clipboard/ClipboardHistory.json"sv);
+    auto const default_path = ByteString::formatted("{}/{}", Core::StandardPaths::data_directory(), "Clipboard/ClipboardHistory.json"sv);
     auto const clipboard_file_path = clipboard_config->read_entry("Clipboard", "ClipboardFilePath", default_path);
     auto const parent_path = LexicalPath(clipboard_file_path);
     TRY(Core::Directory::create(parent_path.dirname(), Core::Directory::CreateDirectories::Yes));
diff --git a/Userland/Applets/Keymap/KeymapStatusWidget.cpp b/Userland/Applets/Keymap/KeymapStatusWidget.cpp
index 7b6f2fae222..27afd9fa77d 100644
--- a/Userland/Applets/Keymap/KeymapStatusWidget.cpp
+++ b/Userland/Applets/Keymap/KeymapStatusWidget.cpp
@@ -63,10 +63,10 @@ ErrorOr<void> KeymapStatusWidget::refresh_menu()
     return {};
 }
 
-void KeymapStatusWidget::set_current_keymap(DeprecatedString const& keymap)
+void KeymapStatusWidget::set_current_keymap(ByteString const& keymap)
 {
     m_current_keymap = keymap;
-    set_tooltip(MUST(String::from_deprecated_string(keymap)));
+    set_tooltip(MUST(String::from_byte_string(keymap)));
     update();
 }
 
diff --git a/Userland/Applets/Keymap/KeymapStatusWidget.h b/Userland/Applets/Keymap/KeymapStatusWidget.h
index 8ee174cf2be..adaac8aa17a 100644
--- a/Userland/Applets/Keymap/KeymapStatusWidget.h
+++ b/Userland/Applets/Keymap/KeymapStatusWidget.h
@@ -15,7 +15,7 @@ class KeymapStatusWidget final : public GUI::Widget {
 
 public:
     virtual ~KeymapStatusWidget() override;
-    void set_current_keymap(DeprecatedString const& keymap);
+    void set_current_keymap(ByteString const& keymap);
 
 private:
     KeymapStatusWidget();
@@ -27,6 +27,6 @@ private:
 
     RefPtr<GUI::Menu> m_context_menu;
 
-    DeprecatedString m_current_keymap;
+    ByteString m_current_keymap;
     GUI::ActionGroup m_keymaps_group;
 };
diff --git a/Userland/Applets/Keymap/KeymapStatusWindow.cpp b/Userland/Applets/Keymap/KeymapStatusWindow.cpp
index a5ad58f0e23..03c1001d483 100644
--- a/Userland/Applets/Keymap/KeymapStatusWindow.cpp
+++ b/Userland/Applets/Keymap/KeymapStatusWindow.cpp
@@ -27,7 +27,7 @@ void KeymapStatusWindow::wm_event(GUI::WMEvent& event)
     }
 }
 
-void KeymapStatusWindow::set_keymap_text(DeprecatedString const& keymap)
+void KeymapStatusWindow::set_keymap_text(ByteString const& keymap)
 {
     m_status_widget->set_current_keymap(keymap);
 }
diff --git a/Userland/Applets/Keymap/KeymapStatusWindow.h b/Userland/Applets/Keymap/KeymapStatusWindow.h
index 0ba3c106dc8..0c6e5d9e4b8 100644
--- a/Userland/Applets/Keymap/KeymapStatusWindow.h
+++ b/Userland/Applets/Keymap/KeymapStatusWindow.h
@@ -23,5 +23,5 @@ private:
 
     RefPtr<KeymapStatusWidget> m_status_widget;
 
-    void set_keymap_text(DeprecatedString const& keymap);
+    void set_keymap_text(ByteString const& keymap);
 };
diff --git a/Userland/Applets/Network/main.cpp b/Userland/Applets/Network/main.cpp
index fd7f8e3655f..3e40d1a7298 100644
--- a/Userland/Applets/Network/main.cpp
+++ b/Userland/Applets/Network/main.cpp
@@ -113,8 +113,8 @@ private:
         int connected_adapters = 0;
         json.as_array().for_each([&adapter_info, &connected_adapters](auto& value) {
             auto& if_object = value.as_object();
-            auto ip_address = if_object.get_deprecated_string("ipv4_address"sv).value_or("no IP");
-            auto ifname = if_object.get_deprecated_string("name"sv).value();
+            auto ip_address = if_object.get_byte_string("ipv4_address"sv).value_or("no IP");
+            auto ifname = if_object.get_byte_string("name"sv).value();
             auto link_up = if_object.get_bool("link_up"sv).value();
             auto link_speed = if_object.get_i32("link_speed"sv).value();
 
diff --git a/Userland/Applications/3DFileViewer/main.cpp b/Userland/Applications/3DFileViewer/main.cpp
index bdd94df5b55..a7fd039b0a1 100644
--- a/Userland/Applications/3DFileViewer/main.cpp
+++ b/Userland/Applications/3DFileViewer/main.cpp
@@ -292,13 +292,13 @@ void GLContextWidget::timer_event(Core::TimerEvent&)
 bool GLContextWidget::load_file(String const& filename, NonnullOwnPtr<Core::File> file)
 {
     if (!filename.bytes_as_string_view().ends_with(".obj"sv)) {
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("Opening \"{}\" failed: invalid file type", filename), "Error"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(window(), ByteString::formatted("Opening \"{}\" failed: invalid file type", filename), "Error"sv, GUI::MessageBox::Type::Error);
         return false;
     }
 
     auto new_mesh = m_mesh_loader->load(filename, move(file));
     if (new_mesh.is_error()) {
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("Reading \"{}\" failed: {}", filename, new_mesh.release_error()), "Error"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(window(), ByteString::formatted("Reading \"{}\" failed: {}", filename, new_mesh.release_error()), "Error"sv, GUI::MessageBox::Type::Error);
         return false;
     }
 
@@ -330,7 +330,7 @@ bool GLContextWidget::load_file(String const& filename, NonnullOwnPtr<Core::File
     m_mesh = new_mesh.release_value();
     dbgln("3DFileViewer: mesh has {} triangles.", m_mesh->triangle_count());
 
-    window()->set_title(DeprecatedString::formatted("{} - 3D File Viewer", filename));
+    window()->set_title(ByteString::formatted("{} - 3D File Viewer", filename));
 
     return true;
 }
@@ -580,7 +580,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto file = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, filename);
     if (file.is_error()) {
         if (file.error().code() != ENOENT)
-            GUI::MessageBox::show(window, DeprecatedString::formatted("Opening \"{}\" failed: {}", filename, strerror(errno)), "Error"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(window, ByteString::formatted("Opening \"{}\" failed: {}", filename, strerror(errno)), "Error"sv, GUI::MessageBox::Type::Error);
         return 1;
     }
     widget->load_file(file.value().filename(), file.value().release_stream());
diff --git a/Userland/Applications/AnalogClock/AnalogClock.cpp b/Userland/Applications/AnalogClock/AnalogClock.cpp
index c421a5680e5..54524fe2846 100644
--- a/Userland/Applications/AnalogClock/AnalogClock.cpp
+++ b/Userland/Applications/AnalogClock/AnalogClock.cpp
@@ -130,7 +130,7 @@ void AnalogClock::paint_event(GUI::PaintEvent& event)
 
 void AnalogClock::update_title_date()
 {
-    window()->set_title(Core::DateTime::now().to_deprecated_string("%Y-%m-%d"sv));
+    window()->set_title(Core::DateTime::now().to_byte_string("%Y-%m-%d"sv));
 }
 
 void AnalogClock::context_menu_event(GUI::ContextMenuEvent& event)
diff --git a/Userland/Applications/AnalogClock/main.cpp b/Userland/Applications/AnalogClock/main.cpp
index ecb3b87d324..5f356feee79 100644
--- a/Userland/Applications/AnalogClock/main.cpp
+++ b/Userland/Applications/AnalogClock/main.cpp
@@ -26,7 +26,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto app_icon = TRY(GUI::Icon::try_create_default_icon("app-analog-clock"sv));
     auto window = GUI::Window::construct();
-    window->set_title(Core::DateTime::now().to_deprecated_string("%Y-%m-%d"sv));
+    window->set_title(Core::DateTime::now().to_byte_string("%Y-%m-%d"sv));
     window->set_icon(app_icon.bitmap_for_size(16));
     window->resize(170, 170);
     window->set_resizable(false);
diff --git a/Userland/Applications/Assistant/Providers.cpp b/Userland/Applications/Assistant/Providers.cpp
index c0c66a46873..11c5e85c4db 100644
--- a/Userland/Applications/Assistant/Providers.cpp
+++ b/Userland/Applications/Assistant/Providers.cpp
@@ -70,7 +70,7 @@ AppProvider::AppProvider()
     });
 }
 
-void AppProvider::query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
+void AppProvider::query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
 {
     if (query.starts_with('=') || query.starts_with('$'))
         return;
@@ -80,7 +80,7 @@ void AppProvider::query(DeprecatedString const& query, Function<void(Vector<Nonn
     for (auto const& app_file : m_app_file_cache) {
         auto query_and_arguments = query.split_limit(' ', 2);
         auto app_name = query_and_arguments.is_empty() ? query : query_and_arguments[0];
-        auto arguments = query_and_arguments.size() < 2 ? DeprecatedString::empty() : query_and_arguments[1];
+        auto arguments = query_and_arguments.size() < 2 ? ByteString::empty() : query_and_arguments[1];
         auto score = 0;
         if (app_name.equals_ignoring_ascii_case(app_file->name()))
             score = NumericLimits<int>::max();
@@ -98,7 +98,7 @@ void AppProvider::query(DeprecatedString const& query, Function<void(Vector<Nonn
     on_complete(move(results));
 }
 
-void CalculatorProvider::query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
+void CalculatorProvider::query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
 {
     if (!query.starts_with('='))
         return;
@@ -116,11 +116,11 @@ void CalculatorProvider::query(DeprecatedString const& query, Function<void(Vect
         return;
 
     auto result = completion.release_value();
-    DeprecatedString calculation;
+    ByteString calculation;
     if (!result.is_number()) {
         calculation = "0";
     } else {
-        calculation = result.to_string_without_side_effects().to_deprecated_string();
+        calculation = result.to_string_without_side_effects().to_byte_string();
     }
 
     Vector<NonnullRefPtr<Result>> results;
@@ -138,7 +138,7 @@ FileProvider::FileProvider()
     build_filesystem_cache();
 }
 
-void FileProvider::query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
+void FileProvider::query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
 {
     build_filesystem_cache();
 
@@ -147,7 +147,7 @@ void FileProvider::query(DeprecatedString const& query, Function<void(Vector<Non
 
     m_fuzzy_match_work = Threading::BackgroundAction<Optional<Vector<NonnullRefPtr<Result>>>>::construct(
         [this, query](auto& task) -> Optional<Vector<NonnullRefPtr<Result>>> {
-            BinaryHeap<int, DeprecatedString, MAX_SEARCH_RESULTS> sorted_results;
+            BinaryHeap<int, ByteString, MAX_SEARCH_RESULTS> sorted_results;
 
             for (auto& path : m_full_path_cache) {
                 if (task.is_canceled())
@@ -204,7 +204,7 @@ void FileProvider::build_filesystem_cache()
 
     (void)Threading::BackgroundAction<int>::construct(
         [this, strong_ref = NonnullRefPtr(*this)](auto&) {
-            DeprecatedString slash = "/";
+            ByteString slash = "/";
             auto timer = Core::ElapsedTimer::start_new();
             while (!m_work_queue.is_empty()) {
                 auto base_directory = m_work_queue.dequeue();
@@ -241,7 +241,7 @@ void FileProvider::build_filesystem_cache()
         });
 }
 
-void TerminalProvider::query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
+void TerminalProvider::query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
 {
     if (!query.starts_with('$'))
         return;
@@ -253,7 +253,7 @@ void TerminalProvider::query(DeprecatedString const& query, Function<void(Vector
     on_complete(move(results));
 }
 
-void URLProvider::query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
+void URLProvider::query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete)
 {
     if (query.is_empty() || query.starts_with('=') || query.starts_with('$'))
         return;
@@ -263,7 +263,7 @@ void URLProvider::query(DeprecatedString const& query, Function<void(Vector<Nonn
     if (url.scheme().is_empty())
         url.set_scheme("http"_string);
     if (url.host().has<Empty>() || url.host() == String {})
-        url.set_host(String::from_deprecated_string(query).release_value_but_fixme_should_propagate_errors());
+        url.set_host(String::from_byte_string(query).release_value_but_fixme_should_propagate_errors());
     if (url.path_segment_count() == 0)
         url.set_paths({ "" });
 
diff --git a/Userland/Applications/Assistant/Providers.h b/Userland/Applications/Assistant/Providers.h
index 091411c7f3d..b4450bcd7d7 100644
--- a/Userland/Applications/Assistant/Providers.h
+++ b/Userland/Applications/Assistant/Providers.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Queue.h>
 #include <AK/URL.h>
 #include <LibDesktop/AppFile.h>
@@ -27,7 +27,7 @@ public:
 
     virtual Gfx::Bitmap const* bitmap() const = 0;
 
-    DeprecatedString const& title() const { return m_title; }
+    ByteString const& title() const { return m_title; }
     String const& tooltip() const { return m_tooltip; }
     int score() const { return m_score; }
     bool equals(Result const& other) const
@@ -38,7 +38,7 @@ public:
     }
 
 protected:
-    Result(DeprecatedString title, String tooltip, int score = 0)
+    Result(ByteString title, String tooltip, int score = 0)
         : m_title(move(title))
         , m_tooltip(move(tooltip))
         , m_score(score)
@@ -46,14 +46,14 @@ protected:
     }
 
 private:
-    DeprecatedString m_title;
+    ByteString m_title;
     String m_tooltip;
     int m_score { 0 };
 };
 
 class AppResult final : public Result {
 public:
-    AppResult(RefPtr<Gfx::Bitmap const> bitmap, DeprecatedString title, String tooltip, NonnullRefPtr<Desktop::AppFile> af, DeprecatedString arguments, int score)
+    AppResult(RefPtr<Gfx::Bitmap const> bitmap, ByteString title, String tooltip, NonnullRefPtr<Desktop::AppFile> af, ByteString arguments, int score)
         : Result(move(title), move(tooltip), score)
         , m_app_file(move(af))
         , m_arguments(move(arguments))
@@ -67,13 +67,13 @@ public:
 
 private:
     NonnullRefPtr<Desktop::AppFile> m_app_file;
-    DeprecatedString m_arguments;
+    ByteString m_arguments;
     RefPtr<Gfx::Bitmap const> m_bitmap;
 };
 
 class CalculatorResult final : public Result {
 public:
-    explicit CalculatorResult(DeprecatedString title)
+    explicit CalculatorResult(ByteString title)
         : Result(move(title), "Copy to Clipboard"_string, 100)
         , m_bitmap(GUI::Icon::default_icon("app-calculator"sv).bitmap_for_size(16))
     {
@@ -89,7 +89,7 @@ private:
 
 class FileResult final : public Result {
 public:
-    explicit FileResult(DeprecatedString title, int score)
+    explicit FileResult(ByteString title, int score)
         : Result(move(title), String(), score)
     {
     }
@@ -101,7 +101,7 @@ public:
 
 class TerminalResult final : public Result {
 public:
-    explicit TerminalResult(DeprecatedString command)
+    explicit TerminalResult(ByteString command)
         : Result(move(command), "Run command in Terminal"_string, 100)
         , m_bitmap(GUI::Icon::default_icon("app-terminal"sv).bitmap_for_size(16))
     {
@@ -118,7 +118,7 @@ private:
 class URLResult final : public Result {
 public:
     explicit URLResult(const URL& url)
-        : Result(url.to_deprecated_string(), "Open URL in Browser"_string, 50)
+        : Result(url.to_byte_string(), "Open URL in Browser"_string, 50)
         , m_bitmap(GUI::Icon::default_icon("app-browser"sv).bitmap_for_size(16))
     {
     }
@@ -135,14 +135,14 @@ class Provider : public RefCounted<Provider> {
 public:
     virtual ~Provider() = default;
 
-    virtual void query(DeprecatedString const&, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) = 0;
+    virtual void query(ByteString const&, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) = 0;
 };
 
 class AppProvider final : public Provider {
 public:
     AppProvider();
 
-    void query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
+    void query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
 
 private:
     Vector<NonnullRefPtr<Desktop::AppFile>> m_app_file_cache;
@@ -150,31 +150,31 @@ private:
 
 class CalculatorProvider final : public Provider {
 public:
-    void query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
+    void query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
 };
 
 class FileProvider final : public Provider {
 public:
     FileProvider();
 
-    void query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
+    void query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
     void build_filesystem_cache();
 
 private:
     RefPtr<Threading::BackgroundAction<Optional<Vector<NonnullRefPtr<Result>>>>> m_fuzzy_match_work;
     bool m_building_cache { false };
-    Vector<DeprecatedString> m_full_path_cache;
-    Queue<DeprecatedString> m_work_queue;
+    Vector<ByteString> m_full_path_cache;
+    Queue<ByteString> m_work_queue;
 };
 
 class TerminalProvider final : public Provider {
 public:
-    void query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
+    void query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
 };
 
 class URLProvider final : public Provider {
 public:
-    void query(DeprecatedString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
+    void query(ByteString const& query, Function<void(Vector<NonnullRefPtr<Result>>)> on_complete) override;
 };
 
 }
diff --git a/Userland/Applications/Assistant/main.cpp b/Userland/Applications/Assistant/main.cpp
index 83aec39c260..a3cd79c3948 100644
--- a/Userland/Applications/Assistant/main.cpp
+++ b/Userland/Applications/Assistant/main.cpp
@@ -7,7 +7,7 @@
 
 #include "Providers.h"
 #include <AK/Array.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/LexicalPath.h>
 #include <AK/QuickSort.h>
@@ -40,7 +40,7 @@ struct AppState {
     size_t visible_result_count { 0 };
 
     Threading::Mutex lock;
-    DeprecatedString last_query;
+    ByteString last_query;
 };
 
 class ResultRow final : public GUI::Button {
@@ -57,7 +57,7 @@ class ResultRow final : public GUI::Button {
             if (!m_context_menu) {
                 m_context_menu = GUI::Menu::construct();
 
-                if (LexicalPath path { text().to_deprecated_string() }; path.is_absolute()) {
+                if (LexicalPath path { text().to_byte_string() }; path.is_absolute()) {
                     m_context_menu->add_action(GUI::Action::create("&Show in File Manager", MUST(Gfx::Bitmap::load_from_file("/res/icons/16x16/app-file-manager.png"sv)), [=](auto&) {
                         Desktop::Launcher::open(URL::create_with_file_scheme(path.dirname(), path.basename()));
                     }));
@@ -86,7 +86,7 @@ public:
 
     Function<void(Vector<NonnullRefPtr<Result const>>&&)> on_new_results;
 
-    void search(DeprecatedString const& query)
+    void search(ByteString const& query)
     {
         auto should_display_precached_results = false;
         for (size_t i = 0; i < ProviderCount; ++i) {
@@ -139,7 +139,7 @@ private:
     Array<NonnullRefPtr<Provider>, ProviderCount> m_providers;
 
     Threading::Mutex m_mutex;
-    HashMap<DeprecatedString, Array<OwnPtr<Vector<NonnullRefPtr<Result>>>, ProviderCount>> m_result_cache;
+    HashMap<ByteString, Array<OwnPtr<Vector<NonnullRefPtr<Result>>>, ProviderCount>> m_result_cache;
 };
 
 }
@@ -249,7 +249,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             auto& result = app_state.results[i];
             auto& match = results_container.add<Assistant::ResultRow>();
             match.set_icon(result->bitmap());
-            match.set_text(String::from_deprecated_string(result->title()).release_value_but_fixme_should_propagate_errors());
+            match.set_text(String::from_byte_string(result->title()).release_value_but_fixme_should_propagate_errors());
             match.set_tooltip(result->tooltip());
             match.on_click = [&result](auto) {
                 result->activate();
diff --git a/Userland/Applications/Browser/BookmarksBarWidget.cpp b/Userland/Applications/Browser/BookmarksBarWidget.cpp
index 6b854e52029..56701c9cede 100644
--- a/Userland/Applications/Browser/BookmarksBarWidget.cpp
+++ b/Userland/Applications/Browser/BookmarksBarWidget.cpp
@@ -88,12 +88,12 @@ private:
         };
     }
 
-    DeprecatedString title() const
+    ByteString title() const
     {
         return m_title_textbox->text();
     }
 
-    DeprecatedString url() const
+    ByteString url() const
     {
         return m_url_textbox->text();
     }
@@ -111,7 +111,7 @@ BookmarksBarWidget& BookmarksBarWidget::the()
     return *s_the;
 }
 
-BookmarksBarWidget::BookmarksBarWidget(DeprecatedString const& bookmarks_file, bool enabled)
+BookmarksBarWidget::BookmarksBarWidget(ByteString const& bookmarks_file, bool enabled)
 {
     s_the = this;
     set_layout<GUI::HorizontalBoxLayout>(2, 0);
@@ -207,8 +207,8 @@ void BookmarksBarWidget::model_did_update(unsigned)
     int width = 0;
     for (int item_index = 0; item_index < model()->row_count(); ++item_index) {
 
-        auto title = model()->index(item_index, 0).data().to_deprecated_string();
-        auto url = model()->index(item_index, 1).data().to_deprecated_string();
+        auto title = model()->index(item_index, 0).data().to_byte_string();
+        auto url = model()->index(item_index, 1).data().to_byte_string();
 
         Gfx::IntRect rect { width, 0, font().width_rounded_up(title) + 32, height() };
 
@@ -216,12 +216,12 @@ void BookmarksBarWidget::model_did_update(unsigned)
         m_bookmarks.append(button);
 
         button.set_button_style(Gfx::ButtonStyle::Coolbar);
-        button.set_text(String::from_deprecated_string(title).release_value_but_fixme_should_propagate_errors());
+        button.set_text(String::from_byte_string(title).release_value_but_fixme_should_propagate_errors());
         button.set_icon(g_icon_bag.filetype_html);
         button.set_fixed_size(font().width(title) + 32, 20);
         button.set_relative_rect(rect);
         button.set_focus_policy(GUI::FocusPolicy::TabFocus);
-        button.set_tooltip(MUST(String::from_deprecated_string(url)));
+        button.set_tooltip(MUST(String::from_byte_string(url)));
         button.set_allowed_mouse_buttons_for_pressing(GUI::MouseButton::Primary | GUI::MouseButton::Middle);
 
         button.on_click = [title, url, this](auto) {
@@ -275,7 +275,7 @@ void BookmarksBarWidget::update_content_size()
         for (size_t i = m_last_visible_index; i < m_bookmarks.size(); ++i) {
             auto& bookmark = m_bookmarks.at(i);
             bookmark->set_visible(false);
-            m_additional_menu->add_action(GUI::Action::create(bookmark->text().to_deprecated_string(), g_icon_bag.filetype_html, [&](auto&) { bookmark->on_click(0); }));
+            m_additional_menu->add_action(GUI::Action::create(bookmark->text().to_byte_string(), g_icon_bag.filetype_html, [&](auto&) { bookmark->on_click(0); }));
         }
     }
 }
@@ -284,7 +284,7 @@ bool BookmarksBarWidget::contains_bookmark(StringView url)
 {
     for (int item_index = 0; item_index < model()->row_count(); ++item_index) {
 
-        auto item_url = model()->index(item_index, 1).data().to_deprecated_string();
+        auto item_url = model()->index(item_index, 1).data().to_byte_string();
         if (item_url == url) {
             return true;
         }
@@ -296,7 +296,7 @@ ErrorOr<void> BookmarksBarWidget::remove_bookmark(StringView url)
 {
     for (int item_index = 0; item_index < model()->row_count(); ++item_index) {
 
-        auto item_url = model()->index(item_index, 1).data().to_deprecated_string();
+        auto item_url = model()->index(item_index, 1).data().to_byte_string();
         if (item_url == url) {
             auto& json_model = *static_cast<GUI::JsonArrayModel*>(model());
 
@@ -332,7 +332,7 @@ ErrorOr<void> BookmarksBarWidget::add_bookmark(StringView url, StringView title)
 
     auto model_has_updated = false;
     for (int item_index = 0; item_index < model()->row_count(); item_index++) {
-        auto item_url = model()->index(item_index, 1).data().to_deprecated_string();
+        auto item_url = model()->index(item_index, 1).data().to_byte_string();
 
         if (item_url == url) {
             TRY(update_model(values, [item_index](auto& model, auto&& values) {
@@ -355,8 +355,8 @@ ErrorOr<void> BookmarksBarWidget::add_bookmark(StringView url, StringView title)
 ErrorOr<void> BookmarksBarWidget::edit_bookmark(StringView url)
 {
     for (int item_index = 0; item_index < model()->row_count(); ++item_index) {
-        auto item_title = model()->index(item_index, 0).data().to_deprecated_string();
-        auto item_url = model()->index(item_index, 1).data().to_deprecated_string();
+        auto item_title = model()->index(item_index, 0).data().to_byte_string();
+        auto item_url = model()->index(item_index, 1).data().to_byte_string();
 
         if (item_url == url) {
             auto values = BookmarkEditor::edit_bookmark(window(), item_title, item_url, PerformEditOn::ExistingBookmark);
diff --git a/Userland/Applications/Browser/BookmarksBarWidget.h b/Userland/Applications/Browser/BookmarksBarWidget.h
index 7741eb707f1..b4640fd0c0f 100644
--- a/Userland/Applications/Browser/BookmarksBarWidget.h
+++ b/Userland/Applications/Browser/BookmarksBarWidget.h
@@ -32,8 +32,8 @@ public:
         InNewWindow
     };
 
-    Function<void(DeprecatedString const& url, Open)> on_bookmark_click;
-    Function<void(DeprecatedString const&, DeprecatedString const&)> on_bookmark_hover;
+    Function<void(ByteString const& url, Open)> on_bookmark_click;
+    Function<void(ByteString const&, ByteString const&)> on_bookmark_hover;
     Function<void()> on_bookmark_change;
 
     bool contains_bookmark(StringView url);
@@ -48,7 +48,7 @@ public:
     }
 
 private:
-    BookmarksBarWidget(DeprecatedString const&, bool enabled);
+    BookmarksBarWidget(ByteString const&, bool enabled);
 
     // ^GUI::ModelClient
     virtual void model_did_update(unsigned) override;
@@ -67,7 +67,7 @@ private:
 
     RefPtr<GUI::Menu> m_context_menu;
     RefPtr<GUI::Action> m_context_menu_default_action;
-    DeprecatedString m_context_menu_url;
+    ByteString m_context_menu_url;
 
     Vector<NonnullRefPtr<GUI::Button>> m_bookmarks;
 
diff --git a/Userland/Applications/Browser/Browser.h b/Userland/Applications/Browser/Browser.h
index 5e940301315..a1d4e07b4fb 100644
--- a/Userland/Applications/Browser/Browser.h
+++ b/Userland/Applications/Browser/Browser.h
@@ -6,22 +6,22 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/String.h>
 #include <Applications/Browser/IconBag.h>
 
 namespace Browser {
 
-extern DeprecatedString g_home_url;
-extern DeprecatedString g_new_tab_url;
-extern DeprecatedString g_search_engine;
+extern ByteString g_home_url;
+extern ByteString g_new_tab_url;
+extern ByteString g_search_engine;
 extern Vector<String> g_content_filters;
 extern bool g_content_filters_enabled;
 extern Vector<String> g_autoplay_allowlist;
 extern bool g_autoplay_allowed_on_all_websites;
-extern Vector<DeprecatedString> g_proxies;
-extern HashMap<DeprecatedString, size_t> g_proxy_mappings;
+extern Vector<ByteString> g_proxies;
+extern HashMap<ByteString, size_t> g_proxy_mappings;
 extern IconBag g_icon_bag;
-extern DeprecatedString g_webdriver_content_ipc_path;
+extern ByteString g_webdriver_content_ipc_path;
 
 }
diff --git a/Userland/Applications/Browser/BrowserWindow.cpp b/Userland/Applications/Browser/BrowserWindow.cpp
index ee16b1a490f..3a16d7159c3 100644
--- a/Userland/Applications/Browser/BrowserWindow.cpp
+++ b/Userland/Applications/Browser/BrowserWindow.cpp
@@ -41,12 +41,12 @@
 
 namespace Browser {
 
-static DeprecatedString bookmarks_file_path()
+static ByteString bookmarks_file_path()
 {
     StringBuilder builder;
     builder.append(Core::StandardPaths::config_directory());
     builder.append("/bookmarks.json"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 BrowserWindow::BrowserWindow(WebView::CookieJar& cookie_jar, Vector<URL> const& initial_urls)
@@ -275,11 +275,11 @@ void BrowserWindow::build_menus()
 
     m_change_homepage_action = GUI::Action::create(
         "Set Homepage URL...", g_icon_bag.go_home, [this](auto&) {
-            String homepage_url = String::from_deprecated_string(Config::read_string("Browser"sv, "Preferences"sv, "Home"sv, Browser::default_homepage_url())).release_value_but_fixme_should_propagate_errors();
+            String homepage_url = String::from_byte_string(Config::read_string("Browser"sv, "Preferences"sv, "Home"sv, Browser::default_homepage_url())).release_value_but_fixme_should_propagate_errors();
             if (GUI::InputBox::show(this, homepage_url, "Enter a URL:"sv, "Change Homepage"sv) == GUI::InputBox::ExecResult::OK) {
                 if (URL(homepage_url).is_valid()) {
                     Config::write_string("Browser"sv, "Preferences"sv, "Home"sv, homepage_url);
-                    Browser::g_home_url = homepage_url.to_deprecated_string();
+                    Browser::g_home_url = homepage_url.to_byte_string();
                 } else {
                     GUI::MessageBox::show_error(this, "The URL you have entered is not valid"sv);
                 }
@@ -412,7 +412,7 @@ void BrowserWindow::build_menus()
             m_disable_user_agent_spoofing->activate();
             return;
         }
-        active_tab().view().debug_request("spoof-user-agent", user_agent.to_deprecated_string());
+        active_tab().view().debug_request("spoof-user-agent", user_agent.to_byte_string());
         action.set_status_tip(user_agent);
     });
     spoof_user_agent_menu->add_action(custom_user_agent);
@@ -497,7 +497,7 @@ ErrorOr<void> BrowserWindow::load_search_engines(GUI::Menu& settings_menu)
             return;
         }
 
-        g_search_engine = search_engine.to_deprecated_string();
+        g_search_engine = search_engine.to_byte_string();
         Config::write_string("Browser"sv, "Preferences"sv, "SearchEngine"sv, g_search_engine);
         action.set_status_tip(search_engine);
     });
@@ -506,7 +506,7 @@ ErrorOr<void> BrowserWindow::load_search_engines(GUI::Menu& settings_menu)
 
     if (!search_engine_set && !g_search_engine.is_empty()) {
         custom_search_engine_action->set_checked(true);
-        custom_search_engine_action->set_status_tip(TRY(String::from_deprecated_string(g_search_engine)));
+        custom_search_engine_action->set_status_tip(TRY(String::from_byte_string(g_search_engine)));
     }
 
     return {};
@@ -526,7 +526,7 @@ void BrowserWindow::set_window_title_for_tab(Tab const& tab)
 {
     auto& title = tab.title();
     auto url = tab.url();
-    set_title(DeprecatedString::formatted("{} - Ladybird", title.is_empty() ? url.to_deprecated_string() : title));
+    set_title(ByteString::formatted("{} - Ladybird", title.is_empty() ? url.to_byte_string() : title));
 }
 
 Tab& BrowserWindow::create_new_tab(URL const& url, Web::HTML::ActivateTab activate)
@@ -536,7 +536,7 @@ Tab& BrowserWindow::create_new_tab(URL const& url, Web::HTML::ActivateTab activa
     m_tab_widget->set_bar_visible(!is_fullscreen() && m_tab_widget->children().size() > 1);
 
     new_tab.on_title_change = [this, &new_tab](auto& title) {
-        m_tab_widget->set_tab_title(new_tab, String::from_deprecated_string(title).release_value_but_fixme_should_propagate_errors());
+        m_tab_widget->set_tab_title(new_tab, String::from_byte_string(title).release_value_but_fixme_should_propagate_errors());
         if (m_tab_widget->active_widget() == &new_tab)
             set_window_title_for_tab(new_tab);
     };
@@ -582,7 +582,7 @@ Tab& BrowserWindow::create_new_tab(URL const& url, Web::HTML::ActivateTab activa
         return m_cookie_jar.get_named_cookie(url, name);
     };
 
-    new_tab.on_get_cookie = [this](auto& url, auto source) -> DeprecatedString {
+    new_tab.on_get_cookie = [this](auto& url, auto source) -> ByteString {
         return m_cookie_jar.get_cookie(url, source);
     };
 
@@ -622,7 +622,7 @@ Tab& BrowserWindow::create_new_tab(URL const& url, Web::HTML::ActivateTab activa
 
 void BrowserWindow::create_new_window(URL const& url)
 {
-    GUI::Process::spawn_or_show_error(this, "/bin/Browser"sv, Array { url.to_deprecated_string() });
+    GUI::Process::spawn_or_show_error(this, "/bin/Browser"sv, Array { url.to_byte_string() });
 }
 
 void BrowserWindow::content_filters_changed()
diff --git a/Userland/Applications/Browser/CookiesModel.cpp b/Userland/Applications/Browser/CookiesModel.cpp
index 4466599cc16..fbae8291045 100644
--- a/Userland/Applications/Browser/CookiesModel.cpp
+++ b/Userland/Applications/Browser/CookiesModel.cpp
@@ -95,7 +95,7 @@ GUI::Model::MatchResult CookiesModel::data_matches(GUI::ModelIndex const& index,
         return { TriState::True };
 
     auto const& cookie = m_cookies[index.row()];
-    auto haystack = DeprecatedString::formatted("{} {} {} {}", cookie.domain, cookie.path, cookie.name, cookie.value);
+    auto haystack = ByteString::formatted("{} {} {} {}", cookie.domain, cookie.path, cookie.name, cookie.value);
     auto match_result = fuzzy_match(needle, haystack);
     if (match_result.score > 0)
         return { TriState::True, match_result.score };
diff --git a/Userland/Applications/Browser/DownloadWidget.cpp b/Userland/Applications/Browser/DownloadWidget.cpp
index 0ef34f2677e..82e68c5d834 100644
--- a/Userland/Applications/Browser/DownloadWidget.cpp
+++ b/Userland/Applications/Browser/DownloadWidget.cpp
@@ -35,7 +35,7 @@ DownloadWidget::DownloadWidget(const URL& url)
         builder.append(Core::StandardPaths::downloads_directory());
         builder.append('/');
         builder.append(m_url.basename());
-        m_destination_path = builder.to_deprecated_string();
+        m_destination_path = builder.to_byte_string();
     }
 
     auto close_on_finish = Config::read_bool("Browser"sv, "Preferences"sv, "CloseDownloadWidgetOnFinish"sv, Browser::default_close_download_widget_on_finish);
@@ -50,7 +50,7 @@ DownloadWidget::DownloadWidget(const URL& url)
     {
         auto file_or_error = Core::File::open(m_destination_path, Core::File::OpenMode::Write);
         if (file_or_error.is_error()) {
-            GUI::MessageBox::show(window(), DeprecatedString::formatted("Cannot open {} for writing", m_destination_path), "Download failed"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(window(), ByteString::formatted("Cannot open {} for writing", m_destination_path), "Download failed"sv, GUI::MessageBox::Type::Error);
             window()->close();
             return;
         }
@@ -86,7 +86,7 @@ DownloadWidget::DownloadWidget(const URL& url)
     m_progress_label->set_fixed_height(16);
     m_progress_label->set_text_wrapping(Gfx::TextWrapping::DontWrap);
 
-    auto destination_label_path = LexicalPath(m_destination_path).dirname().to_deprecated_string();
+    auto destination_label_path = LexicalPath(m_destination_path).dirname().to_byte_string();
 
     auto& destination_label = add<GUI::Label>(String::formatted("To: {}", destination_label_path).release_value_but_fixme_should_propagate_errors());
     destination_label.set_text_alignment(Gfx::TextAlignment::CenterLeft);
@@ -145,7 +145,7 @@ void DownloadWidget::did_progress(Optional<u64> total_size, u64 downloaded_size)
         }
         builder.append(" of "sv);
         builder.append(m_url.basename());
-        window()->set_title(builder.to_deprecated_string());
+        window()->set_title(builder.to_byte_string());
     }
 }
 
@@ -164,7 +164,7 @@ void DownloadWidget::did_finish(bool success)
     m_cancel_button->update();
 
     if (!success) {
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("Download failed for some reason"), "Download failed"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(window(), ByteString::formatted("Download failed for some reason"), "Download failed"sv, GUI::MessageBox::Type::Error);
         window()->close();
         return;
     }
diff --git a/Userland/Applications/Browser/DownloadWidget.h b/Userland/Applications/Browser/DownloadWidget.h
index 3e131476ddd..4d15dc3375c 100644
--- a/Userland/Applications/Browser/DownloadWidget.h
+++ b/Userland/Applications/Browser/DownloadWidget.h
@@ -29,7 +29,7 @@ private:
     void did_finish(bool success);
 
     URL m_url;
-    DeprecatedString m_destination_path;
+    ByteString m_destination_path;
     RefPtr<Web::ResourceLoaderConnectorRequest> m_download;
     RefPtr<GUI::Progressbar> m_progressbar;
     RefPtr<GUI::Label> m_progress_label;
diff --git a/Userland/Applications/Browser/History/HistoryModel.cpp b/Userland/Applications/Browser/History/HistoryModel.cpp
index 7ee0216a78f..78941566060 100644
--- a/Userland/Applications/Browser/History/HistoryModel.cpp
+++ b/Userland/Applications/Browser/History/HistoryModel.cpp
@@ -79,7 +79,7 @@ GUI::Model::MatchResult HistoryModel::data_matches(GUI::ModelIndex const& index,
         return { TriState::True };
 
     auto const& history_entry = m_entries[index.row()];
-    auto haystack = DeprecatedString::formatted("{} {}", history_entry.title, history_entry.url.serialize());
+    auto haystack = ByteString::formatted("{} {}", history_entry.title, history_entry.url.serialize());
     auto match_result = fuzzy_match(needle, haystack);
     if (match_result.score > 0)
         return { TriState::True, match_result.score };
diff --git a/Userland/Applications/Browser/InspectorWidget.cpp b/Userland/Applications/Browser/InspectorWidget.cpp
index b67b77dbcb7..b6e8c91f67c 100644
--- a/Userland/Applications/Browser/InspectorWidget.cpp
+++ b/Userland/Applications/Browser/InspectorWidget.cpp
@@ -84,7 +84,7 @@ InspectorWidget::InspectorWidget(WebView::OutOfProcessWebView& content_view)
     };
 
     m_inspector_client->on_requested_dom_node_tag_context_menu = [this](auto position, auto const& tag) {
-        m_edit_node_action->set_text(DeprecatedString::formatted("&Edit \"{}\"", tag));
+        m_edit_node_action->set_text(ByteString::formatted("&Edit \"{}\"", tag));
         m_copy_node_action->set_text("&Copy HTML");
 
         m_dom_node_tag_context_menu->popup(to_widget_position(position));
@@ -94,9 +94,9 @@ InspectorWidget::InspectorWidget(WebView::OutOfProcessWebView& content_view)
         static constexpr size_t MAX_ATTRIBUTE_VALUE_LENGTH = 32;
 
         m_copy_node_action->set_text("&Copy HTML");
-        m_edit_node_action->set_text(DeprecatedString::formatted("&Edit attribute \"{}\"", attribute.name));
-        m_remove_attribute_action->set_text(DeprecatedString::formatted("&Remove attribute \"{}\"", attribute.name));
-        m_copy_attribute_value_action->set_text(DeprecatedString::formatted("Copy attribute &value \"{:.{}}{}\"",
+        m_edit_node_action->set_text(ByteString::formatted("&Edit attribute \"{}\"", attribute.name));
+        m_remove_attribute_action->set_text(ByteString::formatted("&Remove attribute \"{}\"", attribute.name));
+        m_copy_attribute_value_action->set_text(ByteString::formatted("Copy attribute &value \"{:.{}}{}\"",
             attribute.value, MAX_ATTRIBUTE_VALUE_LENGTH,
             attribute.value.bytes_as_string_view().length() > MAX_ATTRIBUTE_VALUE_LENGTH ? "..."sv : ""sv));
 
diff --git a/Userland/Applications/Browser/StorageModel.cpp b/Userland/Applications/Browser/StorageModel.cpp
index 724914ef545..42cca352aea 100644
--- a/Userland/Applications/Browser/StorageModel.cpp
+++ b/Userland/Applications/Browser/StorageModel.cpp
@@ -85,7 +85,7 @@ GUI::Model::MatchResult StorageModel::data_matches(GUI::ModelIndex const& index,
     auto const& local_storage_key = keys[index.row()];
     auto const& local_storage_value = m_local_storage_entries.get(local_storage_key).value_or({});
 
-    auto haystack = DeprecatedString::formatted("{} {}", local_storage_key, local_storage_value);
+    auto haystack = ByteString::formatted("{} {}", local_storage_key, local_storage_value);
     auto match_result = fuzzy_match(needle, haystack);
     if (match_result.score > 0)
         return { TriState::True, match_result.score };
diff --git a/Userland/Applications/Browser/Tab.cpp b/Userland/Applications/Browser/Tab.cpp
index 0b2a15835b4..ca886b43aa4 100644
--- a/Userland/Applications/Browser/Tab.cpp
+++ b/Userland/Applications/Browser/Tab.cpp
@@ -58,13 +58,13 @@ void Tab::start_download(const URL& url)
 {
     auto window = GUI::Window::construct(&this->window());
     window->resize(300, 170);
-    window->set_title(DeprecatedString::formatted("0% of {}", url.basename()));
+    window->set_title(ByteString::formatted("0% of {}", url.basename()));
     window->set_resizable(false);
     (void)window->set_main_widget<DownloadWidget>(url);
     window->show();
 }
 
-void Tab::view_source(const URL& url, DeprecatedString const& source)
+void Tab::view_source(const URL& url, ByteString const& source)
 {
     auto window = GUI::Window::construct(&this->window());
     auto editor = window->set_main_widget<GUI::TextEditor>();
@@ -74,7 +74,7 @@ void Tab::view_source(const URL& url, DeprecatedString const& source)
     editor->set_ruler_visible(true);
     editor->set_visualize_trailing_whitespace(false);
     window->resize(640, 480);
-    window->set_title(url.to_deprecated_string());
+    window->set_title(url.to_byte_string());
     window->set_icon(g_icon_bag.filetype_text);
     window->set_window_mode(GUI::WindowMode::Modeless);
     window->show();
@@ -132,7 +132,7 @@ Tab::Tab(BrowserWindow& window)
         m_go_back_context_menu = GUI::Menu::construct();
         for (auto& url : m_history.get_back_title_history()) {
             i++;
-            m_go_back_context_menu->add_action(GUI::Action::create(url.to_deprecated_string(), g_icon_bag.filetype_html, [this, i](auto&) { go_back(i); }));
+            m_go_back_context_menu->add_action(GUI::Action::create(url.to_byte_string(), g_icon_bag.filetype_html, [this, i](auto&) { go_back(i); }));
         }
         m_go_back_context_menu->popup(go_back_button.screen_relative_rect().bottom_left().moved_up(1));
     };
@@ -145,7 +145,7 @@ Tab::Tab(BrowserWindow& window)
         m_go_forward_context_menu = GUI::Menu::construct();
         for (auto& url : m_history.get_forward_title_history()) {
             i++;
-            m_go_forward_context_menu->add_action(GUI::Action::create(url.to_deprecated_string(), g_icon_bag.filetype_html, [this, i](auto&) { go_forward(i); }));
+            m_go_forward_context_menu->add_action(GUI::Action::create(url.to_byte_string(), g_icon_bag.filetype_html, [this, i](auto&) { go_forward(i); }));
         }
         m_go_forward_context_menu->popup(go_forward_button.screen_relative_rect().bottom_left().moved_up(1));
     };
@@ -220,7 +220,7 @@ Tab::Tab(BrowserWindow& window)
         update_status();
 
         m_location_box->set_icon(nullptr);
-        m_location_box->set_text(url.to_deprecated_string());
+        m_location_box->set_text(url.to_byte_string());
 
         // don't add to history if back or forward is pressed
         if (!m_is_history_navigation)
@@ -228,7 +228,7 @@ Tab::Tab(BrowserWindow& window)
         m_is_history_navigation = false;
 
         update_actions();
-        update_bookmark_button(url.to_deprecated_string());
+        update_bookmark_button(url.to_byte_string());
 
         if (m_dom_inspector_widget)
             m_dom_inspector_widget->reset();
@@ -353,7 +353,7 @@ Tab::Tab(BrowserWindow& window)
             GUI::Clipboard::the().set_bitmap(*m_image_context_menu_bitmap.bitmap());
     }));
     m_image_context_menu->add_action(GUI::Action::create("Copy Image &URL", g_icon_bag.copy, [this](auto&) {
-        GUI::Clipboard::the().set_plain_text(m_image_context_menu_url.to_deprecated_string());
+        GUI::Clipboard::the().set_plain_text(m_image_context_menu_url.to_byte_string());
     }));
     m_image_context_menu->add_separator();
     m_image_context_menu->add_action(GUI::Action::create("&Download", g_icon_bag.download, [this](auto&) {
@@ -397,7 +397,7 @@ Tab::Tab(BrowserWindow& window)
     }));
     m_audio_context_menu->add_separator();
     m_audio_context_menu->add_action(GUI::Action::create("Copy Audio &URL", g_icon_bag.copy, [this](auto&) {
-        GUI::Clipboard::the().set_plain_text(m_media_context_menu_url.to_deprecated_string());
+        GUI::Clipboard::the().set_plain_text(m_media_context_menu_url.to_byte_string());
     }));
     m_audio_context_menu->add_separator();
     m_audio_context_menu->add_action(GUI::Action::create("&Download", g_icon_bag.download, [this](auto&) {
@@ -420,7 +420,7 @@ Tab::Tab(BrowserWindow& window)
     }));
     m_video_context_menu->add_separator();
     m_video_context_menu->add_action(GUI::Action::create("Copy Video &URL", g_icon_bag.copy, [this](auto&) {
-        GUI::Clipboard::the().set_plain_text(m_media_context_menu_url.to_deprecated_string());
+        GUI::Clipboard::the().set_plain_text(m_media_context_menu_url.to_byte_string());
     }));
     m_video_context_menu->add_separator();
     m_video_context_menu->add_action(GUI::Action::create("&Download", g_icon_bag.download, [this](auto&) {
@@ -490,7 +490,7 @@ Tab::Tab(BrowserWindow& window)
         return {};
     };
 
-    view().on_get_cookie = [this](auto& url, auto source) -> DeprecatedString {
+    view().on_get_cookie = [this](auto& url, auto source) -> ByteString {
         if (on_get_cookie)
             return on_get_cookie(url, source);
         return {};
@@ -609,7 +609,7 @@ Tab::Tab(BrowserWindow& window)
     m_statusbar = *find_descendant_of_type_named<GUI::Statusbar>("statusbar");
 
     view().on_link_hover = [this](auto& url) {
-        update_status(String::from_deprecated_string(url.to_deprecated_string()).release_value_but_fixme_should_propagate_errors());
+        update_status(String::from_byte_string(url.to_byte_string()).release_value_but_fixme_should_propagate_errors());
     };
 
     view().on_link_unhover = [this]() {
@@ -631,7 +631,7 @@ Tab::Tab(BrowserWindow& window)
     };
 
     view().on_insert_clipboard_entry = [](auto const& data, auto const&, auto const& mime_type) {
-        GUI::Clipboard::the().set_data(data.bytes(), mime_type.to_deprecated_string());
+        GUI::Clipboard::the().set_data(data.bytes(), mime_type.to_byte_string());
     };
 
     m_tab_context_menu = GUI::Menu::construct();
@@ -705,7 +705,7 @@ Tab::Tab(BrowserWindow& window)
 
         if (m_page_context_menu_search_text.has_value()) {
             auto action_text = WebView::format_search_query_for_display(g_search_engine, *m_page_context_menu_search_text);
-            search_selected_text_action->set_text(action_text.to_deprecated_string());
+            search_selected_text_action->set_text(action_text.to_byte_string());
             search_selected_text_action->set_visible(true);
         } else {
             search_selected_text_action->set_visible(false);
@@ -719,7 +719,7 @@ Tab::Tab(BrowserWindow& window)
 void Tab::select_dropdown_add_item(GUI::Menu& menu, Web::HTML::SelectItem const& item)
 {
     if (item.type == Web::HTML::SelectItem::Type::OptionGroup) {
-        auto subtitle = GUI::Action::create(MUST(DeprecatedString::from_utf8(item.label.value_or(""_string))), nullptr);
+        auto subtitle = GUI::Action::create(MUST(ByteString::from_utf8(item.label.value_or(""_string))), nullptr);
         subtitle->set_enabled(false);
         menu.add_action(subtitle);
 
@@ -728,7 +728,7 @@ void Tab::select_dropdown_add_item(GUI::Menu& menu, Web::HTML::SelectItem const&
         }
     }
     if (item.type == Web::HTML::SelectItem::Type::Option) {
-        auto action = GUI::Action::create(MUST(DeprecatedString::from_utf8(item.label.value_or(""_string))), [this, item](GUI::Action&) {
+        auto action = GUI::Action::create(MUST(ByteString::from_utf8(item.label.value_or(""_string))), [this, item](GUI::Action&) {
             m_select_dropdown_closed_by_action = true;
             view().select_dropdown_closed(item.value.value_or(""_string));
         });
@@ -804,7 +804,7 @@ void Tab::update_actions()
 
 ErrorOr<void> Tab::bookmark_current_url()
 {
-    auto url = this->url().to_deprecated_string();
+    auto url = this->url().to_byte_string();
     if (BookmarksBarWidget::the().contains_bookmark(url)) {
         TRY(BookmarksBarWidget::the().remove_bookmark(url));
     } else {
@@ -837,11 +837,11 @@ void Tab::did_become_active()
     };
 
     BookmarksBarWidget::the().on_bookmark_hover = [this](auto&, auto& url) {
-        m_statusbar->set_text(String::from_deprecated_string(url).release_value_but_fixme_should_propagate_errors());
+        m_statusbar->set_text(String::from_byte_string(url).release_value_but_fixme_should_propagate_errors());
     };
 
     BookmarksBarWidget::the().on_bookmark_change = [this]() {
-        update_bookmark_button(url().to_deprecated_string());
+        update_bookmark_button(url().to_byte_string());
     };
 
     BookmarksBarWidget::the().remove_from_parent();
diff --git a/Userland/Applications/Browser/Tab.h b/Userland/Applications/Browser/Tab.h
index 01edfd54760..eeec0257276 100644
--- a/Userland/Applications/Browser/Tab.h
+++ b/Userland/Applications/Browser/Tab.h
@@ -63,7 +63,7 @@ public:
     void window_position_changed(Gfx::IntPoint);
     void window_size_changed(Gfx::IntSize);
 
-    Function<void(DeprecatedString const&)> on_title_change;
+    Function<void(ByteString const&)> on_title_change;
     Function<void(const URL&)> on_tab_open_request;
     Function<void(Tab&)> on_activate_tab_request;
     Function<void(Tab&)> on_tab_close_request;
@@ -71,8 +71,8 @@ public:
     Function<void(const URL&)> on_window_open_request;
     Function<void(Gfx::Bitmap const&)> on_favicon_change;
     Function<Vector<Web::Cookie::Cookie>(AK::URL const& url)> on_get_all_cookies;
-    Function<Optional<Web::Cookie::Cookie>(AK::URL const& url, DeprecatedString const& name)> on_get_named_cookie;
-    Function<DeprecatedString(const URL&, Web::Cookie::Source source)> on_get_cookie;
+    Function<Optional<Web::Cookie::Cookie>(AK::URL const& url, ByteString const& name)> on_get_named_cookie;
+    Function<ByteString(const URL&, Web::Cookie::Source source)> on_get_cookie;
     Function<void(const URL&, Web::Cookie::ParsedCookie const& cookie, Web::Cookie::Source source)> on_set_cookie;
     Function<void()> on_dump_cookies;
     Function<void(Web::Cookie::Cookie)> on_update_cookie;
@@ -93,7 +93,7 @@ public:
 
     void update_reset_zoom_button();
 
-    DeprecatedString const& title() const { return m_title; }
+    ByteString const& title() const { return m_title; }
     Gfx::Bitmap const* icon() const { return m_icon; }
 
     WebView::OutOfProcessWebView& view() { return *m_web_content_view; }
@@ -111,7 +111,7 @@ private:
     ErrorOr<void> bookmark_current_url();
     void update_bookmark_button(StringView url);
     void start_download(const URL& url);
-    void view_source(const URL& url, DeprecatedString const& source);
+    void view_source(const URL& url, ByteString const& source);
     void update_status(Optional<String> text_override = {}, i32 count_waiting = 0);
     void close_sub_widgets();
 
@@ -160,7 +160,7 @@ private:
     RefPtr<GUI::Menu> m_select_dropdown;
     bool m_select_dropdown_closed_by_action { false };
 
-    DeprecatedString m_title;
+    ByteString m_title;
     RefPtr<Gfx::Bitmap const> m_icon;
 
     Optional<URL> m_navigating_url;
diff --git a/Userland/Applications/Browser/WindowActions.cpp b/Userland/Applications/Browser/WindowActions.cpp
index 5ce96d620e2..94286b47a1d 100644
--- a/Userland/Applications/Browser/WindowActions.cpp
+++ b/Userland/Applications/Browser/WindowActions.cpp
@@ -60,7 +60,7 @@ WindowActions::WindowActions(GUI::Window& window)
 
     for (auto i = 0; i <= 7; ++i) {
         m_tab_actions.append(GUI::Action::create(
-            DeprecatedString::formatted("Tab {}", i + 1), { Mod_Ctrl, static_cast<KeyCode>(Key_1 + i) }, [this, i](auto&) {
+            ByteString::formatted("Tab {}", i + 1), { Mod_Ctrl, static_cast<KeyCode>(Key_1 + i) }, [this, i](auto&) {
                 if (on_tabs[i])
                     on_tabs[i]();
             },
diff --git a/Userland/Applications/Browser/main.cpp b/Userland/Applications/Browser/main.cpp
index f850552dc12..74310675893 100644
--- a/Userland/Applications/Browser/main.cpp
+++ b/Userland/Applications/Browser/main.cpp
@@ -33,17 +33,17 @@
 
 namespace Browser {
 
-DeprecatedString g_search_engine;
-DeprecatedString g_home_url;
-DeprecatedString g_new_tab_url;
+ByteString g_search_engine;
+ByteString g_home_url;
+ByteString g_new_tab_url;
 Vector<String> g_content_filters;
 bool g_content_filters_enabled { true };
 Vector<String> g_autoplay_allowlist;
 bool g_autoplay_allowed_on_all_websites { false };
-Vector<DeprecatedString> g_proxies;
-HashMap<DeprecatedString, size_t> g_proxy_mappings;
+Vector<ByteString> g_proxies;
+HashMap<ByteString, size_t> g_proxy_mappings;
 IconBag g_icon_bag;
-DeprecatedString g_webdriver_content_ipc_path;
+ByteString g_webdriver_content_ipc_path;
 
 }
 
@@ -182,7 +182,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         }
         window->content_filters_changed();
     };
-    TRY(content_filters_watcher->add_watch(DeprecatedString::formatted("{}/BrowserContentFilters.txt", Core::StandardPaths::config_directory()), Core::FileWatcherEvent::Type::ContentModified));
+    TRY(content_filters_watcher->add_watch(ByteString::formatted("{}/BrowserContentFilters.txt", Core::StandardPaths::config_directory()), Core::FileWatcherEvent::Type::ContentModified));
 
     auto autoplay_allowlist_watcher = TRY(Core::FileWatcher::create());
     autoplay_allowlist_watcher->on_change = [&](Core::FileWatcherEvent const&) {
@@ -193,7 +193,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         }
         window->autoplay_allowlist_changed();
     };
-    TRY(autoplay_allowlist_watcher->add_watch(DeprecatedString::formatted("{}/BrowserAutoplayAllowlist.txt", Core::StandardPaths::config_directory()), Core::FileWatcherEvent::Type::ContentModified));
+    TRY(autoplay_allowlist_watcher->add_watch(ByteString::formatted("{}/BrowserAutoplayAllowlist.txt", Core::StandardPaths::config_directory()), Core::FileWatcherEvent::Type::ContentModified));
 
     app->on_action_enter = [&](GUI::Action& action) {
         if (auto* browser_window = dynamic_cast<Browser::BrowserWindow*>(app->active_window())) {
diff --git a/Userland/Applications/BrowserSettings/BrowserSettingsWidget.cpp b/Userland/Applications/BrowserSettings/BrowserSettingsWidget.cpp
index feed66188a9..abba6c51a00 100644
--- a/Userland/Applications/BrowserSettings/BrowserSettingsWidget.cpp
+++ b/Userland/Applications/BrowserSettings/BrowserSettingsWidget.cpp
@@ -15,8 +15,8 @@
 #include <LibWebView/SearchEngine.h>
 
 struct ColorScheme {
-    DeprecatedString title;
-    DeprecatedString setting_value;
+    ByteString title;
+    ByteString setting_value;
 };
 
 class ColorSchemeModel final : public GUI::Model {
@@ -140,8 +140,8 @@ ErrorOr<void> BrowserSettingsWidget::setup()
 
     m_search_engine_combobox->set_model(adopt_ref(*new SearchEngineModel()));
     m_search_engine_combobox->set_only_allow_values_from_model(true);
-    m_search_engine_combobox->on_change = [this](AK::DeprecatedString const&, GUI::ModelIndex const& cursor_index) {
-        auto url_format = m_search_engine_combobox->model()->index(cursor_index.row(), 1).data().to_deprecated_string();
+    m_search_engine_combobox->on_change = [this](AK::ByteString const&, GUI::ModelIndex const& cursor_index) {
+        auto url_format = m_search_engine_combobox->model()->index(cursor_index.row(), 1).data().to_byte_string();
         m_is_custom_search_engine = url_format.is_empty();
         m_custom_search_engine_group->set_enabled(m_is_custom_search_engine);
         set_modified(true);
@@ -159,7 +159,7 @@ void BrowserSettingsWidget::set_color_scheme(StringView color_scheme)
 {
     bool found_color_scheme = false;
     for (int item_index = 0; item_index < m_color_scheme_combobox->model()->row_count(); ++item_index) {
-        auto scheme = m_color_scheme_combobox->model()->index(item_index, 1).data().to_deprecated_string();
+        auto scheme = m_color_scheme_combobox->model()->index(item_index, 1).data().to_byte_string();
         if (scheme == color_scheme) {
             m_color_scheme_combobox->set_selected_index(item_index, GUI::AllowCallback::No);
             found_color_scheme = true;
@@ -183,7 +183,7 @@ void BrowserSettingsWidget::set_search_engine_url(StringView url)
 
         bool found_url = false;
         for (int item_index = 0; item_index < m_search_engine_combobox->model()->row_count(); ++item_index) {
-            auto url_format = m_search_engine_combobox->model()->index(item_index, 1).data().to_deprecated_string();
+            auto url_format = m_search_engine_combobox->model()->index(item_index, 1).data().to_byte_string();
             if (url_format == url) {
                 m_search_engine_combobox->set_selected_index(item_index, GUI::AllowCallback::No);
                 found_url = true;
@@ -226,7 +226,7 @@ void BrowserSettingsWidget::apply_settings()
     Config::write_bool("Browser"sv, "Preferences"sv, "ShowBookmarksBar"sv, m_show_bookmarks_bar_checkbox->is_checked());
 
     auto color_scheme_index = m_color_scheme_combobox->selected_index();
-    auto color_scheme = m_color_scheme_combobox->model()->index(color_scheme_index, 1).data().to_deprecated_string();
+    auto color_scheme = m_color_scheme_combobox->model()->index(color_scheme_index, 1).data().to_byte_string();
     Config::write_string("Browser"sv, "Preferences"sv, "ColorScheme"sv, color_scheme);
 
     if (!m_enable_search_engine_checkbox->is_checked()) {
@@ -235,7 +235,7 @@ void BrowserSettingsWidget::apply_settings()
         Config::write_string("Browser"sv, "Preferences"sv, "SearchEngine"sv, m_custom_search_engine_textbox->text());
     } else {
         auto selected_index = m_search_engine_combobox->selected_index();
-        auto url = m_search_engine_combobox->model()->index(selected_index, 1).data().to_deprecated_string();
+        auto url = m_search_engine_combobox->model()->index(selected_index, 1).data().to_byte_string();
         Config::write_string("Browser"sv, "Preferences"sv, "SearchEngine"sv, url);
     }
 
diff --git a/Userland/Applications/Calculator/CalculatorWidget.cpp b/Userland/Applications/Calculator/CalculatorWidget.cpp
index e10f048ecbe..266f5440fa1 100644
--- a/Userland/Applications/Calculator/CalculatorWidget.cpp
+++ b/Userland/Applications/Calculator/CalculatorWidget.cpp
@@ -130,7 +130,7 @@ void CalculatorWidget::add_digit_button(GUI::Button& button, int digit)
 
 String CalculatorWidget::get_entry()
 {
-    return String::from_deprecated_string(m_entry->text()).release_value_but_fixme_should_propagate_errors();
+    return String::from_byte_string(m_entry->text()).release_value_but_fixme_should_propagate_errors();
 }
 
 void CalculatorWidget::set_entry(Crypto::BigFraction value)
diff --git a/Userland/Applications/Calculator/Keypad.cpp b/Userland/Applications/Calculator/Keypad.cpp
index df1c1b17519..b2291dfa306 100644
--- a/Userland/Applications/Calculator/Keypad.cpp
+++ b/Userland/Applications/Calculator/Keypad.cpp
@@ -124,12 +124,12 @@ void Keypad::set_to_0()
 ErrorOr<String> Keypad::to_string() const
 {
     if (m_state == State::External || m_state == State::TypedExternal)
-        return String::from_deprecated_string(m_internal_value.to_deprecated_string(m_displayed_fraction_length));
+        return String::from_byte_string(m_internal_value.to_byte_string(m_displayed_fraction_length));
 
     StringBuilder builder;
 
-    DeprecatedString const integer_value = m_int_value.to_base_deprecated(10);
-    DeprecatedString const frac_value = m_frac_value.to_base_deprecated(10);
+    ByteString const integer_value = m_int_value.to_base_deprecated(10);
+    ByteString const frac_value = m_frac_value.to_base_deprecated(10);
     unsigned const number_pre_zeros = m_frac_length.to_u64() - (frac_value.length() - 1) - (frac_value == "0" ? 0 : 1);
 
     builder.append(integer_value);
diff --git a/Userland/Applications/Calculator/main.cpp b/Userland/Applications/Calculator/main.cpp
index 870482ebcdb..246ea6acb4b 100644
--- a/Userland/Applications/Calculator/main.cpp
+++ b/Userland/Applications/Calculator/main.cpp
@@ -85,7 +85,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     Optional<unsigned> last_rounding_mode = 1;
     for (unsigned i {}; i < rounding_modes.size(); ++i) {
-        auto round_action = GUI::Action::create_checkable(DeprecatedString::formatted("To &{} Digits", rounding_modes[i]),
+        auto round_action = GUI::Action::create_checkable(ByteString::formatted("To &{} Digits", rounding_modes[i]),
             [&widget, rounding_mode = rounding_modes[i], &last_rounding_mode, i](auto&) {
                 widget->set_rounding_length(rounding_mode);
                 last_rounding_mode = i;
@@ -96,11 +96,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
 
     constexpr auto format { "&Custom - {}..."sv };
-    auto round_custom = GUI::Action::create_checkable(DeprecatedString::formatted(format, 0), [&](auto& action) {
+    auto round_custom = GUI::Action::create_checkable(ByteString::formatted(format, 0), [&](auto& action) {
         int custom_rounding_length = widget->rounding_length();
         auto result = GUI::InputBox::show_numeric(window, custom_rounding_length, 0, 100, "Digits to Round"sv);
         if (!result.is_error() && result.value() == GUI::Dialog::ExecResult::OK) {
-            action.set_text(DeprecatedString::formatted(format, custom_rounding_length));
+            action.set_text(ByteString::formatted(format, custom_rounding_length));
             widget->set_rounding_length(custom_rounding_length);
             last_rounding_mode.clear();
         } else if (last_rounding_mode.has_value())
@@ -115,7 +115,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         auto result = GUI::InputBox::show_numeric(window, shrink_length, 0, 100, "Digits to Shrink"sv);
         if (!result.is_error() && result.value() == GUI::Dialog::ExecResult::OK) {
             round_custom->set_checked(true);
-            round_custom->set_text(DeprecatedString::formatted(format, shrink_length));
+            round_custom->set_text(ByteString::formatted(format, shrink_length));
             widget->set_rounding_length(shrink_length);
             widget->shrink(shrink_length);
         }
diff --git a/Userland/Applications/Calendar/CalendarWidget.cpp b/Userland/Applications/Calendar/CalendarWidget.cpp
index e85616dc78d..20668ebcb4e 100644
--- a/Userland/Applications/Calendar/CalendarWidget.cpp
+++ b/Userland/Applications/Calendar/CalendarWidget.cpp
@@ -123,7 +123,7 @@ void CalendarWidget::load_file(FileSystemAccessClient::File file)
 {
     auto result = m_event_calendar->event_manager().load_file(file);
     if (result.is_error()) {
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Cannot load file: {}", result.error()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Cannot load file: {}", result.error()));
         return;
     }
 
@@ -139,13 +139,13 @@ NonnullRefPtr<GUI::Action> CalendarWidget::create_save_action(GUI::Action& save_
             return;
         }
 
-        auto response = FileSystemAccessClient::Client::the().request_file(window(), current_filename().to_deprecated_string(), Core::File::OpenMode::Write);
+        auto response = FileSystemAccessClient::Client::the().request_file(window(), current_filename().to_byte_string(), Core::File::OpenMode::Write);
         if (response.is_error())
             return;
 
         auto result = m_event_calendar->event_manager().save(response.value());
         if (result.is_error()) {
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Cannot save file: {}", result.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Cannot save file: {}", result.error()));
             return;
         }
 
@@ -163,7 +163,7 @@ NonnullRefPtr<GUI::Action> CalendarWidget::create_save_as_action()
 
         auto result = m_event_calendar->event_manager().save(response.value());
         if (result.is_error()) {
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Cannot save file: {}", result.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Cannot save file: {}", result.error()));
             return;
         }
 
@@ -184,7 +184,7 @@ ErrorOr<NonnullRefPtr<GUI::Action>> CalendarWidget::create_new_calendar_action()
 
         auto result = m_event_calendar->event_manager().save(response.value());
         if (result.is_error()) {
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Cannot save file: {}", result.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Cannot save file: {}", result.error()));
             return;
         }
 
@@ -225,7 +225,7 @@ void CalendarWidget::update_window_title()
         builder.append(current_filename());
     builder.append("[*] - Calendar"sv);
 
-    window()->set_title(builder.to_deprecated_string());
+    window()->set_title(builder.to_byte_string());
 }
 
 ErrorOr<NonnullRefPtr<GUI::Action>> CalendarWidget::create_add_event_action()
diff --git a/Userland/Applications/Calendar/EventCalendar.cpp b/Userland/Applications/Calendar/EventCalendar.cpp
index 5ca66a46b12..807e413ee8b 100644
--- a/Userland/Applications/Calendar/EventCalendar.cpp
+++ b/Userland/Applications/Calendar/EventCalendar.cpp
@@ -36,12 +36,12 @@ void EventCalendar::paint_tile(GUI::Painter& painter, GUI::Calendar::Tile& tile,
             if (!event.has("start_date"sv) || !event.has("start_date"sv) || !event.has("summary"sv))
                 return;
 
-            auto start_date = event.get("start_date"sv).value().to_deprecated_string();
-            auto start_time = event.get("start_time"sv).value().to_deprecated_string();
-            auto summary = event.get("summary"sv).value().to_deprecated_string();
-            auto combined_text = DeprecatedString::formatted("{} {}", start_time, summary);
+            auto start_date = event.get("start_date"sv).value().to_byte_string();
+            auto start_time = event.get("start_time"sv).value().to_byte_string();
+            auto summary = event.get("summary"sv).value().to_byte_string();
+            auto combined_text = ByteString::formatted("{} {}", start_time, summary);
 
-            if (start_date == DeprecatedString::formatted("{}-{:0>2d}-{:0>2d}", tile.year, tile.month, tile.day)) {
+            if (start_date == ByteString::formatted("{}-{:0>2d}-{:0>2d}", tile.year, tile.month, tile.day)) {
 
                 auto text_rect = tile.rect.translated(4, 4 + (font_height + 4) * ++index);
                 painter.draw_text(text_rect, combined_text, Gfx::FontDatabase::default_font(), Gfx::TextAlignment::TopLeft, palette().base_text(), Gfx::TextElision::Right);
diff --git a/Userland/Applications/Calendar/EventManager.cpp b/Userland/Applications/Calendar/EventManager.cpp
index 28c3e0e2867..d0df59103cc 100644
--- a/Userland/Applications/Calendar/EventManager.cpp
+++ b/Userland/Applications/Calendar/EventManager.cpp
@@ -41,7 +41,7 @@ ErrorOr<void> EventManager::save(FileSystemAccessClient::File& file)
     set_dirty(false);
 
     auto stream = file.release_stream();
-    TRY(stream->write_some(m_events.to_deprecated_string().bytes()));
+    TRY(stream->write_some(m_events.to_byte_string().bytes()));
     stream->close();
 
     return {};
diff --git a/Userland/Applications/CertificateSettings/CertificateStoreWidget.cpp b/Userland/Applications/CertificateSettings/CertificateStoreWidget.cpp
index c56b4c300f4..d2c65424893 100644
--- a/Userland/Applications/CertificateSettings/CertificateStoreWidget.cpp
+++ b/Userland/Applications/CertificateSettings/CertificateStoreWidget.cpp
@@ -75,7 +75,7 @@ GUI::Variant CertificateStoreModel::data(GUI::ModelIndex const& index, GUI::Mode
         return issued_by;
     }
     case Column::Expire:
-        return cert.validity.not_after.to_deprecated_string("%Y-%m-%d"sv);
+        return cert.validity.not_after.to_byte_string("%Y-%m-%d"sv);
     default:
         VERIFY_NOT_REACHED();
     }
@@ -141,7 +141,7 @@ ErrorOr<void> CertificateStoreWidget::export_pem()
 
     filename = TRY(filename.replace(" "sv, "_"sv, ReplaceMode::All));
 
-    auto file = FileSystemAccessClient::Client::the().save_file(window(), filename.to_deprecated_string(), "pem"sv);
+    auto file = FileSystemAccessClient::Client::the().save_file(window(), filename.to_byte_string(), "pem"sv);
     if (file.is_error())
         return {};
 
@@ -183,7 +183,7 @@ ErrorOr<void> CertificateStoreWidget::initialize()
     m_import_ca_button->on_click = [&](auto) {
         auto import_result = import_pem();
         if (import_result.is_error()) {
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("{}", import_result.release_error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("{}", import_result.release_error()));
         }
     };
 
@@ -191,7 +191,7 @@ ErrorOr<void> CertificateStoreWidget::initialize()
     m_export_ca_button->on_click = [&](auto) {
         auto export_result = export_pem();
         if (export_result.is_error()) {
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("{}", export_result.release_error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("{}", export_result.release_error()));
         }
     };
 
diff --git a/Userland/Applications/CharacterMap/CharacterMapWidget.cpp b/Userland/Applications/CharacterMap/CharacterMapWidget.cpp
index 2deb1dfb33a..1ae875c36a3 100644
--- a/Userland/Applications/CharacterMap/CharacterMapWidget.cpp
+++ b/Userland/Applications/CharacterMap/CharacterMapWidget.cpp
@@ -54,7 +54,7 @@ CharacterMapWidget::CharacterMapWidget()
                 continue;
             builder.append_code_point(code_point);
         }
-        GUI::Clipboard::the().set_plain_text(builder.to_deprecated_string());
+        GUI::Clipboard::the().set_plain_text(builder.to_byte_string());
     });
     m_copy_selection_action->set_status_tip("Copy the highlighted characters to the clipboard"_string);
 
@@ -139,7 +139,7 @@ CharacterMapWidget::CharacterMapWidget()
     for (auto& block : unicode_blocks)
         m_unicode_block_list.append(block.display_name);
 
-    m_unicode_block_model = GUI::ItemListModel<DeprecatedString>::create(m_unicode_block_list);
+    m_unicode_block_model = GUI::ItemListModel<ByteString>::create(m_unicode_block_list);
     m_unicode_block_listview->set_model(*m_unicode_block_model);
     m_unicode_block_listview->set_activates_on_selection(true);
     m_unicode_block_listview->horizontal_scrollbar().set_visible(false);
diff --git a/Userland/Applications/CharacterMap/CharacterMapWidget.h b/Userland/Applications/CharacterMap/CharacterMapWidget.h
index 562185a86ff..9c2f7bff537 100644
--- a/Userland/Applications/CharacterMap/CharacterMapWidget.h
+++ b/Userland/Applications/CharacterMap/CharacterMapWidget.h
@@ -42,6 +42,6 @@ private:
     RefPtr<GUI::Action> m_go_to_glyph_action;
     RefPtr<GUI::Action> m_find_glyphs_action;
 
-    Vector<DeprecatedString> m_unicode_block_list;
+    Vector<ByteString> m_unicode_block_list;
     Unicode::CodePointRange m_range { 0x0000, 0x10FFFF };
 };
diff --git a/Userland/Applications/CharacterMap/CharacterSearchWidget.cpp b/Userland/Applications/CharacterMap/CharacterSearchWidget.cpp
index 4d6e082a468..1788e364bc0 100644
--- a/Userland/Applications/CharacterMap/CharacterSearchWidget.cpp
+++ b/Userland/Applications/CharacterMap/CharacterSearchWidget.cpp
@@ -12,8 +12,8 @@
 
 struct SearchResult {
     u32 code_point;
-    DeprecatedString code_point_string;
-    DeprecatedString display_text;
+    ByteString code_point_string;
+    ByteString display_text;
 };
 
 class CharacterSearchModel final : public GUI::Model {
@@ -93,7 +93,7 @@ void CharacterSearchWidget::search()
         StringBuilder builder;
         builder.append_code_point(code_point);
 
-        model.add_result({ code_point, builder.to_deprecated_string(), move(display_name) });
+        model.add_result({ code_point, builder.to_byte_string(), move(display_name) });
 
         // Stop when we reach 250 results.
         // This is already too many for the search to be useful, and means we don't spend forever recalculating the column size.
diff --git a/Userland/Applications/CharacterMap/SearchCharacters.cpp b/Userland/Applications/CharacterMap/SearchCharacters.cpp
index ba359cf590a..2e8313cb7cb 100644
--- a/Userland/Applications/CharacterMap/SearchCharacters.cpp
+++ b/Userland/Applications/CharacterMap/SearchCharacters.cpp
@@ -7,9 +7,9 @@
 #include "SearchCharacters.h"
 #include <LibUnicode/CharacterTypes.h>
 
-void for_each_character_containing(StringView query, Function<IterationDecision(u32 code_point, DeprecatedString const& display_name)> callback)
+void for_each_character_containing(StringView query, Function<IterationDecision(u32 code_point, ByteString const& display_name)> callback)
 {
-    DeprecatedString uppercase_query = query.to_uppercase_string();
+    ByteString uppercase_query = query.to_uppercase_string();
     StringView uppercase_query_view = uppercase_query.view();
     constexpr u32 maximum_code_point = 0x10FFFF;
     // FIXME: There's probably a better way to do this than just looping, but it still only takes ~150ms to run for me!
diff --git a/Userland/Applications/CharacterMap/SearchCharacters.h b/Userland/Applications/CharacterMap/SearchCharacters.h
index 209973d453c..51194c115fe 100644
--- a/Userland/Applications/CharacterMap/SearchCharacters.h
+++ b/Userland/Applications/CharacterMap/SearchCharacters.h
@@ -6,8 +6,8 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/IterationDecision.h>
 
-void for_each_character_containing(StringView query, Function<IterationDecision(u32 code_point, DeprecatedString const& display_name)> callback);
+void for_each_character_containing(StringView query, Function<IterationDecision(u32 code_point, ByteString const& display_name)> callback);
diff --git a/Userland/Applications/CharacterMap/main.cpp b/Userland/Applications/CharacterMap/main.cpp
index e64b00947d6..afb939850b1 100644
--- a/Userland/Applications/CharacterMap/main.cpp
+++ b/Userland/Applications/CharacterMap/main.cpp
@@ -17,7 +17,7 @@
 #include <LibGfx/Font/FontDatabase.h>
 #include <LibMain/Main.h>
 
-static void search_and_print_results(DeprecatedString const& query)
+static void search_and_print_results(ByteString const& query)
 {
     outln("Searching for '{}'", query);
     u32 result_count = 0;
@@ -53,7 +53,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::unveil("/res", "r"));
     TRY(Core::System::unveil(nullptr, nullptr));
 
-    DeprecatedString query;
+    ByteString query;
     Core::ArgsParser args_parser;
     args_parser.add_option(query, "Search character names using this query, and print them as a list.", "search", 's', "query");
     args_parser.parse(arguments);
diff --git a/Userland/Applications/ClockSettings/ClockSettingsWidget.h b/Userland/Applications/ClockSettings/ClockSettingsWidget.h
index 227e792b261..df338a350a7 100644
--- a/Userland/Applications/ClockSettings/ClockSettingsWidget.h
+++ b/Userland/Applications/ClockSettings/ClockSettingsWidget.h
@@ -32,5 +32,5 @@ private:
 
     RefPtr<Core::Timer> m_clock_preview_update_timer;
 
-    DeprecatedString m_time_format;
+    ByteString m_time_format;
 };
diff --git a/Userland/Applications/ClockSettings/TimeZoneSettingsWidget.cpp b/Userland/Applications/ClockSettings/TimeZoneSettingsWidget.cpp
index 521145ae949..3eadb11c3f4 100644
--- a/Userland/Applications/ClockSettings/TimeZoneSettingsWidget.cpp
+++ b/Userland/Applications/ClockSettings/TimeZoneSettingsWidget.cpp
@@ -146,7 +146,7 @@ void TimeZoneSettingsWidget::set_time_zone_location()
     auto name = Locale::format_time_zone(locale, m_time_zone, Locale::CalendarPatternStyle::Long, now);
     auto offset = Locale::format_time_zone(locale, m_time_zone, Locale::CalendarPatternStyle::LongOffset, now);
 
-    m_time_zone_text = DeprecatedString::formatted("{}\n({})", name, offset);
+    m_time_zone_text = ByteString::formatted("{}\n({})", name, offset);
 }
 
 // https://en.wikipedia.org/wiki/Mercator_projection#Derivation
diff --git a/Userland/Applications/ClockSettings/TimeZoneSettingsWidget.h b/Userland/Applications/ClockSettings/TimeZoneSettingsWidget.h
index b00c078ca0b..dc7b89f4173 100644
--- a/Userland/Applications/ClockSettings/TimeZoneSettingsWidget.h
+++ b/Userland/Applications/ClockSettings/TimeZoneSettingsWidget.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <AK/RefPtr.h>
 #include <LibGUI/SettingsWindow.h>
@@ -30,11 +30,11 @@ private:
     Optional<Gfx::FloatPoint> compute_time_zone_location() const;
     void set_time_zone();
 
-    DeprecatedString m_time_zone;
+    ByteString m_time_zone;
     RefPtr<GUI::ComboBox> m_time_zone_combo_box;
     RefPtr<GUI::ImageWidget> m_time_zone_map;
     RefPtr<Gfx::Bitmap> m_time_zone_marker;
 
     Optional<Gfx::FloatPoint> m_time_zone_location;
-    DeprecatedString m_time_zone_text;
+    ByteString m_time_zone_text;
 };
diff --git a/Userland/Applications/CrashReporter/main.cpp b/Userland/Applications/CrashReporter/main.cpp
index eded509c6ca..78a3746e93a 100644
--- a/Userland/Applications/CrashReporter/main.cpp
+++ b/Userland/Applications/CrashReporter/main.cpp
@@ -44,8 +44,8 @@
 #include <unistd.h>
 
 struct TitleAndText {
-    DeprecatedString title;
-    DeprecatedString text;
+    ByteString title;
+    ByteString text;
 };
 
 struct ThreadBacktracesAndCpuRegisters {
@@ -104,17 +104,17 @@ static TitleAndText build_backtrace(Coredump::Reader const& coredump, ELF::Core:
             first_entry = false;
         else
             builder.append('\n');
-        builder.append(entry.to_deprecated_string());
+        builder.append(entry.to_byte_string());
     }
 
     dbgln("--- Backtrace for thread #{} (TID {}) ---", thread_index, thread_info.tid);
     for (auto& entry : backtrace.entries()) {
-        dbgln("{}", entry.to_deprecated_string(true));
+        dbgln("{}", entry.to_byte_string(true));
     }
 
     return {
-        DeprecatedString::formatted("Thread #{} (TID {})", thread_index, thread_info.tid),
-        builder.to_deprecated_string()
+        ByteString::formatted("Thread #{} (TID {})", thread_index, thread_info.tid),
+        builder.to_byte_string()
     };
 }
 
@@ -151,8 +151,8 @@ static TitleAndText build_cpu_registers(const ELF::Core::ThreadInfo& thread_info
 #endif
 
     return {
-        DeprecatedString::formatted("Thread #{} (TID {})", thread_index, thread_info.tid),
-        builder.to_deprecated_string()
+        ByteString::formatted("Thread #{} (TID {})", thread_index, thread_info.tid),
+        builder.to_byte_string()
     };
 }
 
@@ -168,7 +168,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto app = TRY(GUI::Application::create(arguments));
 
-    DeprecatedString coredump_path {};
+    ByteString coredump_path {};
     bool unlink_on_exit = false;
     StringBuilder full_backtrace;
 
@@ -184,9 +184,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return 1;
     }
 
-    Vector<DeprecatedString> memory_regions;
+    Vector<ByteString> memory_regions;
     coredump->for_each_memory_region_info([&](auto& memory_region_info) {
-        memory_regions.append(DeprecatedString::formatted("{:p} - {:p}: {}", memory_region_info.region_start, memory_region_info.region_end, memory_region_info.region_name));
+        memory_regions.append(ByteString::formatted("{:p} - {:p}: {}", memory_region_info.region_start, memory_region_info.region_end, memory_region_info.region_name));
         return IterationDecision::Continue;
     });
 
@@ -223,14 +223,14 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     description_label.set_text(TRY(String::formatted("\"{}\" (PID {}) has crashed - {} (signal {})", app_name, pid, strsignal(termination_signal), termination_signal)));
 
     auto& executable_link_label = *widget->find_descendant_of_type_named<GUI::LinkLabel>("executable_link");
-    executable_link_label.set_text(TRY(String::from_deprecated_string(LexicalPath::canonicalized_path(executable_path))));
+    executable_link_label.set_text(TRY(String::from_byte_string(LexicalPath::canonicalized_path(executable_path))));
     executable_link_label.on_click = [&] {
         LexicalPath path { executable_path };
         Desktop::Launcher::open(URL::create_with_file_scheme(path.dirname(), path.basename()));
     };
 
     auto& coredump_link_label = *widget->find_descendant_of_type_named<GUI::LinkLabel>("coredump_link");
-    coredump_link_label.set_text(TRY(String::from_deprecated_string(LexicalPath::canonicalized_path(coredump_path))));
+    coredump_link_label.set_text(TRY(String::from_byte_string(LexicalPath::canonicalized_path(coredump_path))));
     coredump_link_label.on_click = [&] {
         LexicalPath path { coredump_path };
         Desktop::Launcher::open(URL::create_with_file_scheme(path.dirname(), path.basename()));
@@ -266,7 +266,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     environment_tab.set_layout<GUI::VerticalBoxLayout>(4);
 
     auto& environment_text_editor = environment_tab.add<GUI::TextEditor>();
-    environment_text_editor.set_text(DeprecatedString::join('\n', environment));
+    environment_text_editor.set_text(ByteString::join('\n', environment));
     environment_text_editor.set_mode(GUI::TextEditor::Mode::ReadOnly);
     environment_text_editor.set_wrapping_mode(GUI::TextEditor::WrappingMode::NoWrap);
     environment_text_editor.set_should_hide_unnecessary_scrollbars(true);
@@ -275,7 +275,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     memory_regions_tab.set_layout<GUI::VerticalBoxLayout>(4);
 
     auto& memory_regions_text_editor = memory_regions_tab.add<GUI::TextEditor>();
-    memory_regions_text_editor.set_text(DeprecatedString::join('\n', memory_regions));
+    memory_regions_text_editor.set_text(ByteString::join('\n', memory_regions));
     memory_regions_text_editor.set_mode(GUI::TextEditor::Mode::ReadOnly);
     memory_regions_text_editor.set_wrapping_mode(GUI::TextEditor::WrappingMode::NoWrap);
     memory_regions_text_editor.set_should_hide_unnecessary_scrollbars(true);
@@ -296,23 +296,23 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto& save_backtrace_button = *widget->find_descendant_of_type_named<GUI::Button>("save_backtrace_button");
     save_backtrace_button.set_icon(TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/save.png"sv)));
     save_backtrace_button.on_click = [&](auto) {
-        LexicalPath lexical_path(DeprecatedString::formatted("{}_{}_backtrace.txt", pid, app_name));
+        LexicalPath lexical_path(ByteString::formatted("{}_{}_backtrace.txt", pid, app_name));
         auto file_or_error = FileSystemAccessClient::Client::the().save_file(window, lexical_path.title(), lexical_path.extension());
         if (file_or_error.is_error()) {
-            GUI::MessageBox::show(window, DeprecatedString::formatted("Communication failed with FileSystemAccessServer: {}.", file_or_error.release_error()), "Saving backtrace failed"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(window, ByteString::formatted("Communication failed with FileSystemAccessServer: {}.", file_or_error.release_error()), "Saving backtrace failed"sv, GUI::MessageBox::Type::Error);
             return;
         }
         auto file = file_or_error.release_value().release_stream();
 
         auto byte_buffer_or_error = full_backtrace.to_byte_buffer();
         if (byte_buffer_or_error.is_error()) {
-            GUI::MessageBox::show(window, DeprecatedString::formatted("Couldn't create backtrace: {}.", byte_buffer_or_error.release_error()), "Saving backtrace failed"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(window, ByteString::formatted("Couldn't create backtrace: {}.", byte_buffer_or_error.release_error()), "Saving backtrace failed"sv, GUI::MessageBox::Type::Error);
             return;
         }
         auto byte_buffer = byte_buffer_or_error.release_value();
 
         if (auto result = file->write_until_depleted(byte_buffer); result.is_error())
-            GUI::MessageBox::show(window, DeprecatedString::formatted("Couldn't save file: {}.", result.release_error()), "Saving backtrace failed"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(window, ByteString::formatted("Couldn't save file: {}.", result.release_error()), "Saving backtrace failed"sv, GUI::MessageBox::Type::Error);
     };
     save_backtrace_button.set_enabled(false);
 
@@ -336,7 +336,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         },
         [&](auto results) -> ErrorOr<void> {
             for (auto& backtrace : results.thread_backtraces) {
-                auto& container = backtrace_tab_widget.add_tab<GUI::Widget>(TRY(String::from_deprecated_string(backtrace.title)));
+                auto& container = backtrace_tab_widget.add_tab<GUI::Widget>(TRY(String::from_byte_string(backtrace.title)));
                 container.template set_layout<GUI::VerticalBoxLayout>(4);
                 auto& backtrace_text_editor = container.template add<GUI::TextEditor>();
                 backtrace_text_editor.set_text(backtrace.text);
@@ -347,7 +347,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             }
 
             for (auto& cpu_registers : results.thread_cpu_registers) {
-                auto& container = cpu_registers_tab_widget.add_tab<GUI::Widget>(TRY(String::from_deprecated_string(cpu_registers.title)));
+                auto& container = cpu_registers_tab_widget.add_tab<GUI::Widget>(TRY(String::from_byte_string(cpu_registers.title)));
                 container.template set_layout<GUI::VerticalBoxLayout>(4);
                 auto& cpu_registers_text_editor = container.template add<GUI::TextEditor>();
                 cpu_registers_text_editor.set_text(cpu_registers.text);
diff --git a/Userland/Applications/Debugger/main.cpp b/Userland/Applications/Debugger/main.cpp
index 1791f343720..20c6e802d3e 100644
--- a/Userland/Applications/Debugger/main.cpp
+++ b/Userland/Applications/Debugger/main.cpp
@@ -56,7 +56,7 @@ static void handle_print_registers(PtraceRegisters const& regs)
 #endif
 }
 
-static bool handle_disassemble_command(DeprecatedString const& command, FlatPtr first_instruction)
+static bool handle_disassemble_command(ByteString const& command, FlatPtr first_instruction)
 {
     auto parts = command.split(' ');
     size_t number_of_instructions_to_disassemble = 5;
@@ -88,7 +88,7 @@ static bool handle_disassemble_command(DeprecatedString const& command, FlatPtr
         if (!insn.has_value())
             break;
 
-        outln("    {:p} <+{}>:\t{}", offset + first_instruction, offset, insn.value().to_deprecated_string(offset));
+        outln("    {:p} <+{}>:\t{}", offset + first_instruction, offset, insn.value().to_byte_string(offset));
     }
 
     return true;
@@ -106,7 +106,7 @@ static bool insert_breakpoint_at_address(FlatPtr address)
     return g_debug_session->insert_breakpoint(address);
 }
 
-static bool insert_breakpoint_at_source_position(DeprecatedString const& file, size_t line)
+static bool insert_breakpoint_at_source_position(ByteString const& file, size_t line)
 {
     auto result = g_debug_session->insert_breakpoint(file, line);
     if (!result.has_value()) {
@@ -117,7 +117,7 @@ static bool insert_breakpoint_at_source_position(DeprecatedString const& file, s
     return true;
 }
 
-static bool insert_breakpoint_at_symbol(DeprecatedString const& symbol)
+static bool insert_breakpoint_at_symbol(ByteString const& symbol)
 {
     auto result = g_debug_session->insert_breakpoint(symbol);
     if (!result.has_value()) {
@@ -128,7 +128,7 @@ static bool insert_breakpoint_at_symbol(DeprecatedString const& symbol)
     return true;
 }
 
-static bool handle_breakpoint_command(DeprecatedString const& command)
+static bool handle_breakpoint_command(ByteString const& command)
 {
     auto parts = command.split(' ');
     if (parts.size() != 2)
@@ -155,7 +155,7 @@ static bool handle_breakpoint_command(DeprecatedString const& command)
     return insert_breakpoint_at_symbol(argument);
 }
 
-static bool handle_examine_command(DeprecatedString const& command)
+static bool handle_examine_command(ByteString const& command)
 {
     auto parts = command.split(' ');
     if (parts.size() != 2)
diff --git a/Userland/Applications/DisplaySettings/BackgroundSettingsWidget.cpp b/Userland/Applications/DisplaySettings/BackgroundSettingsWidget.cpp
index 115e28e9454..44f375a46ef 100644
--- a/Userland/Applications/DisplaySettings/BackgroundSettingsWidget.cpp
+++ b/Userland/Applications/DisplaySettings/BackgroundSettingsWidget.cpp
@@ -63,7 +63,7 @@ ErrorOr<void> BackgroundSettingsWidget::create_frame()
         String path;
         if (!m_wallpaper_view->selection().is_empty()) {
             auto index = m_wallpaper_view->selection().first();
-            auto path_or_error = String::from_deprecated_string(static_cast<GUI::FileSystemModel*>(m_wallpaper_view->model())->full_path(index));
+            auto path_or_error = String::from_byte_string(static_cast<GUI::FileSystemModel*>(m_wallpaper_view->model())->full_path(index));
             if (path_or_error.is_error()) {
                 GUI::MessageBox::show_error(window(), "Unable to load wallpaper"sv);
                 return;
@@ -78,7 +78,7 @@ ErrorOr<void> BackgroundSettingsWidget::create_frame()
     m_context_menu = GUI::Menu::construct();
     auto const file_manager_icon = TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/app-file-manager.png"sv));
     m_show_in_file_manager_action = GUI::Action::create("Show in File Manager", file_manager_icon, [this](GUI::Action const&) {
-        LexicalPath path { m_monitor_widget->wallpaper().value().to_deprecated_string() };
+        LexicalPath path { m_monitor_widget->wallpaper().value().to_byte_string() };
         Desktop::Launcher::open(URL::create_with_file_scheme(path.dirname(), path.basename()));
     });
     m_context_menu->add_action(*m_show_in_file_manager_action);
@@ -88,7 +88,7 @@ ErrorOr<void> BackgroundSettingsWidget::create_frame()
         [this](auto&) {
             auto wallpaper = m_monitor_widget->wallpaper();
             if (wallpaper.has_value())
-                GUI::Clipboard::the().set_data(URL::create_with_file_scheme(wallpaper.value().to_deprecated_string()).to_deprecated_string().bytes(), "text/uri-list");
+                GUI::Clipboard::the().set_data(URL::create_with_file_scheme(wallpaper.value().to_byte_string()).to_byte_string().bytes(), "text/uri-list");
         },
         this);
     m_context_menu->add_action(*m_copy_action);
@@ -144,14 +144,14 @@ ErrorOr<void> BackgroundSettingsWidget::load_current_settings()
 {
     auto ws_config = TRY(Core::ConfigFile::open("/etc/WindowServer.ini"));
 
-    auto selected_wallpaper = TRY(String::from_deprecated_string(Config::read_string("WindowManager"sv, "Background"sv, "Wallpaper"sv, ""sv)));
+    auto selected_wallpaper = TRY(String::from_byte_string(Config::read_string("WindowManager"sv, "Background"sv, "Wallpaper"sv, ""sv)));
     if (!selected_wallpaper.is_empty()) {
-        auto index = static_cast<GUI::FileSystemModel*>(m_wallpaper_view->model())->index(selected_wallpaper.to_deprecated_string(), m_wallpaper_view->model_column());
+        auto index = static_cast<GUI::FileSystemModel*>(m_wallpaper_view->model())->index(selected_wallpaper.to_byte_string(), m_wallpaper_view->model_column());
         m_wallpaper_view->set_cursor(index, GUI::AbstractView::SelectionUpdate::Set);
         m_monitor_widget->set_wallpaper(selected_wallpaper);
     }
 
-    auto mode = TRY(String::from_deprecated_string(ws_config->read_entry("Background", "Mode", "Center")));
+    auto mode = TRY(String::from_byte_string(ws_config->read_entry("Background", "Mode", "Center")));
     if (!m_modes.contains_slow(mode)) {
         warnln("Invalid background mode '{}' in WindowServer config, falling back to 'Center'", mode);
         mode = "Center"_string;
diff --git a/Userland/Applications/DisplaySettings/FontSettingsWidget.cpp b/Userland/Applications/DisplaySettings/FontSettingsWidget.cpp
index 2bc6d39cb2e..b26b3414c97 100644
--- a/Userland/Applications/DisplaySettings/FontSettingsWidget.cpp
+++ b/Userland/Applications/DisplaySettings/FontSettingsWidget.cpp
@@ -79,9 +79,9 @@ static void update_label_with_font(GUI::Label& label, Gfx::Font const& font)
 void FontSettingsWidget::apply_settings()
 {
     GUI::ConnectionToWindowServer::the().set_system_fonts(
-        m_default_font_label->font().qualified_name().to_deprecated_string(),
-        m_fixed_width_font_label->font().qualified_name().to_deprecated_string(),
-        m_window_title_font_label->font().qualified_name().to_deprecated_string());
+        m_default_font_label->font().qualified_name().to_byte_string(),
+        m_fixed_width_font_label->font().qualified_name().to_byte_string(),
+        m_window_title_font_label->font().qualified_name().to_byte_string());
 }
 
 }
diff --git a/Userland/Applications/DisplaySettings/MonitorSettingsWidget.cpp b/Userland/Applications/DisplaySettings/MonitorSettingsWidget.cpp
index 39b2c52438f..30b57eb2a24 100644
--- a/Userland/Applications/DisplaySettings/MonitorSettingsWidget.cpp
+++ b/Userland/Applications/DisplaySettings/MonitorSettingsWidget.cpp
@@ -142,7 +142,7 @@ static ErrorOr<String> display_name_from_edid(EDID::Parser const& edid)
 
     auto build_manufacturer_product_name = [&]() -> ErrorOr<String> {
         if (product_name.is_empty())
-            return TRY(String::from_deprecated_string(manufacturer_name));
+            return TRY(String::from_byte_string(manufacturer_name));
         return String::formatted("{} {}", manufacturer_name, product_name);
     };
 
@@ -170,7 +170,7 @@ ErrorOr<void> MonitorSettingsWidget::load_current_settings()
                 TRY(m_screen_edids.try_append(edid.release_value()));
             } else {
                 dbgln("Error getting EDID from device {}: {}", m_screen_layout.screens[i].device.value(), edid.error());
-                screen_display_name = TRY(String::from_deprecated_string(m_screen_layout.screens[i].device.value()));
+                screen_display_name = TRY(String::from_byte_string(m_screen_layout.screens[i].device.value()));
                 TRY(m_screen_edids.try_append({}));
             }
         } else {
diff --git a/Userland/Applications/DisplaySettings/ThemePreviewWidget.cpp b/Userland/Applications/DisplaySettings/ThemePreviewWidget.cpp
index 4adc8d06313..d65d5d1e855 100644
--- a/Userland/Applications/DisplaySettings/ThemePreviewWidget.cpp
+++ b/Userland/Applications/DisplaySettings/ThemePreviewWidget.cpp
@@ -20,8 +20,8 @@ ThemePreviewWidget::ThemePreviewWidget(Gfx::Palette const& palette)
 
 ErrorOr<void> ThemePreviewWidget::set_theme(String path)
 {
-    auto config_file = TRY(Core::File::open(path.to_deprecated_string(), Core::File::OpenMode::Read));
-    TRY(set_theme_from_file(path.to_deprecated_string(), move(config_file)));
+    auto config_file = TRY(Core::File::open(path.to_byte_string(), Core::File::OpenMode::Read));
+    TRY(set_theme_from_file(path.to_byte_string(), move(config_file)));
     return {};
 }
 
diff --git a/Userland/Applications/DisplaySettings/ThemesSettingsWidget.cpp b/Userland/Applications/DisplaySettings/ThemesSettingsWidget.cpp
index 36ec4cb92ba..682d4f1aae3 100644
--- a/Userland/Applications/DisplaySettings/ThemesSettingsWidget.cpp
+++ b/Userland/Applications/DisplaySettings/ThemesSettingsWidget.cpp
@@ -20,7 +20,7 @@ namespace DisplaySettings {
 
 static ErrorOr<String> get_color_scheme_name_from_pathname(StringView color_scheme_path)
 {
-    return TRY(String::from_deprecated_string(color_scheme_path.replace("/res/color-schemes/"sv, ""sv, ReplaceMode::FirstOnly).replace(".ini"sv, ""sv, ReplaceMode::FirstOnly)));
+    return TRY(String::from_byte_string(color_scheme_path.replace("/res/color-schemes/"sv, ""sv, ReplaceMode::FirstOnly).replace(".ini"sv, ""sv, ReplaceMode::FirstOnly)));
 }
 
 ErrorOr<NonnullRefPtr<ThemesSettingsWidget>> ThemesSettingsWidget::try_create(bool& background_settings_changed)
@@ -40,7 +40,7 @@ ErrorOr<void> ThemesSettingsWidget::setup_interface()
     auto current_theme_name = GUI::ConnectionToWindowServer::the().get_system_theme();
     TRY(m_theme_names.try_ensure_capacity(m_themes.size()));
     for (auto& theme_meta : m_themes) {
-        TRY(m_theme_names.try_append(TRY(String::from_deprecated_string(theme_meta.name))));
+        TRY(m_theme_names.try_append(TRY(String::from_byte_string(theme_meta.name))));
         if (current_theme_name == theme_meta.name) {
             m_selected_theme = &theme_meta;
             current_theme_index = m_theme_names.size() - 1;
@@ -53,7 +53,7 @@ ErrorOr<void> ThemesSettingsWidget::setup_interface()
     m_themes_combo->set_model(*GUI::ItemListModel<String>::create(m_theme_names));
     m_themes_combo->on_change = [this](auto&, const GUI::ModelIndex& index) {
         m_selected_theme = &m_themes.at(index.row());
-        auto selected_theme_path = String::from_deprecated_string(m_selected_theme->path);
+        auto selected_theme_path = String::from_byte_string(m_selected_theme->path);
         ErrorOr<void> set_theme_result;
         if (!selected_theme_path.is_error())
             set_theme_result = m_theme_preview->set_theme(selected_theme_path.release_value());
@@ -98,7 +98,7 @@ ErrorOr<void> ThemesSettingsWidget::setup_interface()
         }
     }
     color_scheme_combo.on_change = [this](auto&, const GUI::ModelIndex& index) {
-        auto result = String::from_deprecated_string(index.data().as_string());
+        auto result = String::from_byte_string(index.data().as_string());
         if (result.is_error())
             return;
         m_selected_color_scheme_name = result.release_value();
@@ -139,7 +139,7 @@ ErrorOr<void> ThemesSettingsWidget::setup_interface()
             if (current_theme_name == theme_meta.name) {
                 m_themes_combo->set_selected_index(index, GUI::AllowCallback::No);
                 m_selected_theme = &m_themes.at(index);
-                auto selected_theme_path = String::from_deprecated_string(m_selected_theme->path);
+                auto selected_theme_path = String::from_byte_string(m_selected_theme->path);
                 ErrorOr<void> set_theme_result;
                 if (!selected_theme_path.is_error())
                     set_theme_result = m_theme_preview->set_theme(selected_theme_path.release_value());
@@ -178,7 +178,7 @@ void ThemesSettingsWidget::apply_settings()
         if (!set_theme_result)
             GUI::MessageBox::show_error(window(), "Failed to apply theme settings"sv);
     } else if (find_descendant_of_type_named<GUI::CheckBox>("custom_color_scheme_checkbox")->is_checked()) {
-        auto set_theme_result = GUI::ConnectionToWindowServer::the().set_system_theme(m_selected_theme->path, m_selected_theme->name, m_background_settings_changed, color_scheme_path.to_deprecated_string());
+        auto set_theme_result = GUI::ConnectionToWindowServer::the().set_system_theme(m_selected_theme->path, m_selected_theme->name, m_background_settings_changed, color_scheme_path.to_byte_string());
         if (!set_theme_result)
             GUI::MessageBox::show_error(window(), "Failed to apply theme settings"sv);
     } else {
diff --git a/Userland/Applications/Escalator/EscalatorWindow.cpp b/Userland/Applications/Escalator/EscalatorWindow.cpp
index 78732fb13f1..000bfba8a2b 100644
--- a/Userland/Applications/Escalator/EscalatorWindow.cpp
+++ b/Userland/Applications/Escalator/EscalatorWindow.cpp
@@ -56,7 +56,7 @@ EscalatorWindow::EscalatorWindow(StringView executable, Vector<StringView> argum
     m_ok_button->on_click = [this](auto) {
         auto result = check_password();
         if (result.is_error()) {
-            GUI::MessageBox::show_error(this, DeprecatedString::formatted("Failed to execute command: {}", result.error()));
+            GUI::MessageBox::show_error(this, ByteString::formatted("Failed to execute command: {}", result.error()));
         }
         close();
     };
@@ -72,7 +72,7 @@ EscalatorWindow::EscalatorWindow(StringView executable, Vector<StringView> argum
 
 ErrorOr<void> EscalatorWindow::check_password()
 {
-    DeprecatedString password = m_password_input->text();
+    ByteString password = m_password_input->text();
     if (password.is_empty()) {
         GUI::MessageBox::show_error(this, "Please enter a password."sv);
         return {};
diff --git a/Userland/Applications/Escalator/main.cpp b/Userland/Applications/Escalator/main.cpp
index 6b238073a0b..019ba1dea2a 100644
--- a/Userland/Applications/Escalator/main.cpp
+++ b/Userland/Applications/Escalator/main.cpp
@@ -7,7 +7,7 @@
  */
 
 #include "EscalatorWindow.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/Account.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/System.h>
@@ -39,7 +39,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto executable_path = Core::System::resolve_executable_from_environment(command[0], AT_EACCESS);
     if (executable_path.is_error()) {
-        GUI::MessageBox::show_error(nullptr, DeprecatedString::formatted("Could not execute command {}: Command not found.", command[0]));
+        GUI::MessageBox::show_error(nullptr, ByteString::formatted("Could not execute command {}: Command not found.", command[0]));
         return 127;
     }
 
diff --git a/Userland/Applications/FileManager/DirectoryView.cpp b/Userland/Applications/FileManager/DirectoryView.cpp
index 2c848c79101..7447e62d211 100644
--- a/Userland/Applications/FileManager/DirectoryView.cpp
+++ b/Userland/Applications/FileManager/DirectoryView.cpp
@@ -76,7 +76,7 @@ Vector<NonnullRefPtr<LauncherHandler>> DirectoryView::get_launch_handlers(URL co
     return handlers;
 }
 
-Vector<NonnullRefPtr<LauncherHandler>> DirectoryView::get_launch_handlers(DeprecatedString const& path)
+Vector<NonnullRefPtr<LauncherHandler>> DirectoryView::get_launch_handlers(ByteString const& path)
 {
     return get_launch_handlers(URL::create_with_file_scheme(path));
 }
@@ -92,7 +92,7 @@ void DirectoryView::handle_activation(GUI::ModelIndex const& index)
     struct stat st;
     if (stat(path.characters(), &st) < 0) {
         perror("stat");
-        auto error_message = DeprecatedString::formatted("Could not stat {}: {}", path, strerror(errno));
+        auto error_message = ByteString::formatted("Could not stat {}: {}", path, strerror(errno));
         GUI::MessageBox::show(window(), error_message, "File Manager"sv, GUI::MessageBox::Type::Error);
         return;
     }
@@ -112,11 +112,11 @@ void DirectoryView::handle_activation(GUI::ModelIndex const& index)
 
     if (default_launcher) {
         auto launch_origin_rect = current_view().to_widget_rect(current_view().content_rect(index)).translated(current_view().screen_relative_rect().location());
-        setenv("__libgui_launch_origin_rect", DeprecatedString::formatted("{},{},{},{}", launch_origin_rect.x(), launch_origin_rect.y(), launch_origin_rect.width(), launch_origin_rect.height()).characters(), 1);
+        setenv("__libgui_launch_origin_rect", ByteString::formatted("{},{},{},{}", launch_origin_rect.x(), launch_origin_rect.y(), launch_origin_rect.width(), launch_origin_rect.height()).characters(), 1);
         launch(url, *default_launcher);
         unsetenv("__libgui_launch_origin_rect");
     } else {
-        auto error_message = DeprecatedString::formatted("Could not open {}", path);
+        auto error_message = ByteString::formatted("Could not open {}", path);
         GUI::MessageBox::show(window(), error_message, "File Manager"sv, GUI::MessageBox::Type::Error);
     }
 }
@@ -168,7 +168,7 @@ void DirectoryView::setup_model()
     };
 
     m_model->on_rename_error = [this](int, char const* error_string) {
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Unable to rename file: {}", error_string));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Unable to rename file: {}", error_string));
     };
 
     m_model->on_complete = [this] {
@@ -340,7 +340,7 @@ void DirectoryView::model_did_update(unsigned flags)
     update_statusbar();
 }
 
-void DirectoryView::set_view_mode_from_string(DeprecatedString const& mode)
+void DirectoryView::set_view_mode_from_string(ByteString const& mode)
 {
     if (m_mode == Mode::Desktop)
         return;
@@ -389,7 +389,7 @@ void DirectoryView::set_view_mode(ViewMode mode)
     VERIFY_NOT_REACHED();
 }
 
-void DirectoryView::add_path_to_history(DeprecatedString path)
+void DirectoryView::add_path_to_history(ByteString path)
 {
     if (m_path_history.size() && m_path_history.at(m_path_history_position) == path)
         return;
@@ -401,7 +401,7 @@ void DirectoryView::add_path_to_history(DeprecatedString path)
     m_path_history_position = m_path_history.size() - 1;
 }
 
-bool DirectoryView::open(DeprecatedString const& path)
+bool DirectoryView::open(ByteString const& path)
 {
     auto error_or_real_path = FileSystem::real_path(path);
     if (error_or_real_path.is_error() || !FileSystem::is_directory(path))
@@ -413,11 +413,11 @@ bool DirectoryView::open(DeprecatedString const& path)
         warnln("Failed to open '{}': {}", real_path, result.error());
     }
 
-    if (model().root_path() == real_path.to_deprecated_string()) {
+    if (model().root_path() == real_path.to_byte_string()) {
         refresh();
     } else {
         set_active_widget(&current_view());
-        model().set_root_path(real_path.to_deprecated_string());
+        model().set_root_path(real_path.to_byte_string());
     }
     return true;
 }
@@ -528,15 +528,15 @@ void DirectoryView::launch(URL const&, LauncherHandler const& launcher_handler)
     }
 }
 
-Vector<DeprecatedString> DirectoryView::selected_file_paths() const
+Vector<ByteString> DirectoryView::selected_file_paths() const
 {
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
     auto& view = current_view();
     auto& model = *view.model();
     view.selection().for_each_index([&](GUI::ModelIndex const& index) {
         auto parent_index = model.parent_index(index);
         auto name_index = model.index(index.row(), GUI::FileSystemModel::Column::Name, parent_index);
-        auto path = name_index.data(GUI::ModelRole::Custom).to_deprecated_string();
+        auto path = name_index.data(GUI::ModelRole::Custom).to_byte_string();
         paths.append(path);
     });
     return paths;
@@ -580,11 +580,11 @@ void DirectoryView::setup_actions()
         String value;
         auto icon = Gfx::Bitmap::load_from_file("/res/icons/32x32/filetype-folder.png"sv).release_value_but_fixme_should_propagate_errors();
         if (GUI::InputBox::show(window(), value, "Enter a name:"sv, "New Directory"sv, GUI::InputType::NonemptyText, {}, move(icon)) == GUI::InputBox::ExecResult::OK) {
-            auto new_dir_path = LexicalPath::canonicalized_path(DeprecatedString::formatted("{}/{}", path(), value));
+            auto new_dir_path = LexicalPath::canonicalized_path(ByteString::formatted("{}/{}", path(), value));
             int rc = mkdir(new_dir_path.characters(), 0777);
             if (rc < 0) {
                 auto saved_errno = errno;
-                GUI::MessageBox::show(window(), DeprecatedString::formatted("mkdir(\"{}\") failed: {}", new_dir_path, strerror(saved_errno)), "Error"sv, GUI::MessageBox::Type::Error);
+                GUI::MessageBox::show(window(), ByteString::formatted("mkdir(\"{}\") failed: {}", new_dir_path, strerror(saved_errno)), "Error"sv, GUI::MessageBox::Type::Error);
             }
         }
     });
@@ -593,22 +593,22 @@ void DirectoryView::setup_actions()
         String value;
         auto icon = Gfx::Bitmap::load_from_file("/res/icons/32x32/filetype-unknown.png"sv).release_value_but_fixme_should_propagate_errors();
         if (GUI::InputBox::show(window(), value, "Enter a name:"sv, "New File"sv, GUI::InputType::NonemptyText, {}, move(icon)) == GUI::InputBox::ExecResult::OK) {
-            auto new_file_path = LexicalPath::canonicalized_path(DeprecatedString::formatted("{}/{}", path(), value));
+            auto new_file_path = LexicalPath::canonicalized_path(ByteString::formatted("{}/{}", path(), value));
             struct stat st;
             int rc = stat(new_file_path.characters(), &st);
             if ((rc < 0 && errno != ENOENT)) {
                 auto saved_errno = errno;
-                GUI::MessageBox::show(window(), DeprecatedString::formatted("stat(\"{}\") failed: {}", new_file_path, strerror(saved_errno)), "Error"sv, GUI::MessageBox::Type::Error);
+                GUI::MessageBox::show(window(), ByteString::formatted("stat(\"{}\") failed: {}", new_file_path, strerror(saved_errno)), "Error"sv, GUI::MessageBox::Type::Error);
                 return;
             }
             if (rc == 0) {
-                GUI::MessageBox::show(window(), DeprecatedString::formatted("{}: Already exists", new_file_path), "Error"sv, GUI::MessageBox::Type::Error);
+                GUI::MessageBox::show(window(), ByteString::formatted("{}: Already exists", new_file_path), "Error"sv, GUI::MessageBox::Type::Error);
                 return;
             }
             int fd = creat(new_file_path.characters(), 0666);
             if (fd < 0) {
                 auto saved_errno = errno;
-                GUI::MessageBox::show(window(), DeprecatedString::formatted("creat(\"{}\") failed: {}", new_file_path, strerror(saved_errno)), "Error"sv, GUI::MessageBox::Type::Error);
+                GUI::MessageBox::show(window(), ByteString::formatted("creat(\"{}\") failed: {}", new_file_path, strerror(saved_errno)), "Error"sv, GUI::MessageBox::Type::Error);
                 return;
             }
             rc = close(fd);
diff --git a/Userland/Applications/FileManager/DirectoryView.h b/Userland/Applications/FileManager/DirectoryView.h
index 281c678f762..3ef39a48000 100644
--- a/Userland/Applications/FileManager/DirectoryView.h
+++ b/Userland/Applications/FileManager/DirectoryView.h
@@ -51,8 +51,8 @@ public:
 
     virtual ~DirectoryView() override;
 
-    bool open(DeprecatedString const& path);
-    DeprecatedString path() const { return model().root_path(); }
+    bool open(ByteString const& path);
+    ByteString path() const { return model().root_path(); }
     void open_parent_directory();
     void open_previous_directory();
     void open_next_directory();
@@ -60,7 +60,7 @@ public:
     int path_history_position() const { return m_path_history_position; }
     static RefPtr<LauncherHandler> get_default_launch_handler(Vector<NonnullRefPtr<LauncherHandler>> const& handlers);
     static Vector<NonnullRefPtr<LauncherHandler>> get_launch_handlers(URL const& url);
-    static Vector<NonnullRefPtr<LauncherHandler>> get_launch_handlers(DeprecatedString const& path);
+    static Vector<NonnullRefPtr<LauncherHandler>> get_launch_handlers(ByteString const& path);
 
     void refresh();
 
@@ -82,7 +82,7 @@ public:
     void set_view_mode(ViewMode);
     ViewMode view_mode() const { return m_view_mode; }
 
-    void set_view_mode_from_string(DeprecatedString const&);
+    void set_view_mode_from_string(ByteString const&);
 
     GUI::AbstractView& current_view()
     {
@@ -120,7 +120,7 @@ public:
 
     bool is_desktop() const { return m_mode == Mode::Desktop; }
 
-    Vector<DeprecatedString> selected_file_paths() const;
+    Vector<ByteString> selected_file_paths() const;
 
     GUI::Action& mkdir_action() { return *m_mkdir_action; }
     GUI::Action& touch_action() { return *m_touch_action; }
@@ -166,8 +166,8 @@ private:
     NonnullRefPtr<GUI::FileSystemModel> m_model;
     NonnullRefPtr<GUI::SortingProxyModel> m_sorting_model;
     size_t m_path_history_position { 0 };
-    Vector<DeprecatedString> m_path_history;
-    void add_path_to_history(DeprecatedString);
+    Vector<ByteString> m_path_history;
+    void add_path_to_history(ByteString);
 
     RefPtr<GUI::Label> m_error_label;
 
diff --git a/Userland/Applications/FileManager/FileOperationProgressWidget.cpp b/Userland/Applications/FileManager/FileOperationProgressWidget.cpp
index 100b8e76ffe..8d4033068a1 100644
--- a/Userland/Applications/FileManager/FileOperationProgressWidget.cpp
+++ b/Userland/Applications/FileManager/FileOperationProgressWidget.cpp
@@ -134,11 +134,11 @@ void FileOperationProgressWidget::did_error(StringView message)
 {
     // FIXME: Communicate more with the user about errors.
     close_pipe();
-    GUI::MessageBox::show(window(), DeprecatedString::formatted("An error occurred: {}", message), "Error"sv, GUI::MessageBox::Type::Error, GUI::MessageBox::InputType::OK);
+    GUI::MessageBox::show(window(), ByteString::formatted("An error occurred: {}", message), "Error"sv, GUI::MessageBox::Type::Error, GUI::MessageBox::InputType::OK);
     window()->close();
 }
 
-DeprecatedString FileOperationProgressWidget::estimate_time(off_t bytes_done, off_t total_byte_count)
+ByteString FileOperationProgressWidget::estimate_time(off_t bytes_done, off_t total_byte_count)
 {
     i64 const elapsed_seconds = m_elapsed_timer.elapsed_time().to_seconds();
 
@@ -149,7 +149,7 @@ DeprecatedString FileOperationProgressWidget::estimate_time(off_t bytes_done, of
     int seconds_remaining = (bytes_left * elapsed_seconds) / bytes_done;
 
     if (seconds_remaining < 30)
-        return DeprecatedString::formatted("{} seconds", 5 + seconds_remaining - seconds_remaining % 5);
+        return ByteString::formatted("{} seconds", 5 + seconds_remaining - seconds_remaining % 5);
     if (seconds_remaining < 60)
         return "About a minute";
     if (seconds_remaining < 90)
@@ -162,14 +162,14 @@ DeprecatedString FileOperationProgressWidget::estimate_time(off_t bytes_done, of
 
     if (minutes_remaining < 60) {
         if (seconds_remaining < 30)
-            return DeprecatedString::formatted("About {} minutes", minutes_remaining);
-        return DeprecatedString::formatted("Over {} minutes", minutes_remaining);
+            return ByteString::formatted("About {} minutes", minutes_remaining);
+        return ByteString::formatted("Over {} minutes", minutes_remaining);
     }
 
     time_t hours_remaining = minutes_remaining / 60;
     minutes_remaining %= 60;
 
-    return DeprecatedString::formatted("{} hours and {} minutes", hours_remaining, minutes_remaining);
+    return ByteString::formatted("{} hours and {} minutes", hours_remaining, minutes_remaining);
 }
 
 void FileOperationProgressWidget::did_progress(off_t bytes_done, off_t total_byte_count, size_t files_done, size_t total_file_count, [[maybe_unused]] off_t current_file_done, [[maybe_unused]] off_t current_file_size, StringView current_filename)
@@ -195,7 +195,7 @@ void FileOperationProgressWidget::did_progress(off_t bytes_done, off_t total_byt
         VERIFY_NOT_REACHED();
     }
 
-    estimated_time_label.set_text(String::from_deprecated_string(estimate_time(bytes_done, total_byte_count)).release_value_but_fixme_should_propagate_errors());
+    estimated_time_label.set_text(String::from_byte_string(estimate_time(bytes_done, total_byte_count)).release_value_but_fixme_should_propagate_errors());
 
     if (total_byte_count) {
         window()->set_progress(100.0f * bytes_done / total_byte_count);
diff --git a/Userland/Applications/FileManager/FileOperationProgressWidget.h b/Userland/Applications/FileManager/FileOperationProgressWidget.h
index 79f07d51db6..3a404531d7c 100644
--- a/Userland/Applications/FileManager/FileOperationProgressWidget.h
+++ b/Userland/Applications/FileManager/FileOperationProgressWidget.h
@@ -29,7 +29,7 @@ private:
 
     void close_pipe();
 
-    DeprecatedString estimate_time(off_t bytes_done, off_t total_byte_count);
+    ByteString estimate_time(off_t bytes_done, off_t total_byte_count);
     Core::ElapsedTimer m_elapsed_timer;
 
     FileOperation m_operation;
diff --git a/Userland/Applications/FileManager/FileUtils.cpp b/Userland/Applications/FileManager/FileUtils.cpp
index 3132d54c8a4..bdce233702c 100644
--- a/Userland/Applications/FileManager/FileUtils.cpp
+++ b/Userland/Applications/FileManager/FileUtils.cpp
@@ -19,13 +19,13 @@ namespace FileManager {
 
 HashTable<NonnullRefPtr<GUI::Window>> file_operation_windows;
 
-void delete_paths(Vector<DeprecatedString> const& paths, bool should_confirm, GUI::Window* parent_window)
+void delete_paths(Vector<ByteString> const& paths, bool should_confirm, GUI::Window* parent_window)
 {
-    DeprecatedString message;
+    ByteString message;
     if (paths.size() == 1) {
-        message = DeprecatedString::formatted("Are you sure you want to delete \"{}\"?", LexicalPath::basename(paths[0]));
+        message = ByteString::formatted("Are you sure you want to delete \"{}\"?", LexicalPath::basename(paths[0]));
     } else {
-        message = DeprecatedString::formatted("Are you sure you want to delete {} files?", paths.size());
+        message = ByteString::formatted("Are you sure you want to delete {} files?", paths.size());
     }
 
     if (should_confirm) {
@@ -42,7 +42,7 @@ void delete_paths(Vector<DeprecatedString> const& paths, bool should_confirm, GU
         _exit(1);
 }
 
-ErrorOr<void> run_file_operation(FileOperation operation, Vector<DeprecatedString> const& sources, DeprecatedString const& destination, GUI::Window* parent_window)
+ErrorOr<void> run_file_operation(FileOperation operation, Vector<ByteString> const& sources, ByteString const& destination, GUI::Window* parent_window)
 {
     auto pipe_fds = TRY(Core::System::pipe2(0));
 
@@ -110,7 +110,7 @@ ErrorOr<void> run_file_operation(FileOperation operation, Vector<DeprecatedStrin
     return {};
 }
 
-ErrorOr<bool> handle_drop(GUI::DropEvent const& event, DeprecatedString const& destination, GUI::Window* window)
+ErrorOr<bool> handle_drop(GUI::DropEvent const& event, ByteString const& destination, GUI::Window* window)
 {
     bool has_accepted_drop = false;
 
@@ -127,12 +127,12 @@ ErrorOr<bool> handle_drop(GUI::DropEvent const& event, DeprecatedString const& d
     if (!FileSystem::is_directory(target))
         return has_accepted_drop;
 
-    Vector<DeprecatedString> paths_to_copy;
+    Vector<ByteString> paths_to_copy;
     for (auto& url_to_copy : urls) {
         auto file_path = url_to_copy.serialize_path();
         if (!url_to_copy.is_valid() || file_path == target)
             continue;
-        auto new_path = DeprecatedString::formatted("{}/{}", target, LexicalPath::basename(file_path));
+        auto new_path = ByteString::formatted("{}/{}", target, LexicalPath::basename(file_path));
         if (file_path == new_path)
             continue;
 
diff --git a/Userland/Applications/FileManager/FileUtils.h b/Userland/Applications/FileManager/FileUtils.h
index b64b4133703..d43a10f207a 100644
--- a/Userland/Applications/FileManager/FileUtils.h
+++ b/Userland/Applications/FileManager/FileUtils.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/Forward.h>
 #include <LibGUI/Forward.h>
 
@@ -19,8 +19,8 @@ enum class FileOperation {
     Delete,
 };
 
-void delete_paths(Vector<DeprecatedString> const&, bool should_confirm, GUI::Window*);
+void delete_paths(Vector<ByteString> const&, bool should_confirm, GUI::Window*);
 
-ErrorOr<void> run_file_operation(FileOperation, Vector<DeprecatedString> const& sources, DeprecatedString const& destination, GUI::Window*);
-ErrorOr<bool> handle_drop(GUI::DropEvent const& event, DeprecatedString const& destination, GUI::Window* window);
+ErrorOr<void> run_file_operation(FileOperation, Vector<ByteString> const& sources, ByteString const& destination, GUI::Window*);
+ErrorOr<bool> handle_drop(GUI::DropEvent const& event, ByteString const& destination, GUI::Window* window);
 }
diff --git a/Userland/Applications/FileManager/PropertiesWindow.cpp b/Userland/Applications/FileManager/PropertiesWindow.cpp
index 6264f6f6945..e4dbd5b9a57 100644
--- a/Userland/Applications/FileManager/PropertiesWindow.cpp
+++ b/Userland/Applications/FileManager/PropertiesWindow.cpp
@@ -47,7 +47,7 @@
 #include <string.h>
 #include <unistd.h>
 
-ErrorOr<NonnullRefPtr<PropertiesWindow>> PropertiesWindow::try_create(DeprecatedString const& path, bool disable_rename, Window* parent)
+ErrorOr<NonnullRefPtr<PropertiesWindow>> PropertiesWindow::try_create(ByteString const& path, bool disable_rename, Window* parent)
 {
     auto window = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) PropertiesWindow(path, parent)));
     window->set_icon(TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/properties.png"sv)));
@@ -55,7 +55,7 @@ ErrorOr<NonnullRefPtr<PropertiesWindow>> PropertiesWindow::try_create(Deprecated
     return window;
 }
 
-PropertiesWindow::PropertiesWindow(DeprecatedString const& path, Window* parent_window)
+PropertiesWindow::PropertiesWindow(ByteString const& path, Window* parent_window)
     : Window(parent_window)
 {
     auto lexical_path = LexicalPath(path);
@@ -134,15 +134,15 @@ ErrorOr<void> PropertiesWindow::create_general_tab(GUI::TabWidget& tab_widget, b
     };
 
     auto* location = general_tab.find_descendant_of_type_named<GUI::LinkLabel>("location");
-    location->set_text(TRY(String::from_deprecated_string(m_path)));
+    location->set_text(TRY(String::from_byte_string(m_path)));
     location->on_click = [this] {
         Desktop::Launcher::open(URL::create_with_file_scheme(m_parent_path, m_name));
     };
 
     auto st = TRY(Core::System::lstat(m_path));
 
-    DeprecatedString owner_name;
-    DeprecatedString group_name;
+    ByteString owner_name;
+    ByteString group_name;
 
     if (auto* pw = getpwuid(st.st_uid)) {
         owner_name = pw->pw_name;
@@ -171,7 +171,7 @@ ErrorOr<void> PropertiesWindow::create_general_tab(GUI::TabWidget& tab_widget, b
             auto* link_location = general_tab.find_descendant_of_type_named<GUI::LinkLabel>("link_location");
             link_location->set_text(link_destination);
             link_location->on_click = [link_destination] {
-                auto link_directory = LexicalPath(link_destination.to_deprecated_string());
+                auto link_directory = LexicalPath(link_destination.to_byte_string());
                 Desktop::Launcher::open(URL::create_with_file_scheme(link_directory.dirname(), link_directory.basename()));
             };
         }
@@ -183,7 +183,7 @@ ErrorOr<void> PropertiesWindow::create_general_tab(GUI::TabWidget& tab_widget, b
     m_size_label = general_tab.find_descendant_of_type_named<GUI::Label>("size");
     m_size_label->set_text(S_ISDIR(st.st_mode)
             ? "Calculating..."_string
-            : TRY(String::from_deprecated_string(human_readable_size_long(st.st_size, UseThousandsSeparator::Yes))));
+            : TRY(String::from_byte_string(human_readable_size_long(st.st_size, UseThousandsSeparator::Yes))));
 
     auto* owner = general_tab.find_descendant_of_type_named<GUI::Label>("owner");
     owner->set_text(String::formatted("{} ({})", owner_name, st.st_uid).release_value_but_fixme_should_propagate_errors());
@@ -192,10 +192,10 @@ ErrorOr<void> PropertiesWindow::create_general_tab(GUI::TabWidget& tab_widget, b
     group->set_text(String::formatted("{} ({})", group_name, st.st_gid).release_value_but_fixme_should_propagate_errors());
 
     auto* created_at = general_tab.find_descendant_of_type_named<GUI::Label>("created_at");
-    created_at->set_text(String::from_deprecated_string(GUI::FileSystemModel::timestamp_string(st.st_ctime)).release_value_but_fixme_should_propagate_errors());
+    created_at->set_text(String::from_byte_string(GUI::FileSystemModel::timestamp_string(st.st_ctime)).release_value_but_fixme_should_propagate_errors());
 
     auto* last_modified = general_tab.find_descendant_of_type_named<GUI::Label>("last_modified");
-    last_modified->set_text(String::from_deprecated_string(GUI::FileSystemModel::timestamp_string(st.st_mtime)).release_value_but_fixme_should_propagate_errors());
+    last_modified->set_text(String::from_byte_string(GUI::FileSystemModel::timestamp_string(st.st_mtime)).release_value_but_fixme_should_propagate_errors());
 
     auto* owner_read = general_tab.find_descendant_of_type_named<GUI::CheckBox>("owner_read");
     auto* owner_write = general_tab.find_descendant_of_type_named<GUI::CheckBox>("owner_write");
@@ -263,7 +263,7 @@ ErrorOr<void> PropertiesWindow::create_archive_tab(GUI::TabWidget& tab_widget, N
     tab.find_descendant_of_type_named<GUI::Label>("archive_file_count")->set_text(TRY(String::number(statistics.file_count())));
     tab.find_descendant_of_type_named<GUI::Label>("archive_format")->set_text("ZIP"_string);
     tab.find_descendant_of_type_named<GUI::Label>("archive_directory_count")->set_text(TRY(String::number(statistics.directory_count())));
-    tab.find_descendant_of_type_named<GUI::Label>("archive_uncompressed_size")->set_text(TRY(String::from_deprecated_string(AK::human_readable_size(statistics.total_uncompressed_bytes()))));
+    tab.find_descendant_of_type_named<GUI::Label>("archive_uncompressed_size")->set_text(TRY(String::from_byte_string(AK::human_readable_size(statistics.total_uncompressed_bytes()))));
 
     return {};
 }
@@ -280,9 +280,9 @@ ErrorOr<void> PropertiesWindow::create_audio_tab(GUI::TabWidget& tab_widget, Non
     auto& tab = tab_widget.add_tab<GUI::Widget>("Audio"_string);
     TRY(tab.load_from_gml(properties_window_audio_tab_gml));
 
-    tab.find_descendant_of_type_named<GUI::Label>("audio_type")->set_text(TRY(String::from_deprecated_string(loader->format_name())));
+    tab.find_descendant_of_type_named<GUI::Label>("audio_type")->set_text(TRY(String::from_byte_string(loader->format_name())));
     auto duration_seconds = loader->total_samples() / loader->sample_rate();
-    tab.find_descendant_of_type_named<GUI::Label>("audio_duration")->set_text(TRY(String::from_deprecated_string(human_readable_digital_time(duration_seconds))));
+    tab.find_descendant_of_type_named<GUI::Label>("audio_duration")->set_text(TRY(String::from_byte_string(human_readable_digital_time(duration_seconds))));
     tab.find_descendant_of_type_named<GUI::Label>("audio_sample_rate")->set_text(TRY(String::formatted("{} Hz", loader->sample_rate())));
     tab.find_descendant_of_type_named<GUI::Label>("audio_format")->set_text(TRY(String::formatted("{}-bit", loader->bits_per_sample())));
 
@@ -487,12 +487,12 @@ ErrorOr<void> PropertiesWindow::create_pdf_tab(GUI::TabWidget& tab_widget, Nonnu
     if (maybe_info_dict.is_error()) {
         warnln("Failed to read InfoDict from '{}': {}", m_path, maybe_info_dict.error().message());
     } else if (maybe_info_dict.value().has_value()) {
-        auto get_info_string = [](PDF::PDFErrorOr<Optional<DeprecatedString>> input) -> ErrorOr<String> {
+        auto get_info_string = [](PDF::PDFErrorOr<Optional<ByteString>> input) -> ErrorOr<String> {
             if (input.is_error())
                 return String {};
             if (!input.value().has_value())
                 return String {};
-            return String::from_deprecated_string(input.value().value());
+            return String::from_byte_string(input.value().value());
         };
 
         auto info_dict = maybe_info_dict.release_value().release_value();
@@ -512,7 +512,7 @@ ErrorOr<void> PropertiesWindow::create_pdf_tab(GUI::TabWidget& tab_widget, Nonnu
 void PropertiesWindow::update()
 {
     m_icon->set_bitmap(GUI::FileIconProvider::icon_for_path(make_full_path(m_name), m_mode).bitmap_for_size(32));
-    set_title(DeprecatedString::formatted("{} - Properties", m_name));
+    set_title(ByteString::formatted("{} - Properties", m_name));
 }
 
 void PropertiesWindow::permission_changed(mode_t mask, bool set)
@@ -527,24 +527,24 @@ void PropertiesWindow::permission_changed(mode_t mask, bool set)
     m_apply_button->set_enabled(m_name_dirty || m_permissions_dirty);
 }
 
-DeprecatedString PropertiesWindow::make_full_path(DeprecatedString const& name)
+ByteString PropertiesWindow::make_full_path(ByteString const& name)
 {
-    return DeprecatedString::formatted("{}/{}", m_parent_path, name);
+    return ByteString::formatted("{}/{}", m_parent_path, name);
 }
 
 bool PropertiesWindow::apply_changes()
 {
     if (m_name_dirty) {
-        DeprecatedString new_name = m_name_box->text();
-        DeprecatedString new_file = make_full_path(new_name).characters();
+        ByteString new_name = m_name_box->text();
+        ByteString new_file = make_full_path(new_name).characters();
 
         if (FileSystem::exists(new_file)) {
-            GUI::MessageBox::show(this, DeprecatedString::formatted("A file \"{}\" already exists!", new_name), "Error"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(this, ByteString::formatted("A file \"{}\" already exists!", new_name), "Error"sv, GUI::MessageBox::Type::Error);
             return false;
         }
 
         if (rename(make_full_path(m_name).characters(), new_file.characters())) {
-            GUI::MessageBox::show(this, DeprecatedString::formatted("Could not rename file: {}!", strerror(errno)), "Error"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(this, ByteString::formatted("Could not rename file: {}!", strerror(errno)), "Error"sv, GUI::MessageBox::Type::Error);
             return false;
         }
 
@@ -555,7 +555,7 @@ bool PropertiesWindow::apply_changes()
 
     if (m_permissions_dirty) {
         if (chmod(make_full_path(m_name).characters(), m_mode)) {
-            GUI::MessageBox::show(this, DeprecatedString::formatted("Could not update permissions: {}!", strerror(errno)), "Error"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(this, ByteString::formatted("Could not update permissions: {}!", strerror(errno)), "Error"sv, GUI::MessageBox::Type::Error);
             return false;
         }
 
@@ -606,7 +606,7 @@ void PropertiesWindow::close()
         m_directory_statistics_calculator->stop();
 }
 
-PropertiesWindow::DirectoryStatisticsCalculator::DirectoryStatisticsCalculator(DeprecatedString path)
+PropertiesWindow::DirectoryStatisticsCalculator::DirectoryStatisticsCalculator(ByteString path)
 {
     m_work_queue.enqueue(path);
 }
diff --git a/Userland/Applications/FileManager/PropertiesWindow.h b/Userland/Applications/FileManager/PropertiesWindow.h
index cbf54466dbf..877ff582ac2 100644
--- a/Userland/Applications/FileManager/PropertiesWindow.h
+++ b/Userland/Applications/FileManager/PropertiesWindow.h
@@ -20,13 +20,13 @@ class PropertiesWindow final : public GUI::Window {
     C_OBJECT(PropertiesWindow);
 
 public:
-    static ErrorOr<NonnullRefPtr<PropertiesWindow>> try_create(DeprecatedString const& path, bool disable_rename, Window* parent = nullptr);
+    static ErrorOr<NonnullRefPtr<PropertiesWindow>> try_create(ByteString const& path, bool disable_rename, Window* parent = nullptr);
     virtual ~PropertiesWindow() override = default;
 
     virtual void close() final;
 
 private:
-    PropertiesWindow(DeprecatedString const& path, Window* parent = nullptr);
+    PropertiesWindow(ByteString const& path, Window* parent = nullptr);
     ErrorOr<void> create_widgets(bool disable_rename);
     ErrorOr<void> create_general_tab(GUI::TabWidget&, bool disable_rename);
     ErrorOr<void> create_file_type_specific_tabs(GUI::TabWidget&);
@@ -44,7 +44,7 @@ private:
 
     class DirectoryStatisticsCalculator final : public RefCounted<DirectoryStatisticsCalculator> {
     public:
-        DirectoryStatisticsCalculator(DeprecatedString path);
+        DirectoryStatisticsCalculator(ByteString path);
         void start();
         void stop();
         Function<void(off_t total_size_in_bytes, size_t file_count, size_t directory_count)> on_update;
@@ -54,7 +54,7 @@ private:
         size_t m_file_count { 0 };
         size_t m_directory_count { 0 };
         RefPtr<Threading::BackgroundAction<int>> m_background_action;
-        Queue<DeprecatedString> m_work_queue;
+        Queue<ByteString> m_work_queue;
     };
 
     static StringView const get_description(mode_t const mode)
@@ -84,7 +84,7 @@ private:
     void permission_changed(mode_t mask, bool set);
     bool apply_changes();
     void update();
-    DeprecatedString make_full_path(DeprecatedString const& name);
+    ByteString make_full_path(ByteString const& name);
 
     RefPtr<GUI::Button> m_apply_button;
     RefPtr<GUI::TextBox> m_name_box;
@@ -92,9 +92,9 @@ private:
     RefPtr<GUI::Label> m_size_label;
     RefPtr<DirectoryStatisticsCalculator> m_directory_statistics_calculator;
     RefPtr<GUI::Action> m_on_escape;
-    DeprecatedString m_name;
-    DeprecatedString m_parent_path;
-    DeprecatedString m_path;
+    ByteString m_name;
+    ByteString m_parent_path;
+    ByteString m_path;
     mode_t m_mode { 0 };
     mode_t m_old_mode { 0 };
     bool m_permissions_dirty { false };
diff --git a/Userland/Applications/FileManager/main.cpp b/Userland/Applications/FileManager/main.cpp
index c4757ab1c3e..29c7bfd8ca1 100644
--- a/Userland/Applications/FileManager/main.cpp
+++ b/Userland/Applications/FileManager/main.cpp
@@ -59,15 +59,15 @@
 using namespace FileManager;
 
 static ErrorOr<int> run_in_desktop_mode();
-static ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, DeprecatedString const& entry_focused_on_init);
-static void do_copy(Vector<DeprecatedString> const& selected_file_paths, FileOperation file_operation);
-static void do_paste(DeprecatedString const& target_directory, GUI::Window* window);
-static void do_create_link(Vector<DeprecatedString> const& selected_file_paths, GUI::Window* window);
-static void do_create_archive(Vector<DeprecatedString> const& selected_file_paths, GUI::Window* window);
-static void do_set_wallpaper(DeprecatedString const& file_path, GUI::Window* window);
-static void do_unzip_archive(Vector<DeprecatedString> const& selected_file_paths, GUI::Window* window);
-static void show_properties(DeprecatedString const& container_dir_path, DeprecatedString const& path, Vector<DeprecatedString> const& selected, GUI::Window* window);
-static bool add_launch_handler_actions_to_menu(RefPtr<GUI::Menu>& menu, DirectoryView const& directory_view, DeprecatedString const& full_path, RefPtr<GUI::Action>& default_action, Vector<NonnullRefPtr<LauncherHandler>>& current_file_launch_handlers);
+static ErrorOr<int> run_in_windowed_mode(ByteString const& initial_location, ByteString const& entry_focused_on_init);
+static void do_copy(Vector<ByteString> const& selected_file_paths, FileOperation file_operation);
+static void do_paste(ByteString const& target_directory, GUI::Window* window);
+static void do_create_link(Vector<ByteString> const& selected_file_paths, GUI::Window* window);
+static void do_create_archive(Vector<ByteString> const& selected_file_paths, GUI::Window* window);
+static void do_set_wallpaper(ByteString const& file_path, GUI::Window* window);
+static void do_unzip_archive(Vector<ByteString> const& selected_file_paths, GUI::Window* window);
+static void show_properties(ByteString const& container_dir_path, ByteString const& path, Vector<ByteString> const& selected, GUI::Window* window);
+static bool add_launch_handler_actions_to_menu(RefPtr<GUI::Menu>& menu, DirectoryView const& directory_view, ByteString const& full_path, RefPtr<GUI::Action>& default_action, Vector<NonnullRefPtr<LauncherHandler>>& current_file_launch_handlers);
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
@@ -82,7 +82,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     bool is_desktop_mode { false };
     bool is_selection_mode { false };
     bool ignore_path_resolution { false };
-    DeprecatedString initial_location;
+    ByteString initial_location;
     args_parser.add_option(is_desktop_mode, "Run in desktop mode", "desktop", 'd');
     args_parser.add_option(is_selection_mode, "Show entry in parent folder", "select", 's');
     args_parser.add_option(ignore_path_resolution, "Use raw path, do not resolve real path", "raw", 'r');
@@ -109,7 +109,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     LexicalPath path(initial_location);
     if (!initial_location.is_empty()) {
         if (auto error_or_path = FileSystem::real_path(initial_location); !ignore_path_resolution && !error_or_path.is_error())
-            initial_location = error_or_path.release_value().to_deprecated_string();
+            initial_location = error_or_path.release_value().to_byte_string();
 
         if (!FileSystem::is_directory(initial_location)) {
             // We want to extract zips to a temporary directory when FileManager is launched with a .zip file as its first argument
@@ -134,7 +134,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                     return -1;
                 }
 
-                return run_in_windowed_mode(temp_directory_path.to_deprecated_string(), path.basename());
+                return run_in_windowed_mode(temp_directory_path.to_byte_string(), path.basename());
             }
 
             is_selection_mode = true;
@@ -142,7 +142,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
 
     if (auto error_or_cwd = FileSystem::current_working_directory(); initial_location.is_empty() && !error_or_cwd.is_error())
-        initial_location = error_or_cwd.release_value().to_deprecated_string();
+        initial_location = error_or_cwd.release_value().to_byte_string();
 
     if (initial_location.is_empty())
         initial_location = Core::StandardPaths::home_directory();
@@ -150,7 +150,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     if (initial_location.is_empty())
         initial_location = "/";
 
-    DeprecatedString focused_entry;
+    ByteString focused_entry;
     if (is_selection_mode) {
         initial_location = path.dirname();
         focused_entry = path.basename();
@@ -159,7 +159,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     return run_in_windowed_mode(initial_location, focused_entry);
 }
 
-void do_copy(Vector<DeprecatedString> const& selected_file_paths, FileOperation file_operation)
+void do_copy(Vector<ByteString> const& selected_file_paths, FileOperation file_operation)
 {
     VERIFY(!selected_file_paths.is_empty());
 
@@ -171,17 +171,17 @@ void do_copy(Vector<DeprecatedString> const& selected_file_paths, FileOperation
         auto url = URL::create_with_file_scheme(path);
         copy_text.appendff("{}\n", url);
     }
-    GUI::Clipboard::the().set_data(copy_text.to_deprecated_string().bytes(), "text/uri-list");
+    GUI::Clipboard::the().set_data(copy_text.to_byte_string().bytes(), "text/uri-list");
 }
 
-void do_paste(DeprecatedString const& target_directory, GUI::Window* window)
+void do_paste(ByteString const& target_directory, GUI::Window* window)
 {
     auto data_and_type = GUI::Clipboard::the().fetch_data_and_type();
     if (data_and_type.mime_type != "text/uri-list") {
         dbgln("Cannot paste clipboard type {}", data_and_type.mime_type);
         return;
     }
-    auto copied_lines = DeprecatedString::copy(data_and_type.data).split('\n');
+    auto copied_lines = ByteString::copy(data_and_type.data).split('\n');
     if (copied_lines.is_empty()) {
         dbgln("No files to paste");
         return;
@@ -193,7 +193,7 @@ void do_paste(DeprecatedString const& target_directory, GUI::Window* window)
         copied_lines.remove(0);
     }
 
-    Vector<DeprecatedString> source_paths;
+    Vector<ByteString> source_paths;
     for (auto& uri_as_string : copied_lines) {
         if (uri_as_string.is_empty())
             continue;
@@ -211,17 +211,17 @@ void do_paste(DeprecatedString const& target_directory, GUI::Window* window)
     }
 }
 
-void do_create_link(Vector<DeprecatedString> const& selected_file_paths, GUI::Window* window)
+void do_create_link(Vector<ByteString> const& selected_file_paths, GUI::Window* window)
 {
     auto path = selected_file_paths.first();
-    auto destination = DeprecatedString::formatted("{}/{}", Core::StandardPaths::desktop_directory(), LexicalPath::basename(path));
+    auto destination = ByteString::formatted("{}/{}", Core::StandardPaths::desktop_directory(), LexicalPath::basename(path));
     if (auto result = FileSystem::link_file(destination, path); result.is_error()) {
-        GUI::MessageBox::show(window, DeprecatedString::formatted("Could not create desktop shortcut:\n{}", result.error()), "File Manager"sv,
+        GUI::MessageBox::show(window, ByteString::formatted("Could not create desktop shortcut:\n{}", result.error()), "File Manager"sv,
             GUI::MessageBox::Type::Error);
     }
 }
 
-void do_create_archive(Vector<DeprecatedString> const& selected_file_paths, GUI::Window* window)
+void do_create_archive(Vector<ByteString> const& selected_file_paths, GUI::Window* window)
 {
     String archive_name;
     if (GUI::InputBox::show(window, archive_name, "Enter name:"sv, "Create Archive"sv) != GUI::InputBox::ExecResult::OK)
@@ -240,7 +240,7 @@ void do_create_archive(Vector<DeprecatedString> const& selected_file_paths, GUI:
         if (!AK::StringUtils::ends_with(archive_name, ".zip"sv, CaseSensitivity::CaseSensitive))
             path_builder.append(".zip"sv);
     }
-    auto output_path = path_builder.to_deprecated_string();
+    auto output_path = path_builder.to_byte_string();
 
     pid_t zip_pid = fork();
     if (zip_pid < 0) {
@@ -249,7 +249,7 @@ void do_create_archive(Vector<DeprecatedString> const& selected_file_paths, GUI:
     }
 
     if (!zip_pid) {
-        Vector<DeprecatedString> relative_paths;
+        Vector<ByteString> relative_paths;
         Vector<char const*> arg_list;
         arg_list.append("/bin/zip");
         arg_list.append("-r");
@@ -273,10 +273,10 @@ void do_create_archive(Vector<DeprecatedString> const& selected_file_paths, GUI:
     }
 }
 
-void do_set_wallpaper(DeprecatedString const& file_path, GUI::Window* window)
+void do_set_wallpaper(ByteString const& file_path, GUI::Window* window)
 {
     auto show_error = [&] {
-        GUI::MessageBox::show(window, DeprecatedString::formatted("Failed to set {} as wallpaper.", file_path), "Failed to set wallpaper"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(window, ByteString::formatted("Failed to set {} as wallpaper.", file_path), "Failed to set wallpaper"sv, GUI::MessageBox::Type::Error);
     };
 
     auto bitmap_or_error = Gfx::Bitmap::load_from_file(file_path);
@@ -289,10 +289,10 @@ void do_set_wallpaper(DeprecatedString const& file_path, GUI::Window* window)
         show_error();
 }
 
-void do_unzip_archive(Vector<DeprecatedString> const& selected_file_paths, GUI::Window* window)
+void do_unzip_archive(Vector<ByteString> const& selected_file_paths, GUI::Window* window)
 {
-    DeprecatedString archive_file_path = selected_file_paths.first();
-    DeprecatedString output_directory_path = archive_file_path.substring(0, archive_file_path.length() - 4);
+    ByteString archive_file_path = selected_file_paths.first();
+    ByteString output_directory_path = archive_file_path.substring(0, archive_file_path.length() - 4);
 
     pid_t unzip_pid = fork();
     if (unzip_pid < 0) {
@@ -315,7 +315,7 @@ void do_unzip_archive(Vector<DeprecatedString> const& selected_file_paths, GUI::
     }
 }
 
-void show_properties(DeprecatedString const& container_dir_path, DeprecatedString const& path, Vector<DeprecatedString> const& selected, GUI::Window* window)
+void show_properties(ByteString const& container_dir_path, ByteString const& path, Vector<ByteString> const& selected, GUI::Window* window)
 {
     ErrorOr<RefPtr<PropertiesWindow>> properties_or_error = nullptr;
     if (selected.is_empty()) {
@@ -337,7 +337,7 @@ void show_properties(DeprecatedString const& container_dir_path, DeprecatedStrin
     properties->show();
 }
 
-bool add_launch_handler_actions_to_menu(RefPtr<GUI::Menu>& menu, DirectoryView const& directory_view, DeprecatedString const& full_path, RefPtr<GUI::Action>& default_action, Vector<NonnullRefPtr<LauncherHandler>>& current_file_launch_handlers)
+bool add_launch_handler_actions_to_menu(RefPtr<GUI::Menu>& menu, DirectoryView const& directory_view, ByteString const& full_path, RefPtr<GUI::Action>& default_action, Vector<NonnullRefPtr<LauncherHandler>>& current_file_launch_handlers)
 {
     current_file_launch_handlers = directory_view.get_launch_handlers(full_path);
 
@@ -348,9 +348,9 @@ bool add_launch_handler_actions_to_menu(RefPtr<GUI::Menu>& menu, DirectoryView c
             directory_view.launch(URL::create_with_file_scheme(full_path), launcher_handler);
         });
         if (default_file_handler->details().launcher_type == Desktop::Launcher::LauncherType::Application)
-            file_open_action->set_text(DeprecatedString::formatted("Run {}", file_open_action->text()));
+            file_open_action->set_text(ByteString::formatted("Run {}", file_open_action->text()));
         else
-            file_open_action->set_text(DeprecatedString::formatted("Open in {}", file_open_action->text()));
+            file_open_action->set_text(ByteString::formatted("Open in {}", file_open_action->text()));
 
         default_action = file_open_action;
 
@@ -458,8 +458,8 @@ ErrorOr<int> run_in_desktop_mode()
 
     auto properties_action = GUI::CommonActions::make_properties_action(
         [&](auto&) {
-            DeprecatedString path = directory_view->path();
-            Vector<DeprecatedString> selected = directory_view->selected_file_paths();
+            ByteString path = directory_view->path();
+            Vector<ByteString> selected = directory_view->selected_file_paths();
 
             show_properties(path, path, selected, directory_view->window());
         },
@@ -472,7 +472,7 @@ ErrorOr<int> run_in_desktop_mode()
         window);
     paste_action->set_enabled(GUI::Clipboard::the().fetch_mime_type() == "text/uri-list" && access(directory_view->path().characters(), W_OK) == 0);
 
-    GUI::Clipboard::the().on_change = [&](DeprecatedString const& data_type) {
+    GUI::Clipboard::the().on_change = [&](ByteString const& data_type) {
         paste_action->set_enabled(data_type == "text/uri-list" && access(directory_view->path().characters(), W_OK) == 0);
     };
 
@@ -604,7 +604,7 @@ ErrorOr<int> run_in_desktop_mode()
     return GUI::Application::the()->exec();
 }
 
-ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, DeprecatedString const& entry_focused_on_init)
+ErrorOr<int> run_in_windowed_mode(ByteString const& initial_location, ByteString const& entry_focused_on_init)
 {
     auto window = GUI::Window::construct();
     window->set_title("File Manager");
@@ -762,7 +762,7 @@ ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, Depr
     view_type_action_group->add_action(directory_view->view_as_columns_action());
 
     auto tree_view_selected_file_paths = [&] {
-        Vector<DeprecatedString> paths;
+        Vector<ByteString> paths;
         auto& view = tree_view;
         view.selection().for_each_index([&](GUI::ModelIndex const& index) {
             paths.append(directories_model->full_path(index));
@@ -802,7 +802,7 @@ ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, Depr
 
     auto copy_path_action = GUI::Action::create(
         "Copy Path", [&](GUI::Action const&) {
-            Vector<DeprecatedString> selected_paths;
+            Vector<ByteString> selected_paths;
             if (directory_view->active_widget()->is_focused()) {
                 selected_paths = directory_view->selected_file_paths();
             } else if (tree_view.is_focused()) {
@@ -822,7 +822,7 @@ ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, Depr
             {},
             TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/app-file-manager.png"sv)),
             [&](GUI::Action const& action) {
-                Vector<DeprecatedString> paths;
+                Vector<ByteString> paths;
                 if (action.activator() == tree_view_directory_context_menu)
                     paths = tree_view_selected_file_paths();
                 else
@@ -841,7 +841,7 @@ ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, Depr
             {},
             TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/app-terminal.png"sv)),
             [&](GUI::Action const& action) {
-                Vector<DeprecatedString> paths;
+                Vector<ByteString> paths;
                 if (action.activator() == tree_view_directory_context_menu)
                     paths = tree_view_selected_file_paths();
                 else
@@ -911,9 +911,9 @@ ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, Depr
 
     auto properties_action = GUI::CommonActions::make_properties_action(
         [&](auto& action) {
-            DeprecatedString container_dir_path;
-            DeprecatedString path;
-            Vector<DeprecatedString> selected;
+            ByteString container_dir_path;
+            ByteString path;
+            Vector<ByteString> selected;
             if (action.activator() == directory_context_menu || directory_view->active_widget()->is_focused()) {
                 path = directory_view->path();
                 container_dir_path = path;
@@ -930,7 +930,7 @@ ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, Depr
 
     auto paste_action = GUI::CommonActions::make_paste_action(
         [&](GUI::Action const& action) {
-            DeprecatedString target_directory;
+            ByteString target_directory;
             if (action.activator() == directory_context_menu)
                 target_directory = directory_view->selected_file_paths()[0];
             else
@@ -942,7 +942,7 @@ ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, Depr
 
     auto folder_specific_paste_action = GUI::CommonActions::make_paste_action(
         [&](GUI::Action const& action) {
-            DeprecatedString target_directory;
+            ByteString target_directory;
             if (action.activator() == directory_context_menu)
                 target_directory = directory_view->selected_file_paths()[0];
             else
@@ -970,7 +970,7 @@ ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, Depr
         },
         window);
 
-    GUI::Clipboard::the().on_change = [&](DeprecatedString const& data_type) {
+    GUI::Clipboard::the().on_change = [&](ByteString const& data_type) {
         auto current_location = directory_view->path();
         paste_action->set_enabled(data_type == "text/uri-list" && access(current_location.characters(), W_OK) == 0);
     };
@@ -1108,12 +1108,12 @@ ErrorOr<int> run_in_windowed_mode(DeprecatedString const& initial_location, Depr
         }
     };
 
-    directory_view->on_path_change = [&](DeprecatedString const& new_path, bool can_read_in_path, bool can_write_in_path) {
+    directory_view->on_path_change = [&](ByteString const& new_path, bool can_read_in_path, bool can_write_in_path) {
         auto icon = GUI::FileIconProvider::icon_for_path(new_path);
         auto* bitmap = icon.bitmap_for_size(16);
         window->set_icon(bitmap);
 
-        window->set_title(DeprecatedString::formatted("{} - File Manager", new_path));
+        window->set_title(ByteString::formatted("{} - File Manager", new_path));
 
         breadcrumbbar.set_current_path(new_path);
 
diff --git a/Userland/Applications/FontEditor/MainWidget.cpp b/Userland/Applications/FontEditor/MainWidget.cpp
index 4f7cf3cf5e5..231552bca39 100644
--- a/Userland/Applications/FontEditor/MainWidget.cpp
+++ b/Userland/Applications/FontEditor/MainWidget.cpp
@@ -90,8 +90,8 @@ ErrorOr<RefPtr<GUI::Window>> MainWidget::create_preview_window()
 
     m_preview_textbox = find_descendant_of_type_named<GUI::TextBox>("preview_textbox");
     m_preview_textbox->on_change = [this] {
-        auto maybe_preview = [](DeprecatedString const& deprecated_text) -> ErrorOr<String> {
-            auto text = TRY(String::from_deprecated_string(deprecated_text));
+        auto maybe_preview = [](ByteString const& deprecated_text) -> ErrorOr<String> {
+            auto text = TRY(String::from_byte_string(deprecated_text));
             return TRY(String::formatted("{}\n{}", text, TRY(text.to_uppercase())));
         }(m_preview_textbox->text());
         if (maybe_preview.is_error())
@@ -150,7 +150,7 @@ ErrorOr<void> MainWidget::create_actions()
     m_save_action = GUI::CommonActions::make_save_action([this](auto&) {
         if (m_path.is_empty())
             return m_save_as_action->activate();
-        auto response = FileSystemAccessClient::Client::the().request_file(window(), m_path.to_deprecated_string(), Core::File::OpenMode::Truncate | Core::File::OpenMode::Write);
+        auto response = FileSystemAccessClient::Client::the().request_file(window(), m_path.to_byte_string(), Core::File::OpenMode::Truncate | Core::File::OpenMode::Write);
         if (response.is_error())
             return;
         auto file = response.release_value();
@@ -185,7 +185,7 @@ ErrorOr<void> MainWidget::create_actions()
     });
     m_paste_action->set_enabled(GUI::Clipboard::the().fetch_mime_type() == "glyph/x-fonteditor");
 
-    GUI::Clipboard::the().on_change = [this](DeprecatedString const& data_type) {
+    GUI::Clipboard::the().on_change = [this](ByteString const& data_type) {
         m_paste_action->set_enabled(data_type == "glyph/x-fonteditor");
     };
 
@@ -369,7 +369,7 @@ ErrorOr<void> MainWidget::create_actions()
                 continue;
             builder.append_code_point(code_point);
         }
-        GUI::Clipboard::the().set_plain_text(builder.to_deprecated_string());
+        GUI::Clipboard::the().set_plain_text(builder.to_byte_string());
     });
     m_copy_text_action->set_status_tip("Copy to clipboard as text"_string);
 
@@ -478,9 +478,9 @@ void MainWidget::update_action_text()
     };
 
     if (auto maybe_text = text_or_error("&Undo"sv, m_undo_stack->undo_action_text()); !maybe_text.is_error())
-        m_undo_action->set_text(maybe_text.release_value().to_deprecated_string());
+        m_undo_action->set_text(maybe_text.release_value().to_byte_string());
     if (auto maybe_text = text_or_error("&Redo"sv, m_undo_stack->redo_action_text()); !maybe_text.is_error())
-        m_redo_action->set_text(maybe_text.release_value().to_deprecated_string());
+        m_redo_action->set_text(maybe_text.release_value().to_byte_string());
 }
 
 ErrorOr<void> MainWidget::create_widgets()
@@ -533,13 +533,13 @@ ErrorOr<void> MainWidget::create_widgets()
 
     m_name_textbox = find_descendant_of_type_named<GUI::TextBox>("name_textbox");
     m_name_textbox->on_change = [this] {
-        m_font->set_name(MUST(String::from_deprecated_string(m_name_textbox->text())));
+        m_font->set_name(MUST(String::from_byte_string(m_name_textbox->text())));
         did_modify_font();
     };
 
     m_family_textbox = find_descendant_of_type_named<GUI::TextBox>("family_textbox");
     m_family_textbox->on_change = [this] {
-        m_font->set_family(MUST(String::from_deprecated_string(m_family_textbox->text())));
+        m_font->set_family(MUST(String::from_byte_string(m_family_textbox->text())));
         did_modify_font();
     };
 
@@ -918,7 +918,7 @@ void MainWidget::update_title()
     else
         title.append(m_path);
     title.append("[*] - Font Editor"sv);
-    window()->set_title(title.to_deprecated_string());
+    window()->set_title(title.to_byte_string());
 }
 
 void MainWidget::did_modify_font()
@@ -1034,11 +1034,11 @@ ErrorOr<void> MainWidget::copy_selected_glyphs()
     TRY(buffer.try_append(rows));
     TRY(buffer.try_append(widths));
 
-    HashMap<DeprecatedString, DeprecatedString> metadata;
-    metadata.set("start", DeprecatedString::number(selection.start()));
-    metadata.set("count", DeprecatedString::number(selection.size()));
-    metadata.set("width", DeprecatedString::number(m_font->max_glyph_width()));
-    metadata.set("height", DeprecatedString::number(m_font->glyph_height()));
+    HashMap<ByteString, ByteString> metadata;
+    metadata.set("start", ByteString::number(selection.start()));
+    metadata.set("count", ByteString::number(selection.size()));
+    metadata.set("width", ByteString::number(m_font->max_glyph_width()));
+    metadata.set("height", ByteString::number(m_font->glyph_height()));
     GUI::Clipboard::the().set_data(buffer.bytes(), "glyph/x-fonteditor", metadata);
 
     return {};
diff --git a/Userland/Applications/FontEditor/NewFontDialog.cpp b/Userland/Applications/FontEditor/NewFontDialog.cpp
index 2527f96c417..0f5696453e9 100644
--- a/Userland/Applications/FontEditor/NewFontDialog.cpp
+++ b/Userland/Applications/FontEditor/NewFontDialog.cpp
@@ -218,8 +218,8 @@ NewFontDialog::NewFontDialog(GUI::Window* parent_window)
 
 void NewFontDialog::save_metadata()
 {
-    m_new_font_metadata.name = MUST(String::from_deprecated_string(m_name_textbox->text()));
-    m_new_font_metadata.family = MUST(String::from_deprecated_string(m_family_textbox->text()));
+    m_new_font_metadata.name = MUST(String::from_byte_string(m_name_textbox->text()));
+    m_new_font_metadata.family = MUST(String::from_byte_string(m_family_textbox->text()));
     m_new_font_metadata.weight = Gfx::name_to_weight(m_weight_combobox->text());
     m_new_font_metadata.slope = Gfx::name_to_slope(m_slope_combobox->text());
     m_new_font_metadata.presentation_size = m_presentation_spinbox->value();
diff --git a/Userland/Applications/FontEditor/UndoSelection.h b/Userland/Applications/FontEditor/UndoSelection.h
index 67a15d1cad8..e6b2d585e0d 100644
--- a/Userland/Applications/FontEditor/UndoSelection.h
+++ b/Userland/Applications/FontEditor/UndoSelection.h
@@ -97,7 +97,7 @@ public:
         else
             warnln("Restoring state failed");
     }
-    virtual DeprecatedString action_text() const override { return m_action_text.to_deprecated_string(); }
+    virtual ByteString action_text() const override { return m_action_text.to_byte_string(); }
 
 private:
     NonnullRefPtr<UndoSelection> m_undo_state;
diff --git a/Userland/Applications/FontEditor/main.cpp b/Userland/Applications/FontEditor/main.cpp
index abb5f19489c..6d85f83415a 100644
--- a/Userland/Applications/FontEditor/main.cpp
+++ b/Userland/Applications/FontEditor/main.cpp
@@ -59,7 +59,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     window->show();
 
-    auto default_path = TRY(String::from_deprecated_string(Config::read_string("FontEditor"sv, "Defaults"sv, "Font"sv, {})));
+    auto default_path = TRY(String::from_byte_string(Config::read_string("FontEditor"sv, "Defaults"sv, "Font"sv, {})));
     auto path_to_load = path.is_empty() ? default_path : path;
     if (!path_to_load.is_empty()) {
         auto response = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, path_to_load);
diff --git a/Userland/Applications/GamesSettings/CardSettingsWidget.cpp b/Userland/Applications/GamesSettings/CardSettingsWidget.cpp
index abdf3befd58..fda40fcc069 100644
--- a/Userland/Applications/GamesSettings/CardSettingsWidget.cpp
+++ b/Userland/Applications/GamesSettings/CardSettingsWidget.cpp
@@ -88,7 +88,7 @@ ErrorOr<void> CardSettingsWidget::initialize()
         TRY(m_card_front_sets.try_append(entry.name));
         return IterationDecision::Continue;
     }));
-    auto piece_set_model = GUI::ItemListModel<DeprecatedString>::create(m_card_front_sets);
+    auto piece_set_model = GUI::ItemListModel<ByteString>::create(m_card_front_sets);
     m_card_front_images_combo_box->set_model(piece_set_model);
     auto card_front_set = Config::read_string("Games"sv, "Cards"sv, "CardFrontImages"sv, default_card_front_image_set);
     if (card_front_set.is_empty())
@@ -103,7 +103,7 @@ ErrorOr<void> CardSettingsWidget::initialize()
     m_card_back_image_view = find_descendant_of_type_named<GUI::IconView>("cards_back_image");
     m_card_back_image_view->set_model(GUI::FileSystemModel::create("/res/graphics/cards/backs"));
     m_card_back_image_view->set_model_column(GUI::FileSystemModel::Column::Name);
-    if (!set_card_back_image_path(TRY(String::from_deprecated_string(Config::read_string("Games"sv, "Cards"sv, "CardBackImage"sv)))))
+    if (!set_card_back_image_path(TRY(String::from_byte_string(Config::read_string("Games"sv, "Cards"sv, "CardBackImage"sv)))))
         set_card_back_image_path(default_card_back_image_path);
     m_card_back_image_view->on_selection_change = [&]() {
         auto& card_back_selection = m_card_back_image_view->selection();
@@ -140,7 +140,7 @@ void CardSettingsWidget::reset_default_values()
 
 bool CardSettingsWidget::set_card_back_image_path(StringView path)
 {
-    auto index = static_cast<GUI::FileSystemModel*>(m_card_back_image_view->model())->index(path.to_deprecated_string(), m_card_back_image_view->model_column());
+    auto index = static_cast<GUI::FileSystemModel*>(m_card_back_image_view->model())->index(path.to_byte_string(), m_card_back_image_view->model_column());
     if (index.is_valid()) {
         m_card_back_image_view->set_cursor(index, GUI::AbstractView::SelectionUpdate::Set);
         Cards::CardPainter::the().set_back_image_path(path);
@@ -156,7 +156,7 @@ String CardSettingsWidget::card_back_image_path() const
     GUI::ModelIndex card_back_image_index = m_last_selected_card_back;
     if (!card_back_selection.is_empty())
         card_back_image_index = card_back_selection.first();
-    return String::from_deprecated_string(static_cast<GUI::FileSystemModel const*>(m_card_back_image_view->model())->full_path(card_back_image_index)).release_value_but_fixme_should_propagate_errors();
+    return String::from_byte_string(static_cast<GUI::FileSystemModel const*>(m_card_back_image_view->model())->full_path(card_back_image_index)).release_value_but_fixme_should_propagate_errors();
 }
 
 String CardSettingsWidget::card_front_images_set_name() const
@@ -164,7 +164,7 @@ String CardSettingsWidget::card_front_images_set_name() const
     auto selected_set_name = m_card_front_images_combo_box->text();
     if (selected_set_name == "None")
         return {};
-    return MUST(String::from_deprecated_string(selected_set_name));
+    return MUST(String::from_byte_string(selected_set_name));
 }
 
 }
diff --git a/Userland/Applications/GamesSettings/CardSettingsWidget.h b/Userland/Applications/GamesSettings/CardSettingsWidget.h
index 7308f9e802a..e75dcb46152 100644
--- a/Userland/Applications/GamesSettings/CardSettingsWidget.h
+++ b/Userland/Applications/GamesSettings/CardSettingsWidget.h
@@ -35,7 +35,7 @@ private:
     String card_back_image_path() const;
     String card_front_images_set_name() const;
 
-    Vector<DeprecatedString> m_card_front_sets;
+    Vector<ByteString> m_card_front_sets;
 
     RefPtr<CardGamePreview> m_preview_frame;
     RefPtr<GUI::ColorInput> m_background_color_input;
diff --git a/Userland/Applications/GamesSettings/ChessSettingsWidget.cpp b/Userland/Applications/GamesSettings/ChessSettingsWidget.cpp
index 48177afe37e..19a63a477d4 100644
--- a/Userland/Applications/GamesSettings/ChessSettingsWidget.cpp
+++ b/Userland/Applications/GamesSettings/ChessSettingsWidget.cpp
@@ -251,12 +251,12 @@ ErrorOr<void> ChessSettingsWidget::initialize()
         TRY(m_piece_sets.try_append(entry.name));
         return IterationDecision::Continue;
     }));
-    auto piece_set_model = GUI::ItemListModel<DeprecatedString>::create(m_piece_sets);
+    auto piece_set_model = GUI::ItemListModel<ByteString>::create(m_piece_sets);
     m_piece_set_combobox->set_model(piece_set_model);
     m_piece_set_combobox->set_text(piece_set_name, GUI::AllowCallback::No);
     m_piece_set_combobox->on_change = [&](auto& value, auto&) {
         set_modified(true);
-        m_preview->set_piece_set_name(MUST(String::from_deprecated_string(value)));
+        m_preview->set_piece_set_name(MUST(String::from_byte_string(value)));
     };
 
     m_board_theme_combobox = find_descendant_of_type_named<GUI::ComboBox>("board_theme");
@@ -283,7 +283,7 @@ ErrorOr<void> ChessSettingsWidget::initialize()
         set_modified(true);
     };
 
-    m_preview->set_piece_set_name(TRY(String::from_deprecated_string(piece_set_name)));
+    m_preview->set_piece_set_name(TRY(String::from_byte_string(piece_set_name)));
     m_preview->set_dark_square_color(board_theme.dark_square_color);
     m_preview->set_light_square_color(board_theme.light_square_color);
     m_preview->set_show_coordinates(show_coordinates);
diff --git a/Userland/Applications/GamesSettings/ChessSettingsWidget.h b/Userland/Applications/GamesSettings/ChessSettingsWidget.h
index 704823b0441..26b743dbe31 100644
--- a/Userland/Applications/GamesSettings/ChessSettingsWidget.h
+++ b/Userland/Applications/GamesSettings/ChessSettingsWidget.h
@@ -28,7 +28,7 @@ private:
     ChessSettingsWidget() = default;
     ErrorOr<void> initialize();
 
-    Vector<DeprecatedString> m_piece_sets;
+    Vector<ByteString> m_piece_sets;
 
     RefPtr<GamesSettings::ChessGamePreview> m_preview;
     RefPtr<GUI::ComboBox> m_piece_set_combobox;
diff --git a/Userland/Applications/Help/History.cpp b/Userland/Applications/Help/History.cpp
index 2bbab72c9d3..6c8dc490ee4 100644
--- a/Userland/Applications/Help/History.cpp
+++ b/Userland/Applications/Help/History.cpp
@@ -16,7 +16,7 @@ void History::push(StringView history_item)
     m_current_history_item++;
 }
 
-DeprecatedString History::current()
+ByteString History::current()
 {
     if (m_current_history_item == -1)
         return {};
diff --git a/Userland/Applications/Help/History.h b/Userland/Applications/Help/History.h
index c5f56c96268..d2d2fe00d3a 100644
--- a/Userland/Applications/Help/History.h
+++ b/Userland/Applications/Help/History.h
@@ -6,13 +6,13 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 
 class History final {
 public:
     void push(StringView history_item);
-    DeprecatedString current();
+    ByteString current();
 
     void go_back();
     void go_forward();
@@ -23,6 +23,6 @@ public:
     void clear();
 
 private:
-    Vector<DeprecatedString> m_items;
+    Vector<ByteString> m_items;
     int m_current_history_item { -1 };
 };
diff --git a/Userland/Applications/Help/MainWidget.cpp b/Userland/Applications/Help/MainWidget.cpp
index 2443ec08347..0a26a5373b9 100644
--- a/Userland/Applications/Help/MainWidget.cpp
+++ b/Userland/Applications/Help/MainWidget.cpp
@@ -132,7 +132,7 @@ ErrorOr<void> MainWidget::initialize_fallibles(GUI::Window& window)
                 return;
             }
             m_history.push(path.string());
-            auto string_path = String::from_deprecated_string(path.string());
+            auto string_path = String::from_byte_string(path.string());
             if (string_path.is_error())
                 return;
             open_page(string_path.value());
@@ -156,7 +156,7 @@ ErrorOr<void> MainWidget::initialize_fallibles(GUI::Window& window)
     };
     m_web_view->on_link_hover = [this](URL const& url) {
         if (url.is_valid())
-            m_statusbar->set_text(String::from_deprecated_string(url.to_deprecated_string()).release_value_but_fixme_should_propagate_errors());
+            m_statusbar->set_text(String::from_byte_string(url.to_byte_string()).release_value_but_fixme_should_propagate_errors());
         else
             m_statusbar->set_text({});
     };
@@ -166,12 +166,12 @@ ErrorOr<void> MainWidget::initialize_fallibles(GUI::Window& window)
 
     m_go_back_action = GUI::CommonActions::make_go_back_action([this](auto&) {
         m_history.go_back();
-        open_page(MUST(String::from_deprecated_string(m_history.current())));
+        open_page(MUST(String::from_byte_string(m_history.current())));
     });
 
     m_go_forward_action = GUI::CommonActions::make_go_forward_action([this](auto&) {
         m_history.go_forward();
-        open_page(MUST(String::from_deprecated_string(m_history.current())));
+        open_page(MUST(String::from_byte_string(m_history.current())));
     });
 
     m_go_back_action->set_enabled(false);
@@ -261,7 +261,7 @@ void MainWidget::open_url(URL const& url)
                 return;
             auto title = String::formatted("{} - Help", page_and_section.value());
             if (!title.is_error())
-                window()->set_title(title.release_value().to_deprecated_string());
+                window()->set_title(title.release_value().to_byte_string());
         } else {
             window()->set_title("Help");
         }
@@ -271,7 +271,7 @@ void MainWidget::open_url(URL const& url)
 void MainWidget::open_external(URL const& url)
 {
     if (!Desktop::Launcher::open(url))
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("The link to '{}' could not be opened.", url), "Failed to open link"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(window(), ByteString::formatted("The link to '{}' could not be opened.", url), "Failed to open link"sv, GUI::MessageBox::Type::Error);
 }
 
 void MainWidget::open_page(Optional<String> const& path)
@@ -285,7 +285,7 @@ void MainWidget::open_page(Optional<String> const& path)
         return;
     }
     dbgln("open page: {}", path.value());
-    open_url(URL::create_with_url_or_path(path.value().to_deprecated_string()));
+    open_url(URL::create_with_url_or_path(path.value().to_byte_string()));
 }
 
 }
diff --git a/Userland/Applications/Help/ManualModel.cpp b/Userland/Applications/Help/ManualModel.cpp
index b0c61a8882a..941d0ec8e1b 100644
--- a/Userland/Applications/Help/ManualModel.cpp
+++ b/Userland/Applications/Help/ManualModel.cpp
@@ -183,8 +183,8 @@ GUI::Variant ManualModel::data(const GUI::ModelIndex& index, GUI::ModelRole role
             return {};
         if (auto path = page_path(index); path.has_value())
             if (auto page = page_view(path.release_value()); !page.is_error())
-                // FIXME: We already provide String, but GUI::Variant still needs DeprecatedString.
-                return DeprecatedString(page.release_value());
+                // FIXME: We already provide String, but GUI::Variant still needs ByteString.
+                return ByteString(page.release_value());
         return {};
     case GUI::ModelRole::Display:
         if (auto name = node->name(); !name.is_error())
diff --git a/Userland/Applications/Help/main.cpp b/Userland/Applications/Help/main.cpp
index c39baaa6093..d4ab1fe6965 100644
--- a/Userland/Applications/Help/main.cpp
+++ b/Userland/Applications/Help/main.cpp
@@ -31,8 +31,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::unveil("/tmp/session/%sid/portal/webcontent", "rw"));
     TRY(Core::System::unveil(nullptr, nullptr));
 
-    DeprecatedString first_query_parameter;
-    DeprecatedString second_query_parameter;
+    ByteString first_query_parameter;
+    ByteString second_query_parameter;
 
     Core::ArgsParser args_parser;
     // The actual "page query" parsing happens when we set the main widget's start page.
diff --git a/Userland/Applications/HexEditor/FindDialog.cpp b/Userland/Applications/HexEditor/FindDialog.cpp
index f7b3c715470..9e36cc1c65e 100644
--- a/Userland/Applications/HexEditor/FindDialog.cpp
+++ b/Userland/Applications/HexEditor/FindDialog.cpp
@@ -142,7 +142,7 @@ FindDialog::FindDialog(NonnullRefPtr<HexEditor::FindWidget> find_widget)
     };
 
     m_find_button->on_click = [this](auto) {
-        auto text = String::from_deprecated_string(m_text_editor->text()).release_value_but_fixme_should_propagate_errors();
+        auto text = String::from_byte_string(m_text_editor->text()).release_value_but_fixme_should_propagate_errors();
         if (!text.is_empty()) {
             m_text_value = text;
             done(ExecResult::OK);
diff --git a/Userland/Applications/HexEditor/GoToOffsetDialog.cpp b/Userland/Applications/HexEditor/GoToOffsetDialog.cpp
index 62d318264d0..ccde68295ed 100644
--- a/Userland/Applications/HexEditor/GoToOffsetDialog.cpp
+++ b/Userland/Applications/HexEditor/GoToOffsetDialog.cpp
@@ -51,14 +51,14 @@ GUI::Dialog::ExecResult GoToOffsetDialog::show(GUI::Window* parent_window, int&
 
 int GoToOffsetDialog::process_input()
 {
-    auto input_offset = String::from_deprecated_string(m_text_editor->text().trim_whitespace()).release_value_but_fixme_should_propagate_errors();
+    auto input_offset = String::from_byte_string(m_text_editor->text().trim_whitespace()).release_value_but_fixme_should_propagate_errors();
     int offset;
     auto type = m_offset_type_box->text().trim_whitespace();
     if (type == "Decimal") {
         offset = input_offset.to_number<int>().value_or(0);
     } else if (type == "Hexadecimal") {
         // FIXME: Find a better way of parsing hex to a number that doesn't require a zero terminated string
-        offset = strtol(input_offset.to_deprecated_string().characters(), nullptr, 16);
+        offset = strtol(input_offset.to_byte_string().characters(), nullptr, 16);
     } else {
         VERIFY_NOT_REACHED();
     }
diff --git a/Userland/Applications/HexEditor/HexDocument.h b/Userland/Applications/HexEditor/HexDocument.h
index 402e9b8c14d..f575feff397 100644
--- a/Userland/Applications/HexEditor/HexDocument.h
+++ b/Userland/Applications/HexEditor/HexDocument.h
@@ -95,7 +95,7 @@ public:
 
     virtual void undo() override;
     virtual void redo() override;
-    virtual DeprecatedString action_text() const override { return "Update cell"; }
+    virtual ByteString action_text() const override { return "Update cell"; }
 
     virtual bool merge_with(GUI::Command const& other) override;
 
diff --git a/Userland/Applications/HexEditor/HexEditor.cpp b/Userland/Applications/HexEditor/HexEditor.cpp
index 1ca9a0a788b..d792552dd2e 100644
--- a/Userland/Applications/HexEditor/HexEditor.cpp
+++ b/Userland/Applications/HexEditor/HexEditor.cpp
@@ -9,8 +9,8 @@
 
 #include "HexEditor.h"
 #include "SearchResultsModel.h"
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <AK/ScopeGuard.h>
 #include <AK/StringBuilder.h>
@@ -180,7 +180,7 @@ bool HexEditor::copy_selected_hex_to_clipboard()
     for (size_t i = m_selection_start; i < m_selection_end; i++)
         output_string_builder.appendff("{:02X} ", m_document->get(i).value);
 
-    GUI::Clipboard::the().set_plain_text(output_string_builder.to_deprecated_string());
+    GUI::Clipboard::the().set_plain_text(output_string_builder.to_byte_string());
     return true;
 }
 
@@ -193,7 +193,7 @@ bool HexEditor::copy_selected_text_to_clipboard()
     for (size_t i = m_selection_start; i < m_selection_end; i++)
         output_string_builder.append(isprint(m_document->get(i).value) ? m_document->get(i).value : '.');
 
-    GUI::Clipboard::the().set_plain_text(output_string_builder.to_deprecated_string());
+    GUI::Clipboard::the().set_plain_text(output_string_builder.to_byte_string());
     return true;
 }
 
@@ -216,7 +216,7 @@ bool HexEditor::copy_selected_hex_to_clipboard_as_c_code()
     }
     output_string_builder.append("\n};\n"sv);
 
-    GUI::Clipboard::the().set_plain_text(output_string_builder.to_deprecated_string());
+    GUI::Clipboard::the().set_plain_text(output_string_builder.to_byte_string());
     return true;
 }
 
@@ -490,7 +490,7 @@ void HexEditor::keydown_event(GUI::KeyEvent& event)
             result = text_mode_keydown_event(event);
         }
         if (result.is_error())
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("{}", result.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("{}", result.error()));
     }
 
     event.ignore();
diff --git a/Userland/Applications/HexEditor/HexEditorWidget.cpp b/Userland/Applications/HexEditor/HexEditorWidget.cpp
index d91fec4fceb..2a11bb1a8f2 100644
--- a/Userland/Applications/HexEditor/HexEditorWidget.cpp
+++ b/Userland/Applications/HexEditor/HexEditorWidget.cpp
@@ -112,7 +112,7 @@ ErrorOr<void> HexEditorWidget::setup()
             }
 
             if (auto error = m_editor->open_new_file(file_size.value()); error.is_error()) {
-                GUI::MessageBox::show(window(), DeprecatedString::formatted("Unable to open new file: {}"sv, error.error()), "Error"sv, GUI::MessageBox::Type::Error);
+                GUI::MessageBox::show(window(), ByteString::formatted("Unable to open new file: {}"sv, error.error()), "Error"sv, GUI::MessageBox::Type::Error);
                 return;
             }
 
@@ -137,7 +137,7 @@ ErrorOr<void> HexEditorWidget::setup()
             return m_save_as_action->activate();
 
         if (auto result = m_editor->save(); result.is_error()) {
-            GUI::MessageBox::show(window(), DeprecatedString::formatted("Unable to save file: {}\n"sv, result.error()), "Error"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(window(), ByteString::formatted("Unable to save file: {}\n"sv, result.error()), "Error"sv, GUI::MessageBox::Type::Error);
         } else {
             window()->set_modified(false);
             m_editor->update();
@@ -151,7 +151,7 @@ ErrorOr<void> HexEditorWidget::setup()
             return;
         auto file = response.release_value();
         if (auto result = m_editor->save_as(file.release_stream()); result.is_error()) {
-            GUI::MessageBox::show(window(), DeprecatedString::formatted("Unable to save file: {}\n"sv, result.error()), "Error"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(window(), ByteString::formatted("Unable to save file: {}\n"sv, result.error()), "Error"sv, GUI::MessageBox::Type::Error);
             return;
         }
 
@@ -180,11 +180,11 @@ ErrorOr<void> HexEditorWidget::setup()
                 m_search_results->update();
 
                 if (matches.is_empty()) {
-                    GUI::MessageBox::show(window(), DeprecatedString::formatted("Pattern \"{}\" not found in this file", m_search_text), "Not Found"sv, GUI::MessageBox::Type::Warning);
+                    GUI::MessageBox::show(window(), ByteString::formatted("Pattern \"{}\" not found in this file", m_search_text), "Not Found"sv, GUI::MessageBox::Type::Warning);
                     return;
                 }
 
-                GUI::MessageBox::show(window(), DeprecatedString::formatted("Found {} matches for \"{}\" in this file", matches.size(), m_search_text), DeprecatedString::formatted("{} Matches", matches.size()), GUI::MessageBox::Type::Warning);
+                GUI::MessageBox::show(window(), ByteString::formatted("Found {} matches for \"{}\" in this file", matches.size(), m_search_text), ByteString::formatted("{} Matches", matches.size()), GUI::MessageBox::Type::Warning);
                 set_search_results_visible(true);
             } else {
                 bool same_buffers = false;
@@ -196,7 +196,7 @@ ErrorOr<void> HexEditorWidget::setup()
                 auto result = m_editor->find_and_highlight(m_search_buffer, same_buffers ? last_found_index() : 0);
 
                 if (!result.has_value()) {
-                    GUI::MessageBox::show(window(), DeprecatedString::formatted("Pattern \"{}\" not found in this file", m_search_text), "Not Found"sv, GUI::MessageBox::Type::Warning);
+                    GUI::MessageBox::show(window(), ByteString::formatted("Pattern \"{}\" not found in this file", m_search_text), "Not Found"sv, GUI::MessageBox::Type::Warning);
                     return;
                 }
 
@@ -252,7 +252,7 @@ ErrorOr<void> HexEditorWidget::setup()
             auto fill_byte = strtol(value.bytes_as_string_view().characters_without_null_termination(), nullptr, 16);
             auto result = m_editor->fill_selection(fill_byte);
             if (result.is_error())
-                GUI::MessageBox::show_error(window(), DeprecatedString::formatted("{}", result.error()));
+                GUI::MessageBox::show_error(window(), ByteString::formatted("{}", result.error()));
         }
     });
     m_fill_selection_action->set_enabled(false);
@@ -464,7 +464,7 @@ ErrorOr<void> HexEditorWidget::initialize_menubar(GUI::Window& window)
 
         auto result = m_editor->find_and_highlight(m_search_buffer, last_found_index());
         if (!result.has_value()) {
-            GUI::MessageBox::show(&window, DeprecatedString::formatted("No more matches for \"{}\" found in this file", m_search_text), "Not Found"sv, GUI::MessageBox::Type::Warning);
+            GUI::MessageBox::show(&window, ByteString::formatted("No more matches for \"{}\" found in this file", m_search_text), "Not Found"sv, GUI::MessageBox::Type::Warning);
             return;
         }
         m_editor->update();
@@ -512,7 +512,7 @@ ErrorOr<void> HexEditorWidget::initialize_menubar(GUI::Window& window)
     m_bytes_per_row_actions.set_exclusive(true);
     auto bytes_per_row_menu = view_menu->add_submenu("Bytes per &Row"_string);
     for (int i = 8; i <= 32; i += 8) {
-        auto action = GUI::Action::create_checkable(DeprecatedString::number(i), [this, i](auto&) {
+        auto action = GUI::Action::create_checkable(ByteString::number(i), [this, i](auto&) {
             m_editor->set_bytes_per_row(i);
             m_editor->update();
             Config::write_i32("HexEditor"sv, "Layout"sv, "BytesPerRow"sv, i);
@@ -582,14 +582,14 @@ void HexEditorWidget::update_title()
     else
         builder.append(m_path);
     builder.append("[*] - Hex Editor"sv);
-    window()->set_title(builder.to_deprecated_string());
+    window()->set_title(builder.to_byte_string());
 }
 
 void HexEditorWidget::open_file(String const& filename, NonnullOwnPtr<Core::File> file)
 {
     window()->set_modified(false);
     m_editor->open_file(move(file));
-    set_path(filename.to_deprecated_string());
+    set_path(filename.to_byte_string());
     GUI::Application::the()->set_most_recently_open_file(filename);
 }
 
diff --git a/Userland/Applications/HexEditor/HexEditorWidget.h b/Userland/Applications/HexEditor/HexEditorWidget.h
index 500e7592900..53d6dc26f10 100644
--- a/Userland/Applications/HexEditor/HexEditorWidget.h
+++ b/Userland/Applications/HexEditor/HexEditorWidget.h
@@ -46,9 +46,9 @@ private:
     virtual void drop_event(GUI::DropEvent&) override;
 
     RefPtr<HexEditor> m_editor;
-    DeprecatedString m_path;
-    DeprecatedString m_name;
-    DeprecatedString m_extension;
+    ByteString m_path;
+    ByteString m_name;
+    ByteString m_extension;
 
     int m_goto_history { 0 };
     String m_search_text;
diff --git a/Userland/Applications/HexEditor/SearchResultsModel.h b/Userland/Applications/HexEditor/SearchResultsModel.h
index afe6ccb37c8..29f4f6a1506 100644
--- a/Userland/Applications/HexEditor/SearchResultsModel.h
+++ b/Userland/Applications/HexEditor/SearchResultsModel.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Hex.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/Utf8View.h>
@@ -63,7 +63,7 @@ public:
             auto& match = m_matches.at(index.row());
             switch (index.column()) {
             case Column::Offset:
-                return DeprecatedString::formatted("{:#08X}", match.offset);
+                return ByteString::formatted("{:#08X}", match.offset);
             case Column::Value: {
                 Utf8View utf8_view(match.value);
                 if (!utf8_view.validate())
diff --git a/Userland/Applications/HexEditor/ValueInspectorModel.h b/Userland/Applications/HexEditor/ValueInspectorModel.h
index da5f0ebf213..7fa3bc44063 100644
--- a/Userland/Applications/HexEditor/ValueInspectorModel.h
+++ b/Userland/Applications/HexEditor/ValueInspectorModel.h
@@ -121,7 +121,7 @@ public:
         if (role == GUI::ModelRole::Display) {
             switch (index.column()) {
             case Column::Type:
-                return inspector_value_type_to_string(static_cast<ValueType>(index.row())).to_deprecated_string();
+                return inspector_value_type_to_string(static_cast<ValueType>(index.row())).to_byte_string();
             case Column::Value:
                 return m_values.at(index.row());
             }
diff --git a/Userland/Applications/ImageViewer/ViewWidget.cpp b/Userland/Applications/ImageViewer/ViewWidget.cpp
index dea7573f3d7..f3ae54932ca 100644
--- a/Userland/Applications/ImageViewer/ViewWidget.cpp
+++ b/Userland/Applications/ImageViewer/ViewWidget.cpp
@@ -118,14 +118,14 @@ bool ViewWidget::is_previous_available() const
 
 // FIXME: Convert to `String` & use LibFileSystemAccessClient + `Core::System::unveil(nullptr, nullptr)`
 //        - Converting to String is not super-trivial due to the LexicalPath usage, while we can do a bunch of
-//          String::from_deprecated_string() and String.to_deprecated_string(), it is quite ugly to read and
+//          String::from_byte_string() and String.to_byte_string(), it is quite ugly to read and
 //          probably not the best approach.
 //
 //        - If we go full-unveil (`Core::System::unveil(nullptr, nullptr)`) this functionality does not work,
 //          we can not access the list of contents of a directory through LibFileSystemAccessClient at the moment.
-Vector<DeprecatedString> ViewWidget::load_files_from_directory(DeprecatedString const& path) const
+Vector<ByteString> ViewWidget::load_files_from_directory(ByteString const& path) const
 {
-    Vector<DeprecatedString> files_in_directory;
+    Vector<ByteString> files_in_directory;
 
     auto current_dir = LexicalPath(path).parent().string();
     // FIXME: Propagate errors
@@ -141,8 +141,8 @@ Vector<DeprecatedString> ViewWidget::load_files_from_directory(DeprecatedString
 void ViewWidget::set_path(String const& path)
 {
     m_path = path;
-    m_files_in_same_dir = load_files_from_directory(path.to_deprecated_string());
-    m_current_index = m_files_in_same_dir.find_first_index(path.to_deprecated_string());
+    m_files_in_same_dir = load_files_from_directory(path.to_byte_string());
+    m_current_index = m_files_in_same_dir.find_first_index(path.to_byte_string());
 }
 
 void ViewWidget::navigate(Directions direction)
diff --git a/Userland/Applications/ImageViewer/ViewWidget.h b/Userland/Applications/ImageViewer/ViewWidget.h
index 44cff4853a7..e509cb8efb7 100644
--- a/Userland/Applications/ImageViewer/ViewWidget.h
+++ b/Userland/Applications/ImageViewer/ViewWidget.h
@@ -138,7 +138,7 @@ private:
 
     void set_image(Image const* image);
     void animate();
-    Vector<DeprecatedString> load_files_from_directory(DeprecatedString const& path) const;
+    Vector<ByteString> load_files_from_directory(ByteString const& path) const;
     ErrorOr<void> try_open_file(String const&, Core::File&);
 
     String m_path;
@@ -162,7 +162,7 @@ private:
 
     int m_toolbar_height { 28 };
     bool m_scaled_for_first_image { false };
-    Vector<DeprecatedString> m_files_in_same_dir;
+    Vector<ByteString> m_files_in_same_dir;
     Optional<size_t> m_current_index;
     Gfx::Painter::ScalingMode m_scaling_mode { Gfx::Painter::ScalingMode::NearestNeighbor };
 };
diff --git a/Userland/Applications/ImageViewer/main.cpp b/Userland/Applications/ImageViewer/main.cpp
index a88f9b8fb58..3b2c75897cd 100644
--- a/Userland/Applications/ImageViewer/main.cpp
+++ b/Userland/Applications/ImageViewer/main.cpp
@@ -82,7 +82,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             return;
         }
 
-        window->set_title(DeprecatedString::formatted("{} {} {}% - Image Viewer", widget.path(), widget.image()->size().to_deprecated_string(), (int)(scale * 100)));
+        window->set_title(ByteString::formatted("{} {} {}% - Image Viewer", widget.path(), widget.image()->size().to_byte_string(), (int)(scale * 100)));
 
         if (!widget.scaled_for_first_image()) {
             widget.set_scaled_for_first_image(true);
@@ -140,7 +140,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 return;
 
             auto msgbox_result = GUI::MessageBox::show(window,
-                DeprecatedString::formatted("Are you sure you want to delete {}?", path),
+                ByteString::formatted("Are you sure you want to delete {}?", path),
                 "Confirm Deletion"sv,
                 GUI::MessageBox::Type::Warning,
                 GUI::MessageBox::InputType::OKCancel);
@@ -151,7 +151,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             auto unlinked_or_error = Core::System::unlink(widget.path());
             if (unlinked_or_error.is_error()) {
                 GUI::MessageBox::show(window,
-                    DeprecatedString::formatted("unlink({}) failed: {}", path, unlinked_or_error.error()),
+                    ByteString::formatted("unlink({}) failed: {}", path, unlinked_or_error.error()),
                     "Delete Failed"sv,
                     GUI::MessageBox::Type::Error);
 
@@ -188,7 +188,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         [&](auto&) {
             if (!GUI::Desktop::the().set_wallpaper(widget.image()->bitmap(GUI::Desktop::the().rect().size()).release_value_but_fixme_should_propagate_errors(), widget.path())) {
                 GUI::MessageBox::show(window,
-                    DeprecatedString::formatted("set_wallpaper({}) failed", widget.path()),
+                    ByteString::formatted("set_wallpaper({}) failed", widget.path()),
                     "Could not set wallpaper"sv,
                     GUI::MessageBox::Type::Error);
             }
diff --git a/Userland/Applications/KeyboardMapper/KeyPositions.h b/Userland/Applications/KeyboardMapper/KeyPositions.h
index 9a976be5855..b5ae6eef6d6 100644
--- a/Userland/Applications/KeyboardMapper/KeyPositions.h
+++ b/Userland/Applications/KeyboardMapper/KeyPositions.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 
 struct KeyPosition {
     u32 scancode;
@@ -16,7 +16,7 @@ struct KeyPosition {
     int height;
     bool enabled;
     int map_index;
-    DeprecatedString name;
+    ByteString name;
 };
 
 #define KEY_COUNT 63
diff --git a/Userland/Applications/KeyboardMapper/KeyboardMapperWidget.cpp b/Userland/Applications/KeyboardMapper/KeyboardMapperWidget.cpp
index 17620e05dbf..ba9756ef46d 100644
--- a/Userland/Applications/KeyboardMapper/KeyboardMapperWidget.cpp
+++ b/Userland/Applications/KeyboardMapper/KeyboardMapperWidget.cpp
@@ -51,7 +51,7 @@ void KeyboardMapperWidget::create_frame()
 
         auto& tmp_button = main_widget.add<KeyButton>();
         tmp_button.set_relative_rect(rect);
-        tmp_button.set_text(String::from_deprecated_string(keys[i].name).release_value_but_fixme_should_propagate_errors());
+        tmp_button.set_text(String::from_byte_string(keys[i].name).release_value_but_fixme_should_propagate_errors());
         tmp_button.set_enabled(keys[i].enabled);
 
         tmp_button.on_click = [this, &tmp_button]() {
@@ -125,7 +125,7 @@ u32* KeyboardMapperWidget::map_from_name(const StringView map_name)
     return map;
 }
 
-ErrorOr<void> KeyboardMapperWidget::load_map_from_file(DeprecatedString const& filename)
+ErrorOr<void> KeyboardMapperWidget::load_map_from_file(ByteString const& filename)
 {
     auto character_map = TRY(Keyboard::CharacterMapFile::load_from_file(filename));
 
@@ -147,7 +147,7 @@ ErrorOr<void> KeyboardMapperWidget::load_map_from_system()
 {
     auto character_map = TRY(Keyboard::CharacterMap::fetch_system_map());
 
-    m_filename = DeprecatedString::formatted("/res/keymaps/{}.json", character_map.character_map_name());
+    m_filename = ByteString::formatted("/res/keymaps/{}.json", character_map.character_map_name());
     m_character_map = character_map.character_map_data();
     set_current_map("map");
 
@@ -169,14 +169,14 @@ ErrorOr<void> KeyboardMapperWidget::save_to_file(StringView filename)
 {
     JsonObject map_json;
 
-    auto add_array = [&](DeprecatedString name, u32* values) {
+    auto add_array = [&](ByteString name, u32* values) {
         JsonArray items;
         for (int i = 0; i < 90; i++) {
             StringBuilder sb;
             if (values[i])
                 sb.append_code_point(values[i]);
 
-            JsonValue val(sb.to_deprecated_string());
+            JsonValue val(sb.to_byte_string());
             items.must_append(move(val));
         }
         map_json.set(name, move(items));
@@ -189,7 +189,7 @@ ErrorOr<void> KeyboardMapperWidget::save_to_file(StringView filename)
     add_array("shift_altgr_map", m_character_map.shift_altgr_map);
 
     // Write to file.
-    DeprecatedString file_content = map_json.to_deprecated_string();
+    ByteString file_content = map_json.to_byte_string();
     auto file = TRY(Core::File::open(filename, Core::File::OpenMode::Write));
     TRY(file->write_until_depleted(file_content.bytes()));
     file->close();
@@ -234,7 +234,7 @@ void KeyboardMapperWidget::keyup_event(GUI::KeyEvent& event)
     }
 }
 
-void KeyboardMapperWidget::set_current_map(const DeprecatedString current_map)
+void KeyboardMapperWidget::set_current_map(const ByteString current_map)
 {
     m_current_map_name = current_map;
     u32* map = map_from_name(m_current_map_name);
@@ -259,7 +259,7 @@ void KeyboardMapperWidget::update_window_title()
     sb.append(m_filename);
     sb.append("[*] - Keyboard Mapper"sv);
 
-    window()->set_title(sb.to_deprecated_string());
+    window()->set_title(sb.to_byte_string());
 }
 
 void KeyboardMapperWidget::show_error_to_user(Error error)
diff --git a/Userland/Applications/KeyboardMapper/KeyboardMapperWidget.h b/Userland/Applications/KeyboardMapper/KeyboardMapperWidget.h
index fcd14be56ef..c46af2a14d7 100644
--- a/Userland/Applications/KeyboardMapper/KeyboardMapperWidget.h
+++ b/Userland/Applications/KeyboardMapper/KeyboardMapperWidget.h
@@ -18,7 +18,7 @@ public:
     virtual ~KeyboardMapperWidget() override = default;
 
     void create_frame();
-    ErrorOr<void> load_map_from_file(DeprecatedString const&);
+    ErrorOr<void> load_map_from_file(ByteString const&);
     ErrorOr<void> load_map_from_system();
     ErrorOr<void> save();
     ErrorOr<void> save_to_file(StringView);
@@ -31,7 +31,7 @@ protected:
     virtual void keydown_event(GUI::KeyEvent&) override;
     virtual void keyup_event(GUI::KeyEvent&) override;
 
-    void set_current_map(const DeprecatedString);
+    void set_current_map(const ByteString);
     void update_window_title();
 
 private:
@@ -43,8 +43,8 @@ private:
     u32* map_from_name(const StringView map_name);
     void update_modifier_radio_buttons(GUI::KeyEvent&);
 
-    DeprecatedString m_filename;
+    ByteString m_filename;
     Keyboard::CharacterMapData m_character_map;
-    DeprecatedString m_current_map_name;
+    ByteString m_current_map_name;
     bool m_automatic_modifier { false };
 };
diff --git a/Userland/Applications/KeyboardMapper/main.cpp b/Userland/Applications/KeyboardMapper/main.cpp
index de1c6e62635..6941265a17b 100644
--- a/Userland/Applications/KeyboardMapper/main.cpp
+++ b/Userland/Applications/KeyboardMapper/main.cpp
@@ -48,7 +48,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             if (!keyboard_mapper_widget->request_close())
                 return;
 
-            Optional<DeprecatedString> path = GUI::FilePicker::get_open_filepath(window, "Open"sv, "/res/keymaps/"sv);
+            Optional<ByteString> path = GUI::FilePicker::get_open_filepath(window, "Open"sv, "/res/keymaps/"sv);
             if (!path.has_value())
                 return;
 
@@ -63,8 +63,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         });
 
     auto save_as_action = GUI::CommonActions::make_save_as_action([&](auto&) {
-        DeprecatedString name = "Unnamed";
-        Optional<DeprecatedString> save_path = GUI::FilePicker::get_save_filepath(window, name, "json");
+        ByteString name = "Unnamed";
+        Optional<ByteString> save_path = GUI::FilePicker::get_save_filepath(window, name, "json");
         if (!save_path.has_value())
             return;
 
diff --git a/Userland/Applications/KeyboardSettings/KeyboardSettingsWidget.cpp b/Userland/Applications/KeyboardSettings/KeyboardSettingsWidget.cpp
index 2f3fe76d936..755fee69991 100644
--- a/Userland/Applications/KeyboardSettings/KeyboardSettingsWidget.cpp
+++ b/Userland/Applications/KeyboardSettings/KeyboardSettingsWidget.cpp
@@ -34,7 +34,7 @@ class KeymapSelectionDialog final : public GUI::Dialog {
 public:
     virtual ~KeymapSelectionDialog() override = default;
 
-    static DeprecatedString select_keymap(Window* parent_window, Vector<DeprecatedString> const& selected_keymaps)
+    static ByteString select_keymap(Window* parent_window, Vector<ByteString> const& selected_keymaps)
     {
         auto dialog = KeymapSelectionDialog::construct(parent_window, selected_keymaps);
         dialog->set_title("Add a keymap");
@@ -43,13 +43,13 @@ public:
             return dialog->selected_keymap();
         }
 
-        return DeprecatedString::empty();
+        return ByteString::empty();
     }
 
-    DeprecatedString selected_keymap() { return m_selected_keymap; }
+    ByteString selected_keymap() { return m_selected_keymap; }
 
 private:
-    KeymapSelectionDialog(Window* parent_window, Vector<DeprecatedString> const& selected_keymaps)
+    KeymapSelectionDialog(Window* parent_window, Vector<ByteString> const& selected_keymaps)
         : Dialog(parent_window)
     {
         auto widget = set_main_widget<GUI::Widget>();
@@ -68,7 +68,7 @@ private:
         });
 
         if (iterator_result.is_error()) {
-            GUI::MessageBox::show(nullptr, DeprecatedString::formatted("Error on reading mapping file list: {}", iterator_result.error()), "Keyboard settings"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(nullptr, ByteString::formatted("Error on reading mapping file list: {}", iterator_result.error()), "Keyboard settings"sv, GUI::MessageBox::Type::Error);
             GUI::Application::the()->quit(-1);
         }
 
@@ -78,7 +78,7 @@ private:
 
         m_keymaps_combobox = *widget->find_descendant_of_type_named<GUI::ComboBox>("keymaps_combobox");
         m_keymaps_combobox->set_only_allow_values_from_model(true);
-        m_keymaps_combobox->set_model(*GUI::ItemListModel<DeprecatedString>::create(m_character_map_files));
+        m_keymaps_combobox->set_model(*GUI::ItemListModel<ByteString>::create(m_character_map_files));
         m_keymaps_combobox->set_selected_index(0);
 
         m_keymaps_combobox->on_change = [&](auto& keymap, auto) {
@@ -97,8 +97,8 @@ private:
     }
 
     RefPtr<GUI::ComboBox> m_keymaps_combobox;
-    Vector<DeprecatedString> m_character_map_files;
-    DeprecatedString m_selected_keymap;
+    Vector<ByteString> m_character_map_files;
+    ByteString m_selected_keymap;
 };
 
 class KeymapModel final : public GUI::Model {
@@ -110,7 +110,7 @@ public:
 
     GUI::Variant data(GUI::ModelIndex const& index, GUI::ModelRole role) const override
     {
-        DeprecatedString const& data = m_data.at(index.row());
+        ByteString const& data = m_data.at(index.row());
         if (role == GUI::ModelRole::Font && data == m_active_keymap)
             return Gfx::FontDatabase::default_font().bold_variant();
 
@@ -123,30 +123,30 @@ public:
         invalidate();
     }
 
-    void add_keymap(DeprecatedString const& keymap)
+    void add_keymap(ByteString const& keymap)
     {
         m_data.append(keymap);
         invalidate();
     }
 
-    void set_active_keymap(DeprecatedString const& keymap)
+    void set_active_keymap(ByteString const& keymap)
     {
         m_active_keymap = keymap;
         invalidate();
     }
 
-    DeprecatedString const& active_keymap() { return m_active_keymap; }
+    ByteString const& active_keymap() { return m_active_keymap; }
 
-    DeprecatedString const& keymap_at(size_t index)
+    ByteString const& keymap_at(size_t index)
     {
         return m_data[index];
     }
 
-    Vector<DeprecatedString> const& keymaps() const { return m_data; }
+    Vector<ByteString> const& keymaps() const { return m_data; }
 
 private:
-    Vector<DeprecatedString> m_data;
-    DeprecatedString m_active_keymap;
+    Vector<ByteString> m_data;
+    ByteString m_active_keymap;
 };
 
 ErrorOr<NonnullRefPtr<KeyboardSettingsWidget>> KeyboardSettingsWidget::try_create()
@@ -165,7 +165,7 @@ ErrorOr<void> KeyboardSettingsWidget::setup()
     auto json = TRY(JsonValue::from_string(keymap));
     auto const& keymap_object = json.as_object();
     VERIFY(keymap_object.has("keymap"sv));
-    m_initial_active_keymap = keymap_object.get_deprecated_string("keymap"sv).value();
+    m_initial_active_keymap = keymap_object.get_byte_string("keymap"sv).value();
     dbgln("KeyboardSettings thinks the current keymap is: {}", m_initial_active_keymap);
 
     auto mapper_config(TRY(Core::ConfigFile::open("/etc/Keyboard.ini")));
@@ -265,7 +265,7 @@ ErrorOr<void> KeyboardSettingsWidget::setup()
     m_caps_lock_checkbox = find_descendant_of_type_named<GUI::CheckBox>("caps_lock_remapped_to_ctrl_checkbox");
     auto caps_lock_is_remapped = read_caps_lock_to_ctrl_sys_variable();
     if (caps_lock_is_remapped.is_error()) {
-        auto error_message = DeprecatedString::formatted("Could not determine if Caps Lock is remapped to Ctrl: {}", caps_lock_is_remapped.error());
+        auto error_message = ByteString::formatted("Could not determine if Caps Lock is remapped to Ctrl: {}", caps_lock_is_remapped.error());
         GUI::MessageBox::show_error(window(), error_message);
     } else {
         m_caps_lock_checkbox->set_checked(caps_lock_is_remapped.value());
@@ -305,9 +305,9 @@ void KeyboardSettingsWidget::apply_settings()
     write_caps_lock_to_ctrl_sys_variable(m_caps_lock_checkbox->is_checked());
 }
 
-void KeyboardSettingsWidget::set_keymaps(Vector<DeprecatedString> const& keymaps, DeprecatedString const& active_keymap)
+void KeyboardSettingsWidget::set_keymaps(Vector<ByteString> const& keymaps, ByteString const& active_keymap)
 {
-    auto keymaps_string = DeprecatedString::join(',', keymaps);
+    auto keymaps_string = ByteString::join(',', keymaps);
     GUI::Process::spawn_or_show_error(window(), "/bin/keymap"sv, Array { "-s", keymaps_string.characters(), "-m", active_keymap.characters() });
 }
 
@@ -316,7 +316,7 @@ void KeyboardSettingsWidget::write_caps_lock_to_ctrl_sys_variable(bool caps_lock
     if (getuid() != 0)
         return;
 
-    auto write_command = DeprecatedString::formatted("caps_lock_to_ctrl={}", caps_lock_to_ctrl ? "1" : "0");
+    auto write_command = ByteString::formatted("caps_lock_to_ctrl={}", caps_lock_to_ctrl ? "1" : "0");
     GUI::Process::spawn_or_show_error(window(), "/bin/sysctl"sv, Array { "-w", write_command.characters() });
 }
 
diff --git a/Userland/Applications/KeyboardSettings/KeyboardSettingsWidget.h b/Userland/Applications/KeyboardSettings/KeyboardSettingsWidget.h
index 6281857ff0d..15eb7c4a7ed 100644
--- a/Userland/Applications/KeyboardSettings/KeyboardSettingsWidget.h
+++ b/Userland/Applications/KeyboardSettings/KeyboardSettingsWidget.h
@@ -29,14 +29,14 @@ private:
     KeyboardSettingsWidget() = default;
     ErrorOr<void> setup();
 
-    void set_keymaps(Vector<DeprecatedString> const& keymaps, DeprecatedString const& active_keymap);
+    void set_keymaps(Vector<ByteString> const& keymaps, ByteString const& active_keymap);
 
     void write_caps_lock_to_ctrl_sys_variable(bool);
     ErrorOr<bool> read_caps_lock_to_ctrl_sys_variable();
 
-    Vector<DeprecatedString> m_initial_keymap_list;
+    Vector<ByteString> m_initial_keymap_list;
 
-    DeprecatedString m_initial_active_keymap;
+    ByteString m_initial_active_keymap;
 
     RefPtr<GUI::ListView> m_selected_keymaps_listview;
     RefPtr<GUI::Label> m_active_keymap_label;
diff --git a/Userland/Applications/Magnifier/main.cpp b/Userland/Applications/Magnifier/main.cpp
index 7829b5dd115..1157e24df88 100644
--- a/Userland/Applications/Magnifier/main.cpp
+++ b/Userland/Applications/Magnifier/main.cpp
@@ -63,13 +63,13 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto file_menu = window->add_menu("&File"_string);
     file_menu->add_action(GUI::CommonActions::make_save_as_action([&](auto&) {
-        AK::DeprecatedString filename = "file for saving";
+        AK::ByteString filename = "file for saving";
         auto do_save = [&]() -> ErrorOr<void> {
             auto response = FileSystemAccessClient::Client::the().save_file(window, "Capture", "png");
             if (response.is_error())
                 return {};
             auto file = response.value().release_stream();
-            auto path = AK::LexicalPath(response.value().filename().to_deprecated_string());
+            auto path = AK::LexicalPath(response.value().filename().to_byte_string());
             filename = path.basename();
             auto encoded = TRY(dump_bitmap(magnifier->current_bitmap(), path.extension()));
 
@@ -128,7 +128,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             };
             dialog->set_color_has_alpha_channel(true);
             if (dialog->exec() == GUI::Dialog::ExecResult::OK) {
-                Config::write_string("Magnifier"sv, "Grid"sv, "Color"sv, dialog->color().to_deprecated_string());
+                Config::write_string("Magnifier"sv, "Grid"sv, "Color"sv, dialog->color().to_byte_string());
             }
         });
     {
diff --git a/Userland/Applications/Mail/AccountHolder.cpp b/Userland/Applications/Mail/AccountHolder.cpp
index cfd5a177543..e6ff75167e1 100644
--- a/Userland/Applications/Mail/AccountHolder.cpp
+++ b/Userland/Applications/Mail/AccountHolder.cpp
@@ -12,7 +12,7 @@ AccountHolder::AccountHolder()
     m_mailbox_tree_model = MailboxTreeModel::create(*this);
 }
 
-void AccountHolder::add_account_with_name_and_mailboxes(DeprecatedString name, Vector<IMAP::ListItem> const& mailboxes)
+void AccountHolder::add_account_with_name_and_mailboxes(ByteString name, Vector<IMAP::ListItem> const& mailboxes)
 {
     auto account = AccountNode::create(move(name));
 
diff --git a/Userland/Applications/Mail/AccountHolder.h b/Userland/Applications/Mail/AccountHolder.h
index 4fa5bd44dc9..ea69facad72 100644
--- a/Userland/Applications/Mail/AccountHolder.h
+++ b/Userland/Applications/Mail/AccountHolder.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include "MailboxTreeModel.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/RefCounted.h>
 #include <LibIMAP/Objects.h>
 
@@ -21,7 +21,7 @@ class MailboxNode;
 
 class AccountNode final : public BaseNode {
 public:
-    static NonnullRefPtr<AccountNode> create(DeprecatedString name)
+    static NonnullRefPtr<AccountNode> create(ByteString name)
     {
         return adopt_ref(*new AccountNode(move(name)));
     }
@@ -34,21 +34,21 @@ public:
     }
 
     Vector<NonnullRefPtr<MailboxNode>> const& mailboxes() const { return m_mailboxes; }
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
 
 private:
-    explicit AccountNode(DeprecatedString name)
+    explicit AccountNode(ByteString name)
         : m_name(move(name))
     {
     }
 
-    DeprecatedString m_name;
+    ByteString m_name;
     Vector<NonnullRefPtr<MailboxNode>> m_mailboxes;
 };
 
 class MailboxNode final : public BaseNode {
 public:
-    static NonnullRefPtr<MailboxNode> create(AccountNode const& associated_account, IMAP::ListItem const& mailbox, DeprecatedString display_name)
+    static NonnullRefPtr<MailboxNode> create(AccountNode const& associated_account, IMAP::ListItem const& mailbox, ByteString display_name)
     {
         return adopt_ref(*new MailboxNode(associated_account, mailbox, move(display_name)));
     }
@@ -56,8 +56,8 @@ public:
     virtual ~MailboxNode() override = default;
 
     AccountNode const& associated_account() const { return m_associated_account; }
-    DeprecatedString const& select_name() const { return m_mailbox.name; }
-    DeprecatedString const& display_name() const { return m_display_name; }
+    ByteString const& select_name() const { return m_mailbox.name; }
+    ByteString const& display_name() const { return m_display_name; }
     IMAP::ListItem const& mailbox() const { return m_mailbox; }
 
     bool has_parent() const { return m_parent; }
@@ -69,7 +69,7 @@ public:
     void add_child(NonnullRefPtr<MailboxNode> child) { m_children.append(child); }
 
 private:
-    MailboxNode(AccountNode const& associated_account, IMAP::ListItem const& mailbox, DeprecatedString display_name)
+    MailboxNode(AccountNode const& associated_account, IMAP::ListItem const& mailbox, ByteString display_name)
         : m_associated_account(associated_account)
         , m_mailbox(mailbox)
         , m_display_name(move(display_name))
@@ -78,7 +78,7 @@ private:
 
     AccountNode const& m_associated_account;
     IMAP::ListItem m_mailbox;
-    DeprecatedString m_display_name;
+    ByteString m_display_name;
 
     Vector<NonnullRefPtr<MailboxNode>> m_children;
     RefPtr<MailboxNode> m_parent;
@@ -93,7 +93,7 @@ public:
         return adopt_own(*new AccountHolder());
     }
 
-    void add_account_with_name_and_mailboxes(DeprecatedString, Vector<IMAP::ListItem> const&);
+    void add_account_with_name_and_mailboxes(ByteString, Vector<IMAP::ListItem> const&);
 
     Vector<NonnullRefPtr<AccountNode>> const& accounts() const { return m_accounts; }
     MailboxTreeModel& mailbox_tree_model() { return *m_mailbox_tree_model; }
diff --git a/Userland/Applications/Mail/InboxModel.h b/Userland/Applications/Mail/InboxModel.h
index 91a4899f730..bc6dc607671 100644
--- a/Userland/Applications/Mail/InboxModel.h
+++ b/Userland/Applications/Mail/InboxModel.h
@@ -12,9 +12,9 @@
 
 struct InboxEntry {
     u32 sequence_number;
-    DeprecatedString date;
-    DeprecatedString from;
-    DeprecatedString subject;
+    ByteString date;
+    ByteString from;
+    ByteString subject;
     bool seen;
 };
 
diff --git a/Userland/Applications/Mail/MailWidget.cpp b/Userland/Applications/Mail/MailWidget.cpp
index 5ac793d4f4d..996de3277e8 100644
--- a/Userland/Applications/Mail/MailWidget.cpp
+++ b/Userland/Applications/Mail/MailWidget.cpp
@@ -47,7 +47,7 @@ MailWidget::MailWidget()
         if (!Desktop::Launcher::open(url)) {
             GUI::MessageBox::show(
                 window(),
-                DeprecatedString::formatted("The link to '{}' could not be opened.", url),
+                ByteString::formatted("The link to '{}' could not be opened.", url),
                 "Failed to open link"sv,
                 GUI::MessageBox::Type::Error);
         }
@@ -59,7 +59,7 @@ MailWidget::MailWidget()
 
     m_web_view->on_link_hover = [this](auto& url) {
         if (url.is_valid())
-            m_statusbar->set_text(String::from_deprecated_string(url.to_deprecated_string()).release_value_but_fixme_should_propagate_errors());
+            m_statusbar->set_text(String::from_byte_string(url.to_byte_string()).release_value_but_fixme_should_propagate_errors());
         else
             m_statusbar->set_text({});
     };
@@ -72,7 +72,7 @@ MailWidget::MailWidget()
     m_link_context_menu_default_action = link_default_action;
     m_link_context_menu->add_separator();
     m_link_context_menu->add_action(GUI::Action::create("&Copy URL", [this](auto&) {
-        GUI::Clipboard::the().set_plain_text(m_link_context_menu_url.to_deprecated_string());
+        GUI::Clipboard::the().set_plain_text(m_link_context_menu_url.to_byte_string());
     }));
 
     m_web_view->on_link_context_menu_request = [this](auto& url, auto screen_position) {
@@ -86,7 +86,7 @@ MailWidget::MailWidget()
             GUI::Clipboard::the().set_bitmap(*m_image_context_menu_bitmap.bitmap());
     }));
     m_image_context_menu->add_action(GUI::Action::create("Copy Image &URL", [this](auto&) {
-        GUI::Clipboard::the().set_plain_text(m_image_context_menu_url.to_deprecated_string());
+        GUI::Clipboard::the().set_plain_text(m_image_context_menu_url.to_byte_string());
     }));
     m_image_context_menu->add_separator();
     m_image_context_menu->add_action(GUI::Action::create("&Open Image in Browser", [this](auto&) {
@@ -131,7 +131,7 @@ ErrorOr<bool> MailWidget::connect_and_login()
     m_statusbar->set_text(String::formatted("Connecting to {}:{}...", server, port).release_value_but_fixme_should_propagate_errors());
     auto maybe_imap_client = tls ? IMAP::Client::connect_tls(server, port) : IMAP::Client::connect_plaintext(server, port);
     if (maybe_imap_client.is_error()) {
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to connect to '{}:{}' over {}: {}", server, port, tls ? "TLS" : "Plaintext", maybe_imap_client.error()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to connect to '{}:{}' over {}: {}", server, port, tls ? "TLS" : "Plaintext", maybe_imap_client.error()));
         return false;
     }
     m_imap_client = maybe_imap_client.release_value();
@@ -144,7 +144,7 @@ ErrorOr<bool> MailWidget::connect_and_login()
 
     if (response.status() != IMAP::ResponseStatus::OK) {
         dbgln("Failed to login. The server says: '{}'", response.response_text());
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to login. The server says: '{}'", response.response_text()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to login. The server says: '{}'", response.response_text()));
         m_statusbar->set_text("Failed to log in"_string);
         return false;
     }
@@ -154,7 +154,7 @@ ErrorOr<bool> MailWidget::connect_and_login()
 
     if (response.status() != IMAP::ResponseStatus::OK) {
         dbgln("Failed to retrieve mailboxes. The server says: '{}'", response.response_text());
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to retrieve mailboxes. The server says: '{}'", response.response_text()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to retrieve mailboxes. The server says: '{}'", response.response_text()));
         return false;
     }
 
@@ -270,7 +270,7 @@ void MailWidget::selected_mailbox(GUI::ModelIndex const& index)
 
     if (response.status() != IMAP::ResponseStatus::OK) {
         dbgln("Failed to select mailbox. The server says: '{}'", response.response_text());
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to select mailbox. The server says: '{}'", response.response_text()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to select mailbox. The server says: '{}'", response.response_text()));
         return;
     }
 
@@ -301,7 +301,7 @@ void MailWidget::selected_mailbox(GUI::ModelIndex const& index)
     if (fetch_response.status() != IMAP::ResponseStatus::OK) {
         dbgln("Failed to retrieve subject/from for e-mails. The server says: '{}'", response.response_text());
         m_statusbar->set_text(String::formatted("[{}]: Failed to fetch messages :^(", mailbox.name).release_value_but_fixme_should_propagate_errors());
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to retrieve e-mails. The server says: '{}'", response.response_text()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to retrieve e-mails. The server says: '{}'", response.response_text()));
         return;
     }
 
@@ -316,8 +316,8 @@ void MailWidget::selected_mailbox(GUI::ModelIndex const& index)
 
         auto seen = !response_data.flags().find_if([](StringView value) { return value.equals_ignoring_ascii_case("\\Seen"sv); }).is_end();
 
-        DeprecatedString date = internal_date.to_deprecated_string();
-        DeprecatedString subject = envelope.subject.is_empty() ? "(No subject)" : envelope.subject;
+        ByteString date = internal_date.to_byte_string();
+        ByteString subject = envelope.subject.is_empty() ? "(No subject)" : envelope.subject;
         if (subject.contains("=?"sv) && subject.contains("?="sv)) {
             subject = MUST(IMAP::decode_rfc2047_encoded_words(subject)).span();
         }
@@ -347,7 +347,7 @@ void MailWidget::selected_mailbox(GUI::ModelIndex const& index)
                 }
             }
         }
-        DeprecatedString from = sender_builder.to_deprecated_string();
+        ByteString from = sender_builder.to_byte_string();
 
         InboxEntry inbox_entry { sequence_number, date, from, subject, seen };
         m_statusbar->set_text(String::formatted("[{}]: Loading entry {}", mailbox.name, ++i).release_value_but_fixme_should_propagate_errors());
@@ -385,12 +385,12 @@ void MailWidget::selected_email_to_load(GUI::ModelIndex const& index)
 
     if (fetch_response.status() != IMAP::ResponseStatus::OK) {
         dbgln("Failed to retrieve the body structure of the selected e-mail. The server says: '{}'", fetch_response.response_text());
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to retrieve the selected e-mail. The server says: '{}'", fetch_response.response_text()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to retrieve the selected e-mail. The server says: '{}'", fetch_response.response_text()));
         return;
     }
 
     Vector<u32> selected_alternative_position;
-    DeprecatedString selected_alternative_encoding;
+    ByteString selected_alternative_encoding;
 
     auto& response_data = fetch_response.data().fetch_data().last().get<IMAP::FetchResponseData>();
 
@@ -449,7 +449,7 @@ void MailWidget::selected_email_to_load(GUI::ModelIndex const& index)
 
     if (fetch_response.status() != IMAP::ResponseStatus::OK) {
         dbgln("Failed to retrieve the body of the selected e-mail. The server says: '{}'", fetch_response.response_text());
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to retrieve the selected e-mail. The server says: '{}'", fetch_response.response_text()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to retrieve the selected e-mail. The server says: '{}'", fetch_response.response_text()));
         return;
     }
 
@@ -474,7 +474,7 @@ void MailWidget::selected_email_to_load(GUI::ModelIndex const& index)
     }
 
     auto& body_data = fetch_response_data.body_data();
-    auto body_text_part_iterator = body_data.find_if([](Tuple<IMAP::FetchCommand::DataItem, DeprecatedString>& data) {
+    auto body_text_part_iterator = body_data.find_if([](Tuple<IMAP::FetchCommand::DataItem, ByteString>& data) {
         const auto data_item = data.get<0>();
         return data_item.section.has_value() && data_item.section->type == IMAP::FetchCommand::DataItem::SectionType::Parts;
     });
@@ -482,7 +482,7 @@ void MailWidget::selected_email_to_load(GUI::ModelIndex const& index)
 
     auto& encoded_data = body_text_part_iterator->get<1>();
 
-    DeprecatedString decoded_data;
+    ByteString decoded_data;
 
     // FIXME: String uses char internally, so 8bit shouldn't be stored in it.
     //        However, it works for now.
@@ -496,7 +496,7 @@ void MailWidget::selected_email_to_load(GUI::ModelIndex const& index)
         decoded_data = IMAP::decode_quoted_printable(encoded_data).release_value_but_fixme_should_propagate_errors().span();
     } else {
         dbgln("Mail: Unimplemented decoder for encoding: {}", selected_alternative_encoding);
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("The e-mail encoding '{}' is currently unsupported.", selected_alternative_encoding), "Unsupported"sv, GUI::MessageBox::Type::Information);
+        GUI::MessageBox::show(window(), ByteString::formatted("The e-mail encoding '{}' is currently unsupported.", selected_alternative_encoding), "Unsupported"sv, GUI::MessageBox::Type::Information);
         return;
     }
 
diff --git a/Userland/Applications/MailSettings/MailSettingsWidget.cpp b/Userland/Applications/MailSettings/MailSettingsWidget.cpp
index 37bb033cd70..db088591891 100644
--- a/Userland/Applications/MailSettings/MailSettingsWidget.cpp
+++ b/Userland/Applications/MailSettings/MailSettingsWidget.cpp
@@ -60,7 +60,7 @@ ErrorOr<void> MailSettingsWidget::setup()
     m_port_combobox = *find_descendant_of_type_named<GUI::ComboBox>("port_input");
     m_port_combobox->set_text(Config::read_string("Mail"sv, "Connection"sv, "Port"sv, "993"sv));
     m_port_combobox->set_only_allow_values_from_model(false);
-    m_port_combobox->set_model(*GUI::ItemListModel<DeprecatedString>::create(m_common_ports));
+    m_port_combobox->set_model(*GUI::ItemListModel<ByteString>::create(m_common_ports));
     m_port_combobox->on_change = [&](auto, auto) {
         set_modified(true);
     };
diff --git a/Userland/Applications/MailSettings/MailSettingsWidget.h b/Userland/Applications/MailSettings/MailSettingsWidget.h
index 4af6a9496a1..d87768cb9ee 100644
--- a/Userland/Applications/MailSettings/MailSettingsWidget.h
+++ b/Userland/Applications/MailSettings/MailSettingsWidget.h
@@ -24,11 +24,11 @@ private:
     MailSettingsWidget() = default;
     ErrorOr<void> setup();
 
-    DeprecatedString m_server;
-    DeprecatedString m_port;
+    ByteString m_server;
+    ByteString m_port;
     bool m_tls { false };
-    DeprecatedString m_email;
-    Vector<DeprecatedString> m_common_ports;
+    ByteString m_email;
+    Vector<ByteString> m_common_ports;
 
     RefPtr<GUI::TextBox> m_server_inputbox;
     RefPtr<GUI::ComboBox> m_port_combobox;
diff --git a/Userland/Applications/Maps/FavoritesPanel.cpp b/Userland/Applications/Maps/FavoritesPanel.cpp
index c5bde8e74a4..7700ff14ac3 100644
--- a/Userland/Applications/Maps/FavoritesPanel.cpp
+++ b/Userland/Applications/Maps/FavoritesPanel.cpp
@@ -33,7 +33,7 @@ ErrorOr<void> FavoritesPanel::setup()
         if (!index.is_valid())
             return;
         auto& model = *m_favorites_list->model();
-        on_selected_favorite_change({ MUST(String::from_deprecated_string(model.index(index.row(), 0).data().to_deprecated_string())),
+        on_selected_favorite_change({ MUST(String::from_byte_string(model.index(index.row(), 0).data().to_byte_string())),
             { model.index(index.row(), 1).data().as_double(),
                 model.index(index.row(), 2).data().as_double() },
             model.index(index.row(), 3).data().to_i32() });
@@ -63,15 +63,15 @@ void FavoritesPanel::load_favorites()
 {
     Vector<GUI::JsonArrayModel::FieldSpec> favorites_fields;
     favorites_fields.empend("name", "Name"_string, Gfx::TextAlignment::CenterLeft, [](JsonObject const& object) -> GUI::Variant {
-        DeprecatedString name = object.get_deprecated_string("name"sv).release_value();
+        ByteString name = object.get_byte_string("name"sv).release_value();
         double latitude = object.get_double_with_precision_loss("latitude"sv).release_value();
         double longitude = object.get_double_with_precision_loss("longitude"sv).release_value();
-        return DeprecatedString::formatted("{}\n{:.5}, {:.5}", name, latitude, longitude);
+        return ByteString::formatted("{}\n{:.5}, {:.5}", name, latitude, longitude);
     });
     favorites_fields.empend("latitude", "Latitude"_string, Gfx::TextAlignment::CenterLeft);
     favorites_fields.empend("longitude", "Longitude"_string, Gfx::TextAlignment::CenterLeft);
     favorites_fields.empend("zoom", "Zoom"_string, Gfx::TextAlignment::CenterLeft);
-    m_favorites_list->set_model(*GUI::JsonArrayModel::create(DeprecatedString::formatted("{}/MapsFavorites.json", Core::StandardPaths::config_directory()), move(favorites_fields)));
+    m_favorites_list->set_model(*GUI::JsonArrayModel::create(ByteString::formatted("{}/MapsFavorites.json", Core::StandardPaths::config_directory()), move(favorites_fields)));
     m_favorites_list->model()->invalidate();
     favorites_changed();
 }
@@ -80,7 +80,7 @@ ErrorOr<void> FavoritesPanel::add_favorite(Favorite const& favorite)
 {
     auto& model = *static_cast<GUI::JsonArrayModel*>(m_favorites_list->model());
     Vector<JsonValue> favorite_json;
-    favorite_json.append(favorite.name.to_deprecated_string());
+    favorite_json.append(favorite.name.to_byte_string());
     favorite_json.append(favorite.latlng.latitude);
     favorite_json.append(favorite.latlng.longitude);
     favorite_json.append(favorite.zoom);
@@ -109,7 +109,7 @@ ErrorOr<void> FavoritesPanel::edit_favorite(int row)
     edit_dialog->set_main_widget(widget);
 
     auto& name_textbox = *widget->find_descendant_of_type_named<GUI::TextBox>("name_textbox");
-    name_textbox.set_text(model.index(row, 0).data().to_deprecated_string().split('\n').at(0));
+    name_textbox.set_text(model.index(row, 0).data().to_byte_string().split('\n').at(0));
     name_textbox.set_focus(true);
     name_textbox.select_all();
 
@@ -144,7 +144,7 @@ void FavoritesPanel::favorites_changed()
 
     Vector<Favorite> favorites;
     for (int index = 0; index < model.row_count(); index++)
-        favorites.append({ MUST(String::from_deprecated_string(model.index(index, 0).data().to_deprecated_string())),
+        favorites.append({ MUST(String::from_byte_string(model.index(index, 0).data().to_byte_string())),
             { model.index(index, 1).data().as_double(),
                 model.index(index, 2).data().as_double() },
             model.index(index, 3).data().to_i32() });
diff --git a/Userland/Applications/Maps/MapWidget.cpp b/Userland/Applications/Maps/MapWidget.cpp
index 2d642abc34e..70b8105db7c 100644
--- a/Userland/Applications/Maps/MapWidget.cpp
+++ b/Userland/Applications/Maps/MapWidget.cpp
@@ -73,12 +73,12 @@ MapWidget::MapWidget(Options const& options)
 {
     m_request_client = Protocol::RequestClient::try_create().release_value_but_fixme_should_propagate_errors();
     if (options.attribution_enabled) {
-        auto attribution_text = options.attribution_text.value_or(MUST(String::from_deprecated_string(Config::read_string("Maps"sv, "MapWidget"sv, "TileProviderAttributionText"sv, Maps::default_tile_provider_attribution_text))));
+        auto attribution_text = options.attribution_text.value_or(MUST(String::from_byte_string(Config::read_string("Maps"sv, "MapWidget"sv, "TileProviderAttributionText"sv, Maps::default_tile_provider_attribution_text))));
         URL attribution_url = options.attribution_url.value_or(URL(Config::read_string("Maps"sv, "MapWidget"sv, "TileProviderAttributionUrl"sv, Maps::default_tile_provider_attribution_url)));
         add_panel({ attribution_text, Panel::Position::BottomRight, attribution_url, "attribution"_string });
     }
     m_marker_image = Gfx::Bitmap::load_from_file("/res/graphics/maps/marker-blue.png"sv).release_value_but_fixme_should_propagate_errors();
-    m_default_tile_provider = MUST(String::from_deprecated_string(Config::read_string("Maps"sv, "MapWidget"sv, "TileProviderUrlFormat"sv, Maps::default_tile_provider_url_format)));
+    m_default_tile_provider = MUST(String::from_byte_string(Config::read_string("Maps"sv, "MapWidget"sv, "TileProviderUrlFormat"sv, Maps::default_tile_provider_url_format)));
 }
 
 void MapWidget::set_zoom(int zoom)
@@ -315,7 +315,7 @@ void MapWidget::process_tile_queue()
     auto tile_key = m_tile_queue.dequeue();
 
     // Start HTTP GET request to load image
-    HashMap<DeprecatedString, DeprecatedString> headers;
+    HashMap<ByteString, ByteString> headers;
     headers.set("User-Agent", "SerenityOS Maps");
     headers.set("Accept", "image/png");
     URL url(MUST(String::formatted(m_tile_provider.value_or(m_default_tile_provider), tile_key.zoom, tile_key.x, tile_key.y)));
diff --git a/Userland/Applications/Maps/SearchPanel.cpp b/Userland/Applications/Maps/SearchPanel.cpp
index 881ebbe7992..79119eaef82 100644
--- a/Userland/Applications/Maps/SearchPanel.cpp
+++ b/Userland/Applications/Maps/SearchPanel.cpp
@@ -30,10 +30,10 @@ ErrorOr<void> SearchPanel::setup()
     m_places_list->set_visible(false);
 
     m_search_textbox->on_return_pressed = [this]() {
-        search(MUST(String::from_deprecated_string(m_search_textbox->text())));
+        search(MUST(String::from_byte_string(m_search_textbox->text())));
     };
     m_search_button->on_click = [this](unsigned) {
-        search(MUST(String::from_deprecated_string(m_search_textbox->text())));
+        search(MUST(String::from_byte_string(m_search_textbox->text())));
     };
 
     m_places_list->set_item_height(m_places_list->font().preferred_line_height() * 2 + m_places_list->vertical_padding());
@@ -59,7 +59,7 @@ void SearchPanel::search(StringView query)
     m_start_container->set_visible(false);
 
     // Start HTTP GET request to load people.json
-    HashMap<DeprecatedString, DeprecatedString> headers;
+    HashMap<ByteString, ByteString> headers;
     headers.set("User-Agent", "SerenityOS Maps");
     headers.set("Accept", "application/json");
     URL url(MUST(String::formatted("https://nominatim.openstreetmap.org/search?q={}&format=json", AK::URL::percent_encode(query, AK::URL::PercentEncodeSet::Query))));
@@ -96,9 +96,9 @@ void SearchPanel::search(StringView query)
             // FIXME: Handle JSON parsing errors
             auto const& json_place = json_places.at(i).as_object();
 
-            MapWidget::LatLng latlng = { json_place.get_deprecated_string("lat"sv).release_value().to_double().release_value(),
-                json_place.get_deprecated_string("lon"sv).release_value().to_double().release_value() };
-            String name = MUST(String::formatted("{}\n{:.5}, {:.5}", json_place.get_deprecated_string("display_name"sv).release_value(), latlng.latitude, latlng.longitude));
+            MapWidget::LatLng latlng = { json_place.get_byte_string("lat"sv).release_value().to_double().release_value(),
+                json_place.get_byte_string("lon"sv).release_value().to_double().release_value() };
+            String name = MUST(String::formatted("{}\n{:.5}, {:.5}", json_place.get_byte_string("display_name"sv).release_value(), latlng.latitude, latlng.longitude));
 
             // Calculate the right zoom level for bounding box
             auto const& json_boundingbox = json_place.get_array("boundingbox"sv);
diff --git a/Userland/Applications/Maps/UsersMapWidget.cpp b/Userland/Applications/Maps/UsersMapWidget.cpp
index dadb2469146..6fcbe62bf92 100644
--- a/Userland/Applications/Maps/UsersMapWidget.cpp
+++ b/Userland/Applications/Maps/UsersMapWidget.cpp
@@ -19,7 +19,7 @@ UsersMapWidget::UsersMapWidget(Options const& options)
 void UsersMapWidget::get_users()
 {
     // Start HTTP GET request to load people.json
-    HashMap<DeprecatedString, DeprecatedString> headers;
+    HashMap<ByteString, ByteString> headers;
     headers.set("User-Agent", "SerenityOS Maps");
     headers.set("Accept", "application/json");
     URL url("https://usermap.serenityos.org/people.json");
@@ -48,7 +48,7 @@ void UsersMapWidget::get_users()
         for (size_t i = 0; i < json_users.size(); i++) {
             auto const& json_user = json_users.at(i).as_object();
             User user {
-                MUST(String::from_deprecated_string(json_user.get_deprecated_string("nick"sv).release_value())),
+                MUST(String::from_byte_string(json_user.get_byte_string("nick"sv).release_value())),
                 { json_user.get_array("coordinates"sv).release_value().at(0).to_double(),
                     json_user.get_array("coordinates"sv).release_value().at(1).to_double() },
                 json_user.has_bool("contributor"sv),
diff --git a/Userland/Applications/Maps/main.cpp b/Userland/Applications/Maps/main.cpp
index 941858adb2d..296821beaba 100644
--- a/Userland/Applications/Maps/main.cpp
+++ b/Userland/Applications/Maps/main.cpp
@@ -68,7 +68,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     map_widget.set_show_users(Config::read_bool("Maps"sv, "MapView"sv, "ShowUsers"sv, false));
 
     // Panels
-    String init_panel_open_name = TRY(String::from_deprecated_string(Config::read_string("Maps"sv, "Panel"sv, "OpenName"sv, ""sv)));
+    String init_panel_open_name = TRY(String::from_byte_string(Config::read_string("Maps"sv, "Panel"sv, "OpenName"sv, ""sv)));
     int panel_width = Config::read_i32("Maps"sv, "Panel"sv, "Width"sv, INT_MIN);
 
     // Search panel
diff --git a/Userland/Applications/MapsSettings/MapsSettingsWidget.cpp b/Userland/Applications/MapsSettings/MapsSettingsWidget.cpp
index ec50f49640f..9d94d26a0b8 100644
--- a/Userland/Applications/MapsSettings/MapsSettingsWidget.cpp
+++ b/Userland/Applications/MapsSettings/MapsSettingsWidget.cpp
@@ -29,11 +29,11 @@ void MapsSettingsWidget::apply_settings()
         Config::remove_key("Maps"sv, "MapWidget"sv, "TileProviderAttributionText"sv);
         Config::remove_key("Maps"sv, "MapWidget"sv, "TileProviderAttributionUrl"sv);
     } else {
-        auto tile_provider_url_format = m_tile_provider_combobox->model()->index(m_tile_provider_combobox->selected_index(), 1).data().to_deprecated_string();
+        auto tile_provider_url_format = m_tile_provider_combobox->model()->index(m_tile_provider_combobox->selected_index(), 1).data().to_byte_string();
         Config::write_string("Maps"sv, "MapWidget"sv, "TileProviderUrlFormat"sv, tile_provider_url_format);
-        auto tile_provider_attribution_text = m_tile_provider_combobox->model()->index(m_tile_provider_combobox->selected_index(), 2).data().to_deprecated_string();
+        auto tile_provider_attribution_text = m_tile_provider_combobox->model()->index(m_tile_provider_combobox->selected_index(), 2).data().to_byte_string();
         Config::write_string("Maps"sv, "MapWidget"sv, "TileProviderAttributionText"sv, tile_provider_attribution_text);
-        auto tile_provider_attribution_url = m_tile_provider_combobox->model()->index(m_tile_provider_combobox->selected_index(), 3).data().to_deprecated_string();
+        auto tile_provider_attribution_url = m_tile_provider_combobox->model()->index(m_tile_provider_combobox->selected_index(), 3).data().to_byte_string();
         Config::write_string("Maps"sv, "MapWidget"sv, "TileProviderAttributionUrl"sv, tile_provider_attribution_url);
     }
 }
@@ -51,7 +51,7 @@ ErrorOr<void> MapsSettingsWidget::setup()
     tile_provider_fields.empend("url_format", "URL format"_string, Gfx::TextAlignment::CenterLeft);
     tile_provider_fields.empend("attribution_text", "Attribution text"_string, Gfx::TextAlignment::CenterLeft);
     tile_provider_fields.empend("attribution_url", "Attribution URL"_string, Gfx::TextAlignment::CenterLeft);
-    auto tile_providers = GUI::JsonArrayModel::create(DeprecatedString::formatted("{}/MapsTileProviders.json", Core::StandardPaths::config_directory()), move(tile_provider_fields));
+    auto tile_providers = GUI::JsonArrayModel::create(ByteString::formatted("{}/MapsTileProviders.json", Core::StandardPaths::config_directory()), move(tile_provider_fields));
     tile_providers->invalidate();
 
     Vector<JsonValue> custom_tile_provider;
@@ -71,8 +71,8 @@ ErrorOr<void> MapsSettingsWidget::setup()
     m_custom_tile_provider_textbox->set_placeholder(Maps::default_tile_provider_url_format);
     m_custom_tile_provider_textbox->on_change = [&]() { set_modified(true); };
 
-    m_tile_provider_combobox->on_change = [&](DeprecatedString const&, GUI::ModelIndex const& index) {
-        auto tile_provider_url_format = m_tile_provider_combobox->model()->index(index.row(), 1).data().to_deprecated_string();
+    m_tile_provider_combobox->on_change = [&](ByteString const&, GUI::ModelIndex const& index) {
+        auto tile_provider_url_format = m_tile_provider_combobox->model()->index(index.row(), 1).data().to_byte_string();
         m_is_custom_tile_provider = tile_provider_url_format.is_empty();
         m_custom_tile_provider_group->set_enabled(m_is_custom_tile_provider);
         set_modified(true);
@@ -86,7 +86,7 @@ void MapsSettingsWidget::set_tile_provider(StringView tile_provider_url_format)
 {
     bool found = false;
     for (int index = 0; index < m_tile_provider_combobox->model()->row_count(); index++) {
-        auto url_format = m_tile_provider_combobox->model()->index(index, 1).data().to_deprecated_string();
+        auto url_format = m_tile_provider_combobox->model()->index(index, 1).data().to_byte_string();
         if (url_format == tile_provider_url_format) {
             m_tile_provider_combobox->set_selected_index(index, GUI::AllowCallback::No);
             found = true;
diff --git a/Userland/Applications/MouseSettings/HighlightPreviewWidget.cpp b/Userland/Applications/MouseSettings/HighlightPreviewWidget.cpp
index f51142d333d..f46018b2c36 100644
--- a/Userland/Applications/MouseSettings/HighlightPreviewWidget.cpp
+++ b/Userland/Applications/MouseSettings/HighlightPreviewWidget.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "HighlightPreviewWidget.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/ConfigFile.h>
 #include <LibGUI/ConnectionToWindowServer.h>
 #include <LibGUI/Painter.h>
@@ -22,7 +22,7 @@ HighlightPreviewWidget::HighlightPreviewWidget(Gfx::Palette const& palette)
 ErrorOr<void> HighlightPreviewWidget::reload_cursor()
 {
     auto cursor_theme = GUI::ConnectionToWindowServer::the().get_cursor_theme();
-    auto theme_path = DeprecatedString::formatted("/res/cursor-themes/{}/{}", cursor_theme, "Config.ini");
+    auto theme_path = ByteString::formatted("/res/cursor-themes/{}/{}", cursor_theme, "Config.ini");
     auto cursor_theme_config = TRY(Core::ConfigFile::open(theme_path));
     auto load_bitmap = [](StringView path, StringView default_path) {
         auto maybe_bitmap = Gfx::Bitmap::load_from_file(path);
@@ -31,7 +31,7 @@ ErrorOr<void> HighlightPreviewWidget::reload_cursor()
         return Gfx::Bitmap::load_from_file(default_path);
     };
     constexpr auto default_cursor_path = "/res/cursor-themes/Default/arrow.x2y2.png"sv;
-    auto cursor_path = DeprecatedString::formatted("/res/cursor-themes/{}/{}",
+    auto cursor_path = ByteString::formatted("/res/cursor-themes/{}/{}",
         cursor_theme, cursor_theme_config->read_entry("Cursor", "Arrow"));
     m_cursor_bitmap = TRY(load_bitmap(cursor_path, default_cursor_path));
     m_cursor_params = Gfx::CursorParams::parse_from_filename(cursor_path, m_cursor_bitmap->rect().center()).constrained(*m_cursor_bitmap);
diff --git a/Userland/Applications/MouseSettings/ThemeWidget.cpp b/Userland/Applications/MouseSettings/ThemeWidget.cpp
index c595f23fc58..137247c245a 100644
--- a/Userland/Applications/MouseSettings/ThemeWidget.cpp
+++ b/Userland/Applications/MouseSettings/ThemeWidget.cpp
@@ -51,7 +51,7 @@ void MouseCursorModel::invalidate()
 
     m_cursors.clear();
     // FIXME: Propagate errors.
-    (void)Core::Directory::for_each_entry(DeprecatedString::formatted("/res/cursor-themes/{}", m_theme_name), Core::DirIterator::Flags::SkipDots, [&](auto const& entry, auto const& directory) -> ErrorOr<IterationDecision> {
+    (void)Core::Directory::for_each_entry(ByteString::formatted("/res/cursor-themes/{}", m_theme_name), Core::DirIterator::Flags::SkipDots, [&](auto const& entry, auto const& directory) -> ErrorOr<IterationDecision> {
         auto path = LexicalPath::join(directory.path().string(), entry.name);
         if (path.has_extension(".ini"sv))
             return IterationDecision::Continue;
@@ -89,7 +89,7 @@ void ThemeModel::invalidate()
 
     // FIXME: Propagate errors.
     (void)Core::Directory::for_each_entry("/res/cursor-themes"sv, Core::DirIterator::Flags::SkipDots, [&](auto const& entry, auto&) -> ErrorOr<IterationDecision> {
-        if (access(DeprecatedString::formatted("/res/cursor-themes/{}/Config.ini", entry.name).characters(), R_OK) == 0)
+        if (access(ByteString::formatted("/res/cursor-themes/{}/Config.ini", entry.name).characters(), R_OK) == 0)
             m_themes.append(entry.name);
         return IterationDecision::Continue;
     });
@@ -127,7 +127,7 @@ ErrorOr<void> ThemeWidget::setup()
     m_mouse_cursor_model->change_theme(theme_name);
 
     m_theme_name_box = find_descendant_of_type_named<GUI::ComboBox>("theme_name_box");
-    m_theme_name_box->on_change = [this](DeprecatedString const& value, GUI::ModelIndex const&) {
+    m_theme_name_box->on_change = [this](ByteString const& value, GUI::ModelIndex const&) {
         m_mouse_cursor_model->change_theme(value);
         set_modified(true);
     };
diff --git a/Userland/Applications/MouseSettings/ThemeWidget.h b/Userland/Applications/MouseSettings/ThemeWidget.h
index 2308745c7b0..5c17717f88c 100644
--- a/Userland/Applications/MouseSettings/ThemeWidget.h
+++ b/Userland/Applications/MouseSettings/ThemeWidget.h
@@ -29,7 +29,7 @@ public:
     virtual GUI::Variant data(const GUI::ModelIndex& index, GUI::ModelRole role) const override;
     virtual void invalidate() override;
 
-    void change_theme(DeprecatedString const& name)
+    void change_theme(ByteString const& name)
     {
         m_theme_name = name;
         invalidate();
@@ -40,13 +40,13 @@ private:
 
     struct Cursor {
         RefPtr<Gfx::Bitmap> bitmap;
-        DeprecatedString path;
-        DeprecatedString name;
+        ByteString path;
+        ByteString name;
         Gfx::CursorParams params;
     };
 
     Vector<Cursor> m_cursors;
-    DeprecatedString m_theme_name;
+    ByteString m_theme_name;
 };
 
 class ThemeModel final : public GUI::Model {
@@ -59,7 +59,7 @@ public:
     virtual void invalidate() override;
 
 private:
-    Vector<DeprecatedString> m_themes;
+    Vector<ByteString> m_themes;
 };
 
 class ThemeWidget final : public GUI::SettingsWindow::Tab {
diff --git a/Userland/Applications/NetworkSettings/NetworkSettingsWidget.cpp b/Userland/Applications/NetworkSettings/NetworkSettingsWidget.cpp
index e67b1a54702..b6d284f4e4e 100644
--- a/Userland/Applications/NetworkSettings/NetworkSettingsWidget.cpp
+++ b/Userland/Applications/NetworkSettings/NetworkSettingsWidget.cpp
@@ -6,7 +6,7 @@
  */
 
 #include "NetworkSettingsWidget.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/IPv4Address.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonParser.h>
@@ -78,7 +78,7 @@ ErrorOr<void> NetworkSettingsWidget::setup()
     size_t index = 0;
     proc_net_adapters_json.as_array().for_each([&](auto& value) {
         auto& if_object = value.as_object();
-        auto adapter_name = if_object.get_deprecated_string("name"sv).value();
+        auto adapter_name = if_object.get_byte_string("name"sv).value();
         if (adapter_name == "loop")
             return;
 
@@ -106,8 +106,8 @@ ErrorOr<void> NetworkSettingsWidget::setup()
         ::exit(1);
     }
 
-    m_adapters_combobox->set_model(GUI::ItemListModel<DeprecatedString>::create(m_adapter_names));
-    m_adapters_combobox->on_change = [this](DeprecatedString const& text, GUI::ModelIndex const&) {
+    m_adapters_combobox->set_model(GUI::ItemListModel<ByteString>::create(m_adapter_names));
+    m_adapters_combobox->on_change = [this](ByteString const& text, GUI::ModelIndex const&) {
         on_switch_adapter(text);
     };
     auto const& selected_adapter = selected_adapter_index;
@@ -117,7 +117,7 @@ ErrorOr<void> NetworkSettingsWidget::setup()
     return {};
 }
 
-void NetworkSettingsWidget::on_switch_adapter(DeprecatedString const& adapter)
+void NetworkSettingsWidget::on_switch_adapter(ByteString const& adapter)
 {
     auto& adapter_data = m_network_adapters.get(adapter).value();
     m_current_adapter_data = &adapter_data;
@@ -198,7 +198,7 @@ ErrorOr<Optional<JsonObject>> NetworkSettingsWidget::create_settings_object()
         adapter.set("Enabled", adapter_data.value.enabled);
         adapter.set("DHCP", adapter_data.value.dhcp);
         adapter.set("IPv4Address", adapter_data.value.ip_address);
-        adapter.set("IPv4Netmask", netmask.to_deprecated_string());
+        adapter.set("IPv4Netmask", netmask.to_byte_string());
         adapter.set("IPv4Gateway", adapter_data.value.default_gateway);
         json.set(adapter_data.key, move(adapter));
     }
@@ -206,7 +206,7 @@ ErrorOr<Optional<JsonObject>> NetworkSettingsWidget::create_settings_object()
     return json;
 }
 
-void NetworkSettingsWidget::switch_adapter(DeprecatedString const& adapter)
+void NetworkSettingsWidget::switch_adapter(ByteString const& adapter)
 {
     m_adapters_combobox->set_text(adapter, GUI::AllowCallback::No);
     on_switch_adapter(adapter);
diff --git a/Userland/Applications/NetworkSettings/NetworkSettingsWidget.h b/Userland/Applications/NetworkSettings/NetworkSettingsWidget.h
index 8123741dcbf..7b739e30db7 100644
--- a/Userland/Applications/NetworkSettings/NetworkSettingsWidget.h
+++ b/Userland/Applications/NetworkSettings/NetworkSettingsWidget.h
@@ -19,7 +19,7 @@ public:
     static ErrorOr<NonnullRefPtr<NetworkSettingsWidget>> create();
 
     virtual void apply_settings() override;
-    void switch_adapter(DeprecatedString const& adapter);
+    void switch_adapter(ByteString const& adapter);
 
 protected:
     static ErrorOr<NonnullRefPtr<NetworkSettingsWidget>> try_create();
@@ -31,18 +31,18 @@ private:
     struct NetworkAdapterData {
         bool enabled = false;
         bool dhcp = false;
-        DeprecatedString ip_address;
+        ByteString ip_address;
         int cidr = 0;
-        DeprecatedString default_gateway;
+        ByteString default_gateway;
     };
 
-    void on_switch_adapter(DeprecatedString const& adapter);
+    void on_switch_adapter(ByteString const& adapter);
     void on_switch_enabled_or_dhcp();
     ErrorOr<void> apply_settings_impl();
     ErrorOr<Optional<JsonObject>> create_settings_object();
 
-    HashMap<DeprecatedString, NetworkAdapterData> m_network_adapters;
-    Vector<DeprecatedString> m_adapter_names;
+    HashMap<ByteString, NetworkAdapterData> m_network_adapters;
+    Vector<ByteString> m_adapter_names;
     NetworkAdapterData* m_current_adapter_data = nullptr;
 
     RefPtr<GUI::CheckBox> m_enabled_checkbox;
diff --git a/Userland/Applications/PDFViewer/NumericInput.cpp b/Userland/Applications/PDFViewer/NumericInput.cpp
index d3ee9e01c57..34df9e2c4e1 100644
--- a/Userland/Applications/PDFViewer/NumericInput.cpp
+++ b/Userland/Applications/PDFViewer/NumericInput.cpp
@@ -26,7 +26,7 @@ NumericInput::NumericInput()
             first = false;
         }
 
-        auto new_number_opt = builder.to_deprecated_string().to_int();
+        auto new_number_opt = builder.to_byte_string().to_int();
         if (!new_number_opt.has_value()) {
             m_needs_text_reset = true;
             return;
@@ -34,7 +34,7 @@ NumericInput::NumericInput()
             m_needs_text_reset = false;
         }
 
-        set_text(builder.to_deprecated_string());
+        set_text(builder.to_byte_string());
         set_current_number(new_number_opt.value(), GUI::AllowCallback::No);
     };
 
@@ -70,7 +70,7 @@ void NumericInput::set_max_number(i32 number)
 void NumericInput::on_focus_lost()
 {
     if (m_needs_text_reset) {
-        set_text(DeprecatedString::number(m_current_number));
+        set_text(ByteString::number(m_current_number));
         m_needs_text_reset = false;
     }
     if (on_number_changed)
@@ -83,7 +83,7 @@ void NumericInput::set_current_number(i32 number, GUI::AllowCallback allow_callb
         return;
 
     m_current_number = clamp(number, m_min_number, m_max_number);
-    set_text(DeprecatedString::number(m_current_number));
+    set_text(ByteString::number(m_current_number));
     if (on_number_changed && allow_callback == GUI::AllowCallback::Yes)
         on_number_changed(m_current_number);
 }
diff --git a/Userland/Applications/PDFViewer/PDFViewerWidget.cpp b/Userland/Applications/PDFViewer/PDFViewerWidget.cpp
index acaeb7b8f89..3c53d0e27d3 100644
--- a/Userland/Applications/PDFViewer/PDFViewerWidget.cpp
+++ b/Userland/Applications/PDFViewer/PDFViewerWidget.cpp
@@ -7,7 +7,7 @@
 
 #include "PDFViewerWidget.h"
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/HashMap.h>
 #include <AK/HashTable.h>
@@ -38,7 +38,7 @@ class PagedErrorsModel : public GUI::Model {
         _Count
     };
 
-    using PageErrors = AK::OrderedHashTable<DeprecatedString>;
+    using PageErrors = AK::OrderedHashTable<ByteString>;
     using PagedErrors = HashMap<u32, PageErrors>;
 
 public:
@@ -102,7 +102,7 @@ public:
             case Columns::Page:
                 return m_pages_with_errors[index.row()] + 1;
             case Columns::Message:
-                return DeprecatedString::formatted("{} errors", error_count_in_page(index));
+                return ByteString::formatted("{} errors", error_count_in_page(index));
             default:
                 VERIFY_NOT_REACHED();
             }
@@ -366,14 +366,14 @@ void PDFViewerWidget::open_file(StringView path, NonnullOwnPtr<Core::File> file)
     if (maybe_error.is_error()) {
         auto error = maybe_error.release_error();
         warnln("{}", error.message());
-        auto user_error_message = DeprecatedString::formatted("Failed to load the document. Error:\n{}.", error.message());
+        auto user_error_message = ByteString::formatted("Failed to load the document. Error:\n{}.", error.message());
         GUI::MessageBox::show_error(nullptr, user_error_message.view());
     }
 }
 
 PDF::PDFErrorOr<void> PDFViewerWidget::try_open_file(StringView path, NonnullOwnPtr<Core::File> file)
 {
-    window()->set_title(DeprecatedString::formatted("{} - PDF Viewer", path));
+    window()->set_title(ByteString::formatted("{} - PDF Viewer", path));
 
     m_buffer = TRY(file->read_until_eof());
     auto document = TRY(PDF::Document::create(m_buffer));
diff --git a/Userland/Applications/PartitionEditor/PartitionModel.cpp b/Userland/Applications/PartitionEditor/PartitionModel.cpp
index 6f8b53ae7a1..bbd0082081a 100644
--- a/Userland/Applications/PartitionEditor/PartitionModel.cpp
+++ b/Userland/Applications/PartitionEditor/PartitionModel.cpp
@@ -65,7 +65,7 @@ GUI::Variant PartitionModel::data(GUI::ModelIndex const& index, GUI::ModelRole r
     return {};
 }
 
-ErrorOr<void> PartitionModel::set_device_path(DeprecatedString const& path)
+ErrorOr<void> PartitionModel::set_device_path(ByteString const& path)
 {
     auto strong_file = TRY(Core::File::open(path, Core::File::OpenMode::Read));
     auto weak_file = TRY(Core::File::adopt_fd(strong_file->fd(), Core::File::OpenMode::Read, Core::File::ShouldCloseFileDescriptor::No));
diff --git a/Userland/Applications/PartitionEditor/PartitionModel.h b/Userland/Applications/PartitionEditor/PartitionModel.h
index bc3a1febe42..858f2a5fa98 100644
--- a/Userland/Applications/PartitionEditor/PartitionModel.h
+++ b/Userland/Applications/PartitionEditor/PartitionModel.h
@@ -31,7 +31,7 @@ public:
     virtual ErrorOr<String> column_name(int) const override;
     virtual GUI::Variant data(GUI::ModelIndex const&, GUI::ModelRole) const override;
 
-    ErrorOr<void> set_device_path(DeprecatedString const&);
+    ErrorOr<void> set_device_path(ByteString const&);
 
 private:
     PartitionModel() = default;
diff --git a/Userland/Applications/PartitionEditor/main.cpp b/Userland/Applications/PartitionEditor/main.cpp
index 16fa493d85c..80f6cb9a929 100644
--- a/Userland/Applications/PartitionEditor/main.cpp
+++ b/Userland/Applications/PartitionEditor/main.cpp
@@ -17,9 +17,9 @@
 #include <LibGUI/TableView.h>
 #include <unistd.h>
 
-static Vector<DeprecatedString> get_device_paths()
+static Vector<ByteString> get_device_paths()
 {
-    auto device_paths = Vector<DeprecatedString>();
+    auto device_paths = Vector<ByteString>();
     // FIXME: Propagate errors.
     (void)Core::Directory::for_each_entry("/dev"sv, Core::DirIterator::Flags::SkipParentAndBaseDir, [&](auto const& entry, auto const& directory) -> ErrorOr<IterationDecision> {
         auto full_path = LexicalPath::join(directory.path().string(), entry.name).string();
@@ -67,13 +67,13 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(partition_model->set_device_path(device_paths.first()));
 
     auto& device_combobox = *widget->find_descendant_of_type_named<GUI::ComboBox>("device_combobox");
-    device_combobox.set_model(GUI::ItemListModel<DeprecatedString>::create(device_paths));
+    device_combobox.set_model(GUI::ItemListModel<ByteString>::create(device_paths));
     device_combobox.set_only_allow_values_from_model(true);
     device_combobox.set_selected_index(0);
     device_combobox.on_change = [&](auto const& path, auto const&) {
         auto result = partition_model->set_device_path(path);
         if (result.is_error())
-            GUI::MessageBox::show_error(window, DeprecatedString::formatted("No partition table found for device {}", path));
+            GUI::MessageBox::show_error(window, ByteString::formatted("No partition table found for device {}", path));
     };
 
     auto& partition_table_view = *widget->find_descendant_of_type_named<GUI::TableView>("partition_table_view");
diff --git a/Userland/Applications/Piano/ExportProgressWindow.cpp b/Userland/Applications/Piano/ExportProgressWindow.cpp
index 9664af7fcbe..8b40e28660b 100644
--- a/Userland/Applications/Piano/ExportProgressWindow.cpp
+++ b/Userland/Applications/Piano/ExportProgressWindow.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "ExportProgressWindow.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <Applications/Piano/ExportProgressWidget.h>
 #include <LibGUI/Icon.h>
 #include <LibGUI/Label.h>
diff --git a/Userland/Applications/Piano/PlayerWidget.cpp b/Userland/Applications/Piano/PlayerWidget.cpp
index 1eff90f3b84..f7b5a66fea5 100644
--- a/Userland/Applications/Piano/PlayerWidget.cpp
+++ b/Userland/Applications/Piano/PlayerWidget.cpp
@@ -50,7 +50,7 @@ ErrorOr<void> PlayerWidget::initialize()
 
     m_track_dropdown = add<GUI::ComboBox>();
     m_track_dropdown->set_max_width(75);
-    m_track_dropdown->set_model(*GUI::ItemListModel<DeprecatedString>::create(m_track_number_choices));
+    m_track_dropdown->set_model(*GUI::ItemListModel<ByteString>::create(m_track_number_choices));
     m_track_dropdown->set_only_allow_values_from_model(true);
     m_track_dropdown->set_model_column(0);
     m_track_dropdown->set_selected_index(0);
@@ -117,7 +117,7 @@ void PlayerWidget::add_track()
 {
     m_track_manager.add_track();
     auto latest_track_count = m_track_manager.track_count();
-    auto latest_track_string = DeprecatedString::number(latest_track_count);
+    auto latest_track_string = ByteString::number(latest_track_count);
     m_track_number_choices.append(latest_track_string);
     m_track_dropdown->set_selected_index(latest_track_count - 1);
 }
diff --git a/Userland/Applications/Piano/PlayerWidget.h b/Userland/Applications/Piano/PlayerWidget.h
index 072484b4954..da2088c0dc2 100644
--- a/Userland/Applications/Piano/PlayerWidget.h
+++ b/Userland/Applications/Piano/PlayerWidget.h
@@ -31,7 +31,7 @@ private:
     TrackManager& m_track_manager;
     MainWidget& m_main_widget;
     AudioPlayerLoop& m_audio_loop;
-    Vector<DeprecatedString> m_track_number_choices;
+    Vector<ByteString> m_track_number_choices;
 
     RefPtr<Gfx::Bitmap> m_play_icon;
     RefPtr<Gfx::Bitmap> m_pause_icon;
diff --git a/Userland/Applications/Piano/ProcessorParameterWidget/Dropdown.h b/Userland/Applications/Piano/ProcessorParameterWidget/Dropdown.h
index 0e4c25f6755..52aff71f483 100644
--- a/Userland/Applications/Piano/ProcessorParameterWidget/Dropdown.h
+++ b/Userland/Applications/Piano/ProcessorParameterWidget/Dropdown.h
@@ -20,12 +20,12 @@ class ProcessorParameterDropdown : public GUI::ComboBox {
     C_OBJECT(ProcessorParameterDropdown);
 
 public:
-    ProcessorParameterDropdown(DSP::ProcessorEnumParameter<EnumT>& parameter, Vector<DeprecatedString> modes)
+    ProcessorParameterDropdown(DSP::ProcessorEnumParameter<EnumT>& parameter, Vector<ByteString> modes)
         : ComboBox()
         , m_parameter(parameter)
         , m_modes(move(modes))
     {
-        auto model = GUI::ItemListModel<EnumT, Vector<DeprecatedString>>::create(m_modes);
+        auto model = GUI::ItemListModel<EnumT, Vector<ByteString>>::create(m_modes);
         set_model(model);
         set_only_allow_values_from_model(true);
         set_model_column(0);
@@ -55,5 +55,5 @@ public:
 
 private:
     DSP::ProcessorEnumParameter<EnumT>& m_parameter;
-    Vector<DeprecatedString> m_modes;
+    Vector<ByteString> m_modes;
 };
diff --git a/Userland/Applications/Piano/ProcessorParameterWidget/ParameterWidget.cpp b/Userland/Applications/Piano/ProcessorParameterWidget/ParameterWidget.cpp
index 16d7377b499..cd520316fbe 100644
--- a/Userland/Applications/Piano/ProcessorParameterWidget/ParameterWidget.cpp
+++ b/Userland/Applications/Piano/ProcessorParameterWidget/ParameterWidget.cpp
@@ -26,7 +26,7 @@ ProcessorParameterWidget::ProcessorParameterWidget(DSP::ProcessorParameter& raw_
     case DSP::ParameterType::Enum: {
         // FIXME: We shouldn't do that, but the only user is the synth right now.
         auto& parameter = static_cast<DSP::ProcessorEnumParameter<DSP::Synthesizers::Waveform>&>(raw_parameter);
-        auto enum_strings = Vector<DeprecatedString> { "Sine", "Triangle", "Square", "Saw", "Noise" };
+        auto enum_strings = Vector<ByteString> { "Sine", "Triangle", "Square", "Saw", "Noise" };
         m_parameter_modifier = add<ProcessorParameterDropdown<DSP::Synthesizers::Waveform>>(parameter, move(enum_strings));
         break;
     }
diff --git a/Userland/Applications/Piano/RollWidget.cpp b/Userland/Applications/Piano/RollWidget.cpp
index 2da845aac2b..5ba2defb17b 100644
--- a/Userland/Applications/Piano/RollWidget.cpp
+++ b/Userland/Applications/Piano/RollWidget.cpp
@@ -163,7 +163,7 @@ void RollWidget::paint_event(GUI::PaintEvent& event)
         painter.draw_text(note_name_rect, note_name, Gfx::TextAlignment::CenterLeft);
         note_name_rect.translate_by(Gfx::FontDatabase::default_font().width(note_name) + 2, 0);
         if (note % notes_per_octave == 0)
-            painter.draw_text(note_name_rect, DeprecatedString::formatted("{}", note / notes_per_octave + 1), Gfx::TextAlignment::CenterLeft);
+            painter.draw_text(note_name_rect, ByteString::formatted("{}", note / notes_per_octave + 1), Gfx::TextAlignment::CenterLeft);
     }
 
     int x = m_roll_width * (static_cast<double>(m_track_manager.transport()->time()) / roll_length);
diff --git a/Userland/Applications/Piano/SamplerWidget.cpp b/Userland/Applications/Piano/SamplerWidget.cpp
index 235402f3fe2..94f78148baa 100644
--- a/Userland/Applications/Piano/SamplerWidget.cpp
+++ b/Userland/Applications/Piano/SamplerWidget.cpp
@@ -52,11 +52,11 @@ SamplerWidget::SamplerWidget(TrackManager& track_manager)
     m_open_button->set_focus_policy(GUI::FocusPolicy::TabFocus);
     m_open_button->set_icon(Gfx::Bitmap::load_from_file("/res/icons/16x16/open.png"sv).release_value_but_fixme_should_propagate_errors());
     m_open_button->on_click = [this](auto) {
-        Optional<DeprecatedString> open_path = GUI::FilePicker::get_open_filepath(window());
+        Optional<ByteString> open_path = GUI::FilePicker::get_open_filepath(window());
         if (!open_path.has_value())
             return;
         // TODO: We don't actually load the sample.
-        m_recorded_sample_name->set_text(String::from_deprecated_string(open_path.value()).release_value_but_fixme_should_propagate_errors());
+        m_recorded_sample_name->set_text(String::from_byte_string(open_path.value()).release_value_but_fixme_should_propagate_errors());
         m_wave_editor->update();
     };
 
diff --git a/Userland/Applications/Piano/main.cpp b/Userland/Applications/Piano/main.cpp
index 496e1fe6da6..4131c0259b4 100644
--- a/Userland/Applications/Piano/main.cpp
+++ b/Userland/Applications/Piano/main.cpp
@@ -36,7 +36,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TrackManager track_manager;
 
     Threading::MutexProtected<Audio::WavWriter> wav_writer;
-    Optional<DeprecatedString> save_path;
+    Optional<ByteString> save_path;
     Atomic<bool> need_to_write_wav = false;
     Atomic<int> wav_percent_written = 0;
 
@@ -65,11 +65,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         save_path = GUI::FilePicker::get_save_filepath(window, "Untitled", "wav");
         if (!save_path.has_value())
             return;
-        DeprecatedString error;
+        ByteString error;
         wav_writer.with_locked([&](auto& wav_writer) {
             auto error_or_void = wav_writer.set_file(save_path.value());
             if (error_or_void.is_error())
-                error = DeprecatedString::formatted("Failed to export WAV file: {}", error_or_void.error());
+                error = ByteString::formatted("Failed to export WAV file: {}", error_or_void.error());
         });
         if (!error.is_empty()) {
             GUI::MessageBox::show_error(window, error);
diff --git a/Userland/Applications/PixelPaint/CreateNewImageDialog.cpp b/Userland/Applications/PixelPaint/CreateNewImageDialog.cpp
index 090fe6ae5d3..e23e65cae1e 100644
--- a/Userland/Applications/PixelPaint/CreateNewImageDialog.cpp
+++ b/Userland/Applications/PixelPaint/CreateNewImageDialog.cpp
@@ -121,7 +121,7 @@ CreateNewImageDialog::CreateNewImageDialog(GUI::Window* parent_window)
             Config::write_string("PixelPaint"sv, "NewImage"sv, "Name"sv, m_image_name);
             Config::write_i32("PixelPaint"sv, "NewImage"sv, "Width"sv, m_image_size.width());
             Config::write_i32("PixelPaint"sv, "NewImage"sv, "Height"sv, m_image_size.height());
-            Config::write_string("PixelPaint"sv, "NewImage"sv, "Background"sv, m_background_color.to_deprecated_string());
+            Config::write_string("PixelPaint"sv, "NewImage"sv, "Background"sv, m_background_color.to_byte_string());
         }
 
         done(ExecResult::OK);
diff --git a/Userland/Applications/PixelPaint/CreateNewImageDialog.h b/Userland/Applications/PixelPaint/CreateNewImageDialog.h
index a407a9e9d91..844f7d99515 100644
--- a/Userland/Applications/PixelPaint/CreateNewImageDialog.h
+++ b/Userland/Applications/PixelPaint/CreateNewImageDialog.h
@@ -16,13 +16,13 @@ class CreateNewImageDialog final : public GUI::Dialog {
 
 public:
     Gfx::IntSize image_size() const { return m_image_size; }
-    DeprecatedString const& image_name() const { return m_image_name; }
+    ByteString const& image_name() const { return m_image_name; }
     Gfx::Color background_color() const { return m_background_color; }
 
 private:
     CreateNewImageDialog(GUI::Window* parent_window);
 
-    DeprecatedString m_image_name;
+    ByteString m_image_name;
     Gfx::IntSize m_image_size;
     Gfx::Color m_background_color {};
 
diff --git a/Userland/Applications/PixelPaint/CreateNewLayerDialog.h b/Userland/Applications/PixelPaint/CreateNewLayerDialog.h
index 1c600e2407e..0844bd3acaf 100644
--- a/Userland/Applications/PixelPaint/CreateNewLayerDialog.h
+++ b/Userland/Applications/PixelPaint/CreateNewLayerDialog.h
@@ -15,7 +15,7 @@ class CreateNewLayerDialog final : public GUI::Dialog {
 
 public:
     Gfx::IntSize layer_size() const { return m_layer_size; }
-    DeprecatedString const& layer_name() const { return m_layer_name; }
+    ByteString const& layer_name() const { return m_layer_name; }
 
 private:
     static constexpr StringView default_layer_name = "Layer"sv;
@@ -23,7 +23,7 @@ private:
     CreateNewLayerDialog(Gfx::IntSize suggested_size, GUI::Window* parent_window);
 
     Gfx::IntSize m_layer_size;
-    DeprecatedString m_layer_name { default_layer_name };
+    ByteString m_layer_name { default_layer_name };
 
     RefPtr<GUI::TextBox> m_name_textbox;
 };
diff --git a/Userland/Applications/PixelPaint/EditGuideDialog.cpp b/Userland/Applications/PixelPaint/EditGuideDialog.cpp
index 8fb8d5f368d..eb49d6d9408 100644
--- a/Userland/Applications/PixelPaint/EditGuideDialog.cpp
+++ b/Userland/Applications/PixelPaint/EditGuideDialog.cpp
@@ -13,7 +13,7 @@
 
 namespace PixelPaint {
 
-EditGuideDialog::EditGuideDialog(GUI::Window* parent_window, DeprecatedString const& offset, Guide::Orientation orientation)
+EditGuideDialog::EditGuideDialog(GUI::Window* parent_window, ByteString const& offset, Guide::Orientation orientation)
     : Dialog(parent_window)
     , m_offset(offset)
     , m_orientation(orientation)
diff --git a/Userland/Applications/PixelPaint/EditGuideDialog.h b/Userland/Applications/PixelPaint/EditGuideDialog.h
index bdc31f6124c..a32f0d07647 100644
--- a/Userland/Applications/PixelPaint/EditGuideDialog.h
+++ b/Userland/Applications/PixelPaint/EditGuideDialog.h
@@ -16,15 +16,15 @@ class EditGuideDialog final : public GUI::Dialog {
     C_OBJECT(EditGuideDialog);
 
 public:
-    DeprecatedString const offset() const { return m_offset; }
+    ByteString const offset() const { return m_offset; }
     Guide::Orientation orientation() const { return m_orientation; }
 
     Optional<float> offset_as_pixel(ImageEditor const&);
 
 private:
-    EditGuideDialog(GUI::Window* parent_window, DeprecatedString const& offset = {}, Guide::Orientation orientation = Guide::Orientation::Unset);
+    EditGuideDialog(GUI::Window* parent_window, ByteString const& offset = {}, Guide::Orientation orientation = Guide::Orientation::Unset);
 
-    DeprecatedString m_offset;
+    ByteString m_offset;
     Guide::Orientation m_orientation;
     RefPtr<GUI::TextBox> m_offset_text_box;
     bool m_is_horizontal_checked { false };
diff --git a/Userland/Applications/PixelPaint/FilterTreeModel.h b/Userland/Applications/PixelPaint/FilterTreeModel.h
index 4853472b916..9464b6e4b15 100644
--- a/Userland/Applications/PixelPaint/FilterTreeModel.h
+++ b/Userland/Applications/PixelPaint/FilterTreeModel.h
@@ -16,7 +16,7 @@ namespace PixelPaint {
 
 class FilterNode final : public GUI::TreeViewModel::Node {
 public:
-    FilterNode(DeprecatedString text, Optional<GUI::Icon> icon, Node* parent_node, NonnullRefPtr<Filter> filter)
+    FilterNode(ByteString text, Optional<GUI::Icon> icon, Node* parent_node, NonnullRefPtr<Filter> filter)
         : Node(move(text), move(icon), parent_node)
         , m_filter(move(filter))
     {
diff --git a/Userland/Applications/PixelPaint/Image.cpp b/Userland/Applications/PixelPaint/Image.cpp
index 1e90c5815d2..7d2b9de8f9b 100644
--- a/Userland/Applications/PixelPaint/Image.cpp
+++ b/Userland/Applications/PixelPaint/Image.cpp
@@ -54,7 +54,7 @@ ErrorOr<NonnullRefPtr<Gfx::Bitmap>> Image::decode_bitmap(ReadonlyBytes bitmap_da
 {
     // Spawn a new ImageDecoder service process and connect to it.
     auto client = TRY(ImageDecoderClient::Client::try_create());
-    auto optional_mime_type = guessed_mime_type.map([](auto mime_type) { return mime_type.to_deprecated_string(); });
+    auto optional_mime_type = guessed_mime_type.map([](auto mime_type) { return mime_type.to_byte_string(); });
 
     // FIXME: Find a way to avoid the memory copying here.
     auto maybe_decoded_image = client->decode_image(bitmap_data, optional_mime_type);
@@ -85,14 +85,14 @@ ErrorOr<NonnullRefPtr<Image>> Image::create_from_pixel_paint_json(JsonObject con
     auto layers_value = json.get_array("layers"sv).value();
     for (auto& layer_value : layers_value.values()) {
         auto const& layer_object = layer_value.as_object();
-        auto name = layer_object.get_deprecated_string("name"sv).value();
+        auto name = layer_object.get_byte_string("name"sv).value();
 
-        auto bitmap_base64_encoded = layer_object.get_deprecated_string("bitmap"sv).value();
+        auto bitmap_base64_encoded = layer_object.get_byte_string("bitmap"sv).value();
         auto bitmap_data = TRY(decode_base64(bitmap_base64_encoded));
         auto bitmap = TRY(decode_bitmap(bitmap_data, {}));
         auto layer = TRY(Layer::create_with_bitmap(*image, move(bitmap), name));
 
-        if (auto const& mask_object = layer_object.get_deprecated_string("mask"sv); mask_object.has_value()) {
+        if (auto const& mask_object = layer_object.get_byte_string("mask"sv); mask_object.has_value()) {
             auto mask_base64_encoded = mask_object.value();
             auto mask_data = TRY(decode_base64(mask_base64_encoded));
             auto mask = TRY(decode_bitmap(mask_data, {}));
@@ -519,7 +519,7 @@ void Image::did_change_rect(Gfx::IntRect const& a_modified_rect)
         client->image_did_change_rect(modified_rect);
 }
 
-ImageUndoCommand::ImageUndoCommand(Image& image, DeprecatedString action_text)
+ImageUndoCommand::ImageUndoCommand(Image& image, ByteString action_text)
     : m_snapshot(image.take_snapshot().release_value_but_fixme_should_propagate_errors())
     , m_image(image)
     , m_action_text(move(action_text))
diff --git a/Userland/Applications/PixelPaint/Image.h b/Userland/Applications/PixelPaint/Image.h
index 001f597ac4e..736303343e0 100644
--- a/Userland/Applications/PixelPaint/Image.h
+++ b/Userland/Applications/PixelPaint/Image.h
@@ -136,16 +136,16 @@ private:
 
 class ImageUndoCommand : public GUI::Command {
 public:
-    ImageUndoCommand(Image&, DeprecatedString action_text);
+    ImageUndoCommand(Image&, ByteString action_text);
 
     virtual void undo() override;
     virtual void redo() override;
-    virtual DeprecatedString action_text() const override { return m_action_text; }
+    virtual ByteString action_text() const override { return m_action_text; }
 
 private:
     RefPtr<Image> m_snapshot;
     Image& m_image;
-    DeprecatedString m_action_text;
+    ByteString m_action_text;
 };
 
 }
diff --git a/Userland/Applications/PixelPaint/ImageEditor.cpp b/Userland/Applications/PixelPaint/ImageEditor.cpp
index 42c9e22193c..5d4c2d89863 100644
--- a/Userland/Applications/PixelPaint/ImageEditor.cpp
+++ b/Userland/Applications/PixelPaint/ImageEditor.cpp
@@ -34,7 +34,7 @@ ImageEditor::ImageEditor(NonnullRefPtr<Image> image)
     , m_gui_event_loop(Core::EventLoop::current())
 {
     set_focus_policy(GUI::FocusPolicy::StrongFocus);
-    m_undo_stack.push(make<ImageUndoCommand>(*m_image, DeprecatedString()));
+    m_undo_stack.push(make<ImageUndoCommand>(*m_image, ByteString()));
     m_image->add_client(*this);
     m_image->selection().add_client(*this);
     set_original_rect(m_image->rect());
@@ -61,7 +61,7 @@ ImageEditor::~ImageEditor()
     m_image->remove_client(*this);
 }
 
-void ImageEditor::did_complete_action(DeprecatedString action_text)
+void ImageEditor::did_complete_action(ByteString action_text)
 {
     set_modified(move(action_text));
 }
@@ -110,13 +110,13 @@ void ImageEditor::set_title(String title)
         on_title_change(m_title);
 }
 
-void ImageEditor::set_path(DeprecatedString path)
+void ImageEditor::set_path(ByteString path)
 {
     m_path = move(path);
-    set_title(String::from_deprecated_string(LexicalPath::title(m_path)).release_value_but_fixme_should_propagate_errors());
+    set_title(String::from_byte_string(LexicalPath::title(m_path)).release_value_but_fixme_should_propagate_errors());
 }
 
-void ImageEditor::set_modified(DeprecatedString action_text)
+void ImageEditor::set_modified(ByteString action_text)
 {
     m_undo_stack.push(make<ImageUndoCommand>(*m_image, move(action_text)));
     update_modified();
@@ -227,7 +227,7 @@ void ImageEditor::paint_event(GUI::PaintEvent& event)
 
             int const editor_x = content_to_frame_position({ x, 0 }).x();
             painter.draw_line({ editor_x, 0 }, { editor_x, m_ruler_thickness }, ruler_fg_color);
-            painter.draw_text(Gfx::IntRect { { editor_x + 2, 0 }, { m_ruler_thickness, m_ruler_thickness - 2 } }, DeprecatedString::formatted("{}", x), painter.font(), Gfx::TextAlignment::CenterLeft, ruler_text_color);
+            painter.draw_text(Gfx::IntRect { { editor_x + 2, 0 }, { m_ruler_thickness, m_ruler_thickness - 2 } }, ByteString::formatted("{}", x), painter.font(), Gfx::TextAlignment::CenterLeft, ruler_text_color);
         }
 
         // Vertical ruler
@@ -244,7 +244,7 @@ void ImageEditor::paint_event(GUI::PaintEvent& event)
 
             int const editor_y = content_to_frame_position({ 0, y }).y();
             painter.draw_line({ 0, editor_y }, { m_ruler_thickness, editor_y }, ruler_fg_color);
-            painter.draw_text(Gfx::IntRect { { 0, editor_y - m_ruler_thickness }, { m_ruler_thickness, m_ruler_thickness } }, DeprecatedString::formatted("{}", y), painter.font(), Gfx::TextAlignment::BottomRight, ruler_text_color);
+            painter.draw_text(Gfx::IntRect { { 0, editor_y - m_ruler_thickness }, { m_ruler_thickness, m_ruler_thickness } }, ByteString::formatted("{}", y), painter.font(), Gfx::TextAlignment::BottomRight, ruler_text_color);
         }
 
         // Mouse position indicator
@@ -360,7 +360,7 @@ void ImageEditor::set_status_info_to_color_at_mouse_position(Gfx::IntPoint posit
     if (!color.has_value())
         return;
 
-    set_appended_status_info(DeprecatedString::formatted("R:{}, G:{}, B:{}, A:{} [{}]", color->red(), color->green(), color->blue(), color->alpha(), color->to_deprecated_string()));
+    set_appended_status_info(ByteString::formatted("R:{}, G:{}, B:{}, A:{} [{}]", color->red(), color->green(), color->blue(), color->alpha(), color->to_byte_string()));
 }
 
 void ImageEditor::set_editor_color_to_color_at_mouse_position(GUI::MouseEvent const& event, bool sample_all_layers = false)
@@ -767,7 +767,7 @@ void ImageEditor::save_project()
 
 void ImageEditor::save_project_as()
 {
-    auto response = FileSystemAccessClient::Client::the().save_file(window(), m_title.to_deprecated_string(), "pp");
+    auto response = FileSystemAccessClient::Client::the().save_file(window(), m_title.to_byte_string(), "pp");
     if (response.is_error())
         return;
     auto file = response.release_value();
@@ -776,7 +776,7 @@ void ImageEditor::save_project_as()
         GUI::MessageBox::show_error(window(), MUST(String::formatted("Could not save {}: {}", file.filename(), result.release_error())));
         return;
     }
-    set_path(file.filename().to_deprecated_string());
+    set_path(file.filename().to_byte_string());
     set_loaded_from_image(false);
     set_unmodified();
 }
@@ -911,25 +911,25 @@ void ImageEditor::selection_did_change()
     update();
 }
 
-void ImageEditor::set_appended_status_info(DeprecatedString new_status_info)
+void ImageEditor::set_appended_status_info(ByteString new_status_info)
 {
     m_appended_status_info = new_status_info;
     if (on_appended_status_info_change)
         on_appended_status_info_change(m_appended_status_info);
 }
 
-DeprecatedString ImageEditor::generate_unique_layer_name(DeprecatedString const& original_layer_name)
+ByteString ImageEditor::generate_unique_layer_name(ByteString const& original_layer_name)
 {
     constexpr StringView copy_string_view = " copy"sv;
     auto copy_suffix_index = original_layer_name.find_last(copy_string_view);
     if (!copy_suffix_index.has_value())
-        return DeprecatedString::formatted("{}{}", original_layer_name, copy_string_view);
+        return ByteString::formatted("{}{}", original_layer_name, copy_string_view);
 
     auto after_copy_suffix_view = original_layer_name.substring_view(copy_suffix_index.value() + copy_string_view.length());
     if (!after_copy_suffix_view.is_empty()) {
         auto after_copy_suffix_number = after_copy_suffix_view.trim_whitespace().to_int();
         if (!after_copy_suffix_number.has_value())
-            return DeprecatedString::formatted("{}{}", original_layer_name, copy_string_view);
+            return ByteString::formatted("{}{}", original_layer_name, copy_string_view);
     }
 
     auto layer_with_name_exists = [this](auto name) {
@@ -948,7 +948,7 @@ DeprecatedString ImageEditor::generate_unique_layer_name(DeprecatedString const&
         new_layer_name.appendff("{}{} {}", base_layer_name, copy_string_view, ++duplicate_name_count);
     } while (layer_with_name_exists(new_layer_name.string_view()));
 
-    return new_layer_name.to_deprecated_string();
+    return new_layer_name.to_byte_string();
 }
 
 Gfx::IntRect ImageEditor::active_layer_visible_rect()
diff --git a/Userland/Applications/PixelPaint/ImageEditor.h b/Userland/Applications/PixelPaint/ImageEditor.h
index 46843f59baa..34eda4c4c00 100644
--- a/Userland/Applications/PixelPaint/ImageEditor.h
+++ b/Userland/Applications/PixelPaint/ImageEditor.h
@@ -44,14 +44,14 @@ public:
     void set_active_tool(Tool*);
     void update_tool_cursor();
 
-    void did_complete_action(DeprecatedString action_text);
+    void did_complete_action(ByteString action_text);
     bool undo();
     bool redo();
 
     auto& undo_stack() { return m_undo_stack; }
 
-    DeprecatedString const& path() const { return m_path; }
-    void set_path(DeprecatedString);
+    ByteString const& path() const { return m_path; }
+    void set_path(ByteString);
 
     String const& title() const { return m_title; }
     void set_title(String);
@@ -122,13 +122,13 @@ public:
     void set_status_info_to_color_at_mouse_position(Gfx::IntPoint position, bool sample_all_layers);
     void set_editor_color_to_color_at_mouse_position(GUI::MouseEvent const& event, bool sample_all_layers);
 
-    void set_modified(DeprecatedString action_text);
+    void set_modified(ByteString action_text);
     void set_unmodified();
     void update_modified();
-    Function<void(DeprecatedString)> on_appended_status_info_change;
-    DeprecatedString appended_status_info() { return m_appended_status_info; }
-    void set_appended_status_info(DeprecatedString);
-    DeprecatedString generate_unique_layer_name(DeprecatedString const& original_layer_name);
+    Function<void(ByteString)> on_appended_status_info_change;
+    ByteString appended_status_info() { return m_appended_status_info; }
+    void set_appended_status_info(ByteString);
+    ByteString generate_unique_layer_name(ByteString const& original_layer_name);
 
 private:
     explicit ImageEditor(NonnullRefPtr<Image>);
@@ -170,7 +170,7 @@ private:
     RefPtr<Layer> m_active_layer;
     GUI::UndoStack m_undo_stack;
 
-    DeprecatedString m_path;
+    ByteString m_path;
     String m_title;
 
     Vector<NonnullRefPtr<Guide>> m_guides;
@@ -202,7 +202,7 @@ private:
     void draw_marching_ants_pixel(Gfx::Painter&, int x, int y) const;
 
     Core::EventLoop& m_gui_event_loop;
-    DeprecatedString m_appended_status_info;
+    ByteString m_appended_status_info;
 };
 
 }
diff --git a/Userland/Applications/PixelPaint/ImageMasking.cpp b/Userland/Applications/PixelPaint/ImageMasking.cpp
index ffc3264d268..36af4963b78 100644
--- a/Userland/Applications/PixelPaint/ImageMasking.cpp
+++ b/Userland/Applications/PixelPaint/ImageMasking.cpp
@@ -378,7 +378,7 @@ void ColorWheelWidget::paint_event(GUI::PaintEvent&)
     aa_painter.fill_circle({ 0, 0 }, (height() - 4) / 4, Color::from_hsv(hue(), 1, 1));
 
     painter.restore();
-    auto hue_text = DeprecatedString::formatted("hue: {:.0}", hue());
+    auto hue_text = ByteString::formatted("hue: {:.0}", hue());
     painter.draw_text(rect().translated(1, 1), hue_text, Gfx::TextAlignment::Center, Color::Black);
     painter.draw_text(rect(), hue_text, Gfx::TextAlignment::Center, Color::White);
 }
diff --git a/Userland/Applications/PixelPaint/ImageProcessor.cpp b/Userland/Applications/PixelPaint/ImageProcessor.cpp
index 6cbb6907c6a..3f3dff5fc13 100644
--- a/Userland/Applications/PixelPaint/ImageProcessor.cpp
+++ b/Userland/Applications/PixelPaint/ImageProcessor.cpp
@@ -31,7 +31,7 @@ void FilterApplicationCommand::execute()
 
     m_filter->m_editor->gui_event_loop().deferred_invoke([strong_this = NonnullRefPtr(*this)]() {
         strong_this->m_target_layer->did_modify_bitmap(strong_this->m_target_layer->rect());
-        strong_this->m_filter->m_editor->did_complete_action(DeprecatedString::formatted("Filter {}", strong_this->m_filter->filter_name()));
+        strong_this->m_filter->m_editor->did_complete_action(ByteString::formatted("Filter {}", strong_this->m_filter->filter_name()));
     });
 }
 
diff --git a/Userland/Applications/PixelPaint/Layer.cpp b/Userland/Applications/PixelPaint/Layer.cpp
index 4c4f803a427..358d1bb6c62 100644
--- a/Userland/Applications/PixelPaint/Layer.cpp
+++ b/Userland/Applications/PixelPaint/Layer.cpp
@@ -18,7 +18,7 @@
 
 namespace PixelPaint {
 
-ErrorOr<NonnullRefPtr<Layer>> Layer::create_with_size(Image& image, Gfx::IntSize size, DeprecatedString name)
+ErrorOr<NonnullRefPtr<Layer>> Layer::create_with_size(Image& image, Gfx::IntSize size, ByteString name)
 {
     VERIFY(!size.is_empty());
 
@@ -29,7 +29,7 @@ ErrorOr<NonnullRefPtr<Layer>> Layer::create_with_size(Image& image, Gfx::IntSize
     return adopt_nonnull_ref_or_enomem(new (nothrow) Layer(image, move(bitmap), move(name)));
 }
 
-ErrorOr<NonnullRefPtr<Layer>> Layer::create_with_bitmap(Image& image, NonnullRefPtr<Gfx::Bitmap> bitmap, DeprecatedString name)
+ErrorOr<NonnullRefPtr<Layer>> Layer::create_with_bitmap(Image& image, NonnullRefPtr<Gfx::Bitmap> bitmap, ByteString name)
 {
     VERIFY(!bitmap->size().is_empty());
 
@@ -64,7 +64,7 @@ ErrorOr<NonnullRefPtr<Layer>> Layer::create_snapshot(Image& image, Layer const&
     return snapshot;
 }
 
-Layer::Layer(Image& image, NonnullRefPtr<Gfx::Bitmap> bitmap, DeprecatedString name)
+Layer::Layer(Image& image, NonnullRefPtr<Gfx::Bitmap> bitmap, ByteString name)
     : m_image(image)
     , m_name(move(name))
     , m_content_bitmap(move(bitmap))
@@ -112,7 +112,7 @@ void Layer::set_opacity_percent(int opacity_percent)
     m_image.layer_did_modify_properties({}, *this);
 }
 
-void Layer::set_name(DeprecatedString name)
+void Layer::set_name(ByteString name)
 {
     if (m_name == name)
         return;
@@ -486,7 +486,7 @@ Optional<Gfx::IntRect> Layer::editing_mask_bounding_rect() const
         *max_content_y - *min_content_y + 1
     };
 }
-ErrorOr<NonnullRefPtr<Layer>> Layer::duplicate(DeprecatedString name)
+ErrorOr<NonnullRefPtr<Layer>> Layer::duplicate(ByteString name)
 {
     auto duplicated_layer = TRY(Layer::create_snapshot(m_image, *this));
     duplicated_layer->m_name = move(name);
diff --git a/Userland/Applications/PixelPaint/Layer.h b/Userland/Applications/PixelPaint/Layer.h
index 75b86bf5027..aaccff395ce 100644
--- a/Userland/Applications/PixelPaint/Layer.h
+++ b/Userland/Applications/PixelPaint/Layer.h
@@ -9,7 +9,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Noncopyable.h>
 #include <AK/RefCounted.h>
 #include <AK/Weakable.h>
@@ -31,8 +31,8 @@ class Layer
     AK_MAKE_NONMOVABLE(Layer);
 
 public:
-    static ErrorOr<NonnullRefPtr<Layer>> create_with_size(Image&, Gfx::IntSize, DeprecatedString name);
-    static ErrorOr<NonnullRefPtr<Layer>> create_with_bitmap(Image&, NonnullRefPtr<Gfx::Bitmap>, DeprecatedString name);
+    static ErrorOr<NonnullRefPtr<Layer>> create_with_size(Image&, Gfx::IntSize, ByteString name);
+    static ErrorOr<NonnullRefPtr<Layer>> create_with_bitmap(Image&, NonnullRefPtr<Gfx::Bitmap>, ByteString name);
     static ErrorOr<NonnullRefPtr<Layer>> create_snapshot(Image&, Layer const&);
 
     ~Layer() = default;
@@ -68,8 +68,8 @@ public:
     Gfx::IntRect relative_rect() const { return { location(), size() }; }
     Gfx::IntRect rect() const { return { {}, size() }; }
 
-    DeprecatedString const& name() const { return m_name; }
-    void set_name(DeprecatedString);
+    ByteString const& name() const { return m_name; }
+    void set_name(ByteString);
 
     enum class NotifyClients {
         Yes,
@@ -116,7 +116,7 @@ public:
 
     Gfx::Bitmap& currently_edited_bitmap();
 
-    ErrorOr<NonnullRefPtr<Layer>> duplicate(DeprecatedString name);
+    ErrorOr<NonnullRefPtr<Layer>> duplicate(ByteString name);
 
     ALWAYS_INLINE Color modify_pixel_with_editing_mask(int x, int y, Color const& target_color, Color const& current_color)
     {
@@ -134,11 +134,11 @@ public:
     void on_second_paint(ImageEditor&);
 
 private:
-    Layer(Image&, NonnullRefPtr<Gfx::Bitmap>, DeprecatedString name);
+    Layer(Image&, NonnullRefPtr<Gfx::Bitmap>, ByteString name);
 
     Image& m_image;
 
-    DeprecatedString m_name;
+    ByteString m_name;
     Gfx::IntPoint m_location;
     NonnullRefPtr<Gfx::Bitmap> m_content_bitmap;
     RefPtr<Gfx::Bitmap> m_scratch_edited_bitmap { nullptr };
diff --git a/Userland/Applications/PixelPaint/MainWidget.cpp b/Userland/Applications/PixelPaint/MainWidget.cpp
index 29b35bc4d77..256d39e2f75 100644
--- a/Userland/Applications/PixelPaint/MainWidget.cpp
+++ b/Userland/Applications/PixelPaint/MainWidget.cpp
@@ -129,7 +129,7 @@ void MainWidget::image_editor_did_update_undo_stack()
             builder.append(' ');
             builder.append(suffix.value());
         }
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
 
     auto& undo_stack = image_editor->undo_stack();
@@ -141,7 +141,7 @@ void MainWidget::image_editor_did_update_undo_stack()
 }
 
 // Note: Update these together! v
-static Vector<DeprecatedString> const s_suggested_zoom_levels { "25%", "50%", "100%", "200%", "300%", "400%", "800%", "1600%", "Fit to width", "Fit to height", "Fit entire image" };
+static Vector<ByteString> const s_suggested_zoom_levels { "25%", "50%", "100%", "200%", "300%", "400%", "800%", "1600%", "Fit to width", "Fit to height", "Fit entire image" };
 static constexpr int s_zoom_level_fit_width = 8;
 static constexpr int s_zoom_level_fit_height = 9;
 static constexpr int s_zoom_level_fit_image = 10;
@@ -174,7 +174,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
 
                 auto& editor = create_new_editor(*image);
                 auto image_title = dialog->image_name().trim_whitespace();
-                editor.set_title((image_title.is_empty() ? "Untitled"_string : String::from_deprecated_string(image_title)).release_value_but_fixme_should_propagate_errors());
+                editor.set_title((image_title.is_empty() ? "Untitled"_string : String::from_byte_string(image_title)).release_value_but_fixme_should_propagate_errors());
                 editor.set_unmodified();
 
                 m_histogram_widget->set_image(image);
@@ -205,7 +205,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
         auto* editor = current_image_editor();
         VERIFY(editor);
         editor->save_project_as();
-        auto path_string = String::from_deprecated_string(editor->path()).release_value_but_fixme_should_propagate_errors();
+        auto path_string = String::from_byte_string(editor->path()).release_value_but_fixme_should_propagate_errors();
         GUI::Application::the()->set_most_recently_open_file(path_string);
     });
 
@@ -213,7 +213,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
         auto* editor = current_image_editor();
         VERIFY(editor);
         editor->save_project();
-        auto path_string = String::from_deprecated_string(editor->path()).release_value_but_fixme_should_propagate_errors();
+        auto path_string = String::from_byte_string(editor->path()).release_value_but_fixme_should_propagate_errors();
         GUI::Application::the()->set_most_recently_open_file(path_string);
     });
 
@@ -230,7 +230,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
             "As &BMP...", [&](auto&) {
                 auto* editor = current_image_editor();
                 VERIFY(editor);
-                auto response = FileSystemAccessClient::Client::the().save_file(&window, editor->title().to_deprecated_string(), "bmp");
+                auto response = FileSystemAccessClient::Client::the().save_file(&window, editor->title().to_byte_string(), "bmp");
                 if (response.is_error())
                     return;
                 auto preserve_alpha_channel = GUI::MessageBox::show(&window, "Do you wish to preserve transparency?"sv, "Preserve transparency?"sv, GUI::MessageBox::Type::Question, GUI::MessageBox::InputType::YesNo);
@@ -245,7 +245,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
                 auto* editor = current_image_editor();
                 VERIFY(editor);
                 // TODO: fix bmp on line below?
-                auto response = FileSystemAccessClient::Client::the().save_file(&window, editor->title().to_deprecated_string(), "png");
+                auto response = FileSystemAccessClient::Client::the().save_file(&window, editor->title().to_byte_string(), "png");
                 if (response.is_error())
                     return;
                 auto preserve_alpha_channel = GUI::MessageBox::show(&window, "Do you wish to preserve transparency?"sv, "Preserve transparency?"sv, GUI::MessageBox::Type::Question, GUI::MessageBox::InputType::YesNo);
@@ -259,7 +259,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
             "As &QOI...", [&](auto&) {
                 auto* editor = current_image_editor();
                 VERIFY(editor);
-                auto response = FileSystemAccessClient::Client::the().save_file(&window, editor->title().to_deprecated_string(), "qoi");
+                auto response = FileSystemAccessClient::Client::the().save_file(&window, editor->title().to_byte_string(), "qoi");
                 if (response.is_error())
                     return;
                 auto result = editor->image().export_qoi_to_file(response.value().release_stream());
@@ -325,9 +325,9 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
             return;
         }
         auto layer_rect = editor->active_layer()->relative_rect();
-        HashMap<DeprecatedString, DeprecatedString> layer_metadata;
-        layer_metadata.set("pixelpaint-layer-x", DeprecatedString::number(layer_rect.x()));
-        layer_metadata.set("pixelpaint-layer-y", DeprecatedString::number(layer_rect.y()));
+        HashMap<ByteString, ByteString> layer_metadata;
+        layer_metadata.set("pixelpaint-layer-x", ByteString::number(layer_rect.x()));
+        layer_metadata.set("pixelpaint-layer-y", ByteString::number(layer_rect.y()));
 
         GUI::Clipboard::the().set_bitmap(*bitmap, layer_metadata);
     });
@@ -1192,8 +1192,8 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
 
     m_zoom_combobox = toolbar.add<GUI::ComboBox>();
     m_zoom_combobox->set_max_width(75);
-    m_zoom_combobox->set_model(*GUI::ItemListModel<DeprecatedString>::create(s_suggested_zoom_levels));
-    m_zoom_combobox->on_change = [this](DeprecatedString const& value, GUI::ModelIndex const& index) {
+    m_zoom_combobox->set_model(*GUI::ItemListModel<ByteString>::create(s_suggested_zoom_levels));
+    m_zoom_combobox->on_change = [this](ByteString const& value, GUI::ModelIndex const& index) {
         auto* editor = current_image_editor();
         VERIFY(editor);
 
@@ -1295,7 +1295,7 @@ void MainWidget::open_image(FileSystemAccessClient::File file)
     auto& image = *m_loader.release_image();
     auto& editor = create_new_editor(image);
     editor.set_loaded_from_image(m_loader.is_raw_image());
-    editor.set_path(file.filename().to_deprecated_string());
+    editor.set_path(file.filename().to_byte_string());
     editor.set_unmodified();
     m_layer_list_widget->set_image(&image);
     GUI::Application::the()->set_most_recently_open_file(file.filename());
@@ -1415,7 +1415,7 @@ ImageEditor& MainWidget::create_new_editor(NonnullRefPtr<Image> image)
     };
 
     image_editor.on_scale_change = Core::debounce(100, [this](float scale) {
-        m_zoom_combobox->set_text(DeprecatedString::formatted("{}%", roundf(scale * 100)));
+        m_zoom_combobox->set_text(ByteString::formatted("{}%", roundf(scale * 100)));
         current_image_editor()->update_tool_cursor();
     });
 
@@ -1440,7 +1440,7 @@ ImageEditor& MainWidget::create_new_editor(NonnullRefPtr<Image> image)
             if (!value.is_object())
                 return;
             auto& json_object = value.as_object();
-            auto orientation_value = json_object.get_deprecated_string("orientation"sv);
+            auto orientation_value = json_object.get_byte_string("orientation"sv);
             if (!orientation_value.has_value())
                 return;
 
@@ -1502,10 +1502,10 @@ void MainWidget::update_window_modified()
 {
     window()->set_modified(m_tab_widget->is_any_tab_modified());
 }
-void MainWidget::update_status_bar(DeprecatedString appended_text)
+void MainWidget::update_status_bar(ByteString appended_text)
 {
     StringBuilder builder = StringBuilder();
-    builder.append(m_last_image_editor_mouse_position.to_deprecated_string());
+    builder.append(m_last_image_editor_mouse_position.to_byte_string());
     if (!appended_text.is_empty()) {
         builder.append(" "sv);
         builder.append(appended_text);
diff --git a/Userland/Applications/PixelPaint/MainWidget.h b/Userland/Applications/PixelPaint/MainWidget.h
index 46c6771693c..ccd4894ce39 100644
--- a/Userland/Applications/PixelPaint/MainWidget.h
+++ b/Userland/Applications/PixelPaint/MainWidget.h
@@ -62,7 +62,7 @@ private:
     virtual void drop_event(GUI::DropEvent&) override;
 
     void update_window_modified();
-    void update_status_bar(DeprecatedString appended_text = DeprecatedString::empty());
+    void update_status_bar(ByteString appended_text = ByteString::empty());
 
     ProjectLoader m_loader;
 
diff --git a/Userland/Applications/PixelPaint/PaletteWidget.cpp b/Userland/Applications/PixelPaint/PaletteWidget.cpp
index ddbbab69b38..9bc76cd8ce8 100644
--- a/Userland/Applications/PixelPaint/PaletteWidget.cpp
+++ b/Userland/Applications/PixelPaint/PaletteWidget.cpp
@@ -240,7 +240,7 @@ ErrorOr<Vector<Color>> PaletteWidget::load_palette_file(NonnullOwnPtr<Core::File
     return palette;
 }
 
-ErrorOr<Vector<Color>> PaletteWidget::load_palette_path(DeprecatedString const& file_path)
+ErrorOr<Vector<Color>> PaletteWidget::load_palette_path(ByteString const& file_path)
 {
     auto file = TRY(Core::File::open(file_path, Core::File::OpenMode::Read));
     return load_palette_file(move(file));
@@ -249,7 +249,7 @@ ErrorOr<Vector<Color>> PaletteWidget::load_palette_path(DeprecatedString const&
 ErrorOr<void> PaletteWidget::save_palette_file(Vector<Color> palette, NonnullOwnPtr<Core::File> file)
 {
     for (auto& color : palette) {
-        TRY(file->write_until_depleted(color.to_deprecated_string_without_alpha().bytes()));
+        TRY(file->write_until_depleted(color.to_byte_string_without_alpha().bytes()));
         TRY(file->write_until_depleted({ "\n", 1 }));
     }
     return {};
diff --git a/Userland/Applications/PixelPaint/PaletteWidget.h b/Userland/Applications/PixelPaint/PaletteWidget.h
index 362c29f5180..7825290fe07 100644
--- a/Userland/Applications/PixelPaint/PaletteWidget.h
+++ b/Userland/Applications/PixelPaint/PaletteWidget.h
@@ -32,7 +32,7 @@ public:
     Vector<Color> colors();
 
     static ErrorOr<Vector<Color>> load_palette_file(NonnullOwnPtr<Core::File>);
-    static ErrorOr<Vector<Color>> load_palette_path(DeprecatedString const&);
+    static ErrorOr<Vector<Color>> load_palette_path(ByteString const&);
     static ErrorOr<void> save_palette_file(Vector<Color>, NonnullOwnPtr<Core::File>);
 
     static Vector<Color> fallback_colors();
diff --git a/Userland/Applications/PixelPaint/ToolboxWidget.cpp b/Userland/Applications/PixelPaint/ToolboxWidget.cpp
index a4161282509..03dd21469e9 100644
--- a/Userland/Applications/PixelPaint/ToolboxWidget.cpp
+++ b/Userland/Applications/PixelPaint/ToolboxWidget.cpp
@@ -52,7 +52,7 @@ ToolboxWidget::ToolboxWidget()
 void ToolboxWidget::setup_tools()
 {
     auto add_tool = [&](StringView icon_name, GUI::Shortcut const& shortcut, NonnullOwnPtr<Tool> tool, bool is_default_tool = false) {
-        auto action = GUI::Action::create_checkable(tool->tool_name(), shortcut, Gfx::Bitmap::load_from_file(DeprecatedString::formatted("/res/icons/pixelpaint/{}.png", icon_name)).release_value_but_fixme_should_propagate_errors(),
+        auto action = GUI::Action::create_checkable(tool->tool_name(), shortcut, Gfx::Bitmap::load_from_file(ByteString::formatted("/res/icons/pixelpaint/{}.png", icon_name)).release_value_but_fixme_should_propagate_errors(),
             [this, tool = tool.ptr()](auto& action) {
                 if (action.is_checked()) {
                     on_tool_selection(tool);
diff --git a/Userland/Applications/PixelPaint/Tools/GuideTool.cpp b/Userland/Applications/PixelPaint/Tools/GuideTool.cpp
index 32dc1b04fb9..0a296ed5ee6 100644
--- a/Userland/Applications/PixelPaint/Tools/GuideTool.cpp
+++ b/Userland/Applications/PixelPaint/Tools/GuideTool.cpp
@@ -140,7 +140,7 @@ void GuideTool::on_context_menu(Layer*, GUI::ContextMenuEvent& event)
                     return;
                 auto dialog = EditGuideDialog::construct(
                     editor()->window(),
-                    DeprecatedString::formatted("{}", m_context_menu_guide->offset()),
+                    ByteString::formatted("{}", m_context_menu_guide->offset()),
                     m_context_menu_guide->orientation());
                 if (dialog->exec() != GUI::Dialog::ExecResult::OK)
                     return;
diff --git a/Userland/Applications/PixelPaint/Tools/RectangleSelectTool.cpp b/Userland/Applications/PixelPaint/Tools/RectangleSelectTool.cpp
index d622aa587d3..5f79fc9a2d9 100644
--- a/Userland/Applications/PixelPaint/Tools/RectangleSelectTool.cpp
+++ b/Userland/Applications/PixelPaint/Tools/RectangleSelectTool.cpp
@@ -209,7 +209,7 @@ NonnullRefPtr<GUI::Widget> RectangleSelectTool::get_properties_widget()
 
     auto& mode_combo = mode_container.add<GUI::ComboBox>();
     mode_combo.set_only_allow_values_from_model(true);
-    mode_combo.set_model(*GUI::ItemListModel<DeprecatedString>::create(m_merge_mode_names));
+    mode_combo.set_model(*GUI::ItemListModel<ByteString>::create(m_merge_mode_names));
     mode_combo.set_selected_index((int)m_merge_mode);
     mode_combo.on_change = [this](auto&&, GUI::ModelIndex const& index) {
         VERIFY(index.row() >= 0);
diff --git a/Userland/Applications/PixelPaint/Tools/RectangleSelectTool.h b/Userland/Applications/PixelPaint/Tools/RectangleSelectTool.h
index 0392f3f4697..6cc94fec107 100644
--- a/Userland/Applications/PixelPaint/Tools/RectangleSelectTool.h
+++ b/Userland/Applications/PixelPaint/Tools/RectangleSelectTool.h
@@ -40,7 +40,7 @@ private:
     };
 
     RefPtr<GUI::Widget> m_properties_widget;
-    Vector<DeprecatedString> m_merge_mode_names {};
+    Vector<ByteString> m_merge_mode_names {};
     Selection::MergeMode m_merge_mode { Selection::MergeMode::Set };
     float m_edge_feathering { 0.0f };
     bool m_selecting { false };
diff --git a/Userland/Applications/PixelPaint/Tools/WandSelectTool.cpp b/Userland/Applications/PixelPaint/Tools/WandSelectTool.cpp
index 1ba18e7a3e9..02bb870970e 100644
--- a/Userland/Applications/PixelPaint/Tools/WandSelectTool.cpp
+++ b/Userland/Applications/PixelPaint/Tools/WandSelectTool.cpp
@@ -122,7 +122,7 @@ NonnullRefPtr<GUI::Widget> WandSelectTool::get_properties_widget()
 
     auto& mode_combo = mode_container.add<GUI::ComboBox>();
     mode_combo.set_only_allow_values_from_model(true);
-    mode_combo.set_model(*GUI::ItemListModel<DeprecatedString>::create(m_merge_mode_names));
+    mode_combo.set_model(*GUI::ItemListModel<ByteString>::create(m_merge_mode_names));
     mode_combo.set_selected_index((int)m_merge_mode);
     mode_combo.on_change = [this](auto&&, GUI::ModelIndex const& index) {
         VERIFY(index.row() >= 0);
diff --git a/Userland/Applications/PixelPaint/Tools/WandSelectTool.h b/Userland/Applications/PixelPaint/Tools/WandSelectTool.h
index dd67eb00c72..beb9e9961fa 100644
--- a/Userland/Applications/PixelPaint/Tools/WandSelectTool.h
+++ b/Userland/Applications/PixelPaint/Tools/WandSelectTool.h
@@ -31,7 +31,7 @@ private:
 
     int m_threshold { 0 };
     RefPtr<GUI::Widget> m_properties_widget;
-    Vector<DeprecatedString> m_merge_mode_names {};
+    Vector<ByteString> m_merge_mode_names {};
     Selection::MergeMode m_merge_mode { Selection::MergeMode::Set };
 };
 
diff --git a/Userland/Applications/Presenter/Presentation.cpp b/Userland/Applications/Presenter/Presentation.cpp
index 7b53b02571f..73efdc46962 100644
--- a/Userland/Applications/Presenter/Presentation.cpp
+++ b/Userland/Applications/Presenter/Presentation.cpp
@@ -11,13 +11,13 @@
 #include <LibGUI/Window.h>
 #include <errno_codes.h>
 
-Presentation::Presentation(Gfx::IntSize normative_size, HashMap<DeprecatedString, DeprecatedString> metadata)
+Presentation::Presentation(Gfx::IntSize normative_size, HashMap<ByteString, ByteString> metadata)
     : m_normative_size(normative_size)
     , m_metadata(move(metadata))
 {
 }
 
-NonnullOwnPtr<Presentation> Presentation::construct(Gfx::IntSize normative_size, HashMap<DeprecatedString, DeprecatedString> metadata)
+NonnullOwnPtr<Presentation> Presentation::construct(Gfx::IntSize normative_size, HashMap<ByteString, ByteString> metadata)
 {
     return NonnullOwnPtr<Presentation>(NonnullOwnPtr<Presentation>::Adopt, *new Presentation(normative_size, move(metadata)));
 }
@@ -128,12 +128,12 @@ ErrorOr<NonnullOwnPtr<Presentation>> Presentation::load_from_file(StringView fil
     return presentation;
 }
 
-HashMap<DeprecatedString, DeprecatedString> Presentation::parse_metadata(JsonObject const& metadata_object)
+HashMap<ByteString, ByteString> Presentation::parse_metadata(JsonObject const& metadata_object)
 {
-    HashMap<DeprecatedString, DeprecatedString> metadata;
+    HashMap<ByteString, ByteString> metadata;
 
     metadata_object.for_each_member([&](auto const& key, auto const& value) {
-        metadata.set(key, value.to_deprecated_string());
+        metadata.set(key, value.to_byte_string());
     });
 
     return metadata;
@@ -142,7 +142,7 @@ HashMap<DeprecatedString, DeprecatedString> Presentation::parse_metadata(JsonObj
 ErrorOr<Gfx::IntSize> Presentation::parse_presentation_size(JsonObject const& metadata_object)
 {
     auto const& maybe_width = metadata_object.get("width"sv);
-    auto const& maybe_aspect = metadata_object.get_deprecated_string("aspect"sv);
+    auto const& maybe_aspect = metadata_object.get_byte_string("aspect"sv);
 
     if (!maybe_width.has_value() || !maybe_width->is_number() || !maybe_aspect.has_value())
         return Error::from_string_view("Width or aspect in incorrect format"sv);
@@ -164,14 +164,14 @@ ErrorOr<Gfx::IntSize> Presentation::parse_presentation_size(JsonObject const& me
     };
 }
 
-ErrorOr<DeprecatedString> Presentation::render()
+ErrorOr<ByteString> Presentation::render()
 {
     HTMLElement main_element;
     main_element.tag_name = "main"sv;
     for (size_t i = 0; i < m_slides.size(); ++i) {
         HTMLElement slide_div;
         slide_div.tag_name = "div"sv;
-        TRY(slide_div.attributes.try_set("id"sv, DeprecatedString::formatted("slide{}", i)));
+        TRY(slide_div.attributes.try_set("id"sv, ByteString::formatted("slide{}", i)));
         TRY(slide_div.attributes.try_set("class"sv, "slide hidden"sv));
         auto& slide = m_slides[i];
         TRY(slide_div.children.try_append(TRY(slide.render(*this))));
@@ -214,5 +214,5 @@ ErrorOr<DeprecatedString> Presentation::render()
 )"sv));
     TRY(main_element.serialize(builder));
     TRY(builder.try_append("</body></html>"sv));
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
diff --git a/Userland/Applications/Presenter/Presentation.h b/Userland/Applications/Presenter/Presentation.h
index 47cb07441bf..91fbca84233 100644
--- a/Userland/Applications/Presenter/Presentation.h
+++ b/Userland/Applications/Presenter/Presentation.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include "Slide.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/Vector.h>
@@ -38,21 +38,21 @@ public:
     void previous_frame();
     void go_to_first_slide();
 
-    ErrorOr<DeprecatedString> render();
+    ErrorOr<ByteString> render();
 
 private:
-    static HashMap<DeprecatedString, DeprecatedString> parse_metadata(JsonObject const& metadata_object);
+    static HashMap<ByteString, ByteString> parse_metadata(JsonObject const& metadata_object);
     static ErrorOr<Gfx::IntSize> parse_presentation_size(JsonObject const& metadata_object);
 
-    Presentation(Gfx::IntSize normative_size, HashMap<DeprecatedString, DeprecatedString> metadata);
-    static NonnullOwnPtr<Presentation> construct(Gfx::IntSize normative_size, HashMap<DeprecatedString, DeprecatedString> metadata);
+    Presentation(Gfx::IntSize normative_size, HashMap<ByteString, ByteString> metadata);
+    static NonnullOwnPtr<Presentation> construct(Gfx::IntSize normative_size, HashMap<ByteString, ByteString> metadata);
 
     void append_slide(Slide slide);
 
     Vector<Slide> m_slides {};
     // This is not a pixel size, but an abstract size used by the slide objects for relative positioning.
     Gfx::IntSize m_normative_size;
-    HashMap<DeprecatedString, DeprecatedString> m_metadata;
+    HashMap<ByteString, ByteString> m_metadata;
 
     Checked<unsigned> m_current_slide { 0 };
     Checked<unsigned> m_current_frame_in_slide { 0 };
diff --git a/Userland/Applications/Presenter/PresenterWidget.cpp b/Userland/Applications/Presenter/PresenterWidget.cpp
index acffb9a7b94..7118b66f6e9 100644
--- a/Userland/Applications/Presenter/PresenterWidget.cpp
+++ b/Userland/Applications/Presenter/PresenterWidget.cpp
@@ -125,7 +125,7 @@ ErrorOr<void> PresenterWidget::initialize_menubar()
 
 void PresenterWidget::update_web_view()
 {
-    m_web_view->run_javascript(DeprecatedString::formatted("goto({}, {})", m_current_presentation->current_slide_number(), m_current_presentation->current_frame_in_slide_number()));
+    m_web_view->run_javascript(ByteString::formatted("goto({}, {})", m_current_presentation->current_slide_number(), m_current_presentation->current_frame_in_slide_number()));
 }
 
 void PresenterWidget::update_slides_actions()
@@ -147,10 +147,10 @@ void PresenterWidget::set_file(StringView file_name)
 {
     auto presentation = Presentation::load_from_file(file_name);
     if (presentation.is_error()) {
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("The presentation \"{}\" could not be loaded.\n{}", file_name, presentation.error()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("The presentation \"{}\" could not be loaded.\n{}", file_name, presentation.error()));
     } else {
         m_current_presentation = presentation.release_value();
-        window()->set_title(DeprecatedString::formatted(title_template, m_current_presentation->title(), m_current_presentation->author()));
+        window()->set_title(ByteString::formatted(title_template, m_current_presentation->title(), m_current_presentation->author()));
         set_min_size(m_current_presentation->normative_size());
         m_web_view->load_html(MUST(m_current_presentation->render()));
         update_slides_actions();
diff --git a/Userland/Applications/Presenter/Slide.cpp b/Userland/Applications/Presenter/Slide.cpp
index b9b8e092136..db6684efd97 100644
--- a/Userland/Applications/Presenter/Slide.cpp
+++ b/Userland/Applications/Presenter/Slide.cpp
@@ -9,7 +9,7 @@
 #include "Presentation.h"
 #include <AK/JsonObject.h>
 
-Slide::Slide(unsigned frame_count, Vector<NonnullRefPtr<SlideObject>> slide_objects, DeprecatedString title)
+Slide::Slide(unsigned frame_count, Vector<NonnullRefPtr<SlideObject>> slide_objects, ByteString title)
     : m_frame_count(move(frame_count))
     , m_slide_objects(move(slide_objects))
     , m_title(move(title))
@@ -19,7 +19,7 @@ Slide::Slide(unsigned frame_count, Vector<NonnullRefPtr<SlideObject>> slide_obje
 ErrorOr<Slide> Slide::parse_slide(JsonObject const& slide_json, unsigned slide_index)
 {
     // FIXME: Use the text with the "title" role for a title, if there is no title given.
-    auto title = slide_json.get_deprecated_string("title"sv).value_or("Untitled slide");
+    auto title = slide_json.get_byte_string("title"sv).value_or("Untitled slide");
     auto frame_count = slide_json.get_u32("frame_count"sv).value_or(1);
     auto maybe_slide_objects = slide_json.get_array("objects"sv);
     if (!maybe_slide_objects.has_value())
diff --git a/Userland/Applications/Presenter/Slide.h b/Userland/Applications/Presenter/Slide.h
index 864cd4e4ec6..3baf5a420c2 100644
--- a/Userland/Applications/Presenter/Slide.h
+++ b/Userland/Applications/Presenter/Slide.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include "SlideObject.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 
 // A single slide of a presentation.
@@ -22,9 +22,9 @@ public:
     ErrorOr<HTMLElement> render(Presentation const&) const;
 
 private:
-    Slide(unsigned frame_count, Vector<NonnullRefPtr<SlideObject>> slide_objects, DeprecatedString title);
+    Slide(unsigned frame_count, Vector<NonnullRefPtr<SlideObject>> slide_objects, ByteString title);
 
     unsigned m_frame_count;
     Vector<NonnullRefPtr<SlideObject>> m_slide_objects;
-    DeprecatedString m_title;
+    ByteString m_title;
 };
diff --git a/Userland/Applications/Presenter/SlideObject.cpp b/Userland/Applications/Presenter/SlideObject.cpp
index 6576b5be880..3cf837ac60d 100644
--- a/Userland/Applications/Presenter/SlideObject.cpp
+++ b/Userland/Applications/Presenter/SlideObject.cpp
@@ -11,16 +11,16 @@
 #include <LibGfx/Font/FontStyleMapping.h>
 #include <LibGfx/Rect.h>
 
-static DeprecatedString to_css_length(float design_value, Presentation const& presentation)
+static ByteString to_css_length(float design_value, Presentation const& presentation)
 {
     float length_in_vw = design_value / static_cast<float>(presentation.normative_size().width()) * 100.0f;
-    return DeprecatedString::formatted("{}vw", length_in_vw);
+    return ByteString::formatted("{}vw", length_in_vw);
 }
 
 ErrorOr<NonnullRefPtr<SlideObject>> SlideObject::parse_slide_object(JsonObject const& slide_object_json, unsigned slide_index)
 {
     auto frame = slide_object_json.get_u32("frame"sv).value_or(0);
-    auto maybe_type = slide_object_json.get_deprecated_string("type"sv);
+    auto maybe_type = slide_object_json.get_byte_string("type"sv);
     if (!maybe_type.has_value())
         return Error::from_string_view("Slide object must have a type"sv);
 
@@ -58,7 +58,7 @@ void SlideObject::set_property(StringView name, JsonValue value)
 void GraphicsObject::set_property(StringView name, JsonValue value)
 {
     if (name == "color"sv) {
-        if (auto color = Gfx::Color::from_string(value.to_deprecated_string()); color.has_value()) {
+        if (auto color = Gfx::Color::from_string(value.to_byte_string()); color.has_value()) {
             m_color = color.release_value();
         }
     }
@@ -68,15 +68,15 @@ void GraphicsObject::set_property(StringView name, JsonValue value)
 void Text::set_property(StringView name, JsonValue value)
 {
     if (name == "text"sv) {
-        m_text = value.to_deprecated_string();
+        m_text = value.to_byte_string();
     } else if (name == "font"sv) {
-        m_font_family = value.to_deprecated_string();
+        m_font_family = value.to_byte_string();
     } else if (name == "font-weight"sv) {
-        m_font_weight = Gfx::name_to_weight(value.to_deprecated_string());
+        m_font_weight = Gfx::name_to_weight(value.to_byte_string());
     } else if (name == "font-size"sv) {
         m_font_size_in_pt = value.to_float();
     } else if (name == "text-alignment"sv) {
-        m_text_align = value.to_deprecated_string();
+        m_text_align = value.to_byte_string();
     }
     GraphicsObject::set_property(name, move(value));
 }
@@ -84,11 +84,11 @@ void Text::set_property(StringView name, JsonValue value)
 void Image::set_property(StringView name, JsonValue value)
 {
     if (name == "path"sv) {
-        m_src = value.to_deprecated_string();
+        m_src = value.to_byte_string();
     } else if (name == "scaling-mode"sv) {
-        if (value.to_deprecated_string() == "nearest-neighbor"sv)
+        if (value.to_byte_string() == "nearest-neighbor"sv)
             m_image_rendering = "crisp-edges"sv;
-        else if (value.to_deprecated_string() == "smooth-pixels"sv)
+        else if (value.to_byte_string() == "smooth-pixels"sv)
             m_image_rendering = "pixelated"sv;
     }
     SlideObject::set_property(name, move(value));
@@ -98,11 +98,11 @@ ErrorOr<HTMLElement> Text::render(Presentation const& presentation) const
 {
     HTMLElement div;
     div.tag_name = "div"sv;
-    TRY(div.attributes.try_set("class"sv, DeprecatedString::formatted("frame slide{}-frame{}", m_slide_index, m_frame_index)));
-    div.style.set("color"sv, m_color.to_deprecated_string());
-    div.style.set("font-family"sv, DeprecatedString::formatted("'{}'", m_font_family));
+    TRY(div.attributes.try_set("class"sv, ByteString::formatted("frame slide{}-frame{}", m_slide_index, m_frame_index)));
+    div.style.set("color"sv, m_color.to_byte_string());
+    div.style.set("font-family"sv, ByteString::formatted("'{}'", m_font_family));
     div.style.set("font-size"sv, to_css_length(m_font_size_in_pt * 1.33333333f, presentation));
-    div.style.set("font-weight"sv, DeprecatedString::number(m_font_weight));
+    div.style.set("font-weight"sv, ByteString::number(m_font_weight));
     div.style.set("text-align"sv, m_text_align);
     div.style.set("white-space"sv, "pre-wrap"sv);
     div.style.set("width"sv, to_css_length(m_rect.width(), presentation));
@@ -118,7 +118,7 @@ ErrorOr<HTMLElement> Image::render(Presentation const& presentation) const
 {
     HTMLElement img;
     img.tag_name = "img"sv;
-    img.attributes.set("src"sv, URL::create_with_file_scheme(m_src).to_deprecated_string());
+    img.attributes.set("src"sv, URL::create_with_file_scheme(m_src).to_byte_string());
     img.style.set("image-rendering"sv, m_image_rendering);
     if (m_rect.width() > m_rect.height())
         img.style.set("height"sv, "100%"sv);
@@ -127,7 +127,7 @@ ErrorOr<HTMLElement> Image::render(Presentation const& presentation) const
 
     HTMLElement image_wrapper;
     image_wrapper.tag_name = "div"sv;
-    TRY(image_wrapper.attributes.try_set("class"sv, DeprecatedString::formatted("frame slide{}-frame{}", m_slide_index, m_frame_index)));
+    TRY(image_wrapper.attributes.try_set("class"sv, ByteString::formatted("frame slide{}-frame{}", m_slide_index, m_frame_index)));
     image_wrapper.children.append(move(img));
     image_wrapper.style.set("position"sv, "absolute"sv);
     image_wrapper.style.set("left"sv, to_css_length(m_rect.left(), presentation));
diff --git a/Userland/Applications/Presenter/SlideObject.h b/Userland/Applications/Presenter/SlideObject.h
index 1936f84d466..cd12416e417 100644
--- a/Userland/Applications/Presenter/SlideObject.h
+++ b/Userland/Applications/Presenter/SlideObject.h
@@ -14,9 +14,9 @@ class Presentation;
 
 struct HTMLElement {
     StringView tag_name;
-    HashMap<StringView, DeprecatedString> attributes;
-    HashMap<StringView, DeprecatedString> style;
-    DeprecatedString inner_text;
+    HashMap<StringView, ByteString> attributes;
+    HashMap<StringView, ByteString> style;
+    ByteString inner_text;
     Vector<HTMLElement> children;
 
     ErrorOr<void> serialize(StringBuilder&) const;
@@ -44,7 +44,7 @@ protected:
 
     unsigned m_frame_index;
     unsigned m_slide_index;
-    HashMap<DeprecatedString, JsonValue> m_properties;
+    HashMap<ByteString, JsonValue> m_properties;
     Gfx::IntRect m_rect;
 };
 
@@ -76,9 +76,9 @@ private:
     virtual ErrorOr<HTMLElement> render(Presentation const&) const override;
     virtual void set_property(StringView name, JsonValue) override;
 
-    DeprecatedString m_text;
-    DeprecatedString m_font_family;
-    DeprecatedString m_text_align;
+    ByteString m_text;
+    ByteString m_font_family;
+    ByteString m_text_align;
     float m_font_size_in_pt { 18 };
     unsigned m_font_weight { Gfx::FontWeight::Regular };
 };
@@ -92,7 +92,7 @@ public:
     virtual ~Image() = default;
 
 private:
-    DeprecatedString m_src;
+    ByteString m_src;
     StringView m_image_rendering;
 
     virtual ErrorOr<HTMLElement> render(Presentation const&) const override;
diff --git a/Userland/Applications/Presenter/main.cpp b/Userland/Applications/Presenter/main.cpp
index 9526276caaa..d49fc9b303c 100644
--- a/Userland/Applications/Presenter/main.cpp
+++ b/Userland/Applications/Presenter/main.cpp
@@ -18,7 +18,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     // rpath is required to load .presenter files, unix, sendfd and recvfd are required to talk to WindowServer and WebContent.
     TRY(Core::System::pledge("stdio rpath unix sendfd recvfd"));
 
-    DeprecatedString file_to_load;
+    ByteString file_to_load;
     Core::ArgsParser argument_parser;
     argument_parser.add_positional_argument(file_to_load, "Presentation to load", "file", Core::ArgsParser::Required::No);
     argument_parser.parse(arguments);
diff --git a/Userland/Applications/Run/RunWindow.cpp b/Userland/Applications/Run/RunWindow.cpp
index de3ab1c3a28..2b8246bff53 100644
--- a/Userland/Applications/Run/RunWindow.cpp
+++ b/Userland/Applications/Run/RunWindow.cpp
@@ -28,7 +28,7 @@
 
 RunWindow::RunWindow()
     : m_path_history()
-    , m_path_history_model(GUI::ItemListModel<DeprecatedString>::create(m_path_history))
+    , m_path_history_model(GUI::ItemListModel<ByteString>::create(m_path_history))
 {
     // FIXME: Handle failure to load history somehow.
     (void)load_history();
@@ -65,7 +65,7 @@ RunWindow::RunWindow()
 
     m_browse_button = *find_descendant_of_type_named<GUI::DialogButton>("browse_button");
     m_browse_button->on_click = [this](auto) {
-        Optional<DeprecatedString> path = GUI::FilePicker::get_open_filepath(this, {}, Core::StandardPaths::home_directory(), false, GUI::Dialog::ScreenPosition::Center);
+        Optional<ByteString> path = GUI::FilePicker::get_open_filepath(this, {}, Core::StandardPaths::home_directory(), false, GUI::Dialog::ScreenPosition::Center);
         if (path.has_value())
             m_path_combo_box->set_text(path.value().view());
     };
@@ -95,7 +95,7 @@ void RunWindow::do_run()
 
     if (run_via_launch(run_input) || run_as_command(run_input)) {
         // Remove any existing history entry, prepend the successful run string to history and save.
-        m_path_history.remove_all_matching([&](DeprecatedString v) { return v == run_input; });
+        m_path_history.remove_all_matching([&](ByteString v) { return v == run_input; });
         m_path_history.prepend(run_input);
         // FIXME: Handle failure to save history somehow.
         (void)save_history();
@@ -109,7 +109,7 @@ void RunWindow::do_run()
     show();
 }
 
-bool RunWindow::run_as_command(DeprecatedString const& run_input)
+bool RunWindow::run_as_command(ByteString const& run_input)
 {
     // TODO: Query and use the user's preferred shell.
     auto maybe_child_pid = Core::Process::spawn("/bin/Shell"sv, Array { "-c", run_input.characters() }, {}, Core::Process::KeepAsChild::Yes);
@@ -136,7 +136,7 @@ bool RunWindow::run_as_command(DeprecatedString const& run_input)
     return true;
 }
 
-bool RunWindow::run_via_launch(DeprecatedString const& run_input)
+bool RunWindow::run_via_launch(ByteString const& run_input)
 {
     auto url = URL::create_with_url_or_path(run_input);
 
@@ -147,7 +147,7 @@ bool RunWindow::run_via_launch(DeprecatedString const& run_input)
             warnln("Failed to launch '{}': {}", file_path, real_path_or_error.error());
             return false;
         }
-        url = URL::create_with_url_or_path(real_path_or_error.release_value().to_deprecated_string());
+        url = URL::create_with_url_or_path(real_path_or_error.release_value().to_byte_string());
     }
 
     if (!Desktop::Launcher::open(url)) {
@@ -160,9 +160,9 @@ bool RunWindow::run_via_launch(DeprecatedString const& run_input)
     return true;
 }
 
-DeprecatedString RunWindow::history_file_path()
+ByteString RunWindow::history_file_path()
 {
-    return LexicalPath::canonicalized_path(DeprecatedString::formatted("{}/{}", Core::StandardPaths::config_directory(), "RunHistory.txt"));
+    return LexicalPath::canonicalized_path(ByteString::formatted("{}/{}", Core::StandardPaths::config_directory(), "RunHistory.txt"));
 }
 
 ErrorOr<void> RunWindow::load_history()
@@ -186,7 +186,7 @@ ErrorOr<void> RunWindow::save_history()
 
     // Write the first 25 items of history
     for (int i = 0; i < min(static_cast<int>(m_path_history.size()), 25); i++)
-        TRY(file->write_until_depleted(DeprecatedString::formatted("{}\n", m_path_history[i]).bytes()));
+        TRY(file->write_until_depleted(ByteString::formatted("{}\n", m_path_history[i]).bytes()));
 
     return {};
 }
diff --git a/Userland/Applications/Run/RunWindow.h b/Userland/Applications/Run/RunWindow.h
index 28694073936..9c3076ce1b4 100644
--- a/Userland/Applications/Run/RunWindow.h
+++ b/Userland/Applications/Run/RunWindow.h
@@ -24,15 +24,15 @@ private:
     RunWindow();
 
     void do_run();
-    bool run_as_command(DeprecatedString const& run_input);
-    bool run_via_launch(DeprecatedString const& run_input);
+    bool run_as_command(ByteString const& run_input);
+    bool run_via_launch(ByteString const& run_input);
 
-    DeprecatedString history_file_path();
+    ByteString history_file_path();
     ErrorOr<void> load_history();
     ErrorOr<void> save_history();
 
-    Vector<DeprecatedString> m_path_history;
-    NonnullRefPtr<GUI::ItemListModel<DeprecatedString>> m_path_history_model;
+    Vector<ByteString> m_path_history;
+    NonnullRefPtr<GUI::ItemListModel<ByteString>> m_path_history_model;
 
     RefPtr<GUI::ImageWidget> m_icon_image_widget;
     RefPtr<GUI::Button> m_ok_button;
diff --git a/Userland/Applications/Settings/main.cpp b/Userland/Applications/Settings/main.cpp
index c53a052f383..1e1e9433367 100644
--- a/Userland/Applications/Settings/main.cpp
+++ b/Userland/Applications/Settings/main.cpp
@@ -55,7 +55,7 @@ public:
             return app->icon();
 
         if (role == GUI::ModelRole::Display) {
-            DeprecatedString name;
+            ByteString name;
 
             if (app->name().ends_with(" Settings"sv))
                 name = app->name().substring(0, app->name().length() - " Settings"sv.length());
@@ -115,7 +115,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         auto requires_root = model->data(index, static_cast<GUI::ModelRole>(SettingsAppsModelCustomRole::RequiresRoot)).as_bool();
 
         auto launch_origin_rect = icon_view.to_widget_rect(icon_view.content_rect(index)).translated(icon_view.screen_relative_rect().location());
-        setenv("__libgui_launch_origin_rect", DeprecatedString::formatted("{},{},{},{}", launch_origin_rect.x(), launch_origin_rect.y(), launch_origin_rect.width(), launch_origin_rect.height()).characters(), 1);
+        setenv("__libgui_launch_origin_rect", ByteString::formatted("{},{},{},{}", launch_origin_rect.x(), launch_origin_rect.y(), launch_origin_rect.width(), launch_origin_rect.height()).characters(), 1);
 
         if (requires_root)
             GUI::Process::spawn_or_show_error(window, "/bin/Escalator"sv, Array { executable });
@@ -133,7 +133,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         }
 
         auto& app = *(NonnullRefPtr<Desktop::AppFile>*)index.internal_data();
-        statusbar.set_text(String::from_deprecated_string(app->description()).release_value_but_fixme_should_propagate_errors());
+        statusbar.set_text(String::from_byte_string(app->description()).release_value_but_fixme_should_propagate_errors());
     };
 
     window->set_icon(app_icon.bitmap_for_size(16));
diff --git a/Userland/Applications/SoundPlayer/M3UParser.cpp b/Userland/Applications/SoundPlayer/M3UParser.cpp
index a5778592ebd..65c15c9feb0 100644
--- a/Userland/Applications/SoundPlayer/M3UParser.cpp
+++ b/Userland/Applications/SoundPlayer/M3UParser.cpp
@@ -20,10 +20,10 @@ NonnullOwnPtr<M3UParser> M3UParser::from_file(StringView path)
     auto file_result = Core::File::open(path, Core::File::OpenMode::Read).release_value_but_fixme_should_propagate_errors();
     auto contents = file_result->read_until_eof().release_value_but_fixme_should_propagate_errors();
     auto use_utf8 = path.ends_with(".m3u8"sv, CaseSensitivity::CaseInsensitive);
-    return from_memory(DeprecatedString { contents, NoChomp }, use_utf8);
+    return from_memory(ByteString { contents, NoChomp }, use_utf8);
 }
 
-NonnullOwnPtr<M3UParser> M3UParser::from_memory(DeprecatedString const& m3u_contents, bool utf8)
+NonnullOwnPtr<M3UParser> M3UParser::from_memory(ByteString const& m3u_contents, bool utf8)
 {
     auto parser = make<M3UParser>();
     VERIFY(!m3u_contents.is_empty() && !m3u_contents.is_whitespace());
diff --git a/Userland/Applications/SoundPlayer/M3UParser.h b/Userland/Applications/SoundPlayer/M3UParser.h
index 39e33e79db8..4bfc8381121 100644
--- a/Userland/Applications/SoundPlayer/M3UParser.h
+++ b/Userland/Applications/SoundPlayer/M3UParser.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <AK/RefPtr.h>
 #include <AK/StringView.h>
@@ -15,35 +15,35 @@
 // Extended M3U fields (de facto standard)
 struct M3UExtendedInfo {
     Optional<u32> track_length_in_seconds;
-    Optional<DeprecatedString> track_display_title;
-    Optional<DeprecatedString> group_name;
-    Optional<DeprecatedString> album_title;
-    Optional<DeprecatedString> album_artist;
-    Optional<DeprecatedString> album_genre;
+    Optional<ByteString> track_display_title;
+    Optional<ByteString> group_name;
+    Optional<ByteString> album_title;
+    Optional<ByteString> album_artist;
+    Optional<ByteString> album_genre;
     Optional<u64> file_size_in_bytes;
     Optional<ReadonlyBytes> embedded_mp3;
-    Optional<DeprecatedString> cover_path;
+    Optional<ByteString> cover_path;
 };
 
 struct M3UEntry {
-    DeprecatedString path;
+    ByteString path;
     Optional<M3UExtendedInfo> extended_info;
 };
 
 class M3UParser {
 public:
     static NonnullOwnPtr<M3UParser> from_file(StringView path);
-    static NonnullOwnPtr<M3UParser> from_memory(DeprecatedString const& m3u_contents, bool utf8);
+    static NonnullOwnPtr<M3UParser> from_memory(ByteString const& m3u_contents, bool utf8);
 
     NonnullOwnPtr<Vector<M3UEntry>> parse(bool include_extended_info);
 
-    Optional<DeprecatedString>& get_playlist_title_metadata() { return m_parsed_playlist_title; }
+    Optional<ByteString>& get_playlist_title_metadata() { return m_parsed_playlist_title; }
 
     M3UParser();
 
 private:
-    DeprecatedString m_m3u_raw_data;
-    DeprecatedString m_playlist_path;
+    ByteString m_m3u_raw_data;
+    ByteString m_playlist_path;
     bool m_use_utf8;
-    Optional<DeprecatedString> m_parsed_playlist_title;
+    Optional<ByteString> m_parsed_playlist_title;
 };
diff --git a/Userland/Applications/SoundPlayer/Player.cpp b/Userland/Applications/SoundPlayer/Player.cpp
index 3ff8c2ae891..1017de350e6 100644
--- a/Userland/Applications/SoundPlayer/Player.cpp
+++ b/Userland/Applications/SoundPlayer/Player.cpp
@@ -38,7 +38,7 @@ Player::Player(Audio::ConnectionToServer& audio_client_connection)
     };
 }
 
-void Player::play_file_path(DeprecatedString const& path)
+void Player::play_file_path(ByteString const& path)
 {
     if (!FileSystem::exists(path)) {
         audio_load_error(path, "File does not exist"sv);
@@ -66,7 +66,7 @@ void Player::play_file_path(DeprecatedString const& path)
     play();
 }
 
-bool Player::is_playlist(DeprecatedString const& path)
+bool Player::is_playlist(ByteString const& path)
 {
     return (path.ends_with(".m3u"sv, AK::CaseSensitivity::CaseInsensitive)
         || path.ends_with(".m3u8"sv, AK::CaseSensitivity::CaseInsensitive));
diff --git a/Userland/Applications/SoundPlayer/Player.h b/Userland/Applications/SoundPlayer/Player.h
index f0b27655337..f3cab748edf 100644
--- a/Userland/Applications/SoundPlayer/Player.h
+++ b/Userland/Applications/SoundPlayer/Player.h
@@ -35,12 +35,12 @@ public:
     explicit Player(Audio::ConnectionToServer& audio_client_connection);
     virtual ~Player() = default;
 
-    void play_file_path(DeprecatedString const& path);
-    bool is_playlist(DeprecatedString const& path);
+    void play_file_path(ByteString const& path);
+    bool is_playlist(ByteString const& path);
 
     Playlist& playlist() { return m_playlist; }
     PlaybackManager const& playback_manager() const { return m_playback_manager; }
-    DeprecatedString const& loaded_filename() const { return m_loaded_filename; }
+    ByteString const& loaded_filename() const { return m_loaded_filename; }
 
     PlayState play_state() const { return m_play_state; }
     void set_play_state(PlayState);
@@ -98,7 +98,7 @@ private:
     Audio::ConnectionToServer& m_audio_client_connection;
     PlaybackManager m_playback_manager;
 
-    DeprecatedString m_loaded_filename;
+    ByteString m_loaded_filename;
     double m_volume { 0 };
     bool m_muted { false };
 };
diff --git a/Userland/Applications/SoundPlayer/Playlist.cpp b/Userland/Applications/SoundPlayer/Playlist.cpp
index 6e841291eda..5454e853229 100644
--- a/Userland/Applications/SoundPlayer/Playlist.cpp
+++ b/Userland/Applications/SoundPlayer/Playlist.cpp
@@ -36,7 +36,7 @@ void Playlist::try_fill_missing_info(Vector<M3UEntry>& entries, StringView path)
 
     for (auto& entry : entries) {
         if (!LexicalPath { entry.path }.is_absolute())
-            entry.path = DeprecatedString::formatted("{}/{}", playlist_path.dirname(), entry.path);
+            entry.path = ByteString::formatted("{}/{}", playlist_path.dirname(), entry.path);
 
         if (!entry.extended_info->file_size_in_bytes.has_value()) {
             auto size = FileSystem::size(entry.path);
diff --git a/Userland/Applications/SoundPlayer/SoundPlayerWidget.cpp b/Userland/Applications/SoundPlayer/SoundPlayerWidget.cpp
index 1ead9c70d4a..d30e53a8314 100644
--- a/Userland/Applications/SoundPlayer/SoundPlayerWidget.cpp
+++ b/Userland/Applications/SoundPlayer/SoundPlayerWidget.cpp
@@ -11,7 +11,7 @@
 #include "M3UParser.h"
 #include "PlaybackManager.h"
 #include "SampleWidget.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/NumberFormat.h>
 #include <AK/SIMD.h>
@@ -250,17 +250,17 @@ void SoundPlayerWidget::time_elapsed(int seconds)
 void SoundPlayerWidget::file_name_changed(StringView name)
 {
     m_visualization->start_new_file(name);
-    DeprecatedString title = name;
+    ByteString title = name;
     if (playback_manager().loader()) {
         auto const& metadata = playback_manager().loader()->metadata();
         if (auto artists_or_error = metadata.all_artists(" / "_string);
             !artists_or_error.is_error() && artists_or_error.value().has_value() && metadata.title.has_value()) {
-            title = DeprecatedString::formatted("{} – {}", metadata.title.value(), artists_or_error.release_value().release_value());
+            title = ByteString::formatted("{} – {}", metadata.title.value(), artists_or_error.release_value().release_value());
         } else if (metadata.title.has_value()) {
-            title = metadata.title.value().to_deprecated_string();
+            title = metadata.title.value().to_byte_string();
         }
     }
-    m_window.set_title(DeprecatedString::formatted("{} — Sound Player", title));
+    m_window.set_title(ByteString::formatted("{} — Sound Player", title));
 }
 
 void SoundPlayerWidget::total_samples_changed(int total_samples)
@@ -286,7 +286,7 @@ void SoundPlayerWidget::volume_changed(double volume)
 void SoundPlayerWidget::playlist_loaded(StringView path, bool loaded)
 {
     if (!loaded) {
-        GUI::MessageBox::show(&m_window, DeprecatedString::formatted("Could not load playlist at \"{}\".", path), "Error opening playlist"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(&m_window, ByteString::formatted("Could not load playlist at \"{}\".", path), "Error opening playlist"sv, GUI::MessageBox::Type::Error);
         return;
     }
     set_playlist_visible(true);
@@ -295,6 +295,6 @@ void SoundPlayerWidget::playlist_loaded(StringView path, bool loaded)
 
 void SoundPlayerWidget::audio_load_error(StringView path, StringView error_string)
 {
-    GUI::MessageBox::show(&m_window, DeprecatedString::formatted("Failed to load audio file: {} ({})", path, error_string.is_null() ? "Unknown error"sv : error_string),
+    GUI::MessageBox::show(&m_window, ByteString::formatted("Failed to load audio file: {} ({})", path, error_string.is_null() ? "Unknown error"sv : error_string),
         "Filetype error"sv, GUI::MessageBox::Type::Error);
 }
diff --git a/Userland/Applications/SoundPlayer/main.cpp b/Userland/Applications/SoundPlayer/main.cpp
index 35d394302e2..83206096d1e 100644
--- a/Userland/Applications/SoundPlayer/main.cpp
+++ b/Userland/Applications/SoundPlayer/main.cpp
@@ -62,7 +62,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto file_menu = window->add_menu("&File"_string);
     file_menu->add_action(GUI::CommonActions::make_open_action([&](auto&) {
-        Optional<DeprecatedString> path = GUI::FilePicker::get_open_filepath(window);
+        Optional<ByteString> path = GUI::FilePicker::get_open_filepath(window);
         if (path.has_value()) {
             player->play_file_path(path.value());
         }
diff --git a/Userland/Applications/SpaceAnalyzer/Tree.cpp b/Userland/Applications/SpaceAnalyzer/Tree.cpp
index 39edea37723..2e010f7f0fb 100644
--- a/Userland/Applications/SpaceAnalyzer/Tree.cpp
+++ b/Userland/Applications/SpaceAnalyzer/Tree.cpp
@@ -40,19 +40,19 @@ void TreeNode::sort_children_by_area() const
 }
 
 struct QueueEntry {
-    QueueEntry(DeprecatedString path, TreeNode* node)
+    QueueEntry(ByteString path, TreeNode* node)
         : path(move(path))
         , node(node) {};
-    DeprecatedString path;
+    ByteString path;
     TreeNode* node { nullptr };
 };
 
-static MountInfo* find_mount_for_path(DeprecatedString path, Vector<MountInfo>& mounts)
+static MountInfo* find_mount_for_path(ByteString path, Vector<MountInfo>& mounts)
 {
     MountInfo* result = nullptr;
     size_t length = 0;
     for (auto& mount_info : mounts) {
-        DeprecatedString& mount_point = mount_info.mount_point;
+        ByteString& mount_point = mount_info.mount_point;
         if (path.starts_with(mount_point)) {
             if (!result || mount_point.length() > length) {
                 result = &mount_info;
@@ -81,7 +81,7 @@ HashMap<int, int> TreeNode::populate_filesize_tree(Vector<MountInfo>& mounts, Fu
     StringBuilder builder = StringBuilder();
     builder.append(m_name);
     builder.append('/');
-    MountInfo* root_mount_info = find_mount_for_path(builder.to_deprecated_string(), mounts);
+    MountInfo* root_mount_info = find_mount_for_path(builder.to_byte_string(), mounts);
     if (!root_mount_info) {
         return error_accumulator;
     }
@@ -92,7 +92,7 @@ HashMap<int, int> TreeNode::populate_filesize_tree(Vector<MountInfo>& mounts, Fu
         builder.append(queue_entry.path);
         builder.append('/');
 
-        MountInfo* mount_info = find_mount_for_path(builder.to_deprecated_string(), mounts);
+        MountInfo* mount_info = find_mount_for_path(builder.to_byte_string(), mounts);
         if (!mount_info || (mount_info != root_mount_info && mount_info->source != root_mount_info->source)) {
             continue;
         }
@@ -123,7 +123,7 @@ HashMap<int, int> TreeNode::populate_filesize_tree(Vector<MountInfo>& mounts, Fu
                 } else {
                     auto st = st_or_error.release_value();
                     if (S_ISDIR(st.st_mode)) {
-                        queue.enqueue(QueueEntry(builder.to_deprecated_string(), &child));
+                        queue.enqueue(QueueEntry(builder.to_byte_string(), &child));
                     } else {
                         child.m_area = st.st_size;
                     }
@@ -137,7 +137,7 @@ HashMap<int, int> TreeNode::populate_filesize_tree(Vector<MountInfo>& mounts, Fu
     return error_accumulator;
 }
 
-Optional<TreeNode const&> TreeNode::child_with_name(DeprecatedString name) const
+Optional<TreeNode const&> TreeNode::child_with_name(ByteString name) const
 {
     for (auto& child : *m_children) {
         if (child.name() == name)
diff --git a/Userland/Applications/SpaceAnalyzer/Tree.h b/Userland/Applications/SpaceAnalyzer/Tree.h
index 663f2614342..34e0913a782 100644
--- a/Userland/Applications/SpaceAnalyzer/Tree.h
+++ b/Userland/Applications/SpaceAnalyzer/Tree.h
@@ -6,22 +6,22 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/OwnPtr.h>
 #include <AK/Vector.h>
 
 struct MountInfo {
-    DeprecatedString mount_point;
-    DeprecatedString source;
+    ByteString mount_point;
+    ByteString source;
 };
 
 class TreeNode final {
 public:
-    TreeNode(DeprecatedString name)
+    TreeNode(ByteString name)
         : m_name(move(name)) {};
 
-    DeprecatedString name() const { return m_name; }
+    ByteString name() const { return m_name; }
     i64 area() const { return m_area; }
     size_t num_children() const
     {
@@ -31,21 +31,21 @@ public:
         return 0;
     }
     TreeNode const& child_at(size_t i) const { return m_children->at(i); }
-    Optional<TreeNode const&> child_with_name(DeprecatedString name) const;
+    Optional<TreeNode const&> child_with_name(ByteString name) const;
     void sort_children_by_area() const;
     HashMap<int, int> populate_filesize_tree(Vector<MountInfo>& mounts, Function<void(size_t)> on_progress);
 
 private:
     long long int update_totals();
 
-    DeprecatedString m_name;
+    ByteString m_name;
     i64 m_area { 0 };
     OwnPtr<Vector<TreeNode>> m_children;
 };
 
 class Tree {
 public:
-    static ErrorOr<NonnullOwnPtr<Tree>> create(DeprecatedString root_name)
+    static ErrorOr<NonnullOwnPtr<Tree>> create(ByteString root_name)
     {
         return adopt_nonnull_own_or_enomem(new (nothrow) Tree(move(root_name)));
     }
@@ -57,7 +57,7 @@ public:
     }
 
 private:
-    Tree(DeprecatedString root_name)
+    Tree(ByteString root_name)
         : m_root(move(root_name)) {};
     TreeNode m_root;
 };
diff --git a/Userland/Applications/SpaceAnalyzer/TreeMapWidget.cpp b/Userland/Applications/SpaceAnalyzer/TreeMapWidget.cpp
index cf9f632d416..3679d2ba6af 100644
--- a/Userland/Applications/SpaceAnalyzer/TreeMapWidget.cpp
+++ b/Userland/Applications/SpaceAnalyzer/TreeMapWidget.cpp
@@ -9,7 +9,7 @@
 #include "ProgressWindow.h"
 #include "Tree.h"
 #include <AK/Array.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NumberFormat.h>
 #include <LibGUI/ConnectionToWindowServer.h>
 #include <LibGUI/Painter.h>
@@ -97,7 +97,7 @@ void TreeMapWidget::paint_cell_frame(GUI::Painter& painter, TreeNode const& node
             text_rect.take_from_top(font().presentation_size() + 1);
             painter.draw_text(text_rect, human_readable_size(node.area()), font(), Gfx::TextAlignment::TopLeft, Color::Black);
         } else {
-            painter.draw_text(text_rect, DeprecatedString::formatted("{} - {}", node.name(), human_readable_size(node.area())), font(), Gfx::TextAlignment::TopLeft, Color::Black);
+            painter.draw_text(text_rect, ByteString::formatted("{} - {}", node.name(), human_readable_size(node.area())), font(), Gfx::TextAlignment::TopLeft, Color::Black);
         }
         painter.clear_clip_rect();
     }
@@ -261,13 +261,13 @@ void TreeMapWidget::paint_event(GUI::PaintEvent& event)
     }
 }
 
-Vector<DeprecatedString> TreeMapWidget::path_to_position(Gfx::IntPoint position)
+Vector<ByteString> TreeMapWidget::path_to_position(Gfx::IntPoint position)
 {
     TreeNode const* node = path_node(m_viewpoint);
     if (!node) {
         return {};
     }
-    Vector<DeprecatedString> path;
+    Vector<ByteString> path;
     lay_out_children(*node, frame_inner_rect(), m_viewpoint, [&](TreeNode const& node, int, Gfx::IntRect const& rect, Gfx::IntRect const&, int, HasLabel, IsRemainder is_remainder) {
         if (is_remainder == IsRemainder::No && rect.contains(position)) {
             path.append(node.name());
@@ -381,8 +381,8 @@ static ErrorOr<void> fill_mounts(Vector<MountInfo>& output)
     TRY(json.as_array().try_for_each([&output](JsonValue const& value) -> ErrorOr<void> {
         auto& filesystem_object = value.as_object();
         MountInfo mount_info;
-        mount_info.mount_point = filesystem_object.get_deprecated_string("mount_point"sv).value_or({});
-        mount_info.source = filesystem_object.get_deprecated_string("source"sv).value_or("none");
+        mount_info.mount_point = filesystem_object.get_byte_string("mount_point"sv).value_or({});
+        mount_info.source = filesystem_object.get_byte_string("source"sv).value_or("none");
         TRY(output.try_append(mount_info));
         return {};
     }));
@@ -420,7 +420,7 @@ ErrorOr<void> TreeMapWidget::analyze(GUI::Statusbar& statusbar)
             builder.append({ error, strlen(error) });
             builder.append(" ("sv);
             int value = errors.get(key).value();
-            builder.append(DeprecatedString::number(value));
+            builder.append(ByteString::number(value));
             if (value == 1) {
                 builder.append(" time"sv);
             } else {
diff --git a/Userland/Applications/SpaceAnalyzer/TreeMapWidget.h b/Userland/Applications/SpaceAnalyzer/TreeMapWidget.h
index bfed7cfe855..6131e839264 100644
--- a/Userland/Applications/SpaceAnalyzer/TreeMapWidget.h
+++ b/Userland/Applications/SpaceAnalyzer/TreeMapWidget.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include "Tree.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibGUI/Frame.h>
 #include <LibGfx/Rect.h>
 
@@ -50,11 +50,11 @@ private:
     template<typename Function>
     void lay_out_children(TreeNode const&, Gfx::IntRect const&, int depth, Function);
     void paint_cell_frame(GUI::Painter&, TreeNode const&, Gfx::IntRect const&, Gfx::IntRect const&, int depth, HasLabel has_label) const;
-    Vector<DeprecatedString> path_to_position(Gfx::IntPoint);
+    Vector<ByteString> path_to_position(Gfx::IntPoint);
     void recalculate_path_for_new_tree();
 
     OwnPtr<Tree> m_tree;
-    Vector<DeprecatedString> m_path_segments;
+    Vector<ByteString> m_path_segments;
     size_t m_viewpoint { 0 }; // Current position within m_path_segments.
     void const* m_selected_node_cache;
 };
diff --git a/Userland/Applications/SpaceAnalyzer/main.cpp b/Userland/Applications/SpaceAnalyzer/main.cpp
index abc94565a32..4959e5be30c 100644
--- a/Userland/Applications/SpaceAnalyzer/main.cpp
+++ b/Userland/Applications/SpaceAnalyzer/main.cpp
@@ -28,7 +28,7 @@
 
 static auto const APP_NAME = "Space Analyzer"_string;
 
-static DeprecatedString get_absolute_path_to_selected_node(SpaceAnalyzer::TreeMapWidget const& tree_map_widget, bool include_last_node = true)
+static ByteString get_absolute_path_to_selected_node(SpaceAnalyzer::TreeMapWidget const& tree_map_widget, bool include_last_node = true)
 {
     StringBuilder path_builder;
     for (size_t k = 0; k < tree_map_widget.path_size() - (include_last_node ? 0 : 1); k++) {
@@ -38,7 +38,7 @@ static DeprecatedString get_absolute_path_to_selected_node(SpaceAnalyzer::TreeMa
         TreeNode const* node = tree_map_widget.path_node(k);
         path_builder.append(node->name());
     }
-    return path_builder.to_deprecated_string();
+    return path_builder.to_byte_string();
 }
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
@@ -72,7 +72,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     file_menu->add_action(GUI::Action::create("&Analyze", { KeyCode::Key_F5 }, TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/reload.png"sv)), [&](auto&) {
         // FIXME: Just modify the tree in memory instead of traversing the entire file system
         if (auto result = tree_map_widget.analyze(statusbar); result.is_error()) {
-            GUI::MessageBox::show_error(window, DeprecatedString::formatted("{}", result.error()));
+            GUI::MessageBox::show_error(window, ByteString::formatted("{}", result.error()));
         }
     }));
     file_menu->add_separator();
@@ -104,7 +104,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         GUI::Clipboard::the().set_plain_text(get_absolute_path_to_selected_node(tree_map_widget));
     });
     auto delete_action = GUI::CommonActions::make_delete_action([&](auto&) {
-        DeprecatedString selected_node_path = get_absolute_path_to_selected_node(tree_map_widget);
+        ByteString selected_node_path = get_absolute_path_to_selected_node(tree_map_widget);
         bool try_again = true;
         while (try_again) {
             try_again = false;
@@ -112,7 +112,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             auto deletion_result = FileSystem::remove(selected_node_path, FileSystem::RecursionMode::Allowed);
             if (deletion_result.is_error()) {
                 auto retry_message_result = GUI::MessageBox::show(window,
-                    DeprecatedString::formatted("Failed to delete \"{}\": {}. Retry?",
+                    ByteString::formatted("Failed to delete \"{}\": {}. Retry?",
                         selected_node_path,
                         deletion_result.error()),
                     "Deletion failed"sv,
@@ -123,7 +123,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 }
             } else {
                 GUI::MessageBox::show(window,
-                    DeprecatedString::formatted("Successfully deleted \"{}\".", selected_node_path),
+                    ByteString::formatted("Successfully deleted \"{}\".", selected_node_path),
                     "Deletion completed"sv,
                     GUI::MessageBox::Type::Information,
                     GUI::MessageBox::InputType::OK);
@@ -131,7 +131,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         }
 
         if (auto result = tree_map_widget.analyze(statusbar); result.is_error()) {
-            GUI::MessageBox::show_error(window, DeprecatedString::formatted("{}", result.error()));
+            GUI::MessageBox::show_error(window, ByteString::formatted("{}", result.error()));
         }
     });
 
@@ -165,14 +165,14 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
             // Sneakily set the window title here, while the StringBuilder holds the right amount of the path.
             if (k == tree_map_widget.viewpoint())
-                window->set_title(DeprecatedString::formatted("{} - SpaceAnalyzer", builder.string_view()));
+                window->set_title(ByteString::formatted("{} - SpaceAnalyzer", builder.string_view()));
 
             breadcrumbbar.append_segment(node->name(), GUI::FileIconProvider::icon_for_path(builder.string_view()).bitmap_for_size(16), builder.string_view(), MUST(builder.to_string()));
         }
         breadcrumbbar.set_selected_segment(tree_map_widget.viewpoint());
     };
     tree_map_widget.on_context_menu_request = [&](const GUI::ContextMenuEvent& event) {
-        DeprecatedString selected_node_path = get_absolute_path_to_selected_node(tree_map_widget);
+        ByteString selected_node_path = get_absolute_path_to_selected_node(tree_map_widget);
         if (selected_node_path.is_empty())
             return;
         delete_action->set_enabled(FileSystem::can_delete_or_move(selected_node_path));
diff --git a/Userland/Applications/Spreadsheet/Cell.cpp b/Userland/Applications/Spreadsheet/Cell.cpp
index ea630d9e90d..d54ad3175b7 100644
--- a/Userland/Applications/Spreadsheet/Cell.cpp
+++ b/Userland/Applications/Spreadsheet/Cell.cpp
@@ -12,7 +12,7 @@
 
 namespace Spreadsheet {
 
-void Cell::set_data(DeprecatedString new_data)
+void Cell::set_data(ByteString new_data)
 {
     // If we are a formula, we do not save the beginning '=', if the new_data is "" we can simply change our kind
     if (m_kind == Formula && m_data.is_empty() && new_data.is_empty()) {
@@ -43,7 +43,7 @@ void Cell::set_data(JS::Value new_data)
     StringBuilder builder;
 
     builder.append(new_data.to_string_without_side_effects());
-    m_data = builder.to_deprecated_string();
+    m_data = builder.to_byte_string();
 
     m_evaluated_data = move(new_data);
 }
@@ -86,7 +86,7 @@ CellType const& Cell::type() const
     return *CellType::get_by_name("Identity"sv);
 }
 
-JS::ThrowCompletionOr<DeprecatedString> Cell::typed_display() const
+JS::ThrowCompletionOr<ByteString> Cell::typed_display() const
 {
     return type().display(const_cast<Cell&>(*this), m_type_metadata);
 }
@@ -163,13 +163,13 @@ JS::Value Cell::js_data()
     return JS::PrimitiveString::create(vm, m_data);
 }
 
-DeprecatedString Cell::source() const
+ByteString Cell::source() const
 {
     StringBuilder builder;
     if (m_kind == Formula)
         builder.append('=');
     builder.append(m_data);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // FIXME: Find a better way to figure out dependencies
diff --git a/Userland/Applications/Spreadsheet/Cell.h b/Userland/Applications/Spreadsheet/Cell.h
index 34456f09a73..d7072f59529 100644
--- a/Userland/Applications/Spreadsheet/Cell.h
+++ b/Userland/Applications/Spreadsheet/Cell.h
@@ -11,7 +11,7 @@
 #include "Forward.h"
 #include "JSIntegration.h"
 #include "Position.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Types.h>
 #include <AK/WeakPtr.h>
 #include <LibGUI/Command.h>
@@ -24,7 +24,7 @@ struct Cell : public Weakable<Cell> {
         Formula,
     };
 
-    Cell(DeprecatedString data, Position position, WeakPtr<Sheet> sheet)
+    Cell(ByteString data, Position position, WeakPtr<Sheet> sheet)
         : m_dirty(false)
         , m_data(move(data))
         , m_kind(LiteralString)
@@ -33,7 +33,7 @@ struct Cell : public Weakable<Cell> {
     {
     }
 
-    Cell(DeprecatedString source, JS::Value&& cell_value, Position position, WeakPtr<Sheet> sheet)
+    Cell(ByteString source, JS::Value&& cell_value, Position position, WeakPtr<Sheet> sheet)
         : m_dirty(false)
         , m_data(move(source))
         , m_evaluated_data(move(cell_value))
@@ -45,7 +45,7 @@ struct Cell : public Weakable<Cell> {
 
     void reference_from(Cell*);
 
-    void set_data(DeprecatedString new_data);
+    void set_data(ByteString new_data);
     void set_data(JS::Value new_data);
     bool dirty() const { return m_dirty; }
     void clear_dirty() { m_dirty = false; }
@@ -55,7 +55,7 @@ struct Cell : public Weakable<Cell> {
         if (!m_name_for_javascript.is_empty())
             return m_name_for_javascript;
 
-        m_name_for_javascript = DeprecatedString::formatted("cell {}", m_position.to_cell_identifier(sheet));
+        m_name_for_javascript = ByteString::formatted("cell {}", m_position.to_cell_identifier(sheet));
         return m_name_for_javascript;
     }
 
@@ -67,7 +67,7 @@ struct Cell : public Weakable<Cell> {
         return m_thrown_value;
     }
 
-    DeprecatedString const& data() const { return m_data; }
+    ByteString const& data() const { return m_data; }
     const JS::Value& evaluated_data() const { return m_evaluated_data; }
     Kind kind() const { return m_kind; }
     Vector<WeakPtr<Cell>> const& referencing_cells() const { return m_referencing_cells; }
@@ -95,14 +95,14 @@ struct Cell : public Weakable<Cell> {
         m_conditional_formats = move(fmts);
     }
 
-    JS::ThrowCompletionOr<DeprecatedString> typed_display() const;
+    JS::ThrowCompletionOr<ByteString> typed_display() const;
     JS::ThrowCompletionOr<JS::Value> typed_js_data() const;
 
     CellType const& type() const;
     CellTypeMetadata const& type_metadata() const { return m_type_metadata; }
     CellTypeMetadata& type_metadata() { return m_type_metadata; }
 
-    DeprecatedString source() const;
+    ByteString source() const;
 
     JS::Value js_data();
 
@@ -117,7 +117,7 @@ struct Cell : public Weakable<Cell> {
 private:
     bool m_dirty { false };
     bool m_evaluated_externally { false };
-    DeprecatedString m_data;
+    ByteString m_data;
     JS::Value m_evaluated_data;
     JS::Value m_thrown_value;
     Kind m_kind { LiteralString };
@@ -126,7 +126,7 @@ private:
     CellType const* m_type { nullptr };
     CellTypeMetadata m_type_metadata;
     Position m_position;
-    mutable DeprecatedString m_name_for_javascript;
+    mutable ByteString m_name_for_javascript;
 
     Vector<ConditionalFormat> m_conditional_formats;
     Format m_evaluated_formats;
diff --git a/Userland/Applications/Spreadsheet/CellType/Date.cpp b/Userland/Applications/Spreadsheet/CellType/Date.cpp
index 085acaf46d5..d74898db339 100644
--- a/Userland/Applications/Spreadsheet/CellType/Date.cpp
+++ b/Userland/Applications/Spreadsheet/CellType/Date.cpp
@@ -17,12 +17,12 @@ DateCell::DateCell()
 {
 }
 
-JS::ThrowCompletionOr<DeprecatedString> DateCell::display(Cell& cell, CellTypeMetadata const& metadata) const
+JS::ThrowCompletionOr<ByteString> DateCell::display(Cell& cell, CellTypeMetadata const& metadata) const
 {
-    return propagate_failure(cell, [&]() -> JS::ThrowCompletionOr<DeprecatedString> {
+    return propagate_failure(cell, [&]() -> JS::ThrowCompletionOr<ByteString> {
         auto& vm = cell.sheet().global_object().vm();
         auto timestamp = TRY(js_value(cell, metadata));
-        auto string = Core::DateTime::from_timestamp(TRY(timestamp.to_i32(vm))).to_deprecated_string(metadata.format.is_empty() ? "%Y-%m-%d %H:%M:%S"sv : metadata.format.view());
+        auto string = Core::DateTime::from_timestamp(TRY(timestamp.to_i32(vm))).to_byte_string(metadata.format.is_empty() ? "%Y-%m-%d %H:%M:%S"sv : metadata.format.view());
 
         if (metadata.length >= 0)
             return string.substring(0, metadata.length);
diff --git a/Userland/Applications/Spreadsheet/CellType/Date.h b/Userland/Applications/Spreadsheet/CellType/Date.h
index 61258e4eb63..72ab9888238 100644
--- a/Userland/Applications/Spreadsheet/CellType/Date.h
+++ b/Userland/Applications/Spreadsheet/CellType/Date.h
@@ -16,7 +16,7 @@ class DateCell : public CellType {
 public:
     DateCell();
     virtual ~DateCell() override = default;
-    virtual JS::ThrowCompletionOr<DeprecatedString> display(Cell&, CellTypeMetadata const&) const override;
+    virtual JS::ThrowCompletionOr<ByteString> display(Cell&, CellTypeMetadata const&) const override;
     virtual JS::ThrowCompletionOr<JS::Value> js_value(Cell&, CellTypeMetadata const&) const override;
     virtual String metadata_hint(MetadataName) const override;
 };
diff --git a/Userland/Applications/Spreadsheet/CellType/Format.cpp b/Userland/Applications/Spreadsheet/CellType/Format.cpp
index 663aa2173de..431254d6f5f 100644
--- a/Userland/Applications/Spreadsheet/CellType/Format.cpp
+++ b/Userland/Applications/Spreadsheet/CellType/Format.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "Format.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/PrintfImplementation.h>
 #include <AK/StringBuilder.h>
 
@@ -37,13 +37,13 @@ struct PrintfImpl : public PrintfImplementation::PrintfImpl<PutChFunc, ArgumentL
     }
 };
 
-DeprecatedString format_double(char const* format, double value)
+ByteString format_double(char const* format, double value)
 {
     StringBuilder builder;
     auto putch = [&](auto, auto ch) { builder.append(ch); };
     printf_internal<decltype(putch), PrintfImpl, double, SingleEntryListNext>(putch, nullptr, format, value);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/Userland/Applications/Spreadsheet/CellType/Format.h b/Userland/Applications/Spreadsheet/CellType/Format.h
index 1429692e008..b9776a27e04 100644
--- a/Userland/Applications/Spreadsheet/CellType/Format.h
+++ b/Userland/Applications/Spreadsheet/CellType/Format.h
@@ -10,6 +10,6 @@
 
 namespace Spreadsheet {
 
-DeprecatedString format_double(char const* format, double value);
+ByteString format_double(char const* format, double value);
 
 }
diff --git a/Userland/Applications/Spreadsheet/CellType/Identity.cpp b/Userland/Applications/Spreadsheet/CellType/Identity.cpp
index 203c0401208..1d7c9820525 100644
--- a/Userland/Applications/Spreadsheet/CellType/Identity.cpp
+++ b/Userland/Applications/Spreadsheet/CellType/Identity.cpp
@@ -15,14 +15,14 @@ IdentityCell::IdentityCell()
 {
 }
 
-JS::ThrowCompletionOr<DeprecatedString> IdentityCell::display(Cell& cell, CellTypeMetadata const& metadata) const
+JS::ThrowCompletionOr<ByteString> IdentityCell::display(Cell& cell, CellTypeMetadata const& metadata) const
 {
     auto& vm = cell.sheet().global_object().vm();
     auto data = cell.js_data();
     if (!metadata.format.is_empty())
         data = TRY(cell.sheet().evaluate(metadata.format, &cell));
 
-    return data.to_deprecated_string(vm);
+    return data.to_byte_string(vm);
 }
 
 JS::ThrowCompletionOr<JS::Value> IdentityCell::js_value(Cell& cell, CellTypeMetadata const&) const
diff --git a/Userland/Applications/Spreadsheet/CellType/Identity.h b/Userland/Applications/Spreadsheet/CellType/Identity.h
index a3c7dbe9a34..fcfd3707c46 100644
--- a/Userland/Applications/Spreadsheet/CellType/Identity.h
+++ b/Userland/Applications/Spreadsheet/CellType/Identity.h
@@ -15,7 +15,7 @@ class IdentityCell : public CellType {
 public:
     IdentityCell();
     virtual ~IdentityCell() override = default;
-    virtual JS::ThrowCompletionOr<DeprecatedString> display(Cell&, CellTypeMetadata const&) const override;
+    virtual JS::ThrowCompletionOr<ByteString> display(Cell&, CellTypeMetadata const&) const override;
     virtual JS::ThrowCompletionOr<JS::Value> js_value(Cell&, CellTypeMetadata const&) const override;
     virtual String metadata_hint(MetadataName) const override;
 };
diff --git a/Userland/Applications/Spreadsheet/CellType/Numeric.cpp b/Userland/Applications/Spreadsheet/CellType/Numeric.cpp
index 92bbe1971e9..ed85b9c8604 100644
--- a/Userland/Applications/Spreadsheet/CellType/Numeric.cpp
+++ b/Userland/Applications/Spreadsheet/CellType/Numeric.cpp
@@ -18,14 +18,14 @@ NumericCell::NumericCell()
 {
 }
 
-JS::ThrowCompletionOr<DeprecatedString> NumericCell::display(Cell& cell, CellTypeMetadata const& metadata) const
+JS::ThrowCompletionOr<ByteString> NumericCell::display(Cell& cell, CellTypeMetadata const& metadata) const
 {
-    return propagate_failure(cell, [&]() -> JS::ThrowCompletionOr<DeprecatedString> {
+    return propagate_failure(cell, [&]() -> JS::ThrowCompletionOr<ByteString> {
         auto& vm = cell.sheet().global_object().vm();
         auto value = TRY(js_value(cell, metadata));
-        DeprecatedString string;
+        ByteString string;
         if (metadata.format.is_empty())
-            string = TRY(value.to_deprecated_string(vm));
+            string = TRY(value.to_byte_string(vm));
         else
             string = format_double(metadata.format.characters(), TRY(value.to_double(vm)));
 
diff --git a/Userland/Applications/Spreadsheet/CellType/Numeric.h b/Userland/Applications/Spreadsheet/CellType/Numeric.h
index 4a6672c8162..c8480ea9d5c 100644
--- a/Userland/Applications/Spreadsheet/CellType/Numeric.h
+++ b/Userland/Applications/Spreadsheet/CellType/Numeric.h
@@ -26,7 +26,7 @@ class NumericCell : public CellType {
 public:
     NumericCell();
     virtual ~NumericCell() override = default;
-    virtual JS::ThrowCompletionOr<DeprecatedString> display(Cell&, CellTypeMetadata const&) const override;
+    virtual JS::ThrowCompletionOr<ByteString> display(Cell&, CellTypeMetadata const&) const override;
     virtual JS::ThrowCompletionOr<JS::Value> js_value(Cell&, CellTypeMetadata const&) const override;
     virtual String metadata_hint(MetadataName) const override;
 };
diff --git a/Userland/Applications/Spreadsheet/CellType/String.cpp b/Userland/Applications/Spreadsheet/CellType/String.cpp
index 379ac5215cb..c0a9ff67bf4 100644
--- a/Userland/Applications/Spreadsheet/CellType/String.cpp
+++ b/Userland/Applications/Spreadsheet/CellType/String.cpp
@@ -15,10 +15,10 @@ StringCell::StringCell()
 {
 }
 
-JS::ThrowCompletionOr<DeprecatedString> StringCell::display(Cell& cell, CellTypeMetadata const& metadata) const
+JS::ThrowCompletionOr<ByteString> StringCell::display(Cell& cell, CellTypeMetadata const& metadata) const
 {
     auto& vm = cell.sheet().global_object().vm();
-    auto string = TRY(cell.js_data().to_deprecated_string(vm));
+    auto string = TRY(cell.js_data().to_byte_string(vm));
     if (metadata.length >= 0)
         return string.substring(0, metadata.length);
 
diff --git a/Userland/Applications/Spreadsheet/CellType/String.h b/Userland/Applications/Spreadsheet/CellType/String.h
index 28b145c4478..7512207b431 100644
--- a/Userland/Applications/Spreadsheet/CellType/String.h
+++ b/Userland/Applications/Spreadsheet/CellType/String.h
@@ -15,7 +15,7 @@ class StringCell : public CellType {
 public:
     StringCell();
     virtual ~StringCell() override = default;
-    virtual JS::ThrowCompletionOr<DeprecatedString> display(Cell&, CellTypeMetadata const&) const override;
+    virtual JS::ThrowCompletionOr<ByteString> display(Cell&, CellTypeMetadata const&) const override;
     virtual JS::ThrowCompletionOr<JS::Value> js_value(Cell&, CellTypeMetadata const&) const override;
     virtual String metadata_hint(MetadataName) const override;
 };
diff --git a/Userland/Applications/Spreadsheet/CellType/Type.cpp b/Userland/Applications/Spreadsheet/CellType/Type.cpp
index 259cf9f001d..903b0bb3046 100644
--- a/Userland/Applications/Spreadsheet/CellType/Type.cpp
+++ b/Userland/Applications/Spreadsheet/CellType/Type.cpp
@@ -12,7 +12,7 @@
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 
-static HashMap<DeprecatedString, Spreadsheet::CellType*> s_cell_types;
+static HashMap<ByteString, Spreadsheet::CellType*> s_cell_types;
 static Spreadsheet::StringCell s_string_cell;
 static Spreadsheet::NumericCell s_numeric_cell;
 static Spreadsheet::IdentityCell s_identity_cell;
diff --git a/Userland/Applications/Spreadsheet/CellType/Type.h b/Userland/Applications/Spreadsheet/CellType/Type.h
index 5badeae308f..deefb6f9d89 100644
--- a/Userland/Applications/Spreadsheet/CellType/Type.h
+++ b/Userland/Applications/Spreadsheet/CellType/Type.h
@@ -8,7 +8,7 @@
 
 #include "../ConditionalFormatting.h"
 #include "../Forward.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <LibGfx/Color.h>
 #include <LibGfx/TextAlignment.h>
@@ -18,7 +18,7 @@ namespace Spreadsheet {
 
 struct CellTypeMetadata {
     int length { -1 };
-    DeprecatedString format;
+    ByteString format;
     Gfx::TextAlignment alignment { Gfx::TextAlignment::CenterRight };
     Format static_format;
 };
@@ -35,18 +35,18 @@ public:
     static CellType const* get_by_name(StringView);
     static Vector<StringView> names();
 
-    virtual JS::ThrowCompletionOr<DeprecatedString> display(Cell&, CellTypeMetadata const&) const = 0;
+    virtual JS::ThrowCompletionOr<ByteString> display(Cell&, CellTypeMetadata const&) const = 0;
     virtual JS::ThrowCompletionOr<JS::Value> js_value(Cell&, CellTypeMetadata const&) const = 0;
     virtual String metadata_hint(MetadataName) const { return {}; }
     virtual ~CellType() = default;
 
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
 
 protected:
     CellType(StringView name);
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
 };
 
 }
diff --git a/Userland/Applications/Spreadsheet/CellTypeDialog.cpp b/Userland/Applications/Spreadsheet/CellTypeDialog.cpp
index 3027f00addd..1ce5344ecd4 100644
--- a/Userland/Applications/Spreadsheet/CellTypeDialog.cpp
+++ b/Userland/Applications/Spreadsheet/CellTypeDialog.cpp
@@ -61,9 +61,9 @@ CellTypeDialog::CellTypeDialog(Vector<Position> const& positions, Sheet& sheet,
     ok_button.on_click = [&](auto) { done(ExecResult::OK); };
 }
 
-Vector<DeprecatedString> const g_horizontal_alignments { "Left", "Center", "Right" };
-Vector<DeprecatedString> const g_vertical_alignments { "Top", "Center", "Bottom" };
-Vector<DeprecatedString> g_types;
+Vector<ByteString> const g_horizontal_alignments { "Left", "Center", "Right" };
+Vector<ByteString> const g_vertical_alignments { "Top", "Center", "Bottom" };
+Vector<ByteString> g_types;
 
 constexpr static CellTypeDialog::VerticalAlignment vertical_alignment_from(Gfx::TextAlignment alignment)
 {
@@ -142,7 +142,7 @@ void CellTypeDialog::setup_tabs(GUI::TabWidget& tabs, Vector<Position> const& po
         right_side.set_fixed_width(170);
 
         auto& type_list = left_side.add<GUI::ListView>();
-        type_list.set_model(*GUI::ItemListModel<DeprecatedString>::create(g_types));
+        type_list.set_model(*GUI::ItemListModel<ByteString>::create(g_types));
         type_list.set_should_hide_unnecessary_scrollbars(true);
         type_list.on_selection_change = [&] {
             const auto& index = type_list.selection().first();
@@ -188,7 +188,7 @@ void CellTypeDialog::setup_tabs(GUI::TabWidget& tabs, Vector<Position> const& po
             checkbox.on_checked = [&](auto checked) {
                 editor.set_enabled(checked);
                 if (!checked)
-                    m_format = DeprecatedString::empty();
+                    m_format = ByteString::empty();
                 editor.set_text(m_format);
             };
             editor.on_change = [&] {
@@ -213,7 +213,7 @@ void CellTypeDialog::setup_tabs(GUI::TabWidget& tabs, Vector<Position> const& po
 
             auto& horizontal_combobox = alignment_tab.add<GUI::ComboBox>();
             horizontal_combobox.set_only_allow_values_from_model(true);
-            horizontal_combobox.set_model(*GUI::ItemListModel<DeprecatedString>::create(g_horizontal_alignments));
+            horizontal_combobox.set_model(*GUI::ItemListModel<ByteString>::create(g_horizontal_alignments));
             horizontal_combobox.set_selected_index((int)m_horizontal_alignment);
             horizontal_combobox.on_change = [&](auto&, const GUI::ModelIndex& index) {
                 switch (index.row()) {
@@ -244,7 +244,7 @@ void CellTypeDialog::setup_tabs(GUI::TabWidget& tabs, Vector<Position> const& po
 
             auto& vertical_combobox = alignment_tab.add<GUI::ComboBox>();
             vertical_combobox.set_only_allow_values_from_model(true);
-            vertical_combobox.set_model(*GUI::ItemListModel<DeprecatedString>::create(g_vertical_alignments));
+            vertical_combobox.set_model(*GUI::ItemListModel<ByteString>::create(g_vertical_alignments));
             vertical_combobox.set_selected_index((int)m_vertical_alignment);
             vertical_combobox.on_change = [&](auto&, const GUI::ModelIndex& index) {
                 switch (index.row()) {
diff --git a/Userland/Applications/Spreadsheet/CellTypeDialog.h b/Userland/Applications/Spreadsheet/CellTypeDialog.h
index 9171e27e9c4..8060924485a 100644
--- a/Userland/Applications/Spreadsheet/CellTypeDialog.h
+++ b/Userland/Applications/Spreadsheet/CellTypeDialog.h
@@ -39,7 +39,7 @@ private:
     CellType const* m_type { nullptr };
 
     int m_length { -1 };
-    DeprecatedString m_format;
+    ByteString m_format;
     HorizontalAlignment m_horizontal_alignment { HorizontalAlignment::Right };
     VerticalAlignment m_vertical_alignment { VerticalAlignment::Center };
     Format m_static_format;
diff --git a/Userland/Applications/Spreadsheet/ConditionalFormatting.h b/Userland/Applications/Spreadsheet/ConditionalFormatting.h
index d6e324d91dc..02ae9cd8554 100644
--- a/Userland/Applications/Spreadsheet/ConditionalFormatting.h
+++ b/Userland/Applications/Spreadsheet/ConditionalFormatting.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include "Forward.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibGUI/AbstractScrollableWidget.h>
 #include <LibGfx/Color.h>
 
@@ -19,7 +19,7 @@ struct Format {
 };
 
 struct ConditionalFormat : public Format {
-    DeprecatedString condition;
+    ByteString condition;
 };
 
 enum class FormatType {
diff --git a/Userland/Applications/Spreadsheet/ExportDialog.cpp b/Userland/Applications/Spreadsheet/ExportDialog.cpp
index cc84d1618e1..66f566078b9 100644
--- a/Userland/Applications/Spreadsheet/ExportDialog.cpp
+++ b/Userland/Applications/Spreadsheet/ExportDialog.cpp
@@ -7,7 +7,7 @@
 #include "ExportDialog.h"
 #include "Spreadsheet.h"
 #include "Workbook.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/JsonArray.h>
 #include <AK/LexicalPath.h>
 #include <AK/MemoryStream.h>
@@ -59,7 +59,7 @@ CSVExportDialogPage::CSVExportDialogPage(Sheet const& sheet)
 
     m_data_preview_text_editor->set_should_hide_unnecessary_scrollbars(true);
 
-    m_quote_escape_combo_box->set_model(GUI::ItemListModel<DeprecatedString>::create(m_quote_escape_items));
+    m_quote_escape_combo_box->set_model(GUI::ItemListModel<ByteString>::create(m_quote_escape_items));
 
     // By default, use commas, double quotes with repeat, disable headers, and quote only the fields that require quoting.
     m_delimiter_comma_radio->set_checked(true);
@@ -91,7 +91,7 @@ CSVExportDialogPage::CSVExportDialogPage(Sheet const& sheet)
 
 auto CSVExportDialogPage::generate(Stream& stream, GenerationType type) -> ErrorOr<void>
 {
-    auto delimiter = TRY([this]() -> ErrorOr<DeprecatedString> {
+    auto delimiter = TRY([this]() -> ErrorOr<ByteString> {
         if (m_delimiter_other_radio->is_checked()) {
             if (m_delimiter_other_text_box->text().is_empty())
                 return Error::from_string_literal("Delimiter unset");
@@ -108,7 +108,7 @@ auto CSVExportDialogPage::generate(Stream& stream, GenerationType type) -> Error
         return Error::from_string_literal("Delimiter unset");
     }());
 
-    auto quote = TRY([this]() -> ErrorOr<DeprecatedString> {
+    auto quote = TRY([this]() -> ErrorOr<ByteString> {
         if (m_quote_other_radio->is_checked()) {
             if (m_quote_other_text_box->text().is_empty())
                 return Error::from_string_literal("Quote separator unset");
@@ -140,7 +140,7 @@ auto CSVExportDialogPage::generate(Stream& stream, GenerationType type) -> Error
     };
 
     auto behaviors = Writer::default_behaviors();
-    Vector<DeprecatedString> empty_headers;
+    Vector<ByteString> empty_headers;
     auto* headers = &empty_headers;
 
     if (should_export_headers) {
@@ -153,7 +153,7 @@ auto CSVExportDialogPage::generate(Stream& stream, GenerationType type) -> Error
 
     switch (type) {
     case GenerationType::Normal:
-        TRY((Writer::XSV<decltype(m_data), Vector<DeprecatedString>>::generate(stream, m_data, move(traits), *headers, behaviors)));
+        TRY((Writer::XSV<decltype(m_data), Vector<ByteString>>::generate(stream, m_data, move(traits), *headers, behaviors)));
         break;
     case GenerationType::Preview:
         TRY((Writer::XSV<decltype(m_data), decltype(*headers)>::generate_preview(stream, m_data, move(traits), *headers, behaviors)));
@@ -176,10 +176,10 @@ void CSVExportDialogPage::update_preview()
         return {};
     }();
     if (maybe_error.is_error())
-        m_data_preview_text_editor->set_text(DeprecatedString::formatted("Cannot update preview: {}", maybe_error.error()));
+        m_data_preview_text_editor->set_text(ByteString::formatted("Cannot update preview: {}", maybe_error.error()));
 }
 
-ErrorOr<void> ExportDialog::make_and_run_for(StringView mime, Core::File& file, DeprecatedString filename, Workbook& workbook)
+ErrorOr<void> ExportDialog::make_and_run_for(StringView mime, Core::File& file, ByteString filename, Workbook& workbook)
 {
     auto wizard = TRY(GUI::WizardDialog::create(GUI::Application::the()->active_window()));
     wizard->set_title("File Export Wizard");
@@ -205,7 +205,7 @@ ErrorOr<void> ExportDialog::make_and_run_for(StringView mime, Core::File& file,
         for (auto& sheet : workbook.sheets())
             array.must_append(sheet->to_json());
 
-        auto file_content = array.to_deprecated_string();
+        auto file_content = array.to_byte_string();
         return file.write_until_depleted(file_content.bytes());
     };
 
@@ -223,11 +223,11 @@ ErrorOr<void> ExportDialog::make_and_run_for(StringView mime, Core::File& file,
         TRY(page->body_widget().load_from_gml(select_format_page_gml));
         auto format_combo_box = page->body_widget().find_descendant_of_type_named<GUI::ComboBox>("select_format_page_format_combo_box");
 
-        Vector<DeprecatedString> supported_formats {
+        Vector<ByteString> supported_formats {
             "CSV (text/csv)",
             "Spreadsheet Worksheet",
         };
-        format_combo_box->set_model(GUI::ItemListModel<DeprecatedString>::create(supported_formats));
+        format_combo_box->set_model(GUI::ItemListModel<ByteString>::create(supported_formats));
 
         wizard->push_page(page);
 
diff --git a/Userland/Applications/Spreadsheet/ExportDialog.h b/Userland/Applications/Spreadsheet/ExportDialog.h
index bdef59826b6..56424a8c69d 100644
--- a/Userland/Applications/Spreadsheet/ExportDialog.h
+++ b/Userland/Applications/Spreadsheet/ExportDialog.h
@@ -33,8 +33,8 @@ protected:
     void update_preview();
 
 private:
-    Vector<Vector<DeprecatedString>> m_data;
-    Vector<DeprecatedString> m_headers;
+    Vector<Vector<ByteString>> m_data;
+    Vector<ByteString> m_headers;
     RefPtr<GUI::WizardPage> m_page;
     RefPtr<GUI::RadioButton> m_delimiter_comma_radio;
     RefPtr<GUI::RadioButton> m_delimiter_semicolon_radio;
@@ -50,7 +50,7 @@ private:
     RefPtr<GUI::CheckBox> m_export_header_check_box;
     RefPtr<GUI::CheckBox> m_quote_all_fields_check_box;
     RefPtr<GUI::TextEditor> m_data_preview_text_editor;
-    Vector<DeprecatedString> m_quote_escape_items {
+    Vector<ByteString> m_quote_escape_items {
         // Note: Keep in sync with Writer::WriterTraits::QuoteEscape.
         "Repeat",
         "Backslash",
@@ -58,7 +58,7 @@ private:
 };
 
 struct ExportDialog {
-    static ErrorOr<void> make_and_run_for(StringView mime, Core::File&, DeprecatedString filename, Workbook&);
+    static ErrorOr<void> make_and_run_for(StringView mime, Core::File&, ByteString filename, Workbook&);
 };
 
 }
diff --git a/Userland/Applications/Spreadsheet/HelpWindow.cpp b/Userland/Applications/Spreadsheet/HelpWindow.cpp
index 04d5519d99f..833b3f7c402 100644
--- a/Userland/Applications/Spreadsheet/HelpWindow.cpp
+++ b/Userland/Applications/Spreadsheet/HelpWindow.cpp
@@ -38,7 +38,7 @@ public:
         return {};
     }
 
-    DeprecatedString key(const GUI::ModelIndex& index) const { return m_keys[index.row()]; }
+    ByteString key(const GUI::ModelIndex& index) const { return m_keys[index.row()]; }
 
     void set_from(JsonObject const& object)
     {
@@ -55,7 +55,7 @@ private:
     {
     }
 
-    Vector<DeprecatedString> m_keys;
+    Vector<ByteString> m_keys;
 };
 
 RefPtr<HelpWindow> HelpWindow::s_the { nullptr };
@@ -90,7 +90,7 @@ HelpWindow::HelpWindow(GUI::Window* parent)
             auto entry = LexicalPath::basename(example_path);
             auto doc_option = m_docs.get_object(entry);
             if (!doc_option.has_value()) {
-                GUI::MessageBox::show_error(this, DeprecatedString::formatted("No documentation entry found for '{}'", example_path));
+                GUI::MessageBox::show_error(this, ByteString::formatted("No documentation entry found for '{}'", example_path));
                 return;
             }
             auto& doc = doc_option.value();
@@ -98,13 +98,13 @@ HelpWindow::HelpWindow(GUI::Window* parent)
 
             auto maybe_example_data = doc.get_object("example_data"sv);
             if (!maybe_example_data.has_value()) {
-                GUI::MessageBox::show_error(this, DeprecatedString::formatted("No example data found for '{}'", example_path));
+                GUI::MessageBox::show_error(this, ByteString::formatted("No example data found for '{}'", example_path));
                 return;
             }
             auto& example_data = maybe_example_data.value();
 
             if (!example_data.has_object(name)) {
-                GUI::MessageBox::show_error(this, DeprecatedString::formatted("Example '{}' not found for '{}'", name, example_path));
+                GUI::MessageBox::show_error(this, ByteString::formatted("Example '{}' not found for '{}'", name, example_path));
                 return;
             }
             auto& value = example_data.get_object(name).value();
@@ -112,13 +112,13 @@ HelpWindow::HelpWindow(GUI::Window* parent)
             auto window = GUI::Window::construct(this);
             window->resize(size());
             window->set_icon(icon());
-            window->set_title(DeprecatedString::formatted("Spreadsheet Help - Example {} for {}", name, entry));
+            window->set_title(ByteString::formatted("Spreadsheet Help - Example {} for {}", name, entry));
             window->on_close = [window = window.ptr()] { window->remove_from_parent(); };
 
             auto widget = window->set_main_widget<SpreadsheetWidget>(window, Vector<NonnullRefPtr<Sheet>> {}, false);
             auto sheet = Sheet::from_json(value, widget->workbook());
             if (!sheet) {
-                GUI::MessageBox::show_error(this, DeprecatedString::formatted("Corrupted example '{}' in '{}'", name, example_path));
+                GUI::MessageBox::show_error(this, ByteString::formatted("Corrupted example '{}' in '{}'", name, example_path));
                 return;
             }
 
@@ -141,17 +141,17 @@ HelpWindow::HelpWindow(GUI::Window* parent)
     };
 }
 
-DeprecatedString HelpWindow::render(StringView key)
+ByteString HelpWindow::render(StringView key)
 {
     VERIFY(m_docs.has_object(key));
     auto& doc = m_docs.get_object(key).value();
 
-    auto name = doc.get_deprecated_string("name"sv).value_or({});
+    auto name = doc.get_byte_string("name"sv).value_or({});
     auto argc = doc.get_u32("argc"sv).value_or(0);
     VERIFY(doc.has_array("argnames"sv));
     auto& argnames = doc.get_array("argnames"sv).value();
 
-    auto docstring = doc.get_deprecated_string("doc"sv).value_or({});
+    auto docstring = doc.get_byte_string("doc"sv).value_or({});
 
     StringBuilder markdown_builder;
 
@@ -166,7 +166,7 @@ DeprecatedString HelpWindow::render(StringView key)
         markdown_builder.append("No required arguments.\n"sv);
 
     for (size_t i = 0; i < argc; ++i)
-        markdown_builder.appendff("- `{}`\n", argnames.at(i).to_deprecated_string());
+        markdown_builder.appendff("- `{}`\n", argnames.at(i).to_byte_string());
 
     if (argc > 0)
         markdown_builder.append("\n"sv);
@@ -175,7 +175,7 @@ DeprecatedString HelpWindow::render(StringView key)
         auto opt_count = argnames.size() - argc;
         markdown_builder.appendff("{} optional argument(s):\n", opt_count);
         for (size_t i = argc; i < (size_t)argnames.size(); ++i)
-            markdown_builder.appendff("- `{}`\n", argnames.at(i).to_deprecated_string());
+            markdown_builder.appendff("- `{}`\n", argnames.at(i).to_byte_string());
         markdown_builder.append("\n"sv);
     }
 
@@ -188,8 +188,8 @@ DeprecatedString HelpWindow::render(StringView key)
         VERIFY(examples.has_value());
         markdown_builder.append("# EXAMPLES\n"sv);
         examples->for_each_member([&](auto& text, auto& description_value) {
-            dbgln("```js\n{}\n```\n\n- {}\n", text, description_value.to_deprecated_string());
-            markdown_builder.appendff("```js\n{}\n```\n\n- {}\n", text, description_value.to_deprecated_string());
+            dbgln("```js\n{}\n```\n\n- {}\n", text, description_value.to_byte_string());
+            markdown_builder.appendff("```js\n{}\n```\n\n- {}\n", text, description_value.to_byte_string());
         });
     }
 
diff --git a/Userland/Applications/Spreadsheet/HelpWindow.h b/Userland/Applications/Spreadsheet/HelpWindow.h
index 41eb9360630..fe2b8765b09 100644
--- a/Userland/Applications/Spreadsheet/HelpWindow.h
+++ b/Userland/Applications/Spreadsheet/HelpWindow.h
@@ -32,7 +32,7 @@ public:
 
 private:
     static RefPtr<HelpWindow> s_the;
-    DeprecatedString render(StringView key);
+    ByteString render(StringView key);
     HelpWindow(GUI::Window* parent = nullptr);
 
     JsonObject m_docs;
diff --git a/Userland/Applications/Spreadsheet/ImportDialog.cpp b/Userland/Applications/Spreadsheet/ImportDialog.cpp
index fe2074b76b6..d37a3c47222 100644
--- a/Userland/Applications/Spreadsheet/ImportDialog.cpp
+++ b/Userland/Applications/Spreadsheet/ImportDialog.cpp
@@ -53,7 +53,7 @@ CSVImportDialogPage::CSVImportDialogPage(StringView csv)
     m_data_preview_error_label = m_page->body_widget().find_descendant_of_type_named<GUI::Label>("data_preview_error_label");
     m_data_preview_widget = m_page->body_widget().find_descendant_of_type_named<GUI::StackWidget>("data_preview_widget");
 
-    m_quote_escape_combo_box->set_model(GUI::ItemListModel<DeprecatedString>::create(m_quote_escape_items));
+    m_quote_escape_combo_box->set_model(GUI::ItemListModel<ByteString>::create(m_quote_escape_items));
 
     // By default, use commas, double quotes with repeat, and disable headers.
     m_delimiter_comma_radio->set_checked(true);
@@ -86,8 +86,8 @@ CSVImportDialogPage::CSVImportDialogPage(StringView csv)
 
 auto CSVImportDialogPage::make_reader() -> Optional<Reader::XSV>
 {
-    DeprecatedString delimiter;
-    DeprecatedString quote;
+    ByteString delimiter;
+    ByteString quote;
     Reader::ParserTraits::QuoteEscape quote_escape;
 
     // Delimiter
@@ -169,7 +169,7 @@ void CSVImportDialogPage::update_preview()
 
     Vector<String> headers;
     for (auto const& header : reader.headers())
-        headers.append(String::from_deprecated_string(header).release_value_but_fixme_should_propagate_errors());
+        headers.append(String::from_byte_string(header).release_value_but_fixme_should_propagate_errors());
 
     m_data_preview_table_view->set_model(
         GUI::ItemListModel<Reader::XSV::Row, Reader::XSV, Vector<String>>::create(reader, headers, min(8ul, reader.size())));
@@ -177,16 +177,16 @@ void CSVImportDialogPage::update_preview()
     m_data_preview_table_view->update();
 }
 
-ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> ImportDialog::make_and_run_for(GUI::Window& parent, StringView mime, String const& filename, Core::File& file, Workbook& workbook)
+ErrorOr<Vector<NonnullRefPtr<Sheet>>, ByteString> ImportDialog::make_and_run_for(GUI::Window& parent, StringView mime, String const& filename, Core::File& file, Workbook& workbook)
 {
     auto wizard = GUI::WizardDialog::create(&parent).release_value_but_fixme_should_propagate_errors();
     wizard->set_title("File Import Wizard");
     wizard->set_icon(GUI::Icon::default_icon("app-spreadsheet"sv).bitmap_for_size(16));
 
-    auto import_xsv = [&]() -> ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> {
+    auto import_xsv = [&]() -> ErrorOr<Vector<NonnullRefPtr<Sheet>>, ByteString> {
         auto contents_or_error = file.read_until_eof();
         if (contents_or_error.is_error())
-            return DeprecatedString::formatted("{}", contents_or_error.release_error());
+            return ByteString::formatted("{}", contents_or_error.release_error());
         CSVImportDialogPage page { contents_or_error.value() };
         wizard->replace_page(page.page());
         auto result = wizard->exec();
@@ -199,7 +199,7 @@ ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> ImportDialog::make_and_r
             if (reader.has_value()) {
                 reader->parse();
                 if (reader.value().has_error())
-                    return DeprecatedString::formatted("CSV Import failed: {}", reader.value().error_string());
+                    return ByteString::formatted("CSV Import failed: {}", reader.value().error_string());
 
                 auto sheet = Sheet::from_xsv(reader.value(), workbook);
                 if (sheet)
@@ -209,20 +209,20 @@ ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> ImportDialog::make_and_r
             return sheets;
         }
 
-        return DeprecatedString { "CSV Import was cancelled" };
+        return ByteString { "CSV Import was cancelled" };
     };
 
-    auto import_worksheet = [&]() -> ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> {
+    auto import_worksheet = [&]() -> ErrorOr<Vector<NonnullRefPtr<Sheet>>, ByteString> {
         auto contents_or_error = file.read_until_eof();
         if (contents_or_error.is_error())
-            return DeprecatedString::formatted("{}", contents_or_error.release_error());
+            return ByteString::formatted("{}", contents_or_error.release_error());
         auto json_value_option = JsonParser(contents_or_error.release_value()).parse();
         if (json_value_option.is_error())
-            return DeprecatedString::formatted("Failed to parse {}", filename);
+            return ByteString::formatted("Failed to parse {}", filename);
 
         auto& json_value = json_value_option.value();
         if (!json_value.is_array())
-            return DeprecatedString::formatted("Did not find a spreadsheet in {}", filename);
+            return ByteString::formatted("Did not find a spreadsheet in {}", filename);
 
         Vector<NonnullRefPtr<Sheet>> sheets;
 
@@ -247,7 +247,7 @@ ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> ImportDialog::make_and_r
     } else {
         auto page = GUI::WizardPage::create(
             "Import File Format"sv,
-            DeprecatedString::formatted("Select the format you wish to import '{}' as", LexicalPath::basename(filename.to_deprecated_string())))
+            ByteString::formatted("Select the format you wish to import '{}' as", LexicalPath::basename(filename.to_byte_string())))
                         .release_value_but_fixme_should_propagate_errors();
 
         page->on_next_page = [] { return nullptr; };
@@ -255,16 +255,16 @@ ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> ImportDialog::make_and_r
         page->body_widget().load_from_gml(select_format_page_gml).release_value_but_fixme_should_propagate_errors();
         auto format_combo_box = page->body_widget().find_descendant_of_type_named<GUI::ComboBox>("select_format_page_format_combo_box");
 
-        Vector<DeprecatedString> supported_formats {
+        Vector<ByteString> supported_formats {
             "CSV (text/csv)",
             "Spreadsheet Worksheet",
         };
-        format_combo_box->set_model(GUI::ItemListModel<DeprecatedString>::create(supported_formats));
+        format_combo_box->set_model(GUI::ItemListModel<ByteString>::create(supported_formats));
 
         wizard->push_page(page);
 
         if (wizard->exec() != GUI::Dialog::ExecResult::OK)
-            return DeprecatedString { "Import was cancelled" };
+            return ByteString { "Import was cancelled" };
 
         if (format_combo_box->selected_index() == 0)
             return import_xsv();
diff --git a/Userland/Applications/Spreadsheet/ImportDialog.h b/Userland/Applications/Spreadsheet/ImportDialog.h
index 6b883e47aef..f9e6c00bcc4 100644
--- a/Userland/Applications/Spreadsheet/ImportDialog.h
+++ b/Userland/Applications/Spreadsheet/ImportDialog.h
@@ -47,7 +47,7 @@ private:
     RefPtr<GUI::TableView> m_data_preview_table_view;
     RefPtr<GUI::Label> m_data_preview_error_label;
     RefPtr<GUI::StackWidget> m_data_preview_widget;
-    Vector<DeprecatedString> m_quote_escape_items {
+    Vector<ByteString> m_quote_escape_items {
         // Note: Keep in sync with Reader::ParserTraits::QuoteEscape.
         "Repeat",
         "Backslash",
@@ -55,7 +55,7 @@ private:
 };
 
 struct ImportDialog {
-    static ErrorOr<Vector<NonnullRefPtr<Sheet>>, DeprecatedString> make_and_run_for(GUI::Window& parent, StringView mime, String const& filename, Core::File& file, Workbook&);
+    static ErrorOr<Vector<NonnullRefPtr<Sheet>>, ByteString> make_and_run_for(GUI::Window& parent, StringView mime, String const& filename, Core::File& file, Workbook&);
 };
 
 }
diff --git a/Userland/Applications/Spreadsheet/JSIntegration.cpp b/Userland/Applications/Spreadsheet/JSIntegration.cpp
index 2cf362ede21..37fb98db489 100644
--- a/Userland/Applications/Spreadsheet/JSIntegration.cpp
+++ b/Userland/Applications/Spreadsheet/JSIntegration.cpp
@@ -197,7 +197,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::get_real_cell_contents)
     auto name_value = vm.argument(0);
     if (!name_value.is_string())
         return vm.throw_completion<JS::TypeError>("Expected a String argument to get_real_cell_contents()"sv);
-    auto position = sheet_object.m_sheet.parse_cell_name(name_value.as_string().deprecated_string());
+    auto position = sheet_object.m_sheet.parse_cell_name(name_value.as_string().byte_string());
     if (!position.has_value())
         return vm.throw_completion<JS::TypeError>("Invalid cell name"sv);
 
@@ -206,7 +206,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::get_real_cell_contents)
         return JS::js_undefined();
 
     if (cell->kind() == Spreadsheet::Cell::Kind::Formula)
-        return JS::PrimitiveString::create(vm, DeprecatedString::formatted("={}", cell->data()));
+        return JS::PrimitiveString::create(vm, ByteString::formatted("={}", cell->data()));
 
     return JS::PrimitiveString::create(vm, cell->data());
 }
@@ -226,7 +226,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::set_real_cell_contents)
     auto name_value = vm.argument(0);
     if (!name_value.is_string())
         return vm.throw_completion<JS::TypeError>("Expected the first argument of set_real_cell_contents() to be a String"sv);
-    auto position = sheet_object.m_sheet.parse_cell_name(name_value.as_string().deprecated_string());
+    auto position = sheet_object.m_sheet.parse_cell_name(name_value.as_string().byte_string());
     if (!position.has_value())
         return vm.throw_completion<JS::TypeError>("Invalid cell name"sv);
 
@@ -235,7 +235,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::set_real_cell_contents)
         return vm.throw_completion<JS::TypeError>("Expected the second argument of set_real_cell_contents() to be a String"sv);
 
     auto& cell = sheet_object.m_sheet.ensure(position.value());
-    auto new_contents = new_contents_value.as_string().deprecated_string();
+    auto new_contents = new_contents_value.as_string().byte_string();
     cell.set_data(new_contents);
     return JS::js_null();
 }
@@ -256,7 +256,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::parse_cell_name)
     auto name_value = vm.argument(0);
     if (!name_value.is_string())
         return vm.throw_completion<JS::TypeError>("Expected a String argument to parse_cell_name()"sv);
-    auto position = sheet_object.m_sheet.parse_cell_name(name_value.as_string().deprecated_string());
+    auto position = sheet_object.m_sheet.parse_cell_name(name_value.as_string().byte_string());
     if (!position.has_value())
         return JS::js_undefined();
 
@@ -302,7 +302,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::column_index)
     if (!column_name.is_string())
         return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "String");
 
-    auto column_name_str = column_name.as_string().deprecated_string();
+    auto column_name_str = column_name.as_string().byte_string();
 
     auto this_object = TRY(vm.this_value().to_object(vm));
 
@@ -327,7 +327,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::column_arithmetic)
     if (!column_name.is_string())
         return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "String");
 
-    auto column_name_str = column_name.as_string().deprecated_string();
+    auto column_name_str = column_name.as_string().byte_string();
 
     auto offset = TRY(vm.argument(1).to_number(vm));
     auto offset_number = static_cast<i32>(offset.as_double());
@@ -355,7 +355,7 @@ JS_DEFINE_NATIVE_FUNCTION(SheetGlobalObject::get_column_bound)
     if (!column_name.is_string())
         return vm.throw_completion<JS::TypeError>(JS::ErrorType::NotAnObjectOfType, "String");
 
-    auto column_name_str = column_name.as_string().deprecated_string();
+    auto column_name_str = column_name.as_string().byte_string();
     auto this_object = TRY(vm.this_value().to_object(vm));
 
     if (!is<SheetGlobalObject>(*this_object))
@@ -407,7 +407,7 @@ JS_DEFINE_NATIVE_FUNCTION(WorkbookObject::sheet)
     auto& workbook = workbook_object.m_workbook;
 
     if (name_value.is_string()) {
-        auto name = name_value.as_string().deprecated_string();
+        auto name = name_value.as_string().byte_string();
         for (auto& sheet : workbook.sheets()) {
             if (sheet->name() == name)
                 return JS::Value(&sheet->global_object());
diff --git a/Userland/Applications/Spreadsheet/JSIntegration.h b/Userland/Applications/Spreadsheet/JSIntegration.h
index 7122e160e27..d52922c39f4 100644
--- a/Userland/Applications/Spreadsheet/JSIntegration.h
+++ b/Userland/Applications/Spreadsheet/JSIntegration.h
@@ -14,7 +14,7 @@
 namespace Spreadsheet {
 
 struct FunctionAndArgumentIndex {
-    DeprecatedString function_name;
+    ByteString function_name;
     size_t argument_index { 0 };
 };
 Optional<FunctionAndArgumentIndex> get_function_and_argument_index(StringView source);
diff --git a/Userland/Applications/Spreadsheet/Position.h b/Userland/Applications/Spreadsheet/Position.h
index f798640a121..2c7d4feae0f 100644
--- a/Userland/Applications/Spreadsheet/Position.h
+++ b/Userland/Applications/Spreadsheet/Position.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Types.h>
 #include <AK/URL.h>
 
@@ -37,7 +37,7 @@ struct Position {
         return row == other.row && column == other.column;
     }
 
-    DeprecatedString to_cell_identifier(Sheet const& sheet) const;
+    ByteString to_cell_identifier(Sheet const& sheet) const;
     URL to_url(Sheet const& sheet) const;
 
     size_t column { 0 };
diff --git a/Userland/Applications/Spreadsheet/Readers/XSV.cpp b/Userland/Applications/Spreadsheet/Readers/XSV.cpp
index 92e692f654f..9b8289cbd76 100644
--- a/Userland/Applications/Spreadsheet/Readers/XSV.cpp
+++ b/Userland/Applications/Spreadsheet/Readers/XSV.cpp
@@ -25,9 +25,9 @@ void XSV::set_error(ReadError error)
         m_error = error;
 }
 
-Vector<DeprecatedString> XSV::headers() const
+Vector<ByteString> XSV::headers() const
 {
-    Vector<DeprecatedString> headers;
+    Vector<ByteString> headers;
     if (has_explicit_headers()) {
         for (auto& field : m_names)
             headers.append(field.is_string_view ? field.as_string_view : field.as_string.view());
@@ -37,7 +37,7 @@ Vector<DeprecatedString> XSV::headers() const
             return headers;
 
         for ([[maybe_unused]] auto& field : m_rows.first())
-            headers.append(DeprecatedString::empty());
+            headers.append(ByteString::empty());
     }
 
     return headers;
@@ -240,7 +240,7 @@ XSV::Field XSV::read_one_quoted_field()
         set_error(ReadError::QuoteFailure);
 
     if (is_copy)
-        return { {}, builder.to_deprecated_string(), false };
+        return { {}, builder.to_byte_string(), false };
 
     return { m_source.substring_view(start, end - start), {}, true };
 }
diff --git a/Userland/Applications/Spreadsheet/Readers/XSV.h b/Userland/Applications/Spreadsheet/Readers/XSV.h
index 31d08865a31..7dc3c275fd6 100644
--- a/Userland/Applications/Spreadsheet/Readers/XSV.h
+++ b/Userland/Applications/Spreadsheet/Readers/XSV.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/GenericLexer.h>
 #include <AK/StringView.h>
 #include <AK/Types.h>
@@ -31,8 +31,8 @@ ParserBehavior operator&(ParserBehavior left, ParserBehavior right);
 ParserBehavior operator|(ParserBehavior left, ParserBehavior right);
 
 struct ParserTraits {
-    DeprecatedString separator;
-    DeprecatedString quote { "\"" };
+    ByteString separator;
+    ByteString quote { "\"" };
     enum QuoteEscape {
         Repeat,
         Backslash,
@@ -73,7 +73,7 @@ public:
     void parse();
     bool has_error() const { return m_error != ReadError::None; }
     ReadError error() const { return m_error; }
-    DeprecatedString error_string() const
+    ByteString error_string() const
     {
         switch (m_error) {
 #define E(x, y)        \
@@ -87,7 +87,7 @@ public:
     }
 
     size_t size() const { return m_rows.size(); }
-    Vector<DeprecatedString> headers() const;
+    Vector<ByteString> headers() const;
     [[nodiscard]] bool has_explicit_headers() const { return (static_cast<u32>(m_behaviors) & static_cast<u32>(ParserBehavior::ReadHeaders)) != 0; }
 
     class Row {
@@ -185,7 +185,7 @@ public:
 private:
     struct Field {
         StringView as_string_view;
-        DeprecatedString as_string; // This member only used if the parser couldn't use the original source verbatim.
+        ByteString as_string; // This member only used if the parser couldn't use the original source verbatim.
         bool is_string_view { true };
 
         bool operator==(StringView other) const
diff --git a/Userland/Applications/Spreadsheet/Spreadsheet.cpp b/Userland/Applications/Spreadsheet/Spreadsheet.cpp
index 71680df5953..fceeeee9d23 100644
--- a/Userland/Applications/Spreadsheet/Spreadsheet.cpp
+++ b/Userland/Applications/Spreadsheet/Spreadsheet.cpp
@@ -61,7 +61,7 @@ Sheet::Sheet(Workbook& workbook)
             warnln("Spreadsheet: Failed to parse runtime code");
             for (auto& error : script_or_error.error()) {
                 // FIXME: This doesn't print hints anymore
-                warnln("SyntaxError: {}", error.to_deprecated_string());
+                warnln("SyntaxError: {}", error.to_byte_string());
             }
         } else {
             auto result = vm.bytecode_interpreter().run(script_or_error.value());
@@ -109,9 +109,9 @@ static Optional<size_t> convert_from_string(StringView str, unsigned base = 26,
     return value - 1;
 }
 
-DeprecatedString Sheet::add_column()
+ByteString Sheet::add_column()
 {
-    auto next_column = DeprecatedString::bijective_base_from(m_columns.size());
+    auto next_column = ByteString::bijective_base_from(m_columns.size());
     m_columns.append(next_column);
     return next_column;
 }
@@ -224,7 +224,7 @@ Optional<size_t> Sheet::column_index(StringView column_name) const
     return index;
 }
 
-Optional<DeprecatedString> Sheet::column_arithmetic(StringView column_name, int offset)
+Optional<ByteString> Sheet::column_arithmetic(StringView column_name, int offset)
 {
     auto maybe_index = column_index(column_name);
     if (!maybe_index.has_value())
@@ -255,17 +255,17 @@ Cell* Sheet::from_url(const URL& url)
 Optional<Position> Sheet::position_from_url(const URL& url) const
 {
     if (!url.is_valid()) {
-        dbgln("Invalid url: {}", url.to_deprecated_string());
+        dbgln("Invalid url: {}", url.to_byte_string());
         return {};
     }
 
     if (url.scheme() != "spreadsheet" || url.host() != "cell"_string) {
-        dbgln("Bad url: {}", url.to_deprecated_string());
+        dbgln("Bad url: {}", url.to_byte_string());
         return {};
     }
 
     // FIXME: Figure out a way to do this cross-process.
-    VERIFY(url.serialize_path() == DeprecatedString::formatted("/{}", getpid()));
+    VERIFY(url.serialize_path() == ByteString::formatted("/{}", getpid()));
 
     return parse_cell_name(url.fragment().value_or(String {}));
 }
@@ -372,7 +372,7 @@ RefPtr<Sheet> Sheet::from_json(JsonObject const& object, Workbook& workbook)
     auto sheet = adopt_ref(*new Sheet(workbook));
     auto rows = object.get_u32("rows"sv).value_or(default_row_count);
     auto columns = object.get_array("columns"sv);
-    auto name = object.get_deprecated_string("name"sv).value_or("Sheet");
+    auto name = object.get_byte_string("name"sv).value_or("Sheet");
     if (object.has("cells"sv) && !object.has_object("cells"sv))
         return {};
 
@@ -398,9 +398,9 @@ RefPtr<Sheet> Sheet::from_json(JsonObject const& object, Workbook& workbook)
     auto& parse_function = json.as_object().get_without_side_effects("parse").as_function();
 
     auto read_format = [](auto& format, auto const& obj) {
-        if (auto value = obj.get_deprecated_string("foreground_color"sv); value.has_value())
+        if (auto value = obj.get_byte_string("foreground_color"sv); value.has_value())
             format.foreground_color = Color::from_string(*value);
-        if (auto value = obj.get_deprecated_string("background_color"sv); value.has_value())
+        if (auto value = obj.get_byte_string("background_color"sv); value.has_value())
             format.background_color = Color::from_string(*value);
     };
 
@@ -412,26 +412,26 @@ RefPtr<Sheet> Sheet::from_json(JsonObject const& object, Workbook& workbook)
 
             auto position = position_option.value();
             auto& obj = value.as_object();
-            auto kind = obj.get_deprecated_string("kind"sv).value_or("LiteralString") == "LiteralString" ? Cell::LiteralString : Cell::Formula;
+            auto kind = obj.get_byte_string("kind"sv).value_or("LiteralString") == "LiteralString" ? Cell::LiteralString : Cell::Formula;
 
             OwnPtr<Cell> cell;
             switch (kind) {
             case Cell::LiteralString:
-                cell = make<Cell>(obj.get_deprecated_string("value"sv).value_or({}), position, *sheet);
+                cell = make<Cell>(obj.get_byte_string("value"sv).value_or({}), position, *sheet);
                 break;
             case Cell::Formula: {
                 auto& vm = sheet->vm();
-                auto value_or_error = JS::call(vm, parse_function, json, JS::PrimitiveString::create(vm, obj.get_deprecated_string("value"sv).value_or({})));
+                auto value_or_error = JS::call(vm, parse_function, json, JS::PrimitiveString::create(vm, obj.get_byte_string("value"sv).value_or({})));
                 if (value_or_error.is_error()) {
                     warnln("Failed to load previous value for cell {}, leaving as undefined", position.to_cell_identifier(sheet));
                     value_or_error = JS::js_undefined();
                 }
-                cell = make<Cell>(obj.get_deprecated_string("source"sv).value_or({}), value_or_error.release_value(), position, *sheet);
+                cell = make<Cell>(obj.get_byte_string("source"sv).value_or({}), value_or_error.release_value(), position, *sheet);
                 break;
             }
             }
 
-            auto type_name = obj.has("type"sv) ? obj.get_deprecated_string("type"sv).value_or({}) : "Numeric";
+            auto type_name = obj.has("type"sv) ? obj.get_byte_string("type"sv).value_or({}) : "Numeric";
             cell->set_type(type_name);
 
             auto type_meta = obj.get_object("type_metadata"sv);
@@ -440,9 +440,9 @@ RefPtr<Sheet> Sheet::from_json(JsonObject const& object, Workbook& workbook)
                 auto meta = cell->type_metadata();
                 if (auto value = meta_obj.get_i32("length"sv); value.has_value())
                     meta.length = value.value();
-                if (auto value = meta_obj.get_deprecated_string("format"sv); value.has_value())
+                if (auto value = meta_obj.get_byte_string("format"sv); value.has_value())
                     meta.format = value.value();
-                if (auto value = meta_obj.get_deprecated_string("alignment"sv); value.has_value()) {
+                if (auto value = meta_obj.get_byte_string("alignment"sv); value.has_value()) {
                     auto alignment = Gfx::text_alignment_from_string(*value);
                     if (alignment.has_value())
                         meta.alignment = alignment.value();
@@ -460,7 +460,7 @@ RefPtr<Sheet> Sheet::from_json(JsonObject const& object, Workbook& workbook)
                         return IterationDecision::Continue;
 
                     auto& fmt_obj = fmt_val.as_object();
-                    auto fmt_cond = fmt_obj.get_deprecated_string("condition"sv).value_or({});
+                    auto fmt_cond = fmt_obj.get_byte_string("condition"sv).value_or({});
                     if (fmt_cond.is_empty())
                         return IterationDecision::Continue;
 
@@ -513,7 +513,7 @@ Position Sheet::written_data_bounds(Optional<size_t> column_index) const
 bool Sheet::columns_are_standard() const
 {
     for (size_t i = 0; i < m_columns.size(); ++i) {
-        if (m_columns[i] != DeprecatedString::bijective_base_from(i))
+        if (m_columns[i] != ByteString::bijective_base_from(i))
             return false;
     }
 
@@ -527,9 +527,9 @@ JsonObject Sheet::to_json() const
 
     auto save_format = [](auto const& format, auto& obj) {
         if (format.foreground_color.has_value())
-            obj.set("foreground_color", format.foreground_color.value().to_deprecated_string());
+            obj.set("foreground_color", format.foreground_color.value().to_byte_string());
         if (format.background_color.has_value())
-            obj.set("background_color", format.background_color.value().to_deprecated_string());
+            obj.set("background_color", format.background_color.value().to_byte_string());
     };
 
     auto bottom_right = written_data_bounds();
@@ -547,7 +547,7 @@ JsonObject Sheet::to_json() const
         StringBuilder builder;
         builder.append(column(it.key.column));
         builder.appendff("{}", it.key.row);
-        auto key = builder.to_deprecated_string();
+        auto key = builder.to_byte_string();
 
         JsonObject data;
         data.set("kind", it.value->kind() == Cell::Kind::Formula ? "Formula" : "LiteralString");
@@ -556,7 +556,7 @@ JsonObject Sheet::to_json() const
             auto json = realm().global_object().get_without_side_effects("JSON");
             auto stringified_or_error = JS::call(vm(), json.as_object().get_without_side_effects("stringify").as_function(), json, it.value->evaluated_data());
             VERIFY(!stringified_or_error.is_error());
-            data.set("value", stringified_or_error.release_value().to_string_without_side_effects().to_deprecated_string());
+            data.set("value", stringified_or_error.release_value().to_string_without_side_effects().to_byte_string());
         } else {
             data.set("value", it.value->data());
         }
@@ -599,9 +599,9 @@ JsonObject Sheet::to_json() const
     return object;
 }
 
-Vector<Vector<DeprecatedString>> Sheet::to_xsv() const
+Vector<Vector<ByteString>> Sheet::to_xsv() const
 {
-    Vector<Vector<DeprecatedString>> data;
+    Vector<Vector<ByteString>> data;
 
     auto bottom_right = written_data_bounds();
 
@@ -609,7 +609,7 @@ Vector<Vector<DeprecatedString>> Sheet::to_xsv() const
     size_t column_count = m_columns.size();
     if (columns_are_standard()) {
         column_count = bottom_right.column + 1;
-        Vector<DeprecatedString> cols;
+        Vector<ByteString> cols;
         for (size_t i = 0; i < column_count; ++i)
             cols.append(m_columns[i]);
         data.append(move(cols));
@@ -618,7 +618,7 @@ Vector<Vector<DeprecatedString>> Sheet::to_xsv() const
     }
 
     for (size_t i = 0; i <= bottom_right.row; ++i) {
-        Vector<DeprecatedString> row;
+        Vector<ByteString> row;
         row.resize(column_count);
         for (size_t j = 0; j < column_count; ++j) {
             auto cell = at({ j, i });
@@ -646,7 +646,7 @@ RefPtr<Sheet> Sheet::from_xsv(Reader::XSV const& xsv, Workbook& workbook)
     } else {
         sheet->m_columns.ensure_capacity(cols.size());
         for (size_t i = 0; i < cols.size(); ++i)
-            sheet->m_columns.append(DeprecatedString::bijective_base_from(i));
+            sheet->m_columns.append(ByteString::bijective_base_from(i));
     }
     for (size_t i = 0; i < max(rows, Sheet::default_row_count); ++i)
         sheet->add_row();
@@ -706,7 +706,7 @@ JsonObject Sheet::gather_documentation() const
     return m_cached_documentation.value();
 }
 
-DeprecatedString Sheet::generate_inline_documentation_for(StringView function, size_t argument_index)
+ByteString Sheet::generate_inline_documentation_for(StringView function, size_t argument_index)
 {
     if (!m_cached_documentation.has_value())
         gather_documentation();
@@ -714,13 +714,13 @@ DeprecatedString Sheet::generate_inline_documentation_for(StringView function, s
     auto& docs = m_cached_documentation.value();
     auto entry = docs.get_object(function);
     if (!entry.has_value())
-        return DeprecatedString::formatted("{}(...???{})", function, argument_index);
+        return ByteString::formatted("{}(...???{})", function, argument_index);
 
     auto& entry_object = entry.value();
     size_t argc = entry_object.get_integer<int>("argc"sv).value_or(0);
     auto argnames_value = entry_object.get_array("argnames"sv);
     if (!argnames_value.has_value())
-        return DeprecatedString::formatted("{}(...{}???{})", function, argc, argument_index);
+        return ByteString::formatted("{}(...{}???{})", function, argc, argument_index);
     auto& argnames = argnames_value.value();
     StringBuilder builder;
     builder.appendff("{}(", function);
@@ -731,7 +731,7 @@ DeprecatedString Sheet::generate_inline_documentation_for(StringView function, s
             builder.append('<');
         else if (i >= argc)
             builder.append('[');
-        builder.append(argnames[i].to_deprecated_string());
+        builder.append(argnames[i].to_byte_string());
         if (i == argument_index)
             builder.append('>');
         else if (i >= argc)
@@ -739,12 +739,12 @@ DeprecatedString Sheet::generate_inline_documentation_for(StringView function, s
     }
 
     builder.append(')');
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Position::to_cell_identifier(Sheet const& sheet) const
+ByteString Position::to_cell_identifier(Sheet const& sheet) const
 {
-    return DeprecatedString::formatted("{}{}", sheet.column(column), row);
+    return ByteString::formatted("{}{}", sheet.column(column), row);
 }
 
 URL Position::to_url(Sheet const& sheet) const
@@ -752,12 +752,12 @@ URL Position::to_url(Sheet const& sheet) const
     URL url;
     url.set_scheme("spreadsheet"_string);
     url.set_host("cell"_string);
-    url.set_paths({ DeprecatedString::number(getpid()) });
-    url.set_fragment(String::from_deprecated_string(to_cell_identifier(sheet)).release_value());
+    url.set_paths({ ByteString::number(getpid()) });
+    url.set_fragment(String::from_byte_string(to_cell_identifier(sheet)).release_value());
     return url;
 }
 
-CellChange::CellChange(Cell& cell, DeprecatedString const& previous_data)
+CellChange::CellChange(Cell& cell, ByteString const& previous_data)
     : m_cell(cell)
     , m_previous_data(previous_data)
 {
diff --git a/Userland/Applications/Spreadsheet/Spreadsheet.h b/Userland/Applications/Spreadsheet/Spreadsheet.h
index 28e4bad61af..72d6a4fec31 100644
--- a/Userland/Applications/Spreadsheet/Spreadsheet.h
+++ b/Userland/Applications/Spreadsheet/Spreadsheet.h
@@ -9,7 +9,7 @@
 #include "Cell.h"
 #include "Forward.h"
 #include "Readers/XSV.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/HashTable.h>
 #include <AK/StringBuilder.h>
@@ -23,7 +23,7 @@ namespace Spreadsheet {
 
 class CellChange {
 public:
-    CellChange(Cell&, DeprecatedString const&);
+    CellChange(Cell&, ByteString const&);
     CellChange(Cell&, CellTypeMetadata const&);
 
     auto& cell() { return m_cell; }
@@ -34,8 +34,8 @@ public:
 
 private:
     Cell& m_cell;
-    DeprecatedString m_previous_data;
-    DeprecatedString m_new_data;
+    ByteString m_previous_data;
+    ByteString m_new_data;
     CellTypeMetadata m_previous_type_metadata;
     CellTypeMetadata m_new_type_metadata;
 };
@@ -51,7 +51,7 @@ public:
 
     Optional<Position> parse_cell_name(StringView) const;
     Optional<size_t> column_index(StringView column_name) const;
-    Optional<DeprecatedString> column_arithmetic(StringView column_name, int offset);
+    Optional<ByteString> column_arithmetic(StringView column_name, int offset);
 
     Cell* from_url(const URL&);
     Cell const* from_url(const URL& url) const { return const_cast<Sheet*>(this)->from_url(url); }
@@ -64,10 +64,10 @@ public:
     JsonObject to_json() const;
     static RefPtr<Sheet> from_json(JsonObject const&, Workbook&);
 
-    Vector<Vector<DeprecatedString>> to_xsv() const;
+    Vector<Vector<ByteString>> to_xsv() const;
     static RefPtr<Sheet> from_xsv(Reader::XSV const&, Workbook&);
 
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
     void set_name(StringView name) { m_name = name; }
 
     JsonObject gather_documentation() const;
@@ -89,17 +89,17 @@ public:
         if (auto cell = at(position))
             return *cell;
 
-        m_cells.set(position, make<Cell>(DeprecatedString::empty(), position, *this));
+        m_cells.set(position, make<Cell>(ByteString::empty(), position, *this));
         return *at(position);
     }
 
     size_t add_row();
-    DeprecatedString add_column();
+    ByteString add_column();
 
     size_t row_count() const { return m_rows; }
     size_t column_count() const { return m_columns.size(); }
-    Vector<DeprecatedString> const& columns() const { return m_columns; }
-    DeprecatedString const& column(size_t index)
+    Vector<ByteString> const& columns() const { return m_columns; }
+    ByteString const& column(size_t index)
     {
         for (size_t i = column_count(); i < index; ++i)
             add_column();
@@ -107,7 +107,7 @@ public:
         VERIFY(column_count() > index);
         return m_columns[index];
     }
-    DeprecatedString const& column(size_t index) const
+    ByteString const& column(size_t index) const
     {
         VERIFY(column_count() > index);
         return m_columns[index];
@@ -145,7 +145,7 @@ public:
 
     bool columns_are_standard() const;
 
-    DeprecatedString generate_inline_documentation_for(StringView function, size_t argument_index);
+    ByteString generate_inline_documentation_for(StringView function, size_t argument_index);
 
     JS::Realm& realm() const { return *m_root_execution_context->realm; }
     JS::VM& vm() const { return realm().vm(); }
@@ -154,8 +154,8 @@ private:
     explicit Sheet(Workbook&);
     explicit Sheet(StringView name, Workbook&);
 
-    DeprecatedString m_name;
-    Vector<DeprecatedString> m_columns;
+    ByteString m_name;
+    Vector<ByteString> m_columns;
     size_t m_rows { 0 };
     HashMap<Position, NonnullOwnPtr<Cell>> m_cells;
     HashTable<Position> m_selected_cells;
diff --git a/Userland/Applications/Spreadsheet/SpreadsheetModel.cpp b/Userland/Applications/Spreadsheet/SpreadsheetModel.cpp
index b7e330cdcbc..f1c17af961d 100644
--- a/Userland/Applications/Spreadsheet/SpreadsheetModel.cpp
+++ b/Userland/Applications/Spreadsheet/SpreadsheetModel.cpp
@@ -21,9 +21,9 @@ GUI::Variant SheetModel::data(const GUI::ModelIndex& index, GUI::ModelRole role)
     if (role == GUI::ModelRole::Display) {
         auto const* cell = m_sheet->at({ (size_t)index.column(), (size_t)index.row() });
         if (!cell)
-            return DeprecatedString::empty();
+            return ByteString::empty();
 
-        Function<DeprecatedString(JS::Value)> to_deprecated_string_as_exception = [&](JS::Value value) {
+        Function<ByteString(JS::Value)> to_byte_string_as_exception = [&](JS::Value value) {
             auto& vm = cell->sheet().global_object().vm();
             StringBuilder builder;
             builder.append("Error: "sv);
@@ -31,37 +31,37 @@ GUI::Variant SheetModel::data(const GUI::ModelIndex& index, GUI::ModelRole role)
                 auto& object = value.as_object();
                 if (is<JS::Error>(object)) {
                     auto message = object.get_without_side_effects("message");
-                    auto error = message.to_deprecated_string(vm);
+                    auto error = message.to_byte_string(vm);
                     if (error.is_throw_completion())
                         builder.append(message.to_string_without_side_effects());
                     else
                         builder.append(error.release_value());
-                    return builder.to_deprecated_string();
+                    return builder.to_byte_string();
                 }
             }
-            auto error_message = value.to_deprecated_string(vm);
+            auto error_message = value.to_byte_string(vm);
 
             if (error_message.is_throw_completion())
-                return to_deprecated_string_as_exception(*error_message.release_error().value());
+                return to_byte_string_as_exception(*error_message.release_error().value());
 
             builder.append(error_message.release_value());
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         };
 
         if (cell->kind() == Spreadsheet::Cell::Formula) {
             if (auto opt_throw_value = cell->thrown_value(); opt_throw_value.has_value())
-                return to_deprecated_string_as_exception(*opt_throw_value);
+                return to_byte_string_as_exception(*opt_throw_value);
         }
 
         auto display = cell->typed_display();
         if (display.is_error())
-            return to_deprecated_string_as_exception(*display.release_error().value());
+            return to_byte_string_as_exception(*display.release_error().value());
 
         return display.release_value();
     }
 
     if (role == GUI::ModelRole::MimeData)
-        return Position { (size_t)index.column(), (size_t)index.row() }.to_url(m_sheet).to_deprecated_string();
+        return Position { (size_t)index.column(), (size_t)index.row() }.to_url(m_sheet).to_byte_string();
 
     if (role == GUI::ModelRole::TextAlignment) {
         auto const* cell = m_sheet->at({ (size_t)index.column(), (size_t)index.row() });
@@ -131,7 +131,7 @@ GUI::Variant SheetModel::data(const GUI::ModelIndex& index, GUI::ModelRole role)
                 builder.appendff("  in cell '{}', at line {}, column {}\n", frame.source_range().filename().substring_view(5), frame.source_range().start.line, frame.source_range().start.column);
             }
         }
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 
     return {};
@@ -154,8 +154,8 @@ RefPtr<Core::MimeData> SheetModel::mime_data(const GUI::ModelSelection& selectio
 
     Position cursor_position { (size_t)cursor->column(), (size_t)cursor->row() };
     auto mime_data_buffer = mime_data->data("text/x-spreadsheet-data"sv);
-    auto new_data = DeprecatedString::formatted("{}\n{}",
-        cursor_position.to_url(m_sheet).to_deprecated_string(),
+    auto new_data = ByteString::formatted("{}\n{}",
+        cursor_position.to_url(m_sheet).to_byte_string(),
         StringView(mime_data_buffer));
     mime_data->set_data("text/x-spreadsheet-data"_string, new_data.to_byte_buffer());
 
@@ -167,7 +167,7 @@ ErrorOr<String> SheetModel::column_name(int index) const
     if (index < 0)
         return String {};
 
-    return TRY(String::from_deprecated_string(m_sheet->column(index)));
+    return TRY(String::from_byte_string(m_sheet->column(index)));
 }
 
 bool SheetModel::is_editable(const GUI::ModelIndex& index) const
@@ -185,7 +185,7 @@ void SheetModel::set_data(const GUI::ModelIndex& index, const GUI::Variant& valu
 
     auto& cell = m_sheet->ensure({ (size_t)index.column(), (size_t)index.row() });
     auto previous_data = cell.data();
-    cell.set_data(value.to_deprecated_string());
+    cell.set_data(value.to_byte_string());
     if (on_cell_data_change)
         on_cell_data_change(cell, previous_data);
     did_update(UpdateFlag::DontInvalidateIndices);
@@ -202,7 +202,7 @@ CellsUndoCommand::CellsUndoCommand(Vector<CellChange> cell_changes)
     m_cell_changes = cell_changes;
 }
 
-CellsUndoCommand::CellsUndoCommand(Cell& cell, DeprecatedString const& previous_data)
+CellsUndoCommand::CellsUndoCommand(Cell& cell, ByteString const& previous_data)
 {
     m_cell_changes.append(CellChange(cell, previous_data));
 }
diff --git a/Userland/Applications/Spreadsheet/SpreadsheetModel.h b/Userland/Applications/Spreadsheet/SpreadsheetModel.h
index 9a876e23cce..49267320703 100644
--- a/Userland/Applications/Spreadsheet/SpreadsheetModel.h
+++ b/Userland/Applications/Spreadsheet/SpreadsheetModel.h
@@ -34,7 +34,7 @@ public:
 
     void update();
 
-    Function<void(Cell&, DeprecatedString&)> on_cell_data_change;
+    Function<void(Cell&, ByteString&)> on_cell_data_change;
     Function<void(Vector<CellChange>)> on_cells_data_change;
 
 private:
@@ -48,7 +48,7 @@ private:
 
 class CellsUndoCommand : public GUI::Command {
 public:
-    CellsUndoCommand(Cell&, DeprecatedString const&);
+    CellsUndoCommand(Cell&, ByteString const&);
     CellsUndoCommand(Vector<CellChange>);
 
     virtual void undo() override;
diff --git a/Userland/Applications/Spreadsheet/SpreadsheetView.cpp b/Userland/Applications/Spreadsheet/SpreadsheetView.cpp
index a9210ce9ab8..dd3855d27b1 100644
--- a/Userland/Applications/Spreadsheet/SpreadsheetView.cpp
+++ b/Userland/Applications/Spreadsheet/SpreadsheetView.cpp
@@ -80,7 +80,7 @@ void InfinitelyScrollableTableView::mousemove_event(GUI::MouseEvent& event)
         if (!is_dragging()) {
             auto tooltip = model->data(index, static_cast<GUI::ModelRole>(SheetModel::Role::Tooltip));
             if (tooltip.is_string()) {
-                set_tooltip(MUST(String::from_deprecated_string(tooltip.as_string())));
+                set_tooltip(MUST(String::from_byte_string(tooltip.as_string())));
                 show_or_hide_tooltip();
             } else {
                 set_tooltip({});
@@ -495,7 +495,7 @@ void SpreadsheetView::TableCellPainter::paint(GUI::Painter& painter, Gfx::IntRec
     auto text_color = index.data(GUI::ModelRole::ForegroundColor).to_color(palette.color(m_table_view.foreground_role()));
     auto data = index.data();
     auto text_alignment = index.data(GUI::ModelRole::TextAlignment).to_text_alignment(Gfx::TextAlignment::CenterRight);
-    painter.draw_text(rect, data.to_deprecated_string(), m_table_view.font_for_index(index), text_alignment, text_color, Gfx::TextElision::Right);
+    painter.draw_text(rect, data.to_byte_string(), m_table_view.font_for_index(index), text_alignment, text_color, Gfx::TextElision::Right);
 }
 
 }
diff --git a/Userland/Applications/Spreadsheet/SpreadsheetWidget.cpp b/Userland/Applications/Spreadsheet/SpreadsheetWidget.cpp
index e88d52b5969..49293336155 100644
--- a/Userland/Applications/Spreadsheet/SpreadsheetWidget.cpp
+++ b/Userland/Applications/Spreadsheet/SpreadsheetWidget.cpp
@@ -99,7 +99,7 @@ SpreadsheetWidget::SpreadsheetWidget(GUI::Window& parent_window, Vector<NonnullR
         auto* sheet_ptr = m_tab_context_menu_sheet_view->sheet_if_available();
         VERIFY(sheet_ptr); // How did we get here without a sheet?
         auto& sheet = *sheet_ptr;
-        String new_name = String::from_deprecated_string(sheet.name()).release_value_but_fixme_should_propagate_errors();
+        String new_name = String::from_byte_string(sheet.name()).release_value_but_fixme_should_propagate_errors();
         if (GUI::InputBox::show(window(), new_name, {}, "Rename Sheet"sv, GUI::InputType::NonemptyText, "Name"sv) == GUI::Dialog::ExecResult::OK) {
             sheet.set_name(new_name);
             sheet.update();
@@ -166,7 +166,7 @@ SpreadsheetWidget::SpreadsheetWidget(GUI::Window& parent_window, Vector<NonnullR
     });
 
     m_save_as_action = GUI::CommonActions::make_save_as_action([&](auto&) {
-        DeprecatedString name = "workbook";
+        ByteString name = "workbook";
         auto response = FileSystemAccessClient::Client::the().save_file(window(), name, "sheets");
         if (response.is_error())
             return;
@@ -336,7 +336,7 @@ void SpreadsheetWidget::resize_event(GUI::ResizeEvent& event)
         m_inline_documentation_window->set_rect(m_cell_value_editor->screen_relative_rect().translated(0, m_cell_value_editor->height() + 7).inflated(6, 6));
 }
 
-void SpreadsheetWidget::clipboard_content_did_change(DeprecatedString const& mime_type)
+void SpreadsheetWidget::clipboard_content_did_change(ByteString const& mime_type)
 {
     if (auto* sheet = current_worksheet_if_available())
         m_paste_action->set_enabled(!sheet->selected_cells().is_empty() && mime_type.starts_with("text/"sv));
@@ -345,7 +345,7 @@ void SpreadsheetWidget::clipboard_content_did_change(DeprecatedString const& mim
 void SpreadsheetWidget::setup_tabs(Vector<NonnullRefPtr<Sheet>> new_sheets)
 {
     for (auto& sheet : new_sheets) {
-        auto& new_view = m_tab_widget->add_tab<SpreadsheetView>(String::from_deprecated_string(sheet->name()).release_value_but_fixme_should_propagate_errors(), sheet);
+        auto& new_view = m_tab_widget->add_tab<SpreadsheetView>(String::from_byte_string(sheet->name()).release_value_but_fixme_should_propagate_errors(), sheet);
         new_view.model()->on_cell_data_change = [&](auto& cell, auto& previous_data) {
             undo_stack().push(make<CellsUndoCommand>(cell, previous_data));
             window()->set_modified(true);
@@ -372,7 +372,7 @@ void SpreadsheetWidget::setup_tabs(Vector<NonnullRefPtr<Sheet>> new_sheets)
 
             if (selection.size() == 1) {
                 auto& position = selection.first();
-                m_current_cell_label->set_text(String::from_deprecated_string(position.to_cell_identifier(sheet)).release_value_but_fixme_should_propagate_errors());
+                m_current_cell_label->set_text(String::from_byte_string(position.to_cell_identifier(sheet)).release_value_but_fixme_should_propagate_errors());
 
                 auto& cell = sheet.ensure(position);
                 m_cell_value_editor->on_change = nullptr;
@@ -467,7 +467,7 @@ void SpreadsheetWidget::try_generate_tip_for_input_expression(StringView source,
     if (text.is_empty()) {
         m_inline_documentation_window->hide();
     } else {
-        m_inline_documentation_label->set_text(String::from_deprecated_string(text).release_value_but_fixme_should_propagate_errors());
+        m_inline_documentation_label->set_text(String::from_byte_string(text).release_value_but_fixme_should_propagate_errors());
         m_inline_documentation_window->show();
     }
 }
@@ -564,7 +564,7 @@ void SpreadsheetWidget::save(String const& filename, Core::File& file)
 {
     auto result = m_workbook->write_to_file(filename, file);
     if (result.is_error()) {
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Cannot save file: {}", result.error()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Cannot save file: {}", result.error()));
         return;
     }
     undo_stack().set_current_unmodified();
@@ -666,7 +666,7 @@ void SpreadsheetWidget::update_window_title()
         builder.append(current_filename());
     builder.append("[*] - Spreadsheet"sv);
 
-    window()->set_title(builder.to_deprecated_string());
+    window()->set_title(builder.to_byte_string());
 }
 
 void SpreadsheetWidget::clipboard_action(bool is_cut)
@@ -689,17 +689,17 @@ void SpreadsheetWidget::clipboard_action(bool is_cut)
     auto cursor = current_selection_cursor();
     if (cursor) {
         Spreadsheet::Position position { (size_t)cursor->column(), (size_t)cursor->row() };
-        url_builder.append(position.to_url(worksheet).to_deprecated_string());
+        url_builder.append(position.to_url(worksheet).to_byte_string());
         url_builder.append('\n');
     }
 
     for (auto& cell : cells) {
         if (first && !cursor) {
-            url_builder.append(cell.to_url(worksheet).to_deprecated_string());
+            url_builder.append(cell.to_url(worksheet).to_byte_string());
             url_builder.append('\n');
         }
 
-        url_builder.append(cell.to_url(worksheet).to_deprecated_string());
+        url_builder.append(cell.to_url(worksheet).to_byte_string());
         url_builder.append('\n');
 
         auto cell_data = worksheet.at(cell);
@@ -709,9 +709,9 @@ void SpreadsheetWidget::clipboard_action(bool is_cut)
             text_builder.append(cell_data->data());
         first = false;
     }
-    HashMap<DeprecatedString, DeprecatedString> metadata;
-    metadata.set("text/x-spreadsheet-data", url_builder.to_deprecated_string());
-    dbgln(url_builder.to_deprecated_string());
+    HashMap<ByteString, ByteString> metadata;
+    metadata.set("text/x-spreadsheet-data", url_builder.to_byte_string());
+    dbgln(url_builder.to_byte_string());
 
     GUI::Clipboard::the().set_data(text_builder.string_view().bytes(), "text/plain", move(metadata));
 }
diff --git a/Userland/Applications/Spreadsheet/SpreadsheetWidget.h b/Userland/Applications/Spreadsheet/SpreadsheetWidget.h
index 856789c8af9..d99ac857d28 100644
--- a/Userland/Applications/Spreadsheet/SpreadsheetWidget.h
+++ b/Userland/Applications/Spreadsheet/SpreadsheetWidget.h
@@ -29,7 +29,7 @@ public:
     void add_sheet();
     void add_sheet(NonnullRefPtr<Sheet>&&);
 
-    DeprecatedString const& current_filename() const { return m_workbook->current_filename(); }
+    ByteString const& current_filename() const { return m_workbook->current_filename(); }
     SpreadsheetView* current_view() { return static_cast<SpreadsheetView*>(m_tab_widget->active_widget()); }
     Sheet* current_worksheet_if_available() { return current_view() ? current_view()->sheet_if_available() : nullptr; }
     void update_window_title();
@@ -57,7 +57,7 @@ private:
     virtual void resize_event(GUI::ResizeEvent&) override;
 
     // ^GUI::Clipboard::ClipboardClient
-    virtual void clipboard_content_did_change(DeprecatedString const& mime_type) override;
+    virtual void clipboard_content_did_change(ByteString const& mime_type) override;
 
     explicit SpreadsheetWidget(GUI::Window& window, Vector<NonnullRefPtr<Sheet>>&& sheets = {}, bool should_add_sheet_if_empty = true);
 
diff --git a/Userland/Applications/Spreadsheet/Workbook.cpp b/Userland/Applications/Spreadsheet/Workbook.cpp
index 1706afd72ae..f2c8b40fe5a 100644
--- a/Userland/Applications/Spreadsheet/Workbook.cpp
+++ b/Userland/Applications/Spreadsheet/Workbook.cpp
@@ -41,7 +41,7 @@ Workbook::Workbook(Vector<NonnullRefPtr<Sheet>>&& sheets, GUI::Window& parent_wi
     m_vm->set_dynamic_imports_allowed(true);
 }
 
-bool Workbook::set_filename(DeprecatedString const& filename)
+bool Workbook::set_filename(ByteString const& filename)
 {
     if (m_current_filename == filename)
         return false;
@@ -50,14 +50,14 @@ bool Workbook::set_filename(DeprecatedString const& filename)
     return true;
 }
 
-ErrorOr<void, DeprecatedString> Workbook::open_file(String const& filename, Core::File& file)
+ErrorOr<void, ByteString> Workbook::open_file(String const& filename, Core::File& file)
 {
     auto mime = Core::guess_mime_type_based_on_filename(filename);
 
     // Make an import dialog, we might need to import it.
     m_sheets = TRY(ImportDialog::make_and_run_for(m_parent_window, mime, filename, file, *this));
 
-    set_filename(filename.to_deprecated_string());
+    set_filename(filename.to_byte_string());
 
     return {};
 }
@@ -67,14 +67,14 @@ ErrorOr<void> Workbook::write_to_file(String const& filename, Core::File& stream
     auto mime = Core::guess_mime_type_based_on_filename(filename);
 
     // Make an export dialog, we might need to import it.
-    TRY(ExportDialog::make_and_run_for(mime, stream, filename.to_deprecated_string(), *this));
+    TRY(ExportDialog::make_and_run_for(mime, stream, filename.to_byte_string(), *this));
 
-    set_filename(filename.to_deprecated_string());
+    set_filename(filename.to_byte_string());
     set_dirty(false);
     return {};
 }
 
-ErrorOr<bool, DeprecatedString> Workbook::import_file(String const& filename, Core::File& file)
+ErrorOr<bool, ByteString> Workbook::import_file(String const& filename, Core::File& file)
 {
     auto mime = Core::guess_mime_type_based_on_filename(filename);
 
diff --git a/Userland/Applications/Spreadsheet/Workbook.h b/Userland/Applications/Spreadsheet/Workbook.h
index 864eba764a6..70dbb47d97f 100644
--- a/Userland/Applications/Spreadsheet/Workbook.h
+++ b/Userland/Applications/Spreadsheet/Workbook.h
@@ -15,13 +15,13 @@ class Workbook {
 public:
     Workbook(Vector<NonnullRefPtr<Sheet>>&& sheets, GUI::Window& parent_window);
 
-    ErrorOr<void, DeprecatedString> open_file(String const& filename, Core::File&);
+    ErrorOr<void, ByteString> open_file(String const& filename, Core::File&);
     ErrorOr<void> write_to_file(String const& filename, Core::File&);
 
-    ErrorOr<bool, DeprecatedString> import_file(String const& filename, Core::File&);
+    ErrorOr<bool, ByteString> import_file(String const& filename, Core::File&);
 
-    DeprecatedString const& current_filename() const { return m_current_filename; }
-    bool set_filename(DeprecatedString const& filename);
+    ByteString const& current_filename() const { return m_current_filename; }
+    bool set_filename(ByteString const& filename);
     bool dirty() { return m_dirty; }
     void set_dirty(bool dirty) { m_dirty = dirty; }
 
@@ -50,7 +50,7 @@ private:
     NonnullOwnPtr<JS::ExecutionContext> m_main_execution_context;
     GUI::Window& m_parent_window;
 
-    DeprecatedString m_current_filename;
+    ByteString m_current_filename;
     bool m_dirty { false };
 };
 
diff --git a/Userland/Applications/Spreadsheet/Writers/Test/TestXSVWriter.cpp b/Userland/Applications/Spreadsheet/Writers/Test/TestXSVWriter.cpp
index 8b09cf579d4..d57dc1768aa 100644
--- a/Userland/Applications/Spreadsheet/Writers/Test/TestXSVWriter.cpp
+++ b/Userland/Applications/Spreadsheet/Writers/Test/TestXSVWriter.cpp
@@ -52,7 +52,7 @@ TEST_CASE(can_write_with_header)
 
 TEST_CASE(can_write_with_different_behaviors)
 {
-    Vector<Vector<DeprecatedString>> data = {
+    Vector<Vector<ByteString>> data = {
         { "Well", "Hello\"", "Friends" },
         { "We\"ll", "Hello,", "   Friends" },
     };
diff --git a/Userland/Applications/Spreadsheet/Writers/XSV.h b/Userland/Applications/Spreadsheet/Writers/XSV.h
index 2ea61a0e207..5b13b468a64 100644
--- a/Userland/Applications/Spreadsheet/Writers/XSV.h
+++ b/Userland/Applications/Spreadsheet/Writers/XSV.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/GenericLexer.h>
 #include <AK/OwnPtr.h>
 #include <AK/Stream.h>
@@ -26,8 +26,8 @@ enum class WriterBehavior : u32 {
 AK_ENUM_BITWISE_OPERATORS(WriterBehavior);
 
 struct WriterTraits {
-    DeprecatedString separator;
-    DeprecatedString quote { "\"" };
+    ByteString separator;
+    ByteString quote { "\"" };
     enum QuoteEscape {
         Repeat,
         Backslash,
@@ -121,7 +121,7 @@ private:
     template<typename T>
     ErrorOr<void> write_entry(T&& entry)
     {
-        auto string = DeprecatedString::formatted("{}", FormatIfSupported(entry));
+        auto string = ByteString::formatted("{}", FormatIfSupported(entry));
 
         auto safe_to_write_normally = !has_flag(m_behaviors, WriterBehavior::QuoteAll)
             && !string.contains('\n')
diff --git a/Userland/Applications/SystemMonitor/GraphWidget.h b/Userland/Applications/SystemMonitor/GraphWidget.h
index e8831343703..67eeef3a98b 100644
--- a/Userland/Applications/SystemMonitor/GraphWidget.h
+++ b/Userland/Applications/SystemMonitor/GraphWidget.h
@@ -26,7 +26,7 @@ public:
     struct ValueFormat {
         Gfx::ColorRole graph_color_role { Gfx::ColorRole::Base };
         Color text_shadow_color { Color::Transparent };
-        Function<DeprecatedString(u64)> text_formatter;
+        Function<ByteString(u64)> text_formatter;
     };
     void set_value_format(size_t index, ValueFormat&& format)
     {
diff --git a/Userland/Applications/SystemMonitor/MemoryStatsWidget.cpp b/Userland/Applications/SystemMonitor/MemoryStatsWidget.cpp
index 8d6c6246e6b..e5543b55f02 100644
--- a/Userland/Applications/SystemMonitor/MemoryStatsWidget.cpp
+++ b/Userland/Applications/SystemMonitor/MemoryStatsWidget.cpp
@@ -71,7 +71,7 @@ void MemoryStatsWidget::set_graph_widget(GraphWidget& graph)
     m_graph = &graph;
 }
 
-void MemoryStatsWidget::set_graph_widget_via_name(DeprecatedString name)
+void MemoryStatsWidget::set_graph_widget_via_name(ByteString name)
 {
     m_graph_widget_name = move(name);
     if (!m_graph_widget_name.is_empty()) {
@@ -87,7 +87,7 @@ void MemoryStatsWidget::set_graph_widget_via_name(DeprecatedString name)
     }
 }
 
-DeprecatedString MemoryStatsWidget::graph_widget_name()
+ByteString MemoryStatsWidget::graph_widget_name()
 {
     if (m_graph)
         return m_graph->name();
diff --git a/Userland/Applications/SystemMonitor/MemoryStatsWidget.h b/Userland/Applications/SystemMonitor/MemoryStatsWidget.h
index 3305aaf0d8d..52d67f8ab3a 100644
--- a/Userland/Applications/SystemMonitor/MemoryStatsWidget.h
+++ b/Userland/Applications/SystemMonitor/MemoryStatsWidget.h
@@ -22,8 +22,8 @@ public:
 
     void set_graph_widget(GraphWidget& graph);
 
-    void set_graph_widget_via_name(DeprecatedString name);
-    DeprecatedString graph_widget_name();
+    void set_graph_widget_via_name(ByteString name);
+    ByteString graph_widget_name();
 
     void refresh();
 
@@ -33,7 +33,7 @@ private:
 
     GraphWidget* m_graph;
     // Is null if we have a valid graph
-    DeprecatedString m_graph_widget_name {};
+    ByteString m_graph_widget_name {};
     RefPtr<GUI::Label> m_physical_pages_label;
     RefPtr<GUI::Label> m_physical_pages_committed_label;
     RefPtr<GUI::Label> m_kmalloc_space_label;
diff --git a/Userland/Applications/SystemMonitor/NetworkStatisticsWidget.cpp b/Userland/Applications/SystemMonitor/NetworkStatisticsWidget.cpp
index bb42d61450f..bfdf4dcd353 100644
--- a/Userland/Applications/SystemMonitor/NetworkStatisticsWidget.cpp
+++ b/Userland/Applications/SystemMonitor/NetworkStatisticsWidget.cpp
@@ -48,22 +48,22 @@ NetworkStatisticsWidget::NetworkStatisticsWidget()
                 if (!object.get_bool("link_up"sv).value_or(false))
                     return *m_network_link_down_bitmap;
                 else
-                    return object.get_deprecated_string("ipv4_address"sv).value_or("").is_empty() ? *m_network_disconnected_bitmap : *m_network_connected_bitmap;
+                    return object.get_byte_string("ipv4_address"sv).value_or("").is_empty() ? *m_network_disconnected_bitmap : *m_network_connected_bitmap;
             });
         net_adapters_fields.empend("name", "Name"_string, Gfx::TextAlignment::CenterLeft);
         net_adapters_fields.empend("class_name", "Class"_string, Gfx::TextAlignment::CenterLeft);
         net_adapters_fields.empend("mac_address", "MAC"_string, Gfx::TextAlignment::CenterLeft);
         net_adapters_fields.empend("Link status"_string, Gfx::TextAlignment::CenterLeft,
-            [](JsonObject const& object) -> DeprecatedString {
+            [](JsonObject const& object) -> ByteString {
                 if (!object.get_bool("link_up"sv).value_or(false))
                     return "Down";
 
-                return DeprecatedString::formatted("{} Mb/s {}-duplex", object.get_i32("link_speed"sv).value_or(0),
+                return ByteString::formatted("{} Mb/s {}-duplex", object.get_i32("link_speed"sv).value_or(0),
                     object.get_bool("link_full_duplex"sv).value_or(false) ? "full"sv : "half"sv);
             });
         net_adapters_fields.empend("IPv4"_string, Gfx::TextAlignment::CenterLeft,
-            [](JsonObject const& object) -> DeprecatedString {
-                return object.get_deprecated_string("ipv4_address"sv).value_or(""sv);
+            [](JsonObject const& object) -> ByteString {
+                return object.get_byte_string("ipv4_address"sv).value_or(""sv);
             });
         net_adapters_fields.empend("packets_in", "Pkt In"_string, Gfx::TextAlignment::CenterRight);
         net_adapters_fields.empend("packets_out", "Pkt Out"_string, Gfx::TextAlignment::CenterRight);
diff --git a/Userland/Applications/SystemMonitor/ProcessFileDescriptorMapWidget.cpp b/Userland/Applications/SystemMonitor/ProcessFileDescriptorMapWidget.cpp
index 7d50edc8d13..162d9b13d53 100644
--- a/Userland/Applications/SystemMonitor/ProcessFileDescriptorMapWidget.cpp
+++ b/Userland/Applications/SystemMonitor/ProcessFileDescriptorMapWidget.cpp
@@ -53,7 +53,7 @@ void ProcessFileDescriptorMapWidget::set_pid(pid_t pid)
     if (m_pid == pid)
         return;
     m_pid = pid;
-    m_model->set_json_path(DeprecatedString::formatted("/proc/{}/fds", m_pid));
+    m_model->set_json_path(ByteString::formatted("/proc/{}/fds", m_pid));
 }
 
 }
diff --git a/Userland/Applications/SystemMonitor/ProcessMemoryMapWidget.cpp b/Userland/Applications/SystemMonitor/ProcessMemoryMapWidget.cpp
index d787760df7d..1e4bd47addc 100644
--- a/Userland/Applications/SystemMonitor/ProcessMemoryMapWidget.cpp
+++ b/Userland/Applications/SystemMonitor/ProcessMemoryMapWidget.cpp
@@ -25,7 +25,7 @@ public:
     virtual void paint(GUI::Painter& painter, Gfx::IntRect const& a_rect, Gfx::Palette const&, const GUI::ModelIndex& index) override
     {
         auto rect = a_rect.shrunken(2, 2);
-        auto pagemap = index.data(GUI::ModelRole::Custom).to_deprecated_string();
+        auto pagemap = index.data(GUI::ModelRole::Custom).to_byte_string();
 
         float scale_factor = (float)pagemap.length() / (float)rect.width();
 
@@ -58,7 +58,7 @@ ErrorOr<NonnullRefPtr<ProcessMemoryMapWidget>> ProcessMemoryMapWidget::try_creat
     Vector<GUI::JsonArrayModel::FieldSpec> pid_vm_fields;
     TRY(pid_vm_fields.try_empend(
         "Address"_string, Gfx::TextAlignment::CenterLeft,
-        [](auto& object) { return DeprecatedString::formatted("{:p}", object.get_u64("address"sv).value_or(0)); },
+        [](auto& object) { return ByteString::formatted("{:p}", object.get_u64("address"sv).value_or(0)); },
         [](auto& object) { return object.get_u64("address"sv).value_or(0); }));
     TRY(pid_vm_fields.try_empend("size", "Size"_string, Gfx::TextAlignment::CenterRight));
     TRY(pid_vm_fields.try_empend("amount_resident", "Resident"_string, Gfx::TextAlignment::CenterRight));
@@ -77,10 +77,10 @@ ErrorOr<NonnullRefPtr<ProcessMemoryMapWidget>> ProcessMemoryMapWidget::try_creat
             builder.append('C');
         if (object.get_bool("stack"sv).value_or(false))
             builder.append('T');
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }));
     TRY(pid_vm_fields.try_empend("VMObject type"_string, Gfx::TextAlignment::CenterLeft, [](auto& object) {
-        auto type = object.get_deprecated_string("vmobject"sv).value_or({});
+        auto type = object.get_byte_string("vmobject"sv).value_or({});
         if (type.ends_with("VMObject"sv))
             type = type.substring(0, type.length() - 8);
         return type;
@@ -99,7 +99,7 @@ ErrorOr<NonnullRefPtr<ProcessMemoryMapWidget>> ProcessMemoryMapWidget::try_creat
             return GUI::Variant(0);
         },
         [](JsonObject const& object) {
-            auto pagemap = object.get_deprecated_string("pagemap"sv).value_or({});
+            auto pagemap = object.get_byte_string("pagemap"sv).value_or({});
             return pagemap;
         }));
     TRY(pid_vm_fields.try_empend("cow_pages", "# CoW"_string, Gfx::TextAlignment::CenterRight));
@@ -121,7 +121,7 @@ void ProcessMemoryMapWidget::set_pid(pid_t pid)
     if (m_pid == pid)
         return;
     m_pid = pid;
-    m_json_model->set_json_path(DeprecatedString::formatted("/proc/{}/vm", pid));
+    m_json_model->set_json_path(ByteString::formatted("/proc/{}/vm", pid));
 }
 
 void ProcessMemoryMapWidget::refresh()
diff --git a/Userland/Applications/SystemMonitor/ProcessModel.cpp b/Userland/Applications/SystemMonitor/ProcessModel.cpp
index 45a5bc8055b..ea2dc96b69f 100644
--- a/Userland/Applications/SystemMonitor/ProcessModel.cpp
+++ b/Userland/Applications/SystemMonitor/ProcessModel.cpp
@@ -288,12 +288,12 @@ GUI::Variant ProcessModel::data(GUI::ModelIndex const& index, GUI::ModelRole rol
         case Column::PurgeableNonvolatile:
             return human_readable_size(thread.current_state.amount_purgeable_nonvolatile);
         case Column::CPU:
-            return DeprecatedString::formatted("{:.2}", thread.current_state.cpu_percent);
+            return ByteString::formatted("{:.2}", thread.current_state.cpu_percent);
         case Column::Processor:
             return thread.current_state.cpu;
         case Column::Name:
             if (thread.current_state.kernel)
-                return DeprecatedString::formatted("{} (*)", thread.current_state.name);
+                return ByteString::formatted("{} (*)", thread.current_state.name);
             return thread.current_state.name;
         case Column::Command:
             return thread.current_state.command.visit([](String const& cmdline) { return cmdline; }, [](auto const&) { return ""_string; });
diff --git a/Userland/Applications/SystemMonitor/ProcessModel.h b/Userland/Applications/SystemMonitor/ProcessModel.h
index 9f6a9f9d7f1..f6c95f1ad73 100644
--- a/Userland/Applications/SystemMonitor/ProcessModel.h
+++ b/Userland/Applications/SystemMonitor/ProcessModel.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/Vector.h>
 #include <LibGUI/Icon.h>
@@ -110,14 +110,14 @@ private:
         u64 time_user { 0 };
         u64 time_kernel { 0 };
         bool kernel { false };
-        DeprecatedString executable { "" };
-        DeprecatedString name { "" };
+        ByteString executable { "" };
+        ByteString name { "" };
         Variant<String, EmptyCommand> command { EmptyCommand::NotInitialized };
         uid_t uid { 0 };
-        DeprecatedString state { "" };
-        DeprecatedString user { "" };
-        DeprecatedString pledge { "" };
-        DeprecatedString veil { "" };
+        ByteString state { "" };
+        ByteString user { "" };
+        ByteString pledge { "" };
+        ByteString veil { "" };
         u32 cpu { 0 };
         u32 priority { 0 };
         size_t amount_virtual { 0 };
diff --git a/Userland/Applications/SystemMonitor/ProcessUnveiledPathsWidget.cpp b/Userland/Applications/SystemMonitor/ProcessUnveiledPathsWidget.cpp
index bef2f50fdd4..8ffe69514a5 100644
--- a/Userland/Applications/SystemMonitor/ProcessUnveiledPathsWidget.cpp
+++ b/Userland/Applications/SystemMonitor/ProcessUnveiledPathsWidget.cpp
@@ -36,7 +36,7 @@ void ProcessUnveiledPathsWidget::set_pid(pid_t pid)
     if (m_pid == pid)
         return;
     m_pid = pid;
-    m_model->set_json_path(DeprecatedString::formatted("/proc/{}/unveil", m_pid));
+    m_model->set_json_path(ByteString::formatted("/proc/{}/unveil", m_pid));
 }
 
 }
diff --git a/Userland/Applications/SystemMonitor/ThreadStackWidget.cpp b/Userland/Applications/SystemMonitor/ThreadStackWidget.cpp
index 4e3c2210c84..9df72c865b9 100644
--- a/Userland/Applications/SystemMonitor/ThreadStackWidget.cpp
+++ b/Userland/Applications/SystemMonitor/ThreadStackWidget.cpp
@@ -49,7 +49,7 @@ public:
         auto& symbol = m_symbols[model_index.row()];
         switch (model_index.column()) {
         case Column::Address:
-            return DeprecatedString::formatted("{:p}", symbol.address);
+            return ByteString::formatted("{:p}", symbol.address);
         case Column::Object:
             return symbol.object;
         case Column::Symbol:
diff --git a/Userland/Applications/SystemMonitor/main.cpp b/Userland/Applications/SystemMonitor/main.cpp
index c39b89952b7..16835ab1d6f 100644
--- a/Userland/Applications/SystemMonitor/main.cpp
+++ b/Userland/Applications/SystemMonitor/main.cpp
@@ -75,7 +75,7 @@ public:
         auto percentage = index.data(GUI::ModelRole::Custom).to_i32();
 
         auto data = index.data();
-        DeprecatedString text;
+        ByteString text;
         if (data.is_string())
             text = data.as_string();
         Gfx::StylePainter::paint_progressbar(painter, rect, palette, 0, 100, percentage, text);
@@ -133,7 +133,7 @@ public:
                     size_builder.append(' ');
                     size_builder.append(human_readable_size(object.get_u64("total_block_count"sv).value_or(0) * object.get_u64("block_size"sv).value_or(0)));
                     size_builder.append(' ');
-                    return size_builder.to_deprecated_string();
+                    return size_builder.to_byte_string();
                 },
                 [](JsonObject const& object) {
                     return object.get_u64("total_block_count"sv).value_or(0) * object.get_u64("block_size"sv).value_or(0);
@@ -194,8 +194,8 @@ public:
                 check(MS_AXALLOWED, "axallowed"sv);
                 check(MS_NOREGULAR, "noregular"sv);
                 if (builder.string_view().is_empty())
-                    return DeprecatedString("defaults");
-                return builder.to_deprecated_string();
+                    return ByteString("defaults");
+                return builder.to_byte_string();
             });
             df_fields.empend("free_block_count", "Free blocks"_string, Gfx::TextAlignment::CenterRight);
             df_fields.empend("total_block_count", "Total blocks"_string, Gfx::TextAlignment::CenterRight);
@@ -342,11 +342,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return pid_index.data().to_i32();
     };
 
-    auto selected_name = [&](ProcessModel::Column column) -> DeprecatedString {
+    auto selected_name = [&](ProcessModel::Column column) -> ByteString {
         if (process_table_view.selection().is_empty())
             return {};
         auto pid_index = process_table_view.model()->index(process_table_view.selection().first().row(), column, process_table_view.selection().first().parent());
-        return pid_index.data().to_deprecated_string();
+        return pid_index.data().to_byte_string();
     };
 
     auto kill_action = GUI::Action::create(
@@ -354,7 +354,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             pid_t pid = selected_id(ProcessModel::Column::PID);
             if (pid == -1)
                 return;
-            auto rc = GUI::MessageBox::show(window, DeprecatedString::formatted("Do you really want to kill \"{}\" (PID {})?", selected_name(ProcessModel::Column::Name), pid), "System Monitor"sv, GUI::MessageBox::Type::Question, GUI::MessageBox::InputType::YesNo);
+            auto rc = GUI::MessageBox::show(window, ByteString::formatted("Do you really want to kill \"{}\" (PID {})?", selected_name(ProcessModel::Column::Name), pid), "System Monitor"sv, GUI::MessageBox::Type::Question, GUI::MessageBox::InputType::YesNo);
             if (rc == GUI::Dialog::ExecResult::Yes)
                 kill(pid, SIGKILL);
         },
@@ -365,7 +365,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             pid_t pid = selected_id(ProcessModel::Column::PID);
             if (pid == -1)
                 return;
-            auto rc = GUI::MessageBox::show(window, DeprecatedString::formatted("Do you really want to stop \"{}\" (PID {})?", selected_name(ProcessModel::Column::Name), pid), "System Monitor"sv, GUI::MessageBox::Type::Question, GUI::MessageBox::InputType::YesNo);
+            auto rc = GUI::MessageBox::show(window, ByteString::formatted("Do you really want to stop \"{}\" (PID {})?", selected_name(ProcessModel::Column::Name), pid), "System Monitor"sv, GUI::MessageBox::Type::Question, GUI::MessageBox::InputType::YesNo);
             if (rc == GUI::Dialog::ExecResult::Yes)
                 kill(pid, SIGSTOP);
         },
@@ -385,7 +385,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             pid_t pid = selected_id(ProcessModel::Column::PID);
             if (pid == -1)
                 return;
-            auto pid_string = DeprecatedString::number(pid);
+            auto pid_string = ByteString::number(pid);
             GUI::Process::spawn_or_show_error(window, "/bin/Profiler"sv, Array { "--pid", pid_string.characters() });
         },
         &process_table_view);
@@ -395,7 +395,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             pid_t pid = selected_id(ProcessModel::Column::PID);
             if (pid == -1)
                 return;
-            auto pid_string = DeprecatedString::number(pid);
+            auto pid_string = ByteString::number(pid);
             GUI::Process::spawn_or_show_error(window, "/bin/HackStudio"sv, Array { "--pid", pid_string.characters() });
         },
         &process_table_view);
@@ -452,7 +452,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     frequency_action_group.set_exclusive(true);
 
     auto make_frequency_action = [&](int seconds) -> ErrorOr<void> {
-        auto action = GUI::Action::create_checkable(DeprecatedString::formatted("&{} Sec", seconds), [&refresh_timer, seconds](auto&) {
+        auto action = GUI::Action::create_checkable(ByteString::formatted("&{} Sec", seconds), [&refresh_timer, seconds](auto&) {
             Config::write_i32("SystemMonitor"sv, "Monitor"sv, "Frequency"sv, seconds);
             refresh_timer.restart(seconds * 1000);
         });
@@ -526,7 +526,7 @@ ErrorOr<NonnullRefPtr<GUI::Window>> build_process_window(pid_t pid)
 {
     auto window = GUI::Window::construct();
     window->resize(480, 360);
-    window->set_title(DeprecatedString::formatted("PID {} - System Monitor", pid));
+    window->set_title(ByteString::formatted("PID {} - System Monitor", pid));
 
     auto app_icon = TRY(GUI::Icon::try_create_default_icon("app-system-monitor"sv));
     window->set_icon(app_icon.bitmap_for_size(16));
@@ -548,7 +548,7 @@ ErrorOr<NonnullRefPtr<GUI::Window>> build_process_window(pid_t pid)
         main_widget->find_descendant_of_type_named<GUI::ImageWidget>("process_icon")->set_bitmap(icon_data.as_icon().bitmap_for_size(32));
     }
 
-    main_widget->find_descendant_of_type_named<GUI::Label>("process_name")->set_text(TRY(String::formatted("{} (PID {})", process_index.sibling_at_column(ProcessModel::Column::Name).data().to_deprecated_string(), pid)));
+    main_widget->find_descendant_of_type_named<GUI::Label>("process_name")->set_text(TRY(String::formatted("{} (PID {})", process_index.sibling_at_column(ProcessModel::Column::Name).data().to_byte_string(), pid)));
 
     main_widget->find_descendant_of_type_named<SystemMonitor::ProcessStateWidget>("process_state")->set_pid(pid);
     main_widget->find_descendant_of_type_named<SystemMonitor::ProcessFileDescriptorMapWidget>("open_files")->set_pid(pid);
@@ -587,13 +587,13 @@ ErrorOr<void> build_performance_tab(GUI::Widget& graphs_container)
             cpu_graph.set_value_format(0, {
                                               .graph_color_role = ColorRole::SyntaxPreprocessorStatement,
                                               .text_formatter = [](u64 value) {
-                                                  return DeprecatedString::formatted("Total: {}%", value);
+                                                  return ByteString::formatted("Total: {}%", value);
                                               },
                                           });
             cpu_graph.set_value_format(1, {
                                               .graph_color_role = ColorRole::SyntaxPreprocessorValue,
                                               .text_formatter = [](u64 value) {
-                                                  return DeprecatedString::formatted("Kernel: {}%", value);
+                                                  return ByteString::formatted("Kernel: {}%", value);
                                               },
                                           });
             cpu_graphs.append(cpu_graph);
@@ -613,19 +613,19 @@ ErrorOr<void> build_performance_tab(GUI::Widget& graphs_container)
     memory_graph.set_value_format(0, {
                                          .graph_color_role = ColorRole::SyntaxComment,
                                          .text_formatter = [](u64 bytes) {
-                                             return DeprecatedString::formatted("Committed: {}", human_readable_size(bytes));
+                                             return ByteString::formatted("Committed: {}", human_readable_size(bytes));
                                          },
                                      });
     memory_graph.set_value_format(1, {
                                          .graph_color_role = ColorRole::SyntaxPreprocessorStatement,
                                          .text_formatter = [](u64 bytes) {
-                                             return DeprecatedString::formatted("Allocated: {}", human_readable_size(bytes));
+                                             return ByteString::formatted("Allocated: {}", human_readable_size(bytes));
                                          },
                                      });
     memory_graph.set_value_format(2, {
                                          .graph_color_role = ColorRole::SyntaxPreprocessorValue,
                                          .text_formatter = [](u64 bytes) {
-                                             return DeprecatedString::formatted("Kernel heap: {}", human_readable_size(bytes));
+                                             return ByteString::formatted("Kernel heap: {}", human_readable_size(bytes));
                                          },
                                      });
     return {};
diff --git a/Userland/Applications/Terminal/main.cpp b/Userland/Applications/Terminal/main.cpp
index e3431431623..58b7f947c70 100644
--- a/Userland/Applications/Terminal/main.cpp
+++ b/Userland/Applications/Terminal/main.cpp
@@ -139,7 +139,7 @@ static ErrorOr<void> utmp_update(StringView tty, pid_t pid, bool create)
 
 static ErrorOr<void> run_command(StringView command, bool keep_open)
 {
-    auto shell = TRY(String::from_deprecated_string(TRY(Core::Account::self(Core::Account::Read::PasswdOnly)).shell()));
+    auto shell = TRY(String::from_byte_string(TRY(Core::Account::self(Core::Account::Read::PasswdOnly)).shell()));
     if (shell.is_empty())
         shell = "/bin/Shell"_string;
 
diff --git a/Userland/Applications/TerminalSettings/TerminalSettingsWidget.cpp b/Userland/Applications/TerminalSettings/TerminalSettingsWidget.cpp
index 13480df6423..bcfb6404c69 100644
--- a/Userland/Applications/TerminalSettings/TerminalSettingsWidget.cpp
+++ b/Userland/Applications/TerminalSettings/TerminalSettingsWidget.cpp
@@ -236,7 +236,7 @@ VT::TerminalWidget::BellMode TerminalSettingsMainWidget::parse_bell(StringView b
     VERIFY_NOT_REACHED();
 }
 
-DeprecatedString TerminalSettingsMainWidget::stringify_bell(VT::TerminalWidget::BellMode bell_mode)
+ByteString TerminalSettingsMainWidget::stringify_bell(VT::TerminalWidget::BellMode bell_mode)
 {
     if (bell_mode == VT::TerminalWidget::BellMode::AudibleBeep)
         return "AudibleBeep";
diff --git a/Userland/Applications/TerminalSettings/TerminalSettingsWidget.h b/Userland/Applications/TerminalSettings/TerminalSettingsWidget.h
index e752f72bf01..df0be97d1ce 100644
--- a/Userland/Applications/TerminalSettings/TerminalSettingsWidget.h
+++ b/Userland/Applications/TerminalSettings/TerminalSettingsWidget.h
@@ -27,7 +27,7 @@ private:
     void write_back_settings() const;
 
     static VT::TerminalWidget::BellMode parse_bell(StringView bell_string);
-    static DeprecatedString stringify_bell(VT::TerminalWidget::BellMode bell_mode);
+    static ByteString stringify_bell(VT::TerminalWidget::BellMode bell_mode);
 
     VT::TerminalWidget::BellMode m_bell_mode { VT::TerminalWidget::BellMode::Disabled };
     bool m_confirm_close { true };
@@ -51,7 +51,7 @@ private:
 
     RefPtr<Gfx::Font const> m_font;
     float m_opacity;
-    DeprecatedString m_color_scheme;
+    ByteString m_color_scheme;
     VT::CursorShape m_cursor_shape { VT::CursorShape::Block };
     bool m_cursor_is_blinking_set { true };
     size_t m_max_history_size;
@@ -59,7 +59,7 @@ private:
 
     RefPtr<Gfx::Font const> m_original_font;
     float m_original_opacity;
-    DeprecatedString m_original_color_scheme;
+    ByteString m_original_color_scheme;
     VT::CursorShape m_original_cursor_shape;
     bool m_original_cursor_is_blinking_set;
     size_t m_original_max_history_size;
diff --git a/Userland/Applications/TextEditor/MainWidget.cpp b/Userland/Applications/TextEditor/MainWidget.cpp
index b256d6662db..e6d0adeeee0 100644
--- a/Userland/Applications/TextEditor/MainWidget.cpp
+++ b/Userland/Applications/TextEditor/MainWidget.cpp
@@ -127,7 +127,7 @@ MainWidget::MainWidget()
             m_editor->insert_at_cursor_or_replace_selection(substitute);
         } else {
             GUI::MessageBox::show(window(),
-                DeprecatedString::formatted("Not found: \"{}\"", needle),
+                ByteString::formatted("Not found: \"{}\"", needle),
                 "Not found"sv,
                 GUI::MessageBox::Type::Information);
         }
@@ -152,7 +152,7 @@ MainWidget::MainWidget()
             }
         } else {
             GUI::MessageBox::show(window(),
-                DeprecatedString::formatted("Not found: \"{}\"", needle),
+                ByteString::formatted("Not found: \"{}\"", needle),
                 "Not found"sv,
                 GUI::MessageBox::Type::Information);
         }
@@ -346,7 +346,7 @@ WebView::OutOfProcessWebView& MainWidget::ensure_web_view()
         m_page_view = web_view_container.add<WebView::OutOfProcessWebView>();
         m_page_view->on_link_hover = [this](auto& url) {
             if (url.is_valid())
-                m_statusbar->set_text(String::from_deprecated_string(url.to_deprecated_string()).release_value_but_fixme_should_propagate_errors());
+                m_statusbar->set_text(String::from_byte_string(url.to_byte_string()).release_value_but_fixme_should_propagate_errors());
             else
                 update_statusbar();
         };
@@ -354,7 +354,7 @@ WebView::OutOfProcessWebView& MainWidget::ensure_web_view()
             if (!Desktop::Launcher::open(url)) {
                 GUI::MessageBox::show(
                     window(),
-                    DeprecatedString::formatted("The link to '{}' could not be opened.", url),
+                    ByteString::formatted("The link to '{}' could not be opened.", url),
                     "Failed to open link"sv,
                     GUI::MessageBox::Type::Error);
             }
@@ -791,7 +791,7 @@ void MainWidget::update_title()
     else
         builder.append(m_path);
     builder.append("[*] - Text Editor"sv);
-    window()->set_title(builder.to_deprecated_string());
+    window()->set_title(builder.to_byte_string());
 }
 
 ErrorOr<void> MainWidget::read_file(String const& filename, Core::File& file)
@@ -803,7 +803,7 @@ ErrorOr<void> MainWidget::read_file(String const& filename, Core::File& file)
     return {};
 }
 
-void MainWidget::open_nonexistent_file(DeprecatedString const& path)
+void MainWidget::open_nonexistent_file(ByteString const& path)
 {
     m_editor->set_text({});
     set_path(path);
@@ -928,11 +928,11 @@ void MainWidget::update_statusbar()
 
     StringBuilder builder;
     if (m_editor->has_selection()) {
-        DeprecatedString selected_text = m_editor->selected_text();
+        ByteString selected_text = m_editor->selected_text();
         auto word_count = m_editor->number_of_selected_words();
         builder.appendff("{:'d} {} ({:'d} {}) selected", selected_text.length(), selected_text.length() == 1 ? "character" : "characters", word_count, word_count != 1 ? "words" : "word");
     } else {
-        DeprecatedString text = m_editor->text();
+        ByteString text = m_editor->text();
         auto word_count = m_editor->number_of_words();
         builder.appendff("{:'d} {} ({:'d} {})", text.length(), text.length() == 1 ? "character" : "characters", word_count, word_count != 1 ? "words" : "word");
     }
@@ -959,7 +959,7 @@ void MainWidget::find_text(GUI::TextEditor::SearchDirection direction, ShowMessa
 
     if (!result.is_valid() && show_message == ShowMessageIfNoResults::Yes) {
         GUI::MessageBox::show(window(),
-            DeprecatedString::formatted("Not found: \"{}\"", needle),
+            ByteString::formatted("Not found: \"{}\"", needle),
             "Not found"sv,
             GUI::MessageBox::Type::Information);
     }
diff --git a/Userland/Applications/TextEditor/MainWidget.h b/Userland/Applications/TextEditor/MainWidget.h
index 0e338d7e925..38c8b5c265d 100644
--- a/Userland/Applications/TextEditor/MainWidget.h
+++ b/Userland/Applications/TextEditor/MainWidget.h
@@ -26,7 +26,7 @@ class MainWidget final : public GUI::Widget {
 public:
     virtual ~MainWidget() override = default;
     ErrorOr<void> read_file(String const& filename, Core::File&);
-    void open_nonexistent_file(DeprecatedString const& path);
+    void open_nonexistent_file(ByteString const& path);
     bool request_close();
 
     GUI::TextEditor& editor() { return *m_editor; }
@@ -64,9 +64,9 @@ private:
     void find_text(GUI::TextEditor::SearchDirection, ShowMessageIfNoResults);
 
     RefPtr<GUI::TextEditor> m_editor;
-    DeprecatedString m_path;
-    DeprecatedString m_name;
-    DeprecatedString m_extension;
+    ByteString m_path;
+    ByteString m_name;
+    ByteString m_extension;
     RefPtr<GUI::Action> m_new_action;
     RefPtr<GUI::Action> m_open_action;
     RefPtr<GUI::Action> m_save_action;
diff --git a/Userland/Applications/TextEditor/main.cpp b/Userland/Applications/TextEditor/main.cpp
index b2a491d7f07..a57a08e5248 100644
--- a/Userland/Applications/TextEditor/main.cpp
+++ b/Userland/Applications/TextEditor/main.cpp
@@ -79,11 +79,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         FileArgument parsed_argument(filename);
 
         FileSystemAccessClient::Client::the().set_silence_errors(FileSystemAccessClient::ErrorFlag::NoEntries);
-        auto response = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, parsed_argument.filename().to_deprecated_string());
+        auto response = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, parsed_argument.filename().to_byte_string());
 
         if (response.is_error()) {
             if (response.error().code() == ENOENT)
-                text_widget->open_nonexistent_file(parsed_argument.filename().to_deprecated_string());
+                text_widget->open_nonexistent_file(parsed_argument.filename().to_byte_string());
         } else {
             TRY(text_widget->read_file(response.value().filename(), response.value().stream()));
             text_widget->editor().set_cursor_and_focus_line(parsed_argument.line().value_or(1) - 1, parsed_argument.column().value_or(0));
diff --git a/Userland/Applications/ThemeEditor/MainWidget.cpp b/Userland/Applications/ThemeEditor/MainWidget.cpp
index 3743fa8484b..ea40d5ad933 100644
--- a/Userland/Applications/ThemeEditor/MainWidget.cpp
+++ b/Userland/Applications/ThemeEditor/MainWidget.cpp
@@ -259,7 +259,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
             return;
         auto load_from_file_result = load_from_file(response.value().filename(), response.value().release_stream());
         if (load_from_file_result.is_error()) {
-            GUI::MessageBox::show_error(&window, DeprecatedString::formatted("Can't open file named {}: {}", response.value().filename(), load_from_file_result.error()));
+            GUI::MessageBox::show_error(&window, ByteString::formatted("Can't open file named {}: {}", response.value().filename(), load_from_file_result.error()));
             return;
         }
     }));
@@ -295,7 +295,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
             return;
         auto load_from_file_result = load_from_file(response.value().filename(), response.value().release_stream());
         if (load_from_file_result.is_error()) {
-            GUI::MessageBox::show_error(&window, DeprecatedString::formatted("Can't open file named {}: {}", response.value().filename(), load_from_file_result.error()));
+            GUI::MessageBox::show_error(&window, ByteString::formatted("Can't open file named {}: {}", response.value().filename(), load_from_file_result.error()));
             return;
         }
     });
@@ -316,7 +316,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
 
 void MainWidget::update_title()
 {
-    window()->set_title(DeprecatedString::formatted("{}[*] - Theme Editor", m_path.value_or("Untitled")));
+    window()->set_title(ByteString::formatted("{}[*] - Theme Editor", m_path.value_or("Untitled")));
 }
 
 GUI::Window::CloseRequestDecision MainWidget::request_close()
@@ -338,7 +338,7 @@ GUI::Window::CloseRequestDecision MainWidget::request_close()
     return GUI::Window::CloseRequestDecision::StayOpen;
 }
 
-void MainWidget::set_path(DeprecatedString path)
+void MainWidget::set_path(ByteString path)
 {
     m_path = path;
     update_title();
@@ -346,13 +346,13 @@ void MainWidget::set_path(DeprecatedString path)
 
 void MainWidget::save_to_file(String const& filename, NonnullOwnPtr<Core::File> file)
 {
-    auto theme = Core::ConfigFile::open(filename.to_deprecated_string(), move(file)).release_value_but_fixme_should_propagate_errors();
+    auto theme = Core::ConfigFile::open(filename.to_byte_string(), move(file)).release_value_but_fixme_should_propagate_errors();
 
 #define __ENUMERATE_ALIGNMENT_ROLE(role) theme->write_entry("Alignments", to_string(Gfx::AlignmentRole::role), to_string(m_current_palette.alignment(Gfx::AlignmentRole::role)));
     ENUMERATE_ALIGNMENT_ROLES(__ENUMERATE_ALIGNMENT_ROLE)
 #undef __ENUMERATE_ALIGNMENT_ROLE
 
-#define __ENUMERATE_COLOR_ROLE(role) theme->write_entry("Colors", to_string(Gfx::ColorRole::role), m_current_palette.color(Gfx::ColorRole::role).to_deprecated_string());
+#define __ENUMERATE_COLOR_ROLE(role) theme->write_entry("Colors", to_string(Gfx::ColorRole::role), m_current_palette.color(Gfx::ColorRole::role).to_byte_string());
     ENUMERATE_COLOR_ROLES(__ENUMERATE_COLOR_ROLE)
 #undef __ENUMERATE_COLOR_ROLE
 
@@ -370,10 +370,10 @@ void MainWidget::save_to_file(String const& filename, NonnullOwnPtr<Core::File>
 
     auto sync_result = theme->sync();
     if (sync_result.is_error()) {
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to save theme file: {}", sync_result.error()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to save theme file: {}", sync_result.error()));
     } else {
         m_last_modified_time = MonotonicTime::now();
-        set_path(filename.to_deprecated_string());
+        set_path(filename.to_byte_string());
         window()->set_modified(false);
         GUI::Application::the()->set_most_recently_open_file(filename);
     }
@@ -597,7 +597,7 @@ void MainWidget::set_metric(Gfx::MetricRole role, int value)
     set_palette(preview_palette);
 }
 
-void MainWidget::set_path(Gfx::PathRole role, DeprecatedString value)
+void MainWidget::set_path(Gfx::PathRole role, ByteString value)
 {
     auto preview_palette = m_current_palette;
     preview_palette.set_path(role, value);
@@ -615,7 +615,7 @@ void MainWidget::set_palette(Gfx::Palette palette)
 void MainWidget::show_path_picker_dialog(StringView property_display_name, GUI::TextBox& path_input, PathPickerTarget path_picker_target)
 {
     bool open_folder = path_picker_target == PathPickerTarget::Folder;
-    auto window_title = DeprecatedString::formatted(open_folder ? "Select {} folder"sv : "Select {} file"sv, property_display_name);
+    auto window_title = ByteString::formatted(open_folder ? "Select {} folder"sv : "Select {} file"sv, property_display_name);
     auto target_path = path_input.text();
     if (FileSystem::exists(target_path)) {
         if (!FileSystem::is_directory(target_path))
@@ -631,13 +631,13 @@ void MainWidget::show_path_picker_dialog(StringView property_display_name, GUI::
 
 ErrorOr<void> MainWidget::load_from_file(String const& filename, NonnullOwnPtr<Core::File> file)
 {
-    auto config_file = TRY(Core::ConfigFile::open(filename.to_deprecated_string(), move(file)));
+    auto config_file = TRY(Core::ConfigFile::open(filename.to_byte_string(), move(file)));
     auto theme = TRY(Gfx::load_system_theme(config_file));
     VERIFY(theme.is_valid());
 
     auto new_palette = Gfx::Palette(Gfx::PaletteImpl::create_with_anonymous_buffer(theme));
     set_palette(move(new_palette));
-    set_path(filename.to_deprecated_string());
+    set_path(filename.to_byte_string());
 
 #define __ENUMERATE_ALIGNMENT_ROLE(role)                                                    \
     if (auto alignment_input = m_alignment_inputs[to_underlying(Gfx::AlignmentRole::role)]) \
@@ -704,7 +704,7 @@ void MainWidget::drop_event(GUI::DropEvent& event)
 
         auto load_from_file_result = load_from_file(response.value().filename(), response.value().release_stream());
         if (load_from_file_result.is_error())
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Can't open file named {}: {}", response.value().filename(), load_from_file_result.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Can't open file named {}: {}", response.value().filename(), load_from_file_result.error()));
     }
 }
 
diff --git a/Userland/Applications/ThemeEditor/MainWidget.h b/Userland/Applications/ThemeEditor/MainWidget.h
index e86c946d45f..b394fe8d619 100644
--- a/Userland/Applications/ThemeEditor/MainWidget.h
+++ b/Userland/Applications/ThemeEditor/MainWidget.h
@@ -52,7 +52,7 @@ private:
     AlignmentModel() = default;
 
     struct AlignmentValue {
-        DeprecatedString title;
+        ByteString title;
         Gfx::TextAlignment setting_value;
     };
     Vector<AlignmentValue> m_alignments {
@@ -67,7 +67,7 @@ struct Property {
 };
 
 struct PropertyGroup {
-    DeprecatedString title;
+    ByteString title;
     Vector<Property> properties;
 };
 
@@ -96,7 +96,7 @@ private:
 
     void save_to_file(String const& filename, NonnullOwnPtr<Core::File> file);
     ErrorOr<Core::AnonymousBuffer> encode();
-    void set_path(DeprecatedString);
+    void set_path(ByteString);
 
     void build_override_controls();
 
@@ -105,7 +105,7 @@ private:
     void set_color(Gfx::ColorRole, Gfx::Color);
     void set_flag(Gfx::FlagRole, bool);
     void set_metric(Gfx::MetricRole, int);
-    void set_path(Gfx::PathRole, DeprecatedString);
+    void set_path(Gfx::PathRole, ByteString);
 
     void set_palette(Gfx::Palette);
 
@@ -123,7 +123,7 @@ private:
     RefPtr<GUI::Button> m_theme_override_apply;
     RefPtr<GUI::Button> m_theme_override_reset;
 
-    Optional<DeprecatedString> m_path;
+    Optional<ByteString> m_path;
     Gfx::Palette m_current_palette;
     MonotonicTime m_last_modified_time { MonotonicTime::now() };
 
diff --git a/Userland/Applications/ThemeEditor/main.cpp b/Userland/Applications/ThemeEditor/main.cpp
index facff62fc7a..abaec1a6df4 100644
--- a/Userland/Applications/ThemeEditor/main.cpp
+++ b/Userland/Applications/ThemeEditor/main.cpp
@@ -57,11 +57,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         // Note: This is deferred to ensure that the window has already popped and any error dialog boxes would show up correctly.
         app->event_loop().deferred_invoke(
             [&window, &path, &main_widget]() {
-                auto response = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, path.value().to_deprecated_string());
+                auto response = FileSystemAccessClient::Client::the().request_file_read_only_approved(window, path.value().to_byte_string());
                 if (!response.is_error()) {
                     auto load_from_file_result = main_widget->load_from_file(response.value().filename(), response.value().release_stream());
                     if (load_from_file_result.is_error())
-                        GUI::MessageBox::show_error(window, DeprecatedString::formatted("Loading theme from file has failed: {}", load_from_file_result.error()));
+                        GUI::MessageBox::show_error(window, ByteString::formatted("Loading theme from file has failed: {}", load_from_file_result.error()));
                 }
             });
     }
diff --git a/Userland/Applications/VideoPlayer/VideoPlayerWidget.cpp b/Userland/Applications/VideoPlayer/VideoPlayerWidget.cpp
index 4cf4d423997..7862fbed189 100644
--- a/Userland/Applications/VideoPlayer/VideoPlayerWidget.cpp
+++ b/Userland/Applications/VideoPlayer/VideoPlayerWidget.cpp
@@ -237,7 +237,7 @@ void VideoPlayerWidget::on_decoding_error(Video::DecoderError const& error)
         break;
     }
 
-    GUI::MessageBox::show(window(), DeprecatedString::formatted(text_format, error.string_literal()), "Video Player encountered an error"sv);
+    GUI::MessageBox::show(window(), ByteString::formatted(text_format, error.string_literal()), "Video Player encountered an error"sv);
 }
 
 void VideoPlayerWidget::update_seek_slider_max()
@@ -352,7 +352,7 @@ void VideoPlayerWidget::update_title()
     }
 
     string_builder.append("[*] - Video Player"sv);
-    window()->set_title(string_builder.to_deprecated_string());
+    window()->set_title(string_builder.to_byte_string());
 }
 
 Video::PlaybackManager::SeekMode VideoPlayerWidget::seek_mode()
diff --git a/Userland/Applications/Welcome/WelcomeWidget.cpp b/Userland/Applications/Welcome/WelcomeWidget.cpp
index e7dd7372b92..cdb3d718b54 100644
--- a/Userland/Applications/Welcome/WelcomeWidget.cpp
+++ b/Userland/Applications/Welcome/WelcomeWidget.cpp
@@ -37,7 +37,7 @@ ErrorOr<void> WelcomeWidget::create_widgets()
     m_web_view = find_descendant_of_type_named<WebView::OutOfProcessWebView>("web_view");
     m_web_view->use_native_user_style_sheet();
     auto path = TRY(String::formatted("{}/README.md", Core::StandardPaths::home_directory()));
-    m_web_view->load(URL::create_with_file_scheme(path.to_deprecated_string()));
+    m_web_view->load(URL::create_with_file_scheme(path.to_byte_string()));
 
     m_tip_label = find_descendant_of_type_named<GUI::Label>("tip_label");
     m_tip_frame = find_descendant_of_type_named<GUI::Frame>("tip_frame");
diff --git a/Userland/Demos/Mandelbrot/Mandelbrot.cpp b/Userland/Demos/Mandelbrot/Mandelbrot.cpp
index 7b1f88473ee..0c03720e46b 100644
--- a/Userland/Demos/Mandelbrot/Mandelbrot.cpp
+++ b/Userland/Demos/Mandelbrot/Mandelbrot.cpp
@@ -217,7 +217,7 @@ enum class ImageType {
 class Mandelbrot : public GUI::Frame {
     C_OBJECT(Mandelbrot)
 
-    ErrorOr<void> export_image(DeprecatedString const& export_path, ImageType image_type);
+    ErrorOr<void> export_image(ByteString const& export_path, ImageType image_type);
 
     enum class Zoom {
         In,
@@ -366,7 +366,7 @@ void Mandelbrot::resize_event(GUI::ResizeEvent& event)
     m_set.resize(event.size());
 }
 
-ErrorOr<void> Mandelbrot::export_image(DeprecatedString const& export_path, ImageType image_type)
+ErrorOr<void> Mandelbrot::export_image(ByteString const& export_path, ImageType image_type)
 {
     m_set.resize(Gfx::IntSize { 1920, 1080 });
     ByteBuffer encoded_data;
@@ -386,7 +386,7 @@ ErrorOr<void> Mandelbrot::export_image(DeprecatedString const& export_path, Imag
     m_set.resize(size());
     auto file = fopen(export_path.characters(), "wb");
     if (!file) {
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("Could not open '{}' for writing.", export_path), "Mandelbrot"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(window(), ByteString::formatted("Could not open '{}' for writing.", export_path), "Mandelbrot"sv, GUI::MessageBox::Type::Error);
         return {};
     }
     fwrite(encoded_data.data(), 1, encoded_data.size(), file);
@@ -419,27 +419,27 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     export_submenu->add_action(GUI::Action::create("As &BMP...",
         [&](GUI::Action&) {
-            Optional<DeprecatedString> export_path = GUI::FilePicker::get_save_filepath(window, "untitled", "bmp");
+            Optional<ByteString> export_path = GUI::FilePicker::get_save_filepath(window, "untitled", "bmp");
             if (!export_path.has_value())
                 return;
             if (auto result = mandelbrot->export_image(export_path.value(), ImageType::BMP); result.is_error())
-                GUI::MessageBox::show_error(window, DeprecatedString::formatted("{}", result.error()));
+                GUI::MessageBox::show_error(window, ByteString::formatted("{}", result.error()));
         }));
     export_submenu->add_action(GUI::Action::create("As &PNG...", { Mod_Ctrl | Mod_Shift, Key_S },
         [&](GUI::Action&) {
-            Optional<DeprecatedString> export_path = GUI::FilePicker::get_save_filepath(window, "untitled", "png");
+            Optional<ByteString> export_path = GUI::FilePicker::get_save_filepath(window, "untitled", "png");
             if (!export_path.has_value())
                 return;
             if (auto result = mandelbrot->export_image(export_path.value(), ImageType::PNG); result.is_error())
-                GUI::MessageBox::show_error(window, DeprecatedString::formatted("{}", result.error()));
+                GUI::MessageBox::show_error(window, ByteString::formatted("{}", result.error()));
         }));
     export_submenu->add_action(GUI::Action::create("As &QOI...",
         [&](GUI::Action&) {
-            Optional<DeprecatedString> export_path = GUI::FilePicker::get_save_filepath(window, "untitled", "qoi");
+            Optional<ByteString> export_path = GUI::FilePicker::get_save_filepath(window, "untitled", "qoi");
             if (!export_path.has_value())
                 return;
             if (auto result = mandelbrot->export_image(export_path.value(), ImageType::QOI); result.is_error())
-                GUI::MessageBox::show_error(window, DeprecatedString::formatted("{}", result.error()));
+                GUI::MessageBox::show_error(window, ByteString::formatted("{}", result.error()));
         }));
 
     export_submenu->set_icon(TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/save.png"sv)));
diff --git a/Userland/Demos/ModelGallery/BasicModel.cpp b/Userland/Demos/ModelGallery/BasicModel.cpp
index fe70c7133fb..10645907f61 100644
--- a/Userland/Demos/ModelGallery/BasicModel.cpp
+++ b/Userland/Demos/ModelGallery/BasicModel.cpp
@@ -50,7 +50,7 @@ GUI::ModelIndex BasicModel::index(int row, int column, GUI::ModelIndex const& pa
     return create_index(row, column);
 }
 
-void BasicModel::add_item(DeprecatedString const& item)
+void BasicModel::add_item(ByteString const& item)
 {
     begin_insert_rows({}, m_items.size(), m_items.size());
     m_items.append(item);
diff --git a/Userland/Demos/ModelGallery/BasicModel.h b/Userland/Demos/ModelGallery/BasicModel.h
index 6fdd896b24d..5b059d27560 100644
--- a/Userland/Demos/ModelGallery/BasicModel.h
+++ b/Userland/Demos/ModelGallery/BasicModel.h
@@ -29,7 +29,7 @@ public:
 
     Function<void()> on_invalidate;
 
-    void add_item(DeprecatedString const& item);
+    void add_item(ByteString const& item);
     void remove_item(GUI::ModelIndex const&);
 
 private:
@@ -37,5 +37,5 @@ private:
     {
     }
 
-    Vector<DeprecatedString> m_items;
+    Vector<ByteString> m_items;
 };
diff --git a/Userland/Demos/WidgetGallery/DemoWizardDialog.h b/Userland/Demos/WidgetGallery/DemoWizardDialog.h
index daaa86faaa7..cb7ca08563b 100644
--- a/Userland/Demos/WidgetGallery/DemoWizardDialog.h
+++ b/Userland/Demos/WidgetGallery/DemoWizardDialog.h
@@ -17,7 +17,7 @@ class DemoWizardDialog : public GUI::WizardDialog {
     C_OBJECT(DemoWizardDialog);
 
 public:
-    DeprecatedString page_1_location() { return m_page_1_location_text_box->get_text(); }
+    ByteString page_1_location() { return m_page_1_location_text_box->get_text(); }
 
 private:
     DemoWizardDialog(GUI::Window* parent_window);
diff --git a/Userland/Demos/WidgetGallery/GalleryModels.h b/Userland/Demos/WidgetGallery/GalleryModels.h
index 20d4d403a34..0d14c47034e 100644
--- a/Userland/Demos/WidgetGallery/GalleryModels.h
+++ b/Userland/Demos/WidgetGallery/GalleryModels.h
@@ -60,7 +60,7 @@ public:
     {
         m_cursors.clear();
 
-        Core::DirIterator iterator(DeprecatedString::formatted("/res/cursor-themes/{}", GUI::ConnectionToWindowServer::the().get_cursor_theme()), Core::DirIterator::Flags::SkipDots);
+        Core::DirIterator iterator(ByteString::formatted("/res/cursor-themes/{}", GUI::ConnectionToWindowServer::the().get_cursor_theme()), Core::DirIterator::Flags::SkipDots);
 
         while (iterator.has_next()) {
             auto path = iterator.next_full_path();
@@ -90,8 +90,8 @@ private:
 
     struct Cursor {
         RefPtr<Gfx::Bitmap> bitmap;
-        DeprecatedString path;
-        DeprecatedString name;
+        ByteString path;
+        ByteString name;
         Gfx::CursorParams params;
     };
 
@@ -194,7 +194,7 @@ private:
     struct IconSet {
         RefPtr<Gfx::Bitmap> big_icon;
         RefPtr<Gfx::Bitmap> little_icon;
-        DeprecatedString name;
+        ByteString name;
     };
 
     Vector<IconSet> m_icon_sets;
diff --git a/Userland/Demos/WidgetGallery/GalleryWidget.cpp b/Userland/Demos/WidgetGallery/GalleryWidget.cpp
index dc19983d6fa..edc9b9a9977 100644
--- a/Userland/Demos/WidgetGallery/GalleryWidget.cpp
+++ b/Userland/Demos/WidgetGallery/GalleryWidget.cpp
@@ -53,7 +53,7 @@ GalleryWidget::GalleryWidget()
     m_frame_shapes.append("Sunken Panel");
 
     m_frame_shape_combobox = basics_tab.find_descendant_of_type_named<GUI::ComboBox>("frame_style_combobox");
-    m_frame_shape_combobox->set_model(*GUI::ItemListModel<DeprecatedString>::create(m_frame_shapes));
+    m_frame_shape_combobox->set_model(*GUI::ItemListModel<ByteString>::create(m_frame_shapes));
 
     m_frame_shape_combobox->on_change = [&](auto&, auto const& index) {
         m_label_frame->set_frame_style(static_cast<Gfx::FrameStyle>(index.row()));
@@ -61,7 +61,7 @@ GalleryWidget::GalleryWidget()
     };
 
     m_frame_shape_combobox->on_return_pressed = [&]() {
-        m_enabled_label->set_text(String::from_deprecated_string(m_frame_shape_combobox->text()).release_value_but_fixme_should_propagate_errors());
+        m_enabled_label->set_text(String::from_byte_string(m_frame_shape_combobox->text()).release_value_but_fixme_should_propagate_errors());
     };
 
     m_button_icons.append(Gfx::Bitmap::load_from_file("/res/icons/16x16/book-open.png"sv).release_value_but_fixme_should_propagate_errors());
@@ -141,7 +141,7 @@ GalleryWidget::GalleryWidget()
     m_msgbox_buttons.append("Yes No Cancel");
 
     m_msgbox_icon_combobox = basics_tab.find_descendant_of_type_named<GUI::ComboBox>("msgbox_icon_combobox");
-    m_msgbox_icon_combobox->set_model(*GUI::ItemListModel<DeprecatedString>::create(m_msgbox_icons));
+    m_msgbox_icon_combobox->set_model(*GUI::ItemListModel<ByteString>::create(m_msgbox_icons));
     m_msgbox_icon_combobox->set_selected_index(0);
 
     m_msgbox_icon_combobox->on_change = [&](auto&, auto const& index) {
@@ -149,7 +149,7 @@ GalleryWidget::GalleryWidget()
     };
 
     m_msgbox_buttons_combobox = basics_tab.find_descendant_of_type_named<GUI::ComboBox>("msgbox_buttons_combobox");
-    m_msgbox_buttons_combobox->set_model(*GUI::ItemListModel<DeprecatedString>::create(m_msgbox_buttons));
+    m_msgbox_buttons_combobox->set_model(*GUI::ItemListModel<ByteString>::create(m_msgbox_buttons));
     m_msgbox_buttons_combobox->set_selected_index(0);
 
     m_msgbox_buttons_combobox->on_change = [&](auto&, auto const& index) {
@@ -260,20 +260,20 @@ GalleryWidget::GalleryWidget()
         " _||_-\n"
     };
 
-    m_wizard_output->set_text(DeprecatedString::formatted("{}{}", serenityos_ascii, wizard_ascii));
+    m_wizard_output->set_text(ByteString::formatted("{}{}", serenityos_ascii, wizard_ascii));
 
     m_wizard_button->on_click = [&](auto) {
         StringBuilder sb;
         sb.append(m_wizard_output->get_text());
         sb.append("\nWizard started."sv);
-        m_wizard_output->set_text(sb.to_deprecated_string());
+        m_wizard_output->set_text(sb.to_byte_string());
 
         auto wizard = DemoWizardDialog::try_create(window()).release_value_but_fixme_should_propagate_errors();
         auto result = wizard->exec();
 
-        sb.append(DeprecatedString::formatted("\nWizard execution complete.\nDialog ExecResult code: {}", to_underlying(result)));
+        sb.append(ByteString::formatted("\nWizard execution complete.\nDialog ExecResult code: {}", to_underlying(result)));
         if (result == GUI::Dialog::ExecResult::OK)
-            sb.append(DeprecatedString::formatted(" (ExecResult::OK)\n'Installation' location: \"{}\"", wizard->page_1_location()));
+            sb.append(ByteString::formatted(" (ExecResult::OK)\n'Installation' location: \"{}\"", wizard->page_1_location()));
         m_wizard_output->set_text(sb.string_view());
     };
 
diff --git a/Userland/Demos/WidgetGallery/GalleryWidget.h b/Userland/Demos/WidgetGallery/GalleryWidget.h
index 89322d0ab05..d94c9f1d9c5 100644
--- a/Userland/Demos/WidgetGallery/GalleryWidget.h
+++ b/Userland/Demos/WidgetGallery/GalleryWidget.h
@@ -61,9 +61,9 @@ private:
     RefPtr<GUI::ValueSlider> m_opacity_value_slider;
     RefPtr<GUI::ImageWidget> m_opacity_imagewidget;
 
-    Vector<DeprecatedString> m_frame_shapes;
-    Vector<DeprecatedString> m_msgbox_icons;
-    Vector<DeprecatedString> m_msgbox_buttons;
+    Vector<ByteString> m_frame_shapes;
+    Vector<ByteString> m_msgbox_icons;
+    Vector<ByteString> m_msgbox_buttons;
     Vector<RefPtr<Gfx::Bitmap>> m_button_icons;
 
     GUI::MessageBox::Type m_msgbox_type;
diff --git a/Userland/DevTools/GMLPlayground/MainWidget.cpp b/Userland/DevTools/GMLPlayground/MainWidget.cpp
index 5645008ada8..19fb338ff09 100644
--- a/Userland/DevTools/GMLPlayground/MainWidget.cpp
+++ b/Userland/DevTools/GMLPlayground/MainWidget.cpp
@@ -36,19 +36,19 @@ class UnregisteredWidget final : public GUI::Widget {
     C_OBJECT(UnregisteredWidget);
 
 private:
-    UnregisteredWidget(DeprecatedString const& class_name);
+    UnregisteredWidget(ByteString const& class_name);
 
     virtual void paint_event(GUI::PaintEvent& event) override;
 
-    DeprecatedString m_text;
+    ByteString m_text;
 };
 
-UnregisteredWidget::UnregisteredWidget(DeprecatedString const& class_name)
+UnregisteredWidget::UnregisteredWidget(ByteString const& class_name)
 {
     StringBuilder builder;
     builder.append(class_name);
     builder.append("\nnot registered"sv);
-    m_text = builder.to_deprecated_string();
+    m_text = builder.to_byte_string();
 }
 
 void UnregisteredWidget::paint_event(GUI::PaintEvent& event)
@@ -114,7 +114,7 @@ MainWidget::MainWidget()
 
 void MainWidget::update_title()
 {
-    window()->set_title(DeprecatedString::formatted("{}[*] - GML Playground", m_file_path.is_empty() ? "Untitled"sv : m_file_path.view()));
+    window()->set_title(ByteString::formatted("{}[*] - GML Playground", m_file_path.is_empty() ? "Untitled"sv : m_file_path.view()));
 }
 
 void MainWidget::load_file(FileSystemAccessClient::File file)
@@ -126,7 +126,7 @@ void MainWidget::load_file(FileSystemAccessClient::File file)
     m_editor->set_text(buffer_or_error.release_value());
     m_editor->set_focus(true);
 
-    m_file_path = file.filename().to_deprecated_string();
+    m_file_path = file.filename().to_byte_string();
     update_title();
 
     GUI::Application::the()->set_most_recently_open_file(file.filename());
@@ -144,10 +144,10 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
 
         auto file = response.value().release_stream();
         if (auto result = m_editor->write_to_file(*file); result.is_error()) {
-            GUI::MessageBox::show(&window, DeprecatedString::formatted("Unable to save file: {}\n"sv, result.release_error()), "Error"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(&window, ByteString::formatted("Unable to save file: {}\n"sv, result.release_error()), "Error"sv, GUI::MessageBox::Type::Error);
             return;
         }
-        m_file_path = response.value().filename().to_deprecated_string();
+        m_file_path = response.value().filename().to_byte_string();
         update_title();
 
         GUI::Application::the()->set_most_recently_open_file(response.value().filename());
@@ -164,7 +164,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
 
         auto file = response.value().release_stream();
         if (auto result = m_editor->write_to_file(*file); result.is_error()) {
-            GUI::MessageBox::show(&window, DeprecatedString::formatted("Unable to save file: {}\n"sv, result.release_error()), "Error"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(&window, ByteString::formatted("Unable to save file: {}\n"sv, result.release_error()), "Error"sv, GUI::MessageBox::Type::Error);
             return;
         }
         update_title();
@@ -225,7 +225,7 @@ ErrorOr<void> MainWidget::initialize_menubar(GUI::Window& window)
         } else {
             GUI::MessageBox::show(
                 &window,
-                DeprecatedString::formatted("GML could not be formatted: {}", formatted_gml_or_error.error()),
+                ByteString::formatted("GML could not be formatted: {}", formatted_gml_or_error.error()),
                 "Error"sv,
                 GUI::MessageBox::Type::Error);
         }
diff --git a/Userland/DevTools/GMLPlayground/MainWidget.h b/Userland/DevTools/GMLPlayground/MainWidget.h
index a333855101b..7d2bb4df5da 100644
--- a/Userland/DevTools/GMLPlayground/MainWidget.h
+++ b/Userland/DevTools/GMLPlayground/MainWidget.h
@@ -51,5 +51,5 @@ private:
     RefPtr<GUI::Action> m_view_window_action;
 
     GUI::Icon m_icon;
-    DeprecatedString m_file_path;
+    ByteString m_file_path;
 };
diff --git a/Userland/DevTools/HackStudio/AutoCompleteResponse.h b/Userland/DevTools/HackStudio/AutoCompleteResponse.h
index 216d040f79d..ca4cb4c8f97 100644
--- a/Userland/DevTools/HackStudio/AutoCompleteResponse.h
+++ b/Userland/DevTools/HackStudio/AutoCompleteResponse.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Types.h>
 #include <LibCpp/Parser.h>
 #include <LibGUI/AutocompleteProvider.h>
@@ -29,10 +29,10 @@ inline ErrorOr<void> encode(Encoder& encoder, CodeComprehension::AutocompleteRes
 template<>
 inline ErrorOr<CodeComprehension::AutocompleteResultEntry> decode(Decoder& decoder)
 {
-    auto completion = TRY(decoder.decode<DeprecatedString>());
+    auto completion = TRY(decoder.decode<ByteString>());
     auto partial_input_length = TRY(decoder.decode<size_t>());
     auto language = TRY(decoder.decode<CodeComprehension::Language>());
-    auto display_text = TRY(decoder.decode<DeprecatedString>());
+    auto display_text = TRY(decoder.decode<ByteString>());
     auto hide_autocomplete_after_applying = TRY(decoder.decode<CodeComprehension::AutocompleteResultEntry::HideAutocompleteAfterApplying>());
 
     return CodeComprehension::AutocompleteResultEntry { move(completion), partial_input_length, language, move(display_text), hide_autocomplete_after_applying };
@@ -50,7 +50,7 @@ inline ErrorOr<void> encode(Encoder& encoder, CodeComprehension::ProjectLocation
 template<>
 inline ErrorOr<CodeComprehension::ProjectLocation> decode(Decoder& decoder)
 {
-    auto file = TRY(decoder.decode<DeprecatedString>());
+    auto file = TRY(decoder.decode<ByteString>());
     auto line = TRY(decoder.decode<size_t>());
     auto column = TRY(decoder.decode<size_t>());
 
@@ -70,10 +70,10 @@ inline ErrorOr<void> encode(Encoder& encoder, CodeComprehension::Declaration con
 template<>
 inline ErrorOr<CodeComprehension::Declaration> decode(Decoder& decoder)
 {
-    auto name = TRY(decoder.decode<DeprecatedString>());
+    auto name = TRY(decoder.decode<ByteString>());
     auto position = TRY(decoder.decode<CodeComprehension::ProjectLocation>());
     auto type = TRY(decoder.decode<CodeComprehension::DeclarationType>());
-    auto scope = TRY(decoder.decode<DeprecatedString>());
+    auto scope = TRY(decoder.decode<ByteString>());
 
     return CodeComprehension::Declaration { move(name), position, type, move(scope) };
 }
@@ -91,8 +91,8 @@ inline ErrorOr<void> encode(Encoder& encoder, CodeComprehension::TodoEntry const
 template<>
 inline ErrorOr<CodeComprehension::TodoEntry> decode(Decoder& decoder)
 {
-    auto content = TRY(decoder.decode<DeprecatedString>());
-    auto filename = TRY(decoder.decode<DeprecatedString>());
+    auto content = TRY(decoder.decode<ByteString>());
+    auto filename = TRY(decoder.decode<ByteString>());
     auto line = TRY(decoder.decode<size_t>());
     auto column = TRY(decoder.decode<size_t>());
 
diff --git a/Userland/DevTools/HackStudio/CodeDocument.cpp b/Userland/DevTools/HackStudio/CodeDocument.cpp
index c4caef00242..1cbec9969fe 100644
--- a/Userland/DevTools/HackStudio/CodeDocument.cpp
+++ b/Userland/DevTools/HackStudio/CodeDocument.cpp
@@ -9,7 +9,7 @@
 
 namespace HackStudio {
 
-NonnullRefPtr<CodeDocument> CodeDocument::create(DeprecatedString const& file_path, Client* client)
+NonnullRefPtr<CodeDocument> CodeDocument::create(ByteString const& file_path, Client* client)
 {
     return adopt_ref(*new CodeDocument(file_path, client));
 }
@@ -19,7 +19,7 @@ NonnullRefPtr<CodeDocument> CodeDocument::create(Client* client)
     return adopt_ref(*new CodeDocument(client));
 }
 
-CodeDocument::CodeDocument(DeprecatedString const& file_path, Client* client)
+CodeDocument::CodeDocument(ByteString const& file_path, Client* client)
     : TextDocument(client)
     , m_file_path(file_path)
 {
diff --git a/Userland/DevTools/HackStudio/CodeDocument.h b/Userland/DevTools/HackStudio/CodeDocument.h
index 045d3a5d82d..e9004811e11 100644
--- a/Userland/DevTools/HackStudio/CodeDocument.h
+++ b/Userland/DevTools/HackStudio/CodeDocument.h
@@ -18,7 +18,7 @@ class Editor;
 class CodeDocument final : public GUI::TextDocument {
 public:
     virtual ~CodeDocument() override = default;
-    static NonnullRefPtr<CodeDocument> create(DeprecatedString const& file_path, Client* client = nullptr);
+    static NonnullRefPtr<CodeDocument> create(ByteString const& file_path, Client* client = nullptr);
     static NonnullRefPtr<CodeDocument> create(Client* client = nullptr);
 
     Vector<size_t> const& breakpoint_lines() const { return m_breakpoint_lines; }
@@ -26,7 +26,7 @@ public:
     Optional<size_t> execution_position() const { return m_execution_position; }
     void set_execution_position(size_t line) { m_execution_position = line; }
     void clear_execution_position() { m_execution_position.clear(); }
-    DeprecatedString const& file_path() const { return m_file_path; }
+    ByteString const& file_path() const { return m_file_path; }
     Optional<Syntax::Language> const& language() const { return m_language; }
 
     enum class DiffType {
@@ -39,10 +39,10 @@ public:
     void set_line_differences(Badge<Editor>, Vector<DiffType>);
 
 private:
-    explicit CodeDocument(DeprecatedString const& file_path, Client* client = nullptr);
+    explicit CodeDocument(ByteString const& file_path, Client* client = nullptr);
     explicit CodeDocument(Client* client = nullptr);
 
-    DeprecatedString m_file_path;
+    ByteString m_file_path;
     Optional<Syntax::Language> m_language;
     Vector<size_t> m_breakpoint_lines;
     Optional<size_t> m_execution_position;
diff --git a/Userland/DevTools/HackStudio/Debugger/BacktraceModel.cpp b/Userland/DevTools/HackStudio/Debugger/BacktraceModel.cpp
index c6835f0e7ae..cc2d7439253 100644
--- a/Userland/DevTools/HackStudio/Debugger/BacktraceModel.cpp
+++ b/Userland/DevTools/HackStudio/Debugger/BacktraceModel.cpp
@@ -46,7 +46,7 @@ Vector<BacktraceModel::FrameInfo> BacktraceModel::create_backtrace(Debug::Proces
         // We need to go back to the 'call' instruction to get accurate source position information.
         if (frame_index > 0)
             --current_instruction;
-        DeprecatedString name = lib->debug_info->elf().symbolicate(current_instruction - lib->base_address);
+        ByteString name = lib->debug_info->elf().symbolicate(current_instruction - lib->base_address);
         if (name.is_empty()) {
             dbgln("BacktraceModel: couldn't find containing function for address: {:p} (library={})", current_instruction, lib->name);
             name = "<missing>";
diff --git a/Userland/DevTools/HackStudio/Debugger/BacktraceModel.h b/Userland/DevTools/HackStudio/Debugger/BacktraceModel.h
index 56e9b5e30db..e3770b47a78 100644
--- a/Userland/DevTools/HackStudio/Debugger/BacktraceModel.h
+++ b/Userland/DevTools/HackStudio/Debugger/BacktraceModel.h
@@ -34,7 +34,7 @@ public:
     virtual GUI::ModelIndex index(int row, int column, const GUI::ModelIndex&) const override;
 
     struct FrameInfo {
-        DeprecatedString function_name;
+        ByteString function_name;
         FlatPtr instruction_address { 0 };
         FlatPtr frame_base { 0 };
         Optional<Debug::DebugInfo::SourcePosition> m_source_position;
diff --git a/Userland/DevTools/HackStudio/Debugger/BreakpointCallback.h b/Userland/DevTools/HackStudio/Debugger/BreakpointCallback.h
index 99be9747930..b57fa473e14 100644
--- a/Userland/DevTools/HackStudio/Debugger/BreakpointCallback.h
+++ b/Userland/DevTools/HackStudio/Debugger/BreakpointCallback.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/Types.h>
 
@@ -17,5 +17,5 @@ enum class BreakpointChange {
     Removed,
 };
 
-using BreakpointChangeCallback = Function<void(DeprecatedString const& file, size_t line, BreakpointChange)>;
+using BreakpointChangeCallback = Function<void(ByteString const& file, size_t line, BreakpointChange)>;
 }
diff --git a/Userland/DevTools/HackStudio/Debugger/Debugger.cpp b/Userland/DevTools/HackStudio/Debugger/Debugger.cpp
index 57a91318a86..2a5a193fcec 100644
--- a/Userland/DevTools/HackStudio/Debugger/Debugger.cpp
+++ b/Userland/DevTools/HackStudio/Debugger/Debugger.cpp
@@ -18,7 +18,7 @@ Debugger& Debugger::the()
 }
 
 void Debugger::initialize(
-    DeprecatedString source_root,
+    ByteString source_root,
     Function<HasControlPassedToUser(PtraceRegisters const&)> on_stop_callback,
     Function<void()> on_continue_callback,
     Function<void()> on_exit_callback,
@@ -33,7 +33,7 @@ bool Debugger::is_initialized()
 }
 
 Debugger::Debugger(
-    DeprecatedString source_root,
+    ByteString source_root,
     Function<HasControlPassedToUser(PtraceRegisters const&)> on_stop_callback,
     Function<void()> on_continue_callback,
     Function<void()> on_exit_callback,
@@ -48,7 +48,7 @@ Debugger::Debugger(
     pthread_cond_init(&m_ui_action_cond, nullptr);
 }
 
-void Debugger::on_breakpoint_change(DeprecatedString const& file, size_t line, BreakpointChange change_type)
+void Debugger::on_breakpoint_change(ByteString const& file, size_t line, BreakpointChange change_type)
 {
     auto position = create_source_position(file, line);
 
@@ -80,7 +80,7 @@ void Debugger::on_breakpoint_change(DeprecatedString const& file, size_t line, B
     }
 }
 
-bool Debugger::set_execution_position(DeprecatedString const& file, size_t line)
+bool Debugger::set_execution_position(ByteString const& file, size_t line)
 {
     auto position = create_source_position(file, line);
     auto session = Debugger::the().session();
@@ -95,11 +95,11 @@ bool Debugger::set_execution_position(DeprecatedString const& file, size_t line)
     return true;
 }
 
-Debug::DebugInfo::SourcePosition Debugger::create_source_position(DeprecatedString const& file, size_t line)
+Debug::DebugInfo::SourcePosition Debugger::create_source_position(ByteString const& file, size_t line)
 {
     if (file.starts_with('/'))
         return { file, line + 1 };
-    return { LexicalPath::canonicalized_path(DeprecatedString::formatted("{}/{}", m_source_root, file)), line + 1 };
+    return { LexicalPath::canonicalized_path(ByteString::formatted("{}/{}", m_source_root, file)), line + 1 };
 }
 
 intptr_t Debugger::start_static()
diff --git a/Userland/DevTools/HackStudio/Debugger/Debugger.h b/Userland/DevTools/HackStudio/Debugger/Debugger.h
index 656d2983c40..c6b833b005c 100644
--- a/Userland/DevTools/HackStudio/Debugger/Debugger.h
+++ b/Userland/DevTools/HackStudio/Debugger/Debugger.h
@@ -26,7 +26,7 @@ public:
     };
 
     static void initialize(
-        DeprecatedString source_root,
+        ByteString source_root,
         Function<HasControlPassedToUser(PtraceRegisters const&)> on_stop_callback,
         Function<void()> on_continue_callback,
         Function<void()> on_exit_callback,
@@ -34,11 +34,11 @@ public:
 
     static bool is_initialized();
 
-    void on_breakpoint_change(DeprecatedString const& file, size_t line, BreakpointChange change_type);
-    bool set_execution_position(DeprecatedString const& file, size_t line);
+    void on_breakpoint_change(ByteString const& file, size_t line, BreakpointChange change_type);
+    bool set_execution_position(ByteString const& file, size_t line);
 
-    void set_executable_path(DeprecatedString const& path) { m_executable_path = path; }
-    void set_source_root(DeprecatedString const& source_root) { m_source_root = source_root; }
+    void set_executable_path(ByteString const& path) { m_executable_path = path; }
+    void set_source_root(ByteString const& source_root) { m_source_root = source_root; }
     void set_pid_to_attach(pid_t pid) { m_pid_to_attach = pid; }
 
     Debug::DebugSession* session() { return m_debug_session.ptr(); }
@@ -94,13 +94,13 @@ private:
     };
 
     explicit Debugger(
-        DeprecatedString source_root,
+        ByteString source_root,
         Function<HasControlPassedToUser(PtraceRegisters const&)> on_stop_callback,
         Function<void()> on_continue_callback,
         Function<void()> on_exit_callback,
         Function<void(float)> on_initialization_progress);
 
-    Debug::DebugInfo::SourcePosition create_source_position(DeprecatedString const& file, size_t line);
+    Debug::DebugInfo::SourcePosition create_source_position(ByteString const& file, size_t line);
 
     void start();
     int debugger_loop(Debug::DebugSession::DesiredInitialDebugeeState);
@@ -118,7 +118,7 @@ private:
     CreateDebugSessionResult create_debug_session();
 
     OwnPtr<Debug::DebugSession> m_debug_session;
-    DeprecatedString m_source_root;
+    ByteString m_source_root;
     DebuggingState m_state;
 
     pthread_mutex_t m_ui_action_mutex {};
@@ -127,7 +127,7 @@ private:
 
     Vector<Debug::DebugInfo::SourcePosition> m_breakpoints;
 
-    DeprecatedString m_executable_path;
+    ByteString m_executable_path;
     Optional<pid_t> m_pid_to_attach;
 
     Function<HasControlPassedToUser(PtraceRegisters const&)> m_on_stopped_callback;
diff --git a/Userland/DevTools/HackStudio/Debugger/DisassemblyModel.cpp b/Userland/DevTools/HackStudio/Debugger/DisassemblyModel.cpp
index 956a133c8ea..cadb7141dc7 100644
--- a/Userland/DevTools/HackStudio/Debugger/DisassemblyModel.cpp
+++ b/Userland/DevTools/HackStudio/Debugger/DisassemblyModel.cpp
@@ -60,7 +60,7 @@ DisassemblyModel::DisassemblyModel(Debug::DebugSession const& debug_session, Ptr
         if (!insn.has_value())
             break;
         FlatPtr address_in_profiled_program = symbol.value().value() + offset_into_symbol;
-        auto disassembly = insn.value().to_deprecated_string(address_in_profiled_program, &symbol_provider);
+        auto disassembly = insn.value().to_byte_string(address_in_profiled_program, &symbol_provider);
         StringView instruction_bytes = view.substring_view(offset_into_symbol, insn.value().length());
         m_instructions.append({ insn.value(), disassembly, instruction_bytes, address_in_profiled_program });
 
@@ -93,12 +93,12 @@ GUI::Variant DisassemblyModel::data(const GUI::ModelIndex& index, GUI::ModelRole
 
     if (role == GUI::ModelRole::Display) {
         if (index.column() == Column::Address)
-            return DeprecatedString::formatted("{:p}", insn.address);
+            return ByteString::formatted("{:p}", insn.address);
         if (index.column() == Column::InstructionBytes) {
             StringBuilder builder;
             for (auto ch : insn.bytes)
                 builder.appendff("{:02x} ", static_cast<unsigned char>(ch));
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         }
         if (index.column() == Column::Disassembly)
             return insn.disassembly;
diff --git a/Userland/DevTools/HackStudio/Debugger/DisassemblyModel.h b/Userland/DevTools/HackStudio/Debugger/DisassemblyModel.h
index 33ee35777d4..c6239e02162 100644
--- a/Userland/DevTools/HackStudio/Debugger/DisassemblyModel.h
+++ b/Userland/DevTools/HackStudio/Debugger/DisassemblyModel.h
@@ -22,7 +22,7 @@ namespace HackStudio {
 
 struct InstructionData {
     X86::Instruction insn;
-    DeprecatedString disassembly;
+    ByteString disassembly;
     StringView bytes;
     FlatPtr address { 0 };
 };
diff --git a/Userland/DevTools/HackStudio/Debugger/DisassemblyWidget.cpp b/Userland/DevTools/HackStudio/Debugger/DisassemblyWidget.cpp
index 0139a485997..9382a23d76a 100644
--- a/Userland/DevTools/HackStudio/Debugger/DisassemblyWidget.cpp
+++ b/Userland/DevTools/HackStudio/Debugger/DisassemblyWidget.cpp
@@ -49,7 +49,7 @@ void DisassemblyWidget::update_state(Debug::DebugSession const& debug_session, P
             return;
         auto containing_function = lib->debug_info->get_containing_function(regs.ip() - lib->base_address);
         if (containing_function.has_value())
-            m_function_name_label->set_text(String::from_deprecated_string(containing_function.value().name).release_value_but_fixme_should_propagate_errors());
+            m_function_name_label->set_text(String::from_byte_string(containing_function.value().name).release_value_but_fixme_should_propagate_errors());
         else
             m_function_name_label->set_text("<missing>"_string);
         show_disassembly();
@@ -73,7 +73,7 @@ void DisassemblyWidget::show_disassembly()
     m_unavailable_disassembly_widget->set_visible(false);
 }
 
-void DisassemblyWidget::hide_disassembly(DeprecatedString const& reason)
+void DisassemblyWidget::hide_disassembly(ByteString const& reason)
 {
     m_top_container->set_visible(false);
     m_disassembly_view->set_visible(false);
diff --git a/Userland/DevTools/HackStudio/Debugger/DisassemblyWidget.h b/Userland/DevTools/HackStudio/Debugger/DisassemblyWidget.h
index d695e600c63..61277660164 100644
--- a/Userland/DevTools/HackStudio/Debugger/DisassemblyWidget.h
+++ b/Userland/DevTools/HackStudio/Debugger/DisassemblyWidget.h
@@ -21,18 +21,18 @@ class UnavailableDisassemblyWidget final : public GUI::Frame {
 public:
     virtual ~UnavailableDisassemblyWidget() override { }
 
-    DeprecatedString const& reason() const { return m_reason; }
-    void set_reason(DeprecatedString const& text) { m_reason = text; }
+    ByteString const& reason() const { return m_reason; }
+    void set_reason(ByteString const& text) { m_reason = text; }
 
 private:
-    UnavailableDisassemblyWidget(DeprecatedString const& reason)
+    UnavailableDisassemblyWidget(ByteString const& reason)
         : m_reason(reason)
     {
     }
 
     virtual void paint_event(GUI::PaintEvent& event) override;
 
-    DeprecatedString m_reason;
+    ByteString m_reason;
 };
 
 class DisassemblyWidget final : public GUI::Widget {
@@ -47,7 +47,7 @@ private:
     DisassemblyWidget();
 
     void show_disassembly();
-    void hide_disassembly(DeprecatedString const&);
+    void hide_disassembly(ByteString const&);
 
     RefPtr<GUI::Widget> m_top_container;
     RefPtr<GUI::TableView> m_disassembly_view;
diff --git a/Userland/DevTools/HackStudio/Debugger/RegistersModel.cpp b/Userland/DevTools/HackStudio/Debugger/RegistersModel.cpp
index 1b09445d90b..127f0248710 100644
--- a/Userland/DevTools/HackStudio/Debugger/RegistersModel.cpp
+++ b/Userland/DevTools/HackStudio/Debugger/RegistersModel.cpp
@@ -118,7 +118,7 @@ GUI::Variant RegistersModel::data(const GUI::ModelIndex& index, GUI::ModelRole r
         if (index.column() == Column::Register)
             return reg.name;
         if (index.column() == Column::Value)
-            return DeprecatedString::formatted("{:p}", reg.value);
+            return ByteString::formatted("{:p}", reg.value);
         return {};
     }
     return {};
diff --git a/Userland/DevTools/HackStudio/Debugger/RegistersModel.h b/Userland/DevTools/HackStudio/Debugger/RegistersModel.h
index 0d4505b2ea8..b9d347c81fe 100644
--- a/Userland/DevTools/HackStudio/Debugger/RegistersModel.h
+++ b/Userland/DevTools/HackStudio/Debugger/RegistersModel.h
@@ -14,7 +14,7 @@
 namespace HackStudio {
 
 struct RegisterData {
-    DeprecatedString name;
+    ByteString name;
     FlatPtr value;
     bool changed { false };
 };
diff --git a/Userland/DevTools/HackStudio/Debugger/VariablesModel.cpp b/Userland/DevTools/HackStudio/Debugger/VariablesModel.cpp
index 2ea9d5eb197..8b5d22516a7 100644
--- a/Userland/DevTools/HackStudio/Debugger/VariablesModel.cpp
+++ b/Userland/DevTools/HackStudio/Debugger/VariablesModel.cpp
@@ -55,7 +55,7 @@ int VariablesModel::row_count(const GUI::ModelIndex& index) const
     return node->members.size();
 }
 
-static DeprecatedString variable_value_as_string(Debug::DebugInfo::VariableInfo const& variable)
+static ByteString variable_value_as_string(Debug::DebugInfo::VariableInfo const& variable)
 {
     if (variable.location_type != Debug::DebugInfo::VariableInfo::LocationType::Address)
         return "N/A";
@@ -69,20 +69,20 @@ static DeprecatedString variable_value_as_string(Debug::DebugInfo::VariableInfo
             return enumerator->constant_data.as_u32 == enumerator_value;
         });
         if (it.is_end())
-            return DeprecatedString::formatted("Unknown ({})", value.value());
-        return DeprecatedString::formatted("{}::{}", variable.type_name, (*it)->name);
+            return ByteString::formatted("Unknown ({})", value.value());
+        return ByteString::formatted("{}::{}", variable.type_name, (*it)->name);
     }
 
     if (variable.type_name == "int") {
         auto value = Debugger::the().session()->peek(variable_address);
         VERIFY(value.has_value());
-        return DeprecatedString::formatted("{}", static_cast<int>(value.value()));
+        return ByteString::formatted("{}", static_cast<int>(value.value()));
     }
 
     if (variable.type_name == "char") {
         auto value = Debugger::the().session()->peek(variable_address);
         VERIFY(value.has_value());
-        return DeprecatedString::formatted("'{0:c}'", (char)value.value());
+        return ByteString::formatted("'{0:c}'", (char)value.value());
     }
 
     if (variable.type_name == "bool") {
@@ -91,13 +91,13 @@ static DeprecatedString variable_value_as_string(Debug::DebugInfo::VariableInfo
         return (value.value() & 1) ? "true" : "false";
     }
 
-    return DeprecatedString::formatted("type: {} @ {:p}, ", variable.type_name, variable_address);
+    return ByteString::formatted("type: {} @ {:p}, ", variable.type_name, variable_address);
 }
 
 static Optional<u32> string_to_variable_value(StringView string_value, Debug::DebugInfo::VariableInfo const& variable)
 {
     if (variable.is_enum_type()) {
-        auto prefix_string = DeprecatedString::formatted("{}::", variable.type_name);
+        auto prefix_string = ByteString::formatted("{}::", variable.type_name);
         auto string_to_use = string_value;
         if (string_value.starts_with(prefix_string))
             string_to_use = string_value.substring_view(prefix_string.length(), string_value.length() - prefix_string.length());
@@ -143,7 +143,7 @@ void VariablesModel::set_variable_value(const GUI::ModelIndex& index, StringView
 
     GUI::MessageBox::show(
         parent_window,
-        DeprecatedString::formatted("String value \"{}\" could not be converted to a value of type {}.", string_value, variable->type_name),
+        ByteString::formatted("String value \"{}\" could not be converted to a value of type {}.", string_value, variable->type_name),
         "Set value failed"sv,
         GUI::MessageBox::Type::Error);
 }
@@ -154,7 +154,7 @@ GUI::Variant VariablesModel::data(const GUI::ModelIndex& index, GUI::ModelRole r
     switch (role) {
     case GUI::ModelRole::Display: {
         auto value_as_string = variable_value_as_string(*variable);
-        return DeprecatedString::formatted("{}: {}", variable->name, value_as_string);
+        return ByteString::formatted("{}: {}", variable->name, value_as_string);
     }
     case GUI::ModelRole::Icon:
         return m_variable_icon;
diff --git a/Userland/DevTools/HackStudio/Dialogs/Git/GitCommitDialog.h b/Userland/DevTools/HackStudio/Dialogs/Git/GitCommitDialog.h
index 1d3d0e321fb..20145d16190 100644
--- a/Userland/DevTools/HackStudio/Dialogs/Git/GitCommitDialog.h
+++ b/Userland/DevTools/HackStudio/Dialogs/Git/GitCommitDialog.h
@@ -15,7 +15,7 @@
 
 namespace HackStudio {
 
-using OnCommitCallback = Function<void(DeprecatedString const& message)>;
+using OnCommitCallback = Function<void(ByteString const& message)>;
 
 class GitCommitDialog final : public GUI::Dialog {
     C_OBJECT(GitCommitDialog);
diff --git a/Userland/DevTools/HackStudio/Dialogs/NewProjectDialog.cpp b/Userland/DevTools/HackStudio/Dialogs/NewProjectDialog.cpp
index e55d35e22e3..dbf2643fbd7 100644
--- a/Userland/DevTools/HackStudio/Dialogs/NewProjectDialog.cpp
+++ b/Userland/DevTools/HackStudio/Dialogs/NewProjectDialog.cpp
@@ -10,7 +10,7 @@
 #include <DevTools/HackStudio/Dialogs/NewProjectDialogGML.h>
 #include <DevTools/HackStudio/ProjectTemplate.h>
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <LibCore/Directory.h>
 #include <LibFileSystem/FileSystem.h>
@@ -89,7 +89,7 @@ NewProjectDialog::NewProjectDialog(GUI::Window* parent)
 
     m_browse_button = *find_descendant_of_type_named<GUI::Button>("browse_button");
     m_browse_button->on_click = [this](auto) {
-        Optional<DeprecatedString> path = GUI::FilePicker::get_open_filepath(this, {}, Core::StandardPaths::home_directory(), true);
+        Optional<ByteString> path = GUI::FilePicker::get_open_filepath(this, {}, Core::StandardPaths::home_directory(), true);
         if (path.has_value())
             m_create_in_input->set_text(path.value().view());
     };
@@ -113,7 +113,7 @@ void NewProjectDialog::update_dialog()
     m_input_valid = true;
 
     if (project_template) {
-        m_description_label->set_text(String::from_deprecated_string(project_template->description()).release_value_but_fixme_should_propagate_errors());
+        m_description_label->set_text(String::from_byte_string(project_template->description()).release_value_but_fixme_should_propagate_errors());
     } else {
         m_description_label->set_text("Select a project template to continue."_string);
         m_input_valid = false;
@@ -122,7 +122,7 @@ void NewProjectDialog::update_dialog()
     auto maybe_project_path = get_project_full_path();
 
     if (maybe_project_path.has_value()) {
-        m_full_path_label->set_text(String::from_deprecated_string(maybe_project_path.value()).release_value_but_fixme_should_propagate_errors());
+        m_full_path_label->set_text(String::from_byte_string(maybe_project_path.value()).release_value_but_fixme_should_propagate_errors());
     } else {
         m_full_path_label->set_text("Invalid name or creation directory."_string);
         m_input_valid = false;
@@ -131,7 +131,7 @@ void NewProjectDialog::update_dialog()
     m_ok_button->set_enabled(m_input_valid);
 }
 
-Optional<DeprecatedString> NewProjectDialog::get_available_project_name()
+Optional<ByteString> NewProjectDialog::get_available_project_name()
 {
     auto create_in = m_create_in_input->text();
     auto chosen_name = m_name_input->text();
@@ -148,16 +148,16 @@ Optional<DeprecatedString> NewProjectDialog::get_available_project_name()
     for (int i = 0; i < 1000; i++) {
         auto candidate = (i == 0)
             ? chosen_name
-            : DeprecatedString::formatted("{}-{}", chosen_name, i);
+            : ByteString::formatted("{}-{}", chosen_name, i);
 
-        if (!FileSystem::exists(DeprecatedString::formatted("{}/{}", create_in, candidate)))
+        if (!FileSystem::exists(ByteString::formatted("{}/{}", create_in, candidate)))
             return candidate;
     }
 
     return {};
 }
 
-Optional<DeprecatedString> NewProjectDialog::get_project_full_path()
+Optional<ByteString> NewProjectDialog::get_project_full_path()
 {
     // Do not permit forward-slashes in project names
     if (m_name_input->text().contains('/'))
@@ -189,13 +189,13 @@ void NewProjectDialog::do_create_project()
 
     auto create_in = m_create_in_input->text();
     if (!FileSystem::exists(create_in) || !FileSystem::is_directory(create_in)) {
-        auto result = GUI::MessageBox::show(this, DeprecatedString::formatted("The directory \"{}\" does not exist yet, would you like to create it?", create_in), "New Project"sv, GUI::MessageBox::Type::Question, GUI::MessageBox::InputType::YesNo);
+        auto result = GUI::MessageBox::show(this, ByteString::formatted("The directory \"{}\" does not exist yet, would you like to create it?", create_in), "New Project"sv, GUI::MessageBox::Type::Question, GUI::MessageBox::InputType::YesNo);
         if (result != GUI::MessageBox::ExecResult::Yes)
             return;
 
         auto created = Core::Directory::create(maybe_project_full_path.value(), Core::Directory::CreateDirectories::Yes);
         if (created.is_error()) {
-            GUI::MessageBox::show_error(this, DeprecatedString::formatted("Could not create directory \"{}\"", create_in));
+            GUI::MessageBox::show_error(this, ByteString::formatted("Could not create directory \"{}\"", create_in));
             return;
         }
     }
@@ -206,7 +206,7 @@ void NewProjectDialog::do_create_project()
         m_created_project_path = maybe_project_full_path.value();
         done(ExecResult::OK);
     } else {
-        GUI::MessageBox::show_error(this, DeprecatedString::formatted("Could not create project: {}", creation_result.error()));
+        GUI::MessageBox::show_error(this, ByteString::formatted("Could not create project: {}", creation_result.error()));
     }
 }
 
diff --git a/Userland/DevTools/HackStudio/Dialogs/NewProjectDialog.h b/Userland/DevTools/HackStudio/Dialogs/NewProjectDialog.h
index ec74124210e..14219682e3e 100644
--- a/Userland/DevTools/HackStudio/Dialogs/NewProjectDialog.h
+++ b/Userland/DevTools/HackStudio/Dialogs/NewProjectDialog.h
@@ -24,15 +24,15 @@ class NewProjectDialog : public GUI::Dialog {
 public:
     static ExecResult show(GUI::Window* parent_window);
 
-    Optional<DeprecatedString> created_project_path() const { return m_created_project_path; }
+    Optional<ByteString> created_project_path() const { return m_created_project_path; }
 
 private:
     NewProjectDialog(GUI::Window* parent);
     virtual ~NewProjectDialog() override = default;
 
     void update_dialog();
-    Optional<DeprecatedString> get_available_project_name();
-    Optional<DeprecatedString> get_project_full_path();
+    Optional<ByteString> get_available_project_name();
+    Optional<ByteString> get_project_full_path();
 
     void do_create_project();
 
@@ -53,7 +53,7 @@ private:
     RefPtr<GUI::Button> m_cancel_button;
     RefPtr<GUI::Button> m_browse_button;
 
-    Optional<DeprecatedString> m_created_project_path;
+    Optional<ByteString> m_created_project_path;
 };
 
 }
diff --git a/Userland/DevTools/HackStudio/Editor.cpp b/Userland/DevTools/HackStudio/Editor.cpp
index 6c782c27026..3de246e535b 100644
--- a/Userland/DevTools/HackStudio/Editor.cpp
+++ b/Userland/DevTools/HackStudio/Editor.cpp
@@ -163,9 +163,9 @@ void Editor::paint_event(GUI::PaintEvent& event)
     }
 }
 
-static HashMap<DeprecatedString, DeprecatedString>& man_paths()
+static HashMap<ByteString, ByteString>& man_paths()
 {
-    static HashMap<DeprecatedString, DeprecatedString> paths;
+    static HashMap<ByteString, ByteString> paths;
     if (paths.is_empty()) {
         auto json = Config::read_string("HackStudio"sv, "Global"sv, "DocumentationSearchPaths"sv);
         AK::JsonParser parser(json);
@@ -194,7 +194,7 @@ static HashMap<DeprecatedString, DeprecatedString>& man_paths()
     return paths;
 }
 
-void Editor::show_documentation_tooltip_if_available(DeprecatedString const& hovered_token, Gfx::IntPoint screen_location)
+void Editor::show_documentation_tooltip_if_available(ByteString const& hovered_token, Gfx::IntPoint screen_location)
 {
     auto it = man_paths().find(hovered_token);
     if (it == man_paths().end()) {
@@ -384,11 +384,11 @@ void Editor::leave_event(Core::Event& event)
     GUI::TextEditor::leave_event(event);
 }
 
-static HashMap<DeprecatedString, DeprecatedString>& include_paths()
+static HashMap<ByteString, ByteString>& include_paths()
 {
-    static HashMap<DeprecatedString, DeprecatedString> paths;
+    static HashMap<ByteString, ByteString> paths;
 
-    auto add_directory = [](DeprecatedString base, Optional<DeprecatedString> recursive, auto handle_directory) -> void {
+    auto add_directory = [](ByteString base, Optional<ByteString> recursive, auto handle_directory) -> void {
         Core::DirIterator it(recursive.value_or(base), Core::DirIterator::Flags::SkipDots);
         while (it.has_next()) {
             auto path = it.next_full_path();
@@ -412,7 +412,7 @@ static HashMap<DeprecatedString, DeprecatedString>& include_paths()
     return paths;
 }
 
-void Editor::navigate_to_include_if_available(DeprecatedString path)
+void Editor::navigate_to_include_if_available(ByteString path)
 {
     auto it = include_paths().find(path);
     if (it == include_paths().end()) {
@@ -587,7 +587,7 @@ void Editor::on_identifier_click(const GUI::TextDocumentSpan& span)
     if (!m_language_client)
         return;
 
-    m_language_client->on_declaration_found = [](DeprecatedString const& file, size_t line, size_t column) {
+    m_language_client->on_declaration_found = [](ByteString const& file, size_t line, size_t column) {
         HackStudio::open_file(file, line, column);
     };
     m_language_client->search_declaration(code_document().file_path(), span.range.start().line(), span.range.start().column());
@@ -704,7 +704,7 @@ void Editor::handle_function_parameters_hint_request()
     if (!m_language_client)
         return;
 
-    m_language_client->on_function_parameters_hint_result = [this](Vector<DeprecatedString> const& params, size_t argument_index) {
+    m_language_client->on_function_parameters_hint_result = [this](Vector<ByteString> const& params, size_t argument_index) {
         dbgln("on_function_parameters_hint_result");
 
         StringBuilder html;
@@ -722,7 +722,7 @@ void Editor::handle_function_parameters_hint_request()
         }
         html.append("<style>body { background-color: #dac7b5; }</style>"sv);
 
-        s_tooltip_page_view->load_html(html.to_deprecated_string());
+        s_tooltip_page_view->load_html(html.to_byte_string());
 
         auto cursor_rect = current_editor().cursor_content_rect().location().translated(screen_relative_rect().location());
 
diff --git a/Userland/DevTools/HackStudio/Editor.h b/Userland/DevTools/HackStudio/Editor.h
index 2d6aa5dafa5..e1461dac6d7 100644
--- a/Userland/DevTools/HackStudio/Editor.h
+++ b/Userland/DevTools/HackStudio/Editor.h
@@ -28,7 +28,7 @@ public:
 
     virtual ~Editor() override = default;
 
-    Function<void(DeprecatedString)> on_open;
+    Function<void(ByteString)> on_open;
 
     EditorWrapper& wrapper();
     EditorWrapper const& wrapper() const;
@@ -72,8 +72,8 @@ private:
     virtual void leave_event(Core::Event&) override;
     virtual void keydown_event(GUI::KeyEvent&) override;
 
-    void show_documentation_tooltip_if_available(DeprecatedString const&, Gfx::IntPoint screen_location);
-    void navigate_to_include_if_available(DeprecatedString);
+    void show_documentation_tooltip_if_available(ByteString const&, Gfx::IntPoint screen_location);
+    void navigate_to_include_if_available(ByteString);
     void on_navigatable_link_click(const GUI::TextDocumentSpan&);
     void on_identifier_click(const GUI::TextDocumentSpan&);
 
@@ -111,7 +111,7 @@ private:
 
     explicit Editor();
 
-    DeprecatedString m_last_parsed_token;
+    ByteString m_last_parsed_token;
     GUI::TextPosition m_previous_text_position { 0, 0 };
     bool m_hovering_editor { false };
     bool m_hovering_clickable { false };
diff --git a/Userland/DevTools/HackStudio/EditorWrapper.cpp b/Userland/DevTools/HackStudio/EditorWrapper.cpp
index 82edf5e7d86..9077b415371 100644
--- a/Userland/DevTools/HackStudio/EditorWrapper.cpp
+++ b/Userland/DevTools/HackStudio/EditorWrapper.cpp
@@ -34,7 +34,7 @@ EditorWrapper::EditorWrapper()
         set_current_editor_wrapper(this);
     };
 
-    m_editor->on_open = [](DeprecatedString const& path) {
+    m_editor->on_open = [](ByteString const& path) {
         open_file(path);
     };
 
@@ -64,7 +64,7 @@ void EditorWrapper::set_mode_non_displayable()
     editor().document().set_text("The contents of this file could not be displayed. Is it a binary file?"sv);
 }
 
-void EditorWrapper::set_filename(DeprecatedString const& filename)
+void EditorWrapper::set_filename(ByteString const& filename)
 {
     m_filename = filename;
     update_title();
@@ -75,7 +75,7 @@ bool EditorWrapper::save()
 {
     if (filename().is_empty()) {
         auto file_picker_action = GUI::CommonActions::make_save_as_action([&](auto&) {
-            Optional<DeprecatedString> save_path = GUI::FilePicker::get_save_filepath(window(), "file"sv, "txt"sv, project_root().value());
+            Optional<ByteString> save_path = GUI::FilePicker::get_save_filepath(window(), "file"sv, "txt"sv, project_root().value());
             if (save_path.has_value())
                 set_filename(save_path.value());
         });
@@ -99,7 +99,7 @@ void EditorWrapper::update_diff()
     }
 }
 
-void EditorWrapper::set_project_root(DeprecatedString const& project_root)
+void EditorWrapper::set_project_root(ByteString const& project_root)
 {
     m_project_root = project_root;
     auto result = GitRepo::try_to_create(*m_project_root);
@@ -126,7 +126,7 @@ void EditorWrapper::update_title()
 
     if (editor().document().is_modified())
         title.append(" (*)"sv);
-    m_filename_title = title.to_deprecated_string();
+    m_filename_title = title.to_byte_string();
 }
 
 void EditorWrapper::set_debug_mode(bool enabled)
diff --git a/Userland/DevTools/HackStudio/EditorWrapper.h b/Userland/DevTools/HackStudio/EditorWrapper.h
index 30f97a4c8f6..fcbe23d523c 100644
--- a/Userland/DevTools/HackStudio/EditorWrapper.h
+++ b/Userland/DevTools/HackStudio/EditorWrapper.h
@@ -37,12 +37,12 @@ public:
     void set_mode_displayable();
     void set_mode_non_displayable();
     void set_debug_mode(bool);
-    void set_filename(DeprecatedString const&);
-    DeprecatedString const& filename() const { return m_filename; }
-    DeprecatedString const& filename_title() const { return m_filename_title; }
+    void set_filename(ByteString const&);
+    ByteString const& filename() const { return m_filename; }
+    ByteString const& filename_title() const { return m_filename_title; }
 
-    Optional<DeprecatedString> const& project_root() const { return m_project_root; }
-    void set_project_root(DeprecatedString const& project_root);
+    Optional<ByteString> const& project_root() const { return m_project_root; }
+    void set_project_root(ByteString const& project_root);
 
     GitRepo const* git_repo() const { return m_git_repo; }
 
@@ -59,11 +59,11 @@ private:
 
     void update_title();
 
-    DeprecatedString m_filename;
-    DeprecatedString m_filename_title;
+    ByteString m_filename;
+    ByteString m_filename_title;
     RefPtr<Editor> m_editor;
 
-    Optional<DeprecatedString> m_project_root;
+    Optional<ByteString> m_project_root;
     RefPtr<GitRepo> m_git_repo;
     Vector<Diff::Hunk> m_hunks;
 };
diff --git a/Userland/DevTools/HackStudio/FindInFilesWidget.cpp b/Userland/DevTools/HackStudio/FindInFilesWidget.cpp
index f8977c9b5b7..c123e6ea040 100644
--- a/Userland/DevTools/HackStudio/FindInFilesWidget.cpp
+++ b/Userland/DevTools/HackStudio/FindInFilesWidget.cpp
@@ -17,9 +17,9 @@
 namespace HackStudio {
 
 struct Match {
-    DeprecatedString filename;
+    ByteString filename;
     GUI::TextRange range;
-    DeprecatedString text;
+    ByteString text;
 };
 
 class SearchResultsModel final : public GUI::Model {
@@ -105,7 +105,7 @@ static RefPtr<SearchResultsModel> find_in_files(StringView text)
             builder.append(file.document().text_in_range(range));
             builder.append(0x02);
             builder.append(right_part);
-            matches.append({ file.name(), range, builder.to_deprecated_string() });
+            matches.append({ file.name(), range, builder.to_byte_string() });
         }
     });
 
diff --git a/Userland/DevTools/HackStudio/GMLPreviewWidget.cpp b/Userland/DevTools/HackStudio/GMLPreviewWidget.cpp
index 5198a05e2e3..94e3e180545 100644
--- a/Userland/DevTools/HackStudio/GMLPreviewWidget.cpp
+++ b/Userland/DevTools/HackStudio/GMLPreviewWidget.cpp
@@ -10,13 +10,13 @@
 
 namespace HackStudio {
 
-GMLPreviewWidget::GMLPreviewWidget(DeprecatedString const& gml_content)
+GMLPreviewWidget::GMLPreviewWidget(ByteString const& gml_content)
 {
     set_layout<GUI::VerticalBoxLayout>();
     load_gml(gml_content);
 }
 
-void GMLPreviewWidget::load_gml(DeprecatedString const& gml)
+void GMLPreviewWidget::load_gml(ByteString const& gml)
 {
     remove_all_children();
 
diff --git a/Userland/DevTools/HackStudio/GMLPreviewWidget.h b/Userland/DevTools/HackStudio/GMLPreviewWidget.h
index 77419c502e0..17646b0fbc0 100644
--- a/Userland/DevTools/HackStudio/GMLPreviewWidget.h
+++ b/Userland/DevTools/HackStudio/GMLPreviewWidget.h
@@ -14,10 +14,10 @@ namespace HackStudio {
 class GMLPreviewWidget final : public GUI::Widget {
     C_OBJECT(GMLPreviewWidget)
 public:
-    void load_gml(DeprecatedString const&);
+    void load_gml(ByteString const&);
 
 private:
-    explicit GMLPreviewWidget(DeprecatedString const&);
+    explicit GMLPreviewWidget(ByteString const&);
 };
 
 }
diff --git a/Userland/DevTools/HackStudio/Git/DiffViewer.cpp b/Userland/DevTools/HackStudio/Git/DiffViewer.cpp
index 5fd11ef3fe8..7e5e0e53b18 100644
--- a/Userland/DevTools/HackStudio/Git/DiffViewer.cpp
+++ b/Userland/DevTools/HackStudio/Git/DiffViewer.cpp
@@ -135,7 +135,7 @@ Gfx::IntRect DiffViewer::separator_rect() const
         frame_inner_rect().height() };
 }
 
-void DiffViewer::set_content(DeprecatedString const& original, DeprecatedString const& diff)
+void DiffViewer::set_content(ByteString const& original, ByteString const& diff)
 {
     m_original_lines = split_to_lines(original);
     m_hunks = Diff::parse_hunks(diff).release_value_but_fixme_should_propagate_errors();
@@ -151,7 +151,7 @@ DiffViewer::DiffViewer()
     setup_properties();
 }
 
-DiffViewer::DiffViewer(DeprecatedString const& original, DeprecatedString const& diff)
+DiffViewer::DiffViewer(ByteString const& original, ByteString const& diff)
     : m_original_lines(split_to_lines(original))
     , m_hunks(Diff::parse_hunks(diff).release_value_but_fixme_should_propagate_errors())
 {
@@ -165,10 +165,10 @@ void DiffViewer::setup_properties()
     set_foreground_role(ColorRole::BaseText);
 }
 
-Vector<DeprecatedString> DiffViewer::split_to_lines(DeprecatedString const& text)
+Vector<ByteString> DiffViewer::split_to_lines(ByteString const& text)
 {
     // NOTE: This is slightly different than text.split('\n')
-    Vector<DeprecatedString> lines;
+    Vector<ByteString> lines;
     size_t next_line_start_index = 0;
     for (size_t i = 0; i < text.length(); ++i) {
         if (text[i] == '\n') {
diff --git a/Userland/DevTools/HackStudio/Git/DiffViewer.h b/Userland/DevTools/HackStudio/Git/DiffViewer.h
index 24a9283373b..827c7397ea7 100644
--- a/Userland/DevTools/HackStudio/Git/DiffViewer.h
+++ b/Userland/DevTools/HackStudio/Git/DiffViewer.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <LibDiff/Hunks.h>
 #include <LibGUI/AbstractScrollableWidget.h>
@@ -18,10 +18,10 @@ class DiffViewer final : public GUI::AbstractScrollableWidget {
 public:
     virtual ~DiffViewer() override = default;
 
-    void set_content(DeprecatedString const& original, DeprecatedString const& diff);
+    void set_content(ByteString const& original, ByteString const& diff);
 
 private:
-    DiffViewer(DeprecatedString const& original, DeprecatedString const& diff);
+    DiffViewer(ByteString const& original, ByteString const& diff);
     DiffViewer();
 
     void setup_properties();
@@ -45,7 +45,7 @@ private:
 
     void draw_line(GUI::Painter&, StringView line, size_t y_offset, LinePosition, LineType);
 
-    static Vector<DeprecatedString> split_to_lines(DeprecatedString const& text);
+    static Vector<ByteString> split_to_lines(ByteString const& text);
 
     static Gfx::Color red_background();
     static Gfx::Color green_background();
@@ -55,7 +55,7 @@ private:
 
     Gfx::IntRect separator_rect() const;
 
-    Vector<DeprecatedString> m_original_lines;
+    Vector<ByteString> m_original_lines;
     Vector<Diff::Hunk> m_hunks;
 };
 }
diff --git a/Userland/DevTools/HackStudio/Git/GitFilesModel.cpp b/Userland/DevTools/HackStudio/Git/GitFilesModel.cpp
index 4897c7f1027..7311d874b16 100644
--- a/Userland/DevTools/HackStudio/Git/GitFilesModel.cpp
+++ b/Userland/DevTools/HackStudio/Git/GitFilesModel.cpp
@@ -8,12 +8,12 @@
 
 namespace HackStudio {
 
-NonnullRefPtr<GitFilesModel> GitFilesModel::create(Vector<DeprecatedString>&& files)
+NonnullRefPtr<GitFilesModel> GitFilesModel::create(Vector<ByteString>&& files)
 {
     return adopt_ref(*new GitFilesModel(move(files)));
 }
 
-GitFilesModel::GitFilesModel(Vector<DeprecatedString>&& files)
+GitFilesModel::GitFilesModel(Vector<ByteString>&& files)
     : m_files(move(files))
 {
 }
diff --git a/Userland/DevTools/HackStudio/Git/GitFilesModel.h b/Userland/DevTools/HackStudio/Git/GitFilesModel.h
index 98921f40d9d..3a91bcb1b54 100644
--- a/Userland/DevTools/HackStudio/Git/GitFilesModel.h
+++ b/Userland/DevTools/HackStudio/Git/GitFilesModel.h
@@ -14,7 +14,7 @@ namespace HackStudio {
 
 class GitFilesModel final : public GUI::Model {
 public:
-    static NonnullRefPtr<GitFilesModel> create(Vector<DeprecatedString>&& files);
+    static NonnullRefPtr<GitFilesModel> create(Vector<ByteString>&& files);
 
     virtual int row_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override { return m_files.size(); }
     virtual int column_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override { return 1; }
@@ -26,7 +26,7 @@ public:
     virtual GUI::ModelIndex index(int row, int column, const GUI::ModelIndex&) const override;
 
 private:
-    explicit GitFilesModel(Vector<DeprecatedString>&& files);
-    Vector<DeprecatedString> m_files;
+    explicit GitFilesModel(Vector<ByteString>&& files);
+    Vector<ByteString> m_files;
 };
 }
diff --git a/Userland/DevTools/HackStudio/Git/GitFilesView.cpp b/Userland/DevTools/HackStudio/Git/GitFilesView.cpp
index d09fd5d4739..bff70cee402 100644
--- a/Userland/DevTools/HackStudio/Git/GitFilesView.cpp
+++ b/Userland/DevTools/HackStudio/Git/GitFilesView.cpp
@@ -54,7 +54,7 @@ void GitFilesView::mousedown_event(GUI::MouseEvent& event)
     auto data = model()->index(item_index, model_column()).data();
 
     VERIFY(data.is_string());
-    m_action_callback(data.to_deprecated_string());
+    m_action_callback(data.to_byte_string());
 }
 
 };
diff --git a/Userland/DevTools/HackStudio/Git/GitFilesView.h b/Userland/DevTools/HackStudio/Git/GitFilesView.h
index bdc82be6060..c60e076ef64 100644
--- a/Userland/DevTools/HackStudio/Git/GitFilesView.h
+++ b/Userland/DevTools/HackStudio/Git/GitFilesView.h
@@ -13,7 +13,7 @@
 namespace HackStudio {
 
 // A "GitFileAction" is either the staging or the unstaging of a file.
-using GitFileActionCallback = Function<void(DeprecatedString const& file)>;
+using GitFileActionCallback = Function<void(ByteString const& file)>;
 
 class GitFilesView : public GUI::ListView {
     C_OBJECT(GitFilesView)
diff --git a/Userland/DevTools/HackStudio/Git/GitRepo.cpp b/Userland/DevTools/HackStudio/Git/GitRepo.cpp
index 7b3b0e9ba1e..34ec2e2904e 100644
--- a/Userland/DevTools/HackStudio/Git/GitRepo.cpp
+++ b/Userland/DevTools/HackStudio/Git/GitRepo.cpp
@@ -9,7 +9,7 @@
 
 namespace HackStudio {
 
-GitRepo::CreateResult GitRepo::try_to_create(DeprecatedString const& repository_root)
+GitRepo::CreateResult GitRepo::try_to_create(ByteString const& repository_root)
 {
     if (!git_is_installed()) {
         return { CreateResult::Type::GitProgramNotFound, nullptr };
@@ -21,7 +21,7 @@ GitRepo::CreateResult GitRepo::try_to_create(DeprecatedString const& repository_
     return { CreateResult::Type::Success, adopt_ref(*new GitRepo(repository_root)) };
 }
 
-RefPtr<GitRepo> GitRepo::initialize_repository(DeprecatedString const& repository_root)
+RefPtr<GitRepo> GitRepo::initialize_repository(ByteString const& repository_root)
 {
     auto res = command_wrapper({ "init" }, repository_root);
     if (!res.has_value())
@@ -31,7 +31,7 @@ RefPtr<GitRepo> GitRepo::initialize_repository(DeprecatedString const& repositor
     return adopt_ref(*new GitRepo(repository_root));
 }
 
-Vector<DeprecatedString> GitRepo::unstaged_files() const
+Vector<ByteString> GitRepo::unstaged_files() const
 {
     auto modified = modified_files();
     auto untracked = untracked_files();
@@ -39,7 +39,7 @@ Vector<DeprecatedString> GitRepo::unstaged_files() const
     return modified;
 }
 //
-Vector<DeprecatedString> GitRepo::staged_files() const
+Vector<ByteString> GitRepo::staged_files() const
 {
     auto raw_result = command({ "diff", "--cached", "--name-only" });
     if (!raw_result.has_value())
@@ -47,7 +47,7 @@ Vector<DeprecatedString> GitRepo::staged_files() const
     return parse_files_list(*raw_result);
 }
 
-Vector<DeprecatedString> GitRepo::modified_files() const
+Vector<ByteString> GitRepo::modified_files() const
 {
     auto raw_result = command({ "ls-files", "--modified", "--exclude-standard" });
     if (!raw_result.has_value())
@@ -55,7 +55,7 @@ Vector<DeprecatedString> GitRepo::modified_files() const
     return parse_files_list(*raw_result);
 }
 
-Vector<DeprecatedString> GitRepo::untracked_files() const
+Vector<ByteString> GitRepo::untracked_files() const
 {
     auto raw_result = command({ "ls-files", "--others", "--exclude-standard" });
     if (!raw_result.has_value())
@@ -63,27 +63,27 @@ Vector<DeprecatedString> GitRepo::untracked_files() const
     return parse_files_list(*raw_result);
 }
 
-Vector<DeprecatedString> GitRepo::parse_files_list(DeprecatedString const& raw_result)
+Vector<ByteString> GitRepo::parse_files_list(ByteString const& raw_result)
 {
     auto lines = raw_result.split('\n');
-    Vector<DeprecatedString> files;
+    Vector<ByteString> files;
     for (auto const& line : lines) {
         files.empend(line);
     }
     return files;
 }
 
-Optional<DeprecatedString> GitRepo::command(Vector<DeprecatedString> const& command_parts) const
+Optional<ByteString> GitRepo::command(Vector<ByteString> const& command_parts) const
 {
     return command_wrapper(command_parts, m_repository_root);
 }
 
-Optional<DeprecatedString> GitRepo::command_wrapper(Vector<DeprecatedString> const& command_parts, DeprecatedString const& chdir)
+Optional<ByteString> GitRepo::command_wrapper(Vector<ByteString> const& command_parts, ByteString const& chdir)
 {
     auto const result = Core::command("git", command_parts, LexicalPath(chdir));
     if (result.is_error() || result.value().exit_code != 0)
         return {};
-    return DeprecatedString(result.value().output.bytes());
+    return ByteString(result.value().output.bytes());
 }
 
 bool GitRepo::git_is_installed()
@@ -91,37 +91,37 @@ bool GitRepo::git_is_installed()
     return command_wrapper({ "--help" }, "/").has_value();
 }
 
-bool GitRepo::git_repo_exists(DeprecatedString const& repo_root)
+bool GitRepo::git_repo_exists(ByteString const& repo_root)
 {
     return command_wrapper({ "status" }, repo_root).has_value();
 }
 
-bool GitRepo::stage(DeprecatedString const& file)
+bool GitRepo::stage(ByteString const& file)
 {
     return command({ "add", file }).has_value();
 }
 
-bool GitRepo::unstage(DeprecatedString const& file)
+bool GitRepo::unstage(ByteString const& file)
 {
     return command({ "reset", "HEAD", "--", file }).has_value();
 }
 
-bool GitRepo::commit(DeprecatedString const& message)
+bool GitRepo::commit(ByteString const& message)
 {
     return command({ "commit", "-m", message }).has_value();
 }
 
-Optional<DeprecatedString> GitRepo::original_file_content(DeprecatedString const& file) const
+Optional<ByteString> GitRepo::original_file_content(ByteString const& file) const
 {
-    return command({ "show", DeprecatedString::formatted("HEAD:{}", file) });
+    return command({ "show", ByteString::formatted("HEAD:{}", file) });
 }
 
-Optional<DeprecatedString> GitRepo::unstaged_diff(DeprecatedString const& file) const
+Optional<ByteString> GitRepo::unstaged_diff(ByteString const& file) const
 {
     return command({ "diff", "-U0", file.characters() });
 }
 
-bool GitRepo::is_tracked(DeprecatedString const& file) const
+bool GitRepo::is_tracked(ByteString const& file) const
 {
     auto res = command({ "ls-files", file });
     if (!res.has_value())
diff --git a/Userland/DevTools/HackStudio/Git/GitRepo.h b/Userland/DevTools/HackStudio/Git/GitRepo.h
index e4598359ca1..ec04f96ad19 100644
--- a/Userland/DevTools/HackStudio/Git/GitRepo.h
+++ b/Userland/DevTools/HackStudio/Git/GitRepo.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/Optional.h>
 #include <AK/RefCounted.h>
@@ -28,37 +28,37 @@ public:
         RefPtr<GitRepo> repo;
     };
 
-    static CreateResult try_to_create(DeprecatedString const& repository_root);
-    static RefPtr<GitRepo> initialize_repository(DeprecatedString const& repository_root);
+    static CreateResult try_to_create(ByteString const& repository_root);
+    static RefPtr<GitRepo> initialize_repository(ByteString const& repository_root);
 
-    bool stage(DeprecatedString const& file);
-    bool unstage(DeprecatedString const& file);
-    bool commit(DeprecatedString const& message);
-    bool is_tracked(DeprecatedString const& file) const;
+    bool stage(ByteString const& file);
+    bool unstage(ByteString const& file);
+    bool commit(ByteString const& message);
+    bool is_tracked(ByteString const& file) const;
 
-    Vector<DeprecatedString> unstaged_files() const;
-    Vector<DeprecatedString> staged_files() const;
-    Optional<DeprecatedString> original_file_content(DeprecatedString const& file) const;
-    Optional<DeprecatedString> unstaged_diff(DeprecatedString const& file) const;
+    Vector<ByteString> unstaged_files() const;
+    Vector<ByteString> staged_files() const;
+    Optional<ByteString> original_file_content(ByteString const& file) const;
+    Optional<ByteString> unstaged_diff(ByteString const& file) const;
 
 private:
     static bool git_is_installed();
-    static bool git_repo_exists(DeprecatedString const& repo_root);
+    static bool git_repo_exists(ByteString const& repo_root);
 
-    static Optional<DeprecatedString> command_wrapper(Vector<DeprecatedString> const& command_parts, DeprecatedString const& chdir);
-    static Vector<DeprecatedString> parse_files_list(DeprecatedString const&);
+    static Optional<ByteString> command_wrapper(Vector<ByteString> const& command_parts, ByteString const& chdir);
+    static Vector<ByteString> parse_files_list(ByteString const&);
 
-    explicit GitRepo(DeprecatedString const& repository_root)
+    explicit GitRepo(ByteString const& repository_root)
         : m_repository_root(repository_root)
     {
     }
 
-    Vector<DeprecatedString> modified_files() const;
-    Vector<DeprecatedString> untracked_files() const;
+    Vector<ByteString> modified_files() const;
+    Vector<ByteString> untracked_files() const;
 
-    Optional<DeprecatedString> command(Vector<DeprecatedString> const& command_parts) const;
+    Optional<ByteString> command(Vector<ByteString> const& command_parts) const;
 
-    DeprecatedString m_repository_root;
+    ByteString m_repository_root;
 };
 
 }
diff --git a/Userland/DevTools/HackStudio/Git/GitWidget.cpp b/Userland/DevTools/HackStudio/Git/GitWidget.cpp
index 6d95dd4b39b..02d853f7c50 100644
--- a/Userland/DevTools/HackStudio/Git/GitWidget.cpp
+++ b/Userland/DevTools/HackStudio/Git/GitWidget.cpp
@@ -118,7 +118,7 @@ void GitWidget::refresh()
     m_staged_files->set_model(GitFilesModel::create(m_git_repo->staged_files()));
 }
 
-void GitWidget::stage_file(DeprecatedString const& file)
+void GitWidget::stage_file(ByteString const& file)
 {
     dbgln("staging: {}", file);
     bool rc = m_git_repo->stage(file);
@@ -126,7 +126,7 @@ void GitWidget::stage_file(DeprecatedString const& file)
     refresh();
 }
 
-void GitWidget::unstage_file(DeprecatedString const& file)
+void GitWidget::unstage_file(ByteString const& file)
 {
     dbgln("unstaging: {}", file);
     bool rc = m_git_repo->unstage(file);
@@ -154,7 +154,7 @@ void GitWidget::set_view_diff_callback(ViewDiffCallback callback)
     m_view_diff_callback = move(callback);
 }
 
-void GitWidget::show_diff(DeprecatedString const& file_path)
+void GitWidget::show_diff(ByteString const& file_path)
 {
     if (!m_git_repo->is_tracked(file_path)) {
         auto file = Core::File::open(file_path, Core::File::OpenMode::Read).release_value_but_fixme_should_propagate_errors();
@@ -168,7 +168,7 @@ void GitWidget::show_diff(DeprecatedString const& file_path)
     m_view_diff_callback(original_content.value(), diff.value());
 }
 
-void GitWidget::change_repo(DeprecatedString const& repo_root)
+void GitWidget::change_repo(ByteString const& repo_root)
 {
     m_repo_root = repo_root;
     m_git_repo = nullptr;
diff --git a/Userland/DevTools/HackStudio/Git/GitWidget.h b/Userland/DevTools/HackStudio/Git/GitWidget.h
index 5240662bef1..18c1e4860a9 100644
--- a/Userland/DevTools/HackStudio/Git/GitWidget.h
+++ b/Userland/DevTools/HackStudio/Git/GitWidget.h
@@ -14,7 +14,7 @@
 
 namespace HackStudio {
 
-using ViewDiffCallback = Function<void(DeprecatedString const& original_content, DeprecatedString const& diff)>;
+using ViewDiffCallback = Function<void(ByteString const& original_content, ByteString const& diff)>;
 
 class GitWidget final : public GUI::Widget {
     C_OBJECT(GitWidget)
@@ -24,19 +24,19 @@ public:
     void refresh();
     void set_view_diff_callback(ViewDiffCallback callback);
     bool initialized() const { return !m_git_repo.is_null(); }
-    void change_repo(DeprecatedString const& repo_root);
+    void change_repo(ByteString const& repo_root);
 
 private:
     explicit GitWidget();
 
     bool initialize();
     bool initialize_if_needed();
-    void stage_file(DeprecatedString const&);
-    void unstage_file(DeprecatedString const&);
+    void stage_file(ByteString const&);
+    void unstage_file(ByteString const&);
     void commit();
-    void show_diff(DeprecatedString const&);
+    void show_diff(ByteString const&);
 
-    DeprecatedString m_repo_root;
+    ByteString m_repo_root;
     RefPtr<GitFilesView> m_unstaged_files;
     RefPtr<GitFilesView> m_staged_files;
     RefPtr<GitRepo> m_git_repo;
diff --git a/Userland/DevTools/HackStudio/HackStudio.h b/Userland/DevTools/HackStudio/HackStudio.h
index 0dfabeec757..6923981e8fe 100644
--- a/Userland/DevTools/HackStudio/HackStudio.h
+++ b/Userland/DevTools/HackStudio/HackStudio.h
@@ -9,17 +9,17 @@
 #include "EditorWrapper.h"
 #include "LanguageClients/ConnectionsToServer.h"
 #include "Project.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibGUI/TextEditor.h>
 
 namespace HackStudio {
 
 GUI::TextEditor& current_editor();
-void open_file(DeprecatedString const&);
+void open_file(ByteString const&);
 RefPtr<EditorWrapper> current_editor_wrapper();
-void open_file(DeprecatedString const&, size_t line, size_t column);
+void open_file(ByteString const&, size_t line, size_t column);
 Project& project();
-DeprecatedString currently_open_file();
+ByteString currently_open_file();
 void set_current_editor_wrapper(RefPtr<EditorWrapper>);
 void update_editor_window_title();
 void for_each_open_file(Function<void(ProjectFile const&)>);
diff --git a/Userland/DevTools/HackStudio/HackStudioWidget.cpp b/Userland/DevTools/HackStudio/HackStudioWidget.cpp
index bd587422d65..4f1c859ee9d 100644
--- a/Userland/DevTools/HackStudio/HackStudioWidget.cpp
+++ b/Userland/DevTools/HackStudio/HackStudioWidget.cpp
@@ -80,7 +80,7 @@
 
 namespace HackStudio {
 
-ErrorOr<NonnullRefPtr<HackStudioWidget>> HackStudioWidget::create(DeprecatedString path_to_project)
+ErrorOr<NonnullRefPtr<HackStudioWidget>> HackStudioWidget::create(ByteString path_to_project)
 {
     auto widget = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) HackStudioWidget));
 
@@ -174,7 +174,7 @@ ErrorOr<NonnullRefPtr<HackStudioWidget>> HackStudioWidget::create(DeprecatedStri
                 return;
 
             if (event.event_path.starts_with(widget->project().root_path())) {
-                DeprecatedString relative_path = LexicalPath::relative_path(event.event_path, widget->project().root_path());
+                ByteString relative_path = LexicalPath::relative_path(event.event_path, widget->project().root_path());
                 widget->handle_external_file_deletion(relative_path);
             } else {
                 widget->handle_external_file_deletion(event.event_path);
@@ -213,7 +213,7 @@ void HackStudioWidget::on_action_tab_change()
     }
 }
 
-Vector<DeprecatedString> HackStudioWidget::read_recent_projects()
+Vector<ByteString> HackStudioWidget::read_recent_projects()
 {
     auto json = Config::read_string("HackStudio"sv, "Global"sv, "RecentProjects"sv);
     AK::JsonParser parser(json);
@@ -225,7 +225,7 @@ Vector<DeprecatedString> HackStudioWidget::read_recent_projects()
     if (!value.is_array())
         return {};
 
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
     for (auto& json_value : value.as_array().values()) {
         if (!json_value.is_string())
             return {};
@@ -235,7 +235,7 @@ Vector<DeprecatedString> HackStudioWidget::read_recent_projects()
     return paths;
 }
 
-void HackStudioWidget::open_project(DeprecatedString const& root_path)
+void HackStudioWidget::open_project(ByteString const& root_path)
 {
     if (warn_unsaved_changes("There are unsaved changes, do you want to save before closing current project?") == ContinueDecision::No)
         return;
@@ -280,20 +280,20 @@ void HackStudioWidget::open_project(DeprecatedString const& root_path)
     if (recent_projects.size() > recent_projects_history_size)
         recent_projects.shrink(recent_projects_history_size);
 
-    Config::write_string("HackStudio"sv, "Global"sv, "RecentProjects"sv, JsonArray(recent_projects).to_deprecated_string());
+    Config::write_string("HackStudio"sv, "Global"sv, "RecentProjects"sv, JsonArray(recent_projects).to_byte_string());
     update_recent_projects_submenu();
 }
 
-Vector<DeprecatedString> HackStudioWidget::selected_file_paths() const
+Vector<ByteString> HackStudioWidget::selected_file_paths() const
 {
-    Vector<DeprecatedString> files;
+    Vector<ByteString> files;
     m_project_tree_view->selection().for_each_index([&](const GUI::ModelIndex& index) {
-        DeprecatedString sub_path = index.data().as_string();
+        ByteString sub_path = index.data().as_string();
 
         GUI::ModelIndex parent_or_invalid = index.parent();
 
         while (parent_or_invalid.is_valid()) {
-            sub_path = DeprecatedString::formatted("{}/{}", parent_or_invalid.data().as_string(), sub_path);
+            sub_path = ByteString::formatted("{}/{}", parent_or_invalid.data().as_string(), sub_path);
 
             parent_or_invalid = parent_or_invalid.parent();
         }
@@ -303,9 +303,9 @@ Vector<DeprecatedString> HackStudioWidget::selected_file_paths() const
     return files;
 }
 
-bool HackStudioWidget::open_file(DeprecatedString const& full_filename, size_t line, size_t column)
+bool HackStudioWidget::open_file(ByteString const& full_filename, size_t line, size_t column)
 {
-    DeprecatedString filename = full_filename;
+    ByteString filename = full_filename;
     if (full_filename.starts_with(project().root_path())) {
         filename = LexicalPath::relative_path(full_filename, project().root_path());
     }
@@ -371,7 +371,7 @@ bool HackStudioWidget::open_file(DeprecatedString const& full_filename, size_t l
 
     set_edit_mode(EditMode::Text);
 
-    DeprecatedString relative_file_path = filename;
+    ByteString relative_file_path = filename;
     if (filename.starts_with(m_project->root_path()))
         relative_file_path = filename.substring(m_project->root_path().length() + 1);
 
@@ -390,16 +390,16 @@ bool HackStudioWidget::open_file(DeprecatedString const& full_filename, size_t l
     return true;
 }
 
-void HackStudioWidget::close_file_in_all_editors(DeprecatedString const& filename)
+void HackStudioWidget::close_file_in_all_editors(ByteString const& filename)
 {
     m_open_files.remove(filename);
     m_open_files_vector.remove_all_matching(
-        [&filename](DeprecatedString const& element) { return element == filename; });
+        [&filename](ByteString const& element) { return element == filename; });
 
     for (auto& editor_wrapper : m_all_editor_wrappers) {
         Editor& editor = editor_wrapper->editor();
-        DeprecatedString editor_file_path = editor.code_document().file_path();
-        DeprecatedString relative_editor_file_path = LexicalPath::relative_path(editor_file_path, project().root_path());
+        ByteString editor_file_path = editor.code_document().file_path();
+        ByteString relative_editor_file_path = LexicalPath::relative_path(editor_file_path, project().root_path());
 
         if (relative_editor_file_path == filename) {
             if (m_open_files_vector.is_empty()) {
@@ -515,7 +515,7 @@ ErrorOr<NonnullRefPtr<GUI::Menu>> HackStudioWidget::create_project_tree_view_con
     return project_tree_view_context_menu;
 }
 
-ErrorOr<NonnullRefPtr<GUI::Action>> HackStudioWidget::create_new_file_action(DeprecatedString const& label, DeprecatedString const& icon, DeprecatedString const& extension)
+ErrorOr<NonnullRefPtr<GUI::Action>> HackStudioWidget::create_new_file_action(ByteString const& label, ByteString const& icon, ByteString const& extension)
 {
     auto icon_no_shadow = TRY(Gfx::Bitmap::load_from_file(icon));
     return GUI::Action::create(label, icon_no_shadow, [this, extension](const GUI::Action&) {
@@ -523,34 +523,34 @@ ErrorOr<NonnullRefPtr<GUI::Action>> HackStudioWidget::create_new_file_action(Dep
         if (GUI::InputBox::show(window(), filename, "Enter a name:"sv, "New File"sv) != GUI::InputBox::ExecResult::OK)
             return;
 
-        if (!extension.is_empty() && !AK::StringUtils::ends_with(filename, DeprecatedString::formatted(".{}", extension), CaseSensitivity::CaseSensitive)) {
+        if (!extension.is_empty() && !AK::StringUtils::ends_with(filename, ByteString::formatted(".{}", extension), CaseSensitivity::CaseSensitive)) {
             filename = String::formatted("{}.{}", filename, extension).release_value_but_fixme_should_propagate_errors();
         }
 
         auto path_to_selected = selected_file_paths();
 
-        DeprecatedString filepath;
+        ByteString filepath;
 
         if (!path_to_selected.is_empty()) {
             VERIFY(FileSystem::exists(path_to_selected.first()));
 
             LexicalPath selected(path_to_selected.first());
 
-            DeprecatedString dir_path;
+            ByteString dir_path;
 
             if (FileSystem::is_directory(selected.string()))
                 dir_path = selected.string();
             else
                 dir_path = selected.dirname();
 
-            filepath = DeprecatedString::formatted("{}/", dir_path);
+            filepath = ByteString::formatted("{}/", dir_path);
         }
 
-        filepath = DeprecatedString::formatted("{}{}", filepath, filename);
+        filepath = ByteString::formatted("{}{}", filepath, filename);
 
         auto file_or_error = Core::File::open(filepath, Core::File::OpenMode::Write | Core::File::OpenMode::MustBeNew);
         if (file_or_error.is_error()) {
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to create '{}': {}", filepath, file_or_error.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to create '{}': {}", filepath, file_or_error.error()));
             return;
         }
         open_file(filepath);
@@ -570,7 +570,7 @@ ErrorOr<NonnullRefPtr<GUI::Action>> HackStudioWidget::create_new_directory_actio
         if (!path_to_selected.is_empty()) {
             LexicalPath selected(path_to_selected.first());
 
-            DeprecatedString dir_path;
+            ByteString dir_path;
 
             if (FileSystem::is_directory(selected.string()))
                 dir_path = selected.string();
@@ -580,7 +580,7 @@ ErrorOr<NonnullRefPtr<GUI::Action>> HackStudioWidget::create_new_directory_actio
             directory_name = String::formatted("{}/{}", dir_path, directory_name).release_value_but_fixme_should_propagate_errors();
         }
 
-        auto formatted_dir_name = LexicalPath::canonicalized_path(DeprecatedString::formatted("{}/{}", m_project->model().root_path(), directory_name));
+        auto formatted_dir_name = LexicalPath::canonicalized_path(ByteString::formatted("{}/{}", m_project->model().root_path(), directory_name));
         int rc = mkdir(formatted_dir_name.characters(), 0755);
         if (rc < 0) {
             GUI::MessageBox::show(window(), "Failed to create new directory"sv, "Error"sv, GUI::MessageBox::Type::Error);
@@ -620,7 +620,7 @@ NonnullRefPtr<GUI::Action> HackStudioWidget::create_copy_relative_path_action()
     auto copy_relative_path_action = GUI::Action::create("Copy &Relative Path", [this](const GUI::Action&) {
         auto paths = selected_file_paths();
         VERIFY(!paths.is_empty());
-        auto paths_string = DeprecatedString::join('\n', paths);
+        auto paths_string = ByteString::join('\n', paths);
         GUI::Clipboard::the().set_plain_text(paths_string);
     });
     copy_relative_path_action->set_enabled(true);
@@ -634,10 +634,10 @@ NonnullRefPtr<GUI::Action> HackStudioWidget::create_copy_full_path_action()
     auto copy_full_path_action = GUI::Action::create("Copy &Full Path", [this](const GUI::Action&) {
         auto paths = selected_file_paths();
         VERIFY(!paths.is_empty());
-        Vector<DeprecatedString> full_paths;
+        Vector<ByteString> full_paths;
         for (auto& path : paths)
             full_paths.append(get_absolute_path(path));
-        auto paths_string = DeprecatedString::join('\n', full_paths);
+        auto paths_string = ByteString::join('\n', full_paths);
         GUI::Clipboard::the().set_plain_text(paths_string);
     });
     copy_full_path_action->set_enabled(true);
@@ -653,12 +653,12 @@ NonnullRefPtr<GUI::Action> HackStudioWidget::create_delete_action()
         if (files.is_empty())
             return;
 
-        DeprecatedString message;
+        ByteString message;
         if (files.size() == 1) {
             LexicalPath file(files[0]);
-            message = DeprecatedString::formatted("Really remove \"{}\" from disk?", file.basename());
+            message = ByteString::formatted("Really remove \"{}\" from disk?", file.basename());
         } else {
-            message = DeprecatedString::formatted("Really remove \"{}\" files from disk?", files.size());
+            message = ByteString::formatted("Really remove \"{}\" files from disk?", files.size());
         }
 
         auto result = GUI::MessageBox::show(window(),
@@ -673,7 +673,7 @@ NonnullRefPtr<GUI::Action> HackStudioWidget::create_delete_action()
             struct stat st;
             if (lstat(file.characters(), &st) < 0) {
                 GUI::MessageBox::show(window(),
-                    DeprecatedString::formatted("lstat ({}) failed: {}", file, strerror(errno)),
+                    ByteString::formatted("lstat ({}) failed: {}", file, strerror(errno)),
                     "Removal Failed"sv,
                     GUI::MessageBox::Type::Error);
                 break;
@@ -684,12 +684,12 @@ NonnullRefPtr<GUI::Action> HackStudioWidget::create_delete_action()
                 auto& error = result.error();
                 if (is_directory) {
                     GUI::MessageBox::show(window(),
-                        DeprecatedString::formatted("Removing directory \"{}\" from the project failed: {}", file, error),
+                        ByteString::formatted("Removing directory \"{}\" from the project failed: {}", file, error),
                         "Removal Failed"sv,
                         GUI::MessageBox::Type::Error);
                 } else {
                     GUI::MessageBox::show(window(),
-                        DeprecatedString::formatted("Removing file \"{}\" from the project failed: {}", file, error),
+                        ByteString::formatted("Removing file \"{}\" from the project failed: {}", file, error),
                         "Removal Failed"sv,
                         GUI::MessageBox::Type::Error);
                 }
@@ -908,7 +908,7 @@ NonnullRefPtr<GUI::Action> HackStudioWidget::create_save_as_action()
         LexicalPath const old_path(old_filename);
 
         auto suggested_path = FileSystem::absolute_path(old_path.string()).release_value_but_fixme_should_propagate_errors();
-        Optional<DeprecatedString> save_path = GUI::FilePicker::get_save_filepath(window(),
+        Optional<ByteString> save_path = GUI::FilePicker::get_save_filepath(window(),
             old_filename.is_empty() ? "Untitled"sv : old_path.title(),
             old_filename.is_empty() ? "txt"sv : old_path.extension(),
             suggested_path);
@@ -916,7 +916,7 @@ NonnullRefPtr<GUI::Action> HackStudioWidget::create_save_as_action()
             return;
         }
 
-        DeprecatedString const relative_file_path = LexicalPath::relative_path(save_path.value(), m_project->root_path());
+        ByteString const relative_file_path = LexicalPath::relative_path(save_path.value(), m_project->root_path());
         if (current_editor_wrapper().filename().is_empty()) {
             current_editor_wrapper().set_filename(relative_file_path);
         } else {
@@ -1009,7 +1009,7 @@ ErrorOr<NonnullRefPtr<GUI::Action>> HackStudioWidget::create_debug_action()
     auto icon = TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/debug-run.png"sv));
     return GUI::Action::create("&Debug", icon, [this](auto&) {
         if (!FileSystem::exists(get_project_executable_path())) {
-            GUI::MessageBox::show(window(), DeprecatedString::formatted("Could not find file: {}. (did you build the project?)", get_project_executable_path()), "Error"sv, GUI::MessageBox::Type::Error);
+            GUI::MessageBox::show(window(), ByteString::formatted("Could not find file: {}. (did you build the project?)", get_project_executable_path()), "Error"sv, GUI::MessageBox::Type::Error);
             return;
         }
         if (Debugger::the().session()) {
@@ -1104,7 +1104,7 @@ void HackStudioWidget::initialize_debugger()
         });
 }
 
-DeprecatedString HackStudioWidget::get_full_path_of_serenity_source(DeprecatedString const& file)
+ByteString HackStudioWidget::get_full_path_of_serenity_source(ByteString const& file)
 {
     auto path_parts = LexicalPath(file).parts();
     while (!path_parts.is_empty() && path_parts[0] == "..") {
@@ -1114,10 +1114,10 @@ DeprecatedString HackStudioWidget::get_full_path_of_serenity_source(DeprecatedSt
     relative_path_builder.join('/', path_parts);
     constexpr char SERENITY_LIBS_PREFIX[] = "/usr/src/serenity";
     LexicalPath serenity_sources_base(SERENITY_LIBS_PREFIX);
-    return DeprecatedString::formatted("{}/{}", serenity_sources_base, relative_path_builder.to_deprecated_string());
+    return ByteString::formatted("{}/{}", serenity_sources_base, relative_path_builder.to_byte_string());
 }
 
-DeprecatedString HackStudioWidget::get_absolute_path(DeprecatedString const& path) const
+ByteString HackStudioWidget::get_absolute_path(ByteString const& path) const
 {
     // TODO: We can probably do a more specific condition here, something like
     // "if (file.starts_with("../Libraries/") || file.starts_with("../AK/"))"
@@ -1127,9 +1127,9 @@ DeprecatedString HackStudioWidget::get_absolute_path(DeprecatedString const& pat
     return m_project->to_absolute_path(path);
 }
 
-RefPtr<EditorWrapper> HackStudioWidget::get_editor_of_file(DeprecatedString const& filename)
+RefPtr<EditorWrapper> HackStudioWidget::get_editor_of_file(ByteString const& filename)
 {
-    DeprecatedString file_path = filename;
+    ByteString file_path = filename;
 
     if (filename.starts_with("../"sv)) {
         file_path = get_full_path_of_serenity_source(filename);
@@ -1140,19 +1140,19 @@ RefPtr<EditorWrapper> HackStudioWidget::get_editor_of_file(DeprecatedString cons
     return current_editor_wrapper();
 }
 
-DeprecatedString HackStudioWidget::get_project_executable_path() const
+ByteString HackStudioWidget::get_project_executable_path() const
 {
     // FIXME: Dumb heuristic ahead!
     // e.g /my/project => /my/project/project
     // TODO: Perhaps a Makefile rule for getting the value of $(PROGRAM) would be better?
-    return DeprecatedString::formatted("{}/{}", m_project->root_path(), LexicalPath::basename(m_project->root_path()));
+    return ByteString::formatted("{}/{}", m_project->root_path(), LexicalPath::basename(m_project->root_path()));
 }
 
 void HackStudioWidget::build()
 {
     auto result = m_project_builder->build(active_file());
     if (result.is_error()) {
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("{}", result.error()), "Build Failed"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(window(), ByteString::formatted("{}", result.error()), "Build Failed"sv, GUI::MessageBox::Type::Error);
         m_build_action->set_enabled(true);
         m_stop_action->set_enabled(false);
     } else {
@@ -1164,7 +1164,7 @@ void HackStudioWidget::run()
 {
     auto result = m_project_builder->run(active_file());
     if (result.is_error()) {
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("{}", result.error()), "Run Failed"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(window(), ByteString::formatted("{}", result.error()), "Run Failed"sv, GUI::MessageBox::Type::Error);
         m_run_action->set_enabled(true);
         m_stop_action->set_enabled(false);
     } else {
@@ -1202,7 +1202,7 @@ void HackStudioWidget::set_current_editor_wrapper(RefPtr<EditorWrapper> editor_w
     update_statusbar();
 }
 
-void HackStudioWidget::file_renamed(DeprecatedString const& old_name, DeprecatedString const& new_name)
+void HackStudioWidget::file_renamed(ByteString const& old_name, ByteString const& new_name)
 {
     auto editor_or_none = m_all_editor_wrappers.first_matching([&old_name](auto const& editor) {
         return editor->filename() == old_name;
@@ -1272,11 +1272,11 @@ void HackStudioWidget::configure_project_tree_view()
 void HackStudioWidget::create_open_files_view(GUI::Widget& parent)
 {
     m_open_files_view = parent.add<GUI::ListView>();
-    auto open_files_model = GUI::ItemListModel<DeprecatedString>::create(m_open_files_vector);
+    auto open_files_model = GUI::ItemListModel<ByteString>::create(m_open_files_vector);
     m_open_files_view->set_model(open_files_model);
 
     m_open_files_view->on_activation = [this](auto& index) {
-        open_file(index.data().to_deprecated_string());
+        open_file(index.data().to_byte_string());
     };
 }
 
@@ -1638,7 +1638,7 @@ void HackStudioWidget::update_statusbar()
 {
     StringBuilder builder;
     if (current_editor().has_selection()) {
-        DeprecatedString selected_text = current_editor().selected_text();
+        ByteString selected_text = current_editor().selected_text();
         auto word_count = current_editor().number_of_selected_words();
         builder.appendff("Selected: {:'d} {} ({:'d} {})", selected_text.length(), selected_text.length() == 1 ? "character" : "characters", word_count, word_count != 1 ? "words" : "word");
     }
@@ -1648,7 +1648,7 @@ void HackStudioWidget::update_statusbar()
     m_statusbar->set_text(2, String::formatted("Ln {:'d}  Col {:'d}", current_editor().cursor().line() + 1, current_editor().cursor().column()).release_value_but_fixme_should_propagate_errors());
 }
 
-void HackStudioWidget::handle_external_file_deletion(DeprecatedString const& filepath)
+void HackStudioWidget::handle_external_file_deletion(ByteString const& filepath)
 {
     close_file_in_all_editors(filepath);
 }
@@ -1686,7 +1686,7 @@ HackStudioWidget::~HackStudioWidget()
     stop_debugger_if_running();
 }
 
-HackStudioWidget::ContinueDecision HackStudioWidget::warn_unsaved_changes(DeprecatedString const& prompt)
+HackStudioWidget::ContinueDecision HackStudioWidget::warn_unsaved_changes(ByteString const& prompt)
 {
     if (!any_document_is_dirty())
         return ContinueDecision::Yes;
@@ -1747,13 +1747,13 @@ void HackStudioWidget::update_toolbar_actions()
 
 void HackStudioWidget::update_window_title()
 {
-    window()->set_title(DeprecatedString::formatted("{} - {} - Hack Studio", m_current_editor_wrapper->filename_title(), m_project->name()));
+    window()->set_title(ByteString::formatted("{} - {} - Hack Studio", m_current_editor_wrapper->filename_title(), m_project->name()));
     window()->set_modified(any_document_is_dirty());
 }
 
 void HackStudioWidget::update_current_editor_title()
 {
-    current_editor_tab_widget().set_tab_title(current_editor_wrapper(), String::from_deprecated_string(current_editor_wrapper().filename_title()).release_value_but_fixme_should_propagate_errors());
+    current_editor_tab_widget().set_tab_title(current_editor_wrapper(), String::from_byte_string(current_editor_wrapper().filename_title()).release_value_but_fixme_should_propagate_errors());
 }
 
 void HackStudioWidget::on_cursor_change()
@@ -1831,13 +1831,13 @@ ErrorOr<NonnullRefPtr<GUI::Action>> HackStudioWidget::create_open_project_config
         auto parent_directory = LexicalPath::dirname(Project::config_file_path);
         auto absolute_config_file_path = LexicalPath::absolute_path(m_project->root_path(), Project::config_file_path);
 
-        DeprecatedString formatted_error_string_holder;
+        ByteString formatted_error_string_holder;
         auto save_configuration_or_error = [&]() -> ErrorOr<void> {
             if (FileSystem::exists(absolute_config_file_path))
                 return {};
 
             if (FileSystem::exists(parent_directory) && !FileSystem::is_directory(parent_directory)) {
-                formatted_error_string_holder = DeprecatedString::formatted("Cannot create the '{}' directory because there is already a file with that name", parent_directory);
+                formatted_error_string_holder = ByteString::formatted("Cannot create the '{}' directory because there is already a file with that name", parent_directory);
                 return Error::from_string_view(formatted_error_string_holder.view());
             }
 
@@ -1854,7 +1854,7 @@ ErrorOr<NonnullRefPtr<GUI::Action>> HackStudioWidget::create_open_project_config
             return {};
         }();
         if (save_configuration_or_error.is_error()) {
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Saving configuration failed: {}.", save_configuration_or_error.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Saving configuration failed: {}.", save_configuration_or_error.error()));
             return;
         }
 
diff --git a/Userland/DevTools/HackStudio/HackStudioWidget.h b/Userland/DevTools/HackStudio/HackStudioWidget.h
index f31694c293d..0a92dbb6fef 100644
--- a/Userland/DevTools/HackStudio/HackStudioWidget.h
+++ b/Userland/DevTools/HackStudio/HackStudioWidget.h
@@ -37,11 +37,11 @@ class HackStudioWidget : public GUI::Widget {
     C_OBJECT_ABSTRACT(HackStudioWidget)
 
 public:
-    static ErrorOr<NonnullRefPtr<HackStudioWidget>> create(DeprecatedString path_to_project);
+    static ErrorOr<NonnullRefPtr<HackStudioWidget>> create(ByteString path_to_project);
     virtual ~HackStudioWidget() override;
 
-    bool open_file(DeprecatedString const& filename, size_t line = 0, size_t column = 0);
-    void close_file_in_all_editors(DeprecatedString const& filename);
+    bool open_file(ByteString const& filename, size_t line = 0, size_t column = 0);
+    void close_file_in_all_editors(ByteString const& filename);
 
     void update_actions();
     Project& project();
@@ -55,7 +55,7 @@ public:
     GUI::TabWidget& current_editor_tab_widget();
     GUI::TabWidget const& current_editor_tab_widget() const;
 
-    DeprecatedString const& active_file() const { return m_current_editor_wrapper->filename(); }
+    ByteString const& active_file() const { return m_current_editor_wrapper->filename(); }
     ErrorOr<void> initialize_menubar(GUI::Window&);
 
     Locator& locator()
@@ -68,7 +68,7 @@ public:
         No,
         Yes
     };
-    ContinueDecision warn_unsaved_changes(DeprecatedString const& prompt);
+    ContinueDecision warn_unsaved_changes(ByteString const& prompt);
 
     enum class Mode {
         Code,
@@ -80,7 +80,7 @@ public:
     void for_each_open_file(Function<void(ProjectFile const&)>);
     bool semantic_syntax_highlighting_is_enabled() const;
 
-    static Vector<DeprecatedString> read_recent_projects();
+    static Vector<ByteString> read_recent_projects();
 
     void update_current_editor_title();
     void update_window_title();
@@ -88,11 +88,11 @@ public:
 private:
     static constexpr size_t recent_projects_history_size = 15;
 
-    static DeprecatedString get_full_path_of_serenity_source(DeprecatedString const& file);
-    DeprecatedString get_absolute_path(DeprecatedString const&) const;
-    Vector<DeprecatedString> selected_file_paths() const;
+    static ByteString get_full_path_of_serenity_source(ByteString const& file);
+    ByteString get_absolute_path(ByteString const&) const;
+    Vector<ByteString> selected_file_paths() const;
 
-    void open_project(DeprecatedString const& root_path);
+    void open_project(ByteString const& root_path);
 
     enum class EditMode {
         Text,
@@ -102,7 +102,7 @@ private:
     void set_edit_mode(EditMode);
 
     ErrorOr<NonnullRefPtr<GUI::Menu>> create_project_tree_view_context_menu();
-    ErrorOr<NonnullRefPtr<GUI::Action>> create_new_file_action(DeprecatedString const& label, DeprecatedString const& icon, DeprecatedString const& extension);
+    ErrorOr<NonnullRefPtr<GUI::Action>> create_new_file_action(ByteString const& label, ByteString const& icon, ByteString const& extension);
     ErrorOr<NonnullRefPtr<GUI::Action>> create_new_directory_action();
     ErrorOr<NonnullRefPtr<GUI::Action>> create_open_selected_action();
     NonnullRefPtr<GUI::Action> create_delete_action();
@@ -133,15 +133,15 @@ private:
 
     void add_new_editor_tab_widget(GUI::Widget& parent);
     void add_new_editor(GUI::TabWidget& parent);
-    RefPtr<EditorWrapper> get_editor_of_file(DeprecatedString const& filename);
-    DeprecatedString get_project_executable_path() const;
+    RefPtr<EditorWrapper> get_editor_of_file(ByteString const& filename);
+    ByteString get_project_executable_path() const;
 
     void on_action_tab_change();
     void reveal_action_tab(GUI::Widget&);
     void initialize_debugger();
     void update_statusbar();
 
-    void handle_external_file_deletion(DeprecatedString const& filepath);
+    void handle_external_file_deletion(ByteString const& filepath);
     void stop_debugger_if_running();
     void close_current_project();
 
@@ -167,11 +167,11 @@ private:
     void update_tree_view();
     void update_toolbar_actions();
     void on_cursor_change();
-    void file_renamed(DeprecatedString const& old_name, DeprecatedString const& new_name);
+    void file_renamed(ByteString const& old_name, ByteString const& new_name);
     bool save_file_changes();
 
     struct ProjectLocation {
-        DeprecatedString filename;
+        ByteString filename;
         size_t line { 0 };
         size_t column { 0 };
     };
@@ -184,9 +184,9 @@ private:
     Vector<NonnullRefPtr<GUI::TabWidget>> m_all_editor_tab_widgets;
     RefPtr<GUI::TabWidget> m_current_editor_tab_widget;
 
-    HashMap<DeprecatedString, NonnullRefPtr<ProjectFile>> m_open_files;
+    HashMap<ByteString, NonnullRefPtr<ProjectFile>> m_open_files;
     RefPtr<Core::FileWatcher> m_file_watcher;
-    Vector<DeprecatedString> m_open_files_vector; // NOTE: This contains the keys from m_open_files and m_file_watchers
+    Vector<ByteString> m_open_files_vector; // NOTE: This contains the keys from m_open_files and m_file_watchers
 
     OwnPtr<Project> m_project;
 
diff --git a/Userland/DevTools/HackStudio/LanguageClient.cpp b/Userland/DevTools/HackStudio/LanguageClient.cpp
index a28eb13318d..54c4f9593ad 100644
--- a/Userland/DevTools/HackStudio/LanguageClient.cpp
+++ b/Userland/DevTools/HackStudio/LanguageClient.cpp
@@ -8,7 +8,7 @@
 #include "HackStudio.h"
 #include "ProjectDeclarations.h"
 #include "ToDoEntries.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <LibGUI/Notification.h>
 
@@ -32,7 +32,7 @@ void ConnectionToServer::declaration_location(CodeComprehension::ProjectLocation
     m_current_language_client->declaration_found(location.file, location.line, location.column);
 }
 
-void ConnectionToServer::parameters_hint_result(Vector<DeprecatedString> const& params, int argument_index)
+void ConnectionToServer::parameters_hint_result(Vector<ByteString> const& params, int argument_index)
 {
     if (!m_current_language_client) {
         dbgln("Language Server connection has no attached language client");
@@ -60,35 +60,35 @@ void ConnectionToServer::die()
     m_wrapper->on_crash();
 }
 
-void LanguageClient::open_file(DeprecatedString const& path, int fd)
+void LanguageClient::open_file(ByteString const& path, int fd)
 {
     if (!m_connection_wrapper.connection())
         return;
     m_connection_wrapper.connection()->async_file_opened(path, fd);
 }
 
-void LanguageClient::set_file_content(DeprecatedString const& path, DeprecatedString const& content)
+void LanguageClient::set_file_content(ByteString const& path, ByteString const& content)
 {
     if (!m_connection_wrapper.connection())
         return;
     m_connection_wrapper.connection()->async_set_file_content(path, content);
 }
 
-void LanguageClient::insert_text(DeprecatedString const& path, DeprecatedString const& text, size_t line, size_t column)
+void LanguageClient::insert_text(ByteString const& path, ByteString const& text, size_t line, size_t column)
 {
     if (!m_connection_wrapper.connection())
         return;
     m_connection_wrapper.connection()->async_file_edit_insert_text(path, text, line, column);
 }
 
-void LanguageClient::remove_text(DeprecatedString const& path, size_t from_line, size_t from_column, size_t to_line, size_t to_column)
+void LanguageClient::remove_text(ByteString const& path, size_t from_line, size_t from_column, size_t to_line, size_t to_column)
 {
     if (!m_connection_wrapper.connection())
         return;
     m_connection_wrapper.connection()->async_file_edit_remove_text(path, from_line, from_column, to_line, to_column);
 }
 
-void LanguageClient::request_autocomplete(DeprecatedString const& path, size_t cursor_line, size_t cursor_column)
+void LanguageClient::request_autocomplete(ByteString const& path, size_t cursor_line, size_t cursor_column)
 {
     if (!m_connection_wrapper.connection())
         return;
@@ -118,19 +118,19 @@ bool LanguageClient::is_active_client() const
     return m_connection_wrapper.connection()->active_client() == this;
 }
 
-HashMap<DeprecatedString, NonnullOwnPtr<ConnectionToServerWrapper>> ConnectionToServerInstances::s_instance_for_language;
+HashMap<ByteString, NonnullOwnPtr<ConnectionToServerWrapper>> ConnectionToServerInstances::s_instance_for_language;
 
-void ConnectionToServer::declarations_in_document(DeprecatedString const& filename, Vector<CodeComprehension::Declaration> const& declarations)
+void ConnectionToServer::declarations_in_document(ByteString const& filename, Vector<CodeComprehension::Declaration> const& declarations)
 {
     ProjectDeclarations::the().set_declared_symbols(filename, declarations);
 }
 
-void ConnectionToServer::todo_entries_in_document(DeprecatedString const& filename, Vector<CodeComprehension::TodoEntry> const& todo_entries)
+void ConnectionToServer::todo_entries_in_document(ByteString const& filename, Vector<CodeComprehension::TodoEntry> const& todo_entries)
 {
     ToDoEntries::the().set_entries(filename, move(todo_entries));
 }
 
-void LanguageClient::search_declaration(DeprecatedString const& path, size_t line, size_t column)
+void LanguageClient::search_declaration(ByteString const& path, size_t line, size_t column)
 {
     if (!m_connection_wrapper.connection())
         return;
@@ -138,7 +138,7 @@ void LanguageClient::search_declaration(DeprecatedString const& path, size_t lin
     m_connection_wrapper.connection()->async_find_declaration(CodeComprehension::ProjectLocation { path, line, column });
 }
 
-void LanguageClient::get_parameters_hint(DeprecatedString const& path, size_t line, size_t column)
+void LanguageClient::get_parameters_hint(ByteString const& path, size_t line, size_t column)
 {
     if (!m_connection_wrapper.connection())
         return;
@@ -146,7 +146,7 @@ void LanguageClient::get_parameters_hint(DeprecatedString const& path, size_t li
     m_connection_wrapper.connection()->async_get_parameters_hint(CodeComprehension::ProjectLocation { path, line, column });
 }
 
-void LanguageClient::get_tokens_info(DeprecatedString const& filename)
+void LanguageClient::get_tokens_info(ByteString const& filename)
 {
     if (!m_connection_wrapper.connection())
         return;
@@ -154,7 +154,7 @@ void LanguageClient::get_tokens_info(DeprecatedString const& filename)
     m_connection_wrapper.connection()->async_get_tokens_info(filename);
 }
 
-void LanguageClient::declaration_found(DeprecatedString const& file, size_t line, size_t column) const
+void LanguageClient::declaration_found(ByteString const& file, size_t line, size_t column) const
 {
     if (!on_declaration_found) {
         dbgln("on_declaration_found callback is not set");
@@ -163,7 +163,7 @@ void LanguageClient::declaration_found(DeprecatedString const& file, size_t line
     on_declaration_found(file, line, column);
 }
 
-void LanguageClient::parameters_hint_result(Vector<DeprecatedString> const& params, size_t argument_index) const
+void LanguageClient::parameters_hint_result(Vector<ByteString> const& params, size_t argument_index) const
 {
     if (!on_function_parameters_hint_result) {
         dbgln("on_function_parameters_hint_result callback is not set");
@@ -172,17 +172,17 @@ void LanguageClient::parameters_hint_result(Vector<DeprecatedString> const& para
     on_function_parameters_hint_result(params, argument_index);
 }
 
-void ConnectionToServerInstances::set_instance_for_language(DeprecatedString const& language_name, NonnullOwnPtr<ConnectionToServerWrapper>&& connection_wrapper)
+void ConnectionToServerInstances::set_instance_for_language(ByteString const& language_name, NonnullOwnPtr<ConnectionToServerWrapper>&& connection_wrapper)
 {
     s_instance_for_language.set(language_name, move(connection_wrapper));
 }
 
-void ConnectionToServerInstances::remove_instance_for_language(DeprecatedString const& language_name)
+void ConnectionToServerInstances::remove_instance_for_language(ByteString const& language_name)
 {
     s_instance_for_language.remove(language_name);
 }
 
-ConnectionToServerWrapper* ConnectionToServerInstances::get_instance_wrapper(DeprecatedString const& language_name)
+ConnectionToServerWrapper* ConnectionToServerInstances::get_instance_wrapper(ByteString const& language_name)
 {
     if (auto instance = s_instance_for_language.get(language_name); instance.has_value()) {
         return const_cast<ConnectionToServerWrapper*>(instance.value());
@@ -225,7 +225,7 @@ void ConnectionToServerWrapper::show_crash_notification() const
     notification->show();
 }
 
-ConnectionToServerWrapper::ConnectionToServerWrapper(DeprecatedString const& language_name, Function<NonnullRefPtr<ConnectionToServer>()> connection_creator)
+ConnectionToServerWrapper::ConnectionToServerWrapper(ByteString const& language_name, Function<NonnullRefPtr<ConnectionToServer>()> connection_creator)
     : m_language(Syntax::language_from_name(language_name).value())
     , m_connection_creator(move(connection_creator))
 {
diff --git a/Userland/DevTools/HackStudio/LanguageClient.h b/Userland/DevTools/HackStudio/LanguageClient.h
index a1d5fa15ed7..b2f1dcb573a 100644
--- a/Userland/DevTools/HackStudio/LanguageClient.h
+++ b/Userland/DevTools/HackStudio/LanguageClient.h
@@ -31,7 +31,7 @@ class ConnectionToServer
     friend class ConnectionToServerWrapper;
 
 public:
-    ConnectionToServer(NonnullOwnPtr<Core::LocalSocket> socket, DeprecatedString const& project_path)
+    ConnectionToServer(NonnullOwnPtr<Core::LocalSocket> socket, ByteString const& project_path)
         : IPC::ConnectionToServer<LanguageClientEndpoint, LanguageServerEndpoint>(*this, move(socket))
     {
         m_project_path = project_path;
@@ -39,7 +39,7 @@ public:
     }
 
     WeakPtr<LanguageClient> language_client() { return m_current_language_client; }
-    DeprecatedString const& project_path() const { return m_project_path; }
+    ByteString const& project_path() const { return m_project_path; }
 
     virtual void die() override;
 
@@ -48,13 +48,13 @@ public:
 protected:
     virtual void auto_complete_suggestions(Vector<CodeComprehension::AutocompleteResultEntry> const&) override;
     virtual void declaration_location(CodeComprehension::ProjectLocation const&) override;
-    virtual void declarations_in_document(DeprecatedString const&, Vector<CodeComprehension::Declaration> const&) override;
-    virtual void todo_entries_in_document(DeprecatedString const&, Vector<CodeComprehension::TodoEntry> const&) override;
-    virtual void parameters_hint_result(Vector<DeprecatedString> const&, int index) override;
+    virtual void declarations_in_document(ByteString const&, Vector<CodeComprehension::Declaration> const&) override;
+    virtual void todo_entries_in_document(ByteString const&, Vector<CodeComprehension::TodoEntry> const&) override;
+    virtual void parameters_hint_result(Vector<ByteString> const&, int index) override;
     virtual void tokens_info_result(Vector<CodeComprehension::TokenInfo> const&) override;
     void set_wrapper(ConnectionToServerWrapper& wrapper) { m_wrapper = &wrapper; }
 
-    DeprecatedString m_project_path;
+    ByteString m_project_path;
     WeakPtr<LanguageClient> m_current_language_client;
     ConnectionToServerWrapper* m_wrapper { nullptr };
 };
@@ -63,11 +63,11 @@ class ConnectionToServerWrapper {
     AK_MAKE_NONCOPYABLE(ConnectionToServerWrapper);
 
 public:
-    explicit ConnectionToServerWrapper(DeprecatedString const& language_name, Function<NonnullRefPtr<ConnectionToServer>()> connection_creator);
+    explicit ConnectionToServerWrapper(ByteString const& language_name, Function<NonnullRefPtr<ConnectionToServer>()> connection_creator);
     ~ConnectionToServerWrapper() = default;
 
     template<typename LanguageServerType>
-    static ConnectionToServerWrapper& get_or_create(DeprecatedString const& project_path);
+    static ConnectionToServerWrapper& get_or_create(ByteString const& project_path);
 
     Syntax::Language language() const { return m_language; }
     ConnectionToServer* connection();
@@ -93,13 +93,13 @@ private:
 
 class ConnectionToServerInstances {
 public:
-    static void set_instance_for_language(DeprecatedString const& language_name, NonnullOwnPtr<ConnectionToServerWrapper>&& connection_wrapper);
-    static void remove_instance_for_language(DeprecatedString const& language_name);
+    static void set_instance_for_language(ByteString const& language_name, NonnullOwnPtr<ConnectionToServerWrapper>&& connection_wrapper);
+    static void remove_instance_for_language(ByteString const& language_name);
 
-    static ConnectionToServerWrapper* get_instance_wrapper(DeprecatedString const& language_name);
+    static ConnectionToServerWrapper* get_instance_wrapper(ByteString const& language_name);
 
 private:
-    static HashMap<DeprecatedString, NonnullOwnPtr<ConnectionToServerWrapper>> s_instance_for_language;
+    static HashMap<ByteString, NonnullOwnPtr<ConnectionToServerWrapper>> s_instance_for_language;
 };
 
 class LanguageClient : public Weakable<LanguageClient> {
@@ -128,23 +128,23 @@ public:
     Syntax::Language language() const { return m_connection_wrapper.language(); }
     void set_active_client();
     bool is_active_client() const;
-    virtual void open_file(DeprecatedString const& path, int fd);
-    virtual void set_file_content(DeprecatedString const& path, DeprecatedString const& content);
-    virtual void insert_text(DeprecatedString const& path, DeprecatedString const& text, size_t line, size_t column);
-    virtual void remove_text(DeprecatedString const& path, size_t from_line, size_t from_column, size_t to_line, size_t to_column);
-    virtual void request_autocomplete(DeprecatedString const& path, size_t cursor_line, size_t cursor_column);
-    virtual void search_declaration(DeprecatedString const& path, size_t line, size_t column);
-    virtual void get_parameters_hint(DeprecatedString const& path, size_t line, size_t column);
-    virtual void get_tokens_info(DeprecatedString const& filename);
+    virtual void open_file(ByteString const& path, int fd);
+    virtual void set_file_content(ByteString const& path, ByteString const& content);
+    virtual void insert_text(ByteString const& path, ByteString const& text, size_t line, size_t column);
+    virtual void remove_text(ByteString const& path, size_t from_line, size_t from_column, size_t to_line, size_t to_column);
+    virtual void request_autocomplete(ByteString const& path, size_t cursor_line, size_t cursor_column);
+    virtual void search_declaration(ByteString const& path, size_t line, size_t column);
+    virtual void get_parameters_hint(ByteString const& path, size_t line, size_t column);
+    virtual void get_tokens_info(ByteString const& filename);
 
     void provide_autocomplete_suggestions(Vector<CodeComprehension::AutocompleteResultEntry> const&) const;
-    void declaration_found(DeprecatedString const& file, size_t line, size_t column) const;
-    void parameters_hint_result(Vector<DeprecatedString> const& params, size_t argument_index) const;
+    void declaration_found(ByteString const& file, size_t line, size_t column) const;
+    void parameters_hint_result(Vector<ByteString> const& params, size_t argument_index) const;
 
     // Callbacks that get called when the result of a language server query is ready
     Function<void(Vector<CodeComprehension::AutocompleteResultEntry>)> on_autocomplete_suggestions;
-    Function<void(DeprecatedString const&, size_t, size_t)> on_declaration_found;
-    Function<void(Vector<DeprecatedString> const&, size_t)> on_function_parameters_hint_result;
+    Function<void(ByteString const&, size_t, size_t)> on_declaration_found;
+    Function<void(Vector<ByteString> const&, size_t)> on_function_parameters_hint_result;
     Function<void(Vector<CodeComprehension::TokenInfo> const&)> on_tokens_info_result;
 
 private:
@@ -153,13 +153,13 @@ private:
 };
 
 template<typename ConnectionToServerT>
-static inline NonnullOwnPtr<LanguageClient> get_language_client(DeprecatedString const& project_path)
+static inline NonnullOwnPtr<LanguageClient> get_language_client(ByteString const& project_path)
 {
     return make<LanguageClient>(ConnectionToServerWrapper::get_or_create<ConnectionToServerT>(project_path));
 }
 
 template<typename LanguageServerType>
-ConnectionToServerWrapper& ConnectionToServerWrapper::get_or_create(DeprecatedString const& project_path)
+ConnectionToServerWrapper& ConnectionToServerWrapper::get_or_create(ByteString const& project_path)
 {
     auto* wrapper = ConnectionToServerInstances::get_instance_wrapper(LanguageServerType::language_name());
     if (wrapper)
diff --git a/Userland/DevTools/HackStudio/LanguageClients/ConnectionsToServer.h b/Userland/DevTools/HackStudio/LanguageClients/ConnectionsToServer.h
index 34335169140..a511f5e7387 100644
--- a/Userland/DevTools/HackStudio/LanguageClients/ConnectionsToServer.h
+++ b/Userland/DevTools/HackStudio/LanguageClients/ConnectionsToServer.h
@@ -12,22 +12,22 @@
 #include <DevTools/HackStudio/LanguageServers/LanguageServerEndpoint.h>
 #include <LibIPC/ConnectionToServer.h>
 
-#define LANGUAGE_CLIENT(language_name_, socket_name)                                                      \
-    namespace language_name_ {                                                                            \
-    class ConnectionToServer final : public HackStudio::ConnectionToServer {                              \
-        IPC_CLIENT_CONNECTION(ConnectionToServer, "/tmp/session/%sid/portal/language/" socket_name)       \
-    public:                                                                                               \
-        static char const* language_name()                                                                \
-        {                                                                                                 \
-            return #language_name_;                                                                       \
-        }                                                                                                 \
-                                                                                                          \
-    private:                                                                                              \
-        ConnectionToServer(NonnullOwnPtr<Core::LocalSocket> socket, DeprecatedString const& project_path) \
-            : HackStudio::ConnectionToServer(move(socket), project_path)                                  \
-        {                                                                                                 \
-        }                                                                                                 \
-    };                                                                                                    \
+#define LANGUAGE_CLIENT(language_name_, socket_name)                                                \
+    namespace language_name_ {                                                                      \
+    class ConnectionToServer final : public HackStudio::ConnectionToServer {                        \
+        IPC_CLIENT_CONNECTION(ConnectionToServer, "/tmp/session/%sid/portal/language/" socket_name) \
+    public:                                                                                         \
+        static char const* language_name()                                                          \
+        {                                                                                           \
+            return #language_name_;                                                                 \
+        }                                                                                           \
+                                                                                                    \
+    private:                                                                                        \
+        ConnectionToServer(NonnullOwnPtr<Core::LocalSocket> socket, ByteString const& project_path) \
+            : HackStudio::ConnectionToServer(move(socket), project_path)                            \
+        {                                                                                           \
+        }                                                                                           \
+    };                                                                                              \
     }
 
 namespace LanguageClients {
diff --git a/Userland/DevTools/HackStudio/LanguageServers/ConnectionFromClient.cpp b/Userland/DevTools/HackStudio/LanguageServers/ConnectionFromClient.cpp
index fa3d664e27c..878b7ed7ec2 100644
--- a/Userland/DevTools/HackStudio/LanguageServers/ConnectionFromClient.cpp
+++ b/Userland/DevTools/HackStudio/LanguageServers/ConnectionFromClient.cpp
@@ -26,7 +26,7 @@ void ConnectionFromClient::die()
     exit(0);
 }
 
-void ConnectionFromClient::greet(DeprecatedString const& project_root)
+void ConnectionFromClient::greet(ByteString const& project_root)
 {
     m_filedb.set_project_root(project_root);
     if (unveil(project_root.characters(), "r") < 0) {
@@ -39,7 +39,7 @@ void ConnectionFromClient::greet(DeprecatedString const& project_root)
     }
 }
 
-void ConnectionFromClient::file_opened(DeprecatedString const& filename, IPC::File const& file)
+void ConnectionFromClient::file_opened(ByteString const& filename, IPC::File const& file)
 {
     if (m_filedb.is_open(filename)) {
         return;
@@ -48,7 +48,7 @@ void ConnectionFromClient::file_opened(DeprecatedString const& filename, IPC::Fi
     m_autocomplete_engine->file_opened(filename);
 }
 
-void ConnectionFromClient::file_edit_insert_text(DeprecatedString const& filename, DeprecatedString const& text, i32 start_line, i32 start_column)
+void ConnectionFromClient::file_edit_insert_text(ByteString const& filename, ByteString const& text, i32 start_line, i32 start_column)
 {
     dbgln_if(LANGUAGE_SERVER_DEBUG, "InsertText for file: {}", filename);
     dbgln_if(LANGUAGE_SERVER_DEBUG, "Text: {}", text);
@@ -57,7 +57,7 @@ void ConnectionFromClient::file_edit_insert_text(DeprecatedString const& filenam
     m_autocomplete_engine->on_edit(filename);
 }
 
-void ConnectionFromClient::file_edit_remove_text(DeprecatedString const& filename, i32 start_line, i32 start_column, i32 end_line, i32 end_column)
+void ConnectionFromClient::file_edit_remove_text(ByteString const& filename, i32 start_line, i32 start_column, i32 end_line, i32 end_column)
 {
     dbgln_if(LANGUAGE_SERVER_DEBUG, "RemoveText for file: {}", filename);
     dbgln_if(LANGUAGE_SERVER_DEBUG, "[{}:{} - {}:{}]", start_line, start_column, end_line, end_column);
@@ -80,7 +80,7 @@ void ConnectionFromClient::auto_complete_suggestions(CodeComprehension::ProjectL
     async_auto_complete_suggestions(move(suggestions));
 }
 
-void ConnectionFromClient::set_file_content(DeprecatedString const& filename, DeprecatedString const& content)
+void ConnectionFromClient::set_file_content(ByteString const& filename, ByteString const& content)
 {
     dbgln_if(LANGUAGE_SERVER_DEBUG, "SetFileContent: {}", filename);
     auto document = m_filedb.get_document(filename);
@@ -139,7 +139,7 @@ void ConnectionFromClient::get_parameters_hint(CodeComprehension::ProjectLocatio
     async_parameters_hint_result(params->params, params->current_index);
 }
 
-void ConnectionFromClient::get_tokens_info(DeprecatedString const& filename)
+void ConnectionFromClient::get_tokens_info(ByteString const& filename)
 {
     dbgln_if(LANGUAGE_SERVER_DEBUG, "GetTokenInfo: {}", filename);
     auto document = m_filedb.get_document(filename);
diff --git a/Userland/DevTools/HackStudio/LanguageServers/ConnectionFromClient.h b/Userland/DevTools/HackStudio/LanguageServers/ConnectionFromClient.h
index 59affb06c20..9498e929100 100644
--- a/Userland/DevTools/HackStudio/LanguageServers/ConnectionFromClient.h
+++ b/Userland/DevTools/HackStudio/LanguageServers/ConnectionFromClient.h
@@ -27,15 +27,15 @@ public:
     virtual void die() override;
 
 protected:
-    virtual void greet(DeprecatedString const&) override;
-    virtual void file_opened(DeprecatedString const&, IPC::File const&) override;
-    virtual void file_edit_insert_text(DeprecatedString const&, DeprecatedString const&, i32, i32) override;
-    virtual void file_edit_remove_text(DeprecatedString const&, i32, i32, i32, i32) override;
-    virtual void set_file_content(DeprecatedString const&, DeprecatedString const&) override;
+    virtual void greet(ByteString const&) override;
+    virtual void file_opened(ByteString const&, IPC::File const&) override;
+    virtual void file_edit_insert_text(ByteString const&, ByteString const&, i32, i32) override;
+    virtual void file_edit_remove_text(ByteString const&, i32, i32, i32, i32) override;
+    virtual void set_file_content(ByteString const&, ByteString const&) override;
     virtual void auto_complete_suggestions(CodeComprehension::ProjectLocation const&) override;
     virtual void find_declaration(CodeComprehension::ProjectLocation const&) override;
     virtual void get_parameters_hint(CodeComprehension::ProjectLocation const&) override;
-    virtual void get_tokens_info(DeprecatedString const&) override;
+    virtual void get_tokens_info(ByteString const&) override;
 
     FileDB m_filedb;
     OwnPtr<CodeComprehension::CodeComprehensionEngine> m_autocomplete_engine;
diff --git a/Userland/DevTools/HackStudio/LanguageServers/Cpp/ConnectionFromClient.h b/Userland/DevTools/HackStudio/LanguageServers/Cpp/ConnectionFromClient.h
index 360788c91ae..1b7671e6e3f 100644
--- a/Userland/DevTools/HackStudio/LanguageServers/Cpp/ConnectionFromClient.h
+++ b/Userland/DevTools/HackStudio/LanguageServers/Cpp/ConnectionFromClient.h
@@ -19,10 +19,10 @@ private:
         : LanguageServers::ConnectionFromClient(move(socket))
     {
         m_autocomplete_engine = adopt_own(*new CodeComprehension::Cpp::CppComprehensionEngine(m_filedb));
-        m_autocomplete_engine->set_declarations_of_document_callback = [this](DeprecatedString const& filename, Vector<CodeComprehension::Declaration>&& declarations) {
+        m_autocomplete_engine->set_declarations_of_document_callback = [this](ByteString const& filename, Vector<CodeComprehension::Declaration>&& declarations) {
             async_declarations_in_document(filename, move(declarations));
         };
-        m_autocomplete_engine->set_todo_entries_of_document_callback = [this](DeprecatedString const& filename, Vector<CodeComprehension::TodoEntry>&& todo_entries) {
+        m_autocomplete_engine->set_todo_entries_of_document_callback = [this](ByteString const& filename, Vector<CodeComprehension::TodoEntry>&& todo_entries) {
             async_todo_entries_in_document(filename, move(todo_entries));
         };
     }
diff --git a/Userland/DevTools/HackStudio/LanguageServers/FileDB.cpp b/Userland/DevTools/HackStudio/LanguageServers/FileDB.cpp
index 5bfb6448c89..831abe43c7d 100644
--- a/Userland/DevTools/HackStudio/LanguageServers/FileDB.cpp
+++ b/Userland/DevTools/HackStudio/LanguageServers/FileDB.cpp
@@ -13,7 +13,7 @@
 
 namespace LanguageServers {
 
-RefPtr<const GUI::TextDocument> FileDB::get_document(DeprecatedString const& filename) const
+RefPtr<const GUI::TextDocument> FileDB::get_document(ByteString const& filename) const
 {
     auto absolute_path = to_absolute_path(filename);
     auto document_optional = m_open_files.get(absolute_path);
@@ -23,7 +23,7 @@ RefPtr<const GUI::TextDocument> FileDB::get_document(DeprecatedString const& fil
     return *document_optional.value();
 }
 
-RefPtr<GUI::TextDocument> FileDB::get_document(DeprecatedString const& filename)
+RefPtr<GUI::TextDocument> FileDB::get_document(ByteString const& filename)
 {
     auto document = reinterpret_cast<FileDB const*>(this)->get_document(filename);
     if (document.is_null())
@@ -31,7 +31,7 @@ RefPtr<GUI::TextDocument> FileDB::get_document(DeprecatedString const& filename)
     return adopt_ref(*const_cast<GUI::TextDocument*>(document.leak_ref()));
 }
 
-Optional<DeprecatedString> FileDB::get_or_read_from_filesystem(StringView filename) const
+Optional<ByteString> FileDB::get_or_read_from_filesystem(StringView filename) const
 {
     auto absolute_path = to_absolute_path(filename);
     auto document = get_document(absolute_path);
@@ -46,12 +46,12 @@ Optional<DeprecatedString> FileDB::get_or_read_from_filesystem(StringView filena
     return document_or_error.value()->text();
 }
 
-bool FileDB::is_open(DeprecatedString const& filename) const
+bool FileDB::is_open(ByteString const& filename) const
 {
     return m_open_files.contains(to_absolute_path(filename));
 }
 
-bool FileDB::add(DeprecatedString const& filename, int fd)
+bool FileDB::add(ByteString const& filename, int fd)
 {
     auto document_or_error = create_from_fd(fd);
     if (document_or_error.is_error()) {
@@ -63,17 +63,17 @@ bool FileDB::add(DeprecatedString const& filename, int fd)
     return true;
 }
 
-DeprecatedString FileDB::to_absolute_path(DeprecatedString const& filename) const
+ByteString FileDB::to_absolute_path(ByteString const& filename) const
 {
     if (LexicalPath { filename }.is_absolute()) {
         return filename;
     }
     if (!m_project_root.has_value())
         return filename;
-    return LexicalPath { DeprecatedString::formatted("{}/{}", *m_project_root, filename) }.string();
+    return LexicalPath { ByteString::formatted("{}/{}", *m_project_root, filename) }.string();
 }
 
-ErrorOr<NonnullRefPtr<GUI::TextDocument>> FileDB::create_from_filesystem(DeprecatedString const& filename) const
+ErrorOr<NonnullRefPtr<GUI::TextDocument>> FileDB::create_from_filesystem(ByteString const& filename) const
 {
     auto file = TRY(Core::File::open(to_absolute_path(filename), Core::File::OpenMode::Read));
     return create_from_file(move(file));
@@ -110,7 +110,7 @@ ErrorOr<NonnullRefPtr<GUI::TextDocument>> FileDB::create_from_file(NonnullOwnPtr
     return document;
 }
 
-void FileDB::on_file_edit_insert_text(DeprecatedString const& filename, DeprecatedString const& inserted_text, size_t start_line, size_t start_column)
+void FileDB::on_file_edit_insert_text(ByteString const& filename, ByteString const& inserted_text, size_t start_line, size_t start_column)
 {
     VERIFY(is_open(filename));
     auto document = get_document(filename);
@@ -121,7 +121,7 @@ void FileDB::on_file_edit_insert_text(DeprecatedString const& filename, Deprecat
     dbgln_if(FILE_CONTENT_DEBUG, "{}", document->text());
 }
 
-void FileDB::on_file_edit_remove_text(DeprecatedString const& filename, size_t start_line, size_t start_column, size_t end_line, size_t end_column)
+void FileDB::on_file_edit_remove_text(ByteString const& filename, size_t start_line, size_t start_column, size_t end_line, size_t end_column)
 {
     // TODO: If file is not open - need to get its contents
     // Otherwise- somehow verify that respawned language server is synced with all file contents
@@ -138,7 +138,7 @@ void FileDB::on_file_edit_remove_text(DeprecatedString const& filename, size_t s
     dbgln_if(FILE_CONTENT_DEBUG, "{}", document->text());
 }
 
-RefPtr<GUI::TextDocument> FileDB::create_with_content(DeprecatedString const& content)
+RefPtr<GUI::TextDocument> FileDB::create_with_content(ByteString const& content)
 {
     StringView content_view(content);
     auto document = GUI::TextDocument::create(&s_default_document_client);
@@ -146,7 +146,7 @@ RefPtr<GUI::TextDocument> FileDB::create_with_content(DeprecatedString const& co
     return document;
 }
 
-bool FileDB::add(DeprecatedString const& filename, DeprecatedString const& content)
+bool FileDB::add(ByteString const& filename, ByteString const& content)
 {
     auto document = create_with_content(content);
     if (!document) {
diff --git a/Userland/DevTools/HackStudio/LanguageServers/FileDB.h b/Userland/DevTools/HackStudio/LanguageServers/FileDB.h
index 35b743306d0..96221e6fdfa 100644
--- a/Userland/DevTools/HackStudio/LanguageServers/FileDB.h
+++ b/Userland/DevTools/HackStudio/LanguageServers/FileDB.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/NonnullRefPtr.h>
 #include <LibCodeComprehension/FileDB.h>
@@ -17,28 +17,28 @@ namespace LanguageServers {
 class FileDB final : public CodeComprehension::FileDB {
 public:
     FileDB() = default;
-    virtual Optional<DeprecatedString> get_or_read_from_filesystem(StringView filename) const override;
+    virtual Optional<ByteString> get_or_read_from_filesystem(StringView filename) const override;
 
-    RefPtr<const GUI::TextDocument> get_document(DeprecatedString const& filename) const;
-    RefPtr<GUI::TextDocument> get_document(DeprecatedString const& filename);
+    RefPtr<const GUI::TextDocument> get_document(ByteString const& filename) const;
+    RefPtr<GUI::TextDocument> get_document(ByteString const& filename);
 
-    bool add(DeprecatedString const& filename, int fd);
-    bool add(DeprecatedString const& filename, DeprecatedString const& content);
+    bool add(ByteString const& filename, int fd);
+    bool add(ByteString const& filename, ByteString const& content);
 
-    void on_file_edit_insert_text(DeprecatedString const& filename, DeprecatedString const& inserted_text, size_t start_line, size_t start_column);
-    void on_file_edit_remove_text(DeprecatedString const& filename, size_t start_line, size_t start_column, size_t end_line, size_t end_column);
-    DeprecatedString to_absolute_path(DeprecatedString const& filename) const;
-    bool is_open(DeprecatedString const& filename) const;
+    void on_file_edit_insert_text(ByteString const& filename, ByteString const& inserted_text, size_t start_line, size_t start_column);
+    void on_file_edit_remove_text(ByteString const& filename, size_t start_line, size_t start_column, size_t end_line, size_t end_column);
+    ByteString to_absolute_path(ByteString const& filename) const;
+    bool is_open(ByteString const& filename) const;
 
 private:
-    ErrorOr<NonnullRefPtr<GUI::TextDocument>> create_from_filesystem(DeprecatedString const& filename) const;
+    ErrorOr<NonnullRefPtr<GUI::TextDocument>> create_from_filesystem(ByteString const& filename) const;
     ErrorOr<NonnullRefPtr<GUI::TextDocument>> create_from_fd(int fd) const;
     ErrorOr<NonnullRefPtr<GUI::TextDocument>> create_from_file(NonnullOwnPtr<Core::File>) const;
-    static RefPtr<GUI::TextDocument> create_with_content(DeprecatedString const&);
+    static RefPtr<GUI::TextDocument> create_with_content(ByteString const&);
 
 private:
-    HashMap<DeprecatedString, NonnullRefPtr<GUI::TextDocument>> m_open_files;
-    Optional<DeprecatedString> m_project_root;
+    HashMap<ByteString, NonnullRefPtr<GUI::TextDocument>> m_open_files;
+    Optional<ByteString> m_project_root;
 };
 
 }
diff --git a/Userland/DevTools/HackStudio/LanguageServers/LanguageClient.ipc b/Userland/DevTools/HackStudio/LanguageServers/LanguageClient.ipc
index 68f724762fc..f20fd2e7ccf 100644
--- a/Userland/DevTools/HackStudio/LanguageServers/LanguageClient.ipc
+++ b/Userland/DevTools/HackStudio/LanguageServers/LanguageClient.ipc
@@ -2,8 +2,8 @@ endpoint LanguageClient
 {
     auto_complete_suggestions(Vector<CodeComprehension::AutocompleteResultEntry> suggestions) =|
     declaration_location(CodeComprehension::ProjectLocation location) =|
-    declarations_in_document(DeprecatedString filename, Vector<CodeComprehension::Declaration> declarations) =|
-    todo_entries_in_document(DeprecatedString filename, Vector<CodeComprehension::TodoEntry> todo_entries) =|
-    parameters_hint_result(Vector<DeprecatedString> params, int current_index) =|
+    declarations_in_document(ByteString filename, Vector<CodeComprehension::Declaration> declarations) =|
+    todo_entries_in_document(ByteString filename, Vector<CodeComprehension::TodoEntry> todo_entries) =|
+    parameters_hint_result(Vector<ByteString> params, int current_index) =|
     tokens_info_result(Vector<CodeComprehension::TokenInfo> tokens_info) =|
 }
diff --git a/Userland/DevTools/HackStudio/LanguageServers/LanguageServer.ipc b/Userland/DevTools/HackStudio/LanguageServers/LanguageServer.ipc
index 23dfe681b9e..5f4b7b45e42 100644
--- a/Userland/DevTools/HackStudio/LanguageServers/LanguageServer.ipc
+++ b/Userland/DevTools/HackStudio/LanguageServers/LanguageServer.ipc
@@ -1,15 +1,15 @@
 endpoint LanguageServer
 {
-    greet(DeprecatedString project_root) =|
+    greet(ByteString project_root) =|
 
-    file_opened(DeprecatedString filename, IPC::File file) =|
-    file_edit_insert_text(DeprecatedString filename, DeprecatedString text, i32 start_line, i32 start_column) =|
-    file_edit_remove_text(DeprecatedString filename, i32 start_line, i32 start_column, i32 end_line, i32 end_column) =|
-    set_file_content(DeprecatedString filename, DeprecatedString content) =|
+    file_opened(ByteString filename, IPC::File file) =|
+    file_edit_insert_text(ByteString filename, ByteString text, i32 start_line, i32 start_column) =|
+    file_edit_remove_text(ByteString filename, i32 start_line, i32 start_column, i32 end_line, i32 end_column) =|
+    set_file_content(ByteString filename, ByteString content) =|
 
     auto_complete_suggestions(CodeComprehension::ProjectLocation location) =|
     find_declaration(CodeComprehension::ProjectLocation location) =|
     get_parameters_hint(CodeComprehension::ProjectLocation location) =|
-    get_tokens_info(DeprecatedString filename) =|
+    get_tokens_info(ByteString filename) =|
 
 }
diff --git a/Userland/DevTools/HackStudio/LanguageServers/Shell/ConnectionFromClient.h b/Userland/DevTools/HackStudio/LanguageServers/Shell/ConnectionFromClient.h
index 44a0f1a30c4..aab13a056bf 100644
--- a/Userland/DevTools/HackStudio/LanguageServers/Shell/ConnectionFromClient.h
+++ b/Userland/DevTools/HackStudio/LanguageServers/Shell/ConnectionFromClient.h
@@ -20,10 +20,10 @@ private:
         : LanguageServers::ConnectionFromClient(move(socket))
     {
         m_autocomplete_engine = make<CodeComprehension::Shell::ShellComprehensionEngine>(m_filedb);
-        m_autocomplete_engine->set_declarations_of_document_callback = [this](DeprecatedString const& filename, Vector<CodeComprehension::Declaration>&& declarations) {
+        m_autocomplete_engine->set_declarations_of_document_callback = [this](ByteString const& filename, Vector<CodeComprehension::Declaration>&& declarations) {
             async_declarations_in_document(filename, move(declarations));
         };
-        m_autocomplete_engine->set_todo_entries_of_document_callback = [this](DeprecatedString const& filename, Vector<CodeComprehension::TodoEntry>&& todo_entries) {
+        m_autocomplete_engine->set_todo_entries_of_document_callback = [this](ByteString const& filename, Vector<CodeComprehension::TodoEntry>&& todo_entries) {
             async_todo_entries_in_document(filename, move(todo_entries));
         };
     }
diff --git a/Userland/DevTools/HackStudio/Locator.cpp b/Userland/DevTools/HackStudio/Locator.cpp
index 582bc2ff0a1..54b031949f9 100644
--- a/Userland/DevTools/HackStudio/Locator.cpp
+++ b/Userland/DevTools/HackStudio/Locator.cpp
@@ -21,13 +21,13 @@ namespace HackStudio {
 class LocatorSuggestionModel final : public GUI::Model {
 public:
     struct Suggestion {
-        static Suggestion create_filename(DeprecatedString const& filename);
+        static Suggestion create_filename(ByteString const& filename);
         static Suggestion create_symbol_declaration(CodeComprehension::Declaration const&);
 
         bool is_filename() const { return as_filename.has_value(); }
         bool is_symbol_declaration() const { return as_symbol_declaration.has_value(); }
 
-        Optional<DeprecatedString> as_filename;
+        Optional<ByteString> as_filename;
         Optional<CodeComprehension::Declaration> as_symbol_declaration;
     };
 
@@ -62,7 +62,7 @@ public:
             if (index.column() == Column::Name) {
                 if (!suggestion.as_symbol_declaration.value().scope.is_empty())
                     return suggestion.as_symbol_declaration.value().name;
-                return DeprecatedString::formatted("{}::{}", suggestion.as_symbol_declaration.value().scope, suggestion.as_symbol_declaration.value().name);
+                return ByteString::formatted("{}::{}", suggestion.as_symbol_declaration.value().scope, suggestion.as_symbol_declaration.value().name);
             }
             if (index.column() == Column::Filename)
                 return suggestion.as_symbol_declaration.value().position.file;
@@ -82,7 +82,7 @@ private:
     Vector<Suggestion> m_suggestions;
 };
 
-LocatorSuggestionModel::Suggestion LocatorSuggestionModel::Suggestion::create_filename(DeprecatedString const& filename)
+LocatorSuggestionModel::Suggestion LocatorSuggestionModel::Suggestion::create_filename(ByteString const& filename)
 {
     LocatorSuggestionModel::Suggestion s;
     s.as_filename = filename;
diff --git a/Userland/DevTools/HackStudio/Project.cpp b/Userland/DevTools/HackStudio/Project.cpp
index 1358958cc2a..3bde5faa804 100644
--- a/Userland/DevTools/HackStudio/Project.cpp
+++ b/Userland/DevTools/HackStudio/Project.cpp
@@ -10,13 +10,13 @@
 
 namespace HackStudio {
 
-Project::Project(DeprecatedString const& root_path)
+Project::Project(ByteString const& root_path)
     : m_root_path(root_path)
 {
     m_model = GUI::FileSystemModel::create(root_path, GUI::FileSystemModel::Mode::FilesAndDirectories);
 }
 
-OwnPtr<Project> Project::open_with_root_path(DeprecatedString const& root_path)
+OwnPtr<Project> Project::open_with_root_path(ByteString const& root_path)
 {
     if (!FileSystem::is_directory(root_path))
         return {};
@@ -45,18 +45,18 @@ void Project::for_each_text_file(Function<void(ProjectFile const&)> callback) co
     });
 }
 
-NonnullRefPtr<ProjectFile> Project::create_file(DeprecatedString const& path) const
+NonnullRefPtr<ProjectFile> Project::create_file(ByteString const& path) const
 {
     auto full_path = to_absolute_path(path);
     return ProjectFile::construct_with_name(full_path);
 }
 
-DeprecatedString Project::to_absolute_path(DeprecatedString const& path) const
+ByteString Project::to_absolute_path(ByteString const& path) const
 {
     if (LexicalPath { path }.is_absolute()) {
         return path;
     }
-    return LexicalPath { DeprecatedString::formatted("{}/{}", m_root_path, path) }.string();
+    return LexicalPath { ByteString::formatted("{}/{}", m_root_path, path) }.string();
 }
 
 bool Project::project_is_serenity() const
diff --git a/Userland/DevTools/HackStudio/Project.h b/Userland/DevTools/HackStudio/Project.h
index 62522a8626c..f0698b91143 100644
--- a/Userland/DevTools/HackStudio/Project.h
+++ b/Userland/DevTools/HackStudio/Project.h
@@ -20,28 +20,28 @@ class Project {
     AK_MAKE_NONMOVABLE(Project);
 
 public:
-    static OwnPtr<Project> open_with_root_path(DeprecatedString const& root_path);
+    static OwnPtr<Project> open_with_root_path(ByteString const& root_path);
 
     GUI::FileSystemModel& model() { return *m_model; }
     const GUI::FileSystemModel& model() const { return *m_model; }
-    DeprecatedString name() const { return LexicalPath::basename(m_root_path); }
-    DeprecatedString root_path() const { return m_root_path; }
+    ByteString name() const { return LexicalPath::basename(m_root_path); }
+    ByteString root_path() const { return m_root_path; }
 
-    NonnullRefPtr<ProjectFile> create_file(DeprecatedString const& path) const;
+    NonnullRefPtr<ProjectFile> create_file(ByteString const& path) const;
 
     void for_each_text_file(Function<void(ProjectFile const&)>) const;
-    DeprecatedString to_absolute_path(DeprecatedString const&) const;
+    ByteString to_absolute_path(ByteString const&) const;
     bool project_is_serenity() const;
 
     static constexpr auto config_file_path = ".hackstudio/config.json"sv;
     NonnullOwnPtr<ProjectConfig> config() const;
 
 private:
-    explicit Project(DeprecatedString const& root_path);
+    explicit Project(ByteString const& root_path);
 
     RefPtr<GUI::FileSystemModel> m_model;
 
-    DeprecatedString m_root_path;
+    ByteString m_root_path;
 };
 
 }
diff --git a/Userland/DevTools/HackStudio/ProjectBuilder.cpp b/Userland/DevTools/HackStudio/ProjectBuilder.cpp
index ae8e3e019c3..cf39e50f153 100644
--- a/Userland/DevTools/HackStudio/ProjectBuilder.cpp
+++ b/Userland/DevTools/HackStudio/ProjectBuilder.cpp
@@ -35,7 +35,7 @@ ErrorOr<void> ProjectBuilder::build(StringView active_file)
         return Error::from_string_literal("no active file");
 
     if (active_file.ends_with(".js"sv)) {
-        TRY(m_terminal->run_command(DeprecatedString::formatted("js -A {}", active_file)));
+        TRY(m_terminal->run_command(ByteString::formatted("js -A {}", active_file)));
         return {};
     }
 
@@ -61,7 +61,7 @@ ErrorOr<void> ProjectBuilder::run(StringView active_file)
         return Error::from_string_literal("no active file");
 
     if (active_file.ends_with(".js"sv)) {
-        TRY(m_terminal->run_command(DeprecatedString::formatted("js {}", active_file)));
+        TRY(m_terminal->run_command(ByteString::formatted("js {}", active_file)));
         return {};
     }
 
@@ -105,11 +105,11 @@ ErrorOr<void> ProjectBuilder::update_active_file(StringView active_file)
 ErrorOr<void> ProjectBuilder::build_serenity_component()
 {
     TRY(verify_make_is_installed());
-    TRY(m_terminal->run_command(DeprecatedString::formatted("make {}", m_serenity_component_name), build_directory(), TerminalWrapper::WaitForExit::Yes, "Make failed"sv));
+    TRY(m_terminal->run_command(ByteString::formatted("make {}", m_serenity_component_name), build_directory(), TerminalWrapper::WaitForExit::Yes, "Make failed"sv));
     return {};
 }
 
-ErrorOr<DeprecatedString> ProjectBuilder::component_name(StringView cmake_file_path)
+ErrorOr<ByteString> ProjectBuilder::component_name(StringView cmake_file_path)
 {
     auto file = TRY(Core::File::open(cmake_file_path, Core::File::OpenMode::Read));
     auto content = TRY(file->read_until_eof());
@@ -119,7 +119,7 @@ ErrorOr<DeprecatedString> ProjectBuilder::component_name(StringView cmake_file_p
     if (!component_name.search(StringView { content }, result))
         return Error::from_string_literal("component not found");
 
-    return DeprecatedString { result.capture_group_matches.at(0).at(0).view.string_view() };
+    return ByteString { result.capture_group_matches.at(0).at(0).view.string_view() };
 }
 
 ErrorOr<void> ProjectBuilder::initialize_build_directory()
@@ -137,15 +137,15 @@ ErrorOr<void> ProjectBuilder::initialize_build_directory()
     auto cmake_file = TRY(Core::File::open(cmake_file_path, Core::File::OpenMode::Write));
     TRY(cmake_file->write_until_depleted(generate_cmake_file_content().bytes()));
 
-    TRY(m_terminal->run_command(DeprecatedString::formatted("cmake -S {} -DHACKSTUDIO_BUILD=ON -DHACKSTUDIO_BUILD_CMAKE_FILE={}"
-                                                            " -DENABLE_UNICODE_DATABASE_DOWNLOAD=OFF",
+    TRY(m_terminal->run_command(ByteString::formatted("cmake -S {} -DHACKSTUDIO_BUILD=ON -DHACKSTUDIO_BUILD_CMAKE_FILE={}"
+                                                      " -DENABLE_UNICODE_DATABASE_DOWNLOAD=OFF",
                                     m_project_root, cmake_file_path),
         build_directory(), TerminalWrapper::WaitForExit::Yes, "CMake error"sv));
 
     return {};
 }
 
-Optional<DeprecatedString> ProjectBuilder::find_cmake_file_for(StringView file_path) const
+Optional<ByteString> ProjectBuilder::find_cmake_file_for(StringView file_path) const
 {
     auto directory = LexicalPath::dirname(file_path);
     while (!directory.is_empty()) {
@@ -157,7 +157,7 @@ Optional<DeprecatedString> ProjectBuilder::find_cmake_file_for(StringView file_p
     return {};
 }
 
-DeprecatedString ProjectBuilder::generate_cmake_file_content() const
+ByteString ProjectBuilder::generate_cmake_file_content() const
 {
     StringBuilder builder;
     builder.appendff("add_subdirectory({})\n", LexicalPath::dirname(m_serenity_component_cmake_file));
@@ -174,20 +174,20 @@ DeprecatedString ProjectBuilder::generate_cmake_file_content() const
         // all of their direct dependencies in the CMakeLists file.
         // For example, a target may directly use LibGFX but only specify LibGUI as a dependency (which in turn depends on LibGFX).
         // In this example, if we don't specify the dependencies of LibGUI in the CMake file, linking will fail because of undefined LibGFX symbols.
-        builder.appendff("target_link_libraries({} INTERFACE {})\n", library.key, DeprecatedString::join(' ', library.value->dependencies));
+        builder.appendff("target_link_libraries({} INTERFACE {})\n", library.key, ByteString::join(' ', library.value->dependencies));
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-HashMap<DeprecatedString, NonnullOwnPtr<ProjectBuilder::LibraryInfo>> ProjectBuilder::get_defined_libraries()
+HashMap<ByteString, NonnullOwnPtr<ProjectBuilder::LibraryInfo>> ProjectBuilder::get_defined_libraries()
 {
-    HashMap<DeprecatedString, NonnullOwnPtr<ProjectBuilder::LibraryInfo>> libraries;
+    HashMap<ByteString, NonnullOwnPtr<ProjectBuilder::LibraryInfo>> libraries;
 
-    for_each_library_definition([&libraries](DeprecatedString name, DeprecatedString path) {
+    for_each_library_definition([&libraries](ByteString name, ByteString path) {
         libraries.set(name, make<ProjectBuilder::LibraryInfo>(move(path)));
     });
-    for_each_library_dependencies([&libraries](DeprecatedString name, Vector<StringView> const& dependencies) {
+    for_each_library_dependencies([&libraries](ByteString name, Vector<StringView> const& dependencies) {
         auto library = libraries.get(name);
         if (!library.has_value())
             return;
@@ -199,9 +199,9 @@ HashMap<DeprecatedString, NonnullOwnPtr<ProjectBuilder::LibraryInfo>> ProjectBui
     return libraries;
 }
 
-void ProjectBuilder::for_each_library_definition(Function<void(DeprecatedString, DeprecatedString)> func)
+void ProjectBuilder::for_each_library_definition(Function<void(ByteString, ByteString)> func)
 {
-    Vector<DeprecatedString> arguments = { "-c", "find Userland -name CMakeLists.txt | xargs grep serenity_lib" };
+    Vector<ByteString> arguments = { "-c", "find Userland -name CMakeLists.txt | xargs grep serenity_lib" };
     auto res = Core::command("/bin/sh", arguments, {});
     if (res.is_error()) {
         warnln("{}", res.error());
@@ -218,7 +218,7 @@ void ProjectBuilder::for_each_library_definition(Function<void(DeprecatedString,
 
         auto library_name = result.capture_group_matches.at(0).at(0).view.string_view();
         auto library_obj_name = result.capture_group_matches.at(0).at(1).view.string_view();
-        auto so_path = DeprecatedString::formatted("{}.so", LexicalPath::join("/usr/lib"sv, DeprecatedString::formatted("lib{}", library_obj_name)).string());
+        auto so_path = ByteString::formatted("{}.so", LexicalPath::join("/usr/lib"sv, ByteString::formatted("lib{}", library_obj_name)).string());
         func(library_name, so_path);
     }
 
@@ -226,9 +226,9 @@ void ProjectBuilder::for_each_library_definition(Function<void(DeprecatedString,
     func("ssp", "/usr/lib/libssp.a");
 }
 
-void ProjectBuilder::for_each_library_dependencies(Function<void(DeprecatedString, Vector<StringView>)> func)
+void ProjectBuilder::for_each_library_dependencies(Function<void(ByteString, Vector<StringView>)> func)
 {
-    Vector<DeprecatedString> arguments = { "-c", "find Userland/Libraries -name CMakeLists.txt | xargs grep target_link_libraries" };
+    Vector<ByteString> arguments = { "-c", "find Userland/Libraries -name CMakeLists.txt | xargs grep target_link_libraries" };
     auto res = Core::command("/bin/sh", arguments, {});
     if (res.is_error()) {
         warnln("{}", res.error());
@@ -267,7 +267,7 @@ ErrorOr<void> ProjectBuilder::verify_make_is_installed()
     return Error::from_string_literal("Make port is not installed");
 }
 
-DeprecatedString ProjectBuilder::build_directory() const
+ByteString ProjectBuilder::build_directory() const
 {
     return LexicalPath::join(m_project_root, "Build"sv).string();
 }
diff --git a/Userland/DevTools/HackStudio/ProjectBuilder.h b/Userland/DevTools/HackStudio/ProjectBuilder.h
index c579202e1b7..194f38d5d7a 100644
--- a/Userland/DevTools/HackStudio/ProjectBuilder.h
+++ b/Userland/DevTools/HackStudio/ProjectBuilder.h
@@ -32,27 +32,27 @@ private:
     ErrorOr<void> build_serenity_component();
     ErrorOr<void> run_serenity_component();
     ErrorOr<void> initialize_build_directory();
-    Optional<DeprecatedString> find_cmake_file_for(StringView file_path) const;
-    DeprecatedString generate_cmake_file_content() const;
+    Optional<ByteString> find_cmake_file_for(StringView file_path) const;
+    ByteString generate_cmake_file_content() const;
     ErrorOr<void> update_active_file(StringView active_file);
-    DeprecatedString build_directory() const;
+    ByteString build_directory() const;
 
     struct LibraryInfo {
-        DeprecatedString path;
-        Vector<DeprecatedString> dependencies {};
+        ByteString path;
+        Vector<ByteString> dependencies {};
     };
-    static HashMap<DeprecatedString, NonnullOwnPtr<LibraryInfo>> get_defined_libraries();
-    static void for_each_library_definition(Function<void(DeprecatedString, DeprecatedString)>);
-    static void for_each_library_dependencies(Function<void(DeprecatedString, Vector<StringView>)>);
-    static ErrorOr<DeprecatedString> component_name(StringView cmake_file_path);
+    static HashMap<ByteString, NonnullOwnPtr<LibraryInfo>> get_defined_libraries();
+    static void for_each_library_definition(Function<void(ByteString, ByteString)>);
+    static void for_each_library_dependencies(Function<void(ByteString, Vector<StringView>)>);
+    static ErrorOr<ByteString> component_name(StringView cmake_file_path);
     static ErrorOr<void> verify_cmake_is_installed();
     static ErrorOr<void> verify_make_is_installed();
 
-    DeprecatedString m_project_root;
+    ByteString m_project_root;
     Project const& m_project;
     NonnullRefPtr<TerminalWrapper> m_terminal;
     IsSerenityRepo m_is_serenity { IsSerenityRepo::No };
-    DeprecatedString m_serenity_component_cmake_file;
-    DeprecatedString m_serenity_component_name;
+    ByteString m_serenity_component_cmake_file;
+    ByteString m_serenity_component_name;
 };
 }
diff --git a/Userland/DevTools/HackStudio/ProjectConfig.cpp b/Userland/DevTools/HackStudio/ProjectConfig.cpp
index 9687e36daff..746b5c4938d 100644
--- a/Userland/DevTools/HackStudio/ProjectConfig.cpp
+++ b/Userland/DevTools/HackStudio/ProjectConfig.cpp
@@ -15,7 +15,7 @@ ProjectConfig::ProjectConfig(JsonObject config)
 {
 }
 
-ErrorOr<NonnullOwnPtr<ProjectConfig>> ProjectConfig::try_load_project_config(DeprecatedString path)
+ErrorOr<NonnullOwnPtr<ProjectConfig>> ProjectConfig::try_load_project_config(ByteString path)
 {
     auto file = TRY(Core::File::open(path, Core::File::OpenMode::Read));
     auto file_contents = TRY(file->read_until_eof());
@@ -33,9 +33,9 @@ NonnullOwnPtr<ProjectConfig> ProjectConfig::create_empty()
     return adopt_own(*new ProjectConfig(empty));
 }
 
-Optional<DeprecatedString> ProjectConfig::read_key(DeprecatedString key_name) const
+Optional<ByteString> ProjectConfig::read_key(ByteString key_name) const
 {
-    return m_config.get_deprecated_string(key_name);
+    return m_config.get_byte_string(key_name);
 }
 
 }
diff --git a/Userland/DevTools/HackStudio/ProjectConfig.h b/Userland/DevTools/HackStudio/ProjectConfig.h
index 20019aa6a98..30ee7d2ffcd 100644
--- a/Userland/DevTools/HackStudio/ProjectConfig.h
+++ b/Userland/DevTools/HackStudio/ProjectConfig.h
@@ -16,16 +16,16 @@ namespace HackStudio {
 
 class ProjectConfig {
 public:
-    static ErrorOr<NonnullOwnPtr<ProjectConfig>> try_load_project_config(DeprecatedString path);
+    static ErrorOr<NonnullOwnPtr<ProjectConfig>> try_load_project_config(ByteString path);
     static NonnullOwnPtr<ProjectConfig> create_empty();
 
     ProjectConfig(JsonObject);
 
-    Optional<DeprecatedString> build_command() const { return read_key("build_command"); }
-    Optional<DeprecatedString> run_command() const { return read_key("run_command"); }
+    Optional<ByteString> build_command() const { return read_key("build_command"); }
+    Optional<ByteString> run_command() const { return read_key("run_command"); }
 
 private:
-    Optional<DeprecatedString> read_key(DeprecatedString key_name) const;
+    Optional<ByteString> read_key(ByteString key_name) const;
 
     JsonObject m_config;
 };
diff --git a/Userland/DevTools/HackStudio/ProjectDeclarations.cpp b/Userland/DevTools/HackStudio/ProjectDeclarations.cpp
index dff6118a079..b4adce4f7b0 100644
--- a/Userland/DevTools/HackStudio/ProjectDeclarations.cpp
+++ b/Userland/DevTools/HackStudio/ProjectDeclarations.cpp
@@ -11,7 +11,7 @@ HackStudio::ProjectDeclarations& HackStudio::ProjectDeclarations::the()
     static ProjectDeclarations s_instance;
     return s_instance;
 }
-void HackStudio::ProjectDeclarations::set_declared_symbols(DeprecatedString const& filename, Vector<CodeComprehension::Declaration> const& declarations)
+void HackStudio::ProjectDeclarations::set_declared_symbols(ByteString const& filename, Vector<CodeComprehension::Declaration> const& declarations)
 {
     m_document_to_declarations.set(filename, declarations);
     if (on_update)
diff --git a/Userland/DevTools/HackStudio/ProjectDeclarations.h b/Userland/DevTools/HackStudio/ProjectDeclarations.h
index ee1e6f53de9..d356cfd33ef 100644
--- a/Userland/DevTools/HackStudio/ProjectDeclarations.h
+++ b/Userland/DevTools/HackStudio/ProjectDeclarations.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/Noncopyable.h>
@@ -23,7 +23,7 @@ public:
     template<typename Func>
     void for_each_declared_symbol(Func);
 
-    void set_declared_symbols(DeprecatedString const& filename, Vector<CodeComprehension::Declaration> const&);
+    void set_declared_symbols(ByteString const& filename, Vector<CodeComprehension::Declaration> const&);
 
     static Optional<GUI::Icon> get_icon_for(CodeComprehension::DeclarationType);
 
@@ -31,7 +31,7 @@ public:
 
 private:
     ProjectDeclarations() = default;
-    HashMap<DeprecatedString, Vector<CodeComprehension::Declaration>> m_document_to_declarations;
+    HashMap<ByteString, Vector<CodeComprehension::Declaration>> m_document_to_declarations;
 };
 
 template<typename Func>
diff --git a/Userland/DevTools/HackStudio/ProjectFile.cpp b/Userland/DevTools/HackStudio/ProjectFile.cpp
index 35fba436b09..98ab665c475 100644
--- a/Userland/DevTools/HackStudio/ProjectFile.cpp
+++ b/Userland/DevTools/HackStudio/ProjectFile.cpp
@@ -9,7 +9,7 @@
 
 namespace HackStudio {
 
-ProjectFile::ProjectFile(DeprecatedString const& name)
+ProjectFile::ProjectFile(ByteString const& name)
     : m_name(name)
 {
 }
diff --git a/Userland/DevTools/HackStudio/ProjectFile.h b/Userland/DevTools/HackStudio/ProjectFile.h
index b4e38eca73d..d8fd6e10a0b 100644
--- a/Userland/DevTools/HackStudio/ProjectFile.h
+++ b/Userland/DevTools/HackStudio/ProjectFile.h
@@ -8,7 +8,7 @@
 
 #include "CodeDocument.h"
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefCounted.h>
 
@@ -16,12 +16,12 @@ namespace HackStudio {
 
 class ProjectFile : public RefCounted<ProjectFile> {
 public:
-    static NonnullRefPtr<ProjectFile> construct_with_name(DeprecatedString const& name)
+    static NonnullRefPtr<ProjectFile> construct_with_name(ByteString const& name)
     {
         return adopt_ref(*new ProjectFile(name));
     }
 
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
     bool could_render_text() const { return m_could_render_text; }
 
     GUI::TextDocument& document() const;
@@ -33,10 +33,10 @@ public:
     void horizontal_scroll_value(int);
 
 private:
-    explicit ProjectFile(DeprecatedString const& name);
+    explicit ProjectFile(ByteString const& name);
     void create_document_if_needed() const;
 
-    DeprecatedString m_name;
+    ByteString m_name;
     mutable RefPtr<CodeDocument> m_document;
     mutable bool m_could_render_text { false };
     int m_vertical_scroll_value { 0 };
diff --git a/Userland/DevTools/HackStudio/ProjectTemplate.cpp b/Userland/DevTools/HackStudio/ProjectTemplate.cpp
index 9ba02a85f43..415329b8b30 100644
--- a/Userland/DevTools/HackStudio/ProjectTemplate.cpp
+++ b/Userland/DevTools/HackStudio/ProjectTemplate.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "ProjectTemplate.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/ConfigFile.h>
@@ -19,7 +19,7 @@
 
 namespace HackStudio {
 
-ProjectTemplate::ProjectTemplate(DeprecatedString const& id, DeprecatedString const& name, DeprecatedString const& description, const GUI::Icon& icon, int priority)
+ProjectTemplate::ProjectTemplate(ByteString const& id, ByteString const& name, ByteString const& description, const GUI::Icon& icon, int priority)
     : m_id(id)
     , m_name(name)
     , m_description(description)
@@ -28,7 +28,7 @@ ProjectTemplate::ProjectTemplate(DeprecatedString const& id, DeprecatedString co
 {
 }
 
-RefPtr<ProjectTemplate> ProjectTemplate::load_from_manifest(DeprecatedString const& manifest_path)
+RefPtr<ProjectTemplate> ProjectTemplate::load_from_manifest(ByteString const& manifest_path)
 {
     auto maybe_config = Core::ConfigFile::open(manifest_path);
     if (maybe_config.is_error())
@@ -50,7 +50,7 @@ RefPtr<ProjectTemplate> ProjectTemplate::load_from_manifest(DeprecatedString con
     // Fallback to a generic executable icon if one isn't found
     auto icon = GUI::Icon::default_icon("filetype-executable"sv);
 
-    auto bitmap_path_32 = DeprecatedString::formatted("/res/icons/hackstudio/templates-32x32/{}.png", config->read_entry("HackStudioTemplate", "IconName32x"));
+    auto bitmap_path_32 = ByteString::formatted("/res/icons/hackstudio/templates-32x32/{}.png", config->read_entry("HackStudioTemplate", "IconName32x"));
 
     if (FileSystem::exists(bitmap_path_32)) {
         auto bitmap_or_error = Gfx::Bitmap::load_from_file(bitmap_path_32);
@@ -61,11 +61,11 @@ RefPtr<ProjectTemplate> ProjectTemplate::load_from_manifest(DeprecatedString con
     return adopt_ref(*new ProjectTemplate(id, name, description, icon, priority));
 }
 
-Result<void, DeprecatedString> ProjectTemplate::create_project(DeprecatedString const& name, DeprecatedString const& path)
+Result<void, ByteString> ProjectTemplate::create_project(ByteString const& name, ByteString const& path)
 {
     // Check if a file or directory already exists at the project path
     if (FileSystem::exists(path))
-        return DeprecatedString("File or directory already exists at specified location.");
+        return ByteString("File or directory already exists at specified location.");
 
     dbgln("Creating project at path '{}' with name '{}'", path, name);
 
@@ -75,19 +75,19 @@ Result<void, DeprecatedString> ProjectTemplate::create_project(DeprecatedString
         auto result = FileSystem::copy_file_or_directory(path, content_path());
         dbgln("Copying {} -> {}", content_path(), path);
         if (result.is_error())
-            return DeprecatedString::formatted("Failed to copy template contents. Error code: {}", static_cast<Error const&>(result.error()));
+            return ByteString::formatted("Failed to copy template contents. Error code: {}", static_cast<Error const&>(result.error()));
     } else {
         dbgln("No template content directory found for '{}', creating an empty directory for the project.", m_id);
         int rc;
         if ((rc = mkdir(path.characters(), 0755)) < 0) {
-            return DeprecatedString::formatted("Failed to mkdir empty project directory, error: {}, rc: {}.", strerror(errno), rc);
+            return ByteString::formatted("Failed to mkdir empty project directory, error: {}, rc: {}.", strerror(errno), rc);
         }
     }
 
     // Check for an executable post-create script in $TEMPLATES_DIR/$ID.postcreate,
     // and run it with the path and name
 
-    auto postcreate_script_path = LexicalPath::canonicalized_path(DeprecatedString::formatted("{}/{}.postcreate", templates_path(), m_id));
+    auto postcreate_script_path = LexicalPath::canonicalized_path(ByteString::formatted("{}/{}.postcreate", templates_path(), m_id));
     struct stat postcreate_st;
     int result = stat(postcreate_script_path.characters(), &postcreate_st);
     if (result == 0 && (postcreate_st.st_mode & S_IXOTH) == S_IXOTH) {
@@ -101,19 +101,19 @@ Result<void, DeprecatedString> ProjectTemplate::create_project(DeprecatedString
 
         if ((errno = posix_spawn(&child_pid, postcreate_script_path.characters(), nullptr, nullptr, const_cast<char**>(argv), environ))) {
             perror("posix_spawn");
-            return DeprecatedString("Failed to spawn project post-create script.");
+            return ByteString("Failed to spawn project post-create script.");
         }
 
         // Command spawned, wait for exit.
         int status;
         if (waitpid(child_pid, &status, 0) < 0)
-            return DeprecatedString("Failed to spawn project post-create script.");
+            return ByteString("Failed to spawn project post-create script.");
 
         int child_error = WEXITSTATUS(status);
         dbgln("Post-create script exited with code {}", child_error);
 
         if (child_error != 0)
-            return DeprecatedString("Project post-creation script exited with non-zero error code.");
+            return ByteString("Project post-creation script exited with non-zero error code.");
     }
 
     return {};
diff --git a/Userland/DevTools/HackStudio/ProjectTemplate.h b/Userland/DevTools/HackStudio/ProjectTemplate.h
index 3d3bb85322c..e8075421b29 100644
--- a/Userland/DevTools/HackStudio/ProjectTemplate.h
+++ b/Userland/DevTools/HackStudio/ProjectTemplate.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/RefCounted.h>
 #include <AK/Result.h>
@@ -18,28 +18,28 @@ namespace HackStudio {
 
 class ProjectTemplate : public RefCounted<ProjectTemplate> {
 public:
-    static DeprecatedString templates_path() { return "/res/devel/templates"; }
+    static ByteString templates_path() { return "/res/devel/templates"; }
 
-    static RefPtr<ProjectTemplate> load_from_manifest(DeprecatedString const& manifest_path);
+    static RefPtr<ProjectTemplate> load_from_manifest(ByteString const& manifest_path);
 
-    explicit ProjectTemplate(DeprecatedString const& id, DeprecatedString const& name, DeprecatedString const& description, const GUI::Icon& icon, int priority);
+    explicit ProjectTemplate(ByteString const& id, ByteString const& name, ByteString const& description, const GUI::Icon& icon, int priority);
 
-    Result<void, DeprecatedString> create_project(DeprecatedString const& name, DeprecatedString const& path);
+    Result<void, ByteString> create_project(ByteString const& name, ByteString const& path);
 
-    DeprecatedString const& id() const { return m_id; }
-    DeprecatedString const& name() const { return m_name; }
-    DeprecatedString const& description() const { return m_description; }
+    ByteString const& id() const { return m_id; }
+    ByteString const& name() const { return m_name; }
+    ByteString const& description() const { return m_description; }
     const GUI::Icon& icon() const { return m_icon; }
-    const DeprecatedString content_path() const
+    const ByteString content_path() const
     {
-        return LexicalPath::canonicalized_path(DeprecatedString::formatted("{}/{}", templates_path(), m_id));
+        return LexicalPath::canonicalized_path(ByteString::formatted("{}/{}", templates_path(), m_id));
     }
     int priority() const { return m_priority; }
 
 private:
-    DeprecatedString m_id;
-    DeprecatedString m_name;
-    DeprecatedString m_description;
+    ByteString m_id;
+    ByteString m_name;
+    ByteString m_description;
     GUI::Icon m_icon;
     int m_priority { 0 };
 };
diff --git a/Userland/DevTools/HackStudio/TerminalWrapper.cpp b/Userland/DevTools/HackStudio/TerminalWrapper.cpp
index a7bb513fcb2..a62db7d440f 100644
--- a/Userland/DevTools/HackStudio/TerminalWrapper.cpp
+++ b/Userland/DevTools/HackStudio/TerminalWrapper.cpp
@@ -6,7 +6,7 @@
  */
 
 #include "TerminalWrapper.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/System.h>
 #include <LibGUI/Application.h>
 #include <LibGUI/BoxLayout.h>
@@ -24,7 +24,7 @@
 
 namespace HackStudio {
 
-ErrorOr<void> TerminalWrapper::run_command(DeprecatedString const& command, Optional<DeprecatedString> working_directory, WaitForExit wait_for_exit, Optional<StringView> failure_message)
+ErrorOr<void> TerminalWrapper::run_command(ByteString const& command, Optional<ByteString> working_directory, WaitForExit wait_for_exit, Optional<StringView> failure_message)
 {
     if (m_pid != -1) {
         GUI::MessageBox::show(window(),
@@ -92,11 +92,11 @@ ErrorOr<int> TerminalWrapper::setup_master_pseudoterminal(WaitForChildOnExit wai
             int wstatus = result.release_value().status;
 
             if (WIFEXITED(wstatus)) {
-                m_terminal_widget->inject_string(DeprecatedString::formatted("\033[{};1m(Command exited with code {})\033[0m\r\n", wstatus == 0 ? 32 : 31, WEXITSTATUS(wstatus)));
+                m_terminal_widget->inject_string(ByteString::formatted("\033[{};1m(Command exited with code {})\033[0m\r\n", wstatus == 0 ? 32 : 31, WEXITSTATUS(wstatus)));
             } else if (WIFSTOPPED(wstatus)) {
                 m_terminal_widget->inject_string("\033[34;1m(Command stopped!)\033[0m\r\n"sv);
             } else if (WIFSIGNALED(wstatus)) {
-                m_terminal_widget->inject_string(DeprecatedString::formatted("\033[34;1m(Command signaled with {}!)\033[0m\r\n", strsignal(WTERMSIG(wstatus))));
+                m_terminal_widget->inject_string(ByteString::formatted("\033[34;1m(Command signaled with {}!)\033[0m\r\n", strsignal(WTERMSIG(wstatus))));
             }
 
             m_child_exit_status = WEXITSTATUS(wstatus);
diff --git a/Userland/DevTools/HackStudio/TerminalWrapper.h b/Userland/DevTools/HackStudio/TerminalWrapper.h
index e4e94031f1d..5355a8504ba 100644
--- a/Userland/DevTools/HackStudio/TerminalWrapper.h
+++ b/Userland/DevTools/HackStudio/TerminalWrapper.h
@@ -21,7 +21,7 @@ public:
         No,
         Yes
     };
-    ErrorOr<void> run_command(DeprecatedString const&, Optional<DeprecatedString> working_directory = {}, WaitForExit = WaitForExit::No, Optional<StringView> failure_message = {});
+    ErrorOr<void> run_command(ByteString const&, Optional<ByteString> working_directory = {}, WaitForExit = WaitForExit::No, Optional<StringView> failure_message = {});
     ErrorOr<void> kill_running_command();
     void clear_including_history();
 
diff --git a/Userland/DevTools/HackStudio/ToDoEntries.cpp b/Userland/DevTools/HackStudio/ToDoEntries.cpp
index 9c81dce40d3..5860946a7f9 100644
--- a/Userland/DevTools/HackStudio/ToDoEntries.cpp
+++ b/Userland/DevTools/HackStudio/ToDoEntries.cpp
@@ -14,7 +14,7 @@ ToDoEntries& HackStudio::ToDoEntries::the()
     return s_instance;
 }
 
-void ToDoEntries::set_entries(DeprecatedString const& filename, Vector<CodeComprehension::TodoEntry> const&& entries)
+void ToDoEntries::set_entries(ByteString const& filename, Vector<CodeComprehension::TodoEntry> const&& entries)
 {
     m_document_to_entries.set(filename, move(entries));
     if (on_update)
diff --git a/Userland/DevTools/HackStudio/ToDoEntries.h b/Userland/DevTools/HackStudio/ToDoEntries.h
index d693e1945e3..31e3358dba1 100644
--- a/Userland/DevTools/HackStudio/ToDoEntries.h
+++ b/Userland/DevTools/HackStudio/ToDoEntries.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/Noncopyable.h>
@@ -20,7 +20,7 @@ class ToDoEntries {
 public:
     static ToDoEntries& the();
 
-    void set_entries(DeprecatedString const& filename, Vector<CodeComprehension::TodoEntry> const&& entries);
+    void set_entries(ByteString const& filename, Vector<CodeComprehension::TodoEntry> const&& entries);
 
     Vector<CodeComprehension::TodoEntry> get_entries();
 
@@ -30,7 +30,7 @@ public:
 
 private:
     ToDoEntries() = default;
-    HashMap<DeprecatedString, Vector<CodeComprehension::TodoEntry>> m_document_to_entries;
+    HashMap<ByteString, Vector<CodeComprehension::TodoEntry>> m_document_to_entries;
 };
 
 }
diff --git a/Userland/DevTools/HackStudio/ToDoEntriesWidget.cpp b/Userland/DevTools/HackStudio/ToDoEntriesWidget.cpp
index 5c87472ac85..d3b73557ec3 100644
--- a/Userland/DevTools/HackStudio/ToDoEntriesWidget.cpp
+++ b/Userland/DevTools/HackStudio/ToDoEntriesWidget.cpp
@@ -63,9 +63,9 @@ public:
             case Column::Text:
                 return match.content;
             case Column::Line:
-                return DeprecatedString::formatted("{}", match.line + 1);
+                return ByteString::formatted("{}", match.line + 1);
             case Column::Column:
-                return DeprecatedString::formatted("{}", match.column);
+                return ByteString::formatted("{}", match.column);
             }
         }
         return {};
diff --git a/Userland/DevTools/HackStudio/main.cpp b/Userland/DevTools/HackStudio/main.cpp
index 1ecf881e5a3..7d5eb7e0775 100644
--- a/Userland/DevTools/HackStudio/main.cpp
+++ b/Userland/DevTools/HackStudio/main.cpp
@@ -33,7 +33,7 @@ static WeakPtr<HackStudioWidget> s_hack_studio_widget;
 static bool make_is_available();
 static ErrorOr<void> notify_make_not_available();
 static void update_path_environment_variable();
-static Optional<DeprecatedString> last_opened_project_path();
+static Optional<ByteString> last_opened_project_path();
 static ErrorOr<NonnullRefPtr<HackStudioWidget>> create_hack_studio_widget(bool mode_coredump, StringView path, pid_t pid_to_debug);
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
@@ -68,7 +68,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     window->set_main_widget(hack_studio_widget);
     s_hack_studio_widget = hack_studio_widget;
 
-    window->set_title(DeprecatedString::formatted("{} - Hack Studio", hack_studio_widget->project().name()));
+    window->set_title(ByteString::formatted("{} - Hack Studio", hack_studio_widget->project().name()));
 
     TRY(hack_studio_widget->initialize_menubar(*window));
 
@@ -131,10 +131,10 @@ static void update_path_environment_variable()
     if (path.length())
         path.append(':');
     path.append(DEFAULT_PATH_SV);
-    setenv("PATH", path.to_deprecated_string().characters(), true);
+    setenv("PATH", path.to_byte_string().characters(), true);
 }
 
-static Optional<DeprecatedString> last_opened_project_path()
+static Optional<ByteString> last_opened_project_path()
 {
     auto projects = HackStudioWidget::read_recent_projects();
     if (projects.size() == 0)
@@ -153,12 +153,12 @@ GUI::TextEditor& current_editor()
     return s_hack_studio_widget->current_editor();
 }
 
-void open_file(DeprecatedString const& filename)
+void open_file(ByteString const& filename)
 {
     s_hack_studio_widget->open_file(filename);
 }
 
-void open_file(DeprecatedString const& filename, size_t line, size_t column)
+void open_file(ByteString const& filename, size_t line, size_t column)
 {
     s_hack_studio_widget->open_file(filename, line, column);
 }
@@ -175,7 +175,7 @@ Project& project()
     return s_hack_studio_widget->project();
 }
 
-DeprecatedString currently_open_file()
+ByteString currently_open_file()
 {
     if (!s_hack_studio_widget)
         return {};
@@ -212,16 +212,16 @@ bool semantic_syntax_highlighting_is_enabled()
 
 static ErrorOr<NonnullRefPtr<HackStudioWidget>> create_hack_studio_widget(bool mode_coredump, StringView raw_path_argument, pid_t pid_to_debug)
 {
-    DeprecatedString project_path;
+    ByteString project_path;
     if (pid_to_debug != -1 || mode_coredump)
         project_path = "/usr/src/serenity";
     else if (!raw_path_argument.is_null())
         // FIXME: Validation is unintentional, and should be removed when migrating to String.
-        project_path = TRY(DeprecatedString::from_utf8(raw_path_argument));
+        project_path = TRY(ByteString::from_utf8(raw_path_argument));
     else if (auto last_path = last_opened_project_path(); last_path.has_value())
         project_path = last_path.release_value();
     else
-        project_path = TRY(FileSystem::real_path("."sv)).to_deprecated_string();
+        project_path = TRY(FileSystem::real_path("."sv)).to_byte_string();
 
     return HackStudioWidget::create(project_path);
 }
diff --git a/Userland/DevTools/Profiler/DisassemblyModel.cpp b/Userland/DevTools/Profiler/DisassemblyModel.cpp
index 9d8618bd798..be5c7672b2f 100644
--- a/Userland/DevTools/Profiler/DisassemblyModel.cpp
+++ b/Userland/DevTools/Profiler/DisassemblyModel.cpp
@@ -51,7 +51,7 @@ DisassemblyModel::DisassemblyModel(Profile& profile, ProfileNode& node)
         if (elf == nullptr)
             return;
         if (g_kernel_debug_info == nullptr)
-            g_kernel_debug_info = make<Debug::DebugInfo>(g_kernel_debuginfo_object->elf, DeprecatedString::empty(), base_address);
+            g_kernel_debug_info = make<Debug::DebugInfo>(g_kernel_debuginfo_object->elf, ByteString::empty(), base_address);
         debug_info = g_kernel_debug_info.ptr();
     } else {
         auto const& process = node.process();
@@ -114,7 +114,7 @@ DisassemblyModel::DisassemblyModel(Profile& profile, ProfileNode& node)
             break;
         FlatPtr address_in_profiled_program = node.address() + offset_into_symbol;
 
-        auto disassembly = insn.value().to_deprecated_string(address_in_profiled_program, &symbol_provider);
+        auto disassembly = insn.value().to_byte_string(address_in_profiled_program, &symbol_provider);
 
         StringView instruction_bytes = view.substring_view(offset_into_symbol, insn.value().length());
         u32 samples_at_this_instruction = m_node.events_per_address().get(address_in_profiled_program).value_or(0);
@@ -200,14 +200,14 @@ GUI::Variant DisassemblyModel::data(GUI::ModelIndex const& index, GUI::ModelRole
         }
 
         if (index.column() == Column::Address)
-            return DeprecatedString::formatted("{:p}", insn.address);
+            return ByteString::formatted("{:p}", insn.address);
 
         if (index.column() == Column::InstructionBytes) {
             StringBuilder builder;
             for (auto ch : insn.bytes) {
                 builder.appendff("{:02x} ", (u8)ch);
             }
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         }
 
         if (index.column() == Column::Disassembly)
@@ -229,7 +229,7 @@ GUI::Variant DisassemblyModel::data(GUI::ModelIndex const& index, GUI::ModelRole
                 auto const& entry = insn.source_position_with_inlines.source_position.value();
                 builder.appendff("{}:{}", entry.file_path, entry.line_number);
             }
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         }
 
         return {};
diff --git a/Userland/DevTools/Profiler/DisassemblyModel.h b/Userland/DevTools/Profiler/DisassemblyModel.h
index 1c301faecab..038298e5639 100644
--- a/Userland/DevTools/Profiler/DisassemblyModel.h
+++ b/Userland/DevTools/Profiler/DisassemblyModel.h
@@ -18,7 +18,7 @@ class ProfileNode;
 
 struct InstructionData {
     X86::Instruction insn;
-    DeprecatedString disassembly;
+    ByteString disassembly;
     StringView bytes;
     FlatPtr address { 0 };
     u32 event_count { 0 };
diff --git a/Userland/DevTools/Profiler/FilesystemEventModel.cpp b/Userland/DevTools/Profiler/FilesystemEventModel.cpp
index 8e9d9476507..80e844a0409 100644
--- a/Userland/DevTools/Profiler/FilesystemEventModel.cpp
+++ b/Userland/DevTools/Profiler/FilesystemEventModel.cpp
@@ -32,7 +32,7 @@ Duration FileEventNode::total_duration() const
     return m_open.duration + m_close.duration + m_readv.duration + m_read.duration + m_pread.duration;
 }
 
-FileEventNode& FileEventNode::find_or_create_node(DeprecatedString const& searched_path)
+FileEventNode& FileEventNode::find_or_create_node(ByteString const& searched_path)
 {
     // TODO: Optimize this function.
     if (searched_path == ""sv || searched_path == "/"sv) {
@@ -45,7 +45,7 @@ FileEventNode& FileEventNode::find_or_create_node(DeprecatedString const& search
 
     StringBuilder sb;
     sb.join('/', parts);
-    auto new_s = sb.to_deprecated_string();
+    auto new_s = sb.to_byte_string();
 
     for (auto& child : m_children) {
         if (child->m_path == current) {
@@ -70,7 +70,7 @@ FileEventNode& FileEventNode::find_or_create_node(DeprecatedString const& search
     }
 }
 
-FileEventNode& FileEventNode::create_recursively(DeprecatedString new_path)
+FileEventNode& FileEventNode::create_recursively(ByteString new_path)
 {
     auto const lex_path = LexicalPath(new_path);
     auto parts = lex_path.parts();
@@ -86,7 +86,7 @@ FileEventNode& FileEventNode::create_recursively(DeprecatedString new_path)
         StringBuilder sb;
         sb.join('/', parts);
 
-        return new_node->create_recursively(sb.to_deprecated_string());
+        return new_node->create_recursively(sb.to_byte_string());
     }
 }
 
diff --git a/Userland/DevTools/Profiler/FilesystemEventModel.h b/Userland/DevTools/Profiler/FilesystemEventModel.h
index c80b3070296..80e45693771 100644
--- a/Userland/DevTools/Profiler/FilesystemEventModel.h
+++ b/Userland/DevTools/Profiler/FilesystemEventModel.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/LexicalPath.h>
 #include <AK/Time.h>
@@ -18,23 +18,23 @@ class Profile;
 
 class FileEventNode : public RefCounted<FileEventNode> {
 public:
-    static NonnullRefPtr<FileEventNode> create(DeprecatedString const& path, FileEventNode* parent = nullptr)
+    static NonnullRefPtr<FileEventNode> create(ByteString const& path, FileEventNode* parent = nullptr)
     {
         return adopt_ref(*new FileEventNode(path, parent));
     }
 
-    FileEventNode& find_or_create_node(DeprecatedString const&);
+    FileEventNode& find_or_create_node(ByteString const&);
 
     Vector<NonnullRefPtr<FileEventNode>>& children() { return m_children; }
     Vector<NonnullRefPtr<FileEventNode>> const& children() const { return m_children; }
 
     FileEventNode* parent() { return m_parent; }
 
-    FileEventNode& create_recursively(DeprecatedString);
+    FileEventNode& create_recursively(ByteString);
 
     void for_each_parent_node(Function<void(FileEventNode&)> callback);
 
-    DeprecatedString const& path() const { return m_path; }
+    ByteString const& path() const { return m_path; }
 
     u64 total_count() const;
     Duration total_duration() const;
@@ -51,11 +51,11 @@ public:
     FileEventType& pread() { return m_pread; }
 
 private:
-    FileEventNode(DeprecatedString const& path, FileEventNode* parent = nullptr)
+    FileEventNode(ByteString const& path, FileEventNode* parent = nullptr)
         : m_path(path)
         , m_parent(parent) {};
 
-    DeprecatedString m_path;
+    ByteString m_path;
 
     FileEventType m_open;
     FileEventType m_close;
diff --git a/Userland/DevTools/Profiler/FlameGraphView.cpp b/Userland/DevTools/Profiler/FlameGraphView.cpp
index 4b70f31f3d6..c59f69d8970 100644
--- a/Userland/DevTools/Profiler/FlameGraphView.cpp
+++ b/Userland/DevTools/Profiler/FlameGraphView.cpp
@@ -180,7 +180,7 @@ String FlameGraphView::bar_label(StackBar const& bar) const
     auto label_index = bar.index.sibling_at_column(m_text_column);
     String label = "All"_string;
     if (label_index.is_valid()) {
-        label = MUST(String::from_deprecated_string(m_model.data(label_index).to_deprecated_string()));
+        label = MUST(String::from_byte_string(m_model.data(label_index).to_byte_string()));
     }
     return label;
 }
diff --git a/Userland/DevTools/Profiler/IndividualSampleModel.cpp b/Userland/DevTools/Profiler/IndividualSampleModel.cpp
index fb3fb06cfe2..e4d587f80a9 100644
--- a/Userland/DevTools/Profiler/IndividualSampleModel.cpp
+++ b/Userland/DevTools/Profiler/IndividualSampleModel.cpp
@@ -50,7 +50,7 @@ GUI::Variant IndividualSampleModel::data(GUI::ModelIndex const& index, GUI::Mode
 
     if (role == GUI::ModelRole::Display) {
         if (index.column() == Column::Address)
-            return DeprecatedString::formatted("{:p}", frame.address);
+            return ByteString::formatted("{:p}", frame.address);
 
         if (index.column() == Column::Symbol) {
             return frame.symbol;
diff --git a/Userland/DevTools/Profiler/PercentageFormatting.h b/Userland/DevTools/Profiler/PercentageFormatting.h
index 7d9716fd83d..b3d2fe91ad5 100644
--- a/Userland/DevTools/Profiler/PercentageFormatting.h
+++ b/Userland/DevTools/Profiler/PercentageFormatting.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/IntegralMath.h>
 #include <AK/Math.h>
 
@@ -16,10 +16,10 @@ namespace Profiler {
 static constexpr int const number_of_percent_digits = 2;
 static constexpr int const percent_digits_rounding = AK::pow(10, number_of_percent_digits);
 
-DeprecatedString format_percentage(auto value, auto total)
+ByteString format_percentage(auto value, auto total)
 {
     auto percentage_full_precision = round_to<u64>(value * 100.f / total * percent_digits_rounding);
-    return DeprecatedString::formatted(
+    return ByteString::formatted(
         "{}.{:02}",
         percentage_full_precision / percent_digits_rounding,
         percentage_full_precision % percent_digits_rounding);
diff --git a/Userland/DevTools/Profiler/Process.cpp b/Userland/DevTools/Profiler/Process.cpp
index b21b2f45de1..dd4fcdbeba5 100644
--- a/Userland/DevTools/Profiler/Process.cpp
+++ b/Userland/DevTools/Profiler/Process.cpp
@@ -41,9 +41,9 @@ void Process::handle_thread_exit(pid_t tid, EventSerialNumber serial)
     thread->end_valid = serial;
 }
 
-HashMap<DeprecatedString, OwnPtr<MappedObject>> g_mapped_object_cache;
+HashMap<ByteString, OwnPtr<MappedObject>> g_mapped_object_cache;
 
-static MappedObject* get_or_create_mapped_object(DeprecatedString const& path)
+static MappedObject* get_or_create_mapped_object(ByteString const& path)
 {
     if (auto it = g_mapped_object_cache.find(path); it != g_mapped_object_cache.end())
         return it->value.ptr();
@@ -67,7 +67,7 @@ static MappedObject* get_or_create_mapped_object(DeprecatedString const& path)
     return ptr;
 }
 
-void LibraryMetadata::handle_mmap(FlatPtr base, size_t size, DeprecatedString const& name)
+void LibraryMetadata::handle_mmap(FlatPtr base, size_t size, ByteString const& name)
 {
     StringView path;
     if (name.contains("Loader.so"sv))
@@ -82,25 +82,25 @@ void LibraryMetadata::handle_mmap(FlatPtr base, size_t size, DeprecatedString co
     // associated base address and size as new regions are discovered.
 
     // We don't allocate a temporary String object if an entry already exists.
-    // This assumes that DeprecatedString::hash and StringView::hash return the same result.
+    // This assumes that ByteString::hash and StringView::hash return the same result.
     auto string_view_compare = [&path](auto& entry) { return path == entry.key.view(); };
     if (auto existing_it = m_libraries.find(path.hash(), string_view_compare); existing_it != m_libraries.end()) {
         auto& entry = *existing_it->value;
         entry.base = min(entry.base, base);
         entry.size = max(entry.size + size, base - entry.base + size);
     } else {
-        DeprecatedString path_string = path.to_deprecated_string();
-        DeprecatedString full_path;
+        ByteString path_string = path.to_byte_string();
+        ByteString full_path;
         if (path_string.starts_with('/'))
             full_path = path_string;
         else if (FileSystem::looks_like_shared_library(path_string))
-            full_path = DeprecatedString::formatted("/usr/lib/{}", path);
+            full_path = ByteString::formatted("/usr/lib/{}", path);
         else
             full_path = path_string;
 
         auto* mapped_object = get_or_create_mapped_object(full_path);
         if (!mapped_object) {
-            full_path = DeprecatedString::formatted("/usr/local/lib/{}", path);
+            full_path = ByteString::formatted("/usr/local/lib/{}", path);
             mapped_object = get_or_create_mapped_object(full_path);
             if (!mapped_object)
                 return;
@@ -112,14 +112,14 @@ void LibraryMetadata::handle_mmap(FlatPtr base, size_t size, DeprecatedString co
 Debug::DebugInfo const& LibraryMetadata::Library::load_debug_info(FlatPtr base_address) const
 {
     if (debug_info == nullptr)
-        debug_info = make<Debug::DebugInfo>(object->elf, DeprecatedString::empty(), base_address);
+        debug_info = make<Debug::DebugInfo>(object->elf, ByteString::empty(), base_address);
     return *debug_info.ptr();
 }
 
-DeprecatedString LibraryMetadata::Library::symbolicate(FlatPtr ptr, u32* offset) const
+ByteString LibraryMetadata::Library::symbolicate(FlatPtr ptr, u32* offset) const
 {
     if (!object)
-        return DeprecatedString::formatted("?? <{:p}>", ptr);
+        return ByteString::formatted("?? <{:p}>", ptr);
 
     return object->elf.symbolicate(ptr - base, offset);
 }
diff --git a/Userland/DevTools/Profiler/Process.h b/Userland/DevTools/Profiler/Process.h
index 064ca69f2b4..e1ee2080908 100644
--- a/Userland/DevTools/Profiler/Process.h
+++ b/Userland/DevTools/Profiler/Process.h
@@ -21,27 +21,27 @@ struct MappedObject {
     ELF::Image elf;
 };
 
-extern HashMap<DeprecatedString, OwnPtr<MappedObject>> g_mapped_object_cache;
+extern HashMap<ByteString, OwnPtr<MappedObject>> g_mapped_object_cache;
 
 class LibraryMetadata {
 public:
     struct Library {
         FlatPtr base;
         size_t size;
-        DeprecatedString name;
+        ByteString name;
         MappedObject* object { nullptr };
         // This is loaded lazily because we only need it in disassembly view
         mutable OwnPtr<Debug::DebugInfo> debug_info;
 
-        DeprecatedString symbolicate(FlatPtr, u32* offset) const;
+        ByteString symbolicate(FlatPtr, u32* offset) const;
         Debug::DebugInfo const& load_debug_info(FlatPtr base_address) const;
     };
 
-    void handle_mmap(FlatPtr base, size_t size, DeprecatedString const& name);
+    void handle_mmap(FlatPtr base, size_t size, ByteString const& name);
     Library const* library_containing(FlatPtr) const;
 
 private:
-    mutable HashMap<DeprecatedString, NonnullOwnPtr<Library>> m_libraries;
+    mutable HashMap<ByteString, NonnullOwnPtr<Library>> m_libraries;
 };
 
 struct Thread {
@@ -57,8 +57,8 @@ struct Thread {
 
 struct Process {
     pid_t pid {};
-    DeprecatedString executable;
-    DeprecatedString basename;
+    ByteString executable;
+    ByteString basename;
     HashMap<int, Vector<Thread>> threads {};
     LibraryMetadata library_metadata {};
     EventSerialNumber start_valid;
diff --git a/Userland/DevTools/Profiler/Profile.cpp b/Userland/DevTools/Profiler/Profile.cpp
index f665227c153..ce8b6200c7e 100644
--- a/Userland/DevTools/Profiler/Profile.cpp
+++ b/Userland/DevTools/Profiler/Profile.cpp
@@ -289,10 +289,10 @@ ErrorOr<NonnullOwnPtr<Profile>> Profile::load_from_perfcore_file(StringView path
         return Error::from_string_literal("Malformed profile (strings is not an array)");
     auto const& strings = strings_value.value();
 
-    HashMap<FlatPtr, DeprecatedString> profile_strings;
+    HashMap<FlatPtr, ByteString> profile_strings;
     for (FlatPtr string_id = 0; string_id < strings.size(); ++string_id) {
         auto const& value = strings.at(string_id);
-        profile_strings.set(string_id, value.to_deprecated_string());
+        profile_strings.set(string_id, value.to_byte_string());
     }
 
     auto events_value = object.get_array("events"sv);
@@ -317,7 +317,7 @@ ErrorOr<NonnullOwnPtr<Profile>> Profile::load_from_perfcore_file(StringView path
         event.pid = perf_event.get_i32("pid"sv).value_or(0);
         event.tid = perf_event.get_i32("tid"sv).value_or(0);
 
-        auto type_string = perf_event.get_deprecated_string("type"sv).value_or({});
+        auto type_string = perf_event.get_byte_string("type"sv).value_or({});
 
         if (type_string == "sample"sv) {
             event.data = Event::SampleData {};
@@ -333,13 +333,13 @@ ErrorOr<NonnullOwnPtr<Profile>> Profile::load_from_perfcore_file(StringView path
         } else if (type_string == "signpost"sv) {
             auto string_id = perf_event.get_addr("arg1"sv).value_or(0);
             event.data = Event::SignpostData {
-                .string = profile_strings.get(string_id).value_or(DeprecatedString::formatted("Signpost #{}", string_id)),
+                .string = profile_strings.get(string_id).value_or(ByteString::formatted("Signpost #{}", string_id)),
                 .arg = perf_event.get_addr("arg2"sv).value_or(0),
             };
         } else if (type_string == "mmap"sv) {
             auto ptr = perf_event.get_addr("ptr"sv).value_or(0);
             auto size = perf_event.get_integer<size_t>("size"sv).value_or(0);
-            auto name = perf_event.get_deprecated_string("name"sv).value_or({});
+            auto name = perf_event.get_byte_string("name"sv).value_or({});
 
             event.data = Event::MmapData {
                 .ptr = ptr,
@@ -359,7 +359,7 @@ ErrorOr<NonnullOwnPtr<Profile>> Profile::load_from_perfcore_file(StringView path
             continue;
         } else if (type_string == "process_create"sv) {
             auto parent_pid = perf_event.get_integer<pid_t>("parent_pid"sv).value_or(0);
-            auto executable = perf_event.get_deprecated_string("executable"sv).value_or({});
+            auto executable = perf_event.get_byte_string("executable"sv).value_or({});
             event.data = Event::ProcessCreateData {
                 .parent_pid = parent_pid,
                 .executable = executable,
@@ -377,7 +377,7 @@ ErrorOr<NonnullOwnPtr<Profile>> Profile::load_from_perfcore_file(StringView path
             all_processes.append(move(sampled_process));
             continue;
         } else if (type_string == "process_exec"sv) {
-            auto executable = perf_event.get_deprecated_string("executable"sv).value_or({});
+            auto executable = perf_event.get_byte_string("executable"sv).value_or({});
             event.data = Event::ProcessExecData {
                 .executable = executable,
             };
@@ -482,13 +482,13 @@ ErrorOr<NonnullOwnPtr<Profile>> Profile::load_from_perfcore_file(StringView path
             auto ptr = frame.to_number<u64>();
             u32 offset = 0;
             DeprecatedFlyString object_name;
-            DeprecatedString symbol;
+            ByteString symbol;
 
             if (maybe_kernel_base.has_value() && ptr >= maybe_kernel_base.value()) {
                 if (g_kernel_debuginfo_object.has_value()) {
                     symbol = g_kernel_debuginfo_object->elf.symbolicate(ptr - maybe_kernel_base.value(), &offset);
                 } else {
-                    symbol = DeprecatedString::formatted("?? <{:p}>", ptr);
+                    symbol = ByteString::formatted("?? <{:p}>", ptr);
                 }
             } else {
                 auto it = current_processes.find(event.pid);
@@ -500,7 +500,7 @@ ErrorOr<NonnullOwnPtr<Profile>> Profile::load_from_perfcore_file(StringView path
                     object_name = library->name;
                     symbol = library->symbolicate(ptr, &offset);
                 } else {
-                    symbol = DeprecatedString::formatted("?? <{:p}>", ptr);
+                    symbol = ByteString::formatted("?? <{:p}>", ptr);
                 }
             }
 
@@ -681,7 +681,7 @@ ProfileNode::ProfileNode(Process const& process)
 {
 }
 
-ProfileNode::ProfileNode(Process const& process, DeprecatedFlyString const& object_name, DeprecatedString symbol, FlatPtr address, u32 offset, u64 timestamp, pid_t pid)
+ProfileNode::ProfileNode(Process const& process, DeprecatedFlyString const& object_name, ByteString symbol, FlatPtr address, u32 offset, u64 timestamp, pid_t pid)
     : m_process(process)
     , m_symbol(move(symbol))
     , m_pid(pid)
@@ -689,7 +689,7 @@ ProfileNode::ProfileNode(Process const& process, DeprecatedFlyString const& obje
     , m_offset(offset)
     , m_timestamp(timestamp)
 {
-    DeprecatedString object;
+    ByteString object;
     if (object_name.ends_with(": .text"sv)) {
         object = object_name.view().substring_view(0, object_name.length() - 7);
     } else {
diff --git a/Userland/DevTools/Profiler/Profile.h b/Userland/DevTools/Profiler/Profile.h
index 74aa0f53f43..00d7c431440 100644
--- a/Userland/DevTools/Profiler/Profile.h
+++ b/Userland/DevTools/Profiler/Profile.h
@@ -35,7 +35,7 @@ extern OwnPtr<Debug::DebugInfo> g_kernel_debug_info;
 
 class ProfileNode : public RefCounted<ProfileNode> {
 public:
-    static NonnullRefPtr<ProfileNode> create(Process const& process, DeprecatedFlyString const& object_name, DeprecatedString symbol, FlatPtr address, u32 offset, u64 timestamp, pid_t pid)
+    static NonnullRefPtr<ProfileNode> create(Process const& process, DeprecatedFlyString const& object_name, ByteString symbol, FlatPtr address, u32 offset, u64 timestamp, pid_t pid)
     {
         return adopt_ref(*new ProfileNode(process, object_name, move(symbol), address, offset, timestamp, pid));
     }
@@ -55,7 +55,7 @@ public:
     void did_see_event(size_t event_index) { m_seen_events.set(event_index, true); }
 
     DeprecatedFlyString const& object_name() const { return m_object_name; }
-    DeprecatedString const& symbol() const { return m_symbol; }
+    ByteString const& symbol() const { return m_symbol; }
     FlatPtr address() const { return m_address; }
     u32 offset() const { return m_offset; }
     u64 timestamp() const { return m_timestamp; }
@@ -75,7 +75,7 @@ public:
         m_children.append(child);
     }
 
-    ProfileNode& find_or_create_child(DeprecatedFlyString const& object_name, DeprecatedString symbol, FlatPtr address, u32 offset, u64 timestamp, pid_t pid)
+    ProfileNode& find_or_create_child(DeprecatedFlyString const& object_name, ByteString symbol, FlatPtr address, u32 offset, u64 timestamp, pid_t pid)
     {
         for (size_t i = 0; i < m_children.size(); ++i) {
             auto& child = m_children[i];
@@ -113,13 +113,13 @@ public:
 
 private:
     explicit ProfileNode(Process const&);
-    explicit ProfileNode(Process const&, DeprecatedFlyString const& object_name, DeprecatedString symbol, FlatPtr address, u32 offset, u64 timestamp, pid_t);
+    explicit ProfileNode(Process const&, DeprecatedFlyString const& object_name, ByteString symbol, FlatPtr address, u32 offset, u64 timestamp, pid_t);
 
     bool m_root { false };
     Process const& m_process;
     ProfileNode* m_parent { nullptr };
     DeprecatedFlyString m_object_name;
-    DeprecatedString m_symbol;
+    ByteString m_symbol;
     pid_t m_pid { 0 };
     FlatPtr m_address { 0 };
     u32 m_offset { 0 };
@@ -168,7 +168,7 @@ public:
 
     struct Frame {
         DeprecatedFlyString object_name;
-        DeprecatedString symbol;
+        ByteString symbol;
         FlatPtr address { 0 };
         u32 offset { 0 };
     };
@@ -196,14 +196,14 @@ public:
         };
 
         struct SignpostData {
-            DeprecatedString string;
+            ByteString string;
             FlatPtr arg {};
         };
 
         struct MmapData {
             FlatPtr ptr {};
             size_t size {};
-            DeprecatedString name;
+            ByteString name;
         };
 
         struct MunmapData {
@@ -213,11 +213,11 @@ public:
 
         struct ProcessCreateData {
             pid_t parent_pid { 0 };
-            DeprecatedString executable;
+            ByteString executable;
         };
 
         struct ProcessExecData {
-            DeprecatedString executable;
+            ByteString executable;
         };
 
         struct ThreadCreateData {
@@ -227,31 +227,31 @@ public:
         // Based on Syscall::SC_open_params
         struct OpenEventData {
             int dirfd;
-            DeprecatedString path;
+            ByteString path;
             int options;
             u64 mode;
         };
 
         struct CloseEventData {
             int fd;
-            DeprecatedString path;
+            ByteString path;
         };
 
         struct ReadvEventData {
             int fd;
-            DeprecatedString path;
+            ByteString path;
             // struct iovec* iov; // TODO: Implement
             // int iov_count; // TODO: Implement
         };
 
         struct ReadEventData {
             int fd;
-            DeprecatedString path;
+            ByteString path;
         };
 
         struct PreadEventData {
             int fd;
-            DeprecatedString path;
+            ByteString path;
             FlatPtr buffer_ptr;
             size_t size;
             off_t offset;
diff --git a/Userland/DevTools/Profiler/ProfileModel.cpp b/Userland/DevTools/Profiler/ProfileModel.cpp
index cb09e01bdce..464faacb00f 100644
--- a/Userland/DevTools/Profiler/ProfileModel.cpp
+++ b/Userland/DevTools/Profiler/ProfileModel.cpp
@@ -126,7 +126,7 @@ GUI::Variant ProfileModel::data(GUI::ModelIndex const& index, GUI::ModelRole rol
             return node->object_name();
         if (index.column() == Column::StackFrame) {
             if (node->is_root()) {
-                return DeprecatedString::formatted("{} ({})", node->process().basename, node->process().pid);
+                return ByteString::formatted("{} ({})", node->process().basename, node->process().pid);
             }
             return node->symbol();
         }
@@ -136,7 +136,7 @@ GUI::Variant ProfileModel::data(GUI::ModelIndex const& index, GUI::ModelRole rol
             auto const* library = node->process().library_metadata.library_containing(node->address());
             if (!library)
                 return "";
-            return DeprecatedString::formatted("{:p} (offset {:p})", node->address(), node->address() - library->base);
+            return ByteString::formatted("{:p} (offset {:p})", node->address(), node->address() - library->base);
         }
         return {};
     }
diff --git a/Userland/DevTools/Profiler/SourceModel.cpp b/Userland/DevTools/Profiler/SourceModel.cpp
index ae8bd2043b7..def4c06a234 100644
--- a/Userland/DevTools/Profiler/SourceModel.cpp
+++ b/Userland/DevTools/Profiler/SourceModel.cpp
@@ -17,7 +17,7 @@ namespace Profiler {
 class SourceFile final {
 public:
     struct Line {
-        DeprecatedString content;
+        ByteString content;
         size_t num_samples { 0 };
     };
 
@@ -25,7 +25,7 @@ public:
 
     SourceFile(StringView filename)
     {
-        DeprecatedString source_file_name = filename.replace("../../"sv, source_root_path, ReplaceMode::FirstOnly);
+        ByteString source_file_name = filename.replace("../../"sv, source_root_path, ReplaceMode::FirstOnly);
 
         auto try_read_lines = [&]() -> ErrorOr<void> {
             auto unbuffered_file = TRY(Core::File::open(source_file_name, Core::File::OpenMode::Read));
@@ -70,7 +70,7 @@ SourceModel::SourceModel(Profile& profile, ProfileNode& node)
             return;
         base_address = maybe_kernel_base.release_value();
         if (g_kernel_debug_info == nullptr)
-            g_kernel_debug_info = make<Debug::DebugInfo>(g_kernel_debuginfo_object->elf, DeprecatedString::empty(), base_address);
+            g_kernel_debug_info = make<Debug::DebugInfo>(g_kernel_debuginfo_object->elf, ByteString::empty(), base_address);
         debug_info = g_kernel_debug_info.ptr();
     } else {
         auto const& process = node.process();
@@ -86,7 +86,7 @@ SourceModel::SourceModel(Profile& profile, ProfileNode& node)
     VERIFY(debug_info != nullptr);
 
     // Try to read all source files contributing to the selected function and aggregate the samples by line.
-    HashMap<DeprecatedString, SourceFile> source_files;
+    HashMap<ByteString, SourceFile> source_files;
     for (auto const& pair : node.events_per_address()) {
         auto position = debug_info->get_source_position(pair.key - base_address);
         if (position.has_value()) {
diff --git a/Userland/DevTools/Profiler/SourceModel.h b/Userland/DevTools/Profiler/SourceModel.h
index af85480a4a2..396c1a4499a 100644
--- a/Userland/DevTools/Profiler/SourceModel.h
+++ b/Userland/DevTools/Profiler/SourceModel.h
@@ -16,9 +16,9 @@ class ProfileNode;
 struct SourceLineData {
     u32 event_count { 0 };
     float percent { 0 };
-    DeprecatedString location;
+    ByteString location;
     u32 line_number { 0 };
-    DeprecatedString source_code;
+    ByteString source_code;
 };
 
 class SourceModel final : public GUI::Model {
diff --git a/Userland/DevTools/Profiler/TimelineHeader.cpp b/Userland/DevTools/Profiler/TimelineHeader.cpp
index 34c9367f1af..d8128459ca3 100644
--- a/Userland/DevTools/Profiler/TimelineHeader.cpp
+++ b/Userland/DevTools/Profiler/TimelineHeader.cpp
@@ -24,7 +24,7 @@ TimelineHeader::TimelineHeader(Profile& profile, Process const& process)
     update_selection();
 
     m_icon = GUI::FileIconProvider::icon_for_executable(m_process.executable).bitmap_for_size(32);
-    m_text = DeprecatedString::formatted("{} ({})", LexicalPath::basename(m_process.executable), m_process.pid);
+    m_text = ByteString::formatted("{} ({})", LexicalPath::basename(m_process.executable), m_process.pid);
 }
 
 void TimelineHeader::paint_event(GUI::PaintEvent& event)
diff --git a/Userland/DevTools/Profiler/TimelineHeader.h b/Userland/DevTools/Profiler/TimelineHeader.h
index 334afdbb664..a4a0e0c198e 100644
--- a/Userland/DevTools/Profiler/TimelineHeader.h
+++ b/Userland/DevTools/Profiler/TimelineHeader.h
@@ -33,7 +33,7 @@ private:
     Profile& m_profile;
     Process const& m_process;
     RefPtr<Gfx::Bitmap const> m_icon;
-    DeprecatedString m_text;
+    ByteString m_text;
     bool m_selected;
 };
 
diff --git a/Userland/DevTools/Profiler/main.cpp b/Userland/DevTools/Profiler/main.cpp
index 5b0a2c2a701..0d2d43caf61 100644
--- a/Userland/DevTools/Profiler/main.cpp
+++ b/Userland/DevTools/Profiler/main.cpp
@@ -62,18 +62,18 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto app = TRY(GUI::Application::create(arguments));
     auto app_icon = TRY(GUI::Icon::try_create_default_icon("app-profiler"sv));
 
-    DeprecatedString perfcore_file;
+    ByteString perfcore_file;
     if (perfcore_file_arg.is_empty()) {
         if (!generate_profile(pid))
             return 0;
-        perfcore_file = DeprecatedString::formatted("/proc/{}/perf_events", pid);
+        perfcore_file = ByteString::formatted("/proc/{}/perf_events", pid);
     } else {
         perfcore_file = perfcore_file_arg;
     }
 
     auto profile_or_error = Profile::load_from_perfcore_file(perfcore_file);
     if (profile_or_error.is_error()) {
-        GUI::MessageBox::show(nullptr, DeprecatedString::formatted("{}", profile_or_error.error()), "Profiler"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(nullptr, ByteString::formatted("{}", profile_or_error.error()), "Profiler"sv, GUI::MessageBox::Type::Error);
         return 0;
     }
 
@@ -224,8 +224,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     // FIXME: Make this constexpr once String is able to.
     auto const format_sample_count = [&profile](auto const sample_count) {
         if (profile->show_percentages())
-            return DeprecatedString::formatted("{}%", sample_count.as_string());
-        return DeprecatedString::formatted("{} Samples", sample_count.to_i32());
+            return ByteString::formatted("{}%", sample_count.as_string());
+        return ByteString::formatted("{} Samples", sample_count.to_i32());
     };
 
     auto& statusbar = main_widget->add<GUI::Statusbar>();
@@ -235,7 +235,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         auto flamegraph_hovered_index = flamegraph_view.hovered_index();
         if (flamegraph_hovered_index.is_valid()) {
-            auto stack = profile->model().data(flamegraph_hovered_index.sibling_at_column(ProfileModel::Column::StackFrame)).to_deprecated_string();
+            auto stack = profile->model().data(flamegraph_hovered_index.sibling_at_column(ProfileModel::Column::StackFrame)).to_byte_string();
             auto sample_count = profile->model().data(flamegraph_hovered_index.sibling_at_column(ProfileModel::Column::SampleCount));
             auto self_count = profile->model().data(flamegraph_hovered_index.sibling_at_column(ProfileModel::Column::SelfCount));
             builder.appendff("{}, ", stack);
@@ -312,10 +312,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     return app->exec();
 }
 
-static bool prompt_to_stop_profiling(pid_t pid, DeprecatedString const& process_name)
+static bool prompt_to_stop_profiling(pid_t pid, ByteString const& process_name)
 {
     auto window = GUI::Window::construct();
-    window->set_title(DeprecatedString::formatted("Profiling {}({})", process_name, pid));
+    window->set_title(ByteString::formatted("Profiling {}({})", process_name, pid));
     window->resize(240, 100);
     window->set_icon(Gfx::Bitmap::load_from_file("/res/icons/16x16/app-profiler.png"sv).release_value_but_fixme_should_propagate_errors());
     window->center_on_screen();
@@ -351,7 +351,7 @@ bool generate_profile(pid_t& pid)
         pid = process_chooser->pid();
     }
 
-    DeprecatedString process_name;
+    ByteString process_name;
 
     auto all_processes = Core::ProcessStatisticsReader::get_all();
     if (!all_processes.is_error()) {
@@ -369,7 +369,7 @@ bool generate_profile(pid_t& pid)
 
     if (profiling_enable(pid, event_mask) < 0) {
         int saved_errno = errno;
-        GUI::MessageBox::show(nullptr, DeprecatedString::formatted("Unable to profile process {}({}): {}", process_name, pid, strerror(saved_errno)), "Profiler"sv, GUI::MessageBox::Type::Error);
+        GUI::MessageBox::show(nullptr, ByteString::formatted("Unable to profile process {}({}): {}", process_name, pid, strerror(saved_errno)), "Profiler"sv, GUI::MessageBox::Type::Error);
         return false;
     }
 
diff --git a/Userland/DevTools/SQLStudio/MainWidget.cpp b/Userland/DevTools/SQLStudio/MainWidget.cpp
index 27c3db4ede0..6de96c655d2 100644
--- a/Userland/DevTools/SQLStudio/MainWidget.cpp
+++ b/Userland/DevTools/SQLStudio/MainWidget.cpp
@@ -41,16 +41,16 @@ REGISTER_WIDGET(SQLStudio, MainWidget);
 
 namespace SQLStudio {
 
-static Vector<DeprecatedString> lookup_database_names()
+static Vector<ByteString> lookup_database_names()
 {
     static constexpr auto database_extension = ".db"sv;
 
-    auto database_path = DeprecatedString::formatted("{}/sql", Core::StandardPaths::data_directory());
+    auto database_path = ByteString::formatted("{}/sql", Core::StandardPaths::data_directory());
     if (!FileSystem::exists(database_path))
         return {};
 
     Core::DirIterator iterator(move(database_path), Core::DirIterator::SkipParentAndBaseDir);
-    Vector<DeprecatedString> database_names;
+    Vector<ByteString> database_names;
 
     while (iterator.has_next()) {
         if (auto database = iterator.next_path(); database.ends_with(database_extension))
@@ -86,7 +86,7 @@ ErrorOr<void> MainWidget::setup()
         VERIFY(editor);
 
         if (auto result = editor->save(); result.is_error())
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to save {}\n{}", editor->path(), result.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to save {}\n{}", editor->path(), result.error()));
     });
 
     m_save_as_action = GUI::CommonActions::make_save_as_action([&](auto&) {
@@ -94,7 +94,7 @@ ErrorOr<void> MainWidget::setup()
         VERIFY(editor);
 
         if (auto result = editor->save_as(); result.is_error())
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to save {}\n{}", editor->path(), result.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to save {}\n{}", editor->path(), result.error()));
     });
 
     m_save_all_action = GUI::Action::create("Save All", { Mod_Ctrl | Mod_Alt, Key_S }, [this](auto&) {
@@ -106,7 +106,7 @@ ErrorOr<void> MainWidget::setup()
             m_tab_widget->set_active_widget(&editor);
 
             if (auto result = editor.save(); result.is_error()) {
-                GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to save {}\n{}", editor.path(), result.error()));
+                GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to save {}\n{}", editor.path(), result.error()));
                 return IterationDecision::Break;
             } else if (!result.value()) {
                 return IterationDecision::Break;
@@ -176,7 +176,7 @@ ErrorOr<void> MainWidget::setup()
             m_connection_id = *connection_id;
             m_run_script_action->set_enabled(true);
         } else {
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Could not connect to {}", database_name));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Could not connect to {}", database_name));
         }
     });
 
@@ -191,7 +191,7 @@ ErrorOr<void> MainWidget::setup()
     m_databases_combo_box = GUI::ComboBox::construct();
     m_databases_combo_box->set_editor_placeholder("Enter new database or select existing database"sv);
     m_databases_combo_box->set_max_width(font().width(m_databases_combo_box->editor_placeholder()) + font().max_glyph_width() + 16);
-    m_databases_combo_box->set_model(*GUI::ItemListModel<DeprecatedString>::create(database_names));
+    m_databases_combo_box->set_model(*GUI::ItemListModel<ByteString>::create(database_names));
     m_databases_combo_box->on_return_pressed = [this]() {
         m_connect_to_database_action->activate(m_databases_combo_box);
     };
@@ -220,7 +220,7 @@ ErrorOr<void> MainWidget::setup()
         auto& editor = verify_cast<ScriptEditor>(widget);
 
         if (auto result = editor.attempt_to_close(); result.is_error()) {
-            GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to save {}\n{}", editor.path(), result.error()));
+            GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to save {}\n{}", editor.path(), result.error()));
         } else if (result.value()) {
             m_tab_widget->remove_tab(editor);
             update_title();
@@ -266,14 +266,14 @@ ErrorOr<void> MainWidget::setup()
         auto* editor = active_editor();
         VERIFY(editor);
 
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Error executing {}\n{}", editor->path(), result.error_message));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Error executing {}\n{}", editor->path(), result.error_message));
     };
     m_sql_client->on_next_result = [this](auto result) {
         m_results.append({});
         m_results.last().ensure_capacity(result.values.size());
 
         for (auto const& value : result.values)
-            m_results.last().unchecked_append(value.to_deprecated_string());
+            m_results.last().unchecked_append(value.to_byte_string());
     };
     m_sql_client->on_results_exhausted = [this](auto) {
         if (m_results.size() == 0)
@@ -283,7 +283,7 @@ ErrorOr<void> MainWidget::setup()
 
         Vector<GUI::JsonArrayModel::FieldSpec> query_result_fields;
         for (auto& column_name : m_result_column_names)
-            query_result_fields.empend(column_name, String::from_deprecated_string(column_name).release_value_but_fixme_should_propagate_errors(), Gfx::TextAlignment::CenterLeft);
+            query_result_fields.empend(column_name, String::from_byte_string(column_name).release_value_but_fixme_should_propagate_errors(), Gfx::TextAlignment::CenterLeft);
 
         auto query_results_model = GUI::JsonArrayModel::create("{}", move(query_result_fields));
         m_query_results_table_view->set_model(MUST(GUI::SortingProxyModel::create(*query_results_model)));
@@ -333,10 +333,10 @@ ErrorOr<void> MainWidget::initialize_menu(GUI::Window* window)
 
 void MainWidget::open_new_script()
 {
-    auto new_script_name = DeprecatedString::formatted("New Script - {}", m_new_script_counter);
+    auto new_script_name = ByteString::formatted("New Script - {}", m_new_script_counter);
     ++m_new_script_counter;
 
-    auto& editor = m_tab_widget->add_tab<ScriptEditor>(String::from_deprecated_string(new_script_name).release_value_but_fixme_should_propagate_errors());
+    auto& editor = m_tab_widget->add_tab<ScriptEditor>(String::from_byte_string(new_script_name).release_value_but_fixme_should_propagate_errors());
     editor.new_script_with_temp_name(new_script_name);
 
     editor.on_cursor_change = [this] { on_editor_change(); };
@@ -351,7 +351,7 @@ void MainWidget::open_script_from_file(LexicalPath const& file_path)
     auto& editor = m_tab_widget->add_tab<ScriptEditor>(String::from_utf8(file_path.title()).release_value_but_fixme_should_propagate_errors());
 
     if (auto result = editor.open_script_from_file(file_path); result.is_error()) {
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to open {}\n{}", file_path, result.error()));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to open {}\n{}", file_path, result.error()));
         return;
     }
 
@@ -407,7 +407,7 @@ ScriptEditor* MainWidget::active_editor()
 void MainWidget::update_title()
 {
     if (auto* editor = active_editor())
-        window()->set_title(DeprecatedString::formatted("{} - SQL Studio", editor->name()));
+        window()->set_title(ByteString::formatted("{} - SQL Studio", editor->name()));
     else
         window()->set_title("SQL Studio");
 }
@@ -548,7 +548,7 @@ void MainWidget::read_next_sql_statement_of_editor()
             m_editor_line_level = last_token_ended_statement ? 0 : (m_editor_line_level > 0 ? m_editor_line_level : 1);
     } while ((m_editor_line_level > 0) || piece.is_empty());
 
-    auto sql_statement = piece.to_deprecated_string();
+    auto sql_statement = piece.to_byte_string();
 
     if (auto statement_id = m_sql_client->prepare_statement(*m_connection_id, sql_statement); statement_id.has_value()) {
         m_sql_client->async_execute_statement(*statement_id, {});
@@ -556,11 +556,11 @@ void MainWidget::read_next_sql_statement_of_editor()
         auto* editor = active_editor();
         VERIFY(editor);
 
-        GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Could not parse {}\n{}", editor->path(), sql_statement));
+        GUI::MessageBox::show_error(window(), ByteString::formatted("Could not parse {}\n{}", editor->path(), sql_statement));
     }
 }
 
-Optional<DeprecatedString> MainWidget::read_next_line_of_editor()
+Optional<ByteString> MainWidget::read_next_line_of_editor()
 {
     auto* editor = active_editor();
     if (!editor)
diff --git a/Userland/DevTools/SQLStudio/MainWidget.h b/Userland/DevTools/SQLStudio/MainWidget.h
index 76058555a5c..dfb9b4f9515 100644
--- a/Userland/DevTools/SQLStudio/MainWidget.h
+++ b/Userland/DevTools/SQLStudio/MainWidget.h
@@ -65,11 +65,11 @@ private:
 
     RefPtr<SQL::SQLClient> m_sql_client;
     Optional<SQL::ConnectionID> m_connection_id;
-    Vector<DeprecatedString> m_result_column_names;
-    Vector<Vector<DeprecatedString>> m_results;
+    Vector<ByteString> m_result_column_names;
+    Vector<Vector<ByteString>> m_results;
 
     void read_next_sql_statement_of_editor();
-    Optional<DeprecatedString> read_next_line_of_editor();
+    Optional<ByteString> read_next_line_of_editor();
     size_t m_current_line_for_parsing { 0 };
     int m_editor_line_level { 0 };
 };
diff --git a/Userland/DevTools/SQLStudio/ScriptEditor.cpp b/Userland/DevTools/SQLStudio/ScriptEditor.cpp
index 410866adb81..25d0b112bdd 100644
--- a/Userland/DevTools/SQLStudio/ScriptEditor.cpp
+++ b/Userland/DevTools/SQLStudio/ScriptEditor.cpp
@@ -21,7 +21,7 @@ ScriptEditor::ScriptEditor()
     set_ruler_visible(true);
 }
 
-void ScriptEditor::new_script_with_temp_name(DeprecatedString name)
+void ScriptEditor::new_script_with_temp_name(ByteString name)
 {
     set_name(name);
 }
@@ -37,7 +37,7 @@ ErrorOr<void> ScriptEditor::open_script_from_file(LexicalPath const& file_path)
     return {};
 }
 
-static ErrorOr<void> save_text_to_file(StringView filename, DeprecatedString text)
+static ErrorOr<void> save_text_to_file(StringView filename, ByteString text)
 {
     auto file = TRY(Core::File::open(filename, Core::File::OpenMode::Write));
 
diff --git a/Userland/DevTools/SQLStudio/ScriptEditor.h b/Userland/DevTools/SQLStudio/ScriptEditor.h
index 0de219c0bb5..17e11beb571 100644
--- a/Userland/DevTools/SQLStudio/ScriptEditor.h
+++ b/Userland/DevTools/SQLStudio/ScriptEditor.h
@@ -17,19 +17,19 @@ class ScriptEditor : public GUI::TextEditor {
 public:
     virtual ~ScriptEditor() = default;
 
-    void new_script_with_temp_name(DeprecatedString);
+    void new_script_with_temp_name(ByteString);
     ErrorOr<void> open_script_from_file(LexicalPath const&);
 
     ErrorOr<bool> save();
     ErrorOr<bool> save_as();
     ErrorOr<bool> attempt_to_close();
 
-    DeprecatedString const& path() const { return m_path; }
+    ByteString const& path() const { return m_path; }
 
 private:
     ScriptEditor();
 
-    DeprecatedString m_path;
+    ByteString m_path;
 };
 
 }
diff --git a/Userland/DevTools/UserspaceEmulator/Emulator.cpp b/Userland/DevTools/UserspaceEmulator/Emulator.cpp
index b73082053e3..b6746965a41 100644
--- a/Userland/DevTools/UserspaceEmulator/Emulator.cpp
+++ b/Userland/DevTools/UserspaceEmulator/Emulator.cpp
@@ -42,7 +42,7 @@ Emulator& Emulator::the()
     return *s_the;
 }
 
-Emulator::Emulator(DeprecatedString const& executable_path, Vector<StringView> const& arguments, Vector<DeprecatedString> const& environment)
+Emulator::Emulator(ByteString const& executable_path, Vector<StringView> const& arguments, Vector<ByteString> const& environment)
     : m_executable_path(executable_path)
     , m_arguments(arguments)
     , m_environment(environment)
@@ -70,7 +70,7 @@ Emulator::Emulator(DeprecatedString const& executable_path, Vector<StringView> c
     setup_signal_trampoline();
 }
 
-Vector<ELF::AuxiliaryValue> Emulator::generate_auxiliary_vector(FlatPtr load_base, FlatPtr entry_eip, DeprecatedString const& executable_path, int executable_fd) const
+Vector<ELF::AuxiliaryValue> Emulator::generate_auxiliary_vector(FlatPtr load_base, FlatPtr entry_eip, ByteString const& executable_path, int executable_fd) const
 {
     // FIXME: This is not fully compatible with the auxiliary vector the kernel generates, this is just the bare
     //        minimum to get the loader going.
@@ -227,7 +227,7 @@ int Emulator::exec()
 
     size_t instructions_until_next_profile_dump = profile_instruction_interval();
     if (is_profiling() && m_loader_text_size.has_value())
-        emit_profile_event(profile_stream(), "mmap"sv, DeprecatedString::formatted(R"("ptr": {}, "size": {}, "name": "/usr/lib/Loader.so")", *m_loader_text_base, *m_loader_text_size));
+        emit_profile_event(profile_stream(), "mmap"sv, ByteString::formatted(R"("ptr": {}, "size": {}, "name": "/usr/lib/Loader.so")", *m_loader_text_base, *m_loader_text_size));
 
     while (!m_shutdown) {
         if (m_steps_til_pause) [[likely]] {
@@ -235,7 +235,7 @@ int Emulator::exec()
             auto insn = X86::Instruction::from_stream(*m_cpu, X86::ProcessorMode::Protected);
             // Exec cycle
             if constexpr (trace) {
-                outln("{:p}  \033[33;1m{}\033[0m", m_cpu->base_eip(), insn.to_deprecated_string(m_cpu->base_eip(), symbol_provider));
+                outln("{:p}  \033[33;1m{}\033[0m", m_cpu->base_eip(), insn.to_byte_string(m_cpu->base_eip(), symbol_provider));
             }
 
             (m_cpu->*insn.handler())(insn);
@@ -419,13 +419,13 @@ MmapRegion const* Emulator::load_library_from_address(FlatPtr address)
     if (!region)
         return {};
 
-    DeprecatedString lib_name = region->lib_name();
+    ByteString lib_name = region->lib_name();
     if (lib_name.is_null())
         return {};
 
-    DeprecatedString lib_path = lib_name;
+    ByteString lib_path = lib_name;
     if (FileSystem::looks_like_shared_library(lib_name))
-        lib_path = DeprecatedString::formatted("/usr/lib/{}", lib_path);
+        lib_path = ByteString::formatted("/usr/lib/{}", lib_path);
 
     if (!m_dynamic_library_cache.contains(lib_path)) {
         auto file_or_error = Core::MappedFile::map(lib_path);
@@ -463,7 +463,7 @@ Optional<Emulator::SymbolInfo> Emulator::symbol_at(FlatPtr address)
     VERIFY(first_region);
     auto lib_path = lib_name;
     if (FileSystem::looks_like_shared_library(lib_name)) {
-        lib_path = DeprecatedString::formatted("/usr/lib/{}", lib_name);
+        lib_path = ByteString::formatted("/usr/lib/{}", lib_name);
     }
 
     auto it = m_dynamic_library_cache.find(lib_path);
@@ -474,18 +474,18 @@ Optional<Emulator::SymbolInfo> Emulator::symbol_at(FlatPtr address)
     return { { lib_name, symbol, source_position } };
 }
 
-DeprecatedString Emulator::create_backtrace_line(FlatPtr address)
+ByteString Emulator::create_backtrace_line(FlatPtr address)
 {
     auto maybe_symbol = symbol_at(address);
     if (!maybe_symbol.has_value()) {
-        return DeprecatedString::formatted("=={}==    {:p}", getpid(), address);
+        return ByteString::formatted("=={}==    {:p}", getpid(), address);
     }
     if (!maybe_symbol->source_position.has_value()) {
-        return DeprecatedString::formatted("=={}==    {:p}  [{}]: {}", getpid(), address, maybe_symbol->lib_name, maybe_symbol->symbol);
+        return ByteString::formatted("=={}==    {:p}  [{}]: {}", getpid(), address, maybe_symbol->lib_name, maybe_symbol->symbol);
     }
 
     auto const& source_position = maybe_symbol->source_position.value();
-    return DeprecatedString::formatted("=={}==    {:p}  [{}]: {} (\e[34;1m{}\e[0m:{})", getpid(), address, maybe_symbol->lib_name, maybe_symbol->symbol, LexicalPath::basename(source_position.file_path), source_position.line_number);
+    return ByteString::formatted("=={}==    {:p}  [{}]: {} (\e[34;1m{}\e[0m:{})", getpid(), address, maybe_symbol->lib_name, maybe_symbol->symbol, LexicalPath::basename(source_position.file_path), source_position.line_number);
 }
 
 void Emulator::dump_backtrace(Vector<FlatPtr> const& backtrace)
@@ -513,7 +513,7 @@ void Emulator::emit_profile_sample(Stream& output)
     output.write_until_depleted(builder.string_view().bytes()).release_value_but_fixme_should_propagate_errors();
 }
 
-void Emulator::emit_profile_event(Stream& output, StringView event_name, DeprecatedString const& contents)
+void Emulator::emit_profile_event(Stream& output, StringView event_name, ByteString const& contents)
 {
     StringBuilder builder;
     timeval tv {};
@@ -523,13 +523,13 @@ void Emulator::emit_profile_event(Stream& output, StringView event_name, Depreca
     output.write_until_depleted(builder.string_view().bytes()).release_value_but_fixme_should_propagate_errors();
 }
 
-DeprecatedString Emulator::create_instruction_line(FlatPtr address, X86::Instruction const& insn)
+ByteString Emulator::create_instruction_line(FlatPtr address, X86::Instruction const& insn)
 {
     auto symbol = symbol_at(address);
     if (!symbol.has_value() || !symbol->source_position.has_value())
-        return DeprecatedString::formatted("{:p}: {}", address, insn.to_deprecated_string(address));
+        return ByteString::formatted("{:p}: {}", address, insn.to_byte_string(address));
 
-    return DeprecatedString::formatted("{:p}: {} \e[34;1m{}\e[0m:{}", address, insn.to_deprecated_string(address), LexicalPath::basename(symbol->source_position->file_path), symbol->source_position.value().line_number);
+    return ByteString::formatted("{:p}: {} \e[34;1m{}\e[0m:{}", address, insn.to_byte_string(address), LexicalPath::basename(symbol->source_position->file_path), symbol->source_position.value().line_number);
 }
 
 static void emulator_signal_handler(int signum, siginfo_t* signal_info, void* context)
diff --git a/Userland/DevTools/UserspaceEmulator/Emulator.h b/Userland/DevTools/UserspaceEmulator/Emulator.h
index 20424fa3a3c..f295508a4a2 100644
--- a/Userland/DevTools/UserspaceEmulator/Emulator.h
+++ b/Userland/DevTools/UserspaceEmulator/Emulator.h
@@ -30,9 +30,9 @@ class Emulator {
 public:
     static Emulator& the();
 
-    Emulator(DeprecatedString const& executable_path, Vector<StringView> const& arguments, Vector<DeprecatedString> const& environment);
+    Emulator(ByteString const& executable_path, Vector<StringView> const& arguments, Vector<ByteString> const& environment);
 
-    void set_profiling_details(bool should_dump_profile, size_t instruction_interval, Stream* profile_stream, Vector<NonnullOwnPtr<DeprecatedString>>* profiler_strings, Vector<int>* profiler_string_id_map)
+    void set_profiling_details(bool should_dump_profile, size_t instruction_interval, Stream* profile_stream, Vector<NonnullOwnPtr<ByteString>>* profiler_strings, Vector<int>* profiler_string_id_map)
     {
         m_is_profiling = should_dump_profile;
         m_profile_instruction_interval = instruction_interval;
@@ -47,7 +47,7 @@ public:
     }
 
     Stream& profile_stream() { return *m_profile_stream; }
-    Vector<NonnullOwnPtr<DeprecatedString>>& profiler_strings() { return *m_profiler_strings; }
+    Vector<NonnullOwnPtr<ByteString>>& profiler_strings() { return *m_profiler_strings; }
     Vector<int>& profiler_string_id_map() { return *m_profiler_string_id_map; }
 
     bool is_profiling() const { return m_is_profiling; }
@@ -113,8 +113,8 @@ public:
     }
 
     struct SymbolInfo {
-        DeprecatedString lib_name;
-        DeprecatedString symbol;
+        ByteString lib_name;
+        ByteString symbol;
         Optional<Debug::DebugInfo::SourcePosition> source_position;
     };
 
@@ -123,9 +123,9 @@ public:
     void dump_regions() const;
 
 private:
-    const DeprecatedString m_executable_path;
+    const ByteString m_executable_path;
     Vector<StringView> const m_arguments;
-    Vector<DeprecatedString> const m_environment;
+    Vector<ByteString> const m_environment;
 
     SoftMMU m_mmu;
     NonnullOwnPtr<SoftCPU> m_cpu;
@@ -133,14 +133,14 @@ private:
     OwnPtr<MallocTracer> m_malloc_tracer;
 
     void setup_stack(Vector<ELF::AuxiliaryValue>);
-    Vector<ELF::AuxiliaryValue> generate_auxiliary_vector(FlatPtr load_base, FlatPtr entry_eip, DeprecatedString const& executable_path, int executable_fd) const;
+    Vector<ELF::AuxiliaryValue> generate_auxiliary_vector(FlatPtr load_base, FlatPtr entry_eip, ByteString const& executable_path, int executable_fd) const;
     void register_signal_handlers();
     void setup_signal_trampoline();
 
     void send_signal(int);
 
     void emit_profile_sample(Stream&);
-    void emit_profile_event(Stream&, StringView event_name, DeprecatedString const& contents);
+    void emit_profile_event(Stream&, StringView event_name, ByteString const& contents);
 
     int virt$accept4(FlatPtr);
     u32 virt$allocate_tls(FlatPtr, size_t);
@@ -254,8 +254,8 @@ private:
     MmapRegion const* find_text_region(FlatPtr address);
     MmapRegion const* load_library_from_address(FlatPtr address);
     MmapRegion const* first_region_for_object(StringView name);
-    DeprecatedString create_backtrace_line(FlatPtr address);
-    DeprecatedString create_instruction_line(FlatPtr address, X86::Instruction const& insn);
+    ByteString create_backtrace_line(FlatPtr address);
+    ByteString create_instruction_line(FlatPtr address, X86::Instruction const& insn);
 
     bool m_shutdown { false };
     int m_exit_status { 0 };
@@ -290,13 +290,13 @@ private:
         NonnullOwnPtr<ELF::Image> image;
     };
 
-    HashMap<DeprecatedString, CachedELF> m_dynamic_library_cache;
+    HashMap<ByteString, CachedELF> m_dynamic_library_cache;
 
     RangeAllocator m_range_allocator;
 
     Stream* m_profile_stream { nullptr };
     Vector<int>* m_profiler_string_id_map { nullptr };
-    Vector<NonnullOwnPtr<DeprecatedString>>* m_profiler_strings { nullptr };
+    Vector<NonnullOwnPtr<ByteString>>* m_profiler_strings { nullptr };
 
     bool m_is_profiling { false };
     size_t m_profile_instruction_interval { 0 };
diff --git a/Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp b/Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp
index 07cf3abc7ee..6658d75b490 100644
--- a/Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp
+++ b/Userland/DevTools/UserspaceEmulator/Emulator_syscalls.cpp
@@ -292,7 +292,7 @@ FlatPtr Emulator::virt$perf_event(int event, FlatPtr arg1, FlatPtr arg2)
     if (event == PERF_EVENT_SIGNPOST) {
         if (is_profiling()) {
             if (profiler_string_id_map().size() > arg1)
-                emit_profile_event(profile_stream(), "signpost"sv, DeprecatedString::formatted("\"arg1\": {}, \"arg2\": {}", arg1, arg2));
+                emit_profile_event(profile_stream(), "signpost"sv, ByteString::formatted("\"arg1\": {}, \"arg2\": {}", arg1, arg2));
             syscall(SC_perf_event, PERF_EVENT_SIGNPOST, profiler_string_id_map().at(arg1), arg2);
         } else {
             syscall(SC_perf_event, PERF_EVENT_SIGNPOST, arg1, arg2);
@@ -311,7 +311,7 @@ FlatPtr Emulator::virt$perf_register_string(FlatPtr string, size_t size)
     auto ret = (int)syscall(SC_perf_register_string, buffer, size + 4);
 
     if (ret >= 0 && is_profiling()) {
-        profiler_strings().append(make<DeprecatedString>(StringView { buffer + 4, size }));
+        profiler_strings().append(make<ByteString>(StringView { buffer + 4, size }));
         profiler_string_id_map().append(ret);
         ret = profiler_string_id_map().size() - 1;
     }
@@ -564,7 +564,7 @@ int Emulator::virt$set_mmap_name(FlatPtr params_addr)
     auto* region = mmu().find_region({ 0x23, (FlatPtr)params.addr });
     if (!region || !is<MmapRegion>(*region))
         return -EINVAL;
-    static_cast<MmapRegion&>(*region).set_name(DeprecatedString::copy(name));
+    static_cast<MmapRegion&>(*region).set_name(ByteString::copy(name));
     return 0;
 }
 
@@ -802,7 +802,7 @@ static void round_to_page_size(FlatPtr& address, size_t& size)
 u32 Emulator::virt$munmap(FlatPtr address, size_t size)
 {
     if (is_profiling())
-        emit_profile_event(profile_stream(), "munmap"sv, DeprecatedString::formatted("\"ptr\": {}, \"size\": {}", address, size));
+        emit_profile_event(profile_stream(), "munmap"sv, ByteString::formatted("\"ptr\": {}, \"size\": {}", address, size));
     round_to_page_size(address, size);
     Vector<Region*, 4> marked_for_deletion;
     bool has_non_mmap_region = false;
@@ -861,7 +861,7 @@ u32 Emulator::virt$mmap(u32 params_addr)
     final_address = result.value().base().get();
     auto final_size = result.value().size();
 
-    DeprecatedString name_str;
+    ByteString name_str;
     if (params.name.characters) {
         auto buffer_result = ByteBuffer::create_uninitialized(params.name.length);
         if (buffer_result.is_error())
@@ -872,7 +872,7 @@ u32 Emulator::virt$mmap(u32 params_addr)
     }
 
     if (is_profiling())
-        emit_profile_event(profile_stream(), "mmap"sv, DeprecatedString::formatted(R"("ptr": {}, "size": {}, "name": "{}")", final_address, final_size, name_str));
+        emit_profile_event(profile_stream(), "mmap"sv, ByteString::formatted(R"("ptr": {}, "size": {}, "name": "{}")", final_address, final_size, name_str));
 
     if (params.flags & MAP_ANONYMOUS) {
         mmu().add_region(MmapRegion::create_anonymous(final_address, final_size, params.prot, move(name_str)));
@@ -1216,15 +1216,15 @@ int Emulator::virt$execve(FlatPtr params_addr)
     Syscall::SC_execve_params params;
     mmu().copy_from_vm(&params, params_addr, sizeof(params));
 
-    auto path = DeprecatedString::copy(mmu().copy_buffer_from_vm((FlatPtr)params.path.characters, params.path.length));
-    Vector<DeprecatedString> arguments;
-    Vector<DeprecatedString> environment;
+    auto path = ByteString::copy(mmu().copy_buffer_from_vm((FlatPtr)params.path.characters, params.path.length));
+    Vector<ByteString> arguments;
+    Vector<ByteString> environment;
 
     auto copy_string_list = [this](auto& output_vector, auto& string_list) {
         for (size_t i = 0; i < string_list.length; ++i) {
             Syscall::StringArgument string;
             mmu().copy_from_vm(&string, (FlatPtr)&string_list.strings[i], sizeof(string));
-            output_vector.append(DeprecatedString::copy(mmu().copy_buffer_from_vm((FlatPtr)string.characters, string.length)));
+            output_vector.append(ByteString::copy(mmu().copy_buffer_from_vm((FlatPtr)string.characters, string.length)));
         }
     };
 
@@ -1270,7 +1270,7 @@ int Emulator::virt$stat(FlatPtr params_addr)
     Syscall::SC_stat_params params;
     mmu().copy_from_vm(&params, params_addr, sizeof(params));
 
-    auto path = DeprecatedString::copy(mmu().copy_buffer_from_vm((FlatPtr)params.path.characters, params.path.length));
+    auto path = ByteString::copy(mmu().copy_buffer_from_vm((FlatPtr)params.path.characters, params.path.length));
     struct stat host_statbuf;
     int rc;
     if (params.follow_symlinks)
diff --git a/Userland/DevTools/UserspaceEmulator/MmapRegion.cpp b/Userland/DevTools/UserspaceEmulator/MmapRegion.cpp
index 981b2977e9b..9373862589a 100644
--- a/Userland/DevTools/UserspaceEmulator/MmapRegion.cpp
+++ b/Userland/DevTools/UserspaceEmulator/MmapRegion.cpp
@@ -26,20 +26,20 @@ static void free_pages(void* ptr, size_t bytes)
     VERIFY(rc == 0);
 }
 
-NonnullOwnPtr<MmapRegion> MmapRegion::create_anonymous(u32 base, u32 size, u32 prot, DeprecatedString name)
+NonnullOwnPtr<MmapRegion> MmapRegion::create_anonymous(u32 base, u32 size, u32 prot, ByteString name)
 {
-    auto* data = (u8*)mmap_initialized(size, 0, DeprecatedString::formatted("(UE) {}", name).characters());
+    auto* data = (u8*)mmap_initialized(size, 0, ByteString::formatted("(UE) {}", name).characters());
     auto* shadow_data = (u8*)mmap_initialized(size, 1, "MmapRegion ShadowData");
     auto region = adopt_own(*new MmapRegion(base, size, prot, data, shadow_data));
     region->m_name = move(name);
     return region;
 }
 
-NonnullOwnPtr<MmapRegion> MmapRegion::create_file_backed(u32 base, u32 size, u32 prot, int flags, int fd, off_t offset, DeprecatedString name)
+NonnullOwnPtr<MmapRegion> MmapRegion::create_file_backed(u32 base, u32 size, u32 prot, int flags, int fd, off_t offset, ByteString name)
 {
     // Since we put the memory to an arbitrary location, do not pass MAP_FIXED and MAP_FIXED_NOREPLACE to the Kernel.
     auto real_flags = flags & ~(MAP_FIXED | MAP_FIXED_NOREPLACE);
-    auto* data = (u8*)mmap_with_name(nullptr, size, prot, real_flags, fd, offset, name.is_empty() ? nullptr : DeprecatedString::formatted("(UE) {}", name).characters());
+    auto* data = (u8*)mmap_with_name(nullptr, size, prot, real_flags, fd, offset, name.is_empty() ? nullptr : ByteString::formatted("(UE) {}", name).characters());
     VERIFY(data != MAP_FAILED);
     auto* shadow_data = (u8*)mmap_initialized(size, 1, "MmapRegion ShadowData");
     auto region = adopt_own(*new MmapRegion(base, size, prot, data, shadow_data));
@@ -318,10 +318,10 @@ void MmapRegion::set_prot(int prot)
     }
 }
 
-void MmapRegion::set_name(DeprecatedString name)
+void MmapRegion::set_name(ByteString name)
 {
     m_name = move(name);
-    set_mmap_name(range().base().as_ptr(), range().size(), DeprecatedString::formatted("(UE) {}", m_name).characters());
+    set_mmap_name(range().base().as_ptr(), range().size(), ByteString::formatted("(UE) {}", m_name).characters());
 }
 
 }
diff --git a/Userland/DevTools/UserspaceEmulator/MmapRegion.h b/Userland/DevTools/UserspaceEmulator/MmapRegion.h
index a4f37f45253..e4593ea04d8 100644
--- a/Userland/DevTools/UserspaceEmulator/MmapRegion.h
+++ b/Userland/DevTools/UserspaceEmulator/MmapRegion.h
@@ -16,8 +16,8 @@ class MallocTracer;
 
 class MmapRegion final : public Region {
 public:
-    static NonnullOwnPtr<MmapRegion> create_anonymous(u32 base, u32 size, u32 prot, DeprecatedString name);
-    static NonnullOwnPtr<MmapRegion> create_file_backed(u32 base, u32 size, u32 prot, int flags, int fd, off_t offset, DeprecatedString name);
+    static NonnullOwnPtr<MmapRegion> create_anonymous(u32 base, u32 size, u32 prot, ByteString name);
+    static NonnullOwnPtr<MmapRegion> create_file_backed(u32 base, u32 size, u32 prot, int flags, int fd, off_t offset, ByteString name);
     virtual ~MmapRegion() override;
 
     virtual ValueWithShadow<u8> read8(u32 offset) override;
@@ -51,8 +51,8 @@ public:
     MallocRegionMetadata* malloc_metadata() { return m_malloc_metadata; }
     void set_malloc_metadata(Badge<MallocTracer>, NonnullOwnPtr<MallocRegionMetadata> metadata) { m_malloc_metadata = move(metadata); }
 
-    DeprecatedString const& name() const { return m_name; }
-    DeprecatedString lib_name() const
+    ByteString const& name() const { return m_name; }
+    ByteString lib_name() const
     {
         if (m_name.contains("Loader.so"sv))
             return "Loader.so";
@@ -61,7 +61,7 @@ public:
             return {};
         return m_name.substring(0, *maybe_separator);
     }
-    void set_name(DeprecatedString name);
+    void set_name(ByteString name);
 
 private:
     MmapRegion(u32 base, u32 size, int prot, u8* data, u8* shadow_data);
@@ -72,7 +72,7 @@ private:
     bool m_malloc { false };
 
     OwnPtr<MallocRegionMetadata> m_malloc_metadata;
-    DeprecatedString m_name;
+    ByteString m_name;
 };
 
 template<>
diff --git a/Userland/DevTools/UserspaceEmulator/SoftFPU.h b/Userland/DevTools/UserspaceEmulator/SoftFPU.h
index 5b61fcb9f3e..2abdcbaa93b 100644
--- a/Userland/DevTools/UserspaceEmulator/SoftFPU.h
+++ b/Userland/DevTools/UserspaceEmulator/SoftFPU.h
@@ -114,7 +114,7 @@ private:
         }
     }
 
-    DeprecatedString fpu_exception_string(FPU_Exception ex)
+    ByteString fpu_exception_string(FPU_Exception ex)
     {
         switch (ex) {
         case FPU_Exception::StackFault:
diff --git a/Userland/DevTools/UserspaceEmulator/main.cpp b/Userland/DevTools/UserspaceEmulator/main.cpp
index 3f46eb6f1a7..25993a7d0cc 100644
--- a/Userland/DevTools/UserspaceEmulator/main.cpp
+++ b/Userland/DevTools/UserspaceEmulator/main.cpp
@@ -23,7 +23,7 @@ int main(int argc, char** argv, char** env)
 {
     Vector<StringView> arguments;
     bool pause_on_startup { false };
-    DeprecatedString profile_dump_path;
+    ByteString profile_dump_path;
     bool enable_roi_mode { false };
     bool dump_profile { false };
     unsigned profile_instruction_interval { 0 };
@@ -51,13 +51,13 @@ int main(int argc, char** argv, char** env)
         reportln("Cannot find executable for '{}'."sv, arguments[0]);
         return 1;
     }
-    auto executable_path = executable_path_or_error.release_value().to_deprecated_string();
+    auto executable_path = executable_path_or_error.release_value().to_byte_string();
 
     if (dump_profile && profile_dump_path.is_empty())
-        profile_dump_path = DeprecatedString::formatted("{}.{}.profile", LexicalPath(executable_path).basename(), getpid());
+        profile_dump_path = ByteString::formatted("{}.{}.profile", LexicalPath(executable_path).basename(), getpid());
 
     OwnPtr<Stream> profile_stream;
-    OwnPtr<Vector<NonnullOwnPtr<DeprecatedString>>> profile_strings;
+    OwnPtr<Vector<NonnullOwnPtr<ByteString>>> profile_strings;
     OwnPtr<Vector<int>> profile_string_id_map;
 
     if (dump_profile) {
@@ -67,21 +67,21 @@ int main(int argc, char** argv, char** env)
             return 1;
         }
         profile_stream = profile_stream_or_error.release_value();
-        profile_strings = make<Vector<NonnullOwnPtr<DeprecatedString>>>();
+        profile_strings = make<Vector<NonnullOwnPtr<ByteString>>>();
         profile_string_id_map = make<Vector<int>>();
 
         profile_stream->write_until_depleted(R"({"events":[)"sv.bytes()).release_value_but_fixme_should_propagate_errors();
         timeval tv {};
         gettimeofday(&tv, nullptr);
         profile_stream->write_until_depleted(
-                          DeprecatedString::formatted(
+                          ByteString::formatted(
                               R"~({{"type": "process_create", "parent_pid": 1, "executable": "{}", "pid": {}, "tid": {}, "timestamp": {}, "lost_samples": 0, "stack": []}})~",
                               executable_path, getpid(), gettid(), tv.tv_sec * 1000 + tv.tv_usec / 1000)
                               .bytes())
             .release_value_but_fixme_should_propagate_errors();
     }
 
-    Vector<DeprecatedString> environment;
+    Vector<ByteString> environment;
     for (int i = 0; env[i]; ++i) {
         environment.append(env[i]);
     }
@@ -112,8 +112,8 @@ int main(int argc, char** argv, char** env)
         emulator.profile_stream().write_until_depleted("], \"strings\": ["sv.bytes()).release_value_but_fixme_should_propagate_errors();
         if (emulator.profiler_strings().size()) {
             for (size_t i = 0; i < emulator.profiler_strings().size() - 1; ++i)
-                emulator.profile_stream().write_until_depleted(DeprecatedString::formatted("\"{}\", ", emulator.profiler_strings().at(i)).bytes()).release_value_but_fixme_should_propagate_errors();
-            emulator.profile_stream().write_until_depleted(DeprecatedString::formatted("\"{}\"", emulator.profiler_strings().last()).bytes()).release_value_but_fixme_should_propagate_errors();
+                emulator.profile_stream().write_until_depleted(ByteString::formatted("\"{}\", ", emulator.profiler_strings().at(i)).bytes()).release_value_but_fixme_should_propagate_errors();
+            emulator.profile_stream().write_until_depleted(ByteString::formatted("\"{}\"", emulator.profiler_strings().last()).bytes()).release_value_but_fixme_should_propagate_errors();
         }
         emulator.profile_stream().write_until_depleted("]}"sv.bytes()).release_value_but_fixme_should_propagate_errors();
     }
diff --git a/Userland/DynamicLoader/main.cpp b/Userland/DynamicLoader/main.cpp
index 3d0d1a80eda..efaf3eb2111 100644
--- a/Userland/DynamicLoader/main.cpp
+++ b/Userland/DynamicLoader/main.cpp
@@ -122,7 +122,7 @@ void _entry(int argc, char** argv, char** envp)
     init_libc();
 
     int main_program_fd = -1;
-    DeprecatedString main_program_path;
+    ByteString main_program_path;
     bool is_secure = false;
     for (; auxvp->a_type != AT_NULL; ++auxvp) {
         if (auxvp->a_type == ELF::AuxiliaryValue::ExecFileDescriptor) {
diff --git a/Userland/Games/Chess/ChessWidget.cpp b/Userland/Games/Chess/ChessWidget.cpp
index 35a059c1d22..faa676f5c95 100644
--- a/Userland/Games/Chess/ChessWidget.cpp
+++ b/Userland/Games/Chess/ChessWidget.cpp
@@ -638,11 +638,11 @@ ErrorOr<void> ChessWidget::export_pgn(Core::File& file) const
     // Tag Pair Section
     TRY(file.write_until_depleted("[Event \"Casual Game\"]\n"sv.bytes()));
     TRY(file.write_until_depleted("[Site \"SerenityOS Chess\"]\n"sv.bytes()));
-    TRY(file.write_formatted("[Date \"{}\"]\n", Core::DateTime::now().to_deprecated_string("%Y.%m.%d"sv)));
+    TRY(file.write_formatted("[Date \"{}\"]\n", Core::DateTime::now().to_byte_string("%Y.%m.%d"sv)));
     TRY(file.write_until_depleted("[Round \"1\"]\n"sv.bytes()));
 
     auto current_user = TRY(Core::Account::self(Core::Account::Read::PasswdOnly));
-    auto const username = TRY(String::from_deprecated_string(current_user.username()));
+    auto const username = TRY(String::from_byte_string(current_user.username()));
 
     auto const player1 = (!username.is_empty() ? username : "?"sv);
     auto const player2 = (!m_engine.is_null() ? "SerenityOS ChessEngine"sv : "?"sv);
diff --git a/Userland/Games/Hearts/Game.cpp b/Userland/Games/Hearts/Game.cpp
index 685d0a9cdc7..729620455f2 100644
--- a/Userland/Games/Hearts/Game.cpp
+++ b/Userland/Games/Hearts/Game.cpp
@@ -147,7 +147,7 @@ void Game::show_score_card(bool game_over)
     title_builder.append("Score Card"sv);
     if (game_over)
         title_builder.append(" - Game Over"sv);
-    score_dialog->set_title(title_builder.to_deprecated_string());
+    score_dialog->set_title(title_builder.to_byte_string());
 
     RefPtr<Core::Timer> close_timer;
     if (!m_players[0].is_human) {
@@ -160,7 +160,7 @@ void Game::show_score_card(bool game_over)
     score_dialog->exec();
 }
 
-void Game::setup(DeprecatedString player_name, int hand_number)
+void Game::setup(ByteString player_name, int hand_number)
 {
     m_players[0].name = move(player_name);
 
@@ -619,7 +619,7 @@ void Game::play_card(Player& player, size_t card_index)
         0);
 }
 
-bool Game::is_valid_play(Player& player, Card& card, DeprecatedString* explanation) const
+bool Game::is_valid_play(Player& player, Card& card, ByteString* explanation) const
 {
     // First card must be 2 of Clubs.
     if (m_trick_number == 0 && m_trick.is_empty()) {
@@ -692,7 +692,7 @@ void Game::card_clicked_during_passing(size_t, Card& card)
 
 void Game::card_clicked_during_play(size_t card_index, Card& card)
 {
-    DeprecatedString explanation;
+    ByteString explanation;
     if (!is_valid_play(m_players[0], card, &explanation)) {
         if (m_inverted_card)
             m_inverted_card->set_inverted(false);
diff --git a/Userland/Games/Hearts/Game.h b/Userland/Games/Hearts/Game.h
index 85122969196..605f231d055 100644
--- a/Userland/Games/Hearts/Game.h
+++ b/Userland/Games/Hearts/Game.h
@@ -26,7 +26,7 @@ public:
 
     virtual ~Game() override = default;
 
-    void setup(DeprecatedString player_name, int hand_number = 0);
+    void setup(ByteString player_name, int hand_number = 0);
 
     Function<void(String const&)> on_status_change;
 
@@ -41,7 +41,7 @@ private:
 
     void play_card(Player& player, size_t card_index);
     bool are_hearts_broken() const;
-    bool is_valid_play(Player& player, Card& card, DeprecatedString* explanation = nullptr) const;
+    bool is_valid_play(Player& player, Card& card, ByteString* explanation = nullptr) const;
     void let_player_play_card();
     void continue_game_after_delay(int interval_ms = 750);
     void advance_game();
diff --git a/Userland/Games/Hearts/Player.h b/Userland/Games/Hearts/Player.h
index 2a7b576d00d..d401eb7c4af 100644
--- a/Userland/Games/Hearts/Player.h
+++ b/Userland/Games/Hearts/Player.h
@@ -55,7 +55,7 @@ public:
     Gfx::IntRect name_position;
     Gfx::TextAlignment name_alignment;
     Gfx::IntPoint taken_cards_target;
-    DeprecatedString name;
+    ByteString name;
     bool is_human { false };
 };
 
diff --git a/Userland/Games/Hearts/ScoreCard.cpp b/Userland/Games/Hearts/ScoreCard.cpp
index fd33ece4745..41077681f9c 100644
--- a/Userland/Games/Hearts/ScoreCard.cpp
+++ b/Userland/Games/Hearts/ScoreCard.cpp
@@ -70,7 +70,7 @@ void ScoreCard::paint_event(GUI::PaintEvent& event)
             text_color);
         for (int score_index = 0; score_index < (int)player.scores.size(); score_index++) {
             auto text_rect = cell_rect(player_index, 1 + score_index);
-            auto score_text = DeprecatedString::formatted("{}", player.scores[score_index]);
+            auto score_text = ByteString::formatted("{}", player.scores[score_index]);
             auto score_text_width = font.width_rounded_up(score_text);
             if (score_index != (int)player.scores.size() - 1) {
                 painter.draw_line(
diff --git a/Userland/Games/Hearts/SettingsDialog.cpp b/Userland/Games/Hearts/SettingsDialog.cpp
index cbf85c8903c..3371f5e5827 100644
--- a/Userland/Games/Hearts/SettingsDialog.cpp
+++ b/Userland/Games/Hearts/SettingsDialog.cpp
@@ -10,7 +10,7 @@
 #include <LibGUI/Label.h>
 #include <LibGUI/TextBox.h>
 
-SettingsDialog::SettingsDialog(GUI::Window* parent, DeprecatedString player_name)
+SettingsDialog::SettingsDialog(GUI::Window* parent, ByteString player_name)
     : GUI::Dialog(parent)
     , m_player_name(move(player_name))
 {
diff --git a/Userland/Games/Hearts/SettingsDialog.h b/Userland/Games/Hearts/SettingsDialog.h
index 1933537960b..d85407c82d9 100644
--- a/Userland/Games/Hearts/SettingsDialog.h
+++ b/Userland/Games/Hearts/SettingsDialog.h
@@ -12,10 +12,10 @@
 class SettingsDialog : public GUI::Dialog {
     C_OBJECT(SettingsDialog)
 public:
-    DeprecatedString const& player_name() const { return m_player_name; }
+    ByteString const& player_name() const { return m_player_name; }
 
 private:
-    SettingsDialog(GUI::Window* parent, DeprecatedString player_name);
+    SettingsDialog(GUI::Window* parent, ByteString player_name);
 
-    DeprecatedString m_player_name { "Gunnar" };
+    ByteString m_player_name { "Gunnar" };
 };
diff --git a/Userland/Games/Hearts/main.cpp b/Userland/Games/Hearts/main.cpp
index 076d869b46a..94964170ba0 100644
--- a/Userland/Games/Hearts/main.cpp
+++ b/Userland/Games/Hearts/main.cpp
@@ -59,7 +59,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto& statusbar = *widget->find_descendant_of_type_named<GUI::Statusbar>("statusbar");
     statusbar.set_text(0, "Score: 0"_string);
 
-    DeprecatedString player_name = Config::read_string("Hearts"sv, ""sv, "player_name"sv, "Gunnar"sv);
+    ByteString player_name = Config::read_string("Hearts"sv, ""sv, "player_name"sv, "Gunnar"sv);
 
     game.on_status_change = [&](String const& status) {
         statusbar.set_override_text(status);
diff --git a/Userland/Games/MasterWord/WordGame.cpp b/Userland/Games/MasterWord/WordGame.cpp
index aba0f46aec7..f1897d092b2 100644
--- a/Userland/Games/MasterWord/WordGame.cpp
+++ b/Userland/Games/MasterWord/WordGame.cpp
@@ -40,7 +40,7 @@ void WordGame::reset()
     if (maybe_word.has_value())
         m_current_word = maybe_word.value();
     else {
-        GUI::MessageBox::show(window(), DeprecatedString::formatted("Could not get a random {} letter word. Defaulting to 5.", m_num_letters), "MasterWord"sv);
+        GUI::MessageBox::show(window(), ByteString::formatted("Could not get a random {} letter word. Defaulting to 5.", m_num_letters), "MasterWord"sv);
         if (m_num_letters != 5) {
             m_num_letters = 5;
             reset();
@@ -53,7 +53,7 @@ void WordGame::reset()
 
 void WordGame::pick_font()
 {
-    DeprecatedString best_font_name;
+    ByteString best_font_name;
     auto best_font_size = -1;
     auto& font_database = Gfx::FontDatabase::the();
     font_database.for_each_font([&](Gfx::Font const& font) {
@@ -61,7 +61,7 @@ void WordGame::pick_font()
             return;
         auto size = font.pixel_size_rounded_up();
         if (size * 2 <= m_letter_height && size > best_font_size) {
-            best_font_name = font.qualified_name().to_deprecated_string();
+            best_font_name = font.qualified_name().to_byte_string();
             best_font_size = size;
         }
     });
@@ -80,7 +80,7 @@ void WordGame::keydown_event(GUI::KeyEvent& event)
 {
     // If we can still add a letter and the key was alpha
     if (m_current_guess.length() < m_num_letters && is_ascii_alpha(event.code_point())) {
-        m_current_guess = DeprecatedString::formatted("{}{}", m_current_guess, event.text().to_uppercase());
+        m_current_guess = ByteString::formatted("{}{}", m_current_guess, event.text().to_uppercase());
         m_last_word_invalid = false;
     }
     // If backspace pressed and already have some letters entered
@@ -107,7 +107,7 @@ void WordGame::keydown_event(GUI::KeyEvent& event)
                 GUI::MessageBox::show(window(), "You win!"sv, "MasterWord"sv);
                 reset();
             } else if (m_guesses.size() == m_max_guesses) {
-                GUI::MessageBox::show(window(), DeprecatedString::formatted("You lose!\nThe word was {}", m_current_word), "MasterWord"sv);
+                GUI::MessageBox::show(window(), ByteString::formatted("You lose!\nThe word was {}", m_current_word), "MasterWord"sv);
                 reset();
             }
         }
@@ -194,7 +194,7 @@ void WordGame::read_words()
     }
 }
 
-Optional<DeprecatedString> WordGame::random_word(size_t length)
+Optional<ByteString> WordGame::random_word(size_t length)
 {
     auto words_for_length = m_words.get(length);
     if (words_for_length.has_value()) {
diff --git a/Userland/Games/MasterWord/WordGame.h b/Userland/Games/MasterWord/WordGame.h
index 4b7fa90eb8a..ebda18b2649 100644
--- a/Userland/Games/MasterWord/WordGame.h
+++ b/Userland/Games/MasterWord/WordGame.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/RefPtr.h>
 #include <AK/StringView.h>
@@ -30,7 +30,7 @@ public:
     void set_max_guesses(size_t max_guesses);
     Gfx::IntSize game_size() const;
 
-    Optional<DeprecatedString> random_word(size_t length);
+    Optional<ByteString> random_word(size_t length);
     size_t shortest_word();
     size_t longest_word();
     bool is_checking_guesses() const;
@@ -77,15 +77,15 @@ private:
     };
 
     struct Guess {
-        AK::DeprecatedString text;
+        AK::ByteString text;
         AK::Vector<LetterState> letter_states;
     };
 
     AK::Vector<Guess> m_guesses;
-    AK::DeprecatedString m_current_guess;
-    AK::DeprecatedString m_current_word;
+    AK::ByteString m_current_guess;
+    AK::ByteString m_current_word;
 
-    HashMap<size_t, AK::Vector<DeprecatedString>> m_words;
+    HashMap<size_t, AK::Vector<ByteString>> m_words;
 
     NonnullRefPtr<Core::Timer> m_clear_message_timer;
 };
diff --git a/Userland/Games/Minesweeper/Field.cpp b/Userland/Games/Minesweeper/Field.cpp
index e7ddc75a32c..516b510136b 100644
--- a/Userland/Games/Minesweeper/Field.cpp
+++ b/Userland/Games/Minesweeper/Field.cpp
@@ -120,7 +120,7 @@ ErrorOr<NonnullRefPtr<Field>> Field::create(GUI::Label& flag_label, GUI::Label&
     field->m_good_face_bitmap = TRY(Gfx::Bitmap::load_from_file("/res/graphics/minesweeper/face-good.png"sv));
     field->m_bad_face_bitmap = TRY(Gfx::Bitmap::load_from_file("/res/graphics/minesweeper/face-bad.png"sv));
     for (int i = 0; i < 8; ++i)
-        field->m_number_bitmap[i] = TRY(Gfx::Bitmap::load_from_file(DeprecatedString::formatted("/res/graphics/minesweeper/{}.png", i + 1)));
+        field->m_number_bitmap[i] = TRY(Gfx::Bitmap::load_from_file(ByteString::formatted("/res/graphics/minesweeper/{}.png", i + 1)));
     field->initialize();
     return field;
 }
@@ -138,7 +138,7 @@ void Field::initialize()
     m_timer = Core::Timer::create_repeating(
         1000, [this] {
             ++m_time_elapsed;
-            m_time_label.set_text(String::from_deprecated_string(human_readable_digital_time(m_time_elapsed)).release_value_but_fixme_should_propagate_errors());
+            m_time_label.set_text(String::from_byte_string(human_readable_digital_time(m_time_elapsed)).release_value_but_fixme_should_propagate_errors());
         },
         this)
                   .release_value_but_fixme_should_propagate_errors();
diff --git a/Userland/Games/Snake/Game.cpp b/Userland/Games/Snake/Game.cpp
index dc8e945aedd..25c250c3a47 100644
--- a/Userland/Games/Snake/Game.cpp
+++ b/Userland/Games/Snake/Game.cpp
@@ -66,7 +66,7 @@ ErrorOr<NonnullRefPtr<Game>> Game::try_create()
     }
 
     auto color = Color::from_argb(Config::read_u32("Snake"sv, "Snake"sv, "BaseColor"sv, Color(Color::Green).value()));
-    auto skin_name = TRY(String::from_deprecated_string(Config::read_string("Snake"sv, "Snake"sv, "SnakeSkin"sv, "Classic"sv)));
+    auto skin_name = TRY(String::from_byte_string(Config::read_string("Snake"sv, "Snake"sv, "SnakeSkin"sv, "Classic"sv)));
     auto skin = TRY(SnakeSkin::create(skin_name, color));
 
     return adopt_nonnull_ref_or_enomem(new (nothrow) Game(move(food_bitmaps), color, skin_name, move(skin)));
@@ -275,7 +275,7 @@ void Game::game_over()
         text.append("\nThat's a new high score!"sv);
     }
     GUI::MessageBox::show(window(),
-        text.to_deprecated_string(),
+        text.to_byte_string(),
         "Game Over"sv,
         GUI::MessageBox::Type::Information);
 
diff --git a/Userland/Games/Snake/Skins/ImageSkin.cpp b/Userland/Games/Snake/Skins/ImageSkin.cpp
index 73ee0177f0d..608a73937f0 100644
--- a/Userland/Games/Snake/Skins/ImageSkin.cpp
+++ b/Userland/Games/Snake/Skins/ImageSkin.cpp
@@ -14,7 +14,7 @@ namespace Snake {
 
 ErrorOr<NonnullOwnPtr<ImageSkin>> ImageSkin::create(StringView skin_name)
 {
-    auto skin_directory = TRY(Core::Directory::create(DeprecatedString::formatted("/res/graphics/snake/skins/{}", skin_name), Core::Directory::CreateDirectories::No));
+    auto skin_directory = TRY(Core::Directory::create(ByteString::formatted("/res/graphics/snake/skins/{}", skin_name), Core::Directory::CreateDirectories::No));
 
     auto head = TRY(Gfx::Bitmap::load_from_file(TRY(skin_directory.open("head.png"sv, Core::File::OpenMode::Read)), "head.png"sv));
     Vector<NonnullRefPtr<Gfx::Bitmap>> head_bitmaps;
diff --git a/Userland/Games/Snake/main.cpp b/Userland/Games/Snake/main.cpp
index 6a25515095d..18e17af94c2 100644
--- a/Userland/Games/Snake/main.cpp
+++ b/Userland/Games/Snake/main.cpp
@@ -92,14 +92,14 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto const pause_icon = TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/pause.png"sv));
     static String const continue_text = "&Continue Game"_string;
     auto const continue_icon = TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/play.png"sv));
-    game_menu->add_action(GUI::Action::create(pause_text.to_deprecated_string(), { Mod_None, Key_Space }, pause_icon, [&](auto& action) {
+    game_menu->add_action(GUI::Action::create(pause_text.to_byte_string(), { Mod_None, Key_Space }, pause_icon, [&](auto& action) {
         if (game.has_timer()) {
             game.pause();
-            action.set_text(continue_text.to_deprecated_string());
+            action.set_text(continue_text.to_byte_string());
             action.set_icon(continue_icon);
         } else {
             game.start();
-            action.set_text(pause_text.to_deprecated_string());
+            action.set_text(pause_text.to_byte_string());
             action.set_icon(pause_icon);
         }
     }));
@@ -129,7 +129,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto add_skin_action = [&](StringView name, bool enable_color) -> ErrorOr<void> {
         auto action = GUI::Action::create_checkable(name, GUI::Shortcut {}, [&, enable_color](auto& action) {
             Config::write_string("Snake"sv, "Snake"sv, "SnakeSkin"sv, action.text());
-            game.set_skin_name(String::from_deprecated_string(action.text()).release_value_but_fixme_should_propagate_errors());
+            game.set_skin_name(String::from_byte_string(action.text()).release_value_but_fixme_should_propagate_errors());
             change_snake_color->set_enabled(enable_color);
         });
 
diff --git a/Userland/Libraries/LibAudio/FlacLoader.cpp b/Userland/Libraries/LibAudio/FlacLoader.cpp
index 0ebb485db79..6d809d65284 100644
--- a/Userland/Libraries/LibAudio/FlacLoader.cpp
+++ b/Userland/Libraries/LibAudio/FlacLoader.cpp
@@ -4,9 +4,9 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
 #include <AK/DeprecatedFlyString.h>
-#include <AK/DeprecatedString.h>
 #include <AK/FixedArray.h>
 #include <AK/Format.h>
 #include <AK/IntegralMath.h>
@@ -63,11 +63,11 @@ MaybeLoaderError FlacLoaderPlugin::parse_header()
     BigEndianInputBitStream bit_input { MaybeOwned<Stream>(*m_stream) };
 
     // A mixture of VERIFY and the non-crashing TRY().
-#define FLAC_VERIFY(check, category, msg)                                                                                \
-    do {                                                                                                                 \
-        if (!(check)) {                                                                                                  \
-            return LoaderError { category, TRY(m_stream->tell()), DeprecatedString::formatted("FLAC header: {}", msg) }; \
-        }                                                                                                                \
+#define FLAC_VERIFY(check, category, msg)                                                                          \
+    do {                                                                                                           \
+        if (!(check)) {                                                                                            \
+            return LoaderError { category, TRY(m_stream->tell()), ByteString::formatted("FLAC header: {}", msg) }; \
+        }                                                                                                          \
     } while (0)
 
     // Magic number
@@ -305,7 +305,7 @@ MaybeLoaderError FlacLoaderPlugin::seek(int int_sample_index)
             dbgln_if(AFLACLOADER_DEBUG, "Seeking to seektable: sample index {}, byte offset {}", target_seekpoint.sample_index, target_seekpoint.byte_offset);
             auto position = target_seekpoint.byte_offset + m_data_start_location;
             if (m_stream->seek(static_cast<i64>(position), SeekMode::SetPosition).is_error())
-                return LoaderError { LoaderError::Category::IO, m_loaded_samples, DeprecatedString::formatted("Invalid seek position {}", position) };
+                return LoaderError { LoaderError::Category::IO, m_loaded_samples, ByteString::formatted("Invalid seek position {}", position) };
             m_loaded_samples = target_seekpoint.sample_index;
         }
     }
@@ -367,11 +367,11 @@ ErrorOr<Vector<FixedArray<Sample>>, LoaderError> FlacLoaderPlugin::load_chunks(s
 // 11.21. FRAME
 LoaderSamples FlacLoaderPlugin::next_frame()
 {
-#define FLAC_VERIFY(check, category, msg)                                                                                                         \
-    do {                                                                                                                                          \
-        if (!(check)) {                                                                                                                           \
-            return LoaderError { category, static_cast<size_t>(m_current_sample_or_frame), DeprecatedString::formatted("FLAC header: {}", msg) }; \
-        }                                                                                                                                         \
+#define FLAC_VERIFY(check, category, msg)                                                                                                   \
+    do {                                                                                                                                    \
+        if (!(check)) {                                                                                                                     \
+            return LoaderError { category, static_cast<size_t>(m_current_sample_or_frame), ByteString::formatted("FLAC header: {}", msg) }; \
+        }                                                                                                                                   \
     } while (0)
 
     auto frame_byte_index = TRY(m_stream->tell());
@@ -612,7 +612,7 @@ ErrorOr<u8, LoaderError> FlacLoaderPlugin::convert_bit_depth_code(u8 bit_depth_c
     case 7:
         return 32;
     default:
-        return LoaderError { LoaderError::Category::Format, static_cast<size_t>(m_current_sample_or_frame), DeprecatedString::formatted("Unsupported sample size {}", bit_depth_code) };
+        return LoaderError { LoaderError::Category::Format, static_cast<size_t>(m_current_sample_or_frame), ByteString::formatted("Unsupported sample size {}", bit_depth_code) };
     }
 }
 
@@ -900,7 +900,7 @@ ErrorOr<Vector<i64>, LoaderError> FlacLoaderPlugin::decode_fixed_lpc(FlacSubfram
             decoded[i] += 4 * decoded[i - 1] - 6 * decoded[i - 2] + 4 * decoded[i - 3] - decoded[i - 4];
         break;
     default:
-        return LoaderError { LoaderError::Category::Format, static_cast<size_t>(m_current_sample_or_frame), DeprecatedString::formatted("Unrecognized predictor order {}", subframe.order) };
+        return LoaderError { LoaderError::Category::Format, static_cast<size_t>(m_current_sample_or_frame), ByteString::formatted("Unrecognized predictor order {}", subframe.order) };
     }
     return decoded;
 }
diff --git a/Userland/Libraries/LibAudio/FlacLoader.h b/Userland/Libraries/LibAudio/FlacLoader.h
index f1343406176..99b73c40da8 100644
--- a/Userland/Libraries/LibAudio/FlacLoader.h
+++ b/Userland/Libraries/LibAudio/FlacLoader.h
@@ -52,7 +52,7 @@ public:
     virtual int total_samples() override { return static_cast<int>(m_total_samples); }
     virtual u32 sample_rate() override { return m_sample_rate; }
     virtual u16 num_channels() override { return m_num_channels; }
-    virtual DeprecatedString format_name() override { return "FLAC (.flac)"; }
+    virtual ByteString format_name() override { return "FLAC (.flac)"; }
     virtual PcmSampleFormat pcm_format() override { return m_sample_format; }
 
     bool is_fixed_blocksize_stream() const { return m_min_block_size == m_max_block_size; }
diff --git a/Userland/Libraries/LibAudio/Loader.h b/Userland/Libraries/LibAudio/Loader.h
index e1f0d806796..ba7cc4a5409 100644
--- a/Userland/Libraries/LibAudio/Loader.h
+++ b/Userland/Libraries/LibAudio/Loader.h
@@ -70,7 +70,7 @@ public:
     virtual u16 num_channels() = 0;
 
     // Human-readable name of the file format, of the form <full abbreviation> (.<ending>)
-    virtual DeprecatedString format_name() = 0;
+    virtual ByteString format_name() = 0;
     virtual PcmSampleFormat pcm_format() = 0;
 
     Metadata const& metadata() const { return m_metadata; }
@@ -107,7 +107,7 @@ public:
     int total_samples() const { return m_plugin->total_samples(); }
     u32 sample_rate() const { return m_plugin->sample_rate(); }
     u16 num_channels() const { return m_plugin->num_channels(); }
-    DeprecatedString format_name() const { return m_plugin->format_name(); }
+    ByteString format_name() const { return m_plugin->format_name(); }
     u16 bits_per_sample() const { return pcm_bits_per_sample(m_plugin->pcm_format()); }
     PcmSampleFormat pcm_format() const { return m_plugin->pcm_format(); }
     Metadata const& metadata() const { return m_plugin->metadata(); }
diff --git a/Userland/Libraries/LibAudio/LoaderError.h b/Userland/Libraries/LibAudio/LoaderError.h
index 925b09fab36..252fe7a3cc6 100644
--- a/Userland/Libraries/LibAudio/LoaderError.h
+++ b/Userland/Libraries/LibAudio/LoaderError.h
@@ -28,7 +28,7 @@ struct LoaderError {
     Category category { Category::Unknown };
     // Binary index: where in the file the error occurred.
     size_t index { 0 };
-    DeprecatedFlyString description { DeprecatedString::empty() };
+    DeprecatedFlyString description { ByteString::empty() };
 
     constexpr LoaderError() = default;
     LoaderError(Category category, size_t index, DeprecatedFlyString description)
@@ -54,7 +54,7 @@ struct LoaderError {
     {
         if (error.is_errno()) {
             auto code = error.code();
-            description = DeprecatedString::formatted("{} ({})", strerror(code), code);
+            description = ByteString::formatted("{} ({})", strerror(code), code);
             if (code == EBADF || code == EBUSY || code == EEXIST || code == EIO || code == EISDIR || code == ENOENT || code == ENOMEM || code == EPIPE)
                 category = Category::IO;
         } else {
diff --git a/Userland/Libraries/LibAudio/MP3Loader.h b/Userland/Libraries/LibAudio/MP3Loader.h
index f841744bb0f..0787379bbcc 100644
--- a/Userland/Libraries/LibAudio/MP3Loader.h
+++ b/Userland/Libraries/LibAudio/MP3Loader.h
@@ -37,7 +37,7 @@ public:
     virtual u32 sample_rate() override { return m_sample_rate; }
     virtual u16 num_channels() override { return m_num_channels; }
     virtual PcmSampleFormat pcm_format() override { return m_sample_format; }
-    virtual DeprecatedString format_name() override { return "MP3 (.mp3)"; }
+    virtual ByteString format_name() override { return "MP3 (.mp3)"; }
 
 private:
     MaybeLoaderError initialize();
diff --git a/Userland/Libraries/LibAudio/QOALoader.h b/Userland/Libraries/LibAudio/QOALoader.h
index 385cb0abcfe..753ffe29e50 100644
--- a/Userland/Libraries/LibAudio/QOALoader.h
+++ b/Userland/Libraries/LibAudio/QOALoader.h
@@ -37,7 +37,7 @@ public:
     virtual int total_samples() override { return static_cast<int>(m_total_samples); }
     virtual u32 sample_rate() override { return m_sample_rate; }
     virtual u16 num_channels() override { return m_num_channels; }
-    virtual DeprecatedString format_name() override { return "Quite Okay Audio (.qoa)"; }
+    virtual ByteString format_name() override { return "Quite Okay Audio (.qoa)"; }
     virtual PcmSampleFormat pcm_format() override { return PcmSampleFormat::Int16; }
 
 private:
diff --git a/Userland/Libraries/LibAudio/SampleFormats.cpp b/Userland/Libraries/LibAudio/SampleFormats.cpp
index 73e2a4d2f55..3f750e61349 100644
--- a/Userland/Libraries/LibAudio/SampleFormats.cpp
+++ b/Userland/Libraries/LibAudio/SampleFormats.cpp
@@ -48,10 +48,10 @@ Optional<PcmSampleFormat> integer_sample_format_for(u16 bits_per_sample)
     }
 }
 
-DeprecatedString sample_format_name(PcmSampleFormat format)
+ByteString sample_format_name(PcmSampleFormat format)
 {
     bool is_float = format == PcmSampleFormat::Float32 || format == PcmSampleFormat::Float64;
-    return DeprecatedString::formatted("PCM {}bit {}", pcm_bits_per_sample(format), is_float ? "Float" : "LE");
+    return ByteString::formatted("PCM {}bit {}", pcm_bits_per_sample(format), is_float ? "Float" : "LE");
 }
 
 }
diff --git a/Userland/Libraries/LibAudio/SampleFormats.h b/Userland/Libraries/LibAudio/SampleFormats.h
index bccb20d7565..918a43e49a1 100644
--- a/Userland/Libraries/LibAudio/SampleFormats.h
+++ b/Userland/Libraries/LibAudio/SampleFormats.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Types.h>
 
 namespace Audio {
@@ -25,5 +25,5 @@ enum class PcmSampleFormat : u8 {
 u16 pcm_bits_per_sample(PcmSampleFormat format);
 bool is_integer_format(PcmSampleFormat format);
 Optional<PcmSampleFormat> integer_sample_format_for(u16 bits_per_sample);
-DeprecatedString sample_format_name(PcmSampleFormat format);
+ByteString sample_format_name(PcmSampleFormat format);
 }
diff --git a/Userland/Libraries/LibAudio/WavLoader.cpp b/Userland/Libraries/LibAudio/WavLoader.cpp
index f533ac92519..a5077361a27 100644
--- a/Userland/Libraries/LibAudio/WavLoader.cpp
+++ b/Userland/Libraries/LibAudio/WavLoader.cpp
@@ -178,11 +178,11 @@ MaybeLoaderError WavLoaderPlugin::seek(int sample_index)
 // Specification reference: http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/WAVE.html
 MaybeLoaderError WavLoaderPlugin::parse_header()
 {
-#define CHECK(check, category, msg)                                                                                                          \
-    do {                                                                                                                                     \
-        if (!(check)) {                                                                                                                      \
-            return LoaderError { category, static_cast<size_t>(TRY(m_stream->tell())), DeprecatedString::formatted("WAV header: {}", msg) }; \
-        }                                                                                                                                    \
+#define CHECK(check, category, msg)                                                                                                    \
+    do {                                                                                                                               \
+        if (!(check)) {                                                                                                                \
+            return LoaderError { category, static_cast<size_t>(TRY(m_stream->tell())), ByteString::formatted("WAV header: {}", msg) }; \
+        }                                                                                                                              \
     } while (0)
 
     auto riff = TRY(m_stream->read_value<RIFF::ChunkID>());
diff --git a/Userland/Libraries/LibAudio/WavLoader.h b/Userland/Libraries/LibAudio/WavLoader.h
index 49da79e685c..1a06c8c08cd 100644
--- a/Userland/Libraries/LibAudio/WavLoader.h
+++ b/Userland/Libraries/LibAudio/WavLoader.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/FixedArray.h>
 #include <AK/OwnPtr.h>
 #include <AK/RefPtr.h>
@@ -41,7 +41,7 @@ public:
     virtual int total_samples() override { return static_cast<int>(m_total_samples); }
     virtual u32 sample_rate() override { return m_sample_rate; }
     virtual u16 num_channels() override { return m_num_channels; }
-    virtual DeprecatedString format_name() override { return "RIFF WAVE (.wav)"; }
+    virtual ByteString format_name() override { return "RIFF WAVE (.wav)"; }
     virtual PcmSampleFormat pcm_format() override { return m_sample_format; }
 
 private:
diff --git a/Userland/Libraries/LibAudio/WavWriter.h b/Userland/Libraries/LibAudio/WavWriter.h
index 845eb7b06cb..d026833dad0 100644
--- a/Userland/Libraries/LibAudio/WavWriter.h
+++ b/Userland/Libraries/LibAudio/WavWriter.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Noncopyable.h>
 #include <AK/RefPtr.h>
 #include <AK/StringView.h>
diff --git a/Userland/Libraries/LibC/bits/dlfcn_integration.h b/Userland/Libraries/LibC/bits/dlfcn_integration.h
index 01421879063..1acf07cf13f 100644
--- a/Userland/Libraries/LibC/bits/dlfcn_integration.h
+++ b/Userland/Libraries/LibC/bits/dlfcn_integration.h
@@ -7,11 +7,11 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Result.h>
 
 struct DlErrorMessage {
-    DlErrorMessage(DeprecatedString&& other)
+    DlErrorMessage(ByteString&& other)
         : text(move(other))
     {
     }
@@ -21,7 +21,7 @@ struct DlErrorMessage {
     // from the one in libc.so
     virtual ~DlErrorMessage() = default;
 
-    DeprecatedString text;
+    ByteString text;
 };
 
 struct __Dl_info;
diff --git a/Userland/Libraries/LibC/dlfcn.cpp b/Userland/Libraries/LibC/dlfcn.cpp
index abbc722e44b..e5eecdfbf87 100644
--- a/Userland/Libraries/LibC/dlfcn.cpp
+++ b/Userland/Libraries/LibC/dlfcn.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Types.h>
 #include <bits/dlfcn_integration.h>
 #include <dlfcn.h>
@@ -25,7 +25,7 @@ __thread char* s_dlerror_text = NULL;
 __thread bool s_dlerror_retrieved = false;
 #endif
 
-static void store_error(DeprecatedString const& error)
+static void store_error(ByteString const& error)
 {
     free(s_dlerror_text);
     s_dlerror_text = strdup(error.characters());
diff --git a/Userland/Libraries/LibC/netdb.cpp b/Userland/Libraries/LibC/netdb.cpp
index c707a9b7151..f4dca809ed7 100644
--- a/Userland/Libraries/LibC/netdb.cpp
+++ b/Userland/Libraries/LibC/netdb.cpp
@@ -6,7 +6,7 @@
 
 #include <AK/Assertions.h>
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/ScopeGuard.h>
 #include <Kernel/Net/IPv4.h>
 #include <arpa/inet.h>
@@ -54,8 +54,8 @@ struct ServiceFileLine {
 
 static ErrorOr<Optional<ServiceFileLine>> parse_service_file_line(char const* line, ssize_t read);
 static servent __getserv_buffer;
-static DeprecatedString __getserv_name_buffer;
-static DeprecatedString __getserv_protocol_buffer;
+static ByteString __getserv_name_buffer;
+static ByteString __getserv_protocol_buffer;
 static int __getserv_port_buffer;
 static Vector<ByteBuffer> __getserv_alias_list_buffer;
 static Vector<char*> __getserv_alias_list;
@@ -68,7 +68,7 @@ static char const* protocols_path = "/etc/protocols";
 
 static bool fill_getproto_buffers(char const* line, ssize_t read);
 static protoent __getproto_buffer;
-static DeprecatedString __getproto_name_buffer;
+static ByteString __getproto_name_buffer;
 static Vector<ByteBuffer> __getproto_alias_list_buffer;
 static Vector<char*> __getproto_alias_list;
 static int __getproto_protocol_buffer;
@@ -96,7 +96,7 @@ static int connect_to_lookup_server()
     return fd;
 }
 
-static DeprecatedString gethostbyname_name_buffer;
+static ByteString gethostbyname_name_buffer;
 
 hostent* gethostbyname(char const* name)
 {
@@ -226,7 +226,7 @@ int gethostbyname_r(char const* __restrict name, struct hostent* __restrict ret,
     auto ipv4_address = IPv4Address::from_string({ name, strlen(name) });
 
     if (ipv4_address.has_value()) {
-        return populate_ret(ipv4_address.value().to_deprecated_string().characters(), ipv4_address.value().to_in_addr_t());
+        return populate_ret(ipv4_address.value().to_byte_string().characters(), ipv4_address.value().to_in_addr_t());
     }
 
     int fd = connect_to_lookup_server();
@@ -318,7 +318,7 @@ int gethostbyname_r(char const* __restrict name, struct hostent* __restrict ret,
     return populate_ret(name, address);
 }
 
-static DeprecatedString gethostbyaddr_name_buffer;
+static ByteString gethostbyaddr_name_buffer;
 
 hostent* gethostbyaddr(void const* addr, socklen_t addr_size, int type)
 {
@@ -474,9 +474,9 @@ struct servent* getservent()
 
     servent* service_entry = nullptr;
 
-    __getserv_name_buffer = service_file_line.value().name.to_deprecated_string();
+    __getserv_name_buffer = service_file_line.value().name.to_byte_string();
     __getserv_port_buffer = service_file_line.value().port;
-    __getserv_protocol_buffer = service_file_line.value().protocol.to_deprecated_string();
+    __getserv_protocol_buffer = service_file_line.value().protocol.to_byte_string();
     __getserv_alias_list_buffer = service_file_line.value().aliases;
 
     __getserv_buffer.s_name = const_cast<char*>(__getserv_name_buffer.characters());
@@ -583,9 +583,9 @@ static ErrorOr<Optional<ServiceFileLine>> parse_service_file_line(char const* li
     if (split_line.size() < 2)
         return Error::from_string_view("malformed service file"sv);
 
-    auto name = TRY(String::from_deprecated_string(split_line[0]));
+    auto name = TRY(String::from_byte_string(split_line[0]));
 
-    auto port_protocol = TRY(String::from_deprecated_string(split_line[1]));
+    auto port_protocol = TRY(String::from_byte_string(split_line[1]));
     auto port_protocol_split = TRY(port_protocol.split('/'));
 
     if (port_protocol_split.size() < 2)
@@ -756,7 +756,7 @@ void endprotoent()
 
 static bool fill_getproto_buffers(char const* line, ssize_t read)
 {
-    DeprecatedString string_line = DeprecatedString(line, read);
+    ByteString string_line = ByteString(line, read);
     auto split_line = string_line.replace(" "sv, "\t"sv, ReplaceMode::All).split('\t');
 
     // This indicates an incorrect file format. Protocols file entries should
diff --git a/Userland/Libraries/LibC/shadow.cpp b/Userland/Libraries/LibC/shadow.cpp
index 207c1240fd0..929fce23e06 100644
--- a/Userland/Libraries/LibC/shadow.cpp
+++ b/Userland/Libraries/LibC/shadow.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/TemporaryChange.h>
 #include <AK/Vector.h>
 #include <errno.h>
@@ -20,8 +20,8 @@ static FILE* s_stream = nullptr;
 static unsigned s_line_number = 0;
 static struct spwd s_shadow_entry;
 
-static DeprecatedString s_name;
-static DeprecatedString s_pwdp;
+static ByteString s_name;
+static ByteString s_pwdp;
 
 void setspent()
 {
@@ -61,7 +61,7 @@ struct spwd* getspnam(char const* name)
     return nullptr;
 }
 
-static bool parse_shadow_entry(DeprecatedString const& line)
+static bool parse_shadow_entry(ByteString const& line)
 {
     auto parts = line.split_view(':', SplitBehavior::KeepEmpty);
     if (parts.size() != 9) {
@@ -168,7 +168,7 @@ struct spwd* getspent()
         if ((!s || !s[0]) && feof(s_stream))
             return nullptr;
 
-        DeprecatedString line(s, Chomp);
+        ByteString line(s, Chomp);
         if (parse_shadow_entry(line))
             return &s_shadow_entry;
         // Otherwise, proceed to the next line.
diff --git a/Userland/Libraries/LibC/stdio.cpp b/Userland/Libraries/LibC/stdio.cpp
index a146ffba4da..32c6e5851c8 100644
--- a/Userland/Libraries/LibC/stdio.cpp
+++ b/Userland/Libraries/LibC/stdio.cpp
@@ -6,7 +6,7 @@
  */
 
 #include <AK/BuiltinWrappers.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/PrintfImplementation.h>
 #include <AK/ScopedValueRollback.h>
@@ -947,7 +947,7 @@ int vasprintf(char** strp, char const* fmt, va_list ap)
     builder.appendvf(fmt, ap);
     VERIFY(builder.length() <= NumericLimits<int>::max());
     int length = builder.length();
-    *strp = strdup(builder.to_deprecated_string().characters());
+    *strp = strdup(builder.to_byte_string().characters());
     return length;
 }
 
@@ -961,7 +961,7 @@ int asprintf(char** strp, char const* fmt, ...)
     va_end(ap);
     VERIFY(builder.length() <= NumericLimits<int>::max());
     int length = builder.length();
-    *strp = strdup(builder.to_deprecated_string().characters());
+    *strp = strdup(builder.to_byte_string().characters());
     return length;
 }
 
diff --git a/Userland/Libraries/LibC/stdlib.cpp b/Userland/Libraries/LibC/stdlib.cpp
index eb393b9bdcf..29325d555b1 100644
--- a/Userland/Libraries/LibC/stdlib.cpp
+++ b/Userland/Libraries/LibC/stdlib.cpp
@@ -649,7 +649,7 @@ int ptsname_r(int fd, char* buffer, size_t size)
         return -1;
     }
     memset(buffer, 0, devpts_path_builder.length() + 1);
-    auto full_devpts_path_string = devpts_path_builder.to_deprecated_string();
+    auto full_devpts_path_string = devpts_path_builder.to_byte_string();
     if (!full_devpts_path_string.copy_characters_to_buffer(buffer, size)) {
         errno = ERANGE;
         return -1;
diff --git a/Userland/Libraries/LibC/sys/devices/gpu.h b/Userland/Libraries/LibC/sys/devices/gpu.h
index e5eb843b79f..dadeeaf272e 100644
--- a/Userland/Libraries/LibC/sys/devices/gpu.h
+++ b/Userland/Libraries/LibC/sys/devices/gpu.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Platform.h>
 #include <AK/ScopeGuard.h>
 #include <fcntl.h>
@@ -34,7 +34,7 @@ ALWAYS_INLINE int graphics_connector_get_head_edid(int fd, GraphicsHeadEDID* inf
     }
     auto minor_number = minor(display_connector_stat.st_rdev);
 
-    auto edid_fd = open(DeprecatedString::formatted("/sys/devices/graphics/connectors/{}/edid", minor_number).characters(), O_RDONLY);
+    auto edid_fd = open(ByteString::formatted("/sys/devices/graphics/connectors/{}/edid", minor_number).characters(), O_RDONLY);
     if (edid_fd < 0) {
         return edid_fd;
     }
diff --git a/Userland/Libraries/LibC/syslog.cpp b/Userland/Libraries/LibC/syslog.cpp
index 5866b59ca7a..9131f0e60de 100644
--- a/Userland/Libraries/LibC/syslog.cpp
+++ b/Userland/Libraries/LibC/syslog.cpp
@@ -7,7 +7,7 @@
 // Has to be defined before including due to legacy Unices
 #define SYSLOG_NAMES 1
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <stdio.h>
 #include <string.h>
@@ -124,7 +124,7 @@ void vsyslog_r(int priority, struct syslog_data* data, char const* message, va_l
         combined.appendff("{}: ", get_syslog_ident(data));
 
     combined.appendvf(message, args);
-    auto combined_string = combined.to_deprecated_string();
+    auto combined_string = combined.to_byte_string();
 
     if (data->logopt & LOG_CONS)
         dbgputstr(combined_string.characters(), combined_string.length());
diff --git a/Userland/Libraries/LibC/time.cpp b/Userland/Libraries/LibC/time.cpp
index 34b7f9c9f66..67798b877d6 100644
--- a/Userland/Libraries/LibC/time.cpp
+++ b/Userland/Libraries/LibC/time.cpp
@@ -414,7 +414,7 @@ size_t strftime(char* destination, size_t max_size, char const* format, const st
             return 0;
     }
 
-    auto str = builder.to_deprecated_string();
+    auto str = builder.to_byte_string();
     bool fits = str.copy_characters_to_buffer(destination, max_size);
     return fits ? str.length() : 0;
 }
diff --git a/Userland/Libraries/LibC/unistd.cpp b/Userland/Libraries/LibC/unistd.cpp
index c187b795d39..4db929e3b9b 100644
--- a/Userland/Libraries/LibC/unistd.cpp
+++ b/Userland/Libraries/LibC/unistd.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/ScopeGuard.h>
 #include <AK/ScopedValueRollback.h>
 #include <AK/Vector.h>
@@ -190,12 +190,12 @@ int execvpe(char const* filename, char* const argv[], char* const envp[])
     ScopedValueRollback errno_rollback(errno);
 
     // TODO: Make this use the PATH search implementation from LibFileSystem.
-    DeprecatedString path = getenv("PATH");
+    ByteString path = getenv("PATH");
     if (path.is_empty())
         path = DEFAULT_PATH;
     auto parts = path.split(':');
     for (auto& part : parts) {
-        auto candidate = DeprecatedString::formatted("{}/{}", part, filename);
+        auto candidate = ByteString::formatted("{}/{}", part, filename);
         int rc = execve(candidate.characters(), argv, envp);
         if (rc < 0 && errno != ENOENT) {
             errno_rollback.set_override_rollback_value(errno);
@@ -881,13 +881,13 @@ void sync()
     syscall(SC_sync);
 }
 
-static Optional<DeprecatedString> getlogin_buffer {};
+static Optional<ByteString> getlogin_buffer {};
 
 char* getlogin()
 {
     if (!getlogin_buffer.has_value()) {
         if (auto* passwd = getpwuid(getuid())) {
-            getlogin_buffer = DeprecatedString(passwd->pw_name);
+            getlogin_buffer = ByteString(passwd->pw_name);
         }
         endpwent();
     }
diff --git a/Userland/Libraries/LibCards/CardPainter.cpp b/Userland/Libraries/LibCards/CardPainter.cpp
index bb403c1e529..498f4d1adba 100644
--- a/Userland/Libraries/LibCards/CardPainter.cpp
+++ b/Userland/Libraries/LibCards/CardPainter.cpp
@@ -24,8 +24,8 @@ CardPainter& CardPainter::the()
 
 CardPainter::CardPainter()
 {
-    m_back_image_path = MUST(String::from_deprecated_string(Config::read_string("Games"sv, "Cards"sv, "CardBackImage"sv, "/res/graphics/cards/backs/Red.png"sv)));
-    set_front_images_set_name(MUST(String::from_deprecated_string(Config::read_string("Games"sv, "Cards"sv, "CardFrontImages"sv, "Classic"sv))));
+    m_back_image_path = MUST(String::from_byte_string(Config::read_string("Games"sv, "Cards"sv, "CardBackImage"sv, "/res/graphics/cards/backs/Red.png"sv)));
+    set_front_images_set_name(MUST(String::from_byte_string(Config::read_string("Games"sv, "Cards"sv, "CardFrontImages"sv, "Classic"sv))));
 }
 
 static constexpr Gfx::CharacterBitmap s_diamond {
diff --git a/Userland/Libraries/LibCards/CardStack.h b/Userland/Libraries/LibCards/CardStack.h
index b65b7684d08..49b482de746 100644
--- a/Userland/Libraries/LibCards/CardStack.h
+++ b/Userland/Libraries/LibCards/CardStack.h
@@ -140,6 +140,6 @@ struct AK::Formatter<Cards::CardStack> : Formatter<FormatString> {
             first_card = false;
         }
 
-        return Formatter<FormatString>::format(builder, "{:<10} {:>16}: {}"sv, type, stack.bounding_box(), cards.to_deprecated_string());
+        return Formatter<FormatString>::format(builder, "{:<10} {:>16}: {}"sv, type, stack.bounding_box(), cards.to_byte_string());
     }
 };
diff --git a/Userland/Libraries/LibChess/UCIEndpoint.h b/Userland/Libraries/LibChess/UCIEndpoint.h
index 1aa31cdda18..406b65acff7 100644
--- a/Userland/Libraries/LibChess/UCIEndpoint.h
+++ b/Userland/Libraries/LibChess/UCIEndpoint.h
@@ -19,7 +19,7 @@ class Endpoint : public Core::EventReceiver {
 public:
     virtual ~Endpoint() override = default;
 
-    Function<void(DeprecatedString, Error)> on_command_read_error;
+    Function<void(ByteString, Error)> on_command_read_error;
 
     virtual void handle_uci() { }
     virtual void handle_debug(DebugCommand const&) { }
diff --git a/Userland/Libraries/LibCodeComprehension/CodeComprehensionEngine.cpp b/Userland/Libraries/LibCodeComprehension/CodeComprehensionEngine.cpp
index 432c91f0df9..ffeef2ecaf2 100644
--- a/Userland/Libraries/LibCodeComprehension/CodeComprehensionEngine.cpp
+++ b/Userland/Libraries/LibCodeComprehension/CodeComprehensionEngine.cpp
@@ -15,7 +15,7 @@ CodeComprehensionEngine::CodeComprehensionEngine(FileDB const& filedb, bool shou
 {
 }
 
-void CodeComprehensionEngine::set_declarations_of_document(DeprecatedString const& filename, Vector<Declaration>&& declarations)
+void CodeComprehensionEngine::set_declarations_of_document(ByteString const& filename, Vector<Declaration>&& declarations)
 {
     // Callback may not be configured if we're running tests
     if (!set_declarations_of_document_callback)
@@ -31,7 +31,7 @@ void CodeComprehensionEngine::set_declarations_of_document(DeprecatedString cons
     set_declarations_of_document_callback(filename, move(declarations));
 }
 
-void CodeComprehensionEngine::set_todo_entries_of_document(DeprecatedString const& filename, Vector<TodoEntry>&& todo_entries)
+void CodeComprehensionEngine::set_todo_entries_of_document(ByteString const& filename, Vector<TodoEntry>&& todo_entries)
 {
     // Callback may not be configured if we're running tests
     if (!set_todo_entries_of_document_callback)
diff --git a/Userland/Libraries/LibCodeComprehension/CodeComprehensionEngine.h b/Userland/Libraries/LibCodeComprehension/CodeComprehensionEngine.h
index e228b906823..b708cf410f3 100644
--- a/Userland/Libraries/LibCodeComprehension/CodeComprehensionEngine.h
+++ b/Userland/Libraries/LibCodeComprehension/CodeComprehensionEngine.h
@@ -24,33 +24,33 @@ public:
     CodeComprehensionEngine(FileDB const& filedb, bool store_all_declarations = false);
     virtual ~CodeComprehensionEngine() = default;
 
-    virtual Vector<AutocompleteResultEntry> get_suggestions(DeprecatedString const& file, GUI::TextPosition const& autocomplete_position) = 0;
+    virtual Vector<AutocompleteResultEntry> get_suggestions(ByteString const& file, GUI::TextPosition const& autocomplete_position) = 0;
 
     // TODO: In the future we can pass the range that was edited and only re-parse what we have to.
-    virtual void on_edit([[maybe_unused]] DeprecatedString const& file) {};
-    virtual void file_opened([[maybe_unused]] DeprecatedString const& file) {};
+    virtual void on_edit([[maybe_unused]] ByteString const& file) {};
+    virtual void file_opened([[maybe_unused]] ByteString const& file) {};
 
-    virtual Optional<ProjectLocation> find_declaration_of(DeprecatedString const&, GUI::TextPosition const&) { return {}; }
+    virtual Optional<ProjectLocation> find_declaration_of(ByteString const&, GUI::TextPosition const&) { return {}; }
 
     struct FunctionParamsHint {
-        Vector<DeprecatedString> params;
+        Vector<ByteString> params;
         size_t current_index { 0 };
     };
-    virtual Optional<FunctionParamsHint> get_function_params_hint(DeprecatedString const&, GUI::TextPosition const&) { return {}; }
+    virtual Optional<FunctionParamsHint> get_function_params_hint(ByteString const&, GUI::TextPosition const&) { return {}; }
 
-    virtual Vector<TokenInfo> get_tokens_info(DeprecatedString const&) { return {}; }
+    virtual Vector<TokenInfo> get_tokens_info(ByteString const&) { return {}; }
 
-    Function<void(DeprecatedString const&, Vector<Declaration>&&)> set_declarations_of_document_callback;
-    Function<void(DeprecatedString const&, Vector<TodoEntry>&&)> set_todo_entries_of_document_callback;
+    Function<void(ByteString const&, Vector<Declaration>&&)> set_declarations_of_document_callback;
+    Function<void(ByteString const&, Vector<TodoEntry>&&)> set_todo_entries_of_document_callback;
 
 protected:
     FileDB const& filedb() const { return m_filedb; }
-    void set_declarations_of_document(DeprecatedString const&, Vector<Declaration>&&);
-    void set_todo_entries_of_document(DeprecatedString const&, Vector<TodoEntry>&&);
-    HashMap<DeprecatedString, Vector<Declaration>> const& all_declarations() const { return m_all_declarations; }
+    void set_declarations_of_document(ByteString const&, Vector<Declaration>&&);
+    void set_todo_entries_of_document(ByteString const&, Vector<TodoEntry>&&);
+    HashMap<ByteString, Vector<Declaration>> const& all_declarations() const { return m_all_declarations; }
 
 private:
-    HashMap<DeprecatedString, Vector<Declaration>> m_all_declarations;
+    HashMap<ByteString, Vector<Declaration>> m_all_declarations;
     FileDB const& m_filedb;
     bool m_store_all_declarations { false };
 };
diff --git a/Userland/Libraries/LibCodeComprehension/Cpp/ConnectionFromClient.h b/Userland/Libraries/LibCodeComprehension/Cpp/ConnectionFromClient.h
index 2b8428eab51..3fea907fb70 100644
--- a/Userland/Libraries/LibCodeComprehension/Cpp/ConnectionFromClient.h
+++ b/Userland/Libraries/LibCodeComprehension/Cpp/ConnectionFromClient.h
@@ -19,10 +19,10 @@ private:
         : LanguageServers::ConnectionFromClient(move(socket))
     {
         m_autocomplete_engine = make<CodeComprehension::Cpp::CppComprehensionEngine>(m_filedb);
-        m_autocomplete_engine->set_declarations_of_document_callback = [this](DeprecatedString const& filename, Vector<CodeComprehension::Declaration>&& declarations) {
+        m_autocomplete_engine->set_declarations_of_document_callback = [this](ByteString const& filename, Vector<CodeComprehension::Declaration>&& declarations) {
             async_declarations_in_document(filename, move(declarations));
         };
-        m_autocomplete_engine->set_todo_entries_of_document_callback = [this](DeprecatedString const& filename, Vector<CodeComprehension::TodoEntry>&& todo_entries) {
+        m_autocomplete_engine->set_todo_entries_of_document_callback = [this](ByteString const& filename, Vector<CodeComprehension::TodoEntry>&& todo_entries) {
             async_todo_entries_in_document(filename, move(todo_entries));
         };
     }
diff --git a/Userland/Libraries/LibCodeComprehension/Cpp/CppComprehensionEngine.cpp b/Userland/Libraries/LibCodeComprehension/Cpp/CppComprehensionEngine.cpp
index 4d793d1d63f..e0b080b59e9 100644
--- a/Userland/Libraries/LibCodeComprehension/Cpp/CppComprehensionEngine.cpp
+++ b/Userland/Libraries/LibCodeComprehension/Cpp/CppComprehensionEngine.cpp
@@ -25,7 +25,7 @@ CppComprehensionEngine::CppComprehensionEngine(FileDB const& filedb)
 {
 }
 
-CppComprehensionEngine::DocumentData const* CppComprehensionEngine::get_or_create_document_data(DeprecatedString const& file)
+CppComprehensionEngine::DocumentData const* CppComprehensionEngine::get_or_create_document_data(ByteString const& file)
 {
     auto absolute_path = filedb().to_absolute_path(file);
     if (!m_documents.contains(absolute_path)) {
@@ -34,7 +34,7 @@ CppComprehensionEngine::DocumentData const* CppComprehensionEngine::get_or_creat
     return get_document_data(absolute_path);
 }
 
-CppComprehensionEngine::DocumentData const* CppComprehensionEngine::get_document_data(DeprecatedString const& file) const
+CppComprehensionEngine::DocumentData const* CppComprehensionEngine::get_document_data(ByteString const& file) const
 {
     auto absolute_path = filedb().to_absolute_path(file);
     auto document_data = m_documents.get(absolute_path);
@@ -43,7 +43,7 @@ CppComprehensionEngine::DocumentData const* CppComprehensionEngine::get_document
     return document_data.value();
 }
 
-OwnPtr<CppComprehensionEngine::DocumentData> CppComprehensionEngine::create_document_data_for(DeprecatedString const& file)
+OwnPtr<CppComprehensionEngine::DocumentData> CppComprehensionEngine::create_document_data_for(ByteString const& file)
 {
     if (m_unfinished_documents.contains(file)) {
         return {};
@@ -56,12 +56,12 @@ OwnPtr<CppComprehensionEngine::DocumentData> CppComprehensionEngine::create_docu
     return create_document_data(move(document.value()), file);
 }
 
-void CppComprehensionEngine::set_document_data(DeprecatedString const& file, OwnPtr<DocumentData>&& data)
+void CppComprehensionEngine::set_document_data(ByteString const& file, OwnPtr<DocumentData>&& data)
 {
     m_documents.set(filedb().to_absolute_path(file), move(data));
 }
 
-Vector<CodeComprehension::AutocompleteResultEntry> CppComprehensionEngine::get_suggestions(DeprecatedString const& file, const GUI::TextPosition& autocomplete_position)
+Vector<CodeComprehension::AutocompleteResultEntry> CppComprehensionEngine::get_suggestions(ByteString const& file, const GUI::TextPosition& autocomplete_position)
 {
     Cpp::Position position { autocomplete_position.line(), autocomplete_position.column() > 0 ? autocomplete_position.column() - 1 : 0 };
 
@@ -104,7 +104,7 @@ Vector<CodeComprehension::AutocompleteResultEntry> CppComprehensionEngine::get_s
 
 Optional<Vector<CodeComprehension::AutocompleteResultEntry>> CppComprehensionEngine::try_autocomplete_name(DocumentData const& document, ASTNode const& node, Optional<Token> containing_token) const
 {
-    auto partial_text = DeprecatedString::empty();
+    auto partial_text = ByteString::empty();
     if (containing_token.has_value() && containing_token.value().type() != Token::Type::ColonColon) {
         partial_text = containing_token.value().text();
     }
@@ -121,7 +121,7 @@ Optional<Vector<CodeComprehension::AutocompleteResultEntry>> CppComprehensionEng
 
     auto const& parent = static_cast<MemberExpression const&>(*node.parent());
 
-    auto partial_text = DeprecatedString::empty();
+    auto partial_text = ByteString::empty();
     if (containing_token.value().type() != Token::Type::Dot) {
         if (&node != parent.property())
             return {};
@@ -131,7 +131,7 @@ Optional<Vector<CodeComprehension::AutocompleteResultEntry>> CppComprehensionEng
     return autocomplete_property(document, parent, partial_text);
 }
 
-Vector<CodeComprehension::AutocompleteResultEntry> CppComprehensionEngine::autocomplete_name(DocumentData const& document, ASTNode const& node, DeprecatedString const& partial_text) const
+Vector<CodeComprehension::AutocompleteResultEntry> CppComprehensionEngine::autocomplete_name(DocumentData const& document, ASTNode const& node, ByteString const& partial_text) const
 {
     auto reference_scope = scope_of_reference_to_symbol(node);
     auto current_scope = scope_of_node(node);
@@ -206,7 +206,7 @@ Vector<StringView> CppComprehensionEngine::scope_of_reference_to_symbol(ASTNode
     return scope_parts;
 }
 
-Vector<CodeComprehension::AutocompleteResultEntry> CppComprehensionEngine::autocomplete_property(DocumentData const& document, MemberExpression const& parent, const DeprecatedString partial_text) const
+Vector<CodeComprehension::AutocompleteResultEntry> CppComprehensionEngine::autocomplete_property(DocumentData const& document, MemberExpression const& parent, const ByteString partial_text) const
 {
     VERIFY(parent.object());
     auto type = type_of(document, *parent.object());
@@ -233,7 +233,7 @@ bool CppComprehensionEngine::is_property(ASTNode const& node) const
     return parent.property() == &node;
 }
 
-DeprecatedString CppComprehensionEngine::type_of_property(DocumentData const& document, Identifier const& identifier) const
+ByteString CppComprehensionEngine::type_of_property(DocumentData const& document, Identifier const& identifier) const
 {
     auto& parent = verify_cast<MemberExpression>(*identifier.parent());
     VERIFY(parent.object());
@@ -253,12 +253,12 @@ DeprecatedString CppComprehensionEngine::type_of_property(DocumentData const& do
         VERIFY(verify_cast<NamedType>(*type).name());
         if (verify_cast<NamedType>(*type).name())
             return verify_cast<NamedType>(*type).name()->full_name();
-        return DeprecatedString::empty();
+        return ByteString::empty();
     }
     return {};
 }
 
-DeprecatedString CppComprehensionEngine::type_of_variable(Identifier const& identifier) const
+ByteString CppComprehensionEngine::type_of_variable(Identifier const& identifier) const
 {
     ASTNode const* current = &identifier;
     while (current) {
@@ -269,7 +269,7 @@ DeprecatedString CppComprehensionEngine::type_of_variable(Identifier const& iden
                     VERIFY(verify_cast<NamedType>(*var_or_param.type()).name());
                     if (verify_cast<NamedType>(*var_or_param.type()).name())
                         return verify_cast<NamedType>(*var_or_param.type()).name()->full_name();
-                    return DeprecatedString::empty();
+                    return ByteString::empty();
                 }
             }
         }
@@ -278,7 +278,7 @@ DeprecatedString CppComprehensionEngine::type_of_variable(Identifier const& iden
     return {};
 }
 
-DeprecatedString CppComprehensionEngine::type_of(DocumentData const& document, Expression const& expression) const
+ByteString CppComprehensionEngine::type_of(DocumentData const& document, Expression const& expression) const
 {
     if (expression.is_member_expression()) {
         auto& member_expression = verify_cast<MemberExpression>(expression);
@@ -304,7 +304,7 @@ DeprecatedString CppComprehensionEngine::type_of(DocumentData const& document, E
     return type_of_variable(*identifier);
 }
 
-Vector<CppComprehensionEngine::Symbol> CppComprehensionEngine::properties_of_type(DocumentData const& document, DeprecatedString const& type) const
+Vector<CppComprehensionEngine::Symbol> CppComprehensionEngine::properties_of_type(DocumentData const& document, ByteString const& type) const
 {
     auto type_symbol = SymbolName::create(type);
     auto decl = find_declaration_of(document, type_symbol);
@@ -362,21 +362,21 @@ Vector<CppComprehensionEngine::Symbol> CppComprehensionEngine::get_child_symbols
     return symbols;
 }
 
-DeprecatedString CppComprehensionEngine::document_path_from_include_path(StringView include_path) const
+ByteString CppComprehensionEngine::document_path_from_include_path(StringView include_path) const
 {
     static Regex<PosixExtended> library_include("<(.+)>");
     static Regex<PosixExtended> user_defined_include("\"(.+)\"");
 
-    auto document_path_for_library_include = [&](StringView include_path) -> DeprecatedString {
+    auto document_path_for_library_include = [&](StringView include_path) -> ByteString {
         RegexResult result;
         if (!library_include.search(include_path, result))
             return {};
 
         auto path = result.capture_group_matches.at(0).at(0).view.string_view();
-        return DeprecatedString::formatted("/usr/include/{}", path);
+        return ByteString::formatted("/usr/include/{}", path);
     };
 
-    auto document_path_for_user_defined_include = [&](StringView include_path) -> DeprecatedString {
+    auto document_path_for_user_defined_include = [&](StringView include_path) -> ByteString {
         RegexResult result;
         if (!user_defined_include.search(include_path, result))
             return {};
@@ -391,17 +391,17 @@ DeprecatedString CppComprehensionEngine::document_path_from_include_path(StringV
     return result;
 }
 
-void CppComprehensionEngine::on_edit(DeprecatedString const& file)
+void CppComprehensionEngine::on_edit(ByteString const& file)
 {
     set_document_data(file, create_document_data_for(file));
 }
 
-void CppComprehensionEngine::file_opened([[maybe_unused]] DeprecatedString const& file)
+void CppComprehensionEngine::file_opened([[maybe_unused]] ByteString const& file)
 {
     get_or_create_document_data(file);
 }
 
-Optional<CodeComprehension::ProjectLocation> CppComprehensionEngine::find_declaration_of(DeprecatedString const& filename, const GUI::TextPosition& identifier_position)
+Optional<CodeComprehension::ProjectLocation> CppComprehensionEngine::find_declaration_of(ByteString const& filename, const GUI::TextPosition& identifier_position)
 {
     auto const* document_ptr = get_or_create_document_data(filename);
     if (!document_ptr)
@@ -456,10 +456,10 @@ struct TargetDeclaration {
         Property,
         Scope
     } type;
-    DeprecatedString name;
+    ByteString name;
 };
 
-static Optional<TargetDeclaration> get_target_declaration(ASTNode const& node, DeprecatedString name);
+static Optional<TargetDeclaration> get_target_declaration(ASTNode const& node, ByteString name);
 static Optional<TargetDeclaration> get_target_declaration(ASTNode const& node)
 {
     if (node.is_identifier()) {
@@ -478,7 +478,7 @@ static Optional<TargetDeclaration> get_target_declaration(ASTNode const& node)
     return {};
 }
 
-static Optional<TargetDeclaration> get_target_declaration(ASTNode const& node, DeprecatedString name)
+static Optional<TargetDeclaration> get_target_declaration(ASTNode const& node, ByteString name)
 {
     if (node.parent() && node.parent()->is_name()) {
         auto& name_node = *verify_cast<Name>(node.parent());
@@ -612,7 +612,7 @@ CodeComprehension::DeclarationType CppComprehensionEngine::type_of_declaration(C
     return CodeComprehension::DeclarationType::Variable;
 }
 
-OwnPtr<CppComprehensionEngine::DocumentData> CppComprehensionEngine::create_document_data(DeprecatedString text, DeprecatedString const& filename)
+OwnPtr<CppComprehensionEngine::DocumentData> CppComprehensionEngine::create_document_data(ByteString text, ByteString const& filename)
 {
     auto document_data = make<DocumentData>();
     document_data->m_filename = filename;
@@ -693,7 +693,7 @@ Optional<Vector<CodeComprehension::AutocompleteResultEntry>> CppComprehensionEng
         System,
     } include_type { Project };
 
-    DeprecatedString include_root;
+    ByteString include_root;
     bool already_has_suffix = false;
     if (partial_include.starts_with('<')) {
         include_root = "/usr/include/";
@@ -716,7 +716,7 @@ Optional<Vector<CodeComprehension::AutocompleteResultEntry>> CppComprehensionEng
         return {};
 
     auto last_slash = partial_include.find_last('/');
-    auto include_dir = DeprecatedString::empty();
+    auto include_dir = ByteString::empty();
     auto partial_basename = partial_include.substring_view((last_slash.has_value() ? last_slash.value() : 0) + 1);
     if (last_slash.has_value()) {
         include_dir = partial_include.substring_view(1, last_slash.value());
@@ -738,12 +738,12 @@ Optional<Vector<CodeComprehension::AutocompleteResultEntry>> CppComprehensionEng
 
         if (FileSystem::is_directory(LexicalPath::join(full_dir, path).string())) {
             // FIXME: Don't dismiss the autocomplete when filling these suggestions.
-            auto completion = DeprecatedString::formatted("{}{}{}/", prefix, include_dir, path);
+            auto completion = ByteString::formatted("{}{}{}/", prefix, include_dir, path);
             options.empend(completion, include_dir.length() + partial_basename.length() + 1, CodeComprehension::Language::Cpp, path, CodeComprehension::AutocompleteResultEntry::HideAutocompleteAfterApplying::No);
         } else if (path.ends_with(".h"sv)) {
             // FIXME: Place the cursor after the trailing > or ", even if it was
             //        already typed.
-            auto completion = DeprecatedString::formatted("{}{}{}{}", prefix, include_dir, path, already_has_suffix ? "" : suffix);
+            auto completion = ByteString::formatted("{}{}{}{}", prefix, include_dir, path, already_has_suffix ? "" : suffix);
             options.empend(completion, include_dir.length() + partial_basename.length() + 1, CodeComprehension::Language::Cpp, path);
         }
     }
@@ -764,17 +764,17 @@ RefPtr<Cpp::Declaration const> CppComprehensionEngine::find_declaration_of(CppCo
     return target_declaration;
 }
 
-DeprecatedString CppComprehensionEngine::SymbolName::scope_as_string() const
+ByteString CppComprehensionEngine::SymbolName::scope_as_string() const
 {
     if (scope.is_empty())
-        return DeprecatedString::empty();
+        return ByteString::empty();
 
     StringBuilder builder;
     for (size_t i = 0; i < scope.size() - 1; ++i) {
         builder.appendff("{}::", scope[i]);
     }
     builder.append(scope.last());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 CppComprehensionEngine::SymbolName CppComprehensionEngine::SymbolName::create(StringView name, Vector<StringView>&& scope)
@@ -790,11 +790,11 @@ CppComprehensionEngine::SymbolName CppComprehensionEngine::SymbolName::create(St
     return SymbolName::create(name, move(parts));
 }
 
-DeprecatedString CppComprehensionEngine::SymbolName::to_deprecated_string() const
+ByteString CppComprehensionEngine::SymbolName::to_byte_string() const
 {
     if (scope.is_empty())
         return name;
-    return DeprecatedString::formatted("{}::{}", scope_as_string(), name);
+    return ByteString::formatted("{}::{}", scope_as_string(), name);
 }
 
 bool CppComprehensionEngine::is_symbol_available(Symbol const& symbol, Vector<StringView> const& current_scope, Vector<StringView> const& reference_scope)
@@ -818,7 +818,7 @@ bool CppComprehensionEngine::is_symbol_available(Symbol const& symbol, Vector<St
     return true;
 }
 
-Optional<CodeComprehensionEngine::FunctionParamsHint> CppComprehensionEngine::get_function_params_hint(DeprecatedString const& filename, const GUI::TextPosition& identifier_position)
+Optional<CodeComprehensionEngine::FunctionParamsHint> CppComprehensionEngine::get_function_params_hint(ByteString const& filename, const GUI::TextPosition& identifier_position)
 {
     auto const* document_ptr = get_or_create_document_data(filename);
     if (!document_ptr)
@@ -923,13 +923,13 @@ Optional<CppComprehensionEngine::FunctionParamsHint> CppComprehensionEngine::get
         for (auto token : document_of_declaration->parser().tokens_in_range(arg->start(), arg->end())) {
             tokens_text.append(token.text());
         }
-        hint.params.append(DeprecatedString::join(' ', tokens_text));
+        hint.params.append(ByteString::join(' ', tokens_text));
     }
 
     return hint;
 }
 
-Vector<CodeComprehension::TokenInfo> CppComprehensionEngine::get_tokens_info(DeprecatedString const& filename)
+Vector<CodeComprehension::TokenInfo> CppComprehensionEngine::get_tokens_info(ByteString const& filename)
 {
     dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "CppComprehensionEngine::get_tokens_info: {}", filename);
 
diff --git a/Userland/Libraries/LibCodeComprehension/Cpp/CppComprehensionEngine.h b/Userland/Libraries/LibCodeComprehension/Cpp/CppComprehensionEngine.h
index 43f24cb4f20..c6580613e96 100644
--- a/Userland/Libraries/LibCodeComprehension/Cpp/CppComprehensionEngine.h
+++ b/Userland/Libraries/LibCodeComprehension/Cpp/CppComprehensionEngine.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/Vector.h>
 #include <DevTools/HackStudio/AutoCompleteResponse.h>
@@ -25,12 +25,12 @@ class CppComprehensionEngine : public CodeComprehensionEngine {
 public:
     CppComprehensionEngine(FileDB const& filedb);
 
-    virtual Vector<CodeComprehension::AutocompleteResultEntry> get_suggestions(DeprecatedString const& file, GUI::TextPosition const& autocomplete_position) override;
-    virtual void on_edit(DeprecatedString const& file) override;
-    virtual void file_opened([[maybe_unused]] DeprecatedString const& file) override;
-    virtual Optional<CodeComprehension::ProjectLocation> find_declaration_of(DeprecatedString const& filename, GUI::TextPosition const& identifier_position) override;
-    virtual Optional<FunctionParamsHint> get_function_params_hint(DeprecatedString const&, GUI::TextPosition const&) override;
-    virtual Vector<CodeComprehension::TokenInfo> get_tokens_info(DeprecatedString const& filename) override;
+    virtual Vector<CodeComprehension::AutocompleteResultEntry> get_suggestions(ByteString const& file, GUI::TextPosition const& autocomplete_position) override;
+    virtual void on_edit(ByteString const& file) override;
+    virtual void file_opened([[maybe_unused]] ByteString const& file) override;
+    virtual Optional<CodeComprehension::ProjectLocation> find_declaration_of(ByteString const& filename, GUI::TextPosition const& identifier_position) override;
+    virtual Optional<FunctionParamsHint> get_function_params_hint(ByteString const&, GUI::TextPosition const&) override;
+    virtual Vector<CodeComprehension::TokenInfo> get_tokens_info(ByteString const& filename) override;
 
 private:
     struct SymbolName {
@@ -39,8 +39,8 @@ private:
 
         static SymbolName create(StringView, Vector<StringView>&&);
         static SymbolName create(StringView);
-        DeprecatedString scope_as_string() const;
-        DeprecatedString to_deprecated_string() const;
+        ByteString scope_as_string() const;
+        ByteString to_byte_string() const;
 
         bool operator==(SymbolName const&) const = default;
     };
@@ -63,8 +63,8 @@ private:
     friend Traits<SymbolName>;
 
     struct DocumentData {
-        DeprecatedString const& filename() const { return m_filename; }
-        DeprecatedString const& text() const { return m_text; }
+        ByteString const& filename() const { return m_filename; }
+        ByteString const& text() const { return m_text; }
         Preprocessor const& preprocessor() const
         {
             VERIFY(m_preprocessor);
@@ -86,20 +86,20 @@ private:
             return *m_parser;
         }
 
-        DeprecatedString m_filename;
-        DeprecatedString m_text;
+        ByteString m_filename;
+        ByteString m_text;
         OwnPtr<Preprocessor> m_preprocessor;
         OwnPtr<Parser> m_parser;
 
         HashMap<SymbolName, Symbol> m_symbols;
-        HashTable<DeprecatedString> m_available_headers;
+        HashTable<ByteString> m_available_headers;
     };
 
-    Vector<CodeComprehension::AutocompleteResultEntry> autocomplete_property(DocumentData const&, MemberExpression const&, const DeprecatedString partial_text) const;
-    Vector<AutocompleteResultEntry> autocomplete_name(DocumentData const&, ASTNode const&, DeprecatedString const& partial_text) const;
-    DeprecatedString type_of(DocumentData const&, Expression const&) const;
-    DeprecatedString type_of_property(DocumentData const&, Identifier const&) const;
-    DeprecatedString type_of_variable(Identifier const&) const;
+    Vector<CodeComprehension::AutocompleteResultEntry> autocomplete_property(DocumentData const&, MemberExpression const&, const ByteString partial_text) const;
+    Vector<AutocompleteResultEntry> autocomplete_name(DocumentData const&, ASTNode const&, ByteString const& partial_text) const;
+    ByteString type_of(DocumentData const&, Expression const&) const;
+    ByteString type_of_property(DocumentData const&, Identifier const&) const;
+    ByteString type_of_variable(Identifier const&) const;
     bool is_property(ASTNode const&) const;
     RefPtr<Cpp::Declaration const> find_declaration_of(DocumentData const&, ASTNode const&) const;
     RefPtr<Cpp::Declaration const> find_declaration_of(DocumentData const&, SymbolName const&) const;
@@ -110,16 +110,16 @@ private:
         Yes
     };
 
-    Vector<Symbol> properties_of_type(DocumentData const& document, DeprecatedString const& type) const;
+    Vector<Symbol> properties_of_type(DocumentData const& document, ByteString const& type) const;
     Vector<Symbol> get_child_symbols(ASTNode const&) const;
     Vector<Symbol> get_child_symbols(ASTNode const&, Vector<StringView> const& scope, Symbol::IsLocal) const;
 
-    DocumentData const* get_document_data(DeprecatedString const& file) const;
-    DocumentData const* get_or_create_document_data(DeprecatedString const& file);
-    void set_document_data(DeprecatedString const& file, OwnPtr<DocumentData>&& data);
+    DocumentData const* get_document_data(ByteString const& file) const;
+    DocumentData const* get_or_create_document_data(ByteString const& file);
+    void set_document_data(ByteString const& file, OwnPtr<DocumentData>&& data);
 
-    OwnPtr<DocumentData> create_document_data_for(DeprecatedString const& file);
-    DeprecatedString document_path_from_include_path(StringView include_path) const;
+    OwnPtr<DocumentData> create_document_data_for(ByteString const& file);
+    ByteString document_path_from_include_path(StringView include_path) const;
     void update_declared_symbols(DocumentData&);
     void update_todo_entries(DocumentData&);
     CodeComprehension::DeclarationType type_of_declaration(Cpp::Declaration const&);
@@ -129,7 +129,7 @@ private:
     Optional<CodeComprehension::ProjectLocation> find_preprocessor_definition(DocumentData const&, const GUI::TextPosition&);
     Optional<Cpp::Preprocessor::Substitution> find_preprocessor_substitution(DocumentData const&, Cpp::Position const&);
 
-    OwnPtr<DocumentData> create_document_data(DeprecatedString text, DeprecatedString const& filename);
+    OwnPtr<DocumentData> create_document_data(ByteString text, ByteString const& filename);
     Optional<Vector<CodeComprehension::AutocompleteResultEntry>> try_autocomplete_property(DocumentData const&, ASTNode const&, Optional<Token> containing_token) const;
     Optional<Vector<CodeComprehension::AutocompleteResultEntry>> try_autocomplete_name(DocumentData const&, ASTNode const&, Optional<Token> containing_token) const;
     Optional<Vector<CodeComprehension::AutocompleteResultEntry>> try_autocomplete_include(DocumentData const&, Token include_path_token, Cpp::Position const& cursor_position) const;
@@ -145,12 +145,12 @@ private:
     CodeComprehension::TokenInfo::SemanticType get_token_semantic_type(DocumentData const&, Token const&);
     CodeComprehension::TokenInfo::SemanticType get_semantic_type_for_identifier(DocumentData const&, Position);
 
-    HashMap<DeprecatedString, OwnPtr<DocumentData>> m_documents;
+    HashMap<ByteString, OwnPtr<DocumentData>> m_documents;
 
     // A document's path will be in this set if we're currently processing it.
     // A document is added to this set when we start processing it (e.g because it was #included) and removed when we're done.
     // We use this to prevent circular #includes from looping indefinitely.
-    HashTable<DeprecatedString> m_unfinished_documents;
+    HashTable<ByteString> m_unfinished_documents;
 };
 
 template<typename Func>
diff --git a/Userland/Libraries/LibCodeComprehension/Cpp/Tests.cpp b/Userland/Libraries/LibCodeComprehension/Cpp/Tests.cpp
index 84a7774ab04..38ff863f21e 100644
--- a/Userland/Libraries/LibCodeComprehension/Cpp/Tests.cpp
+++ b/Userland/Libraries/LibCodeComprehension/Cpp/Tests.cpp
@@ -44,14 +44,14 @@ class FileDB : public CodeComprehension::FileDB {
 public:
     FileDB() = default;
 
-    void add(DeprecatedString filename, DeprecatedString content)
+    void add(ByteString filename, ByteString content)
     {
         m_map.set(filename, content);
     }
 
-    virtual Optional<DeprecatedString> get_or_read_from_filesystem(StringView filename) const override
+    virtual Optional<ByteString> get_or_read_from_filesystem(StringView filename) const override
     {
-        DeprecatedString target_filename = filename;
+        ByteString target_filename = filename;
         if (project_root().has_value() && filename.starts_with(*project_root())) {
             target_filename = LexicalPath::relative_path(filename, *project_root());
         }
@@ -59,7 +59,7 @@ public:
     }
 
 private:
-    HashMap<DeprecatedString, DeprecatedString> m_map;
+    HashMap<ByteString, ByteString> m_map;
 };
 
 static void test_complete_local_args();
@@ -86,10 +86,10 @@ int run_tests()
     return 0;
 }
 
-static void add_file(FileDB& filedb, DeprecatedString const& name)
+static void add_file(FileDB& filedb, ByteString const& name)
 {
     auto file = Core::File::open(LexicalPath::join(TESTS_ROOT_DIR, name).string(), Core::File::OpenMode::Read).release_value_but_fixme_should_propagate_errors();
-    filedb.add(name, DeprecatedString::copy(MUST(file->read_until_eof())));
+    filedb.add(name, ByteString::copy(MUST(file->read_until_eof())));
 }
 
 void test_complete_local_args()
@@ -246,19 +246,19 @@ void test_parameters_hint()
     auto result = engine.get_function_params_hint("parameters_hint1.cpp", { 4, 9 });
     if (!result.has_value())
         FAIL("failed to get parameters hint (1)");
-    if (result->params != Vector<DeprecatedString> { "int x", "char y" } || result->current_index != 0)
+    if (result->params != Vector<ByteString> { "int x", "char y" } || result->current_index != 0)
         FAIL("bad result (1)");
 
     result = engine.get_function_params_hint("parameters_hint1.cpp", { 5, 15 });
     if (!result.has_value())
         FAIL("failed to get parameters hint (2)");
-    if (result->params != Vector<DeprecatedString> { "int x", "char y" } || result->current_index != 1)
+    if (result->params != Vector<ByteString> { "int x", "char y" } || result->current_index != 1)
         FAIL("bad result (2)");
 
     result = engine.get_function_params_hint("parameters_hint1.cpp", { 6, 8 });
     if (!result.has_value())
         FAIL("failed to get parameters hint (3)");
-    if (result->params != Vector<DeprecatedString> { "int x", "char y" } || result->current_index != 0)
+    if (result->params != Vector<ByteString> { "int x", "char y" } || result->current_index != 0)
         FAIL("bad result (3)");
 
     PASS;
diff --git a/Userland/Libraries/LibCodeComprehension/FileDB.cpp b/Userland/Libraries/LibCodeComprehension/FileDB.cpp
index 684527c366f..8273b00c58d 100644
--- a/Userland/Libraries/LibCodeComprehension/FileDB.cpp
+++ b/Userland/Libraries/LibCodeComprehension/FileDB.cpp
@@ -9,14 +9,14 @@
 
 namespace CodeComprehension {
 
-DeprecatedString FileDB::to_absolute_path(StringView filename) const
+ByteString FileDB::to_absolute_path(StringView filename) const
 {
     if (LexicalPath { filename }.is_absolute()) {
         return filename;
     }
     if (!m_project_root.has_value())
         return filename;
-    return LexicalPath { DeprecatedString::formatted("{}/{}", *m_project_root, filename) }.string();
+    return LexicalPath { ByteString::formatted("{}/{}", *m_project_root, filename) }.string();
 }
 
 }
diff --git a/Userland/Libraries/LibCodeComprehension/FileDB.h b/Userland/Libraries/LibCodeComprehension/FileDB.h
index 1947be59a28..efa599a7219 100644
--- a/Userland/Libraries/LibCodeComprehension/FileDB.h
+++ b/Userland/Libraries/LibCodeComprehension/FileDB.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringView.h>
 
 namespace CodeComprehension {
@@ -18,7 +18,7 @@ class FileDB {
 public:
     virtual ~FileDB() = default;
 
-    virtual Optional<DeprecatedString> get_or_read_from_filesystem(StringView filename) const = 0;
+    virtual Optional<ByteString> get_or_read_from_filesystem(StringView filename) const = 0;
     void set_project_root(StringView project_root)
     {
         if (project_root.is_null())
@@ -26,14 +26,14 @@ public:
         else
             m_project_root = project_root;
     }
-    Optional<DeprecatedString> const& project_root() const { return m_project_root; }
-    DeprecatedString to_absolute_path(StringView filename) const;
+    Optional<ByteString> const& project_root() const { return m_project_root; }
+    ByteString to_absolute_path(StringView filename) const;
 
 protected:
     FileDB() = default;
 
 private:
-    Optional<DeprecatedString> m_project_root;
+    Optional<ByteString> m_project_root;
 };
 
 }
diff --git a/Userland/Libraries/LibCodeComprehension/Shell/ConnectionFromClient.h b/Userland/Libraries/LibCodeComprehension/Shell/ConnectionFromClient.h
index e461bc51eab..e0694d7d8c6 100644
--- a/Userland/Libraries/LibCodeComprehension/Shell/ConnectionFromClient.h
+++ b/Userland/Libraries/LibCodeComprehension/Shell/ConnectionFromClient.h
@@ -20,10 +20,10 @@ private:
         : LanguageServers::ConnectionFromClient(move(socket))
     {
         m_autocomplete_engine = make<CodeComprehension::Shell::ShellComprehensionEngine>(m_filedb);
-        m_autocomplete_engine->set_declarations_of_document_callback = [this](DeprecatedString const& filename, Vector<CodeComprehension::Declaration>&& declarations) {
+        m_autocomplete_engine->set_declarations_of_document_callback = [this](ByteString const& filename, Vector<CodeComprehension::Declaration>&& declarations) {
             async_declarations_in_document(filename, move(declarations));
         };
-        m_autocomplete_engine->set_todo_entries_of_document_callback = [this](DeprecatedString const& filename, Vector<CodeComprehension::TodoEntry>&& todo_entries) {
+        m_autocomplete_engine->set_todo_entries_of_document_callback = [this](ByteString const& filename, Vector<CodeComprehension::TodoEntry>&& todo_entries) {
             async_todo_entries_in_document(filename, move(todo_entries));
         };
     }
diff --git a/Userland/Libraries/LibCodeComprehension/Shell/ShellComprehensionEngine.cpp b/Userland/Libraries/LibCodeComprehension/Shell/ShellComprehensionEngine.cpp
index 8caa8ad8dbb..1f863a9e81a 100644
--- a/Userland/Libraries/LibCodeComprehension/Shell/ShellComprehensionEngine.cpp
+++ b/Userland/Libraries/LibCodeComprehension/Shell/ShellComprehensionEngine.cpp
@@ -18,7 +18,7 @@ ShellComprehensionEngine::ShellComprehensionEngine(FileDB const& filedb)
 {
 }
 
-ShellComprehensionEngine::DocumentData const& ShellComprehensionEngine::get_or_create_document_data(DeprecatedString const& file)
+ShellComprehensionEngine::DocumentData const& ShellComprehensionEngine::get_or_create_document_data(ByteString const& file)
 {
     auto absolute_path = filedb().to_absolute_path(file);
     if (!m_documents.contains(absolute_path)) {
@@ -27,7 +27,7 @@ ShellComprehensionEngine::DocumentData const& ShellComprehensionEngine::get_or_c
     return get_document_data(absolute_path);
 }
 
-ShellComprehensionEngine::DocumentData const& ShellComprehensionEngine::get_document_data(DeprecatedString const& file) const
+ShellComprehensionEngine::DocumentData const& ShellComprehensionEngine::get_document_data(ByteString const& file) const
 {
     auto absolute_path = filedb().to_absolute_path(file);
     auto document_data = m_documents.get(absolute_path);
@@ -35,7 +35,7 @@ ShellComprehensionEngine::DocumentData const& ShellComprehensionEngine::get_docu
     return *document_data.value();
 }
 
-OwnPtr<ShellComprehensionEngine::DocumentData> ShellComprehensionEngine::create_document_data_for(DeprecatedString const& file)
+OwnPtr<ShellComprehensionEngine::DocumentData> ShellComprehensionEngine::create_document_data_for(ByteString const& file)
 {
     auto document = filedb().get_or_read_from_filesystem(file);
     if (!document.has_value())
@@ -50,19 +50,19 @@ OwnPtr<ShellComprehensionEngine::DocumentData> ShellComprehensionEngine::create_
     return document_data;
 }
 
-void ShellComprehensionEngine::set_document_data(DeprecatedString const& file, OwnPtr<DocumentData>&& data)
+void ShellComprehensionEngine::set_document_data(ByteString const& file, OwnPtr<DocumentData>&& data)
 {
     m_documents.set(filedb().to_absolute_path(file), move(data));
 }
 
-ShellComprehensionEngine::DocumentData::DocumentData(DeprecatedString&& _text, DeprecatedString _filename)
+ShellComprehensionEngine::DocumentData::DocumentData(ByteString&& _text, ByteString _filename)
     : filename(move(_filename))
     , text(move(_text))
     , node(parse())
 {
 }
 
-Vector<DeprecatedString> const& ShellComprehensionEngine::DocumentData::sourced_paths() const
+Vector<ByteString> const& ShellComprehensionEngine::DocumentData::sourced_paths() const
 {
     if (all_sourced_paths.has_value())
         return all_sourced_paths.value();
@@ -82,19 +82,19 @@ Vector<DeprecatedString> const& ShellComprehensionEngine::DocumentData::sourced_
                         auto name_list = name_list_node->resolve_as_list(nullptr).release_value_but_fixme_should_propagate_errors();
                         StringBuilder builder;
                         builder.join(' ', name_list);
-                        sourced_files.set(builder.to_deprecated_string());
+                        sourced_files.set(builder.to_byte_string());
                     }
                 }
             }
             ::Shell::AST::NodeVisitor::visit(node);
         }
 
-        HashTable<DeprecatedString> sourced_files;
+        HashTable<ByteString> sourced_files;
     } visitor;
 
     node->visit(visitor);
 
-    Vector<DeprecatedString> sourced_paths;
+    Vector<ByteString> sourced_paths;
     for (auto& entry : visitor.sourced_files)
         sourced_paths.append(move(entry));
 
@@ -134,7 +134,7 @@ size_t ShellComprehensionEngine::resolve(ShellComprehensionEngine::DocumentData
     return offset;
 }
 
-Vector<CodeComprehension::AutocompleteResultEntry> ShellComprehensionEngine::get_suggestions(DeprecatedString const& file, const GUI::TextPosition& position)
+Vector<CodeComprehension::AutocompleteResultEntry> ShellComprehensionEngine::get_suggestions(ByteString const& file, const GUI::TextPosition& position)
 {
     dbgln_if(SH_LANGUAGE_SERVER_DEBUG, "ShellComprehensionEngine position {}:{}", position.line(), position.column());
 
@@ -155,17 +155,17 @@ Vector<CodeComprehension::AutocompleteResultEntry> ShellComprehensionEngine::get
     return entries;
 }
 
-void ShellComprehensionEngine::on_edit(DeprecatedString const& file)
+void ShellComprehensionEngine::on_edit(ByteString const& file)
 {
     set_document_data(file, create_document_data_for(file));
 }
 
-void ShellComprehensionEngine::file_opened([[maybe_unused]] DeprecatedString const& file)
+void ShellComprehensionEngine::file_opened([[maybe_unused]] ByteString const& file)
 {
     set_document_data(file, create_document_data_for(file));
 }
 
-Optional<CodeComprehension::ProjectLocation> ShellComprehensionEngine::find_declaration_of(DeprecatedString const& filename, const GUI::TextPosition& identifier_position)
+Optional<CodeComprehension::ProjectLocation> ShellComprehensionEngine::find_declaration_of(ByteString const& filename, const GUI::TextPosition& identifier_position)
 {
     dbgln_if(SH_LANGUAGE_SERVER_DEBUG, "find_declaration_of({}, {}:{})", filename, identifier_position.line(), identifier_position.column());
     auto const& document = get_or_create_document_data(filename);
@@ -196,7 +196,7 @@ Optional<CodeComprehension::ProjectLocation> ShellComprehensionEngine::find_decl
 void ShellComprehensionEngine::update_declared_symbols(DocumentData const& document)
 {
     struct Visitor : public ::Shell::AST::NodeVisitor {
-        explicit Visitor(DeprecatedString const& filename)
+        explicit Visitor(ByteString const& filename)
             : filename(filename)
         {
         }
@@ -208,9 +208,9 @@ void ShellComprehensionEngine::update_declared_symbols(DocumentData const& docum
                 if (!literal)
                     continue;
 
-                DeprecatedString name;
+                ByteString name;
                 if (literal->is_bareword())
-                    name = static_ptr_cast<::Shell::AST::BarewordLiteral const>(literal)->text().to_deprecated_string();
+                    name = static_ptr_cast<::Shell::AST::BarewordLiteral const>(literal)->text().to_byte_string();
 
                 if (!name.is_empty()) {
                     dbgln("Found variable {}", name);
@@ -223,10 +223,10 @@ void ShellComprehensionEngine::update_declared_symbols(DocumentData const& docum
         void visit(::Shell::AST::FunctionDeclaration const* node) override
         {
             dbgln("Found function {}", node->name().name);
-            declarations.append({ node->name().name.to_deprecated_string(), { filename, node->position().start_line.line_number, node->position().start_line.line_column }, CodeComprehension::DeclarationType::Function, {} });
+            declarations.append({ node->name().name.to_byte_string(), { filename, node->position().start_line.line_number, node->position().start_line.line_column }, CodeComprehension::DeclarationType::Function, {} });
         }
 
-        DeprecatedString const& filename;
+        ByteString const& filename;
         Vector<CodeComprehension::Declaration> declarations;
     } visitor { document.filename };
 
diff --git a/Userland/Libraries/LibCodeComprehension/Shell/ShellComprehensionEngine.h b/Userland/Libraries/LibCodeComprehension/Shell/ShellComprehensionEngine.h
index 5b36c1b082a..9de44b24cd8 100644
--- a/Userland/Libraries/LibCodeComprehension/Shell/ShellComprehensionEngine.h
+++ b/Userland/Libraries/LibCodeComprehension/Shell/ShellComprehensionEngine.h
@@ -14,31 +14,31 @@ namespace CodeComprehension::Shell {
 class ShellComprehensionEngine : public CodeComprehensionEngine {
 public:
     ShellComprehensionEngine(FileDB const& filedb);
-    virtual Vector<CodeComprehension::AutocompleteResultEntry> get_suggestions(DeprecatedString const& file, const GUI::TextPosition& position) override;
-    virtual void on_edit(DeprecatedString const& file) override;
-    virtual void file_opened([[maybe_unused]] DeprecatedString const& file) override;
-    virtual Optional<CodeComprehension::ProjectLocation> find_declaration_of(DeprecatedString const& filename, const GUI::TextPosition& identifier_position) override;
+    virtual Vector<CodeComprehension::AutocompleteResultEntry> get_suggestions(ByteString const& file, const GUI::TextPosition& position) override;
+    virtual void on_edit(ByteString const& file) override;
+    virtual void file_opened([[maybe_unused]] ByteString const& file) override;
+    virtual Optional<CodeComprehension::ProjectLocation> find_declaration_of(ByteString const& filename, const GUI::TextPosition& identifier_position) override;
 
 private:
     struct DocumentData {
-        DocumentData(DeprecatedString&& text, DeprecatedString filename);
-        DeprecatedString filename;
-        DeprecatedString text;
+        DocumentData(ByteString&& text, ByteString filename);
+        ByteString filename;
+        ByteString text;
         NonnullRefPtr<::Shell::AST::Node> node;
 
-        Vector<DeprecatedString> const& sourced_paths() const;
+        Vector<ByteString> const& sourced_paths() const;
 
     private:
         NonnullRefPtr<::Shell::AST::Node> parse() const;
 
-        mutable Optional<Vector<DeprecatedString>> all_sourced_paths {};
+        mutable Optional<Vector<ByteString>> all_sourced_paths {};
     };
 
-    DocumentData const& get_document_data(DeprecatedString const& file) const;
-    DocumentData const& get_or_create_document_data(DeprecatedString const& file);
-    void set_document_data(DeprecatedString const& file, OwnPtr<DocumentData>&& data);
+    DocumentData const& get_document_data(ByteString const& file) const;
+    DocumentData const& get_or_create_document_data(ByteString const& file);
+    void set_document_data(ByteString const& file, OwnPtr<DocumentData>&& data);
 
-    OwnPtr<DocumentData> create_document_data_for(DeprecatedString const& file);
+    OwnPtr<DocumentData> create_document_data_for(ByteString const& file);
     void update_declared_symbols(DocumentData const&);
 
     static size_t resolve(ShellComprehensionEngine::DocumentData const& document, const GUI::TextPosition& position);
@@ -51,7 +51,7 @@ private:
         return *s_shell;
     }
 
-    HashMap<DeprecatedString, OwnPtr<DocumentData>> m_documents;
+    HashMap<ByteString, OwnPtr<DocumentData>> m_documents;
     static RefPtr<::Shell::Shell> s_shell;
 };
 }
diff --git a/Userland/Libraries/LibCodeComprehension/Types.h b/Userland/Libraries/LibCodeComprehension/Types.h
index d5943cd28b6..68ee592a675 100644
--- a/Userland/Libraries/LibCodeComprehension/Types.h
+++ b/Userland/Libraries/LibCodeComprehension/Types.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 
 namespace CodeComprehension {
 
@@ -16,11 +16,11 @@ enum class Language {
 };
 
 struct AutocompleteResultEntry {
-    DeprecatedString completion;
+    ByteString completion;
     size_t partial_input_length { 0 };
     // TODO: Actually assign the value of this field in more places (when applicable).
     Language language { Language::Unspecified };
-    DeprecatedString display_text {};
+    ByteString display_text {};
 
     enum class HideAutocompleteAfterApplying {
         No,
@@ -30,7 +30,7 @@ struct AutocompleteResultEntry {
 };
 
 struct ProjectLocation {
-    DeprecatedString file;
+    ByteString file;
     size_t line { 0 };
     size_t column { 0 };
 
@@ -51,10 +51,10 @@ enum class DeclarationType {
 };
 
 struct Declaration {
-    DeprecatedString name;
+    ByteString name;
     ProjectLocation position;
     DeclarationType type;
-    DeprecatedString scope;
+    ByteString scope;
 
     bool operator==(Declaration const& other) const
     {
@@ -109,8 +109,8 @@ struct TokenInfo {
 };
 
 struct TodoEntry {
-    DeprecatedString content;
-    DeprecatedString filename;
+    ByteString content;
+    ByteString filename;
     size_t line { 0 };
     size_t column { 0 };
 };
diff --git a/Userland/Libraries/LibConfig/Client.cpp b/Userland/Libraries/LibConfig/Client.cpp
index 4de308853b3..e01141dce66 100644
--- a/Userland/Libraries/LibConfig/Client.cpp
+++ b/Userland/Libraries/LibConfig/Client.cpp
@@ -19,27 +19,27 @@ Client& Client::the()
     return *s_the;
 }
 
-void Client::pledge_domains(Vector<DeprecatedString> const& domains)
+void Client::pledge_domains(Vector<ByteString> const& domains)
 {
     async_pledge_domains(domains);
 }
 
-void Client::monitor_domain(DeprecatedString const& domain)
+void Client::monitor_domain(ByteString const& domain)
 {
     async_monitor_domain(domain);
 }
 
-Vector<DeprecatedString> Client::list_keys(StringView domain, StringView group)
+Vector<ByteString> Client::list_keys(StringView domain, StringView group)
 {
     return list_config_keys(domain, group);
 }
 
-Vector<DeprecatedString> Client::list_groups(StringView domain)
+Vector<ByteString> Client::list_groups(StringView domain)
 {
     return list_config_groups(domain);
 }
 
-DeprecatedString Client::read_string(StringView domain, StringView group, StringView key, StringView fallback)
+ByteString Client::read_string(StringView domain, StringView group, StringView key, StringView fallback)
 {
     return read_string_value(domain, group, key).value_or(fallback);
 }
@@ -94,49 +94,49 @@ void Client::add_group(StringView domain, StringView group)
     add_group_entry(domain, group);
 }
 
-void Client::notify_changed_string_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, DeprecatedString const& value)
+void Client::notify_changed_string_value(ByteString const& domain, ByteString const& group, ByteString const& key, ByteString const& value)
 {
     Listener::for_each([&](auto& listener) {
         listener.config_string_did_change(domain, group, key, value);
     });
 }
 
-void Client::notify_changed_i32_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, i32 value)
+void Client::notify_changed_i32_value(ByteString const& domain, ByteString const& group, ByteString const& key, i32 value)
 {
     Listener::for_each([&](auto& listener) {
         listener.config_i32_did_change(domain, group, key, value);
     });
 }
 
-void Client::notify_changed_u32_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, u32 value)
+void Client::notify_changed_u32_value(ByteString const& domain, ByteString const& group, ByteString const& key, u32 value)
 {
     Listener::for_each([&](auto& listener) {
         listener.config_u32_did_change(domain, group, key, value);
     });
 }
 
-void Client::notify_changed_bool_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, bool value)
+void Client::notify_changed_bool_value(ByteString const& domain, ByteString const& group, ByteString const& key, bool value)
 {
     Listener::for_each([&](auto& listener) {
         listener.config_bool_did_change(domain, group, key, value);
     });
 }
 
-void Client::notify_removed_key(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key)
+void Client::notify_removed_key(ByteString const& domain, ByteString const& group, ByteString const& key)
 {
     Listener::for_each([&](auto& listener) {
         listener.config_key_was_removed(domain, group, key);
     });
 }
 
-void Client::notify_removed_group(DeprecatedString const& domain, DeprecatedString const& group)
+void Client::notify_removed_group(ByteString const& domain, ByteString const& group)
 {
     Listener::for_each([&](auto& listener) {
         listener.config_group_was_removed(domain, group);
     });
 }
 
-void Client::notify_added_group(DeprecatedString const& domain, DeprecatedString const& group)
+void Client::notify_added_group(ByteString const& domain, ByteString const& group)
 {
     Listener::for_each([&](auto& listener) {
         listener.config_group_was_added(domain, group);
diff --git a/Userland/Libraries/LibConfig/Client.h b/Userland/Libraries/LibConfig/Client.h
index 0da1805894e..601188c80d3 100644
--- a/Userland/Libraries/LibConfig/Client.h
+++ b/Userland/Libraries/LibConfig/Client.h
@@ -20,13 +20,13 @@ class Client final
     IPC_CLIENT_CONNECTION(Client, "/tmp/session/%sid/portal/config"sv)
 
 public:
-    void pledge_domains(Vector<DeprecatedString> const&);
-    void monitor_domain(DeprecatedString const&);
+    void pledge_domains(Vector<ByteString> const&);
+    void monitor_domain(ByteString const&);
 
-    Vector<DeprecatedString> list_groups(StringView domain);
-    Vector<DeprecatedString> list_keys(StringView domain, StringView group);
+    Vector<ByteString> list_groups(StringView domain);
+    Vector<ByteString> list_keys(StringView domain, StringView group);
 
-    DeprecatedString read_string(StringView domain, StringView group, StringView key, StringView fallback);
+    ByteString read_string(StringView domain, StringView group, StringView key, StringView fallback);
     i32 read_i32(StringView domain, StringView group, StringView key, i32 fallback);
     u32 read_u32(StringView domain, StringView group, StringView key, u32 fallback);
     bool read_bool(StringView domain, StringView group, StringView key, bool fallback);
@@ -47,26 +47,26 @@ private:
     {
     }
 
-    void notify_changed_string_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, DeprecatedString const& value) override;
-    void notify_changed_i32_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, i32 value) override;
-    void notify_changed_u32_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, u32 value) override;
-    void notify_changed_bool_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, bool value) override;
-    void notify_removed_key(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key) override;
-    void notify_removed_group(DeprecatedString const& domain, DeprecatedString const& group) override;
-    void notify_added_group(DeprecatedString const& domain, DeprecatedString const& group) override;
+    void notify_changed_string_value(ByteString const& domain, ByteString const& group, ByteString const& key, ByteString const& value) override;
+    void notify_changed_i32_value(ByteString const& domain, ByteString const& group, ByteString const& key, i32 value) override;
+    void notify_changed_u32_value(ByteString const& domain, ByteString const& group, ByteString const& key, u32 value) override;
+    void notify_changed_bool_value(ByteString const& domain, ByteString const& group, ByteString const& key, bool value) override;
+    void notify_removed_key(ByteString const& domain, ByteString const& group, ByteString const& key) override;
+    void notify_removed_group(ByteString const& domain, ByteString const& group) override;
+    void notify_added_group(ByteString const& domain, ByteString const& group) override;
 };
 
-inline Vector<DeprecatedString> list_groups(StringView domain)
+inline Vector<ByteString> list_groups(StringView domain)
 {
     return Client::the().list_groups(domain);
 }
 
-inline Vector<DeprecatedString> list_keys(StringView domain, StringView group)
+inline Vector<ByteString> list_keys(StringView domain, StringView group)
 {
     return Client::the().list_keys(domain, group);
 }
 
-inline DeprecatedString read_string(StringView domain, StringView group, StringView key, StringView fallback = {})
+inline ByteString read_string(StringView domain, StringView group, StringView key, StringView fallback = {})
 {
     return Client::the().read_string(domain, group, key, fallback);
 }
@@ -121,17 +121,17 @@ inline void add_group(StringView domain, StringView group)
     Client::the().add_group(domain, group);
 }
 
-inline void pledge_domains(Vector<DeprecatedString> const& domains)
+inline void pledge_domains(Vector<ByteString> const& domains)
 {
     Client::the().pledge_domains(domains);
 }
 
-inline void pledge_domain(DeprecatedString const& domain)
+inline void pledge_domain(ByteString const& domain)
 {
     Client::the().pledge_domains({ domain });
 }
 
-inline void monitor_domain(DeprecatedString const& domain)
+inline void monitor_domain(ByteString const& domain)
 {
     Client::the().monitor_domain(domain);
 }
diff --git a/Userland/Libraries/LibConfig/Listener.cpp b/Userland/Libraries/LibConfig/Listener.cpp
index 170aa6c536a..cb95fc95a6e 100644
--- a/Userland/Libraries/LibConfig/Listener.cpp
+++ b/Userland/Libraries/LibConfig/Listener.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashTable.h>
 #include <LibConfig/Listener.h>
diff --git a/Userland/Libraries/LibCore/Account.cpp b/Userland/Libraries/LibCore/Account.cpp
index 031524c421d..40a9fccf468 100644
--- a/Userland/Libraries/LibCore/Account.cpp
+++ b/Userland/Libraries/LibCore/Account.cpp
@@ -27,7 +27,7 @@
 
 namespace Core {
 
-static DeprecatedString get_salt()
+static ByteString get_salt()
 {
     char random_data[12];
     fill_with_random({ random_data, sizeof(random_data) });
@@ -39,7 +39,7 @@ static DeprecatedString get_salt()
     auto salt_string = MUST(encode_base64({ random_data, sizeof(random_data) }));
     builder.append(salt_string);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 static Vector<gid_t> get_extra_gids(passwd const& pwd)
@@ -191,25 +191,25 @@ void Account::set_password(SecretString const& password)
 
 void Account::set_password_enabled(bool enabled)
 {
-    auto flattened_password_hash = m_password_hash.value_or(DeprecatedString::empty());
+    auto flattened_password_hash = m_password_hash.value_or(ByteString::empty());
     if (enabled && !flattened_password_hash.is_empty() && flattened_password_hash[0] == '!') {
         m_password_hash = flattened_password_hash.substring(1, flattened_password_hash.length() - 1);
     } else if (!enabled && (flattened_password_hash.is_empty() || flattened_password_hash[0] != '!')) {
         StringBuilder builder;
         builder.append('!');
         builder.append(flattened_password_hash);
-        m_password_hash = builder.to_deprecated_string();
+        m_password_hash = builder.to_byte_string();
     }
 }
 
 void Account::delete_password()
 {
-    m_password_hash = DeprecatedString::empty();
+    m_password_hash = ByteString::empty();
 }
 
 Account::Account(passwd const& pwd, spwd const& spwd, Vector<gid_t> extra_gids)
     : m_username(pwd.pw_name)
-    , m_password_hash(spwd.sp_pwdp ? Optional<DeprecatedString>(spwd.sp_pwdp) : OptionalNone {})
+    , m_password_hash(spwd.sp_pwdp ? Optional<ByteString>(spwd.sp_pwdp) : OptionalNone {})
     , m_uid(pwd.pw_uid)
     , m_gid(pwd.pw_gid)
     , m_gecos(pwd.pw_gecos)
@@ -219,7 +219,7 @@ Account::Account(passwd const& pwd, spwd const& spwd, Vector<gid_t> extra_gids)
 {
 }
 
-ErrorOr<DeprecatedString> Account::generate_passwd_file() const
+ErrorOr<ByteString> Account::generate_passwd_file() const
 {
     StringBuilder builder;
     char buffer[1024] = { 0 };
@@ -250,10 +250,10 @@ ErrorOr<DeprecatedString> Account::generate_passwd_file() const
         }
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-ErrorOr<DeprecatedString> Account::generate_group_file() const
+ErrorOr<ByteString> Account::generate_group_file() const
 {
     StringBuilder builder;
     char buffer[1024] = { 0 };
@@ -283,14 +283,14 @@ ErrorOr<DeprecatedString> Account::generate_group_file() const
         if (should_be_present && !already_present)
             members.append(m_username.characters());
 
-        builder.appendff("{}:{}:{}:{}\n", group->gr_name, group->gr_passwd, group->gr_gid, DeprecatedString::join(","sv, members));
+        builder.appendff("{}:{}:{}:{}\n", group->gr_name, group->gr_passwd, group->gr_gid, ByteString::join(","sv, members));
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 #ifndef AK_OS_BSD_GENERIC
-ErrorOr<DeprecatedString> Account::generate_shadow_file() const
+ErrorOr<ByteString> Account::generate_shadow_file() const
 {
     StringBuilder builder;
 
@@ -302,25 +302,25 @@ ErrorOr<DeprecatedString> Account::generate_shadow_file() const
         if (p->sp_namp == m_username) {
             if (m_deleted)
                 continue;
-            builder.appendff("{}:{}", m_username, m_password_hash.value_or(DeprecatedString::empty()));
+            builder.appendff("{}:{}", m_username, m_password_hash.value_or(ByteString::empty()));
         } else
             builder.appendff("{}:{}", p->sp_namp, p->sp_pwdp);
 
         builder.appendff(":{}:{}:{}:{}:{}:{}:{}\n",
-            (p->sp_lstchg == -1) ? "" : DeprecatedString::formatted("{}", p->sp_lstchg),
-            (p->sp_min == -1) ? "" : DeprecatedString::formatted("{}", p->sp_min),
-            (p->sp_max == -1) ? "" : DeprecatedString::formatted("{}", p->sp_max),
-            (p->sp_warn == -1) ? "" : DeprecatedString::formatted("{}", p->sp_warn),
-            (p->sp_inact == -1) ? "" : DeprecatedString::formatted("{}", p->sp_inact),
-            (p->sp_expire == -1) ? "" : DeprecatedString::formatted("{}", p->sp_expire),
-            (p->sp_flag == 0) ? "" : DeprecatedString::formatted("{}", p->sp_flag));
+            (p->sp_lstchg == -1) ? "" : ByteString::formatted("{}", p->sp_lstchg),
+            (p->sp_min == -1) ? "" : ByteString::formatted("{}", p->sp_min),
+            (p->sp_max == -1) ? "" : ByteString::formatted("{}", p->sp_max),
+            (p->sp_warn == -1) ? "" : ByteString::formatted("{}", p->sp_warn),
+            (p->sp_inact == -1) ? "" : ByteString::formatted("{}", p->sp_inact),
+            (p->sp_expire == -1) ? "" : ByteString::formatted("{}", p->sp_expire),
+            (p->sp_flag == 0) ? "" : ByteString::formatted("{}", p->sp_flag));
     }
     endspent();
 
     if (errno)
         return Error::from_errno(errno);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 #endif
 
diff --git a/Userland/Libraries/LibCore/Account.h b/Userland/Libraries/LibCore/Account.h
index c371ff4fa93..b176a443819 100644
--- a/Userland/Libraries/LibCore/Account.h
+++ b/Userland/Libraries/LibCore/Account.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Types.h>
 #include <AK/Vector.h>
 #include <LibCore/SecretString.h>
@@ -40,8 +40,8 @@ public:
     bool authenticate(SecretString const& password) const;
     ErrorOr<void> login() const;
 
-    DeprecatedString username() const { return m_username; }
-    DeprecatedString password_hash() const { return m_password_hash.value_or(DeprecatedString::empty()); }
+    ByteString username() const { return m_username; }
+    ByteString password_hash() const { return m_password_hash.value_or(ByteString::empty()); }
 
     // Setters only affect in-memory copy of password.
     // You must call sync to apply changes.
@@ -62,9 +62,9 @@ public:
 
     uid_t uid() const { return m_uid; }
     gid_t gid() const { return m_gid; }
-    DeprecatedString const& gecos() const { return m_gecos; }
-    DeprecatedString const& home_directory() const { return m_home_directory; }
-    DeprecatedString const& shell() const { return m_shell; }
+    ByteString const& gecos() const { return m_gecos; }
+    ByteString const& home_directory() const { return m_home_directory; }
+    ByteString const& shell() const { return m_shell; }
     Vector<gid_t> const& extra_gids() const { return m_extra_gids; }
 
     ErrorOr<void> sync();
@@ -74,20 +74,20 @@ private:
 
     Account(passwd const& pwd, spwd const& spwd, Vector<gid_t> extra_gids);
 
-    ErrorOr<DeprecatedString> generate_passwd_file() const;
-    ErrorOr<DeprecatedString> generate_group_file() const;
+    ErrorOr<ByteString> generate_passwd_file() const;
+    ErrorOr<ByteString> generate_group_file() const;
 #ifndef AK_OS_BSD_GENERIC
-    ErrorOr<DeprecatedString> generate_shadow_file() const;
+    ErrorOr<ByteString> generate_shadow_file() const;
 #endif
 
-    DeprecatedString m_username;
+    ByteString m_username;
 
-    Optional<DeprecatedString> m_password_hash;
+    Optional<ByteString> m_password_hash;
     uid_t m_uid { 0 };
     gid_t m_gid { 0 };
-    DeprecatedString m_gecos;
-    DeprecatedString m_home_directory;
-    DeprecatedString m_shell;
+    ByteString m_gecos;
+    ByteString m_home_directory;
+    ByteString m_shell;
     Vector<gid_t> m_extra_gids;
     bool m_deleted { false };
 };
diff --git a/Userland/Libraries/LibCore/ArgsParser.cpp b/Userland/Libraries/LibCore/ArgsParser.cpp
index ec94fd0f366..bf51e8ae0ba 100644
--- a/Userland/Libraries/LibCore/ArgsParser.cpp
+++ b/Userland/Libraries/LibCore/ArgsParser.cpp
@@ -88,7 +88,7 @@ bool ArgsParser::parse(Span<StringView> arguments, FailureBehavior failure_behav
         }
     }
 
-    auto short_options = short_options_builder.to_deprecated_string();
+    auto short_options = short_options_builder.to_byte_string();
     size_t option_index = 1;
     while (true) {
         auto result = parser.getopt(arguments.slice(1), short_options, long_options, {});
@@ -439,7 +439,7 @@ void ArgsParser::add_option(bool& value, char const* help_string, char const* lo
     add_option(move(option));
 }
 
-void ArgsParser::add_option(DeprecatedString& value, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode)
+void ArgsParser::add_option(ByteString& value, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode)
 {
     Option option {
         OptionArgumentMode::Required,
@@ -599,7 +599,7 @@ void ArgsParser::add_option(Vector<size_t>& values, char const* help_string, cha
     add_option(move(option));
 }
 
-void ArgsParser::add_option(Vector<DeprecatedString>& values, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode)
+void ArgsParser::add_option(Vector<ByteString>& values, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode)
 {
     Option option {
         OptionArgumentMode::Optional,
@@ -622,7 +622,7 @@ void ArgsParser::add_positional_argument(Arg&& arg)
     m_positional_args.append(move(arg));
 }
 
-void ArgsParser::add_positional_argument(DeprecatedString& value, char const* help_string, char const* name, Required required)
+void ArgsParser::add_positional_argument(ByteString& value, char const* help_string, char const* name, Required required)
 {
     Arg arg {
         help_string,
@@ -713,7 +713,7 @@ void ArgsParser::add_positional_argument(double& value, char const* help_string,
     add_positional_argument(move(arg));
 }
 
-void ArgsParser::add_positional_argument(Vector<DeprecatedString>& values, char const* help_string, char const* name, Required required)
+void ArgsParser::add_positional_argument(Vector<ByteString>& values, char const* help_string, char const* name, Required required)
 {
     Arg arg {
         help_string,
@@ -837,12 +837,12 @@ void ArgsParser::autocomplete(FILE* file, StringView program_name, ReadonlySpan<
 
     auto write_completion = [&](auto format, auto& option, auto has_invariant, auto... args) {
         JsonObject object;
-        object.set("completion", DeprecatedString::formatted(StringView { format, strlen(format) }, args...));
+        object.set("completion", ByteString::formatted(StringView { format, strlen(format) }, args...));
         object.set("static_offset", 0);
         object.set("invariant_offset", has_invariant ? option_to_complete.length() : 0u);
         object.set("display_trivia", option.help_string);
         object.set("trailing_trivia", option.argument_mode == OptionArgumentMode::Required ? " " : "");
-        outln(file, "{}", object.to_deprecated_string());
+        outln(file, "{}", object.to_byte_string());
     };
 
     if (option_to_complete.starts_with("--"sv)) {
diff --git a/Userland/Libraries/LibCore/ArgsParser.h b/Userland/Libraries/LibCore/ArgsParser.h
index 9b42e943752..254fa317ed3 100644
--- a/Userland/Libraries/LibCore/ArgsParser.h
+++ b/Userland/Libraries/LibCore/ArgsParser.h
@@ -6,8 +6,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/Concepts.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Function.h>
 #include <AK/Vector.h>
 #include <LibMain/Main.h>
@@ -54,11 +54,11 @@ public:
         Function<ErrorOr<bool>(StringView)> accept_value;
         OptionHideMode hide_mode { OptionHideMode::None };
 
-        DeprecatedString name_for_display() const
+        ByteString name_for_display() const
         {
             if (long_name)
-                return DeprecatedString::formatted("--{}", long_name);
-            return DeprecatedString::formatted("-{:c}", short_name);
+                return ByteString::formatted("--{}", long_name);
+            return ByteString::formatted("-{:c}", short_name);
         }
     };
 
@@ -101,7 +101,7 @@ public:
             },
             .hide_mode = hide_mode });
     }
-    void add_option(DeprecatedString& value, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode = OptionHideMode::None);
+    void add_option(ByteString& value, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode = OptionHideMode::None);
     void add_option(String& value, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode = OptionHideMode::None);
     void add_option(StringView& value, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode = OptionHideMode::None);
     template<Integral I>
@@ -112,16 +112,16 @@ public:
     void add_option(Vector<size_t>& values, char const* help_string, char const* long_name, char short_name, char const* value_name, char separator = ',', OptionHideMode hide_mode = OptionHideMode::None);
     // Note: This option is being used when we expect the user to use the same option
     // multiple times (e.g. "program --option=example --option=anotherexample ...").
-    void add_option(Vector<DeprecatedString>& values, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode = OptionHideMode::None);
+    void add_option(Vector<ByteString>& values, char const* help_string, char const* long_name, char short_name, char const* value_name, OptionHideMode hide_mode = OptionHideMode::None);
 
     void add_positional_argument(Arg&&);
-    void add_positional_argument(DeprecatedString& value, char const* help_string, char const* name, Required required = Required::Yes);
+    void add_positional_argument(ByteString& value, char const* help_string, char const* name, Required required = Required::Yes);
     void add_positional_argument(StringView& value, char const* help_string, char const* name, Required required = Required::Yes);
     void add_positional_argument(String& value, char const* help_string, char const* name, Required required = Required::Yes);
     template<Integral I>
     void add_positional_argument(I& value, char const* help_string, char const* name, Required required = Required::Yes);
     void add_positional_argument(double& value, char const* help_string, char const* name, Required required = Required::Yes);
-    void add_positional_argument(Vector<DeprecatedString>& value, char const* help_string, char const* name, Required required = Required::Yes);
+    void add_positional_argument(Vector<ByteString>& value, char const* help_string, char const* name, Required required = Required::Yes);
     void add_positional_argument(Vector<StringView>& value, char const* help_string, char const* name, Required required = Required::Yes);
     void add_positional_argument(Vector<String>& value, char const* help_string, char const* name, Required required = Required::Yes);
 
diff --git a/Userland/Libraries/LibCore/Command.cpp b/Userland/Libraries/LibCore/Command.cpp
index 2e6420c595e..86505babd51 100644
--- a/Userland/Libraries/LibCore/Command.cpp
+++ b/Userland/Libraries/LibCore/Command.cpp
@@ -63,7 +63,7 @@ ErrorOr<void> Command::write(StringView input)
     return {};
 }
 
-ErrorOr<void> Command::write_lines(Span<DeprecatedString> lines)
+ErrorOr<void> Command::write_lines(Span<ByteString> lines)
 {
     // It's possible the process dies before we can write everything to the
     // stdin. So make sure that we don't crash but just stop writing.
@@ -83,8 +83,8 @@ ErrorOr<void> Command::write_lines(Span<DeprecatedString> lines)
             perror("sigaction");
     });
 
-    for (DeprecatedString const& line : lines)
-        TRY(m_stdin->write_until_depleted(DeprecatedString::formatted("{}\n", line).bytes()));
+    for (ByteString const& line : lines)
+        TRY(m_stdin->write_until_depleted(ByteString::formatted("{}\n", line).bytes()));
 
     return {};
 }
@@ -120,7 +120,7 @@ ErrorOr<Command::ProcessResult> Command::status(int options)
 // Only supported in serenity mode because we use `posix_spawn_file_actions_addchdir`
 #ifdef AK_OS_SERENITY
 
-ErrorOr<CommandResult> command(DeprecatedString const& command_string, Optional<LexicalPath> chdir)
+ErrorOr<CommandResult> command(ByteString const& command_string, Optional<LexicalPath> chdir)
 {
     auto parts = command_string.split(' ');
     if (parts.is_empty())
@@ -130,7 +130,7 @@ ErrorOr<CommandResult> command(DeprecatedString const& command_string, Optional<
     return command(program, parts, chdir);
 }
 
-ErrorOr<CommandResult> command(DeprecatedString const& program, Vector<DeprecatedString> const& arguments, Optional<LexicalPath> chdir)
+ErrorOr<CommandResult> command(ByteString const& program, Vector<ByteString> const& arguments, Optional<LexicalPath> chdir)
 {
     int stdout_pipe[2] = {};
     int stderr_pipe[2] = {};
diff --git a/Userland/Libraries/LibCore/Command.h b/Userland/Libraries/LibCore/Command.h
index 88ba2d43791..e136310aa44 100644
--- a/Userland/Libraries/LibCore/Command.h
+++ b/Userland/Libraries/LibCore/Command.h
@@ -25,8 +25,8 @@ struct CommandResult {
     ByteBuffer error;
 };
 
-ErrorOr<CommandResult> command(DeprecatedString const& program, Vector<DeprecatedString> const& arguments, Optional<LexicalPath> chdir);
-ErrorOr<CommandResult> command(DeprecatedString const& command_string, Optional<LexicalPath> chdir);
+ErrorOr<CommandResult> command(ByteString const& program, Vector<ByteString> const& arguments, Optional<LexicalPath> chdir);
+ErrorOr<CommandResult> command(ByteString const& command_string, Optional<LexicalPath> chdir);
 
 class Command {
 public:
@@ -41,7 +41,7 @@ public:
 
     ErrorOr<void> write(StringView input);
 
-    ErrorOr<void> write_lines(Span<DeprecatedString> lines);
+    ErrorOr<void> write_lines(Span<ByteString> lines);
 
     ErrorOr<ProcessOutputs> read_all();
 
diff --git a/Userland/Libraries/LibCore/ConfigFile.cpp b/Userland/Libraries/LibCore/ConfigFile.cpp
index 8e392898bae..6951cbf6939 100644
--- a/Userland/Libraries/LibCore/ConfigFile.cpp
+++ b/Userland/Libraries/LibCore/ConfigFile.cpp
@@ -17,28 +17,28 @@
 
 namespace Core {
 
-ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open_for_lib(DeprecatedString const& lib_name, AllowWriting allow_altering)
+ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open_for_lib(ByteString const& lib_name, AllowWriting allow_altering)
 {
-    DeprecatedString directory_name = DeprecatedString::formatted("{}/lib", StandardPaths::config_directory());
+    ByteString directory_name = ByteString::formatted("{}/lib", StandardPaths::config_directory());
     auto directory = TRY(Directory::create(directory_name, Directory::CreateDirectories::Yes));
-    auto path = DeprecatedString::formatted("{}/{}.ini", directory, lib_name);
+    auto path = ByteString::formatted("{}/{}.ini", directory, lib_name);
     return ConfigFile::open(path, allow_altering);
 }
 
-ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open_for_app(DeprecatedString const& app_name, AllowWriting allow_altering)
+ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open_for_app(ByteString const& app_name, AllowWriting allow_altering)
 {
     auto directory = TRY(Directory::create(StandardPaths::config_directory(), Directory::CreateDirectories::Yes));
-    auto path = DeprecatedString::formatted("{}/{}.ini", directory, app_name);
+    auto path = ByteString::formatted("{}/{}.ini", directory, app_name);
     return ConfigFile::open(path, allow_altering);
 }
 
-ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open_for_system(DeprecatedString const& app_name, AllowWriting allow_altering)
+ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open_for_system(ByteString const& app_name, AllowWriting allow_altering)
 {
-    auto path = DeprecatedString::formatted("/etc/{}.ini", app_name);
+    auto path = ByteString::formatted("/etc/{}.ini", app_name);
     return ConfigFile::open(path, allow_altering);
 }
 
-ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open(DeprecatedString const& filename, AllowWriting allow_altering)
+ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open(ByteString const& filename, AllowWriting allow_altering)
 {
     auto maybe_file = File::open(filename, allow_altering == AllowWriting::Yes ? File::OpenMode::ReadWrite : File::OpenMode::Read);
     OwnPtr<InputBufferedFile> buffered_file;
@@ -57,13 +57,13 @@ ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open(DeprecatedString const& file
     return config_file;
 }
 
-ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open(DeprecatedString const& filename, int fd)
+ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open(ByteString const& filename, int fd)
 {
     auto file = TRY(File::adopt_fd(fd, File::OpenMode::ReadWrite));
     return open(filename, move(file));
 }
 
-ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open(DeprecatedString const& filename, NonnullOwnPtr<Core::File> file)
+ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open(ByteString const& filename, NonnullOwnPtr<Core::File> file)
 {
     auto buffered_file = TRY(InputBufferedFile::create(move(file)));
 
@@ -72,7 +72,7 @@ ErrorOr<NonnullRefPtr<ConfigFile>> ConfigFile::open(DeprecatedString const& file
     return config_file;
 }
 
-ConfigFile::ConfigFile(DeprecatedString const& filename, OwnPtr<InputBufferedFile> open_file)
+ConfigFile::ConfigFile(ByteString const& filename, OwnPtr<InputBufferedFile> open_file)
     : m_filename(filename)
     , m_file(move(open_file))
 {
@@ -89,7 +89,7 @@ ErrorOr<void> ConfigFile::reparse()
     if (!m_file)
         return {};
 
-    HashMap<DeprecatedString, DeprecatedString>* current_group = nullptr;
+    HashMap<ByteString, ByteString>* current_group = nullptr;
 
     auto buffer = TRY(ByteBuffer::create_uninitialized(4096));
     while (TRY(m_file->can_read_line())) {
@@ -113,7 +113,7 @@ ErrorOr<void> ConfigFile::reparse()
                 builder.append(line[i]);
                 ++i;
             }
-            current_group = &m_groups.ensure(builder.to_deprecated_string());
+            current_group = &m_groups.ensure(builder.to_byte_string());
             break;
         }
         default: { // Start of key
@@ -132,15 +132,15 @@ ErrorOr<void> ConfigFile::reparse()
                 // We're not in a group yet, create one with the name ""...
                 current_group = &m_groups.ensure("");
             }
-            auto value_string = value_builder.to_deprecated_string();
-            current_group->set(key_builder.to_deprecated_string(), value_string.trim_whitespace(TrimMode::Right));
+            auto value_string = value_builder.to_byte_string();
+            current_group->set(key_builder.to_byte_string(), value_string.trim_whitespace(TrimMode::Right));
         }
         }
     }
     return {};
 }
 
-Optional<DeprecatedString> ConfigFile::read_entry_optional(const AK::DeprecatedString& group, const AK::DeprecatedString& key) const
+Optional<ByteString> ConfigFile::read_entry_optional(const AK::ByteString& group, const AK::ByteString& key) const
 {
     if (!has_key(group, key))
         return {};
@@ -149,19 +149,19 @@ Optional<DeprecatedString> ConfigFile::read_entry_optional(const AK::DeprecatedS
     return jt->value;
 }
 
-bool ConfigFile::read_bool_entry(DeprecatedString const& group, DeprecatedString const& key, bool default_value) const
+bool ConfigFile::read_bool_entry(ByteString const& group, ByteString const& key, bool default_value) const
 {
     auto value = read_entry(group, key, default_value ? "true" : "false");
     return value == "1" || value.equals_ignoring_ascii_case("true"sv);
 }
 
-void ConfigFile::write_entry(DeprecatedString const& group, DeprecatedString const& key, DeprecatedString const& value)
+void ConfigFile::write_entry(ByteString const& group, ByteString const& key, ByteString const& value)
 {
     m_groups.ensure(group).ensure(key) = value;
     m_dirty = true;
 }
 
-void ConfigFile::write_bool_entry(DeprecatedString const& group, DeprecatedString const& key, bool value)
+void ConfigFile::write_bool_entry(ByteString const& group, ByteString const& key, bool value)
 {
     write_entry(group, key, value ? "true" : "false");
 }
@@ -178,9 +178,9 @@ ErrorOr<void> ConfigFile::sync()
     TRY(m_file->seek(0, SeekMode::SetPosition));
 
     for (auto& it : m_groups) {
-        TRY(m_file->write_until_depleted(DeprecatedString::formatted("[{}]\n", it.key).bytes()));
+        TRY(m_file->write_until_depleted(ByteString::formatted("[{}]\n", it.key).bytes()));
         for (auto& jt : it.value)
-            TRY(m_file->write_until_depleted(DeprecatedString::formatted("{}={}\n", jt.key, jt.value).bytes()));
+            TRY(m_file->write_until_depleted(ByteString::formatted("{}={}\n", jt.key, jt.value).bytes()));
         TRY(m_file->write_until_depleted("\n"sv.bytes()));
     }
 
@@ -198,12 +198,12 @@ void ConfigFile::dump() const
     }
 }
 
-Vector<DeprecatedString> ConfigFile::groups() const
+Vector<ByteString> ConfigFile::groups() const
 {
     return m_groups.keys();
 }
 
-Vector<DeprecatedString> ConfigFile::keys(DeprecatedString const& group) const
+Vector<ByteString> ConfigFile::keys(ByteString const& group) const
 {
     auto it = m_groups.find(group);
     if (it == m_groups.end())
@@ -211,7 +211,7 @@ Vector<DeprecatedString> ConfigFile::keys(DeprecatedString const& group) const
     return it->value.keys();
 }
 
-bool ConfigFile::has_key(DeprecatedString const& group, DeprecatedString const& key) const
+bool ConfigFile::has_key(ByteString const& group, ByteString const& key) const
 {
     auto it = m_groups.find(group);
     if (it == m_groups.end())
@@ -219,24 +219,24 @@ bool ConfigFile::has_key(DeprecatedString const& group, DeprecatedString const&
     return it->value.contains(key);
 }
 
-bool ConfigFile::has_group(DeprecatedString const& group) const
+bool ConfigFile::has_group(ByteString const& group) const
 {
     return m_groups.contains(group);
 }
 
-void ConfigFile::add_group(DeprecatedString const& group)
+void ConfigFile::add_group(ByteString const& group)
 {
     m_groups.ensure(group);
     m_dirty = true;
 }
 
-void ConfigFile::remove_group(DeprecatedString const& group)
+void ConfigFile::remove_group(ByteString const& group)
 {
     m_groups.remove(group);
     m_dirty = true;
 }
 
-void ConfigFile::remove_entry(DeprecatedString const& group, DeprecatedString const& key)
+void ConfigFile::remove_entry(ByteString const& group, ByteString const& key)
 {
     auto it = m_groups.find(group);
     if (it == m_groups.end())
diff --git a/Userland/Libraries/LibCore/ConfigFile.h b/Userland/Libraries/LibCore/ConfigFile.h
index b2c7a0e8495..a9f054bc60f 100644
--- a/Userland/Libraries/LibCore/ConfigFile.h
+++ b/Userland/Libraries/LibCore/ConfigFile.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
@@ -26,31 +26,31 @@ public:
         No,
     };
 
-    static ErrorOr<NonnullRefPtr<ConfigFile>> open_for_lib(DeprecatedString const& lib_name, AllowWriting = AllowWriting::No);
-    static ErrorOr<NonnullRefPtr<ConfigFile>> open_for_app(DeprecatedString const& app_name, AllowWriting = AllowWriting::No);
-    static ErrorOr<NonnullRefPtr<ConfigFile>> open_for_system(DeprecatedString const& app_name, AllowWriting = AllowWriting::No);
-    static ErrorOr<NonnullRefPtr<ConfigFile>> open(DeprecatedString const& filename, AllowWriting = AllowWriting::No);
-    static ErrorOr<NonnullRefPtr<ConfigFile>> open(DeprecatedString const& filename, int fd);
-    static ErrorOr<NonnullRefPtr<ConfigFile>> open(DeprecatedString const& filename, NonnullOwnPtr<Core::File>);
+    static ErrorOr<NonnullRefPtr<ConfigFile>> open_for_lib(ByteString const& lib_name, AllowWriting = AllowWriting::No);
+    static ErrorOr<NonnullRefPtr<ConfigFile>> open_for_app(ByteString const& app_name, AllowWriting = AllowWriting::No);
+    static ErrorOr<NonnullRefPtr<ConfigFile>> open_for_system(ByteString const& app_name, AllowWriting = AllowWriting::No);
+    static ErrorOr<NonnullRefPtr<ConfigFile>> open(ByteString const& filename, AllowWriting = AllowWriting::No);
+    static ErrorOr<NonnullRefPtr<ConfigFile>> open(ByteString const& filename, int fd);
+    static ErrorOr<NonnullRefPtr<ConfigFile>> open(ByteString const& filename, NonnullOwnPtr<Core::File>);
     ~ConfigFile();
 
-    bool has_group(DeprecatedString const&) const;
-    bool has_key(DeprecatedString const& group, DeprecatedString const& key) const;
+    bool has_group(ByteString const&) const;
+    bool has_key(ByteString const& group, ByteString const& key) const;
 
-    Vector<DeprecatedString> groups() const;
-    Vector<DeprecatedString> keys(DeprecatedString const& group) const;
+    Vector<ByteString> groups() const;
+    Vector<ByteString> keys(ByteString const& group) const;
 
     size_t num_groups() const { return m_groups.size(); }
 
-    DeprecatedString read_entry(DeprecatedString const& group, DeprecatedString const& key, DeprecatedString const& default_value = {}) const
+    ByteString read_entry(ByteString const& group, ByteString const& key, ByteString const& default_value = {}) const
     {
         return read_entry_optional(group, key).value_or(default_value);
     }
-    Optional<DeprecatedString> read_entry_optional(DeprecatedString const& group, DeprecatedString const& key) const;
-    bool read_bool_entry(DeprecatedString const& group, DeprecatedString const& key, bool default_value = false) const;
+    Optional<ByteString> read_entry_optional(ByteString const& group, ByteString const& key) const;
+    bool read_bool_entry(ByteString const& group, ByteString const& key, bool default_value = false) const;
 
     template<Integral T = int>
-    T read_num_entry(DeprecatedString const& group, DeprecatedString const& key, T default_value = 0) const
+    T read_num_entry(ByteString const& group, ByteString const& key, T default_value = 0) const
     {
         if (!has_key(group, key))
             return default_value;
@@ -61,13 +61,13 @@ public:
             return read_entry(group, key, "").to_uint<T>().value_or(default_value);
     }
 
-    void write_entry(DeprecatedString const& group, DeprecatedString const& key, DeprecatedString const& value);
-    void write_bool_entry(DeprecatedString const& group, DeprecatedString const& key, bool value);
+    void write_entry(ByteString const& group, ByteString const& key, ByteString const& value);
+    void write_bool_entry(ByteString const& group, ByteString const& key, bool value);
 
     template<Integral T = int>
-    void write_num_entry(DeprecatedString const& group, DeprecatedString const& key, T value)
+    void write_num_entry(ByteString const& group, ByteString const& key, T value)
     {
-        write_entry(group, key, DeprecatedString::number(value));
+        write_entry(group, key, ByteString::number(value));
     }
 
     void dump() const;
@@ -76,20 +76,20 @@ public:
 
     ErrorOr<void> sync();
 
-    void add_group(DeprecatedString const& group);
-    void remove_group(DeprecatedString const& group);
-    void remove_entry(DeprecatedString const& group, DeprecatedString const& key);
+    void add_group(ByteString const& group);
+    void remove_group(ByteString const& group);
+    void remove_entry(ByteString const& group, ByteString const& key);
 
-    DeprecatedString const& filename() const { return m_filename; }
+    ByteString const& filename() const { return m_filename; }
 
 private:
-    ConfigFile(DeprecatedString const& filename, OwnPtr<InputBufferedFile> open_file);
+    ConfigFile(ByteString const& filename, OwnPtr<InputBufferedFile> open_file);
 
     ErrorOr<void> reparse();
 
-    DeprecatedString m_filename;
+    ByteString m_filename;
     OwnPtr<InputBufferedFile> m_file;
-    HashMap<DeprecatedString, HashMap<DeprecatedString, DeprecatedString>> m_groups;
+    HashMap<ByteString, HashMap<ByteString, ByteString>> m_groups;
     bool m_dirty { false };
 };
 
diff --git a/Userland/Libraries/LibCore/DateTime.cpp b/Userland/Libraries/LibCore/DateTime.cpp
index 000d684e0d5..14d3f86f9ae 100644
--- a/Userland/Libraries/LibCore/DateTime.cpp
+++ b/Userland/Libraries/LibCore/DateTime.cpp
@@ -283,9 +283,9 @@ ErrorOr<String> DateTime::to_string(StringView format) const
     return builder.to_string();
 }
 
-DeprecatedString DateTime::to_deprecated_string(StringView format) const
+ByteString DateTime::to_byte_string(StringView format) const
 {
-    return MUST(to_string(format)).to_deprecated_string();
+    return MUST(to_string(format)).to_byte_string();
 }
 
 Optional<DateTime> DateTime::parse(StringView format, StringView string)
diff --git a/Userland/Libraries/LibCore/DateTime.h b/Userland/Libraries/LibCore/DateTime.h
index d15dc9f40cf..724d8430afb 100644
--- a/Userland/Libraries/LibCore/DateTime.h
+++ b/Userland/Libraries/LibCore/DateTime.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringView.h>
 #include <LibIPC/Forward.h>
 #include <time.h>
@@ -32,7 +32,7 @@ public:
 
     void set_time(int year, int month = 1, int day = 1, int hour = 0, int minute = 0, int second = 0);
     ErrorOr<String> to_string(StringView format = "%Y-%m-%d %H:%M:%S"sv) const;
-    DeprecatedString to_deprecated_string(StringView format = "%Y-%m-%d %H:%M:%S"sv) const;
+    ByteString to_byte_string(StringView format = "%Y-%m-%d %H:%M:%S"sv) const;
 
     static DateTime create(int year, int month = 1, int day = 1, int hour = 0, int minute = 0, int second = 0);
     static DateTime now();
diff --git a/Userland/Libraries/LibCore/DirIterator.cpp b/Userland/Libraries/LibCore/DirIterator.cpp
index 0e5f2c4e13d..1151bf7b71d 100644
--- a/Userland/Libraries/LibCore/DirIterator.cpp
+++ b/Userland/Libraries/LibCore/DirIterator.cpp
@@ -11,7 +11,7 @@
 
 namespace Core {
 
-DirIterator::DirIterator(DeprecatedString path, Flags flags)
+DirIterator::DirIterator(ByteString path, Flags flags)
     : m_path(move(path))
     , m_flags(flags)
 {
@@ -93,7 +93,7 @@ Optional<DirectoryEntry> DirIterator::next()
     return result;
 }
 
-DeprecatedString DirIterator::next_path()
+ByteString DirIterator::next_path()
 {
     auto entry = next();
     if (entry.has_value())
@@ -101,14 +101,14 @@ DeprecatedString DirIterator::next_path()
     return "";
 }
 
-DeprecatedString DirIterator::next_full_path()
+ByteString DirIterator::next_full_path()
 {
     StringBuilder builder;
     builder.append(m_path);
     if (!m_path.ends_with('/'))
         builder.append('/');
     builder.append(next_path());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 int DirIterator::fd() const
diff --git a/Userland/Libraries/LibCore/DirIterator.h b/Userland/Libraries/LibCore/DirIterator.h
index fcdbfbe7741..bf9561e359b 100644
--- a/Userland/Libraries/LibCore/DirIterator.h
+++ b/Userland/Libraries/LibCore/DirIterator.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/DirectoryEntry.h>
 #include <dirent.h>
 #include <string.h>
@@ -22,7 +22,7 @@ public:
         SkipParentAndBaseDir = 0x2,
     };
 
-    explicit DirIterator(DeprecatedString path, Flags = Flags::NoFlags);
+    explicit DirIterator(ByteString path, Flags = Flags::NoFlags);
     ~DirIterator();
 
     DirIterator(DirIterator&&);
@@ -32,15 +32,15 @@ public:
     Error error() const { return Error::copy(m_error.value()); }
     bool has_next();
     Optional<DirectoryEntry> next();
-    DeprecatedString next_path();
-    DeprecatedString next_full_path();
+    ByteString next_path();
+    ByteString next_full_path();
     int fd() const;
 
 private:
     DIR* m_dir = nullptr;
     Optional<Error> m_error;
     Optional<DirectoryEntry> m_next;
-    DeprecatedString m_path;
+    ByteString m_path;
     int m_flags;
 
     bool advance_next();
diff --git a/Userland/Libraries/LibCore/Directory.cpp b/Userland/Libraries/LibCore/Directory.cpp
index 5509ee59478..482ae4ecce0 100644
--- a/Userland/Libraries/LibCore/Directory.cpp
+++ b/Userland/Libraries/LibCore/Directory.cpp
@@ -53,7 +53,7 @@ ErrorOr<Directory> Directory::adopt_fd(int fd, LexicalPath path)
     return Directory { fd, move(path) };
 }
 
-ErrorOr<Directory> Directory::create(DeprecatedString path, CreateDirectories create_directories, mode_t creation_mode)
+ErrorOr<Directory> Directory::create(ByteString path, CreateDirectories create_directories, mode_t creation_mode)
 {
     return create(LexicalPath { move(path) }, create_directories, creation_mode);
 }
diff --git a/Userland/Libraries/LibCore/Directory.h b/Userland/Libraries/LibCore/Directory.h
index 44b1048d19a..9f9b401ad93 100644
--- a/Userland/Libraries/LibCore/Directory.h
+++ b/Userland/Libraries/LibCore/Directory.h
@@ -37,7 +37,7 @@ public:
     };
 
     static ErrorOr<Directory> create(LexicalPath path, CreateDirectories, mode_t creation_mode = 0755);
-    static ErrorOr<Directory> create(DeprecatedString path, CreateDirectories, mode_t creation_mode = 0755);
+    static ErrorOr<Directory> create(ByteString path, CreateDirectories, mode_t creation_mode = 0755);
     static ErrorOr<Directory> adopt_fd(int fd, LexicalPath path);
 
     ErrorOr<NonnullOwnPtr<File>> open(StringView filename, File::OpenMode mode) const;
diff --git a/Userland/Libraries/LibCore/DirectoryEntry.h b/Userland/Libraries/LibCore/DirectoryEntry.h
index 83eed689586..7244ec83dd2 100644
--- a/Userland/Libraries/LibCore/DirectoryEntry.h
+++ b/Userland/Libraries/LibCore/DirectoryEntry.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <dirent.h>
 
 namespace Core {
@@ -25,7 +25,7 @@ struct DirectoryEntry {
     };
     Type type;
     // FIXME: Once we have a special Path string class, use that.
-    DeprecatedString name;
+    ByteString name;
     ino_t inode_number;
 
     static DirectoryEntry from_dirent(dirent const&);
diff --git a/Userland/Libraries/LibCore/EventReceiver.h b/Userland/Libraries/LibCore/EventReceiver.h
index 24d9c623fda..f51a788facf 100644
--- a/Userland/Libraries/LibCore/EventReceiver.h
+++ b/Userland/Libraries/LibCore/EventReceiver.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
@@ -67,8 +67,8 @@ public:
 
     virtual bool is_widget() const { return false; }
 
-    DeprecatedString const& name() const { return m_name; }
-    void set_name(DeprecatedString name) { m_name = move(name); }
+    ByteString const& name() const { return m_name; }
+    void set_name(ByteString name) { m_name = move(name); }
 
     Vector<NonnullRefPtr<EventReceiver>>& children() { return m_children; }
     Vector<NonnullRefPtr<EventReceiver>> const& children() const { return m_children; }
@@ -168,7 +168,7 @@ protected:
 
 private:
     EventReceiver* m_parent { nullptr };
-    DeprecatedString m_name;
+    ByteString m_name;
     int m_timer_id { 0 };
     Vector<NonnullRefPtr<EventReceiver>> m_children;
     Function<bool(Core::Event&)> m_event_filter;
diff --git a/Userland/Libraries/LibCore/FileWatcher.h b/Userland/Libraries/LibCore/FileWatcher.h
index 694e9f485bd..42bb783131f 100644
--- a/Userland/Libraries/LibCore/FileWatcher.h
+++ b/Userland/Libraries/LibCore/FileWatcher.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/EnumBits.h>
 #include <AK/Function.h>
 #include <AK/Noncopyable.h>
@@ -27,7 +27,7 @@ struct FileWatcherEvent {
         ChildDeleted = 1 << 4,
     };
     Type type { Type::Invalid };
-    DeprecatedString event_path;
+    ByteString event_path;
 };
 
 AK_ENUM_BITWISE_OPERATORS(FileWatcherEvent::Type);
@@ -44,9 +44,9 @@ class FileWatcherBase {
 public:
     virtual ~FileWatcherBase() = default;
 
-    ErrorOr<bool> add_watch(DeprecatedString path, FileWatcherEvent::Type event_mask);
-    ErrorOr<bool> remove_watch(DeprecatedString path);
-    bool is_watching(DeprecatedString const& path) const { return m_path_to_wd.find(path) != m_path_to_wd.end(); }
+    ErrorOr<bool> add_watch(ByteString path, FileWatcherEvent::Type event_mask);
+    ErrorOr<bool> remove_watch(ByteString path);
+    bool is_watching(ByteString const& path) const { return m_path_to_wd.find(path) != m_path_to_wd.end(); }
 
 protected:
     FileWatcherBase(int watcher_fd)
@@ -55,8 +55,8 @@ protected:
     }
 
     int m_watcher_fd { -1 };
-    HashMap<DeprecatedString, unsigned> m_path_to_wd;
-    HashMap<unsigned, DeprecatedString> m_wd_to_path;
+    HashMap<ByteString, unsigned> m_path_to_wd;
+    HashMap<unsigned, ByteString> m_wd_to_path;
 };
 
 class BlockingFileWatcher final : public FileWatcherBase {
diff --git a/Userland/Libraries/LibCore/FileWatcherLinux.cpp b/Userland/Libraries/LibCore/FileWatcherLinux.cpp
index 4c0ccdc969d..69f8d5e1c88 100644
--- a/Userland/Libraries/LibCore/FileWatcherLinux.cpp
+++ b/Userland/Libraries/LibCore/FileWatcherLinux.cpp
@@ -5,8 +5,8 @@
  */
 
 #include "FileWatcher.h"
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/LexicalPath.h>
 #include <LibCore/Notifier.h>
 #include <errno.h>
@@ -34,7 +34,7 @@ static constexpr unsigned file_watcher_flags_to_inotify_flags(FileWatcherFlags f
     return result;
 }
 
-static Optional<FileWatcherEvent> get_event_from_fd(int fd, HashMap<unsigned, DeprecatedString> const& wd_to_path)
+static Optional<FileWatcherEvent> get_event_from_fd(int fd, HashMap<unsigned, ByteString> const& wd_to_path)
 {
     static constexpr auto max_event_size = sizeof(inotify_event) + NAME_MAX + 1;
 
@@ -123,7 +123,7 @@ FileWatcher::FileWatcher(int watcher_fd, NonnullRefPtr<Notifier> notifier)
 
 FileWatcher::~FileWatcher() = default;
 
-ErrorOr<bool> FileWatcherBase::add_watch(DeprecatedString path, FileWatcherEvent::Type event_mask)
+ErrorOr<bool> FileWatcherBase::add_watch(ByteString path, FileWatcherEvent::Type event_mask)
 {
     if (m_path_to_wd.find(path) != m_path_to_wd.end()) {
         dbgln_if(FILE_WATCHER_DEBUG, "add_watch: path '{}' is already being watched", path);
@@ -154,7 +154,7 @@ ErrorOr<bool> FileWatcherBase::add_watch(DeprecatedString path, FileWatcherEvent
     return true;
 }
 
-ErrorOr<bool> FileWatcherBase::remove_watch(DeprecatedString path)
+ErrorOr<bool> FileWatcherBase::remove_watch(ByteString path)
 {
     auto it = m_path_to_wd.find(path);
     if (it == m_path_to_wd.end()) {
diff --git a/Userland/Libraries/LibCore/FileWatcherMacOS.mm b/Userland/Libraries/LibCore/FileWatcherMacOS.mm
index 4b718c65f9c..fcebf99335d 100644
--- a/Userland/Libraries/LibCore/FileWatcherMacOS.mm
+++ b/Userland/Libraries/LibCore/FileWatcherMacOS.mm
@@ -29,7 +29,7 @@ static_assert(false, "This file must only be used for macOS");
 namespace Core {
 
 struct MonitoredPath {
-    DeprecatedString path;
+    ByteString path;
     FileWatcherEvent::Type event_mask { FileWatcherEvent::Type::Invalid };
 };
 
@@ -55,7 +55,7 @@ public:
     {
         auto context = TRY(try_make<FSEventStreamContext>());
 
-        auto queue_name = DeprecatedString::formatted("Serenity.FileWatcher.{:p}", context.ptr());
+        auto queue_name = ByteString::formatted("Serenity.FileWatcher.{:p}", context.ptr());
         auto dispatch_queue = dispatch_queue_create(queue_name.characters(), DISPATCH_QUEUE_SERIAL);
         if (dispatch_queue == nullptr)
             return Error::from_errno(errno);
@@ -67,7 +67,7 @@ public:
         return adopt_nonnull_ref_or_enomem(new (nothrow) FileWatcherMacOS(move(context), dispatch_queue, move(notifier)));
     }
 
-    ErrorOr<bool> add_watch(DeprecatedString path, FileWatcherEvent::Type event_mask)
+    ErrorOr<bool> add_watch(ByteString path, FileWatcherEvent::Type event_mask)
     {
         if (m_path_to_inode_id.contains(path)) {
             dbgln_if(FILE_WATCHER_DEBUG, "add_watch: path '{}' is already being watched", path);
@@ -84,7 +84,7 @@ public:
         return true;
     }
 
-    ErrorOr<bool> remove_watch(DeprecatedString path)
+    ErrorOr<bool> remove_watch(ByteString path)
     {
         auto it = m_path_to_inode_id.find(path);
         if (it == m_path_to_inode_id.end()) {
@@ -101,7 +101,7 @@ public:
         return true;
     }
 
-    ErrorOr<MonitoredPath> canonicalize_path(DeprecatedString path)
+    ErrorOr<MonitoredPath> canonicalize_path(ByteString path)
     {
         LexicalPath lexical_path { move(path) };
         auto parent_path = lexical_path.parent();
@@ -200,7 +200,7 @@ private:
     dispatch_queue_t m_dispatch_queue { nullptr };
     FSEventStreamRef m_stream { nullptr };
 
-    HashMap<DeprecatedString, ino_t> m_path_to_inode_id;
+    HashMap<ByteString, ino_t> m_path_to_inode_id;
     HashMap<ino_t, MonitoredPath> m_inode_id_to_path;
 };
 
@@ -219,7 +219,7 @@ void on_file_system_event(ConstFSEventStreamRef, void* user_data, size_t event_s
             continue;
         }
 
-        auto maybe_monitored_path = file_watcher.canonicalize_path(DeprecatedString { file_path_buffer });
+        auto maybe_monitored_path = file_watcher.canonicalize_path(ByteString { file_path_buffer });
         if (maybe_monitored_path.is_error()) {
             dbgln_if(FILE_WATCHER_DEBUG, "Could not canonicalize path {}: {}", file_path_buffer, maybe_monitored_path.error());
             continue;
@@ -265,13 +265,13 @@ FileWatcher::FileWatcher(int watcher_fd, NonnullRefPtr<Notifier> notifier)
 
 FileWatcher::~FileWatcher() = default;
 
-ErrorOr<bool> FileWatcherBase::add_watch(DeprecatedString path, FileWatcherEvent::Type event_mask)
+ErrorOr<bool> FileWatcherBase::add_watch(ByteString path, FileWatcherEvent::Type event_mask)
 {
     auto& file_watcher = verify_cast<FileWatcherMacOS>(*this);
     return file_watcher.add_watch(move(path), event_mask);
 }
 
-ErrorOr<bool> FileWatcherBase::remove_watch(DeprecatedString path)
+ErrorOr<bool> FileWatcherBase::remove_watch(ByteString path)
 {
     auto& file_watcher = verify_cast<FileWatcherMacOS>(*this);
     return file_watcher.remove_watch(move(path));
diff --git a/Userland/Libraries/LibCore/FileWatcherSerenity.cpp b/Userland/Libraries/LibCore/FileWatcherSerenity.cpp
index 946826981e9..4e347bd334b 100644
--- a/Userland/Libraries/LibCore/FileWatcherSerenity.cpp
+++ b/Userland/Libraries/LibCore/FileWatcherSerenity.cpp
@@ -6,8 +6,8 @@
  */
 
 #include "FileWatcher.h"
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/LexicalPath.h>
 #include <AK/NonnullRefPtr.h>
 #include <Kernel/API/InodeWatcherEvent.h>
@@ -36,7 +36,7 @@ static constexpr unsigned file_watcher_flags_to_inode_watcher_flags(FileWatcherF
     return static_cast<unsigned>(result);
 }
 
-static Optional<FileWatcherEvent> get_event_from_fd(int fd, HashMap<unsigned, DeprecatedString> const& wd_to_path)
+static Optional<FileWatcherEvent> get_event_from_fd(int fd, HashMap<unsigned, ByteString> const& wd_to_path)
 {
     u8 buffer[MAXIMUM_EVENT_SIZE];
     int rc = read(fd, &buffer, MAXIMUM_EVENT_SIZE);
@@ -55,7 +55,7 @@ static Optional<FileWatcherEvent> get_event_from_fd(int fd, HashMap<unsigned, De
         dbgln_if(FILE_WATCHER_DEBUG, "get_event_from_fd: Got an event for a non-existent wd {}?!", event->watch_descriptor);
         return {};
     }
-    DeprecatedString const& path = it->value;
+    ByteString const& path = it->value;
 
     switch (event->type) {
     case InodeWatcherEvent::Type::ChildCreated:
@@ -80,7 +80,7 @@ static Optional<FileWatcherEvent> get_event_from_fd(int fd, HashMap<unsigned, De
 
     // We trust that the kernel only sends the name when appropriate.
     if (event->name_length > 0) {
-        DeprecatedString child_name { event->name, event->name_length - 1 };
+        ByteString child_name { event->name, event->name_length - 1 };
         result.event_path = LexicalPath::join(path, child_name).string();
     } else {
         result.event_path = path;
@@ -90,7 +90,7 @@ static Optional<FileWatcherEvent> get_event_from_fd(int fd, HashMap<unsigned, De
     return result;
 }
 
-static DeprecatedString canonicalize_path(DeprecatedString path)
+static ByteString canonicalize_path(ByteString path)
 {
     if (!path.is_empty() && path[0] == '/')
         return LexicalPath::canonicalized_path(move(path));
@@ -99,9 +99,9 @@ static DeprecatedString canonicalize_path(DeprecatedString path)
     return LexicalPath::join({ cwd, strlen(cwd) }, move(path)).string();
 }
 
-ErrorOr<bool> FileWatcherBase::add_watch(DeprecatedString path, FileWatcherEvent::Type event_mask)
+ErrorOr<bool> FileWatcherBase::add_watch(ByteString path, FileWatcherEvent::Type event_mask)
 {
-    DeprecatedString canonical_path = canonicalize_path(move(path));
+    ByteString canonical_path = canonicalize_path(move(path));
 
     if (m_path_to_wd.find(canonical_path) != m_path_to_wd.end()) {
         dbgln_if(FILE_WATCHER_DEBUG, "add_watch: path '{}' is already being watched", canonical_path);
@@ -131,9 +131,9 @@ ErrorOr<bool> FileWatcherBase::add_watch(DeprecatedString path, FileWatcherEvent
     return true;
 }
 
-ErrorOr<bool> FileWatcherBase::remove_watch(DeprecatedString path)
+ErrorOr<bool> FileWatcherBase::remove_watch(ByteString path)
 {
-    DeprecatedString canonical_path = canonicalize_path(move(path));
+    ByteString canonical_path = canonicalize_path(move(path));
 
     auto it = m_path_to_wd.find(canonical_path);
     if (it == m_path_to_wd.end()) {
diff --git a/Userland/Libraries/LibCore/FileWatcherUnimplemented.cpp b/Userland/Libraries/LibCore/FileWatcherUnimplemented.cpp
index 2e12ac688f0..81a33e26d88 100644
--- a/Userland/Libraries/LibCore/FileWatcherUnimplemented.cpp
+++ b/Userland/Libraries/LibCore/FileWatcherUnimplemented.cpp
@@ -24,12 +24,12 @@ FileWatcher::FileWatcher(int watcher_fd, NonnullRefPtr<Notifier> notifier)
 
 FileWatcher::~FileWatcher() = default;
 
-ErrorOr<bool> FileWatcherBase::add_watch(DeprecatedString, FileWatcherEvent::Type)
+ErrorOr<bool> FileWatcherBase::add_watch(ByteString, FileWatcherEvent::Type)
 {
     return Error::from_errno(ENOTSUP);
 }
 
-ErrorOr<bool> FileWatcherBase::remove_watch(DeprecatedString)
+ErrorOr<bool> FileWatcherBase::remove_watch(ByteString)
 {
     return Error::from_errno(ENOTSUP);
 }
diff --git a/Userland/Libraries/LibCore/Group.cpp b/Userland/Libraries/LibCore/Group.cpp
index bc60a08caf2..7f1c07722a3 100644
--- a/Userland/Libraries/LibCore/Group.cpp
+++ b/Userland/Libraries/LibCore/Group.cpp
@@ -15,7 +15,7 @@
 
 namespace Core {
 
-ErrorOr<DeprecatedString> Group::generate_group_file() const
+ErrorOr<ByteString> Group::generate_group_file() const
 {
     StringBuilder builder;
     char buffer[1024] = { 0 };
@@ -29,19 +29,19 @@ ErrorOr<DeprecatedString> Group::generate_group_file() const
             break;
 
         if (group->gr_name == m_name)
-            builder.appendff("{}:x:{}:{}\n", m_name, m_id, DeprecatedString::join(',', m_members));
+            builder.appendff("{}:x:{}:{}\n", m_name, m_id, ByteString::join(',', m_members));
         else {
-            Vector<DeprecatedString> members;
+            Vector<ByteString> members;
             if (group->gr_mem) {
                 for (size_t i = 0; group->gr_mem[i]; ++i)
                     members.append(group->gr_mem[i]);
             }
 
-            builder.appendff("{}:x:{}:{}\n", group->gr_name, group->gr_gid, DeprecatedString::join(',', members));
+            builder.appendff("{}:x:{}:{}\n", group->gr_name, group->gr_gid, ByteString::join(',', members));
         }
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 ErrorOr<void> Group::sync()
@@ -74,7 +74,7 @@ ErrorOr<void> Group::add_group(Group& group)
         return Error::from_string_literal("Group name can not be empty.");
 
     // A quick sanity check on group name
-    if (group.name().find_any_of("\\/!@#$%^&*()~+=`:\n"sv, DeprecatedString::SearchDirection::Forward).has_value())
+    if (group.name().find_any_of("\\/!@#$%^&*()~+=`:\n"sv, ByteString::SearchDirection::Forward).has_value())
         return Error::from_string_literal("Group name has invalid characters.");
 
     // Disallow names starting with '_', '-' or other non-alpha characters.
@@ -129,7 +129,7 @@ ErrorOr<Vector<Group>> Group::all()
         if (!group.has_value())
             break;
 
-        Vector<DeprecatedString> members;
+        Vector<ByteString> members;
         if (group->gr_mem) {
             for (size_t i = 0; group->gr_mem[i]; ++i)
                 members.append(group->gr_mem[i]);
@@ -141,7 +141,7 @@ ErrorOr<Vector<Group>> Group::all()
     return groups;
 }
 
-Group::Group(DeprecatedString name, gid_t id, Vector<DeprecatedString> members)
+Group::Group(ByteString name, gid_t id, Vector<ByteString> members)
     : m_name(move(name))
     , m_id(id)
     , m_members(move(members))
diff --git a/Userland/Libraries/LibCore/Group.h b/Userland/Libraries/LibCore/Group.h
index 53d3617d191..3a985247a4b 100644
--- a/Userland/Libraries/LibCore/Group.h
+++ b/Userland/Libraries/LibCore/Group.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Vector.h>
 #include <grp.h>
@@ -22,17 +22,17 @@ public:
     static ErrorOr<Vector<Group>> all();
 
     Group() = default;
-    Group(DeprecatedString name, gid_t id = 0, Vector<DeprecatedString> members = {});
+    Group(ByteString name, gid_t id = 0, Vector<ByteString> members = {});
 
     ~Group() = default;
 
-    DeprecatedString const& name() const { return m_name; }
-    void set_name(DeprecatedString const& name) { m_name = name; }
+    ByteString const& name() const { return m_name; }
+    void set_name(ByteString const& name) { m_name = name; }
 
     gid_t id() const { return m_id; }
     void set_group_id(gid_t const id) { m_id = id; }
 
-    Vector<DeprecatedString>& members() { return m_members; }
+    Vector<ByteString>& members() { return m_members; }
 
     ErrorOr<void> sync();
 
@@ -41,11 +41,11 @@ private:
     static ErrorOr<bool> id_exists(gid_t id);
     ErrorOr<struct group> to_libc_group();
 
-    ErrorOr<DeprecatedString> generate_group_file() const;
+    ErrorOr<ByteString> generate_group_file() const;
 
-    DeprecatedString m_name;
+    ByteString m_name;
     gid_t m_id { 0 };
-    Vector<DeprecatedString> m_members;
+    Vector<ByteString> m_members;
 };
 
 }
diff --git a/Userland/Libraries/LibCore/LocalServer.cpp b/Userland/Libraries/LibCore/LocalServer.cpp
index 6051526213e..a96c6043db8 100644
--- a/Userland/Libraries/LibCore/LocalServer.cpp
+++ b/Userland/Libraries/LibCore/LocalServer.cpp
@@ -33,7 +33,7 @@ LocalServer::~LocalServer()
         ::close(m_fd);
 }
 
-ErrorOr<void> LocalServer::take_over_from_system_server(DeprecatedString const& socket_path)
+ErrorOr<void> LocalServer::take_over_from_system_server(ByteString const& socket_path)
 {
     if (m_listening)
         return Error::from_string_literal("Core::LocalServer: Can't perform socket takeover when already listening");
@@ -65,7 +65,7 @@ void LocalServer::setup_notifier()
     };
 }
 
-bool LocalServer::listen(DeprecatedString const& address)
+bool LocalServer::listen(ByteString const& address)
 {
     if (m_listening)
         return false;
diff --git a/Userland/Libraries/LibCore/LocalServer.h b/Userland/Libraries/LibCore/LocalServer.h
index d2a9e8b4862..cdccfcb6eb4 100644
--- a/Userland/Libraries/LibCore/LocalServer.h
+++ b/Userland/Libraries/LibCore/LocalServer.h
@@ -16,9 +16,9 @@ class LocalServer : public EventReceiver {
 public:
     virtual ~LocalServer() override;
 
-    ErrorOr<void> take_over_from_system_server(DeprecatedString const& path = DeprecatedString());
+    ErrorOr<void> take_over_from_system_server(ByteString const& path = ByteString());
     bool is_listening() const { return m_listening; }
-    bool listen(DeprecatedString const& address);
+    bool listen(ByteString const& address);
 
     ErrorOr<NonnullOwnPtr<LocalSocket>> accept();
 
diff --git a/Userland/Libraries/LibCore/MimeData.cpp b/Userland/Libraries/LibCore/MimeData.cpp
index 9a68f9f39ce..716046bc20b 100644
--- a/Userland/Libraries/LibCore/MimeData.cpp
+++ b/Userland/Libraries/LibCore/MimeData.cpp
@@ -27,7 +27,7 @@ ErrorOr<void> MimeData::set_urls(Vector<URL> const& urls)
 {
     StringBuilder builder;
     for (auto& url : urls) {
-        TRY(builder.try_append(url.to_deprecated_string()));
+        TRY(builder.try_append(url.to_byte_string()));
         TRY(builder.try_append('\n'));
     }
     set_data("text/uri-list"_string, TRY(builder.to_byte_buffer()));
@@ -35,12 +35,12 @@ ErrorOr<void> MimeData::set_urls(Vector<URL> const& urls)
     return {};
 }
 
-DeprecatedString MimeData::text() const
+ByteString MimeData::text() const
 {
-    return DeprecatedString::copy(m_data.get("text/plain"sv).value_or({}));
+    return ByteString::copy(m_data.get("text/plain"sv).value_or({}));
 }
 
-void MimeData::set_text(DeprecatedString const& text)
+void MimeData::set_text(ByteString const& text)
 {
     set_data("text/plain"_string, text.to_byte_buffer());
 }
diff --git a/Userland/Libraries/LibCore/MimeData.h b/Userland/Libraries/LibCore/MimeData.h
index 64b24df8533..ee70e506b51 100644
--- a/Userland/Libraries/LibCore/MimeData.h
+++ b/Userland/Libraries/LibCore/MimeData.h
@@ -28,8 +28,8 @@ public:
 
     // Convenience helpers for "text/plain"
     bool has_text() const { return has_format("text/plain"sv); }
-    DeprecatedString text() const;
-    void set_text(DeprecatedString const&);
+    ByteString text() const;
+    void set_text(ByteString const&);
 
     // Convenience helpers for "text/uri-list"
     bool has_urls() const { return has_format("text/uri-list"sv); }
diff --git a/Userland/Libraries/LibCore/NetworkJob.h b/Userland/Libraries/LibCore/NetworkJob.h
index 3e790a098e4..dad0f5a5390 100644
--- a/Userland/Libraries/LibCore/NetworkJob.h
+++ b/Userland/Libraries/LibCore/NetworkJob.h
@@ -27,7 +27,7 @@ public:
     virtual ~NetworkJob() override = default;
 
     // Could fire twice, after Headers and after Trailers!
-    Function<void(HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code)> on_headers_received;
+    Function<void(HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code)> on_headers_received;
     Function<void(bool success)> on_finish;
     Function<void(Optional<u64>, u64)> on_progress;
 
diff --git a/Userland/Libraries/LibCore/Process.cpp b/Userland/Libraries/LibCore/Process.cpp
index f4ea72ec000..b7912ecd4ca 100644
--- a/Userland/Libraries/LibCore/Process.cpp
+++ b/Userland/Libraries/LibCore/Process.cpp
@@ -6,7 +6,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/ScopeGuard.h>
 #include <AK/String.h>
 #include <AK/Vector.h>
@@ -35,10 +35,10 @@ extern "C" {
 namespace Core {
 
 struct ArgvList {
-    DeprecatedString m_path;
+    ByteString m_path;
     Vector<char const*, 10> m_argv;
 
-    ArgvList(DeprecatedString path, size_t size)
+    ArgvList(ByteString path, size_t size)
         : m_path { path }
     {
         m_argv.ensure_capacity(size + 2);
@@ -103,12 +103,12 @@ ErrorOr<Process> Process::spawn(ProcessSpawnOptions const& options)
     return Process { pid };
 }
 
-ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<DeprecatedString> arguments, DeprecatedString working_directory, KeepAsChild keep_as_child)
+ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<ByteString> arguments, ByteString working_directory, KeepAsChild keep_as_child)
 {
     auto process = TRY(spawn({
         .path = path,
-        .arguments = Vector<DeprecatedString> { arguments },
-        .working_directory = working_directory.is_empty() ? Optional<DeprecatedString> {} : Optional<DeprecatedString> { working_directory },
+        .arguments = Vector<ByteString> { arguments },
+        .working_directory = working_directory.is_empty() ? Optional<ByteString> {} : Optional<ByteString> { working_directory },
     }));
 
     if (keep_as_child == KeepAsChild::No)
@@ -120,9 +120,9 @@ ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<DeprecatedString> ar
     return process.pid();
 }
 
-ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<StringView> arguments, DeprecatedString working_directory, KeepAsChild keep_as_child)
+ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<StringView> arguments, ByteString working_directory, KeepAsChild keep_as_child)
 {
-    Vector<DeprecatedString> backing_strings;
+    Vector<ByteString> backing_strings;
     backing_strings.ensure_capacity(arguments.size());
     for (auto const& argument : arguments)
         backing_strings.append(argument);
@@ -130,7 +130,7 @@ ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<StringView> argument
     auto process = TRY(spawn({
         .path = path,
         .arguments = backing_strings,
-        .working_directory = working_directory.is_empty() ? Optional<DeprecatedString> {} : Optional<DeprecatedString> { working_directory },
+        .working_directory = working_directory.is_empty() ? Optional<ByteString> {} : Optional<ByteString> { working_directory },
     }));
 
     if (keep_as_child == KeepAsChild::No)
@@ -140,9 +140,9 @@ ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<StringView> argument
     return process.pid();
 }
 
-ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<char const*> arguments, DeprecatedString working_directory, KeepAsChild keep_as_child)
+ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<char const*> arguments, ByteString working_directory, KeepAsChild keep_as_child)
 {
-    Vector<DeprecatedString> backing_strings;
+    Vector<ByteString> backing_strings;
     backing_strings.ensure_capacity(arguments.size());
     for (auto const& argument : arguments)
         backing_strings.append(argument);
@@ -150,7 +150,7 @@ ErrorOr<pid_t> Process::spawn(StringView path, ReadonlySpan<char const*> argumen
     auto process = TRY(spawn({
         .path = path,
         .arguments = backing_strings,
-        .working_directory = working_directory.is_empty() ? Optional<DeprecatedString> {} : Optional<DeprecatedString> { working_directory },
+        .working_directory = working_directory.is_empty() ? Optional<ByteString> {} : Optional<ByteString> { working_directory },
     }));
 
     if (keep_as_child == KeepAsChild::No)
diff --git a/Userland/Libraries/LibCore/Process.h b/Userland/Libraries/LibCore/Process.h
index 36db835d1fc..d50fb856d48 100644
--- a/Userland/Libraries/LibCore/Process.h
+++ b/Userland/Libraries/LibCore/Process.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/Span.h>
 #include <LibCore/File.h>
@@ -18,7 +18,7 @@ namespace Core {
 namespace FileAction {
 
 struct OpenFile {
-    DeprecatedString path;
+    ByteString path;
     File::OpenMode mode = File::OpenMode::NotOpen;
     int fd = -1;
     mode_t permissions = 0600;
@@ -29,9 +29,9 @@ struct OpenFile {
 }
 
 struct ProcessSpawnOptions {
-    DeprecatedString path;
-    Vector<DeprecatedString> const& arguments = {};
-    Optional<DeprecatedString> working_directory = {};
+    ByteString path;
+    Vector<ByteString> const& arguments = {};
+    Optional<ByteString> working_directory = {};
     Vector<Variant<FileAction::OpenFile>> const& file_actions = {};
 };
 
@@ -60,11 +60,11 @@ public:
     static ErrorOr<Process> spawn(ProcessSpawnOptions const& options);
 
     // FIXME: Make the following 2 functions return Process instance or delete them.
-    static ErrorOr<pid_t> spawn(StringView path, ReadonlySpan<DeprecatedString> arguments, DeprecatedString working_directory = {}, KeepAsChild keep_as_child = KeepAsChild::No);
-    static ErrorOr<pid_t> spawn(StringView path, ReadonlySpan<StringView> arguments, DeprecatedString working_directory = {}, KeepAsChild keep_as_child = KeepAsChild::No);
+    static ErrorOr<pid_t> spawn(StringView path, ReadonlySpan<ByteString> arguments, ByteString working_directory = {}, KeepAsChild keep_as_child = KeepAsChild::No);
+    static ErrorOr<pid_t> spawn(StringView path, ReadonlySpan<StringView> arguments, ByteString working_directory = {}, KeepAsChild keep_as_child = KeepAsChild::No);
 
     // FIXME: Remove this. char const* should not exist on this level of abstraction.
-    static ErrorOr<pid_t> spawn(StringView path, ReadonlySpan<char const*> arguments = {}, DeprecatedString working_directory = {}, KeepAsChild keep_as_child = KeepAsChild::No);
+    static ErrorOr<pid_t> spawn(StringView path, ReadonlySpan<char const*> arguments = {}, ByteString working_directory = {}, KeepAsChild keep_as_child = KeepAsChild::No);
 
     static ErrorOr<String> get_name();
     enum class SetThreadName {
diff --git a/Userland/Libraries/LibCore/ProcessStatisticsReader.cpp b/Userland/Libraries/LibCore/ProcessStatisticsReader.cpp
index 43e8d3bab2b..de66ac1f006 100644
--- a/Userland/Libraries/LibCore/ProcessStatisticsReader.cpp
+++ b/Userland/Libraries/LibCore/ProcessStatisticsReader.cpp
@@ -14,7 +14,7 @@
 
 namespace Core {
 
-HashMap<uid_t, DeprecatedString> ProcessStatisticsReader::s_usernames;
+HashMap<uid_t, ByteString> ProcessStatisticsReader::s_usernames;
 
 ErrorOr<AllProcessesStatistics> ProcessStatisticsReader::get_all(SeekableStream& proc_all_file, bool include_usernames)
 {
@@ -37,11 +37,11 @@ ErrorOr<AllProcessesStatistics> ProcessStatisticsReader::get_all(SeekableStream&
         process.gid = process_object.get_u32("gid"sv).value_or(0);
         process.ppid = process_object.get_u32("ppid"sv).value_or(0);
         process.kernel = process_object.get_bool("kernel"sv).value_or(false);
-        process.name = process_object.get_deprecated_string("name"sv).value_or("");
-        process.executable = process_object.get_deprecated_string("executable"sv).value_or("");
-        process.tty = process_object.get_deprecated_string("tty"sv).value_or("");
-        process.pledge = process_object.get_deprecated_string("pledge"sv).value_or("");
-        process.veil = process_object.get_deprecated_string("veil"sv).value_or("");
+        process.name = process_object.get_byte_string("name"sv).value_or("");
+        process.executable = process_object.get_byte_string("executable"sv).value_or("");
+        process.tty = process_object.get_byte_string("tty"sv).value_or("");
+        process.pledge = process_object.get_byte_string("pledge"sv).value_or("");
+        process.veil = process_object.get_byte_string("veil"sv).value_or("");
         process.creation_time = UnixDateTime::from_nanoseconds_since_epoch(process_object.get_i64("creation_time"sv).value_or(0));
         process.amount_virtual = process_object.get_u32("amount_virtual"sv).value_or(0);
         process.amount_resident = process_object.get_u32("amount_resident"sv).value_or(0);
@@ -58,8 +58,8 @@ ErrorOr<AllProcessesStatistics> ProcessStatisticsReader::get_all(SeekableStream&
             Core::ThreadStatistics thread;
             thread.tid = thread_object.get_u32("tid"sv).value_or(0);
             thread.times_scheduled = thread_object.get_u32("times_scheduled"sv).value_or(0);
-            thread.name = thread_object.get_deprecated_string("name"sv).value_or("");
-            thread.state = thread_object.get_deprecated_string("state"sv).value_or("");
+            thread.name = thread_object.get_byte_string("name"sv).value_or("");
+            thread.state = thread_object.get_byte_string("state"sv).value_or("");
             thread.time_user = thread_object.get_u64("time_user"sv).value_or(0);
             thread.time_kernel = thread_object.get_u64("time_kernel"sv).value_or(0);
             thread.cpu = thread_object.get_u32("cpu"sv).value_or(0);
@@ -95,7 +95,7 @@ ErrorOr<AllProcessesStatistics> ProcessStatisticsReader::get_all(bool include_us
     return get_all(*proc_all_file, include_usernames);
 }
 
-DeprecatedString ProcessStatisticsReader::username_from_uid(uid_t uid)
+ByteString ProcessStatisticsReader::username_from_uid(uid_t uid)
 {
     if (s_usernames.is_empty()) {
         setpwent();
@@ -107,6 +107,6 @@ DeprecatedString ProcessStatisticsReader::username_from_uid(uid_t uid)
     auto it = s_usernames.find(uid);
     if (it != s_usernames.end())
         return (*it).value;
-    return DeprecatedString::number(uid);
+    return ByteString::number(uid);
 }
 }
diff --git a/Userland/Libraries/LibCore/ProcessStatisticsReader.h b/Userland/Libraries/LibCore/ProcessStatisticsReader.h
index ded72705a42..e30c97242f5 100644
--- a/Userland/Libraries/LibCore/ProcessStatisticsReader.h
+++ b/Userland/Libraries/LibCore/ProcessStatisticsReader.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Time.h>
 #include <AK/Vector.h>
 #include <unistd.h>
@@ -28,10 +28,10 @@ struct ThreadStatistics {
     u64 ipv4_socket_write_bytes;
     u64 file_read_bytes;
     u64 file_write_bytes;
-    DeprecatedString state;
+    ByteString state;
     u32 cpu;
     u32 priority;
-    DeprecatedString name;
+    ByteString name;
 };
 
 struct ProcessStatistics {
@@ -45,11 +45,11 @@ struct ProcessStatistics {
     gid_t gid;
     pid_t ppid;
     bool kernel;
-    DeprecatedString name;
-    DeprecatedString executable;
-    DeprecatedString tty;
-    DeprecatedString pledge;
-    DeprecatedString veil;
+    ByteString name;
+    ByteString executable;
+    ByteString tty;
+    ByteString pledge;
+    ByteString veil;
     UnixDateTime creation_time;
     size_t amount_virtual;
     size_t amount_resident;
@@ -62,7 +62,7 @@ struct ProcessStatistics {
     Vector<Core::ThreadStatistics> threads;
 
     // synthetic
-    DeprecatedString username;
+    ByteString username;
 };
 
 struct AllProcessesStatistics {
@@ -77,8 +77,8 @@ public:
     static ErrorOr<AllProcessesStatistics> get_all(bool include_usernames = true);
 
 private:
-    static DeprecatedString username_from_uid(uid_t);
-    static HashMap<uid_t, DeprecatedString> s_usernames;
+    static ByteString username_from_uid(uid_t);
+    static HashMap<uid_t, ByteString> s_usernames;
 };
 
 }
diff --git a/Userland/Libraries/LibCore/ResourceImplementation.cpp b/Userland/Libraries/LibCore/ResourceImplementation.cpp
index e1852b3aeea..347d91d5921 100644
--- a/Userland/Libraries/LibCore/ResourceImplementation.cpp
+++ b/Userland/Libraries/LibCore/ResourceImplementation.cpp
@@ -72,9 +72,9 @@ Vector<String> ResourceImplementation::child_names(Resource const& resource)
     VERIFY(resource.m_scheme == Resource::Scheme::File);
 
     Vector<String> children;
-    Core::DirIterator it(resource.filesystem_path().to_deprecated_string(), Core::DirIterator::SkipParentAndBaseDir);
+    Core::DirIterator it(resource.filesystem_path().to_byte_string(), Core::DirIterator::SkipParentAndBaseDir);
     while (it.has_next())
-        children.append(MUST(String::from_deprecated_string(it.next_path())));
+        children.append(MUST(String::from_byte_string(it.next_path())));
 
     return children;
 }
diff --git a/Userland/Libraries/LibCore/ResourceImplementationFile.cpp b/Userland/Libraries/LibCore/ResourceImplementationFile.cpp
index 894afe81fe1..566b83e3edb 100644
--- a/Userland/Libraries/LibCore/ResourceImplementationFile.cpp
+++ b/Userland/Libraries/LibCore/ResourceImplementationFile.cpp
@@ -24,7 +24,7 @@ ErrorOr<NonnullRefPtr<Resource>> ResourceImplementationFile::load_from_resource_
     VERIFY(uri.starts_with(resource_scheme));
 
     auto path = TRY(String::from_utf8(uri.substring_view(resource_scheme.length())));
-    auto full_path = TRY(String::from_deprecated_string(LexicalPath::join(m_base_directory, path).string()));
+    auto full_path = TRY(String::from_byte_string(LexicalPath::join(m_base_directory, path).string()));
     if (is_directory(full_path))
         return make_directory_resource(move(path));
 
@@ -34,16 +34,16 @@ ErrorOr<NonnullRefPtr<Resource>> ResourceImplementationFile::load_from_resource_
 Vector<String> ResourceImplementationFile::child_names_for_resource_scheme(Resource const& resource)
 {
     Vector<String> children;
-    Core::DirIterator it(resource.filesystem_path().to_deprecated_string(), Core::DirIterator::SkipParentAndBaseDir);
+    Core::DirIterator it(resource.filesystem_path().to_byte_string(), Core::DirIterator::SkipParentAndBaseDir);
     while (it.has_next())
-        children.append(MUST(String::from_deprecated_string(it.next_path())));
+        children.append(MUST(String::from_byte_string(it.next_path())));
 
     return children;
 }
 
 String ResourceImplementationFile::filesystem_path_for_resource_scheme(String const& relative_path)
 {
-    return MUST(String::from_deprecated_string(LexicalPath::join(m_base_directory, relative_path).string()));
+    return MUST(String::from_byte_string(LexicalPath::join(m_base_directory, relative_path).string()));
 }
 
 }
diff --git a/Userland/Libraries/LibCore/SOCKSProxyClient.cpp b/Userland/Libraries/LibCore/SOCKSProxyClient.cpp
index 199def7297c..db738c47ba4 100644
--- a/Userland/Libraries/LibCore/SOCKSProxyClient.cpp
+++ b/Userland/Libraries/LibCore/SOCKSProxyClient.cpp
@@ -161,7 +161,7 @@ ErrorOr<Reply> send_connect_request_message(Core::Socket& socket, Core::SOCKSPro
     TRY(stream.write_value(header));
 
     TRY(target.visit(
-        [&](DeprecatedString const& hostname) -> ErrorOr<void> {
+        [&](ByteString const& hostname) -> ErrorOr<void> {
             u8 address_data[2];
             address_data[0] = to_underlying(AddressType::DomainName);
             address_data[1] = hostname.length();
@@ -298,7 +298,7 @@ ErrorOr<NonnullOwnPtr<SOCKSProxyClient>> SOCKSProxyClient::connect(HostOrIPV4 co
         [&](u32 ipv4) {
             return Core::TCPSocket::connect({ IPv4Address(ipv4), static_cast<u16>(server_port) });
         },
-        [&](DeprecatedString const& hostname) {
+        [&](ByteString const& hostname) {
             return Core::TCPSocket::connect(hostname, static_cast<u16>(server_port));
         }));
 
diff --git a/Userland/Libraries/LibCore/SOCKSProxyClient.h b/Userland/Libraries/LibCore/SOCKSProxyClient.h
index 24b47bb606b..cbb816870df 100644
--- a/Userland/Libraries/LibCore/SOCKSProxyClient.h
+++ b/Userland/Libraries/LibCore/SOCKSProxyClient.h
@@ -19,8 +19,8 @@ public:
     };
 
     struct UsernamePasswordAuthenticationData {
-        DeprecatedString username;
-        DeprecatedString password;
+        ByteString username;
+        ByteString password;
     };
 
     enum class Command : u8 {
@@ -29,7 +29,7 @@ public:
         UDPAssociate = 0x03,
     };
 
-    using HostOrIPV4 = Variant<DeprecatedString, u32>;
+    using HostOrIPV4 = Variant<ByteString, u32>;
 
     static ErrorOr<NonnullOwnPtr<SOCKSProxyClient>> connect(Socket& underlying, Version, HostOrIPV4 const& target, int target_port, Variant<UsernamePasswordAuthenticationData, Empty> const& auth_data = {}, Command = Command::Connect);
     static ErrorOr<NonnullOwnPtr<SOCKSProxyClient>> connect(HostOrIPV4 const& server, int server_port, Version, HostOrIPV4 const& target, int target_port, Variant<UsernamePasswordAuthenticationData, Empty> const& auth_data = {}, Command = Command::Connect);
diff --git a/Userland/Libraries/LibCore/SessionManagement.cpp b/Userland/Libraries/LibCore/SessionManagement.cpp
index a12fef8210a..6ec367c3a69 100644
--- a/Userland/Libraries/LibCore/SessionManagement.cpp
+++ b/Userland/Libraries/LibCore/SessionManagement.cpp
@@ -34,19 +34,19 @@ ErrorOr<void> logout(Optional<pid_t> force_sid)
     return {};
 }
 
-ErrorOr<DeprecatedString> parse_path_with_sid(StringView general_path, Optional<pid_t> force_sid)
+ErrorOr<ByteString> parse_path_with_sid(StringView general_path, Optional<pid_t> force_sid)
 {
     if (general_path.contains("%sid"sv)) {
         pid_t sid = TRY(root_session_id(force_sid));
-        return general_path.replace("%sid"sv, DeprecatedString::number(sid), ReplaceMode::All);
+        return general_path.replace("%sid"sv, ByteString::number(sid), ReplaceMode::All);
     }
-    return DeprecatedString(general_path);
+    return ByteString(general_path);
 }
 
 ErrorOr<void> create_session_temporary_directory_if_needed(uid_t uid, gid_t gid, Optional<pid_t> force_sid)
 {
     pid_t sid = TRY(root_session_id(force_sid));
-    auto const temporary_directory = DeprecatedString::formatted("/tmp/session/{}", sid);
+    auto const temporary_directory = ByteString::formatted("/tmp/session/{}", sid);
     auto directory = TRY(Core::Directory::create(temporary_directory, Core::Directory::CreateDirectories::Yes));
     TRY(directory.chown(uid, gid));
     return {};
diff --git a/Userland/Libraries/LibCore/SessionManagement.h b/Userland/Libraries/LibCore/SessionManagement.h
index 29eda5588b3..339280a7bfb 100644
--- a/Userland/Libraries/LibCore/SessionManagement.h
+++ b/Userland/Libraries/LibCore/SessionManagement.h
@@ -14,7 +14,7 @@ namespace Core::SessionManagement {
 ErrorOr<pid_t> root_session_id(Optional<pid_t> force_sid = {});
 ErrorOr<void> logout(Optional<pid_t> force_sid = {});
 
-ErrorOr<DeprecatedString> parse_path_with_sid(StringView general_path, Optional<pid_t> force_sid = {});
+ErrorOr<ByteString> parse_path_with_sid(StringView general_path, Optional<pid_t> force_sid = {});
 ErrorOr<void> create_session_temporary_directory_if_needed(uid_t uid, gid_t gid, Optional<pid_t> force_sid = {});
 
 }
diff --git a/Userland/Libraries/LibCore/SharedCircularQueue.h b/Userland/Libraries/LibCore/SharedCircularQueue.h
index b7ba276a394..e35b5fa83a5 100644
--- a/Userland/Libraries/LibCore/SharedCircularQueue.h
+++ b/Userland/Libraries/LibCore/SharedCircularQueue.h
@@ -9,8 +9,8 @@
 #include <AK/Assertions.h>
 #include <AK/Atomic.h>
 #include <AK/BuiltinWrappers.h>
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Error.h>
 #include <AK/Format.h>
 #include <AK/Function.h>
@@ -200,7 +200,7 @@ private:
 
     static ErrorOr<SharedSingleProducerCircularQueue<T, Size>> create_internal(int fd, bool is_new)
     {
-        auto name = DeprecatedString::formatted("SharedSingleProducerCircularQueue@{:x}", fd);
+        auto name = ByteString::formatted("SharedSingleProducerCircularQueue@{:x}", fd);
         auto* raw_mapping = TRY(System::mmap(nullptr, sizeof(SharedMemorySPCQ), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0, 0, name));
         dbgln_if(SHARED_QUEUE_DEBUG, "successfully mmapped {} at {:p}", name, raw_mapping);
 
@@ -212,7 +212,7 @@ private:
         return SharedSingleProducerCircularQueue<T, Size> { move(name), adopt_ref(*new (nothrow) RefCountedSharedMemorySPCQ(shared_queue, fd)) };
     }
 
-    SharedSingleProducerCircularQueue(DeprecatedString name, RefPtr<RefCountedSharedMemorySPCQ> queue)
+    SharedSingleProducerCircularQueue(ByteString name, RefPtr<RefCountedSharedMemorySPCQ> queue)
         : m_queue(queue)
         , m_name(move(name))
     {
@@ -220,7 +220,7 @@ private:
 
     RefPtr<RefCountedSharedMemorySPCQ> m_queue;
 
-    DeprecatedString m_name {};
+    ByteString m_name {};
 };
 
 }
diff --git a/Userland/Libraries/LibCore/Socket.cpp b/Userland/Libraries/LibCore/Socket.cpp
index f0a3a641bc4..395c0ac0083 100644
--- a/Userland/Libraries/LibCore/Socket.cpp
+++ b/Userland/Libraries/LibCore/Socket.cpp
@@ -46,7 +46,7 @@ ErrorOr<int> Socket::create_fd(SocketDomain domain, SocketType type)
 #endif
 }
 
-ErrorOr<IPv4Address> Socket::resolve_host(DeprecatedString const& host, SocketType type)
+ErrorOr<IPv4Address> Socket::resolve_host(ByteString const& host, SocketType type)
 {
     int socket_type;
     switch (type) {
@@ -79,7 +79,7 @@ ErrorOr<IPv4Address> Socket::resolve_host(DeprecatedString const& host, SocketTy
     return Error::from_string_literal("Could not resolve to IPv4 address");
 }
 
-ErrorOr<void> Socket::connect_local(int fd, DeprecatedString const& path)
+ErrorOr<void> Socket::connect_local(int fd, ByteString const& path)
 {
     auto address = SocketAddress::local(path);
     auto maybe_sockaddr = address.to_sockaddr_un();
@@ -189,7 +189,7 @@ void PosixSocketHelper::setup_notifier()
         m_notifier = Core::Notifier::construct(m_fd, Core::Notifier::Type::Read);
 }
 
-ErrorOr<NonnullOwnPtr<TCPSocket>> TCPSocket::connect(DeprecatedString const& host, u16 port)
+ErrorOr<NonnullOwnPtr<TCPSocket>> TCPSocket::connect(ByteString const& host, u16 port)
 {
     auto ip_address = TRY(resolve_host(host, SocketType::Stream));
     return connect(SocketAddress { ip_address, port });
@@ -231,7 +231,7 @@ ErrorOr<size_t> PosixSocketHelper::pending_bytes() const
     return static_cast<size_t>(value);
 }
 
-ErrorOr<NonnullOwnPtr<UDPSocket>> UDPSocket::connect(DeprecatedString const& host, u16 port, Optional<Duration> timeout)
+ErrorOr<NonnullOwnPtr<UDPSocket>> UDPSocket::connect(ByteString const& host, u16 port, Optional<Duration> timeout)
 {
     auto ip_address = TRY(resolve_host(host, SocketType::Datagram));
     return connect(SocketAddress { ip_address, port }, timeout);
@@ -253,7 +253,7 @@ ErrorOr<NonnullOwnPtr<UDPSocket>> UDPSocket::connect(SocketAddress const& addres
     return socket;
 }
 
-ErrorOr<NonnullOwnPtr<LocalSocket>> LocalSocket::connect(DeprecatedString const& path, PreventSIGPIPE prevent_sigpipe)
+ErrorOr<NonnullOwnPtr<LocalSocket>> LocalSocket::connect(ByteString const& path, PreventSIGPIPE prevent_sigpipe)
 {
     auto socket = TRY(adopt_nonnull_own_or_enomem(new (nothrow) LocalSocket(prevent_sigpipe)));
 
diff --git a/Userland/Libraries/LibCore/Socket.h b/Userland/Libraries/LibCore/Socket.h
index 55e18cdaea7..c9b4622e17e 100644
--- a/Userland/Libraries/LibCore/Socket.h
+++ b/Userland/Libraries/LibCore/Socket.h
@@ -72,9 +72,9 @@ protected:
     static ErrorOr<int> create_fd(SocketDomain, SocketType);
     // FIXME: This will need to be updated when IPv6 socket arrives. Perhaps a
     //        base class for all address types is appropriate.
-    static ErrorOr<IPv4Address> resolve_host(DeprecatedString const&, SocketType);
+    static ErrorOr<IPv4Address> resolve_host(ByteString const&, SocketType);
 
-    static ErrorOr<void> connect_local(int fd, DeprecatedString const& path);
+    static ErrorOr<void> connect_local(int fd, ByteString const& path);
     static ErrorOr<void> connect_inet(int fd, SocketAddress const&);
 
     int default_flags() const
@@ -97,7 +97,7 @@ public:
     virtual bool is_connected() = 0;
     /// Reconnects the socket to the given host and port. Returns EALREADY if
     /// is_connected() is true.
-    virtual ErrorOr<void> reconnect(DeprecatedString const& host, u16 port) = 0;
+    virtual ErrorOr<void> reconnect(ByteString const& host, u16 port) = 0;
     /// Connects the socket to the given socket address (IP address + port).
     /// Returns EALREADY is_connected() is true.
     virtual ErrorOr<void> reconnect(SocketAddress const&) = 0;
@@ -154,7 +154,7 @@ private:
 
 class TCPSocket final : public Socket {
 public:
-    static ErrorOr<NonnullOwnPtr<TCPSocket>> connect(DeprecatedString const& host, u16 port);
+    static ErrorOr<NonnullOwnPtr<TCPSocket>> connect(ByteString const& host, u16 port);
     static ErrorOr<NonnullOwnPtr<TCPSocket>> connect(SocketAddress const& address);
     static ErrorOr<NonnullOwnPtr<TCPSocket>> adopt_fd(int fd);
 
@@ -215,7 +215,7 @@ private:
 
 class UDPSocket final : public Socket {
 public:
-    static ErrorOr<NonnullOwnPtr<UDPSocket>> connect(DeprecatedString const& host, u16 port, Optional<Duration> timeout = {});
+    static ErrorOr<NonnullOwnPtr<UDPSocket>> connect(ByteString const& host, u16 port, Optional<Duration> timeout = {});
     static ErrorOr<NonnullOwnPtr<UDPSocket>> connect(SocketAddress const& address, Optional<Duration> timeout = {});
 
     UDPSocket(UDPSocket&& other)
@@ -289,7 +289,7 @@ private:
 
 class LocalSocket final : public Socket {
 public:
-    static ErrorOr<NonnullOwnPtr<LocalSocket>> connect(DeprecatedString const& path, PreventSIGPIPE = PreventSIGPIPE::No);
+    static ErrorOr<NonnullOwnPtr<LocalSocket>> connect(ByteString const& path, PreventSIGPIPE = PreventSIGPIPE::No);
     static ErrorOr<NonnullOwnPtr<LocalSocket>> adopt_fd(int fd, PreventSIGPIPE = PreventSIGPIPE::No);
 
     LocalSocket(LocalSocket&& other)
@@ -450,7 +450,7 @@ using BufferedLocalSocket = BufferedSocket<LocalSocket>;
 template<SocketLike T>
 class BasicReusableSocket final : public ReusableSocket {
 public:
-    static ErrorOr<NonnullOwnPtr<BasicReusableSocket<T>>> connect(DeprecatedString const& host, u16 port)
+    static ErrorOr<NonnullOwnPtr<BasicReusableSocket<T>>> connect(ByteString const& host, u16 port)
     {
         return make<BasicReusableSocket<T>>(TRY(T::connect(host, port)));
     }
@@ -465,7 +465,7 @@ public:
         return m_socket.is_open();
     }
 
-    virtual ErrorOr<void> reconnect(DeprecatedString const& host, u16 port) override
+    virtual ErrorOr<void> reconnect(ByteString const& host, u16 port) override
     {
         if (is_connected())
             return Error::from_errno(EALREADY);
diff --git a/Userland/Libraries/LibCore/SocketAddress.h b/Userland/Libraries/LibCore/SocketAddress.h
index 48f7cb6426d..4e7d1e75595 100644
--- a/Userland/Libraries/LibCore/SocketAddress.h
+++ b/Userland/Libraries/LibCore/SocketAddress.h
@@ -38,7 +38,7 @@ public:
     {
     }
 
-    static SocketAddress local(DeprecatedString const& address)
+    static SocketAddress local(ByteString const& address)
     {
         SocketAddress addr;
         addr.m_type = Type::Local;
@@ -51,11 +51,11 @@ public:
     IPv4Address ipv4_address() const { return m_ipv4_address; }
     u16 port() const { return m_port; }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
         switch (m_type) {
         case Type::IPv4:
-            return DeprecatedString::formatted("{}:{}", m_ipv4_address, m_port);
+            return ByteString::formatted("{}:{}", m_ipv4_address, m_port);
         case Type::Local:
             return m_local_address;
         default:
@@ -91,16 +91,16 @@ private:
     Type m_type { Type::Invalid };
     IPv4Address m_ipv4_address;
     u16 m_port { 0 };
-    DeprecatedString m_local_address;
+    ByteString m_local_address;
 };
 
 }
 
 template<>
-struct AK::Formatter<Core::SocketAddress> : Formatter<DeprecatedString> {
+struct AK::Formatter<Core::SocketAddress> : Formatter<ByteString> {
     ErrorOr<void> format(FormatBuilder& builder, Core::SocketAddress const& value)
     {
-        return Formatter<DeprecatedString>::format(builder, value.to_deprecated_string());
+        return Formatter<ByteString>::format(builder, value.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibCore/StandardPaths.cpp b/Userland/Libraries/LibCore/StandardPaths.cpp
index b25eb8ee9be..f6dce7c023b 100644
--- a/Userland/Libraries/LibCore/StandardPaths.cpp
+++ b/Userland/Libraries/LibCore/StandardPaths.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/Platform.h>
 #include <AK/String.h>
@@ -22,42 +22,42 @@
 
 namespace Core {
 
-DeprecatedString StandardPaths::home_directory()
+ByteString StandardPaths::home_directory()
 {
     if (auto* home_env = getenv("HOME"))
         return LexicalPath::canonicalized_path(home_env);
 
     auto* pwd = getpwuid(getuid());
-    DeprecatedString path = pwd ? pwd->pw_dir : "/";
+    ByteString path = pwd ? pwd->pw_dir : "/";
     endpwent();
     return LexicalPath::canonicalized_path(path);
 }
 
-DeprecatedString StandardPaths::desktop_directory()
+ByteString StandardPaths::desktop_directory()
 {
     StringBuilder builder;
     builder.append(home_directory());
     builder.append("/Desktop"sv);
-    return LexicalPath::canonicalized_path(builder.to_deprecated_string());
+    return LexicalPath::canonicalized_path(builder.to_byte_string());
 }
 
-DeprecatedString StandardPaths::documents_directory()
+ByteString StandardPaths::documents_directory()
 {
     StringBuilder builder;
     builder.append(home_directory());
     builder.append("/Documents"sv);
-    return LexicalPath::canonicalized_path(builder.to_deprecated_string());
+    return LexicalPath::canonicalized_path(builder.to_byte_string());
 }
 
-DeprecatedString StandardPaths::downloads_directory()
+ByteString StandardPaths::downloads_directory()
 {
     StringBuilder builder;
     builder.append(home_directory());
     builder.append("/Downloads"sv);
-    return LexicalPath::canonicalized_path(builder.to_deprecated_string());
+    return LexicalPath::canonicalized_path(builder.to_byte_string());
 }
 
-DeprecatedString StandardPaths::config_directory()
+ByteString StandardPaths::config_directory()
 {
     if (auto* config_directory = getenv("XDG_CONFIG_HOME"))
         return LexicalPath::canonicalized_path(config_directory);
@@ -71,10 +71,10 @@ DeprecatedString StandardPaths::config_directory()
 #else
     builder.append("/.config"sv);
 #endif
-    return LexicalPath::canonicalized_path(builder.to_deprecated_string());
+    return LexicalPath::canonicalized_path(builder.to_byte_string());
 }
 
-DeprecatedString StandardPaths::data_directory()
+ByteString StandardPaths::data_directory()
 {
     if (auto* data_directory = getenv("XDG_DATA_HOME"))
         return LexicalPath::canonicalized_path(data_directory);
@@ -91,10 +91,10 @@ DeprecatedString StandardPaths::data_directory()
     builder.append("/.local/share"sv);
 #endif
 
-    return LexicalPath::canonicalized_path(builder.to_deprecated_string());
+    return LexicalPath::canonicalized_path(builder.to_byte_string());
 }
 
-ErrorOr<DeprecatedString> StandardPaths::runtime_directory()
+ErrorOr<ByteString> StandardPaths::runtime_directory()
 {
     if (auto* data_directory = getenv("XDG_RUNTIME_DIR"))
         return LexicalPath::canonicalized_path(data_directory);
@@ -114,10 +114,10 @@ ErrorOr<DeprecatedString> StandardPaths::runtime_directory()
     builder.appendff("/run/user/{}", uid);
 #endif
 
-    return LexicalPath::canonicalized_path(builder.to_deprecated_string());
+    return LexicalPath::canonicalized_path(builder.to_byte_string());
 }
 
-DeprecatedString StandardPaths::tempfile_directory()
+ByteString StandardPaths::tempfile_directory()
 {
     return "/tmp";
 }
diff --git a/Userland/Libraries/LibCore/StandardPaths.h b/Userland/Libraries/LibCore/StandardPaths.h
index 470438c62d5..5791f8fadfa 100644
--- a/Userland/Libraries/LibCore/StandardPaths.h
+++ b/Userland/Libraries/LibCore/StandardPaths.h
@@ -14,14 +14,14 @@ namespace Core {
 
 class StandardPaths {
 public:
-    static DeprecatedString home_directory();
-    static DeprecatedString desktop_directory();
-    static DeprecatedString documents_directory();
-    static DeprecatedString downloads_directory();
-    static DeprecatedString tempfile_directory();
-    static DeprecatedString config_directory();
-    static DeprecatedString data_directory();
-    static ErrorOr<DeprecatedString> runtime_directory();
+    static ByteString home_directory();
+    static ByteString desktop_directory();
+    static ByteString documents_directory();
+    static ByteString downloads_directory();
+    static ByteString tempfile_directory();
+    static ByteString config_directory();
+    static ByteString data_directory();
+    static ErrorOr<ByteString> runtime_directory();
     static ErrorOr<Vector<String>> font_directories();
 };
 
diff --git a/Userland/Libraries/LibCore/System.cpp b/Userland/Libraries/LibCore/System.cpp
index f7de49ee62f..ab49f2cadf3 100644
--- a/Userland/Libraries/LibCore/System.cpp
+++ b/Userland/Libraries/LibCore/System.cpp
@@ -7,7 +7,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/FixedArray.h>
 #include <AK/ScopeGuard.h>
 #include <AK/ScopedValueRollback.h>
@@ -202,7 +202,7 @@ ErrorOr<void> unveil(StringView path, StringView permissions)
         { nullptr, 0 },
     };
 
-    DeprecatedString parsed_path;
+    ByteString parsed_path;
     if (!path.is_null()) {
         parsed_path = TRY(Core::SessionManagement::parse_path_with_sid(path));
         params.path = { parsed_path.characters(), parsed_path.length() };
@@ -215,7 +215,7 @@ ErrorOr<void> unveil(StringView path, StringView permissions)
 
 ErrorOr<void> unveil_after_exec(StringView path, StringView permissions)
 {
-    DeprecatedString parsed_path;
+    ByteString parsed_path;
     Syscall::SC_unveil_params params {
         static_cast<int>(UnveilFlags::AfterExec),
         { nullptr, 0 },
@@ -448,7 +448,7 @@ ErrorOr<struct stat> fstatat(int fd, StringView path, int flags)
     Syscall::SC_stat_params params { { path.characters_without_null_termination(), path.length() }, &st, fd, !(flags & AT_SYMLINK_NOFOLLOW) };
     int rc = syscall(SC_stat, &params);
 #else
-    DeprecatedString path_string = path;
+    ByteString path_string = path;
     int rc = ::fstatat(fd, path_string.characters(), &st, flags);
 #endif
     HANDLE_SYSCALL_RETURN_VALUE("fstatat", rc, st);
@@ -531,7 +531,7 @@ ErrorOr<int> anon_create([[maybe_unused]] size_t size, [[maybe_unused]] int opti
 #elif defined(AK_OS_BSD_GENERIC) || defined(AK_OS_EMSCRIPTEN) || defined(AK_OS_HAIKU)
     struct timespec time;
     clock_gettime(CLOCK_REALTIME, &time);
-    auto name = DeprecatedString::formatted("/shm-{}{}", (unsigned long)time.tv_sec, (unsigned long)time.tv_nsec);
+    auto name = ByteString::formatted("/shm-{}{}", (unsigned long)time.tv_sec, (unsigned long)time.tv_nsec);
     fd = shm_open(name.characters(), O_RDWR | O_CREAT | options, 0600);
 
     if (shm_unlink(name.characters()) == -1) {
@@ -576,7 +576,7 @@ ErrorOr<int> openat(int fd, StringView path, int options, mode_t mode)
     HANDLE_SYSCALL_RETURN_VALUE("open", rc, rc);
 #else
     // NOTE: We have to ensure that the path is null-terminated.
-    DeprecatedString path_string = path;
+    ByteString path_string = path;
     int rc = ::openat(fd, path_string.characters(), options, mode);
     if (rc < 0)
         return Error::from_syscall("open"sv, -errno);
@@ -609,7 +609,7 @@ ErrorOr<struct stat> stat(StringView path)
     int rc = syscall(SC_stat, &params);
     HANDLE_SYSCALL_RETURN_VALUE("stat", rc, st);
 #else
-    DeprecatedString path_string = path;
+    ByteString path_string = path;
     if (::stat(path_string.characters(), &st) < 0)
         return Error::from_syscall("stat"sv, -errno);
     return st;
@@ -627,7 +627,7 @@ ErrorOr<struct stat> lstat(StringView path)
     int rc = syscall(SC_stat, &params);
     HANDLE_SYSCALL_RETURN_VALUE("lstat", rc, st);
 #else
-    DeprecatedString path_string = path;
+    ByteString path_string = path;
     if (::lstat(path_string.characters(), &st) < 0)
         return Error::from_syscall("lstat"sv, -errno);
     return st;
@@ -680,21 +680,21 @@ ErrorOr<int> dup2(int source_fd, int destination_fd)
     return fd;
 }
 
-ErrorOr<DeprecatedString> ptsname(int fd)
+ErrorOr<ByteString> ptsname(int fd)
 {
     auto* name = ::ptsname(fd);
     if (!name)
         return Error::from_syscall("ptsname"sv, -errno);
-    return DeprecatedString(name);
+    return ByteString(name);
 }
 
-ErrorOr<DeprecatedString> gethostname()
+ErrorOr<ByteString> gethostname()
 {
     char hostname[HOST_NAME_MAX];
     int rc = ::gethostname(hostname, sizeof(hostname));
     if (rc < 0)
         return Error::from_syscall("gethostname"sv, -errno);
-    return DeprecatedString(&hostname[0]);
+    return ByteString(&hostname[0]);
 }
 
 ErrorOr<void> sethostname(StringView hostname)
@@ -709,13 +709,13 @@ ErrorOr<void> sethostname(StringView hostname)
     return {};
 }
 
-ErrorOr<DeprecatedString> getcwd()
+ErrorOr<ByteString> getcwd()
 {
     auto* cwd = ::getcwd(nullptr, 0);
     if (!cwd)
         return Error::from_syscall("getcwd"sv, -errno);
 
-    DeprecatedString string_cwd(cwd);
+    ByteString string_cwd(cwd);
     free(cwd);
     return string_cwd;
 }
@@ -773,7 +773,7 @@ ErrorOr<void> chmod(StringView pathname, mode_t mode)
     int rc = syscall(SC_chmod, &params);
     HANDLE_SYSCALL_RETURN_VALUE("chmod", rc, {});
 #else
-    DeprecatedString path = pathname;
+    ByteString path = pathname;
     if (::chmod(path.characters(), mode) < 0)
         return Error::from_syscall("chmod"sv, -errno);
     return {};
@@ -804,7 +804,7 @@ ErrorOr<void> lchown(StringView pathname, uid_t uid, gid_t gid)
     int rc = syscall(SC_chown, &params);
     HANDLE_SYSCALL_RETURN_VALUE("chown", rc, {});
 #else
-    DeprecatedString path = pathname;
+    ByteString path = pathname;
     if (::chown(path.characters(), uid, gid) < 0)
         return Error::from_syscall("chown"sv, -errno);
     return {};
@@ -821,7 +821,7 @@ ErrorOr<void> chown(StringView pathname, uid_t uid, gid_t gid)
     int rc = syscall(SC_chown, &params);
     HANDLE_SYSCALL_RETURN_VALUE("chown", rc, {});
 #else
-    DeprecatedString path = pathname;
+    ByteString path = pathname;
     if (::lchown(path.characters(), uid, gid) < 0)
         return Error::from_syscall("lchown"sv, -errno);
     return {};
@@ -913,7 +913,7 @@ ErrorOr<void> clock_settime(clockid_t clock_id, struct timespec* ts)
 static ALWAYS_INLINE ErrorOr<pid_t> posix_spawn_wrapper(StringView path, posix_spawn_file_actions_t const* file_actions, posix_spawnattr_t const* attr, char* const arguments[], char* const envp[], StringView function_name, decltype(::posix_spawn) spawn_function)
 {
     pid_t child_pid;
-    if ((errno = spawn_function(&child_pid, path.to_deprecated_string().characters(), file_actions, attr, arguments, envp)))
+    if ((errno = spawn_function(&child_pid, path.to_byte_string().characters(), file_actions, attr, arguments, envp)))
         return Error::from_syscall(function_name, -errno);
     return child_pid;
 }
@@ -1036,8 +1036,8 @@ ErrorOr<void> link(StringView old_path, StringView new_path)
     int rc = syscall(SC_link, &params);
     HANDLE_SYSCALL_RETURN_VALUE("link", rc, {});
 #else
-    DeprecatedString old_path_string = old_path;
-    DeprecatedString new_path_string = new_path;
+    ByteString old_path_string = old_path;
+    ByteString new_path_string = new_path;
     if (::link(old_path_string.characters(), new_path_string.characters()) < 0)
         return Error::from_syscall("link"sv, -errno);
     return {};
@@ -1055,8 +1055,8 @@ ErrorOr<void> symlink(StringView target, StringView link_path)
     int rc = syscall(SC_symlink, &params);
     HANDLE_SYSCALL_RETURN_VALUE("symlink", rc, {});
 #else
-    DeprecatedString target_string = target;
-    DeprecatedString link_path_string = link_path;
+    ByteString target_string = target;
+    ByteString link_path_string = link_path;
     if (::symlink(target_string.characters(), link_path_string.characters()) < 0)
         return Error::from_syscall("symlink"sv, -errno);
     return {};
@@ -1071,7 +1071,7 @@ ErrorOr<void> mkdir(StringView path, mode_t mode)
     int rc = syscall(SC_mkdir, AT_FDCWD, path.characters_without_null_termination(), path.length(), mode);
     HANDLE_SYSCALL_RETURN_VALUE("mkdir", rc, {});
 #else
-    DeprecatedString path_string = path;
+    ByteString path_string = path;
     if (::mkdir(path_string.characters(), mode) < 0)
         return Error::from_syscall("mkdir"sv, -errno);
     return {};
@@ -1086,7 +1086,7 @@ ErrorOr<void> chdir(StringView path)
     int rc = syscall(SC_chdir, path.characters_without_null_termination(), path.length());
     HANDLE_SYSCALL_RETURN_VALUE("chdir", rc, {});
 #else
-    DeprecatedString path_string = path;
+    ByteString path_string = path;
     if (::chdir(path_string.characters()) < 0)
         return Error::from_syscall("chdir"sv, -errno);
     return {};
@@ -1101,7 +1101,7 @@ ErrorOr<void> rmdir(StringView path)
     int rc = syscall(SC_rmdir, path.characters_without_null_termination(), path.length());
     HANDLE_SYSCALL_RETURN_VALUE("rmdir", rc, {});
 #else
-    DeprecatedString path_string = path;
+    ByteString path_string = path;
     if (::rmdir(path_string.characters()) < 0)
         return Error::from_syscall("rmdir"sv, -errno);
     return {};
@@ -1149,8 +1149,8 @@ ErrorOr<void> rename(StringView old_path, StringView new_path)
     int rc = syscall(SC_rename, &params);
     HANDLE_SYSCALL_RETURN_VALUE("rename", rc, {});
 #else
-    DeprecatedString old_path_string = old_path;
-    DeprecatedString new_path_string = new_path;
+    ByteString old_path_string = old_path;
+    ByteString new_path_string = new_path;
     if (::rename(old_path_string.characters(), new_path_string.characters()) < 0)
         return Error::from_syscall("rename"sv, -errno);
     return {};
@@ -1166,7 +1166,7 @@ ErrorOr<void> unlink(StringView path)
     int rc = syscall(SC_unlink, AT_FDCWD, path.characters_without_null_termination(), path.length(), 0);
     HANDLE_SYSCALL_RETURN_VALUE("unlink", rc, {});
 #else
-    DeprecatedString path_string = path;
+    ByteString path_string = path;
     if (::unlink(path_string.characters()) < 0)
         return Error::from_syscall("unlink"sv, -errno);
     return {};
@@ -1185,7 +1185,7 @@ ErrorOr<void> utime(StringView path, Optional<struct utimbuf> maybe_buf)
     int rc = syscall(SC_utime, path.characters_without_null_termination(), path.length(), buf);
     HANDLE_SYSCALL_RETURN_VALUE("utime", rc, {});
 #else
-    DeprecatedString path_string = path;
+    ByteString path_string = path;
     if (::utime(path_string.characters(), buf) < 0)
         return Error::from_syscall("utime"sv, -errno);
     return {};
@@ -1364,22 +1364,22 @@ ErrorOr<void> exec(StringView filename, ReadonlySpan<StringView> arguments, Sear
     TRY(run_exec(params));
     VERIFY_NOT_REACHED();
 #else
-    DeprecatedString filename_string { filename };
+    ByteString filename_string { filename };
 
-    auto argument_strings = TRY(FixedArray<DeprecatedString>::create(arguments.size()));
+    auto argument_strings = TRY(FixedArray<ByteString>::create(arguments.size()));
     auto argv = TRY(FixedArray<char*>::create(arguments.size() + 1));
     for (size_t i = 0; i < arguments.size(); ++i) {
-        argument_strings[i] = arguments[i].to_deprecated_string();
+        argument_strings[i] = arguments[i].to_byte_string();
         argv[i] = const_cast<char*>(argument_strings[i].characters());
     }
     argv[arguments.size()] = nullptr;
 
     int rc = 0;
     if (environment.has_value()) {
-        auto environment_strings = TRY(FixedArray<DeprecatedString>::create(environment->size()));
+        auto environment_strings = TRY(FixedArray<ByteString>::create(environment->size()));
         auto envp = TRY(FixedArray<char*>::create(environment->size() + 1));
         for (size_t i = 0; i < environment->size(); ++i) {
-            environment_strings[i] = environment->at(i).to_deprecated_string();
+            environment_strings[i] = environment->at(i).to_byte_string();
             envp[i] = const_cast<char*>(environment_strings[i].characters());
         }
         envp[environment->size()] = nullptr;
@@ -1396,7 +1396,7 @@ ErrorOr<void> exec(StringView filename, ReadonlySpan<StringView> arguments, Sear
                 return executable_or_error.release_error();
             }
 
-            DeprecatedString executable = executable_or_error.release_value().to_deprecated_string();
+            ByteString executable = executable_or_error.release_value().to_byte_string();
             rc = ::execve(executable.characters(), argv.data(), envp.data());
 #    else
             rc = ::execvpe(filename_string.characters(), argv.data(), envp.data());
@@ -1611,7 +1611,7 @@ ErrorOr<void> mknod(StringView pathname, mode_t mode, dev_t dev)
     int rc = syscall(SC_mknod, &params);
     HANDLE_SYSCALL_RETURN_VALUE("mknod", rc, {});
 #else
-    DeprecatedString path_string = pathname;
+    ByteString path_string = pathname;
     if (::mknod(path_string.characters(), mode, dev) < 0)
         return Error::from_syscall("mknod"sv, -errno);
     return {};
@@ -1705,7 +1705,7 @@ ErrorOr<void> access(StringView pathname, int mode, int flags)
     int rc = ::syscall(Syscall::SC_faccessat, &params);
     HANDLE_SYSCALL_RETURN_VALUE("access", rc, {});
 #else
-    DeprecatedString path_string = pathname;
+    ByteString path_string = pathname;
     (void)flags;
     if (::access(path_string.characters(), mode) < 0)
         return Error::from_syscall("access"sv, -errno);
@@ -1713,7 +1713,7 @@ ErrorOr<void> access(StringView pathname, int mode, int flags)
 #endif
 }
 
-ErrorOr<DeprecatedString> readlink(StringView pathname)
+ErrorOr<ByteString> readlink(StringView pathname)
 {
     // FIXME: Try again with a larger buffer.
 #ifdef AK_OS_SERENITY
@@ -1724,7 +1724,7 @@ ErrorOr<DeprecatedString> readlink(StringView pathname)
         .dirfd = AT_FDCWD,
     };
     int rc = syscall(SC_readlink, &small_params);
-    HANDLE_SYSCALL_RETURN_VALUE("readlink", rc, DeprecatedString(data, rc));
+    HANDLE_SYSCALL_RETURN_VALUE("readlink", rc, ByteString(data, rc));
 #elif defined(AK_OS_GNU_HURD)
     // PATH_MAX is not defined, nor is there an upper limit on path lengths.
     // Let's do this the right way.
@@ -1732,15 +1732,15 @@ ErrorOr<DeprecatedString> readlink(StringView pathname)
     auto file = TRY(File::adopt_fd(fd, File::OpenMode::Read));
     auto buffer = TRY(file->read_until_eof());
     // TODO: Get rid of this copy here.
-    return DeprecatedString::copy(buffer);
+    return ByteString::copy(buffer);
 #else
     char data[PATH_MAX];
-    DeprecatedString path_string = pathname;
+    ByteString path_string = pathname;
     int rc = ::readlink(path_string.characters(), data, sizeof(data));
     if (rc == -1)
         return Error::from_syscall("readlink"sv, -errno);
 
-    return DeprecatedString(data, rc);
+    return ByteString(data, rc);
 #endif
 }
 
@@ -1806,7 +1806,7 @@ char** environment()
 #endif
 }
 
-ErrorOr<DeprecatedString> current_executable_path()
+ErrorOr<ByteString> current_executable_path()
 {
     char path[4096] = {};
 #if defined(AK_OS_LINUX) || defined(AK_OS_ANDROID) || defined(AK_OS_SERENITY)
@@ -1862,7 +1862,7 @@ ErrorOr<DeprecatedString> current_executable_path()
     return Error::from_string_view("current_executable_path unknown"sv);
 #endif
     path[sizeof(path) - 1] = '\0';
-    return DeprecatedString { path, strlen(path) };
+    return ByteString { path, strlen(path) };
 }
 
 ErrorOr<Bytes> allocate(size_t count, size_t size)
diff --git a/Userland/Libraries/LibCore/System.h b/Userland/Libraries/LibCore/System.h
index c170adbbb13..70e350eacda 100644
--- a/Userland/Libraries/LibCore/System.h
+++ b/Userland/Libraries/LibCore/System.h
@@ -135,10 +135,10 @@ ErrorOr<void> kill(pid_t, int signal);
 ErrorOr<void> killpg(int pgrp, int signal);
 ErrorOr<int> dup(int source_fd);
 ErrorOr<int> dup2(int source_fd, int destination_fd);
-ErrorOr<DeprecatedString> ptsname(int fd);
-ErrorOr<DeprecatedString> gethostname();
+ErrorOr<ByteString> ptsname(int fd);
+ErrorOr<ByteString> gethostname();
 ErrorOr<void> sethostname(StringView);
-ErrorOr<DeprecatedString> getcwd();
+ErrorOr<ByteString> getcwd();
 ErrorOr<void> ioctl(int fd, unsigned request, ...);
 ErrorOr<struct termios> tcgetattr(int fd);
 ErrorOr<void> tcsetattr(int fd, int optional_actions, struct termios const&);
@@ -235,7 +235,7 @@ ErrorOr<int> posix_openpt(int flags);
 ErrorOr<void> grantpt(int fildes);
 ErrorOr<void> unlockpt(int fildes);
 ErrorOr<void> access(StringView pathname, int mode, int flags = 0);
-ErrorOr<DeprecatedString> readlink(StringView pathname);
+ErrorOr<ByteString> readlink(StringView pathname);
 ErrorOr<int> poll(Span<struct pollfd>, int timeout);
 
 #ifdef AK_OS_SERENITY
@@ -279,7 +279,7 @@ ErrorOr<String> resolve_executable_from_environment(StringView filename, int fla
 
 char** environment();
 
-ErrorOr<DeprecatedString> current_executable_path();
+ErrorOr<ByteString> current_executable_path();
 
 ErrorOr<Bytes> allocate(size_t count, size_t size);
 
diff --git a/Userland/Libraries/LibCore/SystemServerTakeover.cpp b/Userland/Libraries/LibCore/SystemServerTakeover.cpp
index d15f52fb845..357f6f3bf77 100644
--- a/Userland/Libraries/LibCore/SystemServerTakeover.cpp
+++ b/Userland/Libraries/LibCore/SystemServerTakeover.cpp
@@ -10,7 +10,7 @@
 
 namespace Core {
 
-HashMap<DeprecatedString, int> s_overtaken_sockets {};
+HashMap<ByteString, int> s_overtaken_sockets {};
 bool s_overtaken_sockets_parsed { false };
 
 static void parse_sockets_from_system_server()
@@ -27,7 +27,7 @@ static void parse_sockets_from_system_server()
     for (auto const socket : StringView { sockets, strlen(sockets) }.split_view(';')) {
         auto params = socket.split_view(':');
         VERIFY(params.size() == 2);
-        s_overtaken_sockets.set(params[0].to_deprecated_string(), params[1].to_int().value());
+        s_overtaken_sockets.set(params[0].to_byte_string(), params[1].to_int().value());
     }
 
     s_overtaken_sockets_parsed = true;
@@ -36,7 +36,7 @@ static void parse_sockets_from_system_server()
     unsetenv(socket_takeover);
 }
 
-ErrorOr<NonnullOwnPtr<Core::LocalSocket>> take_over_socket_from_system_server(DeprecatedString const& socket_path)
+ErrorOr<NonnullOwnPtr<Core::LocalSocket>> take_over_socket_from_system_server(ByteString const& socket_path)
 {
     if (!s_overtaken_sockets_parsed)
         parse_sockets_from_system_server();
diff --git a/Userland/Libraries/LibCore/SystemServerTakeover.h b/Userland/Libraries/LibCore/SystemServerTakeover.h
index fb1fa97dbb0..0a1bdae0387 100644
--- a/Userland/Libraries/LibCore/SystemServerTakeover.h
+++ b/Userland/Libraries/LibCore/SystemServerTakeover.h
@@ -10,6 +10,6 @@
 
 namespace Core {
 
-ErrorOr<NonnullOwnPtr<Core::LocalSocket>> take_over_socket_from_system_server(DeprecatedString const& socket_path = {});
+ErrorOr<NonnullOwnPtr<Core::LocalSocket>> take_over_socket_from_system_server(ByteString const& socket_path = {});
 
 }
diff --git a/Userland/Libraries/LibCoredump/Backtrace.cpp b/Userland/Libraries/LibCoredump/Backtrace.cpp
index 3bdbc5c1174..d8064529eac 100644
--- a/Userland/Libraries/LibCoredump/Backtrace.cpp
+++ b/Userland/Libraries/LibCoredump/Backtrace.cpp
@@ -20,7 +20,7 @@ namespace Coredump {
 
 ELFObjectInfo const* Backtrace::object_info_for_region(Reader const& coredump, MemoryRegionInfo const& region)
 {
-    DeprecatedString path = coredump.resolve_object_path(region.object_name());
+    ByteString path = coredump.resolve_object_path(region.object_name());
 
     auto maybe_ptr = m_debug_info_cache.get(path);
     if (maybe_ptr.has_value())
@@ -127,13 +127,13 @@ void Backtrace::add_entry(Reader const& coredump, FlatPtr ip)
     m_entries.append({ ip, object_name, function_name, source_position });
 }
 
-DeprecatedString Backtrace::Entry::to_deprecated_string(bool color) const
+ByteString Backtrace::Entry::to_byte_string(bool color) const
 {
     StringBuilder builder;
     builder.appendff("{:p}: ", eip);
     if (object_name.is_empty()) {
         builder.append("???"sv);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
     builder.appendff("[{}] {}", object_name, function_name.is_empty() ? "???" : function_name);
     builder.append(" ("sv);
@@ -160,7 +160,7 @@ DeprecatedString Backtrace::Entry::to_deprecated_string(bool color) const
 
     builder.append(')');
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/Userland/Libraries/LibCoredump/Backtrace.h b/Userland/Libraries/LibCoredump/Backtrace.h
index 598cecccec2..6c22776d574 100644
--- a/Userland/Libraries/LibCoredump/Backtrace.h
+++ b/Userland/Libraries/LibCoredump/Backtrace.h
@@ -31,11 +31,11 @@ class Backtrace {
 public:
     struct Entry {
         FlatPtr eip;
-        DeprecatedString object_name;
-        DeprecatedString function_name;
+        ByteString object_name;
+        ByteString function_name;
         Debug::DebugInfo::SourcePositionWithInlines source_position_with_inlines;
 
-        DeprecatedString to_deprecated_string(bool color = false) const;
+        ByteString to_byte_string(bool color = false) const;
     };
 
     Backtrace(Reader const&, const ELF::Core::ThreadInfo&, Function<void(size_t, size_t)> on_progress = {});
@@ -51,7 +51,7 @@ private:
     bool m_skip_loader_so { false };
     ELF::Core::ThreadInfo m_thread_info;
     Vector<Entry> m_entries;
-    HashMap<DeprecatedString, NonnullOwnPtr<ELFObjectInfo>> m_debug_info_cache;
+    HashMap<ByteString, NonnullOwnPtr<ELFObjectInfo>> m_debug_info_cache;
 };
 
 }
diff --git a/Userland/Libraries/LibCoredump/Inspector.cpp b/Userland/Libraries/LibCoredump/Inspector.cpp
index bad065ab632..d9d4423fa77 100644
--- a/Userland/Libraries/LibCoredump/Inspector.cpp
+++ b/Userland/Libraries/LibCoredump/Inspector.cpp
@@ -46,7 +46,7 @@ void Inspector::parse_loaded_libraries(Function<void(float)> on_progress)
             return;
 
         auto image = make<ELF::Image>(file_or_error.value()->bytes());
-        auto debug_info = make<Debug::DebugInfo>(*image, DeprecatedString {}, library.base_address);
+        auto debug_info = make<Debug::DebugInfo>(*image, ByteString {}, library.base_address);
         m_loaded_libraries.append(make<Debug::LoadedLibrary>(library.name, file_or_error.release_value(), move(image), move(debug_info), library.base_address));
     });
 }
diff --git a/Userland/Libraries/LibCoredump/Reader.cpp b/Userland/Libraries/LibCoredump/Reader.cpp
index 42ffb597ac8..293f48b3552 100644
--- a/Userland/Libraries/LibCoredump/Reader.cpp
+++ b/Userland/Libraries/LibCoredump/Reader.cpp
@@ -210,20 +210,20 @@ u8 Reader::process_termination_signal() const
     return *termination_signal;
 }
 
-DeprecatedString Reader::process_executable_path() const
+ByteString Reader::process_executable_path() const
 {
     auto process_info = this->process_info();
-    auto executable_path = process_info.get_deprecated_string("executable_path"sv);
+    auto executable_path = process_info.get_byte_string("executable_path"sv);
     return executable_path.value_or({});
 }
 
-Vector<DeprecatedString> Reader::process_arguments() const
+Vector<ByteString> Reader::process_arguments() const
 {
     auto process_info = this->process_info();
     auto arguments = process_info.get_array("arguments"sv);
     if (!arguments.has_value())
         return {};
-    Vector<DeprecatedString> vector;
+    Vector<ByteString> vector;
     arguments->for_each([&](auto& value) {
         if (value.is_string())
             vector.append(value.as_string());
@@ -231,13 +231,13 @@ Vector<DeprecatedString> Reader::process_arguments() const
     return vector;
 }
 
-Vector<DeprecatedString> Reader::process_environment() const
+Vector<ByteString> Reader::process_environment() const
 {
     auto process_info = this->process_info();
     auto environment = process_info.get_array("environment"sv);
     if (!environment.has_value())
         return {};
-    Vector<DeprecatedString> vector;
+    Vector<ByteString> vector;
     environment->for_each([&](auto& value) {
         if (value.is_string())
             vector.append(value.as_string());
@@ -245,7 +245,7 @@ Vector<DeprecatedString> Reader::process_environment() const
     return vector;
 }
 
-HashMap<DeprecatedString, DeprecatedString> Reader::metadata() const
+HashMap<ByteString, ByteString> Reader::metadata() const
 {
     const ELF::Core::Metadata* metadata_notes_entry = nullptr;
     NotesEntryIterator it(bit_cast<u8 const*>(m_coredump_image.program_header(m_notes_segment_index).raw_data()));
@@ -263,7 +263,7 @@ HashMap<DeprecatedString, DeprecatedString> Reader::metadata() const
         return {};
     if (!metadata_json_value.value().is_object())
         return {};
-    HashMap<DeprecatedString, DeprecatedString> metadata;
+    HashMap<ByteString, ByteString> metadata;
     metadata_json_value.value().as_object().for_each_member([&](auto& key, auto& value) {
         metadata.set(key, value.as_string_or({}));
     });
@@ -272,13 +272,13 @@ HashMap<DeprecatedString, DeprecatedString> Reader::metadata() const
 
 Reader::LibraryData const* Reader::library_containing(FlatPtr address) const
 {
-    static HashMap<DeprecatedString, OwnPtr<LibraryData>> cached_libs;
+    static HashMap<ByteString, OwnPtr<LibraryData>> cached_libs;
     auto region = region_containing(address);
     if (!region.has_value())
         return {};
 
     auto name = region->object_name();
-    DeprecatedString path = resolve_object_path(name);
+    ByteString path = resolve_object_path(name);
 
     if (!cached_libs.contains(path)) {
         auto file_or_error = Core::MappedFile::map(path);
@@ -292,7 +292,7 @@ Reader::LibraryData const* Reader::library_containing(FlatPtr address) const
     return lib_data;
 }
 
-DeprecatedString Reader::resolve_object_path(StringView name) const
+ByteString Reader::resolve_object_path(StringView name) const
 {
     // TODO: There are other places where similar method is implemented or would be useful.
     //       (e.g. UserspaceEmulator, LibSymbolication, Profiler, and DynamicLinker itself)
@@ -302,7 +302,7 @@ DeprecatedString Reader::resolve_object_path(StringView name) const
         return name;
     }
 
-    Vector<DeprecatedString> library_search_directories;
+    Vector<ByteString> library_search_directories;
 
     // If LD_LIBRARY_PATH is present, check its folders first
     for (auto& environment_variable : process_environment()) {
@@ -336,7 +336,7 @@ DeprecatedString Reader::resolve_object_path(StringView name) const
 
 void Reader::for_each_library(Function<void(LibraryInfo)> func) const
 {
-    HashTable<DeprecatedString> libraries;
+    HashTable<ByteString> libraries;
     for_each_memory_region_info([&](auto const& region) {
         auto name = region.object_name();
         if (name.is_null() || libraries.contains(name))
@@ -344,7 +344,7 @@ void Reader::for_each_library(Function<void(LibraryInfo)> func) const
 
         libraries.set(name);
 
-        DeprecatedString path = resolve_object_path(name);
+        ByteString path = resolve_object_path(name);
 
         func(LibraryInfo { name, path, static_cast<FlatPtr>(region.region_start) });
         return IterationDecision::Continue;
diff --git a/Userland/Libraries/LibCoredump/Reader.h b/Userland/Libraries/LibCoredump/Reader.h
index 959c8f8c74e..7c5be3544ad 100644
--- a/Userland/Libraries/LibCoredump/Reader.h
+++ b/Userland/Libraries/LibCoredump/Reader.h
@@ -47,8 +47,8 @@ public:
     void for_each_memory_region_info(Func func) const;
 
     struct LibraryInfo {
-        DeprecatedString name;
-        DeprecatedString path;
+        ByteString name;
+        ByteString path;
         FlatPtr base_address { 0 };
     };
 
@@ -64,21 +64,21 @@ public:
     Optional<MemoryRegionInfo> region_containing(FlatPtr address) const;
 
     struct LibraryData {
-        DeprecatedString name;
+        ByteString name;
         FlatPtr base_address { 0 };
         NonnullOwnPtr<Core::MappedFile> file;
         ELF::Image lib_elf;
     };
     LibraryData const* library_containing(FlatPtr address) const;
 
-    DeprecatedString resolve_object_path(StringView object_name) const;
+    ByteString resolve_object_path(StringView object_name) const;
 
     int process_pid() const;
     u8 process_termination_signal() const;
-    DeprecatedString process_executable_path() const;
-    Vector<DeprecatedString> process_arguments() const;
-    Vector<DeprecatedString> process_environment() const;
-    HashMap<DeprecatedString, DeprecatedString> metadata() const;
+    ByteString process_executable_path() const;
+    Vector<ByteString> process_arguments() const;
+    Vector<ByteString> process_environment() const;
+    HashMap<ByteString, ByteString> metadata() const;
 
 private:
     explicit Reader(ReadonlyBytes);
diff --git a/Userland/Libraries/LibCpp/AST.cpp b/Userland/Libraries/LibCpp/AST.cpp
index 8370b947967..14a7e0f1ea7 100644
--- a/Userland/Libraries/LibCpp/AST.cpp
+++ b/Userland/Libraries/LibCpp/AST.cpp
@@ -32,10 +32,10 @@ void FunctionDeclaration::dump(FILE* output, size_t indent) const
 {
     ASTNode::dump(output, indent);
 
-    DeprecatedString qualifiers_string;
+    ByteString qualifiers_string;
     if (!m_qualifiers.is_empty()) {
         print_indent(output, indent + 1);
-        outln(output, "[{}]", DeprecatedString::join(' ', m_qualifiers));
+        outln(output, "[{}]", ByteString::join(' ', m_qualifiers));
     }
 
     m_return_type->dump(output, indent + 1);
@@ -72,51 +72,51 @@ void Type::dump(FILE* output, size_t indent) const
 {
     ASTNode::dump(output, indent);
     print_indent(output, indent + 1);
-    outln(output, "{}", to_deprecated_string());
+    outln(output, "{}", to_byte_string());
 }
 
-DeprecatedString NamedType::to_deprecated_string() const
+ByteString NamedType::to_byte_string() const
 {
-    DeprecatedString qualifiers_string;
+    ByteString qualifiers_string;
     if (!qualifiers().is_empty())
-        qualifiers_string = DeprecatedString::formatted("[{}] ", DeprecatedString::join(' ', qualifiers()));
+        qualifiers_string = ByteString::formatted("[{}] ", ByteString::join(' ', qualifiers()));
 
-    DeprecatedString name;
+    ByteString name;
     if (is_auto())
         name = "auto";
     else
         name = m_name.is_null() ? ""sv : m_name->full_name();
 
-    return DeprecatedString::formatted("{}{}", qualifiers_string, name);
+    return ByteString::formatted("{}{}", qualifiers_string, name);
 }
 
-DeprecatedString Pointer::to_deprecated_string() const
+ByteString Pointer::to_byte_string() const
 {
     if (!m_pointee)
         return {};
     StringBuilder builder;
-    builder.append(m_pointee->to_deprecated_string());
+    builder.append(m_pointee->to_byte_string());
     builder.append('*');
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Reference::to_deprecated_string() const
+ByteString Reference::to_byte_string() const
 {
     if (!m_referenced_type)
         return {};
     StringBuilder builder;
-    builder.append(m_referenced_type->to_deprecated_string());
+    builder.append(m_referenced_type->to_byte_string());
     if (m_kind == Kind::Lvalue)
         builder.append('&');
     else
         builder.append("&&"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString FunctionType::to_deprecated_string() const
+ByteString FunctionType::to_byte_string() const
 {
     StringBuilder builder;
-    builder.append(m_return_type->to_deprecated_string());
+    builder.append(m_return_type->to_byte_string());
     builder.append('(');
     bool first = true;
     for (auto& parameter : m_parameters) {
@@ -125,14 +125,14 @@ DeprecatedString FunctionType::to_deprecated_string() const
         else
             builder.append(", "sv);
         if (parameter->type())
-            builder.append(parameter->type()->to_deprecated_string());
+            builder.append(parameter->type()->to_byte_string());
         if (parameter->name() && !parameter->full_name().is_empty()) {
             builder.append(' ');
             builder.append(parameter->full_name());
         }
     }
     builder.append(')');
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 void Parameter::dump(FILE* output, size_t indent) const
@@ -552,7 +552,7 @@ StringView Name::full_name() const
             builder.appendff("{}::", scope->name());
         }
     }
-    m_full_name = DeprecatedString::formatted("{}{}", builder.to_deprecated_string(), m_name.is_null() ? ""sv : m_name->name());
+    m_full_name = ByteString::formatted("{}{}", builder.to_byte_string(), m_name.is_null() ? ""sv : m_name->name());
     return *m_full_name;
 }
 
@@ -565,10 +565,10 @@ StringView TemplatizedName::full_name() const
     name.append(Name::full_name());
     name.append('<');
     for (auto& type : m_template_arguments) {
-        name.append(type->to_deprecated_string());
+        name.append(type->to_byte_string());
     }
     name.append('>');
-    m_full_name = name.to_deprecated_string();
+    m_full_name = name.to_byte_string();
     return *m_full_name;
 }
 
@@ -587,7 +587,7 @@ void SizedName::dump(FILE* output, size_t indent) const
     if (dimension_info.is_empty()) {
         dimension_info.append("[]"sv);
     }
-    outln(output, "{}", dimension_info.to_deprecated_string());
+    outln(output, "{}", dimension_info.to_byte_string());
 }
 
 void CppCastExpression::dump(FILE* output, size_t indent) const
@@ -670,7 +670,7 @@ StringView Declaration::full_name() const
         if (m_name)
             m_full_name = m_name->full_name();
         else
-            m_full_name = DeprecatedString::empty();
+            m_full_name = ByteString::empty();
     }
 
     return *m_full_name;
diff --git a/Userland/Libraries/LibCpp/AST.h b/Userland/Libraries/LibCpp/AST.h
index d08e42975ee..9b354b353c8 100644
--- a/Userland/Libraries/LibCpp/AST.h
+++ b/Userland/Libraries/LibCpp/AST.h
@@ -6,8 +6,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/DeprecatedFlyString.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Optional.h>
 #include <AK/RefCounted.h>
 #include <AK/StringView.h>
@@ -65,7 +65,7 @@ public:
     virtual bool is_dummy_node() const { return false; }
 
 protected:
-    ASTNode(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    ASTNode(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : m_parent(parent)
         , m_start(start)
         , m_end(end)
@@ -88,7 +88,7 @@ public:
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
     virtual Vector<NonnullRefPtr<Declaration const>> declarations() const override { return m_declarations; }
 
-    TranslationUnit(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    TranslationUnit(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : ASTNode(parent, start, end, filename)
     {
     }
@@ -107,7 +107,7 @@ public:
     virtual Vector<NonnullRefPtr<Declaration const>> declarations() const override;
 
 protected:
-    Statement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Statement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : ASTNode(parent, start, end, filename)
     {
     }
@@ -131,13 +131,13 @@ public:
     void set_name(RefPtr<Name const> name) { m_name = move(name); }
 
 protected:
-    Declaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Declaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Statement(parent, start, end, filename)
     {
     }
 
     RefPtr<Name const> m_name;
-    mutable Optional<DeprecatedString> m_full_name;
+    mutable Optional<ByteString> m_full_name;
 };
 
 class InvalidDeclaration : public Declaration {
@@ -145,7 +145,7 @@ class InvalidDeclaration : public Declaration {
 public:
     virtual ~InvalidDeclaration() override = default;
     virtual StringView class_name() const override { return "InvalidDeclaration"sv; }
-    InvalidDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    InvalidDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Declaration(parent, start, end, filename)
     {
     }
@@ -161,7 +161,7 @@ public:
     virtual bool is_destructor() const { return false; }
     RefPtr<FunctionDefinition const> definition() { return m_definition; }
 
-    FunctionDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    FunctionDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Declaration(parent, start, end, filename)
     {
     }
@@ -192,7 +192,7 @@ public:
     Type const* type() const { return m_type.ptr(); }
 
 protected:
-    VariableOrParameterDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    VariableOrParameterDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Declaration(parent, start, end, filename)
     {
     }
@@ -207,7 +207,7 @@ public:
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
     virtual bool is_parameter() const override { return true; }
 
-    Parameter(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename, RefPtr<Name const> name)
+    Parameter(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename, RefPtr<Name const> name)
         : VariableOrParameterDeclaration(parent, start, end, filename)
     {
         m_name = name;
@@ -227,7 +227,7 @@ public:
     virtual bool is_type() const override { return true; }
     virtual bool is_templatized() const { return false; }
     virtual bool is_named_type() const { return false; }
-    virtual DeprecatedString to_deprecated_string() const = 0;
+    virtual ByteString to_byte_string() const = 0;
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
     bool is_auto() const { return m_is_auto; }
@@ -236,7 +236,7 @@ public:
     void set_qualifiers(Vector<StringView>&& qualifiers) { m_qualifiers = move(qualifiers); }
 
 protected:
-    Type(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Type(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : ASTNode(parent, start, end, filename)
     {
     }
@@ -250,10 +250,10 @@ class NamedType : public Type {
 public:
     virtual ~NamedType() override = default;
     virtual StringView class_name() const override { return "NamedType"sv; }
-    virtual DeprecatedString to_deprecated_string() const override;
+    virtual ByteString to_byte_string() const override;
     virtual bool is_named_type() const override { return true; }
 
-    NamedType(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    NamedType(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Type(parent, start, end, filename)
     {
     }
@@ -270,9 +270,9 @@ public:
     virtual ~Pointer() override = default;
     virtual StringView class_name() const override { return "Pointer"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
-    virtual DeprecatedString to_deprecated_string() const override;
+    virtual ByteString to_byte_string() const override;
 
-    Pointer(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Pointer(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Type(parent, start, end, filename)
     {
     }
@@ -289,14 +289,14 @@ public:
     virtual ~Reference() override = default;
     virtual StringView class_name() const override { return "Reference"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
-    virtual DeprecatedString to_deprecated_string() const override;
+    virtual ByteString to_byte_string() const override;
 
     enum class Kind {
         Lvalue,
         Rvalue,
     };
 
-    Reference(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename, Kind kind)
+    Reference(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename, Kind kind)
         : Type(parent, start, end, filename)
         , m_kind(kind)
     {
@@ -316,9 +316,9 @@ public:
     virtual ~FunctionType() override = default;
     virtual StringView class_name() const override { return "FunctionType"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
-    virtual DeprecatedString to_deprecated_string() const override;
+    virtual ByteString to_byte_string() const override;
 
-    FunctionType(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    FunctionType(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Type(parent, start, end, filename)
     {
     }
@@ -337,7 +337,7 @@ public:
     virtual StringView class_name() const override { return "FunctionDefinition"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
-    FunctionDefinition(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    FunctionDefinition(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : ASTNode(parent, start, end, filename)
     {
     }
@@ -354,7 +354,7 @@ class InvalidStatement : public Statement {
 public:
     virtual ~InvalidStatement() override = default;
     virtual StringView class_name() const override { return "InvalidStatement"sv; }
-    InvalidStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    InvalidStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Statement(parent, start, end, filename)
     {
     }
@@ -366,7 +366,7 @@ public:
     virtual StringView class_name() const override { return "Expression"sv; }
 
 protected:
-    Expression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Expression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Statement(parent, start, end, filename)
     {
     }
@@ -376,7 +376,7 @@ class InvalidExpression : public Expression {
 public:
     virtual ~InvalidExpression() override = default;
     virtual StringView class_name() const override { return "InvalidExpression"sv; }
-    InvalidExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    InvalidExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -388,7 +388,7 @@ public:
     virtual StringView class_name() const override { return "VariableDeclaration"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
-    VariableDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    VariableDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : VariableOrParameterDeclaration(parent, start, end, filename)
     {
     }
@@ -408,12 +408,12 @@ public:
     virtual StringView class_name() const override { return "Identifier"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
-    Identifier(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename, StringView name)
+    Identifier(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename, StringView name)
         : Expression(parent, start, end, filename)
         , m_name(name)
     {
     }
-    Identifier(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Identifier(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Identifier(parent, start, end, filename, {})
     {
     }
@@ -436,7 +436,7 @@ public:
     virtual bool is_templatized() const { return false; }
     virtual bool is_sized() const { return false; }
 
-    Name(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Name(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -451,7 +451,7 @@ public:
 private:
     RefPtr<Identifier const> m_name;
     Vector<NonnullRefPtr<Identifier const>> m_scope;
-    mutable Optional<DeprecatedString> m_full_name;
+    mutable Optional<ByteString> m_full_name;
 };
 
 class SizedName : public Name {
@@ -461,7 +461,7 @@ public:
     virtual bool is_sized() const override { return true; }
     void dump(FILE* output, size_t indent) const override;
 
-    SizedName(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    SizedName(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Name(parent, start, end, filename)
     {
     }
@@ -470,7 +470,7 @@ public:
 
 private:
     Vector<StringView> m_dimensions;
-    mutable Optional<DeprecatedString> m_full_name;
+    mutable Optional<ByteString> m_full_name;
 };
 
 class TemplatizedName : public Name {
@@ -480,7 +480,7 @@ public:
     virtual bool is_templatized() const override { return true; }
     virtual StringView full_name() const override;
 
-    TemplatizedName(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    TemplatizedName(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Name(parent, start, end, filename)
     {
     }
@@ -489,7 +489,7 @@ public:
 
 private:
     Vector<NonnullRefPtr<Type const>> m_template_arguments;
-    mutable Optional<DeprecatedString> m_full_name;
+    mutable Optional<ByteString> m_full_name;
 };
 
 class NumericLiteral : public Expression {
@@ -498,7 +498,7 @@ public:
     virtual StringView class_name() const override { return "NumericLiteral"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
-    NumericLiteral(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename, StringView value)
+    NumericLiteral(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename, StringView value)
         : Expression(parent, start, end, filename)
         , m_value(value)
     {
@@ -516,7 +516,7 @@ public:
     virtual StringView class_name() const override { return "NullPointerLiteral"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
-    NullPointerLiteral(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    NullPointerLiteral(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -528,7 +528,7 @@ public:
     virtual StringView class_name() const override { return "BooleanLiteral"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
-    BooleanLiteral(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename, bool value)
+    BooleanLiteral(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename, bool value)
         : Expression(parent, start, end, filename)
         , m_value(value)
     {
@@ -562,7 +562,7 @@ enum class BinaryOp {
 
 class BinaryExpression : public Expression {
 public:
-    BinaryExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    BinaryExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -592,7 +592,7 @@ enum class AssignmentOp {
 
 class AssignmentExpression : public Expression {
 public:
-    AssignmentExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    AssignmentExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -616,7 +616,7 @@ private:
 
 class FunctionCall : public Expression {
 public:
-    FunctionCall(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    FunctionCall(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -639,7 +639,7 @@ private:
 
 class StringLiteral final : public Expression {
 public:
-    StringLiteral(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    StringLiteral(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -648,11 +648,11 @@ public:
     virtual StringView class_name() const override { return "StringLiteral"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
-    DeprecatedString const& value() const { return m_value; }
-    void set_value(DeprecatedString value) { m_value = move(value); }
+    ByteString const& value() const { return m_value; }
+    void set_value(ByteString value) { m_value = move(value); }
 
 private:
-    DeprecatedString m_value;
+    ByteString m_value;
 };
 
 class ReturnStatement : public Statement {
@@ -660,7 +660,7 @@ public:
     virtual ~ReturnStatement() override = default;
     virtual StringView class_name() const override { return "ReturnStatement"sv; }
 
-    ReturnStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    ReturnStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Statement(parent, start, end, filename)
     {
     }
@@ -680,7 +680,7 @@ public:
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
     virtual bool is_enum() const override { return true; }
 
-    EnumDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    EnumDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Declaration(parent, start, end, filename)
     {
     }
@@ -717,7 +717,7 @@ public:
         Class
     };
 
-    StructOrClassDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename, StructOrClassDeclaration::Type type)
+    StructOrClassDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename, StructOrClassDeclaration::Type type)
         : Declaration(parent, start, end, filename)
         , m_type(type)
     {
@@ -747,7 +747,7 @@ enum class UnaryOp {
 
 class UnaryExpression : public Expression {
 public:
-    UnaryExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    UnaryExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -766,7 +766,7 @@ private:
 
 class MemberExpression : public Expression {
 public:
-    MemberExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    MemberExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -788,7 +788,7 @@ private:
 
 class ForStatement : public Statement {
 public:
-    ForStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    ForStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Statement(parent, start, end, filename)
     {
     }
@@ -814,7 +814,7 @@ private:
 
 class BlockStatement final : public Statement {
 public:
-    BlockStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    BlockStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Statement(parent, start, end, filename)
     {
     }
@@ -835,7 +835,7 @@ private:
 
 class Comment final : public Statement {
 public:
-    Comment(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Comment(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Statement(parent, start, end, filename)
     {
     }
@@ -846,7 +846,7 @@ public:
 
 class IfStatement : public Statement {
 public:
-    IfStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    IfStatement(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Statement(parent, start, end, filename)
     {
     }
@@ -877,7 +877,7 @@ public:
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
     virtual bool is_namespace() const override { return true; }
 
-    NamespaceDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    NamespaceDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Declaration(parent, start, end, filename)
     {
     }
@@ -891,7 +891,7 @@ private:
 
 class CppCastExpression : public Expression {
 public:
-    CppCastExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    CppCastExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -912,7 +912,7 @@ private:
 
 class CStyleCastExpression : public Expression {
 public:
-    CStyleCastExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    CStyleCastExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -931,7 +931,7 @@ private:
 
 class SizeofExpression : public Expression {
 public:
-    SizeofExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    SizeofExpression(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -948,7 +948,7 @@ private:
 
 class BracedInitList : public Expression {
 public:
-    BracedInitList(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    BracedInitList(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Expression(parent, start, end, filename)
     {
     }
@@ -965,7 +965,7 @@ private:
 
 class DummyAstNode : public ASTNode {
 public:
-    DummyAstNode(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    DummyAstNode(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : ASTNode(parent, start, end, filename)
     {
     }
@@ -981,7 +981,7 @@ public:
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
     virtual bool is_constructor() const override { return true; }
 
-    Constructor(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Constructor(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : FunctionDeclaration(parent, start, end, filename)
     {
     }
@@ -994,7 +994,7 @@ public:
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
     virtual bool is_destructor() const override { return true; }
 
-    Destructor(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    Destructor(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : FunctionDeclaration(parent, start, end, filename)
     {
     }
@@ -1006,7 +1006,7 @@ public:
     virtual StringView class_name() const override { return "UsingNamespaceDeclaration"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
-    UsingNamespaceDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    UsingNamespaceDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Declaration(parent, start, end, filename)
     {
     }
@@ -1018,7 +1018,7 @@ public:
     virtual StringView class_name() const override { return "TypedefDeclaration"sv; }
     virtual void dump(FILE* = stdout, size_t indent = 0) const override;
 
-    TypedefDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, DeprecatedString const& filename)
+    TypedefDeclaration(ASTNode const* parent, Optional<Position> start, Optional<Position> end, ByteString const& filename)
         : Declaration(parent, start, end, filename)
     {
     }
diff --git a/Userland/Libraries/LibCpp/Lexer.cpp b/Userland/Libraries/LibCpp/Lexer.cpp
index d10083fa756..e7ab750ca69 100644
--- a/Userland/Libraries/LibCpp/Lexer.cpp
+++ b/Userland/Libraries/LibCpp/Lexer.cpp
@@ -5,8 +5,8 @@
  */
 
 #include "Lexer.h"
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Function.h>
 #include <AK/HashTable.h>
 #include <AK/StdLibExtras.h>
@@ -203,7 +203,7 @@ constexpr StringView s_known_types[] = {
 
 static bool is_keyword(StringView string)
 {
-    static HashTable<DeprecatedString> keywords(array_size(s_known_keywords));
+    static HashTable<ByteString> keywords(array_size(s_known_keywords));
     if (keywords.is_empty()) {
         keywords.set_from(s_known_keywords);
     }
@@ -212,7 +212,7 @@ static bool is_keyword(StringView string)
 
 static bool is_known_type(StringView string)
 {
-    static HashTable<DeprecatedString> types(array_size(s_known_types));
+    static HashTable<ByteString> types(array_size(s_known_types));
     if (types.is_empty()) {
         types.set_from(s_known_types);
     }
diff --git a/Userland/Libraries/LibCpp/Parser.cpp b/Userland/Libraries/LibCpp/Parser.cpp
index d39c30a0b2c..2ecb7ff5bc6 100644
--- a/Userland/Libraries/LibCpp/Parser.cpp
+++ b/Userland/Libraries/LibCpp/Parser.cpp
@@ -11,18 +11,18 @@
 #include <AK/ScopeLogger.h>
 #include <LibCpp/Lexer.h>
 
-#define LOG_SCOPE() ScopeLogger<CPP_DEBUG> logger(DeprecatedString::formatted("'{}' - {} ({})", peek().text(), peek().type_as_deprecated_string(), m_state.token_index))
+#define LOG_SCOPE() ScopeLogger<CPP_DEBUG> logger(ByteString::formatted("'{}' - {} ({})", peek().text(), peek().type_as_byte_string(), m_state.token_index))
 
 namespace Cpp {
 
-Parser::Parser(Vector<Token> tokens, DeprecatedString const& filename)
+Parser::Parser(Vector<Token> tokens, ByteString const& filename)
     : m_filename(filename)
     , m_tokens(move(tokens))
 {
     if constexpr (CPP_DEBUG) {
         dbgln("Tokens:");
         for (size_t i = 0; i < m_tokens.size(); ++i) {
-            dbgln("{}- {}", i, m_tokens[i].to_deprecated_string());
+            dbgln("{}- {}", i, m_tokens[i].to_byte_string());
         }
     }
 }
@@ -598,7 +598,7 @@ NonnullRefPtr<Expression const> Parser::parse_secondary_expression(ASTNode const
         return func;
     }
     default: {
-        error(DeprecatedString::formatted("unexpected operator for expression. operator: {}", peek().to_deprecated_string()));
+        error(ByteString::formatted("unexpected operator for expression. operator: {}", peek().to_byte_string()));
         auto token = consume();
         return create_ast_node<InvalidExpression>(parent, token.start(), token.end());
     }
@@ -845,7 +845,7 @@ Token Parser::consume(Token::Type type)
 {
     auto token = consume();
     if (token.type() != type)
-        error(DeprecatedString::formatted("expected {} at {}:{}, found: {}", Token::type_to_string(type), token.start().line, token.start().column, Token::type_to_string(token.type())));
+        error(ByteString::formatted("expected {} at {}:{}, found: {}", Token::type_to_string(type), token.start().line, token.start().column, Token::type_to_string(token.type())));
     return token;
 }
 
@@ -894,18 +894,18 @@ StringView Parser::text_of_token(Cpp::Token const& token) const
     return token.text();
 }
 
-DeprecatedString Parser::text_of_node(ASTNode const& node) const
+ByteString Parser::text_of_node(ASTNode const& node) const
 {
     return text_in_range(node.start(), node.end());
 }
 
-DeprecatedString Parser::text_in_range(Position start, Position end) const
+ByteString Parser::text_in_range(Position start, Position end) const
 {
     StringBuilder builder;
     for (auto token : tokens_in_range(start, end)) {
         builder.append(token.text());
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 Vector<Token> Parser::tokens_in_range(Position start, Position end) const
@@ -931,11 +931,11 @@ void Parser::error(StringView message)
 
     if (message.is_null() || message.is_empty())
         message = "<empty>"sv;
-    DeprecatedString formatted_message;
+    ByteString formatted_message;
     if (m_state.token_index >= m_tokens.size()) {
-        formatted_message = DeprecatedString::formatted("C++ Parsed error on EOF.{}", message);
+        formatted_message = ByteString::formatted("C++ Parsed error on EOF.{}", message);
     } else {
-        formatted_message = DeprecatedString::formatted("C++ Parser error: {}. token: {} ({}:{})",
+        formatted_message = ByteString::formatted("C++ Parser error: {}. token: {} ({}:{})",
             message,
             m_state.token_index < m_tokens.size() ? text_of_token(m_tokens[m_state.token_index]) : "EOF"sv,
             m_tokens[m_state.token_index].start().line,
@@ -1033,7 +1033,7 @@ Optional<size_t> Parser::index_of_token_at(Position pos) const
 void Parser::print_tokens() const
 {
     for (auto& token : m_tokens) {
-        outln("{}", token.to_deprecated_string());
+        outln("{}", token.to_byte_string());
     }
 }
 
@@ -1131,21 +1131,21 @@ NonnullRefPtr<EnumDeclaration const> Parser::parse_enum_declaration(ASTNode cons
     return enum_decl;
 }
 
-Token Parser::consume_keyword(DeprecatedString const& keyword)
+Token Parser::consume_keyword(ByteString const& keyword)
 {
     auto token = consume();
     if (token.type() != Token::Type::Keyword) {
-        error(DeprecatedString::formatted("unexpected token: {}, expected Keyword", token.to_deprecated_string()));
+        error(ByteString::formatted("unexpected token: {}, expected Keyword", token.to_byte_string()));
         return token;
     }
     if (text_of_token(token) != keyword) {
-        error(DeprecatedString::formatted("unexpected keyword: {}, expected {}", text_of_token(token), keyword));
+        error(ByteString::formatted("unexpected keyword: {}, expected {}", text_of_token(token), keyword));
         return token;
     }
     return token;
 }
 
-bool Parser::match_keyword(DeprecatedString const& keyword)
+bool Parser::match_keyword(ByteString const& keyword)
 {
     auto token = peek();
     if (token.type() != Token::Type::Keyword) {
@@ -1257,7 +1257,7 @@ NonnullRefPtr<Type const> Parser::parse_type(ASTNode const& parent)
 
     if (!match_name()) {
         named_type->set_end(position());
-        error(DeprecatedString::formatted("expected name instead of: {}", peek().text()));
+        error(ByteString::formatted("expected name instead of: {}", peek().text()));
         return named_type;
     }
     named_type->set_name(parse_name(*named_type));
diff --git a/Userland/Libraries/LibCpp/Parser.h b/Userland/Libraries/LibCpp/Parser.h
index e43f238d88d..1f0d6d65343 100644
--- a/Userland/Libraries/LibCpp/Parser.h
+++ b/Userland/Libraries/LibCpp/Parser.h
@@ -19,7 +19,7 @@ class Parser final {
     AK_MAKE_NONCOPYABLE(Parser);
 
 public:
-    explicit Parser(Vector<Token> tokens, DeprecatedString const& filename);
+    explicit Parser(Vector<Token> tokens, ByteString const& filename);
     ~Parser() = default;
 
     NonnullRefPtr<TranslationUnit> parse();
@@ -30,11 +30,11 @@ public:
     Optional<Token> token_at(Position) const;
     Optional<size_t> index_of_token_at(Position) const;
     RefPtr<TranslationUnit const> root_node() const { return m_root_node; }
-    DeprecatedString text_of_node(ASTNode const&) const;
+    ByteString text_of_node(ASTNode const&) const;
     StringView text_of_token(Cpp::Token const& token) const;
     void print_tokens() const;
     Vector<Token> const& tokens() const { return m_tokens; }
-    Vector<DeprecatedString> const& errors() const { return m_errors; }
+    Vector<ByteString> const& errors() const { return m_errors; }
 
     Vector<CodeComprehension::TodoEntry> get_todo_entries() const;
 
@@ -69,7 +69,7 @@ private:
     bool match_literal();
     bool match_unary_expression();
     bool match_boolean_literal();
-    bool match_keyword(DeprecatedString const&);
+    bool match_keyword(ByteString const&);
     bool match_block_statement();
     bool match_namespace_declaration();
     bool match_template_arguments();
@@ -132,12 +132,12 @@ private:
     bool match(Token::Type);
     Token consume(Token::Type);
     Token consume();
-    Token consume_keyword(DeprecatedString const&);
+    Token consume_keyword(ByteString const&);
     Token peek(size_t offset = 0) const;
     Optional<Token> peek(Token::Type) const;
     Position position() const;
     Position previous_token_end() const;
-    DeprecatedString text_in_range(Position start, Position end) const;
+    ByteString text_in_range(Position start, Position end) const;
 
     void save_state();
     void load_state();
@@ -192,12 +192,12 @@ private:
     };
     void parse_constructor_or_destructor_impl(FunctionDeclaration&, CtorOrDtor);
 
-    DeprecatedString m_filename;
+    ByteString m_filename;
     Vector<Token> m_tokens;
     State m_state;
     Vector<State> m_saved_states;
     RefPtr<TranslationUnit> m_root_node;
-    Vector<DeprecatedString> m_errors;
+    Vector<ByteString> m_errors;
     Vector<NonnullRefPtr<ASTNode>> m_nodes;
 };
 
diff --git a/Userland/Libraries/LibCpp/Preprocessor.cpp b/Userland/Libraries/LibCpp/Preprocessor.cpp
index 8a0832c7637..2de36a47b48 100644
--- a/Userland/Libraries/LibCpp/Preprocessor.cpp
+++ b/Userland/Libraries/LibCpp/Preprocessor.cpp
@@ -12,7 +12,7 @@
 #include <ctype.h>
 
 namespace Cpp {
-Preprocessor::Preprocessor(DeprecatedString const& filename, StringView program)
+Preprocessor::Preprocessor(ByteString const& filename, StringView program)
     : m_filename(filename)
     , m_program(program)
 {
@@ -369,7 +369,7 @@ Optional<Preprocessor::Definition> Preprocessor::create_definition(StringView li
     return definition;
 }
 
-DeprecatedString Preprocessor::remove_escaped_newlines(StringView value)
+ByteString Preprocessor::remove_escaped_newlines(StringView value)
 {
     static constexpr auto escaped_newline = "\\\n"sv;
     AK::StringBuilder processed_value;
@@ -378,10 +378,10 @@ DeprecatedString Preprocessor::remove_escaped_newlines(StringView value)
         processed_value.append(lexer.consume_until(escaped_newline));
         lexer.ignore(escaped_newline.length());
     }
-    return processed_value.to_deprecated_string();
+    return processed_value.to_byte_string();
 }
 
-DeprecatedString Preprocessor::evaluate_macro_call(MacroCall const& macro_call, Definition const& definition)
+ByteString Preprocessor::evaluate_macro_call(MacroCall const& macro_call, Definition const& definition)
 {
     if (macro_call.arguments.size() != definition.parameters.size()) {
         dbgln("mismatch in # of arguments for macro call: {}", macro_call.name.text());
@@ -408,7 +408,7 @@ DeprecatedString Preprocessor::evaluate_macro_call(MacroCall const& macro_call,
         }
     });
 
-    return processed_value.to_deprecated_string();
+    return processed_value.to_byte_string();
 }
 
 };
diff --git a/Userland/Libraries/LibCpp/Preprocessor.h b/Userland/Libraries/LibCpp/Preprocessor.h
index eb98146a5a5..337c40d7090 100644
--- a/Userland/Libraries/LibCpp/Preprocessor.h
+++ b/Userland/Libraries/LibCpp/Preprocessor.h
@@ -6,8 +6,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/DeprecatedFlyString.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/Optional.h>
@@ -20,24 +20,24 @@ namespace Cpp {
 class Preprocessor {
 
 public:
-    explicit Preprocessor(DeprecatedString const& filename, StringView program);
+    explicit Preprocessor(ByteString const& filename, StringView program);
     Vector<Token> process_and_lex();
     Vector<StringView> included_paths() const { return m_included_paths; }
 
     struct Definition {
-        DeprecatedString key;
-        Vector<DeprecatedString> parameters;
-        DeprecatedString value;
+        ByteString key;
+        Vector<ByteString> parameters;
+        ByteString value;
         DeprecatedFlyString filename;
         size_t line { 0 };
         size_t column { 0 };
     };
-    using Definitions = HashMap<DeprecatedString, Definition>;
+    using Definitions = HashMap<ByteString, Definition>;
 
     struct Substitution {
         Vector<Token> original_tokens;
         Definition defined_value;
-        DeprecatedString processed_value;
+        ByteString processed_value;
     };
 
     Definitions const& definitions() const { return m_definitions; }
@@ -55,7 +55,7 @@ private:
     void handle_preprocessor_statement(StringView);
     void handle_include_statement(StringView);
     void handle_preprocessor_keyword(StringView keyword, GenericLexer& line_lexer);
-    DeprecatedString remove_escaped_newlines(StringView value);
+    ByteString remove_escaped_newlines(StringView value);
 
     size_t do_substitution(Vector<Token> const& tokens, size_t token_index, Definition const&);
     Optional<Definition> create_definition(StringView line);
@@ -69,10 +69,10 @@ private:
         size_t end_token_index { 0 };
     };
     Optional<MacroCall> parse_macro_call(Vector<Token> const& tokens, size_t token_index);
-    DeprecatedString evaluate_macro_call(MacroCall const&, Definition const&);
+    ByteString evaluate_macro_call(MacroCall const&, Definition const&);
 
-    DeprecatedString m_filename;
-    DeprecatedString m_program;
+    ByteString m_filename;
+    ByteString m_program;
 
     Vector<Token> m_unprocessed_tokens;
     Vector<Token> m_processed_tokens;
diff --git a/Userland/Libraries/LibCpp/SemanticSyntaxHighlighter.cpp b/Userland/Libraries/LibCpp/SemanticSyntaxHighlighter.cpp
index 2f37178905b..cb2f941794d 100644
--- a/Userland/Libraries/LibCpp/SemanticSyntaxHighlighter.cpp
+++ b/Userland/Libraries/LibCpp/SemanticSyntaxHighlighter.cpp
@@ -45,13 +45,13 @@ void SemanticSyntaxHighlighter::rehighlight(Palette const& palette)
         StringBuilder previous_tokens_as_lines;
 
         for (auto& token : current_tokens)
-            current_tokens_as_lines.appendff("{}\n", token.type_as_deprecated_string());
+            current_tokens_as_lines.appendff("{}\n", token.type_as_byte_string());
 
         for (Cpp::Token const& token : m_saved_tokens)
-            previous_tokens_as_lines.appendff("{}\n", token.type_as_deprecated_string());
+            previous_tokens_as_lines.appendff("{}\n", token.type_as_byte_string());
 
-        auto previous = previous_tokens_as_lines.to_deprecated_string();
-        auto current = current_tokens_as_lines.to_deprecated_string();
+        auto previous = previous_tokens_as_lines.to_byte_string();
+        auto current = current_tokens_as_lines.to_byte_string();
 
         // FIXME: Computing the diff on the entire document's tokens is quite inefficient.
         //        An improvement over this could be only including the tokens that are in edited text ranges in the diff.
diff --git a/Userland/Libraries/LibCpp/SemanticSyntaxHighlighter.h b/Userland/Libraries/LibCpp/SemanticSyntaxHighlighter.h
index eb8787e67d2..b3b0913803b 100644
--- a/Userland/Libraries/LibCpp/SemanticSyntaxHighlighter.h
+++ b/Userland/Libraries/LibCpp/SemanticSyntaxHighlighter.h
@@ -43,7 +43,7 @@ private:
 
     Cpp::SyntaxHighlighter m_simple_syntax_highlighter;
     Vector<CodeComprehension::TokenInfo> m_tokens_info;
-    DeprecatedString m_saved_tokens_text;
+    ByteString m_saved_tokens_text;
     Vector<Token> m_saved_tokens;
     Threading::Mutex m_lock;
 };
diff --git a/Userland/Libraries/LibCpp/SyntaxHighlighter.cpp b/Userland/Libraries/LibCpp/SyntaxHighlighter.cpp
index dcb1e251167..da9bc8bc82e 100644
--- a/Userland/Libraries/LibCpp/SyntaxHighlighter.cpp
+++ b/Userland/Libraries/LibCpp/SyntaxHighlighter.cpp
@@ -65,7 +65,7 @@ void SyntaxHighlighter::rehighlight(Palette const& palette)
     Vector<GUI::TextDocumentSpan> spans;
     lexer.lex_iterable([&](auto token) {
         // FIXME: The +1 for the token end column is a quick hack due to not wanting to modify the lexer (which is also used by the parser). Maybe there's a better way to do this.
-        dbgln_if(SYNTAX_HIGHLIGHTING_DEBUG, "{} @ {}:{} - {}:{}", token.type_as_deprecated_string(), token.start().line, token.start().column, token.end().line, token.end().column + 1);
+        dbgln_if(SYNTAX_HIGHLIGHTING_DEBUG, "{} @ {}:{} - {}:{}", token.type_as_byte_string(), token.start().line, token.start().column, token.end().line, token.end().column + 1);
         GUI::TextDocumentSpan span;
         span.range.set_start({ token.start().line, token.start().column });
         span.range.set_end({ token.end().line, token.end().column + 1 });
diff --git a/Userland/Libraries/LibCpp/Token.cpp b/Userland/Libraries/LibCpp/Token.cpp
index 60b5a1fb8af..b82bcd6d9fb 100644
--- a/Userland/Libraries/LibCpp/Token.cpp
+++ b/Userland/Libraries/LibCpp/Token.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "Token.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 
 namespace Cpp {
 
@@ -26,12 +26,12 @@ bool Position::operator<=(Position const& other) const
     return !(*this > other);
 }
 
-DeprecatedString Token::to_deprecated_string() const
+ByteString Token::to_byte_string() const
 {
-    return DeprecatedString::formatted("{}  {}:{}-{}:{} ({})", type_to_string(m_type), start().line, start().column, end().line, end().column, text());
+    return ByteString::formatted("{}  {}:{}-{}:{} ({})", type_to_string(m_type), start().line, start().column, end().line, end().column, text());
 }
 
-DeprecatedString Token::type_as_deprecated_string() const
+ByteString Token::type_as_byte_string() const
 {
     return type_to_string(m_type);
 }
diff --git a/Userland/Libraries/LibCpp/Token.h b/Userland/Libraries/LibCpp/Token.h
index 7986aaa9c82..2448e7f06f7 100644
--- a/Userland/Libraries/LibCpp/Token.h
+++ b/Userland/Libraries/LibCpp/Token.h
@@ -116,8 +116,8 @@ struct Token {
         VERIFY_NOT_REACHED();
     }
 
-    DeprecatedString to_deprecated_string() const;
-    DeprecatedString type_as_deprecated_string() const;
+    ByteString to_byte_string() const;
+    ByteString type_as_byte_string() const;
 
     Position const& start() const { return m_start; }
     Position const& end() const { return m_end; }
diff --git a/Userland/Libraries/LibCrypt/crypt.cpp b/Userland/Libraries/LibCrypt/crypt.cpp
index fcb378353e6..7d6a4f09c9c 100644
--- a/Userland/Libraries/LibCrypt/crypt.cpp
+++ b/Userland/Libraries/LibCrypt/crypt.cpp
@@ -40,7 +40,7 @@ char* crypt_r(char const* key, char const* salt, struct crypt_data* data)
     size_t salt_len = min(strcspn(salt_value, "$"), crypt_salt_max);
     size_t header_len = salt_len + 3;
 
-    bool fits = DeprecatedString(salt, header_len).copy_characters_to_buffer(data->result, sizeof(data->result));
+    bool fits = ByteString(salt, header_len).copy_characters_to_buffer(data->result, sizeof(data->result));
     if (!fits) {
         errno = EINVAL;
         return nullptr;
diff --git a/Userland/Libraries/LibCrypto/ASN1/ASN1.cpp b/Userland/Libraries/LibCrypto/ASN1/ASN1.cpp
index 25c66441eb7..73a09e538f9 100644
--- a/Userland/Libraries/LibCrypto/ASN1/ASN1.cpp
+++ b/Userland/Libraries/LibCrypto/ASN1/ASN1.cpp
@@ -9,7 +9,7 @@
 
 namespace Crypto::ASN1 {
 
-DeprecatedString kind_name(Kind kind)
+ByteString kind_name(Kind kind)
 {
     switch (kind) {
     case Kind::Eol:
@@ -91,7 +91,7 @@ DeprecatedString kind_name(Kind kind)
     return "InvalidKind";
 }
 
-DeprecatedString class_name(Class class_)
+ByteString class_name(Class class_)
 {
     switch (class_) {
     case Class::Application:
@@ -107,7 +107,7 @@ DeprecatedString class_name(Class class_)
     return "InvalidClass";
 }
 
-DeprecatedString type_name(Type type)
+ByteString type_name(Type type)
 {
     switch (type) {
     case Type::Constructed:
diff --git a/Userland/Libraries/LibCrypto/ASN1/ASN1.h b/Userland/Libraries/LibCrypto/ASN1/ASN1.h
index 5553b7d81b7..4c4f0ac7322 100644
--- a/Userland/Libraries/LibCrypto/ASN1/ASN1.h
+++ b/Userland/Libraries/LibCrypto/ASN1/ASN1.h
@@ -71,9 +71,9 @@ struct Tag {
     Type type;
 };
 
-DeprecatedString kind_name(Kind);
-DeprecatedString class_name(Class);
-DeprecatedString type_name(Type);
+ByteString kind_name(Kind);
+ByteString class_name(Class);
+ByteString type_name(Type);
 
 Optional<Core::DateTime> parse_utc_time(StringView);
 Optional<Core::DateTime> parse_generalized_time(StringView);
diff --git a/Userland/Libraries/LibCrypto/Authentication/GHash.h b/Userland/Libraries/LibCrypto/Authentication/GHash.h
index 6b1f955ceb4..e61a09b76b6 100644
--- a/Userland/Libraries/LibCrypto/Authentication/GHash.h
+++ b/Userland/Libraries/LibCrypto/Authentication/GHash.h
@@ -12,7 +12,7 @@
 #include <LibCrypto/Hash/HashFunction.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::Authentication {
@@ -48,7 +48,7 @@ public:
     constexpr static size_t digest_size() { return TagType::Size; }
 
 #ifndef KERNEL
-    DeprecatedString class_name() const
+    ByteString class_name() const
     {
         return "GHash";
     }
diff --git a/Userland/Libraries/LibCrypto/Authentication/HMAC.h b/Userland/Libraries/LibCrypto/Authentication/HMAC.h
index 71b4e9732a2..29e353c6e8b 100644
--- a/Userland/Libraries/LibCrypto/Authentication/HMAC.h
+++ b/Userland/Libraries/LibCrypto/Authentication/HMAC.h
@@ -13,7 +13,7 @@
 #include <AK/Vector.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 constexpr static auto IPAD = 0x36;
@@ -73,12 +73,12 @@ public:
     }
 
 #ifndef KERNEL
-    DeprecatedString class_name() const
+    ByteString class_name() const
     {
         StringBuilder builder;
         builder.append("HMAC-"sv);
         builder.append(m_inner_hasher.class_name());
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 #endif
 
diff --git a/Userland/Libraries/LibCrypto/BigFraction/BigFraction.cpp b/Userland/Libraries/LibCrypto/BigFraction/BigFraction.cpp
index f7694db5a76..97c2382def3 100644
--- a/Userland/Libraries/LibCrypto/BigFraction/BigFraction.cpp
+++ b/Userland/Libraries/LibCrypto/BigFraction/BigFraction.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "BigFraction.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Math.h>
 #include <AK/StringBuilder.h>
 #include <LibCrypto/NumberTheory/ModularFunctions.h>
@@ -184,7 +184,7 @@ void BigFraction::reduce()
     m_denominator = denominator_divide.quotient;
 }
 
-DeprecatedString BigFraction::to_deprecated_string(unsigned rounding_threshold) const
+ByteString BigFraction::to_byte_string(unsigned rounding_threshold) const
 {
     StringBuilder builder;
     if (m_numerator.is_negative() && m_numerator != "0"_bigint)
@@ -239,7 +239,7 @@ DeprecatedString BigFraction::to_deprecated_string(unsigned rounding_threshold)
             builder.append(fractional_value);
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 BigFraction BigFraction::sqrt() const
diff --git a/Userland/Libraries/LibCrypto/BigFraction/BigFraction.h b/Userland/Libraries/LibCrypto/BigFraction/BigFraction.h
index 25a8352ad9d..682fe9431dc 100644
--- a/Userland/Libraries/LibCrypto/BigFraction/BigFraction.h
+++ b/Userland/Libraries/LibCrypto/BigFraction/BigFraction.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCrypto/BigInt/SignedBigInteger.h>
 
 namespace Crypto {
@@ -54,7 +54,7 @@ public:
     //      - m_denominator = 10000
     BigFraction rounded(unsigned rounding_threshold) const;
 
-    DeprecatedString to_deprecated_string(unsigned rounding_threshold) const;
+    ByteString to_byte_string(unsigned rounding_threshold) const;
     double to_double() const;
 
 private:
diff --git a/Userland/Libraries/LibCrypto/BigInt/SignedBigInteger.cpp b/Userland/Libraries/LibCrypto/BigInt/SignedBigInteger.cpp
index 76421ed7082..1aca97dfc35 100644
--- a/Userland/Libraries/LibCrypto/BigInt/SignedBigInteger.cpp
+++ b/Userland/Libraries/LibCrypto/BigInt/SignedBigInteger.cpp
@@ -64,9 +64,9 @@ ErrorOr<String> SignedBigInteger::to_base(u16 N) const
     return builder.to_string();
 }
 
-DeprecatedString SignedBigInteger::to_base_deprecated(u16 N) const
+ByteString SignedBigInteger::to_base_deprecated(u16 N) const
 {
-    return MUST(to_base(N)).to_deprecated_string();
+    return MUST(to_base(N)).to_byte_string();
 }
 
 u64 SignedBigInteger::to_u64() const
diff --git a/Userland/Libraries/LibCrypto/BigInt/SignedBigInteger.h b/Userland/Libraries/LibCrypto/BigInt/SignedBigInteger.h
index 83168baa973..f6100d8bc5d 100644
--- a/Userland/Libraries/LibCrypto/BigInt/SignedBigInteger.h
+++ b/Userland/Libraries/LibCrypto/BigInt/SignedBigInteger.h
@@ -65,7 +65,7 @@ public:
 
     [[nodiscard]] static SignedBigInteger from_base(u16 N, StringView str);
     [[nodiscard]] ErrorOr<String> to_base(u16 N) const;
-    [[nodiscard]] DeprecatedString to_base_deprecated(u16 N) const;
+    [[nodiscard]] ByteString to_base_deprecated(u16 N) const;
 
     [[nodiscard]] u64 to_u64() const;
     [[nodiscard]] double to_double(UnsignedBigInteger::RoundingMode rounding_mode = UnsignedBigInteger::RoundingMode::IEEERoundAndTiesToEvenMantissa) const;
diff --git a/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp b/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
index 7b35a7451e0..041e92eb0da 100644
--- a/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
+++ b/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
@@ -167,9 +167,9 @@ ErrorOr<String> UnsignedBigInteger::to_base(u16 N) const
     return TRY(builder.to_string()).reverse();
 }
 
-DeprecatedString UnsignedBigInteger::to_base_deprecated(u16 N) const
+ByteString UnsignedBigInteger::to_base_deprecated(u16 N) const
 {
-    return MUST(to_base(N)).to_deprecated_string();
+    return MUST(to_base(N)).to_byte_string();
 }
 
 u64 UnsignedBigInteger::to_u64() const
diff --git a/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h b/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
index 6fb7975b3c1..2df4652ec57 100644
--- a/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
+++ b/Userland/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
@@ -9,8 +9,8 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
+#include <AK/ByteString.h>
 #include <AK/Concepts.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Span.h>
 #include <AK/String.h>
 #include <AK/Types.h>
@@ -65,7 +65,7 @@ public:
 
     [[nodiscard]] static UnsignedBigInteger from_base(u16 N, StringView str);
     [[nodiscard]] ErrorOr<String> to_base(u16 N) const;
-    [[nodiscard]] DeprecatedString to_base_deprecated(u16 N) const;
+    [[nodiscard]] ByteString to_base_deprecated(u16 N) const;
 
     [[nodiscard]] u64 to_u64() const;
 
diff --git a/Userland/Libraries/LibCrypto/Cipher/AES.cpp b/Userland/Libraries/LibCrypto/Cipher/AES.cpp
index 3f5d8994538..1c63e5abb17 100644
--- a/Userland/Libraries/LibCrypto/Cipher/AES.cpp
+++ b/Userland/Libraries/LibCrypto/Cipher/AES.cpp
@@ -24,20 +24,20 @@ constexpr void swap_keys(u32* keys, size_t i, size_t j)
 }
 
 #ifndef KERNEL
-DeprecatedString AESCipherBlock::to_deprecated_string() const
+ByteString AESCipherBlock::to_byte_string() const
 {
     StringBuilder builder;
     for (auto value : m_data)
         builder.appendff("{:02x}", value);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString AESCipherKey::to_deprecated_string() const
+ByteString AESCipherKey::to_byte_string() const
 {
     StringBuilder builder;
     for (size_t i = 0; i < (rounds() + 1) * 4; ++i)
         builder.appendff("{:02x}", m_rd_keys[i]);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 #endif
 
diff --git a/Userland/Libraries/LibCrypto/Cipher/AES.h b/Userland/Libraries/LibCrypto/Cipher/AES.h
index 3221b53eea5..835188c17cc 100644
--- a/Userland/Libraries/LibCrypto/Cipher/AES.h
+++ b/Userland/Libraries/LibCrypto/Cipher/AES.h
@@ -14,7 +14,7 @@
 #include <LibCrypto/Cipher/Mode/GCM.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::Cipher {
@@ -48,7 +48,7 @@ public:
     }
 
 #ifndef KERNEL
-    DeprecatedString to_deprecated_string() const;
+    ByteString to_byte_string() const;
 #endif
 
 private:
@@ -64,7 +64,7 @@ struct AESCipherKey : public CipherKey {
     static bool is_valid_key_size(size_t bits) { return bits == 128 || bits == 192 || bits == 256; }
 
 #ifndef KERNEL
-    DeprecatedString to_deprecated_string() const;
+    ByteString to_byte_string() const;
 #endif
 
     u32 const* round_keys() const
@@ -120,7 +120,7 @@ public:
     virtual void decrypt_block(BlockType const& in, BlockType& out) override;
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         return "AES";
     }
diff --git a/Userland/Libraries/LibCrypto/Cipher/Cipher.h b/Userland/Libraries/LibCrypto/Cipher/Cipher.h
index 6a9dee84b8a..acfcbc0dd9b 100644
--- a/Userland/Libraries/LibCrypto/Cipher/Cipher.h
+++ b/Userland/Libraries/LibCrypto/Cipher/Cipher.h
@@ -112,7 +112,7 @@ public:
     virtual void decrypt_block(BlockType const& in, BlockType& out) = 0;
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const = 0;
+    virtual ByteString class_name() const = 0;
 #endif
 
 protected:
diff --git a/Userland/Libraries/LibCrypto/Cipher/Mode/CBC.h b/Userland/Libraries/LibCrypto/Cipher/Mode/CBC.h
index 69519d7f987..777121a4dba 100644
--- a/Userland/Libraries/LibCrypto/Cipher/Mode/CBC.h
+++ b/Userland/Libraries/LibCrypto/Cipher/Mode/CBC.h
@@ -11,7 +11,7 @@
 #include <LibCrypto/Cipher/Mode/Mode.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::Cipher {
@@ -29,12 +29,12 @@ public:
     }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         StringBuilder builder;
         builder.append(this->cipher().class_name());
         builder.append("_CBC"sv);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 #endif
 
diff --git a/Userland/Libraries/LibCrypto/Cipher/Mode/CTR.h b/Userland/Libraries/LibCrypto/Cipher/Mode/CTR.h
index 4c002f66a2f..7420d82ea25 100644
--- a/Userland/Libraries/LibCrypto/Cipher/Mode/CTR.h
+++ b/Userland/Libraries/LibCrypto/Cipher/Mode/CTR.h
@@ -11,7 +11,7 @@
 #include <LibCrypto/Cipher/Mode/Mode.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::Cipher {
@@ -104,12 +104,12 @@ public:
     }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         StringBuilder builder;
         builder.append(this->cipher().class_name());
         builder.append("_CTR"sv);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 #endif
 
diff --git a/Userland/Libraries/LibCrypto/Cipher/Mode/GCM.h b/Userland/Libraries/LibCrypto/Cipher/Mode/GCM.h
index 8f295a9f5f0..994fd609c15 100644
--- a/Userland/Libraries/LibCrypto/Cipher/Mode/GCM.h
+++ b/Userland/Libraries/LibCrypto/Cipher/Mode/GCM.h
@@ -15,7 +15,7 @@
 #include <LibCrypto/Verification.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::Cipher {
@@ -44,12 +44,12 @@ public:
     }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         StringBuilder builder;
         builder.append(this->cipher().class_name());
         builder.append("_GCM"sv);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 #endif
 
diff --git a/Userland/Libraries/LibCrypto/Cipher/Mode/Mode.h b/Userland/Libraries/LibCrypto/Cipher/Mode/Mode.h
index 6c8e554727c..c74a57fc1d0 100644
--- a/Userland/Libraries/LibCrypto/Cipher/Mode/Mode.h
+++ b/Userland/Libraries/LibCrypto/Cipher/Mode/Mode.h
@@ -34,7 +34,7 @@ public:
     }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const = 0;
+    virtual ByteString class_name() const = 0;
 #endif
 
     T& cipher()
diff --git a/Userland/Libraries/LibCrypto/Hash/BLAKE2b.h b/Userland/Libraries/LibCrypto/Hash/BLAKE2b.h
index 463bbe233b4..756616a3bb2 100644
--- a/Userland/Libraries/LibCrypto/Hash/BLAKE2b.h
+++ b/Userland/Libraries/LibCrypto/Hash/BLAKE2b.h
@@ -10,7 +10,7 @@
 #include <LibCrypto/Hash/SHA2.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::Hash {
@@ -44,7 +44,7 @@ public:
     static DigestType hash(StringView buffer) { return hash((u8 const*)buffer.characters_without_null_termination(), buffer.length()); }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         return "BLAKE2b";
     }
diff --git a/Userland/Libraries/LibCrypto/Hash/HashFunction.h b/Userland/Libraries/LibCrypto/Hash/HashFunction.h
index 0ea0df7f357..4848b947a37 100644
--- a/Userland/Libraries/LibCrypto/Hash/HashFunction.h
+++ b/Userland/Libraries/LibCrypto/Hash/HashFunction.h
@@ -55,7 +55,7 @@ public:
     virtual void reset() = 0;
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const = 0;
+    virtual ByteString class_name() const = 0;
 #endif
 
 protected:
diff --git a/Userland/Libraries/LibCrypto/Hash/HashManager.h b/Userland/Libraries/LibCrypto/Hash/HashManager.h
index 9ff2bbd0ada..f2fc526877b 100644
--- a/Userland/Libraries/LibCrypto/Hash/HashManager.h
+++ b/Userland/Libraries/LibCrypto/Hash/HashManager.h
@@ -197,10 +197,10 @@ public:
     }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         return m_algorithm.visit(
-            [&](Empty const&) -> DeprecatedString { return "UninitializedHashManager"; },
+            [&](Empty const&) -> ByteString { return "UninitializedHashManager"; },
             [&](auto const& hash) { return hash.class_name(); });
     }
 #endif
diff --git a/Userland/Libraries/LibCrypto/Hash/MD5.h b/Userland/Libraries/LibCrypto/Hash/MD5.h
index 01b1dc1096a..a732dcb99a2 100644
--- a/Userland/Libraries/LibCrypto/Hash/MD5.h
+++ b/Userland/Libraries/LibCrypto/Hash/MD5.h
@@ -10,7 +10,7 @@
 #include <LibCrypto/Hash/HashFunction.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::Hash {
@@ -56,7 +56,7 @@ public:
     virtual DigestType peek() override;
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         return "MD5";
     }
diff --git a/Userland/Libraries/LibCrypto/Hash/SHA1.h b/Userland/Libraries/LibCrypto/Hash/SHA1.h
index e85a910878e..d70e5fc7b32 100644
--- a/Userland/Libraries/LibCrypto/Hash/SHA1.h
+++ b/Userland/Libraries/LibCrypto/Hash/SHA1.h
@@ -9,7 +9,7 @@
 #include <LibCrypto/Hash/HashFunction.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::Hash {
@@ -52,7 +52,7 @@ public:
     static DigestType hash(StringView buffer) { return hash((u8 const*)buffer.characters_without_null_termination(), buffer.length()); }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         return "SHA1";
     }
diff --git a/Userland/Libraries/LibCrypto/Hash/SHA2.h b/Userland/Libraries/LibCrypto/Hash/SHA2.h
index f17c8e7aa09..87509ae0211 100644
--- a/Userland/Libraries/LibCrypto/Hash/SHA2.h
+++ b/Userland/Libraries/LibCrypto/Hash/SHA2.h
@@ -10,7 +10,7 @@
 #include <LibCrypto/Hash/HashFunction.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::Hash {
@@ -100,9 +100,9 @@ public:
     static DigestType hash(StringView buffer) { return hash((u8 const*)buffer.characters_without_null_termination(), buffer.length()); }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
-        return DeprecatedString::formatted("SHA{}", DigestSize * 8);
+        return ByteString::formatted("SHA{}", DigestSize * 8);
     }
 #endif
 
@@ -152,9 +152,9 @@ public:
     static DigestType hash(StringView buffer) { return hash((u8 const*)buffer.characters_without_null_termination(), buffer.length()); }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
-        return DeprecatedString::formatted("SHA{}", DigestSize * 8);
+        return ByteString::formatted("SHA{}", DigestSize * 8);
     }
 #endif
 
@@ -204,9 +204,9 @@ public:
     static DigestType hash(StringView buffer) { return hash((u8 const*)buffer.characters_without_null_termination(), buffer.length()); }
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
-        return DeprecatedString::formatted("SHA{}", DigestSize * 8);
+        return ByteString::formatted("SHA{}", DigestSize * 8);
     }
 #endif
 
diff --git a/Userland/Libraries/LibCrypto/PK/PK.h b/Userland/Libraries/LibCrypto/PK/PK.h
index 6a4ffaad24c..129328ec3ef 100644
--- a/Userland/Libraries/LibCrypto/PK/PK.h
+++ b/Userland/Libraries/LibCrypto/PK/PK.h
@@ -9,7 +9,7 @@
 #include <AK/ByteBuffer.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace Crypto::PK {
@@ -36,7 +36,7 @@ public:
     virtual void verify(ReadonlyBytes in, Bytes& out) = 0;
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const = 0;
+    virtual ByteString class_name() const = 0;
 #endif
 
     virtual size_t output_size() const = 0;
diff --git a/Userland/Libraries/LibCrypto/PK/RSA.h b/Userland/Libraries/LibCrypto/PK/RSA.h
index bfc7c9a368a..15229b451f5 100644
--- a/Userland/Libraries/LibCrypto/PK/RSA.h
+++ b/Userland/Libraries/LibCrypto/PK/RSA.h
@@ -162,7 +162,7 @@ public:
     virtual void verify(ReadonlyBytes in, Bytes& out) override;
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         return "RSA";
     }
@@ -214,7 +214,7 @@ public:
     virtual void verify(ReadonlyBytes, Bytes&) override;
 
 #ifndef KERNEL
-    virtual DeprecatedString class_name() const override
+    virtual ByteString class_name() const override
     {
         return "RSA_PKCS1-EME";
     }
diff --git a/Userland/Libraries/LibDNS/Answer.cpp b/Userland/Libraries/LibDNS/Answer.cpp
index eb8d86e1746..68c1ce983a5 100644
--- a/Userland/Libraries/LibDNS/Answer.cpp
+++ b/Userland/Libraries/LibDNS/Answer.cpp
@@ -11,7 +11,7 @@
 
 namespace DNS {
 
-Answer::Answer(Name const& name, RecordType type, RecordClass class_code, u32 ttl, DeprecatedString const& record_data, bool mdns_cache_flush)
+Answer::Answer(Name const& name, RecordType type, RecordClass class_code, u32 ttl, ByteString const& record_data, bool mdns_cache_flush)
     : m_name(name)
     , m_type(type)
     , m_class_code(class_code)
@@ -115,11 +115,11 @@ ErrorOr<void> encode(Encoder& encoder, DNS::Answer const& answer)
 template<>
 ErrorOr<DNS::Answer> decode(Decoder& decoder)
 {
-    auto name = TRY(decoder.decode<DeprecatedString>());
+    auto name = TRY(decoder.decode<ByteString>());
     auto record_type = TRY(decoder.decode<DNS::RecordType>());
     auto class_code = TRY(decoder.decode<DNS::RecordClass>());
     auto ttl = TRY(decoder.decode<u32>());
-    auto record_data = TRY(decoder.decode<DeprecatedString>());
+    auto record_data = TRY(decoder.decode<ByteString>());
     auto cache_flush = TRY(decoder.decode<bool>());
 
     return DNS::Answer { name, record_type, class_code, ttl, record_data, cache_flush };
diff --git a/Userland/Libraries/LibDNS/Answer.h b/Userland/Libraries/LibDNS/Answer.h
index 73263315dbd..f7b49414b56 100644
--- a/Userland/Libraries/LibDNS/Answer.h
+++ b/Userland/Libraries/LibDNS/Answer.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include "Name.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/Traits.h>
 #include <AK/Types.h>
@@ -36,7 +36,7 @@ enum class RecordClass : u16 {
 class Answer {
 public:
     Answer() = default;
-    Answer(Name const& name, RecordType type, RecordClass class_code, u32 ttl, DeprecatedString const& record_data, bool mdns_cache_flush);
+    Answer(Name const& name, RecordType type, RecordClass class_code, u32 ttl, ByteString const& record_data, bool mdns_cache_flush);
 
     Name const& name() const { return m_name; }
     RecordType type() const { return m_type; }
@@ -44,7 +44,7 @@ public:
     u16 raw_class_code() const { return (u16)m_class_code | (m_mdns_cache_flush ? MDNS_CACHE_FLUSH : 0); }
     u32 ttl() const { return m_ttl; }
     time_t received_time() const { return m_received_time; }
-    DeprecatedString const& record_data() const { return m_record_data; }
+    ByteString const& record_data() const { return m_record_data; }
     bool mdns_cache_flush() const { return m_mdns_cache_flush; }
 
     bool has_expired() const;
@@ -58,7 +58,7 @@ private:
     RecordClass m_class_code { 0 };
     u32 m_ttl { 0 };
     time_t m_received_time { 0 };
-    DeprecatedString m_record_data;
+    ByteString m_record_data;
     bool m_mdns_cache_flush { false };
 };
 
diff --git a/Userland/Libraries/LibDNS/Name.cpp b/Userland/Libraries/LibDNS/Name.cpp
index 0dfef512e3d..f0627f44926 100644
--- a/Userland/Libraries/LibDNS/Name.cpp
+++ b/Userland/Libraries/LibDNS/Name.cpp
@@ -13,7 +13,7 @@
 
 namespace DNS {
 
-Name::Name(DeprecatedString const& name)
+Name::Name(ByteString const& name)
 {
     if (name.ends_with('.'))
         m_name = name.substring(0, name.length() - 1);
@@ -38,7 +38,7 @@ ErrorOr<Name> Name::parse(ReadonlyBytes data, size_t& offset, size_t recursion_l
             if (builder.length() > MAX_NAME_SIZE)
                 return Error::from_string_literal("Domain name exceeds maximum allowed length");
             // This terminates the name.
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         } else if ((b & 0xc0) == 0xc0) {
             // The two bytes tell us the offset when to continue from.
             if (offset >= data.size())
@@ -48,7 +48,7 @@ ErrorOr<Name> Name::parse(ReadonlyBytes data, size_t& offset, size_t recursion_l
             builder.append(rest_of_name.as_string());
             if (builder.length() > MAX_NAME_SIZE)
                 return Error::from_string_literal("Domain name exceeds maximum allowed length");
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         } else {
             // This is the length of a part.
             if (offset + b >= data.size())
@@ -84,7 +84,7 @@ void Name::randomize_case()
         }
         builder.append(c);
     }
-    m_name = builder.to_deprecated_string();
+    m_name = builder.to_byte_string();
 }
 
 ErrorOr<void> Name::write_to_stream(Stream& stream) const
diff --git a/Userland/Libraries/LibDNS/Name.h b/Userland/Libraries/LibDNS/Name.h
index 66b8ceb28e5..29bbd39a496 100644
--- a/Userland/Libraries/LibDNS/Name.h
+++ b/Userland/Libraries/LibDNS/Name.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 
 namespace DNS {
@@ -15,12 +15,12 @@ namespace DNS {
 class Name {
 public:
     Name() = default;
-    Name(DeprecatedString const&);
+    Name(ByteString const&);
 
     static ErrorOr<Name> parse(ReadonlyBytes data, size_t& offset, size_t recursion_level = 0);
 
     size_t serialized_size() const;
-    DeprecatedString const& as_string() const { return m_name; }
+    ByteString const& as_string() const { return m_name; }
     ErrorOr<void> write_to_stream(Stream&) const;
 
     void randomize_case();
@@ -34,7 +34,7 @@ public:
     };
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
 };
 
 }
diff --git a/Userland/Libraries/LibDNS/Packet.cpp b/Userland/Libraries/LibDNS/Packet.cpp
index 8250f1efaf8..e829eaaf380 100644
--- a/Userland/Libraries/LibDNS/Packet.cpp
+++ b/Userland/Libraries/LibDNS/Packet.cpp
@@ -150,7 +150,7 @@ ErrorOr<Packet> Packet::from_raw_packet(ReadonlyBytes bytes)
         if (record.data_length() > bytes.size() - offset)
             return Error::from_string_literal("Unexpected EOF when parsing DNS packet");
 
-        DeprecatedString data;
+        ByteString data;
 
         switch ((RecordType)record.type()) {
         case RecordType::PTR: {
diff --git a/Userland/Libraries/LibDebug/DebugInfo.cpp b/Userland/Libraries/LibDebug/DebugInfo.cpp
index 71b0b0a4dec..ae885347aee 100644
--- a/Userland/Libraries/LibDebug/DebugInfo.cpp
+++ b/Userland/Libraries/LibDebug/DebugInfo.cpp
@@ -13,7 +13,7 @@
 
 namespace Debug {
 
-DebugInfo::DebugInfo(ELF::Image const& elf, DeprecatedString source_root, FlatPtr base_address)
+DebugInfo::DebugInfo(ELF::Image const& elf, ByteString source_root, FlatPtr base_address)
     : m_elf(elf)
     , m_source_root(move(source_root))
     , m_base_address(base_address)
@@ -91,8 +91,8 @@ ErrorOr<void> DebugInfo::prepare_lines()
         return {};
     }));
 
-    HashMap<DeprecatedFlyString, Optional<DeprecatedString>> memoized_full_paths;
-    auto compute_full_path = [&](DeprecatedFlyString const& file_path) -> Optional<DeprecatedString> {
+    HashMap<DeprecatedFlyString, Optional<ByteString>> memoized_full_paths;
+    auto compute_full_path = [&](DeprecatedFlyString const& file_path) -> Optional<ByteString> {
         if (file_path.view().contains("Toolchain/"sv) || file_path.view().contains("libgcc"sv))
             return {};
         if (file_path.view().starts_with("./"sv) && !m_source_root.is_empty())
@@ -135,11 +135,11 @@ Optional<DebugInfo::SourcePosition> DebugInfo::get_source_position(FlatPtr targe
     return {};
 }
 
-Optional<DebugInfo::SourcePositionAndAddress> DebugInfo::get_address_from_source_position(DeprecatedString const& file, size_t line) const
+Optional<DebugInfo::SourcePositionAndAddress> DebugInfo::get_address_from_source_position(ByteString const& file, size_t line) const
 {
-    DeprecatedString file_path = file;
+    ByteString file_path = file;
     if (!file_path.starts_with('/'))
-        file_path = DeprecatedString::formatted("/{}", file_path);
+        file_path = ByteString::formatted("/{}", file_path);
 
     Optional<SourcePositionAndAddress> result;
     for (auto const& line_entry : m_sorted_lines) {
@@ -327,10 +327,10 @@ ErrorOr<void> DebugInfo::add_type_info_to_variable(Dwarf::DIE const& type_die, P
             array_type_name.append(type_info->type_name);
             for (auto array_size : type_info->dimension_sizes) {
                 array_type_name.append('[');
-                array_type_name.append(DeprecatedString::formatted("{:d}", array_size));
+                array_type_name.append(ByteString::formatted("{:d}", array_size));
                 array_type_name.append(']');
             }
-            parent_variable->type_name = array_type_name.to_deprecated_string();
+            parent_variable->type_name = array_type_name.to_byte_string();
         }
         parent_variable->type = move(type_info);
         parent_variable->type->type_tag = type_die.tag();
@@ -350,7 +350,7 @@ bool DebugInfo::is_variable_tag_supported(Dwarf::EntryTag const& tag)
         || tag == Dwarf::EntryTag::ArrayType;
 }
 
-DeprecatedString DebugInfo::name_of_containing_function(FlatPtr address) const
+ByteString DebugInfo::name_of_containing_function(FlatPtr address) const
 {
     auto function = get_containing_function(address);
     if (!function.has_value())
@@ -408,7 +408,7 @@ ErrorOr<DebugInfo::SourcePositionWithInlines> DebugInfo::get_source_position_wit
             return {};
         }
 
-        inline_chain.append({ DeprecatedString::formatted("{}/{}", caller_source_path->directory, caller_source_path->filename), caller_line.value() });
+        inline_chain.append({ ByteString::formatted("{}/{}", caller_source_path->directory, caller_source_path->filename), caller_line.value() });
         return {};
     };
 
diff --git a/Userland/Libraries/LibDebug/DebugInfo.h b/Userland/Libraries/LibDebug/DebugInfo.h
index 6c344cae266..1fc11492d7f 100644
--- a/Userland/Libraries/LibDebug/DebugInfo.h
+++ b/Userland/Libraries/LibDebug/DebugInfo.h
@@ -23,7 +23,7 @@ class DebugInfo {
     AK_MAKE_NONMOVABLE(DebugInfo);
 
 public:
-    explicit DebugInfo(ELF::Image const&, DeprecatedString source_root = {}, FlatPtr base_address = 0);
+    explicit DebugInfo(ELF::Image const&, ByteString source_root = {}, FlatPtr base_address = 0);
 
     ELF::Image const& elf() const { return m_elf; }
 
@@ -33,15 +33,15 @@ public:
         Optional<FlatPtr> address_of_first_statement;
 
         SourcePosition()
-            : SourcePosition(DeprecatedString::empty(), 0)
+            : SourcePosition(ByteString::empty(), 0)
         {
         }
-        SourcePosition(DeprecatedString file_path, size_t line_number)
+        SourcePosition(ByteString file_path, size_t line_number)
             : file_path(file_path)
             , line_number(line_number)
         {
         }
-        SourcePosition(DeprecatedString file_path, size_t line_number, FlatPtr address_of_first_statement)
+        SourcePosition(ByteString file_path, size_t line_number, FlatPtr address_of_first_statement)
             : file_path(file_path)
             , line_number(line_number)
             , address_of_first_statement(address_of_first_statement)
@@ -59,8 +59,8 @@ public:
             Address,
             Register,
         };
-        DeprecatedString name;
-        DeprecatedString type_name;
+        ByteString name;
+        ByteString type_name;
         LocationType location_type { LocationType::None };
         union {
             FlatPtr address;
@@ -83,7 +83,7 @@ public:
 
     struct VariablesScope {
         bool is_function { false };
-        DeprecatedString name;
+        ByteString name;
         FlatPtr address_low { 0 };
         FlatPtr address_high { 0 }; // Non-inclusive - the lowest address after address_low that's not in this scope
         Vector<Dwarf::DIE> dies_of_variables;
@@ -100,14 +100,14 @@ public:
     ErrorOr<SourcePositionWithInlines> get_source_position_with_inlines(FlatPtr address) const;
 
     struct SourcePositionAndAddress {
-        DeprecatedString file;
+        ByteString file;
         size_t line;
         FlatPtr address;
     };
 
-    Optional<SourcePositionAndAddress> get_address_from_source_position(DeprecatedString const& file, size_t line) const;
+    Optional<SourcePositionAndAddress> get_address_from_source_position(ByteString const& file, size_t line) const;
 
-    DeprecatedString name_of_containing_function(FlatPtr address) const;
+    ByteString name_of_containing_function(FlatPtr address) const;
     Vector<SourcePosition> source_lines_in_scope(VariablesScope const&) const;
     Optional<VariablesScope> get_containing_function(FlatPtr address) const;
 
@@ -123,7 +123,7 @@ private:
     ErrorOr<Optional<uint32_t>> get_line_of_inline(Dwarf::DIE const&) const;
 
     ELF::Image const& m_elf;
-    DeprecatedString m_source_root;
+    ByteString m_source_root;
     FlatPtr m_base_address { 0 };
     Dwarf::DwarfInfo m_dwarf_info;
 
diff --git a/Userland/Libraries/LibDebug/DebugSession.cpp b/Userland/Libraries/LibDebug/DebugSession.cpp
index f9974d04e98..d6b0761a451 100644
--- a/Userland/Libraries/LibDebug/DebugSession.cpp
+++ b/Userland/Libraries/LibDebug/DebugSession.cpp
@@ -17,7 +17,7 @@
 
 namespace Debug {
 
-DebugSession::DebugSession(pid_t pid, DeprecatedString source_root, Function<void(float)> on_initialization_progress)
+DebugSession::DebugSession(pid_t pid, ByteString source_root, Function<void(float)> on_initialization_progress)
     : m_debuggee_pid(pid)
     , m_source_root(source_root)
     , m_on_initialization_progress(move(on_initialization_progress))
@@ -53,8 +53,8 @@ void DebugSession::for_each_loaded_library(Function<IterationDecision(LoadedLibr
     }
 }
 
-OwnPtr<DebugSession> DebugSession::exec_and_attach(DeprecatedString const& command,
-    DeprecatedString source_root,
+OwnPtr<DebugSession> DebugSession::exec_and_attach(ByteString const& command,
+    ByteString source_root,
     Function<ErrorOr<void>()> setup_child,
     Function<void(float)> on_initialization_progress)
 {
@@ -134,7 +134,7 @@ OwnPtr<DebugSession> DebugSession::exec_and_attach(DeprecatedString const& comma
     return debug_session;
 }
 
-OwnPtr<DebugSession> DebugSession::attach(pid_t pid, DeprecatedString source_root, Function<void(float)> on_initialization_progress)
+OwnPtr<DebugSession> DebugSession::attach(pid_t pid, ByteString source_root, Function<void(float)> on_initialization_progress)
 {
     if (ptrace(PT_ATTACH, pid, 0, 0) < 0) {
         perror("PT_ATTACH");
@@ -415,7 +415,7 @@ void DebugSession::detach()
     continue_debuggee();
 }
 
-Optional<DebugSession::InsertBreakpointAtSymbolResult> DebugSession::insert_breakpoint(DeprecatedString const& symbol_name)
+Optional<DebugSession::InsertBreakpointAtSymbolResult> DebugSession::insert_breakpoint(ByteString const& symbol_name)
 {
     Optional<InsertBreakpointAtSymbolResult> result;
     for_each_loaded_library([this, symbol_name, &result](auto& lib) {
@@ -438,7 +438,7 @@ Optional<DebugSession::InsertBreakpointAtSymbolResult> DebugSession::insert_brea
     return result;
 }
 
-Optional<DebugSession::InsertBreakpointAtSourcePositionResult> DebugSession::insert_breakpoint(DeprecatedString const& filename, size_t line_number)
+Optional<DebugSession::InsertBreakpointAtSourcePositionResult> DebugSession::insert_breakpoint(ByteString const& filename, size_t line_number)
 {
     auto address_and_source_position = get_address_from_source_position(filename, line_number);
     if (!address_and_source_position.has_value())
@@ -466,17 +466,17 @@ ErrorOr<void> DebugSession::update_loaded_libs()
     auto const& vm_entries = json.as_array();
     Regex<PosixExtended> segment_name_re("(.+): ");
 
-    auto get_path_to_object = [&segment_name_re](DeprecatedString const& vm_name) -> Optional<DeprecatedString> {
+    auto get_path_to_object = [&segment_name_re](ByteString const& vm_name) -> Optional<ByteString> {
         if (vm_name == "/usr/lib/Loader.so")
             return vm_name;
         RegexResult result;
         auto rc = segment_name_re.search(vm_name, result);
         if (!rc)
             return {};
-        auto lib_name = result.capture_group_matches.at(0).at(0).view.string_view().to_deprecated_string();
+        auto lib_name = result.capture_group_matches.at(0).at(0).view.string_view().to_byte_string();
         if (lib_name.starts_with('/'))
             return lib_name;
-        return DeprecatedString::formatted("/usr/lib/{}", lib_name);
+        return ByteString::formatted("/usr/lib/{}", lib_name);
     };
 
     ScopeGuard progress_guard([this]() {
@@ -492,13 +492,13 @@ ErrorOr<void> DebugSession::update_loaded_libs()
             m_on_initialization_progress(vm_entry_index / static_cast<float>(vm_entries.size()));
 
         // TODO: check that region is executable
-        auto vm_name = entry.as_object().get_deprecated_string("name"sv).value();
+        auto vm_name = entry.as_object().get_byte_string("name"sv).value();
 
         auto object_path = get_path_to_object(vm_name);
         if (!object_path.has_value())
             return IterationDecision::Continue;
 
-        DeprecatedString lib_name = object_path.value();
+        ByteString lib_name = object_path.value();
         if (FileSystem::looks_like_shared_library(lib_name))
             lib_name = LexicalPath::basename(object_path.value());
 
diff --git a/Userland/Libraries/LibDebug/DebugSession.h b/Userland/Libraries/LibDebug/DebugSession.h
index 24990ffeeea..cc1aef27c43 100644
--- a/Userland/Libraries/LibDebug/DebugSession.h
+++ b/Userland/Libraries/LibDebug/DebugSession.h
@@ -6,8 +6,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/Demangle.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/NonnullRefPtr.h>
@@ -27,8 +27,8 @@ namespace Debug {
 
 class DebugSession : public ProcessInspector {
 public:
-    static OwnPtr<DebugSession> exec_and_attach(DeprecatedString const& command, DeprecatedString source_root = {}, Function<ErrorOr<void>()> setup_child = {}, Function<void(float)> on_initialization_progress = {});
-    static OwnPtr<DebugSession> attach(pid_t pid, DeprecatedString source_root = {}, Function<void(float)> on_initialization_progress = {});
+    static OwnPtr<DebugSession> exec_and_attach(ByteString const& command, ByteString source_root = {}, Function<ErrorOr<void>()> setup_child = {}, Function<void(float)> on_initialization_progress = {});
+    static OwnPtr<DebugSession> attach(pid_t pid, ByteString source_root = {}, Function<void(float)> on_initialization_progress = {});
 
     virtual ~DebugSession() override;
 
@@ -56,20 +56,20 @@ public:
     };
 
     struct InsertBreakpointAtSymbolResult {
-        DeprecatedString library_name;
+        ByteString library_name;
         FlatPtr address { 0 };
     };
 
-    Optional<InsertBreakpointAtSymbolResult> insert_breakpoint(DeprecatedString const& symbol_name);
+    Optional<InsertBreakpointAtSymbolResult> insert_breakpoint(ByteString const& symbol_name);
 
     struct InsertBreakpointAtSourcePositionResult {
-        DeprecatedString library_name;
-        DeprecatedString filename;
+        ByteString library_name;
+        ByteString filename;
         size_t line_number { 0 };
         FlatPtr address { 0 };
     };
 
-    Optional<InsertBreakpointAtSourcePositionResult> insert_breakpoint(DeprecatedString const& filename, size_t line_number);
+    Optional<InsertBreakpointAtSourcePositionResult> insert_breakpoint(ByteString const& filename, size_t line_number);
 
     bool insert_breakpoint(FlatPtr address);
     bool disable_breakpoint(FlatPtr address);
@@ -132,7 +132,7 @@ public:
     };
 
 private:
-    explicit DebugSession(pid_t, DeprecatedString source_root, Function<void(float)> on_initialization_progress = {});
+    explicit DebugSession(pid_t, ByteString source_root, Function<void(float)> on_initialization_progress = {});
 
     // x86 breakpoint instruction "int3"
     static constexpr u8 BREAKPOINT_INSTRUCTION = 0xcc;
@@ -140,14 +140,14 @@ private:
     ErrorOr<void> update_loaded_libs();
 
     int m_debuggee_pid { -1 };
-    DeprecatedString m_source_root;
+    ByteString m_source_root;
     bool m_is_debuggee_dead { false };
 
     HashMap<FlatPtr, BreakPoint> m_breakpoints;
     HashMap<FlatPtr, WatchPoint> m_watchpoints;
 
     // Maps from library name to LoadedLibrary object
-    HashMap<DeprecatedString, NonnullOwnPtr<LoadedLibrary>> m_loaded_libraries;
+    HashMap<ByteString, NonnullOwnPtr<LoadedLibrary>> m_loaded_libraries;
 
     Function<void(float)> m_on_initialization_progress;
 };
diff --git a/Userland/Libraries/LibDebug/Dwarf/LineProgram.cpp b/Userland/Libraries/LibDebug/Dwarf/LineProgram.cpp
index 8ca4e4c5a40..5c0d2626c47 100644
--- a/Userland/Libraries/LibDebug/Dwarf/LineProgram.cpp
+++ b/Userland/Libraries/LibDebug/Dwarf/LineProgram.cpp
@@ -81,7 +81,7 @@ ErrorOr<void> LineProgram::parse_path_entries(Function<void(PathEntry& entry)> c
             StringBuilder builder;
             while (auto c = TRY(m_stream.read_value<char>()))
                 TRY(builder.try_append(c));
-            auto path = builder.to_deprecated_string();
+            auto path = builder.to_byte_string();
             if (path.length() == 0)
                 break;
             dbgln_if(DWARF_DEBUG, "path: {}", path);
diff --git a/Userland/Libraries/LibDebug/Dwarf/LineProgram.h b/Userland/Libraries/LibDebug/Dwarf/LineProgram.h
index 69ce47b50c0..74061af564b 100644
--- a/Userland/Libraries/LibDebug/Dwarf/LineProgram.h
+++ b/Userland/Libraries/LibDebug/Dwarf/LineProgram.h
@@ -95,7 +95,7 @@ struct PathEntryFormat {
 };
 
 struct PathEntry {
-    DeprecatedString path;
+    ByteString path;
     size_t directory_index { 0 };
 };
 
@@ -180,7 +180,7 @@ private:
 
     size_t m_unit_offset { 0 };
     LineProgramUnitHeader32 m_unit_header {};
-    Vector<DeprecatedString> m_source_directories;
+    Vector<ByteString> m_source_directories;
     Vector<FileEntry> m_source_files;
 
     // The registers of the "line program" virtual machine
diff --git a/Userland/Libraries/LibDebug/LoadedLibrary.h b/Userland/Libraries/LibDebug/LoadedLibrary.h
index 658b31b435e..f8efef2b62a 100644
--- a/Userland/Libraries/LibDebug/LoadedLibrary.h
+++ b/Userland/Libraries/LibDebug/LoadedLibrary.h
@@ -13,13 +13,13 @@
 
 namespace Debug {
 struct LoadedLibrary {
-    DeprecatedString name;
+    ByteString name;
     NonnullOwnPtr<Core::MappedFile> file;
     NonnullOwnPtr<ELF::Image> image;
     NonnullOwnPtr<DebugInfo> debug_info;
     FlatPtr base_address {};
 
-    LoadedLibrary(DeprecatedString const& name, NonnullOwnPtr<Core::MappedFile> file, NonnullOwnPtr<ELF::Image> image, NonnullOwnPtr<DebugInfo>&& debug_info, FlatPtr base_address)
+    LoadedLibrary(ByteString const& name, NonnullOwnPtr<Core::MappedFile> file, NonnullOwnPtr<ELF::Image> image, NonnullOwnPtr<DebugInfo>&& debug_info, FlatPtr base_address)
         : name(name)
         , file(move(file))
         , image(move(image))
diff --git a/Userland/Libraries/LibDebug/ProcessInspector.cpp b/Userland/Libraries/LibDebug/ProcessInspector.cpp
index a627a14f9de..5a564d97577 100644
--- a/Userland/Libraries/LibDebug/ProcessInspector.cpp
+++ b/Userland/Libraries/LibDebug/ProcessInspector.cpp
@@ -27,12 +27,12 @@ Optional<ProcessInspector::SymbolicationResult> ProcessInspector::symbolicate(Fl
     auto* lib = library_at(address);
     if (!lib)
         return {};
-    // FIXME: ELF::Image symbolicate() API should return DeprecatedString::empty() if symbol is not found (It currently returns ??)
+    // FIXME: ELF::Image symbolicate() API should return ByteString::empty() if symbol is not found (It currently returns ??)
     auto symbol = lib->debug_info->elf().symbolicate(address - lib->base_address);
     return { { lib->name, symbol } };
 }
 
-Optional<DebugInfo::SourcePositionAndAddress> ProcessInspector::get_address_from_source_position(DeprecatedString const& file, size_t line) const
+Optional<DebugInfo::SourcePositionAndAddress> ProcessInspector::get_address_from_source_position(ByteString const& file, size_t line) const
 {
     Optional<DebugInfo::SourcePositionAndAddress> result;
     for_each_loaded_library([file, line, &result](auto& lib) {
diff --git a/Userland/Libraries/LibDebug/ProcessInspector.h b/Userland/Libraries/LibDebug/ProcessInspector.h
index 8247f6bb193..4b6a388ae22 100644
--- a/Userland/Libraries/LibDebug/ProcessInspector.h
+++ b/Userland/Libraries/LibDebug/ProcessInspector.h
@@ -24,11 +24,11 @@ public:
 
     LoadedLibrary const* library_at(FlatPtr address) const;
     struct SymbolicationResult {
-        DeprecatedString library_name;
-        DeprecatedString symbol;
+        ByteString library_name;
+        ByteString symbol;
     };
     Optional<SymbolicationResult> symbolicate(FlatPtr address) const;
-    Optional<DebugInfo::SourcePositionAndAddress> get_address_from_source_position(DeprecatedString const& file, size_t line) const;
+    Optional<DebugInfo::SourcePositionAndAddress> get_address_from_source_position(ByteString const& file, size_t line) const;
     Optional<DebugInfo::SourcePosition> get_source_position(FlatPtr address) const;
 
 protected:
diff --git a/Userland/Libraries/LibDesktop/AppFile.cpp b/Userland/Libraries/LibDesktop/AppFile.cpp
index 00633f8e4f9..635682703d0 100644
--- a/Userland/Libraries/LibDesktop/AppFile.cpp
+++ b/Userland/Libraries/LibDesktop/AppFile.cpp
@@ -16,9 +16,9 @@
 
 namespace Desktop {
 
-DeprecatedString AppFile::app_file_path_for_app(StringView app_name)
+ByteString AppFile::app_file_path_for_app(StringView app_name)
 {
-    return DeprecatedString::formatted("{}/{}.af", APP_FILES_DIRECTORY, app_name);
+    return ByteString::formatted("{}/{}.af", APP_FILES_DIRECTORY, app_name);
 }
 
 bool AppFile::exists_for_app(StringView app_name)
@@ -45,7 +45,7 @@ void AppFile::for_each(Function<void(NonnullRefPtr<AppFile>)> callback, StringVi
         auto name = di.next_path();
         if (!name.ends_with(".af"sv))
             continue;
-        auto path = DeprecatedString::formatted("{}/{}", directory, name);
+        auto path = ByteString::formatted("{}/{}", directory, name);
         auto af = AppFile::open(path);
         if (!af->is_valid())
             continue;
@@ -68,36 +68,36 @@ bool AppFile::validate() const
     return true;
 }
 
-DeprecatedString AppFile::name() const
+ByteString AppFile::name() const
 {
     auto name = m_config->read_entry("App", "Name").trim_whitespace();
     VERIFY(!name.is_empty());
     return name;
 }
 
-DeprecatedString AppFile::executable() const
+ByteString AppFile::executable() const
 {
     auto executable = m_config->read_entry("App", "Executable").trim_whitespace();
     VERIFY(!executable.is_empty());
     return executable;
 }
 
-DeprecatedString AppFile::description() const
+ByteString AppFile::description() const
 {
     return m_config->read_entry("App", "Description").trim_whitespace();
 }
 
-DeprecatedString AppFile::category() const
+ByteString AppFile::category() const
 {
     return m_config->read_entry("App", "Category").trim_whitespace();
 }
 
-DeprecatedString AppFile::working_directory() const
+ByteString AppFile::working_directory() const
 {
     return m_config->read_entry("App", "WorkingDirectory").trim_whitespace();
 }
 
-DeprecatedString AppFile::icon_path() const
+ByteString AppFile::icon_path() const
 {
     return m_config->read_entry("App", "IconPath").trim_whitespace();
 }
@@ -127,9 +127,9 @@ bool AppFile::exclude_from_system_menu() const
     return m_config->read_bool_entry("App", "ExcludeFromSystemMenu", false);
 }
 
-Vector<DeprecatedString> AppFile::launcher_mime_types() const
+Vector<ByteString> AppFile::launcher_mime_types() const
 {
-    Vector<DeprecatedString> mime_types;
+    Vector<ByteString> mime_types;
     for (auto& entry : m_config->read_entry("Launcher", "MimeTypes").split(',')) {
         entry = entry.trim_whitespace();
         if (!entry.is_empty())
@@ -138,9 +138,9 @@ Vector<DeprecatedString> AppFile::launcher_mime_types() const
     return mime_types;
 }
 
-Vector<DeprecatedString> AppFile::launcher_file_types() const
+Vector<ByteString> AppFile::launcher_file_types() const
 {
-    Vector<DeprecatedString> file_types;
+    Vector<ByteString> file_types;
     for (auto& entry : m_config->read_entry("Launcher", "FileTypes").split(',')) {
         entry = entry.trim_whitespace();
         if (!entry.is_empty())
@@ -149,9 +149,9 @@ Vector<DeprecatedString> AppFile::launcher_file_types() const
     return file_types;
 }
 
-Vector<DeprecatedString> AppFile::launcher_protocols() const
+Vector<ByteString> AppFile::launcher_protocols() const
 {
-    Vector<DeprecatedString> protocols;
+    Vector<ByteString> protocols;
     for (auto& entry : m_config->read_entry("Launcher", "Protocols").split(',')) {
         entry = entry.trim_whitespace();
         if (!entry.is_empty())
diff --git a/Userland/Libraries/LibDesktop/AppFile.h b/Userland/Libraries/LibDesktop/AppFile.h
index e132ea2cc66..1e1216d97cb 100644
--- a/Userland/Libraries/LibDesktop/AppFile.h
+++ b/Userland/Libraries/LibDesktop/AppFile.h
@@ -18,8 +18,8 @@ public:
     static constexpr auto APP_FILES_DIRECTORY = "/res/apps"sv;
 
     static bool exists_for_app(StringView app_name);
-    static DeprecatedString file_for_app(StringView app_name);
-    static DeprecatedString app_file_path_for_app(StringView app_name);
+    static ByteString file_for_app(StringView app_name);
+    static ByteString app_file_path_for_app(StringView app_name);
 
     static NonnullRefPtr<AppFile> get_for_app(StringView app_name);
     static NonnullRefPtr<AppFile> open(StringView path);
@@ -27,21 +27,21 @@ public:
     ~AppFile() = default;
 
     bool is_valid() const { return m_valid; }
-    DeprecatedString filename() const { return m_config->filename(); }
+    ByteString filename() const { return m_config->filename(); }
 
-    DeprecatedString name() const;
-    DeprecatedString executable() const;
-    DeprecatedString category() const;
-    DeprecatedString description() const;
-    DeprecatedString working_directory() const;
-    DeprecatedString icon_path() const;
+    ByteString name() const;
+    ByteString executable() const;
+    ByteString category() const;
+    ByteString description() const;
+    ByteString working_directory() const;
+    ByteString icon_path() const;
     GUI::Icon icon() const;
     bool run_in_terminal() const;
     bool requires_root() const;
     bool exclude_from_system_menu() const;
-    Vector<DeprecatedString> launcher_mime_types() const;
-    Vector<DeprecatedString> launcher_file_types() const;
-    Vector<DeprecatedString> launcher_protocols() const;
+    Vector<ByteString> launcher_mime_types() const;
+    Vector<ByteString> launcher_file_types() const;
+    Vector<ByteString> launcher_protocols() const;
     bool spawn(ReadonlySpan<StringView> arguments = {}) const;
 
 private:
diff --git a/Userland/Libraries/LibDesktop/Launcher.cpp b/Userland/Libraries/LibDesktop/Launcher.cpp
index de182ddfea7..c30d2c520f2 100644
--- a/Userland/Libraries/LibDesktop/Launcher.cpp
+++ b/Userland/Libraries/LibDesktop/Launcher.cpp
@@ -13,14 +13,14 @@
 
 namespace Desktop {
 
-auto Launcher::Details::from_details_str(DeprecatedString const& details_str) -> NonnullRefPtr<Details>
+auto Launcher::Details::from_details_str(ByteString const& details_str) -> NonnullRefPtr<Details>
 {
     auto details = adopt_ref(*new Details);
     auto json = JsonValue::from_string(details_str).release_value_but_fixme_should_propagate_errors();
     auto const& obj = json.as_object();
-    details->executable = obj.get_deprecated_string("executable"sv).value_or({});
-    details->name = obj.get_deprecated_string("name"sv).value_or({});
-    if (auto type_value = obj.get_deprecated_string("type"sv); type_value.has_value()) {
+    details->executable = obj.get_byte_string("executable"sv).value_or({});
+    details->name = obj.get_byte_string("name"sv).value_or({});
+    if (auto type_value = obj.get_byte_string("type"sv); type_value.has_value()) {
         auto const& type_str = type_value.value();
         if (type_str == "app")
             details->launcher_type = LauncherType::Application;
@@ -62,7 +62,7 @@ ErrorOr<void> Launcher::add_allowed_url(URL const& url)
     return {};
 }
 
-ErrorOr<void> Launcher::add_allowed_handler_with_any_url(DeprecatedString const& handler)
+ErrorOr<void> Launcher::add_allowed_handler_with_any_url(ByteString const& handler)
 {
     auto response_or_error = connection().try_add_allowed_handler_with_any_url(handler);
     if (response_or_error.is_error())
@@ -70,7 +70,7 @@ ErrorOr<void> Launcher::add_allowed_handler_with_any_url(DeprecatedString const&
     return {};
 }
 
-ErrorOr<void> Launcher::add_allowed_handler_with_only_specific_urls(DeprecatedString const& handler, Vector<URL> const& urls)
+ErrorOr<void> Launcher::add_allowed_handler_with_only_specific_urls(ByteString const& handler, Vector<URL> const& urls)
 {
     auto response_or_error = connection().try_add_allowed_handler_with_only_specific_urls(handler, urls);
     if (response_or_error.is_error())
@@ -86,7 +86,7 @@ ErrorOr<void> Launcher::seal_allowlist()
     return {};
 }
 
-bool Launcher::open(const URL& url, DeprecatedString const& handler_name)
+bool Launcher::open(const URL& url, ByteString const& handler_name)
 {
     return connection().open_url(url, handler_name);
 }
@@ -97,14 +97,14 @@ bool Launcher::open(const URL& url, Details const& details)
     return open(url, details.executable);
 }
 
-Vector<DeprecatedString> Launcher::get_handlers_for_url(const URL& url)
+Vector<ByteString> Launcher::get_handlers_for_url(const URL& url)
 {
-    return connection().get_handlers_for_url(url.to_deprecated_string());
+    return connection().get_handlers_for_url(url.to_byte_string());
 }
 
 auto Launcher::get_handlers_with_details_for_url(const URL& url) -> Vector<NonnullRefPtr<Details>>
 {
-    auto details = connection().get_handlers_with_details_for_url(url.to_deprecated_string());
+    auto details = connection().get_handlers_with_details_for_url(url.to_byte_string());
     Vector<NonnullRefPtr<Details>> handlers_with_details;
     for (auto& value : details) {
         handlers_with_details.append(Details::from_details_str(value));
diff --git a/Userland/Libraries/LibDesktop/Launcher.h b/Userland/Libraries/LibDesktop/Launcher.h
index 52f7a019ded..2ddddd306d4 100644
--- a/Userland/Libraries/LibDesktop/Launcher.h
+++ b/Userland/Libraries/LibDesktop/Launcher.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/HashMap.h>
 #include <AK/RefCounted.h>
@@ -23,21 +23,21 @@ public:
     };
 
     struct Details : public RefCounted<Details> {
-        DeprecatedString name;
-        DeprecatedString executable;
+        ByteString name;
+        ByteString executable;
         LauncherType launcher_type { LauncherType::Default };
 
-        static NonnullRefPtr<Details> from_details_str(DeprecatedString const&);
+        static NonnullRefPtr<Details> from_details_str(ByteString const&);
     };
 
     static void ensure_connection();
     static ErrorOr<void> add_allowed_url(URL const&);
-    static ErrorOr<void> add_allowed_handler_with_any_url(DeprecatedString const& handler);
-    static ErrorOr<void> add_allowed_handler_with_only_specific_urls(DeprecatedString const& handler, Vector<URL> const&);
+    static ErrorOr<void> add_allowed_handler_with_any_url(ByteString const& handler);
+    static ErrorOr<void> add_allowed_handler_with_only_specific_urls(ByteString const& handler, Vector<URL> const&);
     static ErrorOr<void> seal_allowlist();
-    static bool open(const URL&, DeprecatedString const& handler_name = {});
+    static bool open(const URL&, ByteString const& handler_name = {});
     static bool open(const URL&, Details const& details);
-    static Vector<DeprecatedString> get_handlers_for_url(const URL&);
+    static Vector<ByteString> get_handlers_for_url(const URL&);
     static Vector<NonnullRefPtr<Details>> get_handlers_with_details_for_url(const URL&);
 };
 
diff --git a/Userland/Libraries/LibDiff/Format.cpp b/Userland/Libraries/LibDiff/Format.cpp
index 7af72006f35..7fbb0b1bed8 100644
--- a/Userland/Libraries/LibDiff/Format.cpp
+++ b/Userland/Libraries/LibDiff/Format.cpp
@@ -8,14 +8,14 @@
 
 #include "Format.h"
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Stream.h>
 #include <AK/StringBuilder.h>
 #include <AK/Vector.h>
 #include <LibDiff/Hunks.h>
 
 namespace Diff {
-DeprecatedString generate_only_additions(StringView text)
+ByteString generate_only_additions(StringView text)
 {
     auto lines = text.split_view('\n', SplitBehavior::KeepEmpty);
     StringBuilder builder;
@@ -23,7 +23,7 @@ DeprecatedString generate_only_additions(StringView text)
     for (auto const& line : lines) {
         builder.appendff("+{}\n", line);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 ErrorOr<void> write_unified_header(StringView old_path, StringView new_path, Stream& stream)
diff --git a/Userland/Libraries/LibDiff/Format.h b/Userland/Libraries/LibDiff/Format.h
index 858e6d7c75d..7266e7b9244 100644
--- a/Userland/Libraries/LibDiff/Format.h
+++ b/Userland/Libraries/LibDiff/Format.h
@@ -13,7 +13,7 @@
 
 namespace Diff {
 
-DeprecatedString generate_only_additions(StringView);
+ByteString generate_only_additions(StringView);
 
 enum class ColorOutput {
     Yes,
diff --git a/Userland/Libraries/LibDiff/Hunks.cpp b/Userland/Libraries/LibDiff/Hunks.cpp
index 205b3d67783..3f3b9448e99 100644
--- a/Userland/Libraries/LibDiff/Hunks.cpp
+++ b/Userland/Libraries/LibDiff/Hunks.cpp
@@ -65,7 +65,7 @@ ErrorOr<String> Parser::parse_file_line(Optional<size_t> const& strip_count)
 
     // No strip count given. Default to basename of file.
     if (!strip_count.has_value())
-        return String::from_deprecated_string(LexicalPath::basename(path));
+        return String::from_byte_string(LexicalPath::basename(path));
 
     // NOTE: We cannot use LexicalPath::parts as we want to strip the non-canonicalized path.
     auto const& parts = path.split_view('/');
diff --git a/Userland/Libraries/LibEDID/DMT.cpp b/Userland/Libraries/LibEDID/DMT.cpp
index a145e3a0fa4..6ce87d36ead 100644
--- a/Userland/Libraries/LibEDID/DMT.cpp
+++ b/Userland/Libraries/LibEDID/DMT.cpp
@@ -7,7 +7,7 @@
 #include <LibEDID/DMT.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace EDID {
@@ -120,11 +120,11 @@ u32 DMT::MonitorTiming::refresh_rate_hz() const
 }
 
 #ifndef KERNEL
-DeprecatedString DMT::MonitorTiming::name() const
+ByteString DMT::MonitorTiming::name() const
 {
     if (scan_type == ScanType::Interlaced)
-        return DeprecatedString::formatted("{} x {} @ {}Hz (Interlaced)", horizontal_pixels, vertical_lines, refresh_rate_hz());
-    return DeprecatedString::formatted("{} x {} @ {}Hz", horizontal_pixels, vertical_lines, refresh_rate_hz());
+        return ByteString::formatted("{} x {} @ {}Hz (Interlaced)", horizontal_pixels, vertical_lines, refresh_rate_hz());
+    return ByteString::formatted("{} x {} @ {}Hz", horizontal_pixels, vertical_lines, refresh_rate_hz());
 }
 #endif
 
diff --git a/Userland/Libraries/LibEDID/DMT.h b/Userland/Libraries/LibEDID/DMT.h
index a5c7de82b80..10d50ce64f0 100644
--- a/Userland/Libraries/LibEDID/DMT.h
+++ b/Userland/Libraries/LibEDID/DMT.h
@@ -54,7 +54,7 @@ public:
         FixedPoint<16, u32> vertical_frequency_hz() const;
         u32 refresh_rate_hz() const;
 #ifndef KERNEL
-        DeprecatedString name() const;
+        ByteString name() const;
 #endif
     };
 
diff --git a/Userland/Libraries/LibEDID/EDID.cpp b/Userland/Libraries/LibEDID/EDID.cpp
index 940399643a1..0a2d3f1eaf9 100644
--- a/Userland/Libraries/LibEDID/EDID.cpp
+++ b/Userland/Libraries/LibEDID/EDID.cpp
@@ -227,7 +227,7 @@ ErrorOr<Parser> Parser::from_display_connector_device(int display_connector_fd)
     return from_bytes(move(edid_byte_buffer));
 }
 
-ErrorOr<Parser> Parser::from_display_connector_device(DeprecatedString const& display_connector_device)
+ErrorOr<Parser> Parser::from_display_connector_device(ByteString const& display_connector_device)
 {
     int display_connector_fd = open(display_connector_device.characters(), O_RDWR | O_CLOEXEC);
     if (display_connector_fd < 0) {
@@ -314,7 +314,7 @@ ErrorOr<void> Parser::parse()
 #ifdef KERNEL
     m_version = TRY(Kernel::KString::formatted("1.{}", (int)m_revision));
 #else
-    m_version = DeprecatedString::formatted("1.{}", (int)m_revision);
+    m_version = ByteString::formatted("1.{}", (int)m_revision);
 #endif
 
     u8 checksum = 0x0;
@@ -420,7 +420,7 @@ StringView Parser::legacy_manufacturer_id() const
 }
 
 #ifndef KERNEL
-DeprecatedString Parser::manufacturer_name() const
+ByteString Parser::manufacturer_name() const
 {
     if (!m_legacy_manufacturer_id_valid)
         return "Unknown";
@@ -998,9 +998,9 @@ ErrorOr<IterationDecision> Parser::for_each_display_descriptor(Function<Iteratio
 }
 
 #ifndef KERNEL
-DeprecatedString Parser::display_product_name() const
+ByteString Parser::display_product_name() const
 {
-    DeprecatedString product_name;
+    ByteString product_name;
     auto result = for_each_display_descriptor([&](u8 descriptor_tag, Definitions::DisplayDescriptor const& display_descriptor) {
         if (descriptor_tag != (u8)Definitions::DisplayDescriptorTag::DisplayProductName)
             return IterationDecision::Continue;
@@ -1011,7 +1011,7 @@ DeprecatedString Parser::display_product_name() const
                 break;
             str.append((char)byte);
         }
-        product_name = str.to_deprecated_string();
+        product_name = str.to_byte_string();
         return IterationDecision::Break;
     });
     if (result.is_error()) {
@@ -1021,9 +1021,9 @@ DeprecatedString Parser::display_product_name() const
     return product_name;
 }
 
-DeprecatedString Parser::display_product_serial_number() const
+ByteString Parser::display_product_serial_number() const
 {
-    DeprecatedString product_name;
+    ByteString product_name;
     auto result = for_each_display_descriptor([&](u8 descriptor_tag, Definitions::DisplayDescriptor const& display_descriptor) {
         if (descriptor_tag != (u8)Definitions::DisplayDescriptorTag::DisplayProductSerialNumber)
             return IterationDecision::Continue;
@@ -1034,7 +1034,7 @@ DeprecatedString Parser::display_product_serial_number() const
                 break;
             str.append((char)byte);
         }
-        product_name = str.to_deprecated_string();
+        product_name = str.to_byte_string();
         return IterationDecision::Break;
     });
     if (result.is_error()) {
diff --git a/Userland/Libraries/LibEDID/EDID.h b/Userland/Libraries/LibEDID/EDID.h
index 9f6e1ce8e55..f6bf83d45ea 100644
--- a/Userland/Libraries/LibEDID/EDID.h
+++ b/Userland/Libraries/LibEDID/EDID.h
@@ -22,7 +22,7 @@
 #ifdef KERNEL
 #    include <Kernel/Library/KString.h>
 #else
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace EDID {
@@ -87,12 +87,12 @@ public:
 
 #ifndef KERNEL
     static ErrorOr<Parser> from_display_connector_device(int);
-    static ErrorOr<Parser> from_display_connector_device(DeprecatedString const&);
+    static ErrorOr<Parser> from_display_connector_device(ByteString const&);
 #endif
 
     StringView legacy_manufacturer_id() const;
 #ifndef KERNEL
-    DeprecatedString manufacturer_name() const;
+    ByteString manufacturer_name() const;
 #endif
 
     u16 product_code() const;
@@ -367,8 +367,8 @@ public:
     Optional<DetailedTiming> detailed_timing(size_t) const;
 
 #ifndef KERNEL
-    DeprecatedString display_product_name() const;
-    DeprecatedString display_product_serial_number() const;
+    ByteString display_product_name() const;
+    ByteString display_product_serial_number() const;
 #endif
 
     ErrorOr<IterationDecision> for_each_short_video_descriptor(Function<IterationDecision(unsigned, bool, VIC::Details const&)>) const;
@@ -455,7 +455,7 @@ private:
 #ifdef KERNEL
     OwnPtr<Kernel::KString> m_version;
 #else
-    DeprecatedString m_version;
+    ByteString m_version;
 #endif
     char m_legacy_manufacturer_id[4] {};
     bool m_legacy_manufacturer_id_valid { false };
diff --git a/Userland/Libraries/LibELF/Core.h b/Userland/Libraries/LibELF/Core.h
index 3d1b4f17ef4..ac0ac5962d8 100644
--- a/Userland/Libraries/LibELF/Core.h
+++ b/Userland/Libraries/LibELF/Core.h
@@ -10,7 +10,7 @@
 #include <sys/arch/regs.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace ELF::Core {
@@ -39,9 +39,9 @@ struct [[gnu::packed]] ProcessInfo {
     // Keys:
     // - "pid" (int)
     // - "termination_signal" (u8)
-    // - "executable_path" (DeprecatedString)
-    // - "arguments" (Vector<DeprecatedString>)
-    // - "environment" (Vector<DeprecatedString>)
+    // - "executable_path" (ByteString)
+    // - "arguments" (Vector<ByteString>)
+    // - "environment" (Vector<ByteString>)
     char json_data[]; // Null terminated
 };
 
@@ -59,7 +59,7 @@ struct [[gnu::packed]] MemoryRegionInfo {
     char region_name[]; // Null terminated
 
 #ifndef KERNEL
-    DeprecatedString object_name() const
+    ByteString object_name() const
     {
         StringView memory_region_name { region_name, strlen(region_name) };
         if (memory_region_name.contains("Loader.so"sv))
@@ -67,7 +67,7 @@ struct [[gnu::packed]] MemoryRegionInfo {
         auto maybe_colon_index = memory_region_name.find(':');
         if (!maybe_colon_index.has_value())
             return {};
-        return memory_region_name.substring_view(0, *maybe_colon_index).to_deprecated_string();
+        return memory_region_name.substring_view(0, *maybe_colon_index).to_byte_string();
     }
 #endif
 };
diff --git a/Userland/Libraries/LibELF/DynamicLinker.cpp b/Userland/Libraries/LibELF/DynamicLinker.cpp
index 46ee7aebba7..e00f1fe3cb0 100644
--- a/Userland/Libraries/LibELF/DynamicLinker.cpp
+++ b/Userland/Libraries/LibELF/DynamicLinker.cpp
@@ -36,12 +36,12 @@
 
 namespace ELF {
 
-static HashMap<DeprecatedString, NonnullRefPtr<ELF::DynamicLoader>> s_loaders;
-static DeprecatedString s_main_program_path;
+static HashMap<ByteString, NonnullRefPtr<ELF::DynamicLoader>> s_loaders;
+static ByteString s_main_program_path;
 
 // Dependencies have to always be added after the object that depends on them in `s_global_objects`.
 // This is needed for calling the destructors in the correct order.
-static OrderedHashMap<DeprecatedString, NonnullRefPtr<ELF::DynamicObject>> s_global_objects;
+static OrderedHashMap<ByteString, NonnullRefPtr<ELF::DynamicObject>> s_global_objects;
 
 using EntryPointFunction = int (*)(int, char**, char**);
 using LibCExitFunction = void (*)(int);
@@ -57,13 +57,13 @@ static size_t s_allocated_tls_block_size = 0;
 static char** s_envp = nullptr;
 static LibCExitFunction s_libc_exit = nullptr;
 static __pthread_mutex_t s_loader_lock = __PTHREAD_MUTEX_INITIALIZER;
-static DeprecatedString s_cwd;
+static ByteString s_cwd;
 
 static bool s_allowed_to_check_environment_variables { false };
 static bool s_do_breakpoint_trap_before_entry { false };
 static StringView s_ld_library_path;
 static StringView s_main_program_pledge_promises;
-static DeprecatedString s_loader_pledge_promises;
+static ByteString s_loader_pledge_promises;
 
 static Result<void, DlErrorMessage> __dlclose(void* handle);
 static Result<void*, DlErrorMessage> __dlopen(char const* filename, int flags);
@@ -90,7 +90,7 @@ Optional<DynamicObject::SymbolLookupResult> DynamicLinker::lookup_global_symbol(
     return weak_result;
 }
 
-static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> map_library(DeprecatedString const& filepath, int fd)
+static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> map_library(ByteString const& filepath, int fd)
 {
     VERIFY(filepath.starts_with('/'));
 
@@ -110,7 +110,7 @@ static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> map_library(Deprecat
     return loader;
 }
 
-Optional<DeprecatedString> DynamicLinker::resolve_library(DeprecatedString const& name, DynamicObject const& parent_object)
+Optional<ByteString> DynamicLinker::resolve_library(ByteString const& name, DynamicObject const& parent_object)
 {
     // Absolute and relative (to the current working directory) paths are already considered resolved.
     // However, ensure that the returned path is absolute and canonical, so pass it through LexicalPath.
@@ -135,7 +135,7 @@ Optional<DeprecatedString> DynamicLinker::resolve_library(DeprecatedString const
 
     for (auto const& search_path : search_paths) {
         LexicalPath library_path(search_path.replace("$ORIGIN"sv, LexicalPath::dirname(parent_object.filepath()), ReplaceMode::FirstOnly));
-        DeprecatedString library_name = library_path.append(name).string();
+        ByteString library_name = library_path.append(name).string();
 
         if (access(library_name.characters(), F_OK) == 0) {
             if (!library_name.starts_with('/')) {
@@ -152,24 +152,24 @@ Optional<DeprecatedString> DynamicLinker::resolve_library(DeprecatedString const
     return {};
 }
 
-static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> map_library(DeprecatedString const& path)
+static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> map_library(ByteString const& path)
 {
     VERIFY(path.starts_with('/'));
 
     int fd = open(path.characters(), O_RDONLY);
     if (fd < 0)
-        return DlErrorMessage { DeprecatedString::formatted("Could not open shared library '{}': {}", path, strerror(errno)) };
+        return DlErrorMessage { ByteString::formatted("Could not open shared library '{}': {}", path, strerror(errno)) };
 
     return map_library(path, fd);
 }
 
-static Vector<DeprecatedString> get_dependencies(DeprecatedString const& path)
+static Vector<ByteString> get_dependencies(ByteString const& path)
 {
     VERIFY(path.starts_with('/'));
 
     auto name = LexicalPath::basename(path);
     auto lib = s_loaders.get(path).value();
-    Vector<DeprecatedString> dependencies;
+    Vector<ByteString> dependencies;
 
     lib->for_each_needed_library([&dependencies, &name](auto needed_name) {
         if (name == needed_name)
@@ -179,7 +179,7 @@ static Vector<DeprecatedString> get_dependencies(DeprecatedString const& path)
     return dependencies;
 }
 
-static Result<void, DlErrorMessage> map_dependencies(DeprecatedString const& path)
+static Result<void, DlErrorMessage> map_dependencies(ByteString const& path)
 {
     VERIFY(path.starts_with('/'));
 
@@ -193,7 +193,7 @@ static Result<void, DlErrorMessage> map_dependencies(DeprecatedString const& pat
         auto dependency_path = DynamicLinker::resolve_library(needed_name, parent_object);
 
         if (!dependency_path.has_value())
-            return DlErrorMessage { DeprecatedString::formatted("Could not find required shared library: {}", needed_name) };
+            return DlErrorMessage { ByteString::formatted("Could not find required shared library: {}", needed_name) };
 
         if (!s_loaders.contains(dependency_path.value()) && !s_global_objects.contains(dependency_path.value())) {
             auto loader = TRY(map_library(dependency_path.value()));
@@ -321,7 +321,7 @@ static void initialize_libc(DynamicObject& libc)
 }
 
 template<typename Callback>
-static void for_each_unfinished_dependency_of(DeprecatedString const& path, HashTable<DeprecatedString>& seen_names, Callback callback)
+static void for_each_unfinished_dependency_of(ByteString const& path, HashTable<ByteString>& seen_names, Callback callback)
 {
     VERIFY(path.starts_with('/'));
 
@@ -356,11 +356,11 @@ static void for_each_unfinished_dependency_of(DeprecatedString const& path, Hash
     callback(*s_loaders.get(path).value());
 }
 
-static Vector<NonnullRefPtr<DynamicLoader>> collect_loaders_for_library(DeprecatedString const& path)
+static Vector<NonnullRefPtr<DynamicLoader>> collect_loaders_for_library(ByteString const& path)
 {
     VERIFY(path.starts_with('/'));
 
-    HashTable<DeprecatedString> seen_names;
+    HashTable<ByteString> seen_names;
     Vector<NonnullRefPtr<DynamicLoader>> loaders;
     for_each_unfinished_dependency_of(path, seen_names, [&](auto& loader) {
         loaders.append(loader);
@@ -375,7 +375,7 @@ static void drop_loader_promise(StringView promise_to_drop)
 
     s_loader_pledge_promises = s_loader_pledge_promises.replace(promise_to_drop, ""sv, ReplaceMode::All);
 
-    auto extended_promises = DeprecatedString::formatted("{} {}", s_main_program_pledge_promises, s_loader_pledge_promises);
+    auto extended_promises = ByteString::formatted("{} {}", s_main_program_pledge_promises, s_loader_pledge_promises);
     Syscall::SC_pledge_params params {
         { extended_promises.characters(), extended_promises.length() },
         { nullptr, 0 },
@@ -387,7 +387,7 @@ static void drop_loader_promise(StringView promise_to_drop)
     }
 }
 
-static Result<void, DlErrorMessage> link_main_library(DeprecatedString const& path, int flags)
+static Result<void, DlErrorMessage> link_main_library(ByteString const& path, int flags)
 {
     VERIFY(path.starts_with('/'));
 
@@ -400,7 +400,7 @@ static Result<void, DlErrorMessage> link_main_library(DeprecatedString const& pa
     for (auto& loader : loaders) {
         bool success = loader->link(flags);
         if (!success) {
-            return DlErrorMessage { DeprecatedString::formatted("Failed to link library {}", loader->filepath()) };
+            return DlErrorMessage { ByteString::formatted("Failed to link library {}", loader->filepath()) };
         }
     }
 
@@ -503,7 +503,7 @@ static Result<void*, DlErrorMessage> __dlopen(char const* filename, int flags)
     auto library_path = (filename ? DynamicLinker::resolve_library(filename, parent_object) : s_main_program_path);
 
     if (!library_path.has_value())
-        return DlErrorMessage { DeprecatedString::formatted("Could not find required shared library: {}", filename) };
+        return DlErrorMessage { ByteString::formatted("Could not find required shared library: {}", filename) };
 
     auto existing_elf_object = s_global_objects.get(library_path.value());
     if (existing_elf_object.has_value()) {
@@ -552,7 +552,7 @@ static Result<void*, DlErrorMessage> __dlsym(void* handle, char const* symbol_na
     }
 
     if (!symbol.has_value())
-        return DlErrorMessage { DeprecatedString::formatted("Symbol {} not found", symbol_name_view) };
+        return DlErrorMessage { ByteString::formatted("Symbol {} not found", symbol_name_view) };
 
     if (symbol.value().type == STT_GNU_IFUNC)
         return (void*)reinterpret_cast<DynamicObject::IfuncResolver>(symbol.value().address.as_ptr())();
@@ -656,7 +656,7 @@ static void read_environment_variables()
     }
 }
 
-void ELF::DynamicLinker::linker_main(DeprecatedString&& main_program_path, int main_program_fd, bool is_secure, int argc, char** argv, char** envp)
+void ELF::DynamicLinker::linker_main(ByteString&& main_program_path, int main_program_fd, bool is_secure, int argc, char** argv, char** envp)
 {
     VERIFY(main_program_path.starts_with('/'));
 
diff --git a/Userland/Libraries/LibELF/DynamicLinker.h b/Userland/Libraries/LibELF/DynamicLinker.h
index 4cfa7a6419d..9dbdeb9a759 100644
--- a/Userland/Libraries/LibELF/DynamicLinker.h
+++ b/Userland/Libraries/LibELF/DynamicLinker.h
@@ -15,9 +15,9 @@ namespace ELF {
 class DynamicLinker {
 public:
     static Optional<DynamicObject::SymbolLookupResult> lookup_global_symbol(StringView symbol);
-    [[noreturn]] static void linker_main(DeprecatedString&& main_program_path, int fd, bool is_secure, int argc, char** argv, char** envp);
+    [[noreturn]] static void linker_main(ByteString&& main_program_path, int fd, bool is_secure, int argc, char** argv, char** envp);
 
-    static Optional<DeprecatedString> resolve_library(DeprecatedString const& name, DynamicObject const& parent_object);
+    static Optional<ByteString> resolve_library(ByteString const& name, DynamicObject const& parent_object);
 
 private:
     DynamicLinker() = delete;
diff --git a/Userland/Libraries/LibELF/DynamicLoader.cpp b/Userland/Libraries/LibELF/DynamicLoader.cpp
index bddae314d0f..6220989c426 100644
--- a/Userland/Libraries/LibELF/DynamicLoader.cpp
+++ b/Userland/Libraries/LibELF/DynamicLoader.cpp
@@ -44,7 +44,7 @@ void* __tlsdesc_static(void*);
 
 namespace ELF {
 
-Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> DynamicLoader::try_create(int fd, DeprecatedString filepath)
+Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> DynamicLoader::try_create(int fd, ByteString filepath)
 {
     VERIFY(filepath.starts_with('/'));
 
@@ -56,9 +56,9 @@ Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> DynamicLoader::try_create(i
     VERIFY(stat.st_size >= 0);
     auto size = static_cast<size_t>(stat.st_size);
     if (size < sizeof(Elf_Ehdr))
-        return DlErrorMessage { DeprecatedString::formatted("File {} has invalid ELF header", filepath) };
+        return DlErrorMessage { ByteString::formatted("File {} has invalid ELF header", filepath) };
 
-    DeprecatedString file_mmap_name = DeprecatedString::formatted("ELF_DYN: {}", filepath);
+    ByteString file_mmap_name = ByteString::formatted("ELF_DYN: {}", filepath);
     auto* data = mmap_with_name(nullptr, size, PROT_READ, MAP_SHARED, fd, 0, file_mmap_name.characters());
     if (data == MAP_FAILED) {
         return DlErrorMessage { "DynamicLoader::try_create mmap" };
@@ -70,7 +70,7 @@ Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> DynamicLoader::try_create(i
     return loader;
 }
 
-DynamicLoader::DynamicLoader(int fd, DeprecatedString filepath, void* data, size_t size)
+DynamicLoader::DynamicLoader(int fd, ByteString filepath, void* data, size_t size)
     : m_filepath(move(filepath))
     , m_file_size(size)
     , m_image_fd(fd)
@@ -293,19 +293,19 @@ Result<NonnullRefPtr<DynamicObject>, DlErrorMessage> DynamicLoader::load_stage_3
         // If we don't have textrels, .text has already been made executable by this point in load_stage_2.
         for (auto& text_segment : m_text_segments) {
             if (mprotect(text_segment.address().as_ptr(), text_segment.size(), PROT_READ | PROT_EXEC) < 0) {
-                return DlErrorMessage { DeprecatedString::formatted("mprotect .text: PROT_READ | PROT_EXEC: {}", strerror(errno)) };
+                return DlErrorMessage { ByteString::formatted("mprotect .text: PROT_READ | PROT_EXEC: {}", strerror(errno)) };
             }
         }
     }
 
     if (m_relro_segment_size) {
         if (mprotect(m_relro_segment_address.as_ptr(), m_relro_segment_size, PROT_READ) < 0) {
-            return DlErrorMessage { DeprecatedString::formatted("mprotect .relro: PROT_READ: {}", strerror(errno)) };
+            return DlErrorMessage { ByteString::formatted("mprotect .relro: PROT_READ: {}", strerror(errno)) };
         }
 
 #ifdef AK_OS_SERENITY
-        if (set_mmap_name(m_relro_segment_address.as_ptr(), m_relro_segment_size, DeprecatedString::formatted("{}: .relro", m_filepath).characters()) < 0) {
-            return DlErrorMessage { DeprecatedString::formatted("set_mmap_name .relro: {}", strerror(errno)) };
+        if (set_mmap_name(m_relro_segment_address.as_ptr(), m_relro_segment_size, ByteString::formatted("{}: .relro", m_filepath).characters()) < 0) {
+            return DlErrorMessage { ByteString::formatted("set_mmap_name .relro: {}", strerror(errno)) };
         }
 #endif
     }
@@ -388,7 +388,7 @@ void DynamicLoader::load_program_headers()
     }
 
     // Now that we can't accidentally block our requested space, re-map our ELF image.
-    DeprecatedString file_mmap_name = DeprecatedString::formatted("ELF_DYN: {}", m_filepath);
+    ByteString file_mmap_name = ByteString::formatted("ELF_DYN: {}", m_filepath);
     auto* data = mmap_with_name(nullptr, m_file_size, PROT_READ, MAP_SHARED, m_image_fd, 0, file_mmap_name.characters());
     if (data == MAP_FAILED) {
         perror("mmap new mapping");
@@ -444,9 +444,9 @@ void DynamicLoader::load_program_headers()
 
     // Pre-allocate any malloc memory needed before unmapping the reservation.
     // We don't want any future malloc to accidentally mmap a reserved address!
-    DeprecatedString text_segment_name = DeprecatedString::formatted("{}: .text", m_filepath);
-    DeprecatedString rodata_segment_name = DeprecatedString::formatted("{}: .rodata", m_filepath);
-    DeprecatedString data_segment_name = DeprecatedString::formatted("{}: .data", m_filepath);
+    ByteString text_segment_name = ByteString::formatted("{}: .text", m_filepath);
+    ByteString rodata_segment_name = ByteString::formatted("{}: .rodata", m_filepath);
+    ByteString data_segment_name = ByteString::formatted("{}: .data", m_filepath);
 
     m_text_segments.ensure_capacity(map_regions.size());
 
diff --git a/Userland/Libraries/LibELF/DynamicLoader.h b/Userland/Libraries/LibELF/DynamicLoader.h
index cc00ac1d204..14ad59865d9 100644
--- a/Userland/Libraries/LibELF/DynamicLoader.h
+++ b/Userland/Libraries/LibELF/DynamicLoader.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/OwnPtr.h>
 #include <AK/RefCounted.h>
 #include <LibELF/DynamicObject.h>
@@ -49,10 +49,10 @@ extern "C" FlatPtr _fixup_plt_entry(DynamicObject* object, u32 relocation_offset
 
 class DynamicLoader : public RefCounted<DynamicLoader> {
 public:
-    static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> try_create(int fd, DeprecatedString filepath);
+    static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> try_create(int fd, ByteString filepath);
     ~DynamicLoader();
 
-    DeprecatedString const& filepath() const { return m_filepath; }
+    ByteString const& filepath() const { return m_filepath; }
 
     bool is_valid() const { return m_valid; }
 
@@ -94,7 +94,7 @@ public:
     bool is_fully_initialized() const { return m_fully_initialized; }
 
 private:
-    DynamicLoader(int fd, DeprecatedString filepath, void* file_data, size_t file_size);
+    DynamicLoader(int fd, ByteString filepath, void* file_data, size_t file_size);
 
     class ProgramHeaderRegion {
     public:
@@ -153,7 +153,7 @@ private:
     void do_relr_relocations();
     void find_tls_size_and_alignment();
 
-    DeprecatedString m_filepath;
+    ByteString m_filepath;
     size_t m_file_size { 0 };
     int m_image_fd { -1 };
     void* m_file_data { nullptr };
diff --git a/Userland/Libraries/LibELF/DynamicObject.cpp b/Userland/Libraries/LibELF/DynamicObject.cpp
index 082710f8e64..f68e65144f4 100644
--- a/Userland/Libraries/LibELF/DynamicObject.cpp
+++ b/Userland/Libraries/LibELF/DynamicObject.cpp
@@ -5,8 +5,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/StringBuilder.h>
 #include <LibELF/DynamicLoader.h>
 #include <LibELF/DynamicObject.h>
@@ -16,7 +16,7 @@
 
 namespace ELF {
 
-DynamicObject::DynamicObject(DeprecatedString const& filepath, VirtualAddress base_address, VirtualAddress dynamic_section_address)
+DynamicObject::DynamicObject(ByteString const& filepath, VirtualAddress base_address, VirtualAddress dynamic_section_address)
     : m_filepath(filepath)
     , m_base_address(base_address)
     , m_dynamic_address(dynamic_section_address)
@@ -58,7 +58,7 @@ void DynamicObject::dump() const
         size_t num_dynamic_sections = 0;
 
         for_each_dynamic_entry([&](DynamicObject::DynamicEntry const& entry) {
-            DeprecatedString name_field = DeprecatedString::formatted("({})", name_for_dtag(entry.tag()));
+            ByteString name_field = ByteString::formatted("({})", name_for_dtag(entry.tag()));
             builder.appendff("{:#08x} {:17} {:#08x}\n", entry.tag(), name_field, entry.val());
             num_dynamic_sections++;
         });
@@ -508,7 +508,7 @@ auto DynamicObject::lookup_symbol(HashSymbol const& symbol) const -> Optional<Sy
     return SymbolLookupResult { symbol_result.value(), symbol_result.size(), symbol_result.address(), symbol_result.bind(), symbol_result.type(), this };
 }
 
-NonnullRefPtr<DynamicObject> DynamicObject::create(DeprecatedString const& filepath, VirtualAddress base_address, VirtualAddress dynamic_section_address)
+NonnullRefPtr<DynamicObject> DynamicObject::create(ByteString const& filepath, VirtualAddress base_address, VirtualAddress dynamic_section_address)
 {
     return adopt_ref(*new DynamicObject(filepath, base_address, dynamic_section_address));
 }
diff --git a/Userland/Libraries/LibELF/DynamicObject.h b/Userland/Libraries/LibELF/DynamicObject.h
index 2a08fec5fa5..8d10edc955e 100644
--- a/Userland/Libraries/LibELF/DynamicObject.h
+++ b/Userland/Libraries/LibELF/DynamicObject.h
@@ -9,8 +9,8 @@
 #pragma once
 
 #include <AK/Assertions.h>
+#include <AK/ByteString.h>
 #include <AK/Concepts.h>
-#include <AK/DeprecatedString.h>
 #include <AK/RefCounted.h>
 #include <Kernel/Memory/VirtualAddress.h>
 #include <LibELF/ELFABI.h>
@@ -20,7 +20,7 @@ namespace ELF {
 
 class DynamicObject : public RefCounted<DynamicObject> {
 public:
-    static NonnullRefPtr<DynamicObject> create(DeprecatedString const& filepath, VirtualAddress base_address, VirtualAddress dynamic_section_address);
+    static NonnullRefPtr<DynamicObject> create(ByteString const& filepath, VirtualAddress base_address, VirtualAddress dynamic_section_address);
     static char const* name_for_dtag(Elf_Sword d_tag);
 
     ~DynamicObject();
@@ -284,7 +284,7 @@ public:
     VirtualAddress plt_got_base_address() const { return m_base_address.offset(m_procedure_linkage_table_offset.value()); }
     VirtualAddress base_address() const { return m_base_address; }
 
-    DeprecatedString const& filepath() const { return m_filepath; }
+    ByteString const& filepath() const { return m_filepath; }
 
     StringView rpath() const { return m_has_rpath ? symbol_string_table_string(m_rpath_index) : StringView {}; }
     StringView runpath() const { return m_has_runpath ? symbol_string_table_string(m_runpath_index) : StringView {}; }
@@ -332,13 +332,13 @@ public:
     void* symbol_for_name(StringView name);
 
 private:
-    explicit DynamicObject(DeprecatedString const& filepath, VirtualAddress base_address, VirtualAddress dynamic_section_address);
+    explicit DynamicObject(ByteString const& filepath, VirtualAddress base_address, VirtualAddress dynamic_section_address);
 
     StringView symbol_string_table_string(Elf_Word) const;
     char const* raw_symbol_string_table_string(Elf_Word) const;
     void parse();
 
-    DeprecatedString m_filepath;
+    ByteString m_filepath;
 
     VirtualAddress m_base_address;
     VirtualAddress m_dynamic_address;
diff --git a/Userland/Libraries/LibELF/Image.cpp b/Userland/Libraries/LibELF/Image.cpp
index 6b662949140..98c31705087 100644
--- a/Userland/Libraries/LibELF/Image.cpp
+++ b/Userland/Libraries/LibELF/Image.cpp
@@ -438,7 +438,7 @@ NEVER_INLINE void Image::sort_symbols() const
     });
 }
 
-DeprecatedString Image::symbolicate(FlatPtr address, u32* out_offset) const
+ByteString Image::symbolicate(FlatPtr address, u32* out_offset) const
 {
     auto symbol_count = this->symbol_count();
     if (!symbol_count) {
@@ -462,7 +462,7 @@ DeprecatedString Image::symbolicate(FlatPtr address, u32* out_offset) const
         *out_offset = address - symbol->address;
         return demangled_name;
     }
-    return DeprecatedString::formatted("{} +{:#x}", demangled_name, address - symbol->address);
+    return ByteString::formatted("{} +{:#x}", demangled_name, address - symbol->address);
 }
 #endif
 
diff --git a/Userland/Libraries/LibELF/Image.h b/Userland/Libraries/LibELF/Image.h
index 4ca5244b763..fcd3c5248c4 100644
--- a/Userland/Libraries/LibELF/Image.h
+++ b/Userland/Libraries/LibELF/Image.h
@@ -13,7 +13,7 @@
 #include <LibELF/ELFABI.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace ELF {
@@ -221,7 +221,7 @@ public:
     bool has_symbols() const { return symbol_count(); }
 #ifndef KERNEL
     Optional<Symbol> find_demangled_function(StringView name) const;
-    DeprecatedString symbolicate(FlatPtr address, u32* offset = nullptr) const;
+    ByteString symbolicate(FlatPtr address, u32* offset = nullptr) const;
 #endif
     Optional<Image::Symbol> find_symbol(FlatPtr address, u32* offset = nullptr) const;
 
@@ -246,7 +246,7 @@ private:
     struct SortedSymbol {
         FlatPtr address;
         StringView name;
-        DeprecatedString demangled_name;
+        ByteString demangled_name;
         Optional<Image::Symbol> symbol;
     };
 
diff --git a/Userland/Libraries/LibFileSystem/FileSystem.cpp b/Userland/Libraries/LibFileSystem/FileSystem.cpp
index e63ff317cb1..cbae433f043 100644
--- a/Userland/Libraries/LibFileSystem/FileSystem.cpp
+++ b/Userland/Libraries/LibFileSystem/FileSystem.cpp
@@ -26,7 +26,7 @@ namespace FileSystem {
 ErrorOr<String> current_working_directory()
 {
     auto cwd = TRY(Core::System::getcwd());
-    return TRY(String::from_deprecated_string({ cwd }));
+    return TRY(String::from_byte_string({ cwd }));
 }
 
 ErrorOr<String> absolute_path(StringView path)
@@ -35,12 +35,12 @@ ErrorOr<String> absolute_path(StringView path)
         return TRY(real_path(path));
 
     if (path.starts_with("/"sv))
-        return TRY(String::from_deprecated_string(LexicalPath::canonicalized_path(path)));
+        return TRY(String::from_byte_string(LexicalPath::canonicalized_path(path)));
 
     auto working_directory = TRY(current_working_directory());
     auto full_path = LexicalPath::join(working_directory, path).string();
 
-    return TRY(String::from_deprecated_string(LexicalPath::canonicalized_path(full_path)));
+    return TRY(String::from_byte_string(LexicalPath::canonicalized_path(full_path)));
 }
 
 ErrorOr<String> real_path(StringView path)
@@ -48,7 +48,7 @@ ErrorOr<String> real_path(StringView path)
     if (path.is_null())
         return Error::from_errno(ENOENT);
 
-    DeprecatedString dep_path = path;
+    ByteString dep_path = path;
     char* real_path = realpath(dep_path.characters(), nullptr);
     ScopeGuard free_path = [real_path]() { free(real_path); };
 
@@ -182,11 +182,11 @@ static ErrorOr<String> get_duplicate_file_name(StringView path)
     LexicalPath lexical_path(path);
     auto parent_path = LexicalPath::canonicalized_path(lexical_path.dirname());
     auto basename = lexical_path.basename();
-    auto current_name = TRY(String::from_deprecated_string(LexicalPath::join(parent_path, basename).string()));
+    auto current_name = TRY(String::from_byte_string(LexicalPath::join(parent_path, basename).string()));
 
     while (exists(current_name)) {
         ++duplicate_count;
-        current_name = TRY(String::from_deprecated_string(LexicalPath::join(parent_path, TRY(String::formatted("{} ({})", basename, duplicate_count))).string()));
+        current_name = TRY(String::from_byte_string(LexicalPath::join(parent_path, TRY(String::formatted("{} ({})", basename, duplicate_count))).string()));
     }
 
     return current_name;
@@ -260,7 +260,7 @@ ErrorOr<void> copy_directory(StringView destination_path, StringView source_path
         return di.error();
 
     while (di.has_next()) {
-        auto filename = TRY(String::from_deprecated_string(di.next_path()));
+        auto filename = TRY(String::from_byte_string(di.next_path()));
         TRY(copy_file_or_directory(
             TRY(String::formatted("{}/{}", destination_path, filename)),
             TRY(String::formatted("{}/{}", source_path, filename)),
@@ -388,7 +388,7 @@ bool can_delete_or_move(StringView path)
 
 ErrorOr<String> read_link(StringView link_path)
 {
-    return TRY(String::from_deprecated_string(TRY(Core::System::readlink(link_path))));
+    return TRY(String::from_byte_string(TRY(Core::System::readlink(link_path))));
 }
 
 ErrorOr<void> link_file(StringView destination_path, StringView source_path)
diff --git a/Userland/Libraries/LibFileSystemAccessClient/Client.cpp b/Userland/Libraries/LibFileSystemAccessClient/Client.cpp
index d6a6ec9d9f1..00634058905 100644
--- a/Userland/Libraries/LibFileSystemAccessClient/Client.cpp
+++ b/Userland/Libraries/LibFileSystemAccessClient/Client.cpp
@@ -23,7 +23,7 @@ Client& Client::the()
     return *s_the;
 }
 
-Result Client::request_file_read_only_approved(GUI::Window* parent_window, DeprecatedString const& path)
+Result Client::request_file_read_only_approved(GUI::Window* parent_window, ByteString const& path)
 {
     auto const id = get_new_id();
     m_promises.set(id, RequestData { { Core::Promise<Result>::construct() }, parent_window, Core::File::OpenMode::Read });
@@ -38,7 +38,7 @@ Result Client::request_file_read_only_approved(GUI::Window* parent_window, Depre
     return handle_promise(id);
 }
 
-Result Client::request_file(GUI::Window* parent_window, DeprecatedString const& path, Core::File::OpenMode mode)
+Result Client::request_file(GUI::Window* parent_window, ByteString const& path, Core::File::OpenMode mode)
 {
     auto const id = get_new_id();
     m_promises.set(id, RequestData { { Core::Promise<Result>::construct() }, parent_window, mode });
@@ -83,7 +83,7 @@ Result Client::open_file(GUI::Window* parent_window, OpenFileOptions const& opti
     return handle_promise(id);
 }
 
-Result Client::save_file(GUI::Window* parent_window, DeprecatedString const& name, DeprecatedString const ext, Core::File::OpenMode requested_access)
+Result Client::save_file(GUI::Window* parent_window, ByteString const& name, ByteString const ext, Core::File::OpenMode requested_access)
 {
     auto const id = get_new_id();
     m_promises.set(id, RequestData { { Core::Promise<Result>::construct() }, parent_window, requested_access });
@@ -103,7 +103,7 @@ Result Client::save_file(GUI::Window* parent_window, DeprecatedString const& nam
     return handle_promise(id);
 }
 
-void Client::handle_prompt_end(i32 request_id, i32 error, Optional<IPC::File> const& ipc_file, Optional<DeprecatedString> const& chosen_file)
+void Client::handle_prompt_end(i32 request_id, i32 error, Optional<IPC::File> const& ipc_file, Optional<ByteString> const& chosen_file)
 {
     auto potential_data = m_promises.get(request_id);
     VERIFY(potential_data.has_value());
@@ -145,7 +145,7 @@ void Client::handle_prompt_end(i32 request_id, i32 error, Optional<IPC::File> co
 
     auto file_or_error = [&]() -> ErrorOr<File> {
         auto stream = TRY(Core::File::adopt_fd(ipc_file->take_fd(), Core::File::OpenMode::ReadWrite));
-        auto filename = TRY(String::from_deprecated_string(*chosen_file));
+        auto filename = TRY(String::from_byte_string(*chosen_file));
         return File({}, move(stream), filename);
     }();
     if (file_or_error.is_error()) {
diff --git a/Userland/Libraries/LibFileSystemAccessClient/Client.h b/Userland/Libraries/LibFileSystemAccessClient/Client.h
index caf769f4db0..d2044c5f7f2 100644
--- a/Userland/Libraries/LibFileSystemAccessClient/Client.h
+++ b/Userland/Libraries/LibFileSystemAccessClient/Client.h
@@ -50,7 +50,7 @@ using Result = ErrorOr<File>;
 
 struct OpenFileOptions {
     StringView window_title = {};
-    DeprecatedString path = Core::StandardPaths::home_directory();
+    ByteString path = Core::StandardPaths::home_directory();
     Core::File::OpenMode requested_access = Core::File::OpenMode::Read;
     Optional<Vector<GUI::FileTypeFilter>> allowed_file_types = {};
 };
@@ -61,10 +61,10 @@ class Client final
     IPC_CLIENT_CONNECTION(Client, "/tmp/session/%sid/portal/filesystemaccess"sv)
 
 public:
-    Result request_file_read_only_approved(GUI::Window* parent_window, DeprecatedString const& path);
-    Result request_file(GUI::Window* parent_window, DeprecatedString const& path, Core::File::OpenMode requested_access);
+    Result request_file_read_only_approved(GUI::Window* parent_window, ByteString const& path);
+    Result request_file(GUI::Window* parent_window, ByteString const& path, Core::File::OpenMode requested_access);
     Result open_file(GUI::Window* parent_window, OpenFileOptions const& = {});
-    Result save_file(GUI::Window* parent_window, DeprecatedString const& name, DeprecatedString const ext, Core::File::OpenMode requested_access = Core::File::OpenMode::Write | Core::File::OpenMode::Truncate);
+    Result save_file(GUI::Window* parent_window, ByteString const& name, ByteString const ext, Core::File::OpenMode requested_access = Core::File::OpenMode::Write | Core::File::OpenMode::Truncate);
 
     void set_silence_errors(u32 flags) { m_silenced_errors = flags; }
     u32 silenced_errors() const { return m_silenced_errors; }
@@ -84,7 +84,7 @@ private:
     {
     }
 
-    virtual void handle_prompt_end(i32 request_id, i32 error, Optional<IPC::File> const& fd, Optional<DeprecatedString> const& chosen_file) override;
+    virtual void handle_prompt_end(i32 request_id, i32 error, Optional<IPC::File> const& fd, Optional<ByteString> const& chosen_file) override;
 
     int get_new_id();
     Result handle_promise(int);
diff --git a/Userland/Libraries/LibGPU/DeviceInfo.h b/Userland/Libraries/LibGPU/DeviceInfo.h
index b9f11c472d7..c5d23ce6a63 100644
--- a/Userland/Libraries/LibGPU/DeviceInfo.h
+++ b/Userland/Libraries/LibGPU/DeviceInfo.h
@@ -6,13 +6,13 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 
 namespace GPU {
 
 struct DeviceInfo final {
-    DeprecatedString vendor_name;
-    DeprecatedString device_name;
+    ByteString vendor_name;
+    ByteString device_name;
     unsigned num_texture_units;
     unsigned num_lights;
     unsigned max_clip_planes;
diff --git a/Userland/Libraries/LibGPU/Driver.cpp b/Userland/Libraries/LibGPU/Driver.cpp
index 4da642f6277..74b9bfec3de 100644
--- a/Userland/Libraries/LibGPU/Driver.cpp
+++ b/Userland/Libraries/LibGPU/Driver.cpp
@@ -27,7 +27,7 @@ static HashMap<StringView, char const*> const s_driver_path_map
 };
 // clang-format on
 
-static HashMap<DeprecatedString, WeakPtr<Driver>> s_loaded_drivers;
+static HashMap<ByteString, WeakPtr<Driver>> s_loaded_drivers;
 
 ErrorOr<NonnullRefPtr<Driver>> Driver::try_create(StringView driver_name)
 {
diff --git a/Userland/Libraries/LibGUI/AboutDialog.cpp b/Userland/Libraries/LibGUI/AboutDialog.cpp
index de64deca1d1..fed6a9d0af3 100644
--- a/Userland/Libraries/LibGUI/AboutDialog.cpp
+++ b/Userland/Libraries/LibGUI/AboutDialog.cpp
@@ -22,7 +22,7 @@ namespace GUI {
 NonnullRefPtr<AboutDialog> AboutDialog::create(String const& name, String version, RefPtr<Gfx::Bitmap const> icon, Window* parent_window)
 {
     auto dialog = adopt_ref(*new AboutDialog(name, version, icon, parent_window));
-    dialog->set_title(DeprecatedString::formatted("About {}", name));
+    dialog->set_title(ByteString::formatted("About {}", name));
 
     auto widget = dialog->set_main_widget<Widget>();
     MUST(widget->load_from_gml(about_dialog_gml));
diff --git a/Userland/Libraries/LibGUI/AbstractTableView.cpp b/Userland/Libraries/LibGUI/AbstractTableView.cpp
index 180295c1b53..071cca279fe 100644
--- a/Userland/Libraries/LibGUI/AbstractTableView.cpp
+++ b/Userland/Libraries/LibGUI/AbstractTableView.cpp
@@ -73,7 +73,7 @@ void AbstractTableView::auto_resize_column(int column)
         } else if (cell_data.is_bitmap()) {
             cell_width = cell_data.as_bitmap().width();
         } else if (cell_data.is_valid()) {
-            cell_width = font().width(cell_data.to_deprecated_string());
+            cell_width = font().width(cell_data.to_byte_string());
         }
         if (is_empty && cell_width > 0)
             is_empty = false;
@@ -111,7 +111,7 @@ void AbstractTableView::update_column_sizes()
             } else if (cell_data.is_bitmap()) {
                 cell_width = cell_data.as_bitmap().width();
             } else if (cell_data.is_valid()) {
-                cell_width = font().width(cell_data.to_deprecated_string());
+                cell_width = font().width(cell_data.to_byte_string());
             }
             column_width = max(column_width, cell_width);
         }
diff --git a/Userland/Libraries/LibGUI/AbstractThemePreview.cpp b/Userland/Libraries/LibGUI/AbstractThemePreview.cpp
index 9f43533d11f..5b2a9fb28d9 100644
--- a/Userland/Libraries/LibGUI/AbstractThemePreview.cpp
+++ b/Userland/Libraries/LibGUI/AbstractThemePreview.cpp
@@ -38,14 +38,14 @@ AbstractThemePreview::AbstractThemePreview(Gfx::Palette const& preview_palette)
 
 void AbstractThemePreview::load_theme_bitmaps()
 {
-    auto load_bitmap = [](DeprecatedString const& path, DeprecatedString& last_path, RefPtr<Gfx::Bitmap>& bitmap) {
+    auto load_bitmap = [](ByteString const& path, ByteString& last_path, RefPtr<Gfx::Bitmap>& bitmap) {
         if (path.is_empty()) {
-            last_path = DeprecatedString::empty();
+            last_path = ByteString::empty();
             bitmap = nullptr;
         } else if (last_path != path) {
             auto bitmap_or_error = Gfx::Bitmap::load_from_file(path);
             if (bitmap_or_error.is_error()) {
-                last_path = DeprecatedString::empty();
+                last_path = ByteString::empty();
                 bitmap = nullptr;
             } else {
                 last_path = path;
diff --git a/Userland/Libraries/LibGUI/AbstractThemePreview.h b/Userland/Libraries/LibGUI/AbstractThemePreview.h
index a73300b2383..d9249eea03f 100644
--- a/Userland/Libraries/LibGUI/AbstractThemePreview.h
+++ b/Userland/Libraries/LibGUI/AbstractThemePreview.h
@@ -70,20 +70,20 @@ private:
     RefPtr<Gfx::Bitmap> m_close_bitmap;
     RefPtr<Gfx::Bitmap> m_maximize_bitmap;
     RefPtr<Gfx::Bitmap> m_minimize_bitmap;
-    DeprecatedString m_last_close_path;
-    DeprecatedString m_last_maximize_path;
-    DeprecatedString m_last_minimize_path;
+    ByteString m_last_close_path;
+    ByteString m_last_maximize_path;
+    ByteString m_last_minimize_path;
 
     RefPtr<Gfx::Bitmap> m_active_window_shadow;
     RefPtr<Gfx::Bitmap> m_inactive_window_shadow;
     RefPtr<Gfx::Bitmap> m_menu_shadow;
     RefPtr<Gfx::Bitmap> m_taskbar_shadow;
     RefPtr<Gfx::Bitmap> m_tooltip_shadow;
-    DeprecatedString m_last_active_window_shadow_path;
-    DeprecatedString m_last_inactive_window_shadow_path;
-    DeprecatedString m_last_menu_shadow_path;
-    DeprecatedString m_last_taskbar_shadow_path;
-    DeprecatedString m_last_tooltip_shadow_path;
+    ByteString m_last_active_window_shadow_path;
+    ByteString m_last_inactive_window_shadow_path;
+    ByteString m_last_menu_shadow_path;
+    ByteString m_last_taskbar_shadow_path;
+    ByteString m_last_tooltip_shadow_path;
 };
 
 }
diff --git a/Userland/Libraries/LibGUI/AbstractView.cpp b/Userland/Libraries/LibGUI/AbstractView.cpp
index 2b3dd167a76..fe60e404fc6 100644
--- a/Userland/Libraries/LibGUI/AbstractView.cpp
+++ b/Userland/Libraries/LibGUI/AbstractView.cpp
@@ -611,7 +611,7 @@ void AbstractView::keydown_event(KeyEvent& event)
                     }
                     auto index = find_next_search_match(sb.string_view());
                     if (index.is_valid()) {
-                        m_highlighted_search = sb.to_deprecated_string();
+                        m_highlighted_search = sb.to_byte_string();
                         highlight_search(index);
                         start_highlighted_search_timer();
                     }
@@ -637,7 +637,7 @@ void AbstractView::keydown_event(KeyEvent& event)
 
             auto index = find_next_search_match(sb.string_view());
             if (index.is_valid()) {
-                m_highlighted_search = sb.to_deprecated_string();
+                m_highlighted_search = sb.to_byte_string();
                 highlight_search(index);
                 start_highlighted_search_timer();
                 set_cursor(index, SelectionUpdate::None, true);
diff --git a/Userland/Libraries/LibGUI/AbstractView.h b/Userland/Libraries/LibGUI/AbstractView.h
index a1184f05cc8..947090b2b0f 100644
--- a/Userland/Libraries/LibGUI/AbstractView.h
+++ b/Userland/Libraries/LibGUI/AbstractView.h
@@ -199,7 +199,7 @@ private:
 
     RefPtr<Model> m_model;
     ModelSelection m_selection;
-    Optional<DeprecatedString> m_highlighted_search;
+    Optional<ByteString> m_highlighted_search;
     RefPtr<Core::Timer> m_highlighted_search_timer;
     SelectionBehavior m_selection_behavior { SelectionBehavior::SelectItems };
     SelectionMode m_selection_mode { SelectionMode::SingleSelection };
diff --git a/Userland/Libraries/LibGUI/Action.cpp b/Userland/Libraries/LibGUI/Action.cpp
index 1c22b832238..13c992ccdc2 100644
--- a/Userland/Libraries/LibGUI/Action.cpp
+++ b/Userland/Libraries/LibGUI/Action.cpp
@@ -15,52 +15,52 @@
 
 namespace GUI {
 
-NonnullRefPtr<Action> Action::create(DeprecatedString text, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create(ByteString text, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), move(callback), parent));
 }
 
-NonnullRefPtr<Action> Action::create(DeprecatedString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create(ByteString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), move(icon), move(callback), parent));
 }
 
-NonnullRefPtr<Action> Action::create(DeprecatedString text, Shortcut const& shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create(ByteString text, Shortcut const& shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), shortcut, move(callback), parent));
 }
 
-NonnullRefPtr<Action> Action::create(DeprecatedString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create(ByteString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), shortcut, alternate_shortcut, move(callback), parent));
 }
 
-NonnullRefPtr<Action> Action::create(DeprecatedString text, Shortcut const& shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create(ByteString text, Shortcut const& shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), shortcut, Shortcut {}, move(icon), move(callback), parent));
 }
 
-NonnullRefPtr<Action> Action::create(DeprecatedString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create(ByteString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), shortcut, alternate_shortcut, move(icon), move(callback), parent));
 }
 
-NonnullRefPtr<Action> Action::create_checkable(DeprecatedString text, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create_checkable(ByteString text, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), move(callback), parent, true));
 }
 
-NonnullRefPtr<Action> Action::create_checkable(DeprecatedString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create_checkable(ByteString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), move(icon), move(callback), parent, true));
 }
 
-NonnullRefPtr<Action> Action::create_checkable(DeprecatedString text, Shortcut const& shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create_checkable(ByteString text, Shortcut const& shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), shortcut, move(callback), parent, true));
 }
 
-NonnullRefPtr<Action> Action::create_checkable(DeprecatedString text, Shortcut const& shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
+NonnullRefPtr<Action> Action::create_checkable(ByteString text, Shortcut const& shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent)
 {
     return adopt_ref(*new Action(move(text), shortcut, Shortcut {}, move(icon), move(callback), parent, true));
 }
@@ -78,27 +78,27 @@ RefPtr<Action> Action::find_action_for_shortcut(Core::EventReceiver& object, Sho
     return found_action;
 }
 
-Action::Action(DeprecatedString text, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
+Action::Action(ByteString text, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
     : Action(move(text), Shortcut {}, Shortcut {}, nullptr, move(on_activation_callback), parent, checkable)
 {
 }
 
-Action::Action(DeprecatedString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
+Action::Action(ByteString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
     : Action(move(text), Shortcut {}, Shortcut {}, move(icon), move(on_activation_callback), parent, checkable)
 {
 }
 
-Action::Action(DeprecatedString text, Shortcut const& shortcut, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
+Action::Action(ByteString text, Shortcut const& shortcut, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
     : Action(move(text), shortcut, Shortcut {}, nullptr, move(on_activation_callback), parent, checkable)
 {
 }
 
-Action::Action(DeprecatedString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
+Action::Action(ByteString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
     : Action(move(text), shortcut, alternate_shortcut, nullptr, move(on_activation_callback), parent, checkable)
 {
 }
 
-Action::Action(DeprecatedString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
+Action::Action(ByteString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> on_activation_callback, Core::EventReceiver* parent, bool checkable)
     : Core::EventReceiver(parent)
     , on_activation(move(on_activation_callback))
     , m_text(move(text))
@@ -284,31 +284,31 @@ void Action::set_icon(Gfx::Bitmap const* icon)
     });
 }
 
-void Action::set_text(DeprecatedString text)
+void Action::set_text(ByteString text)
 {
     if (m_text == text)
         return;
     m_text = move(text);
     for_each_toolbar_button([&](auto& button) {
-        button.set_text(String::from_deprecated_string(m_text).release_value_but_fixme_should_propagate_errors());
+        button.set_text(String::from_byte_string(m_text).release_value_but_fixme_should_propagate_errors());
     });
     for_each_menu_item([&](auto& menu_item) {
         menu_item.update_from_action({});
     });
 }
 
-DeprecatedString Action::tooltip() const
+ByteString Action::tooltip() const
 {
     return m_tooltip.value_or_lazy_evaluated([this] { return Gfx::parse_ampersand_string(m_text); });
 }
 
-void Action::set_tooltip(DeprecatedString tooltip)
+void Action::set_tooltip(ByteString tooltip)
 {
     if (m_tooltip == tooltip)
         return;
     m_tooltip = move(tooltip);
     for_each_toolbar_button([&](auto& button) {
-        button.set_tooltip(MUST(String::from_deprecated_string(*m_tooltip)));
+        button.set_tooltip(MUST(String::from_byte_string(*m_tooltip)));
     });
     for_each_menu_item([&](auto& menu_item) {
         menu_item.update_from_action({});
@@ -320,7 +320,7 @@ Optional<String> Action::status_tip() const
     if (!m_status_tip.is_empty())
         return m_status_tip;
 
-    auto maybe_parsed_action_text = String::from_deprecated_string(Gfx::parse_ampersand_string(m_text));
+    auto maybe_parsed_action_text = String::from_byte_string(Gfx::parse_ampersand_string(m_text));
     if (maybe_parsed_action_text.is_error())
         return {};
     return maybe_parsed_action_text.release_value();
diff --git a/Userland/Libraries/LibGUI/Action.h b/Userland/Libraries/LibGUI/Action.h
index 298bf8a182a..207dda10e5e 100644
--- a/Userland/Libraries/LibGUI/Action.h
+++ b/Userland/Libraries/LibGUI/Action.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <AK/Badge.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashTable.h>
 #include <AK/NonnullRefPtr.h>
@@ -66,26 +66,26 @@ public:
         WindowLocal,
         ApplicationGlobal,
     };
-    static NonnullRefPtr<Action> create(DeprecatedString text, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
-    static NonnullRefPtr<Action> create(DeprecatedString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
-    static NonnullRefPtr<Action> create(DeprecatedString text, Shortcut const& shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
-    static NonnullRefPtr<Action> create(DeprecatedString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
-    static NonnullRefPtr<Action> create(DeprecatedString text, Shortcut const& shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
-    static NonnullRefPtr<Action> create(DeprecatedString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
-    static NonnullRefPtr<Action> create_checkable(DeprecatedString text, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
-    static NonnullRefPtr<Action> create_checkable(DeprecatedString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
-    static NonnullRefPtr<Action> create_checkable(DeprecatedString text, Shortcut const& shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
-    static NonnullRefPtr<Action> create_checkable(DeprecatedString text, Shortcut const& shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create(ByteString text, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create(ByteString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create(ByteString text, Shortcut const& shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create(ByteString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create(ByteString text, Shortcut const& shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create(ByteString text, Shortcut const& shortcut, Shortcut const& alternate_shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create_checkable(ByteString text, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create_checkable(ByteString text, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create_checkable(ByteString text, Shortcut const& shortcut, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
+    static NonnullRefPtr<Action> create_checkable(ByteString text, Shortcut const& shortcut, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> callback, Core::EventReceiver* parent = nullptr);
 
     static RefPtr<Action> find_action_for_shortcut(Core::EventReceiver& object, Shortcut const& shortcut);
 
     virtual ~Action() override;
 
-    DeprecatedString text() const { return m_text; }
-    void set_text(DeprecatedString);
+    ByteString text() const { return m_text; }
+    void set_text(ByteString);
 
-    DeprecatedString tooltip() const;
-    void set_tooltip(DeprecatedString);
+    ByteString tooltip() const;
+    void set_tooltip(ByteString);
 
     Optional<String> status_tip() const;
     void set_status_tip(String status_tip) { m_status_tip = move(status_tip); }
@@ -136,19 +136,19 @@ public:
     HashTable<MenuItem*> const& menu_items() const { return m_menu_items; }
 
 private:
-    Action(DeprecatedString, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
-    Action(DeprecatedString, Shortcut const&, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
-    Action(DeprecatedString, Shortcut const&, Shortcut const&, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
-    Action(DeprecatedString, Shortcut const&, Shortcut const&, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
-    Action(DeprecatedString, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
+    Action(ByteString, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
+    Action(ByteString, Shortcut const&, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
+    Action(ByteString, Shortcut const&, Shortcut const&, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
+    Action(ByteString, Shortcut const&, Shortcut const&, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
+    Action(ByteString, RefPtr<Gfx::Bitmap const> icon, Function<void(Action&)> = nullptr, Core::EventReceiver* = nullptr, bool checkable = false);
 
     template<typename Callback>
     void for_each_toolbar_button(Callback);
     template<typename Callback>
     void for_each_menu_item(Callback);
 
-    DeprecatedString m_text;
-    Optional<DeprecatedString> m_tooltip;
+    ByteString m_text;
+    Optional<ByteString> m_tooltip;
     String m_status_tip;
     RefPtr<Gfx::Bitmap const> m_icon;
     Shortcut m_shortcut;
diff --git a/Userland/Libraries/LibGUI/Application.cpp b/Userland/Libraries/LibGUI/Application.cpp
index 1e061e43af4..bc58cdcba68 100644
--- a/Userland/Libraries/LibGUI/Application.cpp
+++ b/Userland/Libraries/LibGUI/Application.cpp
@@ -373,7 +373,7 @@ void Application::update_recent_file_actions()
 
 void Application::set_most_recently_open_file(String new_path)
 {
-    Vector<DeprecatedString> new_recent_files_list;
+    Vector<ByteString> new_recent_files_list;
 
     for (size_t i = 0; i < max_recently_open_files(); ++i) {
         static_assert(max_recently_open_files() < 10);
@@ -386,7 +386,7 @@ void Application::set_most_recently_open_file(String new_path)
         return existing_path.view() == new_path;
     });
 
-    new_recent_files_list.prepend(new_path.to_deprecated_string());
+    new_recent_files_list.prepend(new_path.to_byte_string());
 
     for (size_t i = 0; i < max_recently_open_files(); ++i) {
         auto& path = new_recent_files_list[i];
diff --git a/Userland/Libraries/LibGUI/Application.h b/Userland/Libraries/LibGUI/Application.h
index ba27d165ec4..692291898dd 100644
--- a/Userland/Libraries/LibGUI/Application.h
+++ b/Userland/Libraries/LibGUI/Application.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/String.h>
@@ -52,8 +52,8 @@ public:
     void did_create_window(Badge<Window>);
     void did_delete_last_window(Badge<Window>);
 
-    DeprecatedString const& invoked_as() const { return m_invoked_as; }
-    Vector<DeprecatedString> const& args() const { return m_args; }
+    ByteString const& invoked_as() const { return m_invoked_as; }
+    Vector<ByteString> const& args() const { return m_args; }
 
     Gfx::Palette palette() const;
     void set_palette(Gfx::Palette&);
@@ -123,8 +123,8 @@ private:
     bool m_focus_debugging_enabled { false };
     bool m_hover_debugging_enabled { false };
     bool m_dnd_debugging_enabled { false };
-    DeprecatedString m_invoked_as;
-    Vector<DeprecatedString> m_args;
+    ByteString m_invoked_as;
+    Vector<ByteString> m_args;
     WeakPtr<Widget> m_drag_hovered_widget;
     WeakPtr<Widget> m_pending_drop_widget;
 
diff --git a/Userland/Libraries/LibGUI/AutocompleteProvider.cpp b/Userland/Libraries/LibGUI/AutocompleteProvider.cpp
index 585f948b9cc..c83a2a8f306 100644
--- a/Userland/Libraries/LibGUI/AutocompleteProvider.cpp
+++ b/Userland/Libraries/LibGUI/AutocompleteProvider.cpp
@@ -182,7 +182,7 @@ CodeComprehension::AutocompleteResultEntry::HideAutocompleteAfterApplying Autoco
         return hide_when_done;
 
     auto suggestion_index = m_suggestion_view->model()->index(selected_index.row());
-    auto completion = suggestion_index.data((GUI::ModelRole)AutocompleteSuggestionModel::InternalRole::Completion).to_deprecated_string();
+    auto completion = suggestion_index.data((GUI::ModelRole)AutocompleteSuggestionModel::InternalRole::Completion).to_byte_string();
     size_t partial_length = suggestion_index.data((GUI::ModelRole)AutocompleteSuggestionModel::InternalRole::PartialInputLength).to_i64();
     auto hide_after_applying = suggestion_index.data((GUI::ModelRole)AutocompleteSuggestionModel::InternalRole::HideAutocompleteAfterApplying).to_bool();
 
diff --git a/Userland/Libraries/LibGUI/Breadcrumbbar.cpp b/Userland/Libraries/LibGUI/Breadcrumbbar.cpp
index 9d6ccbcac58..9cba948d51a 100644
--- a/Userland/Libraries/LibGUI/Breadcrumbbar.cpp
+++ b/Userland/Libraries/LibGUI/Breadcrumbbar.cpp
@@ -70,11 +70,11 @@ void Breadcrumbbar::clear_segments()
     m_selected_segment = {};
 }
 
-void Breadcrumbbar::append_segment(DeprecatedString text, Gfx::Bitmap const* icon, DeprecatedString data, String tooltip)
+void Breadcrumbbar::append_segment(ByteString text, Gfx::Bitmap const* icon, ByteString data, String tooltip)
 {
     auto& button = add<BreadcrumbButton>();
     button.set_button_style(Gfx::ButtonStyle::Coolbar);
-    button.set_text(String::from_deprecated_string(text).release_value_but_fixme_should_propagate_errors());
+    button.set_text(String::from_byte_string(text).release_value_but_fixme_should_propagate_errors());
     button.set_icon(icon);
     button.set_tooltip(move(tooltip));
     button.set_focus_policy(FocusPolicy::TabFocus);
@@ -124,7 +124,7 @@ void Breadcrumbbar::remove_end_segments(size_t start_segment_index)
         m_selected_segment = {};
 }
 
-Optional<size_t> Breadcrumbbar::find_segment_with_data(DeprecatedString const& data)
+Optional<size_t> Breadcrumbbar::find_segment_with_data(ByteString const& data)
 {
     for (size_t i = 0; i < segment_count(); ++i) {
         if (segment_data(i) == data)
diff --git a/Userland/Libraries/LibGUI/Breadcrumbbar.h b/Userland/Libraries/LibGUI/Breadcrumbbar.h
index 1721b3741aa..c53a3266692 100644
--- a/Userland/Libraries/LibGUI/Breadcrumbbar.h
+++ b/Userland/Libraries/LibGUI/Breadcrumbbar.h
@@ -19,13 +19,13 @@ public:
     virtual ~Breadcrumbbar() override = default;
 
     void clear_segments();
-    void append_segment(DeprecatedString text, Gfx::Bitmap const* icon = nullptr, DeprecatedString data = {}, String tooltip = {});
+    void append_segment(ByteString text, Gfx::Bitmap const* icon = nullptr, ByteString data = {}, String tooltip = {});
     void remove_end_segments(size_t segment_index);
     void relayout();
 
     size_t segment_count() const { return m_segments.size(); }
-    DeprecatedString segment_data(size_t index) const { return m_segments[index].data; }
-    Optional<size_t> find_segment_with_data(DeprecatedString const& data);
+    ByteString segment_data(size_t index) const { return m_segments[index].data; }
+    Optional<size_t> find_segment_with_data(ByteString const& data);
 
     void set_selected_segment(Optional<size_t> index);
     Optional<size_t> selected_segment() const { return m_selected_segment; }
@@ -48,8 +48,8 @@ private:
 
     struct Segment {
         RefPtr<const Gfx::Bitmap> icon;
-        DeprecatedString text;
-        DeprecatedString data;
+        ByteString text;
+        ByteString data;
         int width { 0 };
         int shrunken_width { 0 };
         WeakPtr<GUI::Button> button;
diff --git a/Userland/Libraries/LibGUI/Button.cpp b/Userland/Libraries/LibGUI/Button.cpp
index 6f64273bad3..0a1c992ea92 100644
--- a/Userland/Libraries/LibGUI/Button.cpp
+++ b/Userland/Libraries/LibGUI/Button.cpp
@@ -186,7 +186,7 @@ void Button::set_icon(RefPtr<Gfx::Bitmap const> icon)
     update();
 }
 
-void Button::set_icon_from_path(DeprecatedString const& path)
+void Button::set_icon_from_path(ByteString const& path)
 {
     auto maybe_bitmap = Gfx::Bitmap::load_from_file(path);
     if (maybe_bitmap.is_error()) {
diff --git a/Userland/Libraries/LibGUI/Button.h b/Userland/Libraries/LibGUI/Button.h
index 8dd50fa6750..e0e0e990195 100644
--- a/Userland/Libraries/LibGUI/Button.h
+++ b/Userland/Libraries/LibGUI/Button.h
@@ -29,7 +29,7 @@ public:
     virtual ~Button() override;
 
     void set_icon(RefPtr<Gfx::Bitmap const>);
-    void set_icon_from_path(DeprecatedString const&);
+    void set_icon_from_path(ByteString const&);
     Gfx::Bitmap const* icon() const { return m_icon.ptr(); }
 
     void set_text_alignment(Gfx::TextAlignment text_alignment) { m_text_alignment = text_alignment; }
diff --git a/Userland/Libraries/LibGUI/Calendar.cpp b/Userland/Libraries/LibGUI/Calendar.cpp
index 5aa0c48c7b5..e02b94edc14 100644
--- a/Userland/Libraries/LibGUI/Calendar.cpp
+++ b/Userland/Libraries/LibGUI/Calendar.cpp
@@ -636,7 +636,7 @@ void Calendar::paint_tile(GUI::Painter& painter, GUI::Calendar::Tile& tile, Gfx:
             text_rect = Gfx::IntRect(tile_rect);
         }
 
-        auto display_date = DeprecatedString::number(tile.day);
+        auto display_date = ByteString::number(tile.day);
         if (tile.is_selected && (width < 30 || height < 30))
             painter.draw_rect(tile_rect, palette().base_text());
 
@@ -659,7 +659,7 @@ void Calendar::paint_tile(GUI::Painter& painter, GUI::Calendar::Tile& tile, Gfx:
             set_font(*small_font);
         }
 
-        auto display_date = DeprecatedString::number(tile.day);
+        auto display_date = ByteString::number(tile.day);
         if (tile.is_selected)
             painter.draw_rect(tile_rect, palette().base_text());
 
@@ -820,7 +820,7 @@ void Calendar::doubleclick_event(GUI::MouseEvent& event)
     }
 }
 
-size_t Calendar::day_of_week_index(DeprecatedString const& day_name)
+size_t Calendar::day_of_week_index(ByteString const& day_name)
 {
     auto const& day_names = AK::long_day_names;
     return AK::find_index(day_names.begin(), day_names.end(), day_name);
diff --git a/Userland/Libraries/LibGUI/Calendar.h b/Userland/Libraries/LibGUI/Calendar.h
index a95d919665c..36d0a0c77ae 100644
--- a/Userland/Libraries/LibGUI/Calendar.h
+++ b/Userland/Libraries/LibGUI/Calendar.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibConfig/Listener.h>
 #include <LibCore/DateTime.h>
 #include <LibGUI/AbstractScrollableWidget.h>
@@ -104,7 +104,7 @@ protected:
     Calendar(Core::DateTime date_time = Core::DateTime::now(), Mode mode = Month);
 
 private:
-    static size_t day_of_week_index(DeprecatedString const&);
+    static size_t day_of_week_index(ByteString const&);
 
     virtual void resize_event(GUI::ResizeEvent&) override;
     virtual void mousemove_event(GUI::MouseEvent&) override;
@@ -127,14 +127,14 @@ private:
     bool is_day_in_weekend(DayOfWeek);
 
     struct Day {
-        DeprecatedString name;
+        ByteString name;
         int width { 0 };
         int height { 16 };
     };
     Vector<Day> m_days;
 
     struct MonthTile {
-        DeprecatedString name;
+        ByteString name;
         Gfx::IntRect rect;
         int width { 0 };
         int height { 0 };
diff --git a/Userland/Libraries/LibGUI/Clipboard.cpp b/Userland/Libraries/LibGUI/Clipboard.cpp
index 4c4792e03fc..2f68dd4bf1a 100644
--- a/Userland/Libraries/LibGUI/Clipboard.cpp
+++ b/Userland/Libraries/LibGUI/Clipboard.cpp
@@ -24,7 +24,7 @@ private:
     {
     }
 
-    virtual void clipboard_data_changed(DeprecatedString const& mime_type) override
+    virtual void clipboard_data_changed(ByteString const& mime_type) override
     {
         Clipboard::the().clipboard_data_changed({}, mime_type);
     }
@@ -131,8 +131,8 @@ ErrorOr<Clipboard::DataAndType> Clipboard::DataAndType::from_json(JsonObject con
         return Error::from_string_literal("JsonObject does not contain necessary fields");
 
     DataAndType result;
-    result.data = object.get_deprecated_string("data"sv)->to_byte_buffer();
-    result.mime_type = *object.get_deprecated_string("mime_type"sv);
+    result.data = object.get_byte_string("data"sv)->to_byte_buffer();
+    result.mime_type = *object.get_byte_string("mime_type"sv);
     // FIXME: Also read metadata
 
     return result;
@@ -141,14 +141,14 @@ ErrorOr<Clipboard::DataAndType> Clipboard::DataAndType::from_json(JsonObject con
 ErrorOr<JsonObject> Clipboard::DataAndType::to_json() const
 {
     JsonObject object;
-    object.set("data", TRY(DeprecatedString::from_utf8(data.bytes())));
+    object.set("data", TRY(ByteString::from_utf8(data.bytes())));
     object.set("mime_type", mime_type);
     // FIXME: Also write metadata
 
     return object;
 }
 
-void Clipboard::set_data(ReadonlyBytes data, DeprecatedString const& type, HashMap<DeprecatedString, DeprecatedString> const& metadata)
+void Clipboard::set_data(ReadonlyBytes data, ByteString const& type, HashMap<ByteString, ByteString> const& metadata)
 {
     if (data.is_empty()) {
         connection().async_set_clipboard_data({}, type, metadata.clone().release_value_but_fixme_should_propagate_errors());
@@ -165,14 +165,14 @@ void Clipboard::set_data(ReadonlyBytes data, DeprecatedString const& type, HashM
     connection().async_set_clipboard_data(move(buffer), type, metadata.clone().release_value_but_fixme_should_propagate_errors());
 }
 
-void Clipboard::set_bitmap(Gfx::Bitmap const& bitmap, HashMap<DeprecatedString, DeprecatedString> const& additional_metadata)
+void Clipboard::set_bitmap(Gfx::Bitmap const& bitmap, HashMap<ByteString, ByteString> const& additional_metadata)
 {
-    HashMap<DeprecatedString, DeprecatedString> metadata = additional_metadata.clone().release_value_but_fixme_should_propagate_errors();
-    metadata.set("width", DeprecatedString::number(bitmap.width()));
-    metadata.set("height", DeprecatedString::number(bitmap.height()));
-    metadata.set("scale", DeprecatedString::number(bitmap.scale()));
-    metadata.set("format", DeprecatedString::number((int)bitmap.format()));
-    metadata.set("pitch", DeprecatedString::number(bitmap.pitch()));
+    HashMap<ByteString, ByteString> metadata = additional_metadata.clone().release_value_but_fixme_should_propagate_errors();
+    metadata.set("width", ByteString::number(bitmap.width()));
+    metadata.set("height", ByteString::number(bitmap.height()));
+    metadata.set("scale", ByteString::number(bitmap.scale()));
+    metadata.set("format", ByteString::number((int)bitmap.format()));
+    metadata.set("pitch", ByteString::number(bitmap.pitch()));
     set_data({ bitmap.scanline(0), bitmap.size_in_bytes() }, "image/x-serenityos", move(metadata));
 }
 
@@ -181,7 +181,7 @@ void Clipboard::clear()
     connection().async_set_clipboard_data({}, {}, {});
 }
 
-void Clipboard::clipboard_data_changed(Badge<ConnectionToClipboardServer>, DeprecatedString const& mime_type)
+void Clipboard::clipboard_data_changed(Badge<ConnectionToClipboardServer>, ByteString const& mime_type)
 {
     if (on_change)
         on_change(mime_type);
diff --git a/Userland/Libraries/LibGUI/Clipboard.h b/Userland/Libraries/LibGUI/Clipboard.h
index 95dc00b8b26..6a60c538db2 100644
--- a/Userland/Libraries/LibGUI/Clipboard.h
+++ b/Userland/Libraries/LibGUI/Clipboard.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/JsonObject.h>
@@ -26,13 +26,13 @@ public:
         ClipboardClient();
         virtual ~ClipboardClient();
 
-        virtual void clipboard_content_did_change(DeprecatedString const& mime_type) = 0;
+        virtual void clipboard_content_did_change(ByteString const& mime_type) = 0;
     };
 
     struct DataAndType {
         ByteBuffer data;
-        DeprecatedString mime_type;
-        HashMap<DeprecatedString, DeprecatedString> metadata;
+        ByteString mime_type;
+        HashMap<ByteString, ByteString> metadata;
 
         RefPtr<Gfx::Bitmap> as_bitmap() const;
 
@@ -44,19 +44,19 @@ public:
     static Clipboard& the();
 
     DataAndType fetch_data_and_type() const;
-    DeprecatedString fetch_mime_type() const { return fetch_data_and_type().mime_type; }
+    ByteString fetch_mime_type() const { return fetch_data_and_type().mime_type; }
 
-    void set_data(ReadonlyBytes data, DeprecatedString const& mime_type = "text/plain", HashMap<DeprecatedString, DeprecatedString> const& metadata = {});
+    void set_data(ReadonlyBytes data, ByteString const& mime_type = "text/plain", HashMap<ByteString, ByteString> const& metadata = {});
     void set_plain_text(StringView text) { set_data(text.bytes()); }
-    void set_bitmap(Gfx::Bitmap const&, HashMap<DeprecatedString, DeprecatedString> const& additional_metadata = {});
+    void set_bitmap(Gfx::Bitmap const&, HashMap<ByteString, ByteString> const& additional_metadata = {});
     void clear();
 
-    void clipboard_data_changed(Badge<ConnectionToClipboardServer>, DeprecatedString const& mime_type);
+    void clipboard_data_changed(Badge<ConnectionToClipboardServer>, ByteString const& mime_type);
 
     void register_client(Badge<ClipboardClient>, ClipboardClient& client) { m_clients.set(&client); }
     void unregister_client(Badge<ClipboardClient>, ClipboardClient& client) { m_clients.remove(&client); }
 
-    Function<void(DeprecatedString const& mime_type)> on_change;
+    Function<void(ByteString const& mime_type)> on_change;
 
 private:
     Clipboard() = default;
diff --git a/Userland/Libraries/LibGUI/ColorInput.cpp b/Userland/Libraries/LibGUI/ColorInput.cpp
index d65abf4de47..d26e6bcb7f4 100644
--- a/Userland/Libraries/LibGUI/ColorInput.cpp
+++ b/Userland/Libraries/LibGUI/ColorInput.cpp
@@ -43,7 +43,7 @@ void ColorInput::set_color_internal(Color color, AllowCallback allow_callback, b
         return;
     m_color = color;
     if (change_text)
-        set_text(m_color_has_alpha_channel ? color.to_deprecated_string() : color.to_deprecated_string_without_alpha(), AllowCallback::No);
+        set_text(m_color_has_alpha_channel ? color.to_byte_string() : color.to_byte_string_without_alpha(), AllowCallback::No);
     update();
     if (allow_callback == AllowCallback::Yes && on_change)
         on_change();
diff --git a/Userland/Libraries/LibGUI/ColorInput.h b/Userland/Libraries/LibGUI/ColorInput.h
index 46705529e9e..1cb957f0afc 100644
--- a/Userland/Libraries/LibGUI/ColorInput.h
+++ b/Userland/Libraries/LibGUI/ColorInput.h
@@ -24,8 +24,8 @@ public:
     void set_color(Color, AllowCallback = AllowCallback::Yes);
     Color color() { return m_color; }
 
-    void set_color_picker_title(DeprecatedString title) { m_color_picker_title = move(title); }
-    DeprecatedString color_picker_title() { return m_color_picker_title; }
+    void set_color_picker_title(ByteString title) { m_color_picker_title = move(title); }
+    ByteString color_picker_title() { return m_color_picker_title; }
 
     Function<void()> on_change;
 
@@ -42,7 +42,7 @@ private:
     void set_color_internal(Color, AllowCallback, bool change_text);
 
     Color m_color;
-    DeprecatedString m_color_picker_title { "Color Picker" };
+    ByteString m_color_picker_title { "Color Picker" };
     bool m_color_has_alpha_channel { true };
     bool m_may_be_color_rect_click { false };
 };
diff --git a/Userland/Libraries/LibGUI/ColorPicker.cpp b/Userland/Libraries/LibGUI/ColorPicker.cpp
index 9174c783018..59531413cf8 100644
--- a/Userland/Libraries/LibGUI/ColorPicker.cpp
+++ b/Userland/Libraries/LibGUI/ColorPicker.cpp
@@ -183,7 +183,7 @@ private:
     Color m_col;
 };
 
-ColorPicker::ColorPicker(Color color, Window* parent_window, DeprecatedString title)
+ColorPicker::ColorPicker(Color color, Window* parent_window, ByteString title)
     : Dialog(parent_window)
     , m_original_color(color)
     , m_color(color)
@@ -340,7 +340,7 @@ void ColorPicker::build_ui_custom(Widget& root_container)
     html_label.set_text("HTML:"_string);
 
     m_html_text = html_container.add<GUI::TextBox>();
-    m_html_text->set_text(m_color_has_alpha_channel ? m_color.to_deprecated_string() : m_color.to_deprecated_string_without_alpha());
+    m_html_text->set_text(m_color_has_alpha_channel ? m_color.to_byte_string() : m_color.to_byte_string_without_alpha());
     m_html_text->on_change = [this]() {
         auto color_name = m_html_text->text();
         auto optional_color = Color::from_string(color_name);
@@ -435,7 +435,7 @@ void ColorPicker::update_color_widgets()
 {
     m_preview_widget->set_color(m_color);
 
-    m_html_text->set_text(m_color_has_alpha_channel ? m_color.to_deprecated_string() : m_color.to_deprecated_string_without_alpha());
+    m_html_text->set_text(m_color_has_alpha_channel ? m_color.to_byte_string() : m_color.to_byte_string_without_alpha());
 
     m_red_spinbox->set_value(m_color.red());
     m_green_spinbox->set_value(m_color.green());
diff --git a/Userland/Libraries/LibGUI/ColorPicker.h b/Userland/Libraries/LibGUI/ColorPicker.h
index 79db518d880..341786a8479 100644
--- a/Userland/Libraries/LibGUI/ColorPicker.h
+++ b/Userland/Libraries/LibGUI/ColorPicker.h
@@ -29,7 +29,7 @@ public:
     Function<void(Color)> on_color_changed;
 
 private:
-    explicit ColorPicker(Color, Window* parent_window = nullptr, DeprecatedString title = "Color Picker");
+    explicit ColorPicker(Color, Window* parent_window = nullptr, ByteString title = "Color Picker");
 
     void build_ui();
     void build_ui_custom(Widget& root_container);
diff --git a/Userland/Libraries/LibGUI/ColumnsView.cpp b/Userland/Libraries/LibGUI/ColumnsView.cpp
index 461fd5283f1..6ec3c27ab14 100644
--- a/Userland/Libraries/LibGUI/ColumnsView.cpp
+++ b/Userland/Libraries/LibGUI/ColumnsView.cpp
@@ -158,7 +158,7 @@ void ColumnsView::paint_event(PaintEvent& event)
                 icon_rect.right() + icon_spacing(), row * item_height(),
                 column.width - icon_spacing() - icon_size() - icon_spacing() - icon_spacing() - static_cast<int>(s_arrow_bitmap.width()) - icon_spacing(), item_height()
             };
-            draw_item_text(painter, index, is_selected_row, text_rect, index.data().to_deprecated_string(), font_for_index(index), Gfx::TextAlignment::CenterLeft, Gfx::TextElision::None);
+            draw_item_text(painter, index, is_selected_row, text_rect, index.data().to_byte_string(), font_for_index(index), Gfx::TextAlignment::CenterLeft, Gfx::TextElision::None);
 
             if (is_focused() && index == cursor_index()) {
                 painter.draw_rect(row_rect, palette().color(background_role()));
@@ -231,7 +231,7 @@ void ColumnsView::update_column_sizes()
         for (int row = 0; row < row_count; row++) {
             ModelIndex index = model()->index(row, m_model_column, column.parent_index);
             VERIFY(index.is_valid());
-            auto text = index.data().to_deprecated_string();
+            auto text = index.data().to_byte_string();
             int row_width = icon_spacing() + icon_size() + icon_spacing() + font().width(text) + icon_spacing() + s_arrow_bitmap.width() + icon_spacing();
             if (row_width > column.width)
                 column.width = row_width;
diff --git a/Userland/Libraries/LibGUI/ComboBox.cpp b/Userland/Libraries/LibGUI/ComboBox.cpp
index fee48a11ee1..1e6cc2a25fb 100644
--- a/Userland/Libraries/LibGUI/ComboBox.cpp
+++ b/Userland/Libraries/LibGUI/ComboBox.cpp
@@ -150,7 +150,7 @@ void ComboBox::set_editor_placeholder(StringView placeholder)
     m_editor->set_placeholder(placeholder);
 }
 
-DeprecatedString const& ComboBox::editor_placeholder() const
+ByteString const& ComboBox::editor_placeholder() const
 {
     return m_editor->placeholder();
 }
@@ -179,7 +179,7 @@ void ComboBox::selection_updated(ModelIndex const& index)
 {
     if (index.is_valid()) {
         m_selected_index = index;
-        auto new_value = index.data().to_deprecated_string();
+        auto new_value = index.data().to_byte_string();
         m_editor->set_text(new_value);
     } else {
         m_selected_index.clear();
@@ -285,12 +285,12 @@ void ComboBox::close()
     m_list_window->hide();
 }
 
-DeprecatedString ComboBox::text() const
+ByteString ComboBox::text() const
 {
     return m_editor->text();
 }
 
-void ComboBox::set_text(DeprecatedString const& text, AllowCallback allow_callback)
+void ComboBox::set_text(ByteString const& text, AllowCallback allow_callback)
 {
     m_editor->set_text(text, allow_callback);
 }
diff --git a/Userland/Libraries/LibGUI/ComboBox.h b/Userland/Libraries/LibGUI/ComboBox.h
index 219aaec70e3..55c0a470e30 100644
--- a/Userland/Libraries/LibGUI/ComboBox.h
+++ b/Userland/Libraries/LibGUI/ComboBox.h
@@ -20,8 +20,8 @@ class ComboBox : public Frame {
 public:
     virtual ~ComboBox() override;
 
-    DeprecatedString text() const;
-    void set_text(DeprecatedString const&, AllowCallback = AllowCallback::Yes);
+    ByteString text() const;
+    void set_text(ByteString const&, AllowCallback = AllowCallback::Yes);
 
     void open();
     void close();
@@ -42,12 +42,12 @@ public:
     void set_model_column(int);
 
     void set_editor_placeholder(StringView placeholder);
-    DeprecatedString const& editor_placeholder() const;
+    ByteString const& editor_placeholder() const;
 
     int max_visible_items() const { return m_max_visible_items; }
     void set_max_visible_items(int max) { m_max_visible_items = max; }
 
-    Function<void(DeprecatedString const&, ModelIndex const&)> on_change;
+    Function<void(ByteString const&, ModelIndex const&)> on_change;
     Function<void()> on_return_pressed;
 
 protected:
diff --git a/Userland/Libraries/LibGUI/Command.h b/Userland/Libraries/LibGUI/Command.h
index a9a8ef25704..28cae113257 100644
--- a/Userland/Libraries/LibGUI/Command.h
+++ b/Userland/Libraries/LibGUI/Command.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 
 namespace GUI {
 
@@ -18,7 +18,7 @@ public:
     virtual void undo() { }
     virtual void redo() { }
 
-    virtual DeprecatedString action_text() const { return {}; }
+    virtual ByteString action_text() const { return {}; }
     virtual bool merge_with(Command const&) { return false; }
 
 protected:
diff --git a/Userland/Libraries/LibGUI/CommandPalette.cpp b/Userland/Libraries/LibGUI/CommandPalette.cpp
index 946d756249b..6578f691dd8 100644
--- a/Userland/Libraries/LibGUI/CommandPalette.cpp
+++ b/Userland/Libraries/LibGUI/CommandPalette.cpp
@@ -129,7 +129,7 @@ public:
         case Column::Shortcut:
             if (!action.shortcut().is_valid())
                 return "";
-            return action.shortcut().to_deprecated_string();
+            return action.shortcut().to_byte_string();
         }
 
         VERIFY_NOT_REACHED();
@@ -141,21 +141,21 @@ public:
         if (needle.is_empty())
             return { TriState::True };
 
-        auto haystack = DeprecatedString::formatted("{} {}", menu_name(index), action_text(index));
+        auto haystack = ByteString::formatted("{} {}", menu_name(index), action_text(index));
         auto match_result = fuzzy_match(needle, haystack);
         if (match_result.score > 0)
             return { TriState::True, match_result.score };
         return { TriState::False };
     }
 
-    static DeprecatedString action_text(ModelIndex const& index)
+    static ByteString action_text(ModelIndex const& index)
     {
         auto& action = *static_cast<GUI::Action*>(index.internal_data());
 
         return Gfx::parse_ampersand_string(action.text());
     }
 
-    static DeprecatedString menu_name(ModelIndex const& index)
+    static ByteString menu_name(ModelIndex const& index)
     {
         auto& action = *static_cast<GUI::Action*>(index.internal_data());
         if (action.menu_items().is_empty())
diff --git a/Userland/Libraries/LibGUI/CommonActions.cpp b/Userland/Libraries/LibGUI/CommonActions.cpp
index dcc5a4119ef..bf907a670d9 100644
--- a/Userland/Libraries/LibGUI/CommonActions.cpp
+++ b/Userland/Libraries/LibGUI/CommonActions.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/WeakPtr.h>
 #include <LibCore/Version.h>
@@ -20,7 +20,7 @@ namespace CommonActions {
 NonnullRefPtr<Action> make_about_action(String const& app_name, Icon const& app_icon, Window* parent)
 {
     auto weak_parent = AK::make_weak_ptr_if_nonnull<Window>(parent);
-    auto action = Action::create(DeprecatedString::formatted("&About {}", app_name), app_icon.bitmap_for_size(16), [=](auto&) {
+    auto action = Action::create(ByteString::formatted("&About {}", app_name), app_icon.bitmap_for_size(16), [=](auto&) {
         AboutDialog::show(
             app_name,
             Core::Version::read_long_version_string().release_value_but_fixme_should_propagate_errors(),
diff --git a/Userland/Libraries/LibGUI/CommonLocationsProvider.cpp b/Userland/Libraries/LibGUI/CommonLocationsProvider.cpp
index 5928651cbd0..0c9afe3dd74 100644
--- a/Userland/Libraries/LibGUI/CommonLocationsProvider.cpp
+++ b/Userland/Libraries/LibGUI/CommonLocationsProvider.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/JsonArray.h>
 #include <AK/JsonObject.h>
 #include <AK/Vector.h>
@@ -24,7 +24,7 @@ static void initialize_if_needed()
     if (s_initialized)
         return;
 
-    auto user_config = DeprecatedString::formatted("{}/CommonLocations.json", Core::StandardPaths::config_directory());
+    auto user_config = ByteString::formatted("{}/CommonLocations.json", Core::StandardPaths::config_directory());
     if (FileSystem::exists(user_config)) {
         auto maybe_error = CommonLocationsProvider::load_from_json(user_config);
         if (!maybe_error.is_error())
@@ -56,8 +56,8 @@ ErrorOr<void> CommonLocationsProvider::load_from_json(StringView json_path)
         if (!entry_value.is_object())
             continue;
         auto entry = entry_value.as_object();
-        auto name = entry.get_deprecated_string("name"sv).value_or({});
-        auto path = entry.get_deprecated_string("path"sv).value_or({});
+        auto name = entry.get_byte_string("name"sv).value_or({});
+        auto path = entry.get_byte_string("path"sv).value_or({});
         TRY(s_common_locations.try_append({ name, path }));
     }
 
diff --git a/Userland/Libraries/LibGUI/CommonLocationsProvider.h b/Userland/Libraries/LibGUI/CommonLocationsProvider.h
index b094f8b4828..05785e46ece 100644
--- a/Userland/Libraries/LibGUI/CommonLocationsProvider.h
+++ b/Userland/Libraries/LibGUI/CommonLocationsProvider.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <LibGUI/Forward.h>
 #include <sys/types.h>
@@ -16,8 +16,8 @@ namespace GUI {
 class CommonLocationsProvider {
 public:
     struct CommonLocation {
-        DeprecatedString name;
-        DeprecatedString path;
+        ByteString name;
+        ByteString path;
     };
 
     static ErrorOr<void> load_from_json(StringView json_path);
diff --git a/Userland/Libraries/LibGUI/ConnectionToWindowManagerServer.cpp b/Userland/Libraries/LibGUI/ConnectionToWindowManagerServer.cpp
index 81c29a85687..5217d61a54e 100644
--- a/Userland/Libraries/LibGUI/ConnectionToWindowManagerServer.cpp
+++ b/Userland/Libraries/LibGUI/ConnectionToWindowManagerServer.cpp
@@ -21,7 +21,7 @@ ConnectionToWindowManagerServer& ConnectionToWindowManagerServer::the()
 
 void ConnectionToWindowManagerServer::window_state_changed(i32 wm_id, i32 client_id, i32 window_id,
     u32 workspace_row, u32 workspace_column, bool is_active, bool is_blocked, bool is_minimized, bool is_frameless,
-    i32 window_type, DeprecatedString const& title, Gfx::IntRect const& rect, Optional<i32> const& progress)
+    i32 window_type, ByteString const& title, Gfx::IntRect const& rect, Optional<i32> const& progress)
 {
     if (auto* window = Window::from_window_id(wm_id))
         Core::EventLoop::current().post_event(*window, make<WMWindowStateChangedEvent>(client_id, window_id, title, rect, workspace_row, workspace_column, is_active, is_blocked, static_cast<WindowType>(window_type), is_minimized, is_frameless, progress));
@@ -82,7 +82,7 @@ void ConnectionToWindowManagerServer::workspace_changed(i32 wm_id, u32 row, u32
         Core::EventLoop::current().post_event(*window, make<WMWorkspaceChangedEvent>(wm_id, row, column));
 }
 
-void ConnectionToWindowManagerServer::keymap_changed(i32 wm_id, DeprecatedString const& keymap)
+void ConnectionToWindowManagerServer::keymap_changed(i32 wm_id, ByteString const& keymap)
 {
     if (auto* window = Window::from_window_id(wm_id))
         Core::EventLoop::current().post_event(*window, make<WMKeymapChangedEvent>(wm_id, keymap));
diff --git a/Userland/Libraries/LibGUI/ConnectionToWindowManagerServer.h b/Userland/Libraries/LibGUI/ConnectionToWindowManagerServer.h
index bee183c2ec0..143a5588289 100644
--- a/Userland/Libraries/LibGUI/ConnectionToWindowManagerServer.h
+++ b/Userland/Libraries/LibGUI/ConnectionToWindowManagerServer.h
@@ -29,7 +29,7 @@ private:
     }
 
     virtual void window_removed(i32, i32, i32) override;
-    virtual void window_state_changed(i32, i32, i32, u32, u32, bool, bool, bool, bool, i32, DeprecatedString const&, Gfx::IntRect const&, Optional<i32> const&) override;
+    virtual void window_state_changed(i32, i32, i32, u32, u32, bool, bool, bool, bool, i32, ByteString const&, Gfx::IntRect const&, Optional<i32> const&) override;
     virtual void window_icon_bitmap_changed(i32, i32, i32, Gfx::ShareableBitmap const&) override;
     virtual void window_rect_changed(i32, i32, i32, Gfx::IntRect const&) override;
     virtual void applet_area_size_changed(i32, Gfx::IntSize) override;
@@ -38,7 +38,7 @@ private:
     virtual void super_d_key_pressed(i32) override;
     virtual void super_digit_key_pressed(i32, u8) override;
     virtual void workspace_changed(i32, u32, u32) override;
-    virtual void keymap_changed(i32, DeprecatedString const&) override;
+    virtual void keymap_changed(i32, ByteString const&) override;
     virtual void add_to_quick_launch(i32, pid_t) override;
 };
 
diff --git a/Userland/Libraries/LibGUI/ConnectionToWindowServer.cpp b/Userland/Libraries/LibGUI/ConnectionToWindowServer.cpp
index 3d9dd27f0e9..fe1c6fc51ee 100644
--- a/Userland/Libraries/LibGUI/ConnectionToWindowServer.cpp
+++ b/Userland/Libraries/LibGUI/ConnectionToWindowServer.cpp
@@ -57,7 +57,7 @@ ConnectionToWindowServer::ConnectionToWindowServer(NonnullOwnPtr<Core::LocalSock
     m_client_id = message->client_id();
 }
 
-void ConnectionToWindowServer::fast_greet(Vector<Gfx::IntRect> const&, u32, u32, u32, Core::AnonymousBuffer const&, DeprecatedString const&, DeprecatedString const&, DeprecatedString const&, Vector<bool> const&, i32)
+void ConnectionToWindowServer::fast_greet(Vector<Gfx::IntRect> const&, u32, u32, u32, Core::AnonymousBuffer const&, ByteString const&, ByteString const&, ByteString const&, Vector<bool> const&, i32)
 {
     // NOTE: This message is handled in the constructor.
 }
@@ -73,7 +73,7 @@ void ConnectionToWindowServer::update_system_theme(Core::AnonymousBuffer const&
     Application::the()->dispatch_event(*make<ThemeChangeEvent>());
 }
 
-void ConnectionToWindowServer::update_system_fonts(DeprecatedString const& default_font_query, DeprecatedString const& fixed_width_font_query, DeprecatedString const& window_title_font_query)
+void ConnectionToWindowServer::update_system_fonts(ByteString const& default_font_query, ByteString const& fixed_width_font_query, ByteString const& window_title_font_query)
 {
     Gfx::FontDatabase::set_default_font_query(default_font_query);
     Gfx::FontDatabase::set_fixed_width_font_query(fixed_width_font_query);
@@ -155,24 +155,24 @@ static Action* action_for_shortcut(Window& window, Shortcut const& shortcut)
     if (!shortcut.is_valid())
         return nullptr;
 
-    dbgln_if(KEYBOARD_SHORTCUTS_DEBUG, "Looking up action for {}", shortcut.to_deprecated_string());
+    dbgln_if(KEYBOARD_SHORTCUTS_DEBUG, "Looking up action for {}", shortcut.to_byte_string());
 
     for (auto* widget = window.focused_widget(); widget; widget = widget->parent_widget()) {
         if (auto* action = widget->action_for_shortcut(shortcut)) {
-            dbgln_if(KEYBOARD_SHORTCUTS_DEBUG, "  > Focused widget {} gave action: {} {} (enabled: {}, shortcut: {}, alt-shortcut: {})", *widget, action, action->text(), action->is_enabled(), action->shortcut().to_deprecated_string(), action->alternate_shortcut().to_deprecated_string());
+            dbgln_if(KEYBOARD_SHORTCUTS_DEBUG, "  > Focused widget {} gave action: {} {} (enabled: {}, shortcut: {}, alt-shortcut: {})", *widget, action, action->text(), action->is_enabled(), action->shortcut().to_byte_string(), action->alternate_shortcut().to_byte_string());
             return action;
         }
     }
 
     if (auto* action = window.action_for_shortcut(shortcut)) {
-        dbgln_if(KEYBOARD_SHORTCUTS_DEBUG, "  > Asked window {}, got action: {} {} (enabled: {}, shortcut: {}, alt-shortcut: {})", window, action, action->text(), action->is_enabled(), action->shortcut().to_deprecated_string(), action->alternate_shortcut().to_deprecated_string());
+        dbgln_if(KEYBOARD_SHORTCUTS_DEBUG, "  > Asked window {}, got action: {} {} (enabled: {}, shortcut: {}, alt-shortcut: {})", window, action, action->text(), action->is_enabled(), action->shortcut().to_byte_string(), action->alternate_shortcut().to_byte_string());
         return action;
     }
 
     // NOTE: Application-global shortcuts are ignored while a blocking modal window is up.
     if (!window.is_blocking() && !window.is_popup()) {
         if (auto* action = Application::the()->action_for_shortcut(shortcut)) {
-            dbgln_if(KEYBOARD_SHORTCUTS_DEBUG, "  > Asked application, got action: {} {} (enabled: {}, shortcut: {}, alt-shortcut: {})", action, action->text(), action->is_enabled(), action->shortcut().to_deprecated_string(), action->alternate_shortcut().to_deprecated_string());
+            dbgln_if(KEYBOARD_SHORTCUTS_DEBUG, "  > Asked application, got action: {} {} (enabled: {}, shortcut: {}, alt-shortcut: {})", action, action->text(), action->is_enabled(), action->shortcut().to_byte_string(), action->alternate_shortcut().to_byte_string());
             return action;
         }
     }
@@ -349,7 +349,7 @@ void ConnectionToWindowServer::applet_area_rect_changed(Gfx::IntRect const& rect
     });
 }
 
-void ConnectionToWindowServer::drag_dropped(i32 window_id, Gfx::IntPoint mouse_position, DeprecatedString const& text, HashMap<String, ByteBuffer> const& mime_data)
+void ConnectionToWindowServer::drag_dropped(i32 window_id, Gfx::IntPoint mouse_position, ByteString const& text, HashMap<String, ByteBuffer> const& mime_data)
 {
     if (auto* window = Window::from_window_id(window_id)) {
         auto mime_data_obj = Core::MimeData::construct(mime_data);
diff --git a/Userland/Libraries/LibGUI/ConnectionToWindowServer.h b/Userland/Libraries/LibGUI/ConnectionToWindowServer.h
index 13283cbcbc2..f041f492096 100644
--- a/Userland/Libraries/LibGUI/ConnectionToWindowServer.h
+++ b/Userland/Libraries/LibGUI/ConnectionToWindowServer.h
@@ -24,7 +24,7 @@ public:
 private:
     ConnectionToWindowServer(NonnullOwnPtr<Core::LocalSocket>);
 
-    virtual void fast_greet(Vector<Gfx::IntRect> const&, u32, u32, u32, Core::AnonymousBuffer const&, DeprecatedString const&, DeprecatedString const&, DeprecatedString const&, Vector<bool> const&, i32) override;
+    virtual void fast_greet(Vector<Gfx::IntRect> const&, u32, u32, u32, Core::AnonymousBuffer const&, ByteString const&, ByteString const&, ByteString const&, Vector<bool> const&, i32) override;
     virtual void paint(i32, Gfx::IntSize, Vector<Gfx::IntRect> const&) override;
     virtual void mouse_move(i32, Gfx::IntPoint, u32, u32, u32, i32, i32, i32, i32, bool, Vector<String> const&) override;
     virtual void mouse_down(i32, Gfx::IntPoint, u32, u32, u32, i32, i32, i32, i32) override;
@@ -48,11 +48,11 @@ private:
     virtual void menu_visibility_did_change(i32, bool) override;
     virtual void screen_rects_changed(Vector<Gfx::IntRect> const&, u32, u32, u32) override;
     virtual void applet_area_rect_changed(Gfx::IntRect const&) override;
-    virtual void drag_dropped(i32, Gfx::IntPoint, DeprecatedString const&, HashMap<String, ByteBuffer> const&) override;
+    virtual void drag_dropped(i32, Gfx::IntPoint, ByteString const&, HashMap<String, ByteBuffer> const&) override;
     virtual void drag_accepted() override;
     virtual void drag_cancelled() override;
     virtual void update_system_theme(Core::AnonymousBuffer const&) override;
-    virtual void update_system_fonts(DeprecatedString const&, DeprecatedString const&, DeprecatedString const&) override;
+    virtual void update_system_fonts(ByteString const&, ByteString const&, ByteString const&) override;
     virtual void update_system_effects(Vector<bool> const&) override;
     virtual void window_state_changed(i32, bool, bool, bool) override;
     virtual void display_link_notification() override;
diff --git a/Userland/Libraries/LibGUI/Desktop.cpp b/Userland/Libraries/LibGUI/Desktop.cpp
index 1fa40eff4b0..9cfd331be08 100644
--- a/Userland/Libraries/LibGUI/Desktop.cpp
+++ b/Userland/Libraries/LibGUI/Desktop.cpp
@@ -49,7 +49,7 @@ void Desktop::set_wallpaper_mode(StringView mode)
     ConnectionToWindowServer::the().async_set_wallpaper_mode(mode);
 }
 
-DeprecatedString Desktop::wallpaper_path() const
+ByteString Desktop::wallpaper_path() const
 {
     return Config::read_string("WindowManager"sv, "Background"sv, "Wallpaper"sv);
 }
diff --git a/Userland/Libraries/LibGUI/Desktop.h b/Userland/Libraries/LibGUI/Desktop.h
index 4a6808d9094..ae1aa33226b 100644
--- a/Userland/Libraries/LibGUI/Desktop.h
+++ b/Userland/Libraries/LibGUI/Desktop.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <LibGUI/Forward.h>
 #include <LibGUI/SystemEffects.h>
@@ -31,7 +31,7 @@ public:
 
     void set_wallpaper_mode(StringView mode);
 
-    DeprecatedString wallpaper_path() const;
+    ByteString wallpaper_path() const;
     RefPtr<Gfx::Bitmap> wallpaper_bitmap() const;
     bool set_wallpaper(RefPtr<Gfx::Bitmap const> wallpaper_bitmap, Optional<StringView> path);
 
diff --git a/Userland/Libraries/LibGUI/DragOperation.cpp b/Userland/Libraries/LibGUI/DragOperation.cpp
index 4ce9b1045ea..5170bb8c18c 100644
--- a/Userland/Libraries/LibGUI/DragOperation.cpp
+++ b/Userland/Libraries/LibGUI/DragOperation.cpp
@@ -73,7 +73,7 @@ void DragOperation::notify_cancelled(Badge<ConnectionToWindowServer>)
         s_current_drag_operation->done(Outcome::Cancelled);
 }
 
-void DragOperation::set_text(DeprecatedString const& text)
+void DragOperation::set_text(ByteString const& text)
 {
     if (!m_mime_data)
         m_mime_data = Core::MimeData::construct();
@@ -86,7 +86,7 @@ void DragOperation::set_bitmap(Gfx::Bitmap const* bitmap)
     if (bitmap)
         m_mime_data->set_data("image/x-raw-bitmap"_string, bitmap->serialize_to_byte_buffer().release_value_but_fixme_should_propagate_errors());
 }
-void DragOperation::set_data(String const& data_type, DeprecatedString const& data)
+void DragOperation::set_data(String const& data_type, ByteString const& data)
 {
     if (!m_mime_data)
         m_mime_data = Core::MimeData::construct();
diff --git a/Userland/Libraries/LibGUI/DragOperation.h b/Userland/Libraries/LibGUI/DragOperation.h
index 160f25ecb38..ad7186d141f 100644
--- a/Userland/Libraries/LibGUI/DragOperation.h
+++ b/Userland/Libraries/LibGUI/DragOperation.h
@@ -27,9 +27,9 @@ public:
     virtual ~DragOperation() override = default;
 
     void set_mime_data(RefPtr<Core::MimeData> mime_data) { m_mime_data = move(mime_data); }
-    void set_text(DeprecatedString const& text);
+    void set_text(ByteString const& text);
     void set_bitmap(Gfx::Bitmap const* bitmap);
-    void set_data(String const& data_type, DeprecatedString const& data);
+    void set_data(String const& data_type, ByteString const& data);
 
     Outcome exec();
     Outcome outcome() const { return m_outcome; }
diff --git a/Userland/Libraries/LibGUI/DynamicWidgetContainer.cpp b/Userland/Libraries/LibGUI/DynamicWidgetContainer.cpp
index 0deeaafc73d..115bb8acf52 100644
--- a/Userland/Libraries/LibGUI/DynamicWidgetContainer.cpp
+++ b/Userland/Libraries/LibGUI/DynamicWidgetContainer.cpp
@@ -144,7 +144,7 @@ void DynamicWidgetContainer::restore_view_state()
 
             order_or_error.value().as_array().for_each([&](auto& section_label) {
                 for (auto& container : containers) {
-                    if (container.section_label() == section_label.to_deprecated_string())
+                    if (container.section_label() == section_label.to_byte_string())
                         new_child_order.append(container);
                 }
             });
@@ -227,7 +227,7 @@ ErrorOr<void> DynamicWidgetContainer::detach_widgets()
 {
     if (!m_detached_widgets_window.has_value()) {
         auto detached_window = TRY(GUI::Window::try_create());
-        detached_window->set_title(section_label().to_deprecated_string());
+        detached_window->set_title(section_label().to_byte_string());
         detached_window->set_window_type(WindowType::Normal);
         if (has_detached_size())
             detached_window->resize(detached_size());
diff --git a/Userland/Libraries/LibGUI/EditingEngine.cpp b/Userland/Libraries/LibGUI/EditingEngine.cpp
index 9b62133ab2f..1f3192017a1 100644
--- a/Userland/Libraries/LibGUI/EditingEngine.cpp
+++ b/Userland/Libraries/LibGUI/EditingEngine.cpp
@@ -423,7 +423,7 @@ bool MoveLineUpOrDownCommand::merge_with(GUI::Command const&)
     return false;
 }
 
-DeprecatedString MoveLineUpOrDownCommand::action_text() const
+ByteString MoveLineUpOrDownCommand::action_text() const
 {
     return "Move a line";
 }
diff --git a/Userland/Libraries/LibGUI/EditingEngine.h b/Userland/Libraries/LibGUI/EditingEngine.h
index 8a6d25859aa..4a3be585001 100644
--- a/Userland/Libraries/LibGUI/EditingEngine.h
+++ b/Userland/Libraries/LibGUI/EditingEngine.h
@@ -92,7 +92,7 @@ public:
     virtual void undo() override;
     virtual void redo() override;
     bool merge_with(GUI::Command const&) override;
-    DeprecatedString action_text() const override;
+    ByteString action_text() const override;
 
     static bool valid_operation(EditingEngine& engine, VerticalDirection direction);
 
diff --git a/Userland/Libraries/LibGUI/EmojiInputDialog.cpp b/Userland/Libraries/LibGUI/EmojiInputDialog.cpp
index 86bab699cbf..22f0659e9d7 100644
--- a/Userland/Libraries/LibGUI/EmojiInputDialog.cpp
+++ b/Userland/Libraries/LibGUI/EmojiInputDialog.cpp
@@ -67,7 +67,7 @@ EmojiInputDialog::EmojiInputDialog(Window* parent_window)
 
     for (auto const& category : s_emoji_groups) {
         auto name = Unicode::emoji_group_to_string(category.group);
-        DeprecatedString tooltip = name;
+        ByteString tooltip = name;
 
         auto set_filter_action = Action::create_checkable(
             category.representative_emoji,
@@ -126,7 +126,7 @@ auto EmojiInputDialog::supported_emoji() -> Vector<Emoji>
             builder.append_code_point(*code_point);
             code_points.append(*code_point);
         });
-        auto text = builder.to_deprecated_string();
+        auto text = builder.to_byte_string();
 
         auto emoji = Unicode::find_emoji_for_code_points(code_points);
         if (!emoji.has_value()) {
@@ -135,7 +135,7 @@ auto EmojiInputDialog::supported_emoji() -> Vector<Emoji>
             emoji->display_order = NumericLimits<u32>::max();
         }
 
-        auto button = Button::construct(String::from_deprecated_string(text).release_value_but_fixme_should_propagate_errors());
+        auto button = Button::construct(String::from_byte_string(text).release_value_but_fixme_should_propagate_errors());
         button->set_fixed_size(button_size, button_size);
         button->set_button_style(Gfx::ButtonStyle::Coolbar);
         button->on_click = [this, text](auto) mutable {
diff --git a/Userland/Libraries/LibGUI/EmojiInputDialog.h b/Userland/Libraries/LibGUI/EmojiInputDialog.h
index 82e0be40560..86353c23b06 100644
--- a/Userland/Libraries/LibGUI/EmojiInputDialog.h
+++ b/Userland/Libraries/LibGUI/EmojiInputDialog.h
@@ -19,11 +19,11 @@ class EmojiInputDialog final : public Dialog {
     struct Emoji {
         RefPtr<Button> button;
         Unicode::Emoji emoji;
-        DeprecatedString text;
+        ByteString text;
     };
 
 public:
-    DeprecatedString const& selected_emoji_text() const { return m_selected_emoji_text; }
+    ByteString const& selected_emoji_text() const { return m_selected_emoji_text; }
 
 private:
     explicit EmojiInputDialog(Window* parent_window);
@@ -40,7 +40,7 @@ private:
     RefPtr<Widget> m_emojis_widget;
     Vector<Emoji> m_emojis;
     Emoji const* m_first_displayed_emoji { nullptr };
-    DeprecatedString m_selected_emoji_text;
+    ByteString m_selected_emoji_text;
 };
 
 }
diff --git a/Userland/Libraries/LibGUI/Event.cpp b/Userland/Libraries/LibGUI/Event.cpp
index 549e393f811..5952407be51 100644
--- a/Userland/Libraries/LibGUI/Event.cpp
+++ b/Userland/Libraries/LibGUI/Event.cpp
@@ -12,7 +12,7 @@
 
 namespace GUI {
 
-DropEvent::DropEvent(Gfx::IntPoint position, DeprecatedString const& text, NonnullRefPtr<Core::MimeData const> mime_data)
+DropEvent::DropEvent(Gfx::IntPoint position, ByteString const& text, NonnullRefPtr<Core::MimeData const> mime_data)
     : Event(Event::Drop)
     , m_position(position)
     , m_text(text)
@@ -20,9 +20,9 @@ DropEvent::DropEvent(Gfx::IntPoint position, DeprecatedString const& text, Nonnu
 {
 }
 
-DeprecatedString KeyEvent::to_deprecated_string() const
+ByteString KeyEvent::to_byte_string() const
 {
-    Vector<DeprecatedString, 8> parts;
+    Vector<ByteString, 8> parts;
 
     if (m_modifiers & Mod_Ctrl)
         parts.append("Ctrl");
@@ -44,7 +44,7 @@ DeprecatedString KeyEvent::to_deprecated_string() const
         if (i != parts.size() - 1)
             builder.append('+');
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 ActionEvent::ActionEvent(Type type, Action& action)
diff --git a/Userland/Libraries/LibGUI/Event.h b/Userland/Libraries/LibGUI/Event.h
index 2c2e5744123..12cf3194061 100644
--- a/Userland/Libraries/LibGUI/Event.h
+++ b/Userland/Libraries/LibGUI/Event.h
@@ -183,7 +183,7 @@ public:
     {
     }
 
-    DeprecatedString const& title() const { return m_title; }
+    ByteString const& title() const { return m_title; }
     Gfx::IntRect const& rect() const { return m_rect; }
     bool is_active() const { return m_active; }
     bool is_blocked() const { return m_blocked; }
@@ -195,7 +195,7 @@ public:
     unsigned workspace_column() const { return m_workspace_column; }
 
 private:
-    DeprecatedString m_title;
+    ByteString m_title;
     Gfx::IntRect m_rect;
     WindowType m_window_type;
     unsigned m_workspace_row;
@@ -254,16 +254,16 @@ private:
 
 class WMKeymapChangedEvent : public WMEvent {
 public:
-    explicit WMKeymapChangedEvent(int client_id, DeprecatedString const& keymap)
+    explicit WMKeymapChangedEvent(int client_id, ByteString const& keymap)
         : WMEvent(Event::Type::WM_KeymapChanged, client_id, 0)
         , m_keymap(keymap)
     {
     }
 
-    DeprecatedString const& keymap() const { return m_keymap; }
+    ByteString const& keymap() const { return m_keymap; }
 
 private:
-    const DeprecatedString m_keymap;
+    const ByteString m_keymap;
 };
 
 class WMAddToQuickLaunchEvent : public WMEvent {
@@ -403,15 +403,15 @@ public:
     bool super() const { return m_modifiers & Mod_Super; }
     u8 modifiers() const { return m_modifiers; }
     u32 code_point() const { return m_code_point; }
-    DeprecatedString text() const
+    ByteString text() const
     {
         StringBuilder sb;
         sb.append_code_point(m_code_point);
-        return sb.to_deprecated_string();
+        return sb.to_byte_string();
     }
     u32 scancode() const { return m_scancode; }
 
-    DeprecatedString to_deprecated_string() const;
+    ByteString to_byte_string() const;
 
     bool is_arrow_key() const
     {
@@ -494,17 +494,17 @@ private:
 
 class DropEvent final : public Event {
 public:
-    DropEvent(Gfx::IntPoint, DeprecatedString const& text, NonnullRefPtr<Core::MimeData const> mime_data);
+    DropEvent(Gfx::IntPoint, ByteString const& text, NonnullRefPtr<Core::MimeData const> mime_data);
 
     ~DropEvent() = default;
 
     Gfx::IntPoint position() const { return m_position; }
-    DeprecatedString const& text() const { return m_text; }
+    ByteString const& text() const { return m_text; }
     Core::MimeData const& mime_data() const { return m_mime_data; }
 
 private:
     Gfx::IntPoint m_position;
-    DeprecatedString m_text;
+    ByteString m_text;
     NonnullRefPtr<Core::MimeData const> m_mime_data;
 };
 
diff --git a/Userland/Libraries/LibGUI/FileIconProvider.cpp b/Userland/Libraries/LibGUI/FileIconProvider.cpp
index d3fa873e631..4a05b00b4a6 100644
--- a/Userland/Libraries/LibGUI/FileIconProvider.cpp
+++ b/Userland/Libraries/LibGUI/FileIconProvider.cpp
@@ -6,7 +6,7 @@
  */
 
 #include <AK/Array.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <LibCore/ConfigFile.h>
 #include <LibCore/MappedFile.h>
@@ -42,8 +42,8 @@ static Icon s_filetype_image_icon;
 static RefPtr<Gfx::Bitmap> s_symlink_emblem;
 static RefPtr<Gfx::Bitmap> s_symlink_emblem_small;
 
-static HashMap<DeprecatedString, Icon> s_filetype_icons;
-static HashMap<DeprecatedString, Vector<DeprecatedString>> s_filetype_patterns;
+static HashMap<ByteString, Icon> s_filetype_icons;
+static HashMap<ByteString, Vector<ByteString>> s_filetype_patterns;
 
 static void initialize_executable_icon_if_needed()
 {
@@ -91,7 +91,7 @@ static void initialize_if_needed()
     initialize_executable_icon_if_needed();
 
     for (auto& filetype : config->keys("Icons")) {
-        s_filetype_icons.set(filetype, Icon::default_icon(DeprecatedString::formatted("filetype-{}", filetype)));
+        s_filetype_icons.set(filetype, Icon::default_icon(ByteString::formatted("filetype-{}", filetype)));
         s_filetype_patterns.set(filetype, config->read_entry("Icons", filetype).split(','));
     }
 
@@ -154,9 +154,9 @@ Icon FileIconProvider::icon_for_path(StringView path)
     return icon_for_path(path, stat_or_error.release_value().st_mode);
 }
 
-Icon FileIconProvider::icon_for_executable(DeprecatedString const& path)
+Icon FileIconProvider::icon_for_executable(ByteString const& path)
 {
-    static HashMap<DeprecatedString, Icon> app_icon_cache;
+    static HashMap<ByteString, Icon> app_icon_cache;
 
     if (auto it = app_icon_cache.find(path); it != app_icon_cache.end())
         return it->value;
@@ -265,7 +265,7 @@ Icon FileIconProvider::icon_for_path(StringView path, mode_t mode)
         if (raw_symlink_target.starts_with('/')) {
             target_path = raw_symlink_target;
         } else {
-            auto error_or_path = FileSystem::real_path(DeprecatedString::formatted("{}/{}", LexicalPath::dirname(path), raw_symlink_target));
+            auto error_or_path = FileSystem::real_path(ByteString::formatted("{}/{}", LexicalPath::dirname(path), raw_symlink_target));
             if (error_or_path.is_error())
                 return s_symlink_icon;
 
diff --git a/Userland/Libraries/LibGUI/FileIconProvider.h b/Userland/Libraries/LibGUI/FileIconProvider.h
index 4807e0cd24b..1c77047c9ca 100644
--- a/Userland/Libraries/LibGUI/FileIconProvider.h
+++ b/Userland/Libraries/LibGUI/FileIconProvider.h
@@ -16,7 +16,7 @@ class FileIconProvider {
 public:
     static Icon icon_for_path(StringView, mode_t);
     static Icon icon_for_path(StringView);
-    static Icon icon_for_executable(DeprecatedString const&);
+    static Icon icon_for_executable(ByteString const&);
 
     static Icon filetype_image_icon();
     static Icon directory_icon();
diff --git a/Userland/Libraries/LibGUI/FilePicker.cpp b/Userland/Libraries/LibGUI/FilePicker.cpp
index 999024e3413..13441156e9a 100644
--- a/Userland/Libraries/LibGUI/FilePicker.cpp
+++ b/Userland/Libraries/LibGUI/FilePicker.cpp
@@ -48,7 +48,7 @@ ErrorOr<Optional<String>> FilePicker::get_filepath(Badge<FileSystemAccessServer:
     ConnectionToWindowServer::the().set_window_parent_from_client(window_server_client_id, parent_window_id, picker->window_id());
 
     if (picker->exec() == ExecResult::OK) {
-        auto file_path = TRY(picker->selected_file().map([](auto& v) { return String::from_deprecated_string(v); }));
+        auto file_path = TRY(picker->selected_file().map([](auto& v) { return String::from_byte_string(v); }));
         if (file_path.has_value() && file_path->is_empty())
             return Optional<String> {};
 
@@ -57,7 +57,7 @@ ErrorOr<Optional<String>> FilePicker::get_filepath(Badge<FileSystemAccessServer:
     return Optional<String> {};
 }
 
-Optional<DeprecatedString> FilePicker::get_open_filepath(Window* parent_window, DeprecatedString const& window_title, StringView path, bool folder, ScreenPosition screen_position, Optional<Vector<FileTypeFilter>> allowed_file_types)
+Optional<ByteString> FilePicker::get_open_filepath(Window* parent_window, ByteString const& window_title, StringView path, bool folder, ScreenPosition screen_position, Optional<Vector<FileTypeFilter>> allowed_file_types)
 {
     auto picker = FilePicker::construct(parent_window, folder ? Mode::OpenFolder : Mode::Open, ""sv, path, screen_position, move(allowed_file_types));
 
@@ -70,9 +70,9 @@ Optional<DeprecatedString> FilePicker::get_open_filepath(Window* parent_window,
     return {};
 }
 
-Optional<DeprecatedString> FilePicker::get_save_filepath(Window* parent_window, DeprecatedString const& title, DeprecatedString const& extension, StringView path, ScreenPosition screen_position)
+Optional<ByteString> FilePicker::get_save_filepath(Window* parent_window, ByteString const& title, ByteString const& extension, StringView path, ScreenPosition screen_position)
 {
-    auto picker = FilePicker::construct(parent_window, Mode::Save, DeprecatedString::formatted("{}.{}", title, extension), path, screen_position);
+    auto picker = FilePicker::construct(parent_window, Mode::Save, ByteString::formatted("{}.{}", title, extension), path, screen_position);
 
     if (picker->exec() == ExecResult::OK)
         return picker->selected_file();
@@ -138,11 +138,11 @@ FilePicker::FilePicker(Window* parent_window, Mode mode, StringView filename, St
 
             StringBuilder extension_list;
             extension_list.join("; "sv, *filter.extensions);
-            m_allowed_file_types_names.append(DeprecatedString::formatted("{} ({})", filter.name, extension_list.to_deprecated_string()));
+            m_allowed_file_types_names.append(ByteString::formatted("{} ({})", filter.name, extension_list.to_byte_string()));
         }
 
-        file_types_filters_combo->set_model(*GUI::ItemListModel<DeprecatedString, Vector<DeprecatedString>>::create(m_allowed_file_types_names));
-        file_types_filters_combo->on_change = [this](DeprecatedString const&, GUI::ModelIndex const& index) {
+        file_types_filters_combo->set_model(*GUI::ItemListModel<ByteString, Vector<ByteString>>::create(m_allowed_file_types_names));
+        file_types_filters_combo->on_change = [this](ByteString const&, GUI::ModelIndex const& index) {
             m_model->set_allowed_file_extensions((*m_allowed_file_types)[index.row()].extensions);
         };
         file_types_filters_combo->set_selected_index(0);
@@ -160,7 +160,7 @@ FilePicker::FilePicker(Window* parent_window, Mode mode, StringView filename, St
 
     auto open_parent_directory_action = Action::create(
         "Open Parent Directory", { Mod_Alt, Key_Up }, Gfx::Bitmap::load_from_file("/res/icons/16x16/open-parent-directory.png"sv).release_value_but_fixme_should_propagate_errors(), [this](Action const&) {
-            set_path(DeprecatedString::formatted("{}/..", m_model->root_path()));
+            set_path(ByteString::formatted("{}/..", m_model->root_path()));
         },
         this);
     toolbar.add_action(*open_parent_directory_action);
@@ -176,10 +176,10 @@ FilePicker::FilePicker(Window* parent_window, Mode mode, StringView filename, St
         "New Directory...", { Mod_Ctrl | Mod_Shift, Key_N }, Gfx::Bitmap::load_from_file("/res/icons/16x16/mkdir.png"sv).release_value_but_fixme_should_propagate_errors(), [this](Action const&) {
             String value;
             if (InputBox::show(this, value, "Enter a name:"sv, "New Directory"sv, GUI::InputType::NonemptyText) == InputBox::ExecResult::OK) {
-                auto new_dir_path = LexicalPath::canonicalized_path(DeprecatedString::formatted("{}/{}", m_model->root_path(), value));
+                auto new_dir_path = LexicalPath::canonicalized_path(ByteString::formatted("{}/{}", m_model->root_path(), value));
                 int rc = mkdir(new_dir_path.characters(), 0777);
                 if (rc < 0) {
-                    (void)MessageBox::try_show_error(this, DeprecatedString::formatted("Making new directory \"{}\" failed: {}", new_dir_path, Error::from_errno(errno)));
+                    (void)MessageBox::try_show_error(this, ByteString::formatted("Making new directory \"{}\" failed: {}", new_dir_path, Error::from_errno(errno)));
                 } else {
                     m_model->invalidate();
                 }
@@ -304,7 +304,7 @@ FilePicker::FilePicker(Window* parent_window, Mode mode, StringView filename, St
         m_view->view_as_columns_action().set_enabled(true);
     };
 
-    common_locations_tray.on_item_activation = [this](DeprecatedString const& path) {
+    common_locations_tray.on_item_activation = [this](ByteString const& path) {
         set_path(path);
     };
     for (auto& location : CommonLocationsProvider::common_locations()) {
@@ -336,7 +336,7 @@ void FilePicker::on_file_return()
     bool file_exists = !stat_or_error.is_error();
 
     if (!file_exists && (m_mode == Mode::Open || m_mode == Mode::OpenFolder)) {
-        (void)MessageBox::try_show_error(this, DeprecatedString::formatted("Opening \"{}\" failed: {}", m_filename_textbox->text(), Error::from_errno(ENOENT)));
+        (void)MessageBox::try_show_error(this, ByteString::formatted("Opening \"{}\" failed: {}", m_filename_textbox->text(), Error::from_errno(ENOENT)));
         return;
     }
 
@@ -360,10 +360,10 @@ void FilePicker::on_file_return()
     done(ExecResult::OK);
 }
 
-void FilePicker::set_path(DeprecatedString const& path)
+void FilePicker::set_path(ByteString const& path)
 {
     if (access(path.characters(), R_OK | X_OK) == -1) {
-        (void)GUI::MessageBox::try_show_error(this, DeprecatedString::formatted("Opening \"{}\" failed: {}", path, Error::from_errno(errno)));
+        (void)GUI::MessageBox::try_show_error(this, ByteString::formatted("Opening \"{}\" failed: {}", path, Error::from_errno(errno)));
         auto& common_locations_tray = *find_descendant_of_type_named<GUI::Tray>("common_locations_tray");
         for (auto& location_button : m_common_location_buttons)
             common_locations_tray.set_item_checked(location_button.tray_item_index, m_model->root_path() == location_button.path);
diff --git a/Userland/Libraries/LibGUI/FilePicker.h b/Userland/Libraries/LibGUI/FilePicker.h
index bef85a2c9bf..ae3dd86ea76 100644
--- a/Userland/Libraries/LibGUI/FilePicker.h
+++ b/Userland/Libraries/LibGUI/FilePicker.h
@@ -37,19 +37,19 @@ public:
         Save
     };
 
-    static Optional<DeprecatedString> get_open_filepath(Window* parent_window, DeprecatedString const& window_title = {}, StringView path = Core::StandardPaths::home_directory(), bool folder = false, ScreenPosition screen_position = Dialog::ScreenPosition::CenterWithinParent, Optional<Vector<FileTypeFilter>> allowed_file_types = {});
-    static Optional<DeprecatedString> get_save_filepath(Window* parent_window, DeprecatedString const& title, DeprecatedString const& extension, StringView path = Core::StandardPaths::home_directory(), ScreenPosition screen_position = Dialog::ScreenPosition::CenterWithinParent);
+    static Optional<ByteString> get_open_filepath(Window* parent_window, ByteString const& window_title = {}, StringView path = Core::StandardPaths::home_directory(), bool folder = false, ScreenPosition screen_position = Dialog::ScreenPosition::CenterWithinParent, Optional<Vector<FileTypeFilter>> allowed_file_types = {});
+    static Optional<ByteString> get_save_filepath(Window* parent_window, ByteString const& title, ByteString const& extension, StringView path = Core::StandardPaths::home_directory(), ScreenPosition screen_position = Dialog::ScreenPosition::CenterWithinParent);
 
     static ErrorOr<Optional<String>> get_filepath(Badge<FileSystemAccessServer::ConnectionFromClient>, i32 window_server_client_id, i32 parent_window_id, Mode, StringView window_title, StringView file_basename = {}, StringView path = Core::StandardPaths::home_directory(), Optional<Vector<FileTypeFilter>> = {});
 
     virtual ~FilePicker() override;
 
-    Optional<DeprecatedString> const& selected_file() const { return m_selected_file; }
+    Optional<ByteString> const& selected_file() const { return m_selected_file; }
 
 private:
     void on_file_return();
 
-    void set_path(DeprecatedString const&);
+    void set_path(ByteString const&);
 
     // ^GUI::ModelClient
     virtual void model_did_update(unsigned) override;
@@ -71,15 +71,15 @@ private:
     }
 
     struct CommonLocationButton {
-        DeprecatedString path;
+        ByteString path;
         size_t tray_item_index { 0 };
     };
 
     RefPtr<MultiView> m_view;
     NonnullRefPtr<FileSystemModel> m_model;
-    Optional<DeprecatedString> m_selected_file;
+    Optional<ByteString> m_selected_file;
 
-    Vector<DeprecatedString> m_allowed_file_types_names;
+    Vector<ByteString> m_allowed_file_types_names;
     Optional<Vector<FileTypeFilter>> m_allowed_file_types;
 
     RefPtr<GUI::Label> m_error_label;
diff --git a/Userland/Libraries/LibGUI/FileSystemModel.cpp b/Userland/Libraries/LibGUI/FileSystemModel.cpp
index 8fb24554959..8aaae5a8472 100644
--- a/Userland/Libraries/LibGUI/FileSystemModel.cpp
+++ b/Userland/Libraries/LibGUI/FileSystemModel.cpp
@@ -41,7 +41,7 @@ ModelIndex FileSystemModel::Node::index(int column) const
     VERIFY_NOT_REACHED();
 }
 
-bool FileSystemModel::Node::fetch_data(DeprecatedString const& full_path, bool is_root)
+bool FileSystemModel::Node::fetch_data(ByteString const& full_path, bool is_root)
 {
     struct stat st;
     int rc;
@@ -67,7 +67,7 @@ bool FileSystemModel::Node::fetch_data(DeprecatedString const& full_path, bool i
         if (sym_link_target_or_error.is_error())
             perror("readlink");
         else {
-            symlink_target = sym_link_target_or_error.release_value().to_deprecated_string();
+            symlink_target = sym_link_target_or_error.release_value().to_byte_string();
             if (symlink_target.is_empty())
                 perror("readlink");
         }
@@ -122,7 +122,7 @@ void FileSystemModel::Node::traverse_if_needed()
         return;
     }
 
-    Vector<DeprecatedString> child_names;
+    Vector<ByteString> child_names;
     while (di.has_next()) {
         child_names.append(di.next_path());
     }
@@ -147,7 +147,7 @@ void FileSystemModel::Node::traverse_if_needed()
             }
 
             for (auto& extension : *m_model.m_allowed_file_extensions) {
-                if (child_name.ends_with(DeprecatedString::formatted(".{}", extension))) {
+                if (child_name.ends_with(ByteString::formatted(".{}", extension))) {
                     file_children.append(move(child));
                     break;
                 }
@@ -181,9 +181,9 @@ bool FileSystemModel::Node::can_delete_or_move() const
     return m_can_delete_or_move.value();
 }
 
-OwnPtr<FileSystemModel::Node> FileSystemModel::Node::create_child(DeprecatedString const& child_name)
+OwnPtr<FileSystemModel::Node> FileSystemModel::Node::create_child(ByteString const& child_name)
 {
-    DeprecatedString child_path = LexicalPath::join(full_path(), child_name).string();
+    ByteString child_path = LexicalPath::join(full_path(), child_name).string();
     auto child = adopt_own(*new Node(m_model));
 
     bool ok = child->fetch_data(child_path, false);
@@ -215,9 +215,9 @@ bool FileSystemModel::Node::is_symlink_to_directory() const
     return S_ISDIR(st.st_mode);
 }
 
-DeprecatedString FileSystemModel::Node::full_path() const
+ByteString FileSystemModel::Node::full_path() const
 {
-    Vector<DeprecatedString, 32> lineage;
+    Vector<ByteString, 32> lineage;
     for (auto* ancestor = m_parent; ancestor; ancestor = ancestor->m_parent) {
         lineage.append(ancestor->name);
     }
@@ -229,10 +229,10 @@ DeprecatedString FileSystemModel::Node::full_path() const
     }
     builder.append('/');
     builder.append(name);
-    return LexicalPath::canonicalized_path(builder.to_deprecated_string());
+    return LexicalPath::canonicalized_path(builder.to_byte_string());
 }
 
-ModelIndex FileSystemModel::index(DeprecatedString path, int column) const
+ModelIndex FileSystemModel::index(ByteString path, int column) const
 {
     auto node = node_for_path(move(path));
     if (node.has_value())
@@ -241,9 +241,9 @@ ModelIndex FileSystemModel::index(DeprecatedString path, int column) const
     return {};
 }
 
-Optional<FileSystemModel::Node const&> FileSystemModel::node_for_path(DeprecatedString const& path) const
+Optional<FileSystemModel::Node const&> FileSystemModel::node_for_path(ByteString const& path) const
 {
-    DeprecatedString resolved_path;
+    ByteString resolved_path;
     if (path == m_root_path)
         resolved_path = "/";
     else if (m_root_path.has_value() && !m_root_path->is_empty() && path.starts_with(*m_root_path))
@@ -276,14 +276,14 @@ Optional<FileSystemModel::Node const&> FileSystemModel::node_for_path(Deprecated
     return {};
 }
 
-DeprecatedString FileSystemModel::full_path(ModelIndex const& index) const
+ByteString FileSystemModel::full_path(ModelIndex const& index) const
 {
     auto& node = this->node(index);
     const_cast<Node&>(node).reify_if_needed();
     return node.full_path();
 }
 
-FileSystemModel::FileSystemModel(Optional<DeprecatedString> root_path, Mode mode)
+FileSystemModel::FileSystemModel(Optional<ByteString> root_path, Mode mode)
     : m_root_path(root_path.map(LexicalPath::canonicalized_path))
     , m_mode(mode)
 {
@@ -311,23 +311,23 @@ FileSystemModel::FileSystemModel(Optional<DeprecatedString> root_path, Mode mode
     invalidate();
 }
 
-DeprecatedString FileSystemModel::name_for_uid(uid_t uid) const
+ByteString FileSystemModel::name_for_uid(uid_t uid) const
 {
     auto it = m_user_names.find(uid);
     if (it == m_user_names.end())
-        return DeprecatedString::number(uid);
+        return ByteString::number(uid);
     return (*it).value;
 }
 
-DeprecatedString FileSystemModel::name_for_gid(gid_t gid) const
+ByteString FileSystemModel::name_for_gid(gid_t gid) const
 {
     auto it = m_group_names.find(gid);
     if (it == m_group_names.end())
-        return DeprecatedString::number(gid);
+        return ByteString::number(gid);
     return (*it).value;
 }
 
-static DeprecatedString permission_string(mode_t mode)
+static ByteString permission_string(mode_t mode)
 {
     StringBuilder builder;
     if (S_ISDIR(mode))
@@ -360,7 +360,7 @@ static DeprecatedString permission_string(mode_t mode)
         builder.append('t');
     else
         builder.append(mode & S_IXOTH ? 'x' : '-');
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 void FileSystemModel::Node::set_selected(bool selected)
@@ -376,7 +376,7 @@ void FileSystemModel::update_node_on_selection(ModelIndex const& index, bool con
     node.set_selected(selected);
 }
 
-void FileSystemModel::set_root_path(Optional<DeprecatedString> root_path)
+void FileSystemModel::set_root_path(Optional<ByteString> root_path)
 {
     if (!root_path.has_value())
         m_root_path = {};
@@ -692,8 +692,8 @@ using BitmapBackgroundAction = Threading::BackgroundAction<NonnullRefPtr<Gfx::Bi
 // Mutex protected thumbnail cache data shared between threads.
 struct ThumbnailCache {
     // Null pointers indicate an image that couldn't be loaded due to errors.
-    HashMap<DeprecatedString, RefPtr<Gfx::Bitmap>> thumbnail_cache {};
-    HashMap<DeprecatedString, NonnullRefPtr<BitmapBackgroundAction>> loading_thumbnails {};
+    HashMap<ByteString, RefPtr<Gfx::Bitmap>> thumbnail_cache {};
+    HashMap<ByteString, NonnullRefPtr<BitmapBackgroundAction>> loading_thumbnails {};
 };
 
 static Threading::MutexProtected<ThumbnailCache> s_thumbnail_cache {};
@@ -853,7 +853,7 @@ void FileSystemModel::set_should_show_dotfiles(bool show)
     invalidate();
 }
 
-void FileSystemModel::set_allowed_file_extensions(Optional<Vector<DeprecatedString>> const& allowed_file_extensions)
+void FileSystemModel::set_allowed_file_extensions(Optional<Vector<ByteString>> const& allowed_file_extensions)
 {
     if (m_allowed_file_extensions == allowed_file_extensions)
         return;
@@ -874,7 +874,7 @@ void FileSystemModel::set_data(ModelIndex const& index, Variant const& data)
     VERIFY(is_editable(index));
     Node& node = const_cast<Node&>(this->node(index));
     auto dirname = LexicalPath::dirname(node.full_path());
-    auto new_full_path = DeprecatedString::formatted("{}/{}", dirname, data.to_deprecated_string());
+    auto new_full_path = ByteString::formatted("{}/{}", dirname, data.to_byte_string());
     int rc = rename(node.full_path().characters(), new_full_path.characters());
     if (rc < 0) {
         if (on_rename_error)
diff --git a/Userland/Libraries/LibGUI/FileSystemModel.h b/Userland/Libraries/LibGUI/FileSystemModel.h
index ee14d668996..53fb64be23c 100644
--- a/Userland/Libraries/LibGUI/FileSystemModel.h
+++ b/Userland/Libraries/LibGUI/FileSystemModel.h
@@ -46,8 +46,8 @@ public:
     struct Node {
         ~Node() = default;
 
-        DeprecatedString name;
-        DeprecatedString symlink_target;
+        ByteString name;
+        ByteString symlink_target;
         size_t size { 0 };
         mode_t mode { 0 };
         uid_t uid { 0 };
@@ -72,7 +72,7 @@ public:
 
         bool can_delete_or_move() const;
 
-        DeprecatedString full_path() const;
+        ByteString full_path() const;
 
     private:
         friend class FileSystemModel;
@@ -97,21 +97,21 @@ public:
         ModelIndex index(int column) const;
         void traverse_if_needed();
         void reify_if_needed();
-        bool fetch_data(DeprecatedString const& full_path, bool is_root);
+        bool fetch_data(ByteString const& full_path, bool is_root);
 
-        OwnPtr<Node> create_child(DeprecatedString const& child_name);
+        OwnPtr<Node> create_child(ByteString const& child_name);
     };
 
-    static NonnullRefPtr<FileSystemModel> create(Optional<DeprecatedString> root_path = "/", Mode mode = Mode::FilesAndDirectories)
+    static NonnullRefPtr<FileSystemModel> create(Optional<ByteString> root_path = "/", Mode mode = Mode::FilesAndDirectories)
     {
         return adopt_ref(*new FileSystemModel(root_path, mode));
     }
     virtual ~FileSystemModel() override = default;
 
-    DeprecatedString root_path() const { return m_root_path.value_or(""); }
-    void set_root_path(Optional<DeprecatedString>);
-    DeprecatedString full_path(ModelIndex const&) const;
-    ModelIndex index(DeprecatedString path, int column) const;
+    ByteString root_path() const { return m_root_path.value_or(""); }
+    void set_root_path(Optional<ByteString>);
+    ByteString full_path(ModelIndex const&) const;
+    ModelIndex index(ByteString path, int column) const;
 
     void update_node_on_selection(ModelIndex const&, bool const);
     ModelIndex m_previously_selected_index {};
@@ -122,7 +122,7 @@ public:
     Function<void()> on_complete;
     Function<void(int error, char const* error_string)> on_directory_change_error;
     Function<void(int error, char const* error_string)> on_rename_error;
-    Function<void(DeprecatedString const& old_name, DeprecatedString const& new_name)> on_rename_successful;
+    Function<void(ByteString const& old_name, ByteString const& new_name)> on_rename_successful;
     Function<void()> on_root_path_removed;
 
     virtual int tree_column() const override { return Column::Name; }
@@ -141,34 +141,34 @@ public:
     virtual Vector<ModelIndex> matches(StringView, unsigned = MatchesFlag::AllMatching, ModelIndex const& = ModelIndex()) override;
     virtual void invalidate() override;
 
-    static DeprecatedString timestamp_string(time_t timestamp)
+    static ByteString timestamp_string(time_t timestamp)
     {
-        return Core::DateTime::from_timestamp(timestamp).to_deprecated_string();
+        return Core::DateTime::from_timestamp(timestamp).to_byte_string();
     }
 
     bool should_show_dotfiles() const { return m_should_show_dotfiles; }
     void set_should_show_dotfiles(bool);
 
-    Optional<Vector<DeprecatedString>> allowed_file_extensions() const { return m_allowed_file_extensions; }
-    void set_allowed_file_extensions(Optional<Vector<DeprecatedString>> const& allowed_file_extensions);
+    Optional<Vector<ByteString>> allowed_file_extensions() const { return m_allowed_file_extensions; }
+    void set_allowed_file_extensions(Optional<Vector<ByteString>> const& allowed_file_extensions);
 
 private:
-    FileSystemModel(Optional<DeprecatedString> root_path, Mode);
+    FileSystemModel(Optional<ByteString> root_path, Mode);
 
-    DeprecatedString name_for_uid(uid_t) const;
-    DeprecatedString name_for_gid(gid_t) const;
+    ByteString name_for_uid(uid_t) const;
+    ByteString name_for_gid(gid_t) const;
 
-    Optional<Node const&> node_for_path(DeprecatedString const&) const;
+    Optional<Node const&> node_for_path(ByteString const&) const;
 
-    HashMap<uid_t, DeprecatedString> m_user_names;
-    HashMap<gid_t, DeprecatedString> m_group_names;
+    HashMap<uid_t, ByteString> m_user_names;
+    HashMap<gid_t, ByteString> m_group_names;
 
     bool fetch_thumbnail_for(Node const& node);
     GUI::Icon icon_for(Node const& node) const;
 
     void handle_file_event(Core::FileWatcherEvent const& event);
 
-    Optional<DeprecatedString> m_root_path;
+    Optional<ByteString> m_root_path;
     Mode m_mode { Invalid };
     OwnPtr<Node> m_root { nullptr };
 
@@ -177,7 +177,7 @@ private:
 
     Core::ElapsedTimer m_ui_update_timer;
 
-    Optional<Vector<DeprecatedString>> m_allowed_file_extensions;
+    Optional<Vector<ByteString>> m_allowed_file_extensions;
 
     bool m_should_show_dotfiles { false };
 
diff --git a/Userland/Libraries/LibGUI/FileTypeFilter.h b/Userland/Libraries/LibGUI/FileTypeFilter.h
index 98bc4e93306..7cd07f802b7 100644
--- a/Userland/Libraries/LibGUI/FileTypeFilter.h
+++ b/Userland/Libraries/LibGUI/FileTypeFilter.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <AK/Vector.h>
 #include <LibIPC/Decoder.h>
@@ -15,8 +15,8 @@
 namespace GUI {
 
 struct FileTypeFilter {
-    DeprecatedString name;
-    Optional<Vector<DeprecatedString>> extensions;
+    ByteString name;
+    Optional<Vector<ByteString>> extensions;
 
     static FileTypeFilter all_files()
     {
@@ -25,7 +25,7 @@ struct FileTypeFilter {
 
     static FileTypeFilter image_files()
     {
-        return FileTypeFilter { "Image Files", Vector<DeprecatedString> { "png", "gif", "bmp", "dip", "pbm", "pgm", "ppm", "ico", "iff", "jpeg", "jpg", "jxl", "dds", "qoi", "tif", "tiff", "webp", "tvg" } };
+        return FileTypeFilter { "Image Files", Vector<ByteString> { "png", "gif", "bmp", "dip", "pbm", "pgm", "ppm", "ico", "iff", "jpeg", "jpg", "jxl", "dds", "qoi", "tif", "tiff", "webp", "tvg" } };
     }
 };
 
@@ -44,8 +44,8 @@ inline ErrorOr<void> encode(Encoder& encoder, GUI::FileTypeFilter const& respons
 template<>
 inline ErrorOr<GUI::FileTypeFilter> decode(Decoder& decoder)
 {
-    auto name = TRY(decoder.decode<DeprecatedString>());
-    auto extensions = TRY(decoder.decode<Optional<Vector<AK::DeprecatedString>>>());
+    auto name = TRY(decoder.decode<ByteString>());
+    auto extensions = TRY(decoder.decode<Optional<Vector<AK::ByteString>>>());
 
     return GUI::FileTypeFilter { move(name), move(extensions) };
 }
diff --git a/Userland/Libraries/LibGUI/FilteringProxyModel.h b/Userland/Libraries/LibGUI/FilteringProxyModel.h
index 032e226177b..25ad50ffd32 100644
--- a/Userland/Libraries/LibGUI/FilteringProxyModel.h
+++ b/Userland/Libraries/LibGUI/FilteringProxyModel.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/EnumBits.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/Optional.h>
@@ -68,7 +68,7 @@ private:
     // Maps row to actual model index.
     Vector<ModelIndexWithScore> m_matching_indices;
 
-    DeprecatedString m_filter_term;
+    ByteString m_filter_term;
     FilteringOptions m_filtering_options;
 };
 
diff --git a/Userland/Libraries/LibGUI/FontPicker.cpp b/Userland/Libraries/LibGUI/FontPicker.cpp
index c78d1dc9bc3..0f64654724e 100644
--- a/Userland/Libraries/LibGUI/FontPicker.cpp
+++ b/Userland/Libraries/LibGUI/FontPicker.cpp
@@ -57,7 +57,7 @@ FontPicker::FontPicker(Window* parent_window, Gfx::Font const* current_font, boo
 
     m_family_list_view->on_selection_change = [this] {
         const auto& index = m_family_list_view->selection().first();
-        m_family = MUST(String::from_deprecated_string(index.data().to_deprecated_string()));
+        m_family = MUST(String::from_byte_string(index.data().to_byte_string()));
         m_variants.clear();
         Gfx::FontDatabase::the().for_each_typeface([&](auto& typeface) {
             if (m_fixed_width_only && !typeface.is_fixed_width())
@@ -78,7 +78,7 @@ FontPicker::FontPicker(Window* parent_window, Gfx::Font const* current_font, boo
     m_variant_list_view->on_selection_change = [this] {
         const auto& index = m_variant_list_view->selection().first();
         bool font_is_fixed_size = false;
-        m_variant = MUST(String::from_deprecated_string(index.data().to_deprecated_string()));
+        m_variant = MUST(String::from_byte_string(index.data().to_byte_string()));
         m_sizes.clear();
         Gfx::FontDatabase::the().for_each_typeface([&](auto& typeface) {
             if (m_fixed_width_only && !typeface.is_fixed_width())
diff --git a/Userland/Libraries/LibGUI/GML/AST.h b/Userland/Libraries/LibGUI/GML/AST.h
index 7e62947116b..90dd0405b7c 100644
--- a/Userland/Libraries/LibGUI/GML/AST.h
+++ b/Userland/Libraries/LibGUI/GML/AST.h
@@ -6,8 +6,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/Concepts.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Error.h>
 #include <AK/Forward.h>
 #include <AK/HashMap.h>
@@ -35,11 +35,11 @@ public:
         return try_make_ref_counted<NodeT>(token.m_view);
     }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
         StringBuilder builder;
         format(builder, 0, false);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 
     // Format this AST node with the builder at the given indentation level.
@@ -64,7 +64,7 @@ public:
 // Single line comments with //.
 class Comment : public Node {
 public:
-    Comment(DeprecatedString text)
+    Comment(ByteString text)
         : m_text(move(text))
     {
     }
@@ -82,13 +82,13 @@ public:
     virtual ~Comment() override = default;
 
 private:
-    DeprecatedString m_text {};
+    ByteString m_text {};
 };
 
 // Any JSON-like key: value pair.
 class KeyValuePair : public Node {
 public:
-    KeyValuePair(DeprecatedString key, NonnullRefPtr<ValueNode> value)
+    KeyValuePair(ByteString key, NonnullRefPtr<ValueNode> value)
         : m_key(move(key))
         , m_value(move(value))
     {
@@ -104,11 +104,11 @@ public:
             builder.append('\n');
     }
 
-    DeprecatedString key() const { return m_key; }
+    ByteString key() const { return m_key; }
     NonnullRefPtr<ValueNode> value() const { return m_value; }
 
 private:
-    DeprecatedString m_key;
+    ByteString m_key;
     NonnullRefPtr<ValueNode> m_value;
 };
 
@@ -151,7 +151,7 @@ public:
 class Object : public ValueNode {
 public:
     Object() = default;
-    Object(DeprecatedString name, Vector<NonnullRefPtr<Node const>> properties, Vector<NonnullRefPtr<Node const>> sub_objects)
+    Object(ByteString name, Vector<NonnullRefPtr<Node const>> properties, Vector<NonnullRefPtr<Node const>> sub_objects)
         : m_properties(move(properties))
         , m_sub_objects(move(sub_objects))
         , m_name(move(name))
@@ -161,7 +161,7 @@ public:
     virtual ~Object() override = default;
 
     StringView name() const { return m_name; }
-    void set_name(DeprecatedString name) { m_name = move(name); }
+    void set_name(ByteString name) { m_name = move(name); }
 
     ErrorOr<void> add_sub_object_child(NonnullRefPtr<Node const> child)
     {
@@ -289,7 +289,7 @@ private:
     Vector<NonnullRefPtr<Node const>> m_properties;
     // Sub objects and comments
     Vector<NonnullRefPtr<Node const>> m_sub_objects;
-    DeprecatedString m_name {};
+    ByteString m_name {};
 };
 
 class GMLFile : public Node {
diff --git a/Userland/Libraries/LibGUI/GML/AutocompleteProvider.cpp b/Userland/Libraries/LibGUI/GML/AutocompleteProvider.cpp
index 4115fad0fe6..1081b4aba3b 100644
--- a/Userland/Libraries/LibGUI/GML/AutocompleteProvider.cpp
+++ b/Userland/Libraries/LibGUI/GML/AutocompleteProvider.cpp
@@ -25,8 +25,8 @@ void AutocompleteProvider::provide_completions(Function<void(Vector<CodeComprehe
         InIdentifier,
         AfterIdentifier, // Can we introspect this?
     } state { Free };
-    DeprecatedString identifier_string;
-    Vector<DeprecatedString> class_names;
+    ByteString identifier_string;
+    Vector<ByteString> class_names;
     Vector<State> previous_states;
     bool should_push_state { true };
     Token* last_seen_token { nullptr };
@@ -118,26 +118,26 @@ void AutocompleteProvider::provide_completions(Function<void(Vector<CodeComprehe
             fuzzy_str_builder.append(character);
             fuzzy_str_builder.append('*');
         }
-        return fuzzy_str_builder.to_deprecated_string();
+        return fuzzy_str_builder.to_byte_string();
     };
 
     Vector<CodeComprehension::AutocompleteResultEntry> class_entries, identifier_entries;
 
-    auto register_layouts_matching_pattern = [&](DeprecatedString pattern, size_t partial_input_length) {
+    auto register_layouts_matching_pattern = [&](ByteString pattern, size_t partial_input_length) {
         GUI::ObjectClassRegistration::for_each([&](const GUI::ObjectClassRegistration& registration) {
             if (registration.is_derived_from(layout_class) && &registration != &layout_class && registration.class_name().matches(pattern))
-                class_entries.empend(DeprecatedString::formatted("@{}", registration.class_name()), partial_input_length);
+                class_entries.empend(ByteString::formatted("@{}", registration.class_name()), partial_input_length);
         });
     };
 
-    auto register_widgets_matching_pattern = [&](DeprecatedString pattern, size_t partial_input_length) {
+    auto register_widgets_matching_pattern = [&](ByteString pattern, size_t partial_input_length) {
         GUI::ObjectClassRegistration::for_each([&](const GUI::ObjectClassRegistration& registration) {
             if (registration.is_derived_from(widget_class) && registration.class_name().matches(pattern))
-                class_entries.empend(DeprecatedString::formatted("@{}", registration.class_name()), partial_input_length);
+                class_entries.empend(ByteString::formatted("@{}", registration.class_name()), partial_input_length);
         });
     };
 
-    auto register_class_properties_matching_pattern = [&](DeprecatedString pattern, size_t partial_input_length) {
+    auto register_class_properties_matching_pattern = [&](ByteString pattern, size_t partial_input_length) {
         auto class_name = class_names.last();
 
         // FIXME: Don't show properties that are already specified in the scope.
@@ -146,7 +146,7 @@ void AutocompleteProvider::provide_completions(Function<void(Vector<CodeComprehe
             if (auto instance = registration->construct(); !instance.is_error()) {
                 for (auto& it : instance.value()->properties()) {
                     if (!it.value->is_readonly() && it.key.matches(pattern))
-                        identifier_entries.empend(DeprecatedString::formatted("{}: ", it.key), partial_input_length, CodeComprehension::Language::Unspecified, it.key);
+                        identifier_entries.empend(ByteString::formatted("{}: ", it.key), partial_input_length, CodeComprehension::Language::Unspecified, it.key);
                 }
             }
         }
@@ -157,7 +157,7 @@ void AutocompleteProvider::provide_completions(Function<void(Vector<CodeComprehe
             identifier_entries.empend("content_widget: ", partial_input_length, CodeComprehension::Language::Unspecified, "content_widget", CodeComprehension::AutocompleteResultEntry::HideAutocompleteAfterApplying::No);
     };
 
-    auto register_properties_and_widgets_matching_pattern = [&](DeprecatedString pattern, size_t partial_input_length) {
+    auto register_properties_and_widgets_matching_pattern = [&](ByteString pattern, size_t partial_input_length) {
         if (!class_names.is_empty()) {
             register_class_properties_matching_pattern(pattern, partial_input_length);
 
diff --git a/Userland/Libraries/LibGUI/GML/Formatter.h b/Userland/Libraries/LibGUI/GML/Formatter.h
index beb3123d0c5..a8536c6a043 100644
--- a/Userland/Libraries/LibGUI/GML/Formatter.h
+++ b/Userland/Libraries/LibGUI/GML/Formatter.h
@@ -6,16 +6,16 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <LibGUI/GML/AST.h>
 #include <LibGUI/GML/Parser.h>
 
 namespace GUI::GML {
 
-inline ErrorOr<DeprecatedString> format_gml(StringView string)
+inline ErrorOr<ByteString> format_gml(StringView string)
 {
-    return TRY(parse_gml(string))->to_deprecated_string();
+    return TRY(parse_gml(string))->to_byte_string();
 }
 
 }
diff --git a/Userland/Libraries/LibGUI/GroupBox.h b/Userland/Libraries/LibGUI/GroupBox.h
index 948144e17f8..85be54c1652 100644
--- a/Userland/Libraries/LibGUI/GroupBox.h
+++ b/Userland/Libraries/LibGUI/GroupBox.h
@@ -16,7 +16,7 @@ class GroupBox : public Widget {
 public:
     virtual ~GroupBox() override = default;
 
-    DeprecatedString title() const { return m_title; }
+    ByteString title() const { return m_title; }
     void set_title(StringView);
     virtual Margins content_margins() const override;
 
@@ -27,7 +27,7 @@ protected:
     virtual void fonts_change_event(FontsChangeEvent&) override;
 
 private:
-    DeprecatedString m_title;
+    ByteString m_title;
 };
 
 }
diff --git a/Userland/Libraries/LibGUI/HeaderView.cpp b/Userland/Libraries/LibGUI/HeaderView.cpp
index c6ff384136f..e59f3110a8a 100644
--- a/Userland/Libraries/LibGUI/HeaderView.cpp
+++ b/Userland/Libraries/LibGUI/HeaderView.cpp
@@ -304,7 +304,7 @@ void HeaderView::paint_vertical(Painter& painter)
         bool pressed = section == m_pressed_section && m_pressed_section_is_pressed;
         bool hovered = false;
         Gfx::StylePainter::paint_button(painter, cell_rect, palette(), Gfx::ButtonStyle::Normal, pressed, hovered);
-        DeprecatedString text = DeprecatedString::number(section);
+        ByteString text = ByteString::number(section);
         auto text_rect = cell_rect.shrunken(m_table_view.horizontal_padding() * 2, 0);
         if (pressed)
             text_rect.translate_by(1, 1);
@@ -358,7 +358,7 @@ Menu& HeaderView::ensure_context_menu()
         int section_count = this->section_count();
         for (int section = 0; section < section_count; ++section) {
             auto& column_data = this->section_data(section);
-            auto name = model()->column_name(section).release_value_but_fixme_should_propagate_errors().to_deprecated_string();
+            auto name = model()->column_name(section).release_value_but_fixme_should_propagate_errors().to_byte_string();
             column_data.visibility_action = Action::create_checkable(name, [this, section](auto& action) {
                 set_section_visible(section, action.is_checked());
             });
diff --git a/Userland/Libraries/LibGUI/Icon.cpp b/Userland/Libraries/LibGUI/Icon.cpp
index e2a8c6637aa..513558ce4a7 100644
--- a/Userland/Libraries/LibGUI/Icon.cpp
+++ b/Userland/Libraries/LibGUI/Icon.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibGUI/Icon.h>
 #include <LibGfx/Bitmap.h>
 
@@ -82,9 +82,9 @@ ErrorOr<Icon> Icon::try_create_default_icon(StringView name)
 {
     RefPtr<Gfx::Bitmap> bitmap16;
     RefPtr<Gfx::Bitmap> bitmap32;
-    if (auto bitmap_or_error = Gfx::Bitmap::load_from_file(DeprecatedString::formatted("/res/icons/16x16/{}.png", name)); !bitmap_or_error.is_error())
+    if (auto bitmap_or_error = Gfx::Bitmap::load_from_file(ByteString::formatted("/res/icons/16x16/{}.png", name)); !bitmap_or_error.is_error())
         bitmap16 = bitmap_or_error.release_value();
-    if (auto bitmap_or_error = Gfx::Bitmap::load_from_file(DeprecatedString::formatted("/res/icons/32x32/{}.png", name)); !bitmap_or_error.is_error())
+    if (auto bitmap_or_error = Gfx::Bitmap::load_from_file(ByteString::formatted("/res/icons/32x32/{}.png", name)); !bitmap_or_error.is_error())
         bitmap32 = bitmap_or_error.release_value();
 
     if (!bitmap16 && !bitmap32) {
diff --git a/Userland/Libraries/LibGUI/IconView.cpp b/Userland/Libraries/LibGUI/IconView.cpp
index 1bbab12977f..115070602da 100644
--- a/Userland/Libraries/LibGUI/IconView.cpp
+++ b/Userland/Libraries/LibGUI/IconView.cpp
@@ -106,7 +106,7 @@ auto IconView::get_item_data(int item_index) const -> ItemData&
         return item_data;
 
     item_data.index = model()->index(item_index, model_column());
-    item_data.text = item_data.index.data().to_deprecated_string();
+    item_data.text = item_data.index.data().to_byte_string();
     get_item_rects(item_index, item_data, font_for_index(item_data.index));
     item_data.valid = true;
     return item_data;
diff --git a/Userland/Libraries/LibGUI/IconView.h b/Userland/Libraries/LibGUI/IconView.h
index 9f68d2126fa..42e072dc36d 100644
--- a/Userland/Libraries/LibGUI/IconView.h
+++ b/Userland/Libraries/LibGUI/IconView.h
@@ -73,7 +73,7 @@ private:
         Gfx::IntRect icon_rect;
         int icon_offset_y;
         int text_offset_y;
-        DeprecatedString text;
+        ByteString text;
         Vector<StringView> wrapped_text_lines;
         ModelIndex index;
         bool valid { false };
diff --git a/Userland/Libraries/LibGUI/InputBox.cpp b/Userland/Libraries/LibGUI/InputBox.cpp
index a6869603a65..94034ea3984 100644
--- a/Userland/Libraries/LibGUI/InputBox.cpp
+++ b/Userland/Libraries/LibGUI/InputBox.cpp
@@ -42,7 +42,7 @@ InputBox::InputBox(Window* parent_window, String text_value, String title, Strin
     , m_input_type(input_type)
     , m_icon(move(icon))
 {
-    set_title(move(title).to_deprecated_string());
+    set_title(move(title).to_byte_string());
     set_resizable(false);
     set_auto_shrink(true);
 }
@@ -54,7 +54,7 @@ InputBox::InputBox(Window* parent_window, int value, String title, String prompt
     , m_input_type(InputType::Numeric)
     , m_icon(move(icon))
 {
-    set_title(move(title).to_deprecated_string());
+    set_title(move(title).to_byte_string());
     set_resizable(false);
     set_auto_shrink(true);
 }
@@ -119,7 +119,7 @@ void InputBox::on_done(ExecResult result)
         return;
 
     if (m_text_editor) {
-        auto value = String::from_deprecated_string(m_text_editor->text());
+        auto value = String::from_byte_string(m_text_editor->text());
         if (!value.is_error())
             m_text_value = value.release_value();
     } else if (m_spinbox)
diff --git a/Userland/Libraries/LibGUI/ItemListModel.h b/Userland/Libraries/LibGUI/ItemListModel.h
index 9d7ef265602..b9a7504b601 100644
--- a/Userland/Libraries/LibGUI/ItemListModel.h
+++ b/Userland/Libraries/LibGUI/ItemListModel.h
@@ -96,7 +96,7 @@ public:
             for (auto it = m_data.begin(); it != m_data.end(); ++it) {
                 for (auto it2d = (*it).begin(); it2d != (*it).end(); ++it2d) {
                     GUI::ModelIndex index = this->index(it.index(), it2d.index());
-                    if (!string_matches(data(index, ModelRole::Display).to_deprecated_string(), searching, flags))
+                    if (!string_matches(data(index, ModelRole::Display).to_byte_string(), searching, flags))
                         continue;
 
                     found_indices.append(index);
@@ -107,7 +107,7 @@ public:
         } else {
             for (auto it = m_data.begin(); it != m_data.end(); ++it) {
                 GUI::ModelIndex index = this->index(it.index());
-                if (!string_matches(data(index, ModelRole::Display).to_deprecated_string(), searching, flags))
+                if (!string_matches(data(index, ModelRole::Display).to_byte_string(), searching, flags))
                     continue;
 
                 found_indices.append(index);
diff --git a/Userland/Libraries/LibGUI/JsonArrayModel.cpp b/Userland/Libraries/LibGUI/JsonArrayModel.cpp
index c1a5e349328..66b3463519a 100644
--- a/Userland/Libraries/LibGUI/JsonArrayModel.cpp
+++ b/Userland/Libraries/LibGUI/JsonArrayModel.cpp
@@ -61,7 +61,7 @@ void JsonArrayModel::update()
 ErrorOr<void> JsonArrayModel::store()
 {
     auto file = TRY(Core::File::open(m_json_path, Core::File::OpenMode::Write));
-    ByteBuffer json_bytes = m_array.to_deprecated_string().to_byte_buffer();
+    ByteBuffer json_bytes = m_array.to_byte_string().to_byte_buffer();
 
     TRY(file->write_until_depleted(json_bytes));
     file->close();
@@ -138,7 +138,7 @@ Variant JsonArrayModel::data(ModelIndex const& index, ModelRole role) const
             return "";
         if (data->is_number())
             return data.value();
-        return data->to_deprecated_string();
+        return data->to_byte_string();
     }
 
     if (role == ModelRole::Sort) {
@@ -156,7 +156,7 @@ Variant JsonArrayModel::data(ModelIndex const& index, ModelRole role) const
     return {};
 }
 
-void JsonArrayModel::set_json_path(DeprecatedString const& json_path)
+void JsonArrayModel::set_json_path(ByteString const& json_path)
 {
     if (m_json_path == json_path)
         return;
diff --git a/Userland/Libraries/LibGUI/JsonArrayModel.h b/Userland/Libraries/LibGUI/JsonArrayModel.h
index 840fd1535b8..91f1980ca71 100644
--- a/Userland/Libraries/LibGUI/JsonArrayModel.h
+++ b/Userland/Libraries/LibGUI/JsonArrayModel.h
@@ -16,7 +16,7 @@ namespace GUI {
 class JsonArrayModel final : public Model {
 public:
     struct FieldSpec {
-        FieldSpec(DeprecatedString const& a_json_field_name, String const& a_column_name, Gfx::TextAlignment a_text_alignment)
+        FieldSpec(ByteString const& a_json_field_name, String const& a_column_name, Gfx::TextAlignment a_text_alignment)
             : json_field_name(a_json_field_name)
             , column_name(a_column_name)
             , text_alignment(a_text_alignment)
@@ -32,7 +32,7 @@ public:
         {
         }
 
-        FieldSpec(DeprecatedString const& a_json_field_name, String const& a_column_name, Gfx::TextAlignment a_text_alignment, Function<Variant(JsonObject const&)>&& a_massage_for_display, Function<Variant(JsonObject const&)>&& a_massage_for_sort = {}, Function<Variant(JsonObject const&)>&& a_massage_for_custom = {})
+        FieldSpec(ByteString const& a_json_field_name, String const& a_column_name, Gfx::TextAlignment a_text_alignment, Function<Variant(JsonObject const&)>&& a_massage_for_display, Function<Variant(JsonObject const&)>&& a_massage_for_sort = {}, Function<Variant(JsonObject const&)>&& a_massage_for_custom = {})
             : json_field_name(a_json_field_name)
             , column_name(a_column_name)
             , text_alignment(a_text_alignment)
@@ -42,7 +42,7 @@ public:
         {
         }
 
-        DeprecatedString json_field_name;
+        ByteString json_field_name;
         String column_name;
         Gfx::TextAlignment text_alignment;
         Function<Variant(JsonObject const&)> massage_for_display;
@@ -50,7 +50,7 @@ public:
         Function<Variant(JsonObject const&)> massage_for_custom;
     };
 
-    static NonnullRefPtr<JsonArrayModel> create(DeprecatedString const& json_path, Vector<FieldSpec>&& fields)
+    static NonnullRefPtr<JsonArrayModel> create(ByteString const& json_path, Vector<FieldSpec>&& fields)
     {
         return adopt_ref(*new JsonArrayModel(json_path, move(fields)));
     }
@@ -64,8 +64,8 @@ public:
     virtual void invalidate() override;
     virtual void update();
 
-    DeprecatedString const& json_path() const { return m_json_path; }
-    void set_json_path(DeprecatedString const& json_path);
+    ByteString const& json_path() const { return m_json_path; }
+    void set_json_path(ByteString const& json_path);
 
     ErrorOr<void> add(Vector<JsonValue> const&& fields);
     ErrorOr<void> set(int row, Vector<JsonValue>&& fields);
@@ -73,13 +73,13 @@ public:
     ErrorOr<void> store();
 
 private:
-    JsonArrayModel(DeprecatedString const& json_path, Vector<FieldSpec>&& fields)
+    JsonArrayModel(ByteString const& json_path, Vector<FieldSpec>&& fields)
         : m_json_path(json_path)
         , m_fields(move(fields))
     {
     }
 
-    DeprecatedString m_json_path;
+    ByteString m_json_path;
     Vector<FieldSpec> m_fields;
     JsonArray m_array;
 };
diff --git a/Userland/Libraries/LibGUI/ListView.cpp b/Userland/Libraries/LibGUI/ListView.cpp
index c584e93b480..9aaa6806977 100644
--- a/Userland/Libraries/LibGUI/ListView.cpp
+++ b/Userland/Libraries/LibGUI/ListView.cpp
@@ -43,7 +43,7 @@ void ListView::update_content_size()
     int content_width = 0;
     for (int row = 0, row_count = model()->row_count(); row < row_count; ++row) {
         auto text = model()->index(row, m_model_column).data();
-        content_width = max(content_width, font().width(text.to_deprecated_string()) + horizontal_padding() * 2);
+        content_width = max(content_width, font().width(text.to_byte_string()) + horizontal_padding() * 2);
     }
     content_width = max(content_width, widget_inner_rect().width());
 
@@ -133,7 +133,7 @@ void ListView::paint_list_item(Painter& painter, int row_index, int painted_item
         text_rect.translate_by(horizontal_padding(), 0);
         text_rect.set_width(text_rect.width() - horizontal_padding() * 2);
         auto text_alignment = index.data(ModelRole::TextAlignment).to_text_alignment(Gfx::TextAlignment::CenterLeft);
-        draw_item_text(painter, index, is_selected_row, text_rect, data.to_deprecated_string(), font, text_alignment, Gfx::TextElision::None);
+        draw_item_text(painter, index, is_selected_row, text_rect, data.to_byte_string(), font, text_alignment, Gfx::TextElision::None);
     }
 }
 
diff --git a/Userland/Libraries/LibGUI/Menu.cpp b/Userland/Libraries/LibGUI/Menu.cpp
index ead7461148f..1e28f626827 100644
--- a/Userland/Libraries/LibGUI/Menu.cpp
+++ b/Userland/Libraries/LibGUI/Menu.cpp
@@ -204,7 +204,7 @@ void Menu::realize_menu_item(MenuItem& item, int item_id)
         break;
     case MenuItem::Type::Action: {
         auto& action = *item.action();
-        auto shortcut_text = action.shortcut().is_valid() ? action.shortcut().to_deprecated_string() : DeprecatedString();
+        auto shortcut_text = action.shortcut().is_valid() ? action.shortcut().to_byte_string() : ByteString();
         bool exclusive = action.group() && action.group()->is_exclusive() && action.is_checkable();
         bool is_default = (m_current_default_action.ptr() == &action);
         auto icon = action.icon() ? action.icon()->to_shareable_bitmap() : Gfx::ShareableBitmap();
@@ -215,7 +215,7 @@ void Menu::realize_menu_item(MenuItem& item, int item_id)
         auto& submenu = *item.submenu();
         submenu.realize_if_needed(m_current_default_action.strong_ref());
         auto icon = submenu.icon() ? submenu.icon()->to_shareable_bitmap() : Gfx::ShareableBitmap();
-        ConnectionToWindowServer::the().async_add_menu_item(m_menu_id, item_id, submenu.menu_id(), submenu.name().to_deprecated_string(), true, true, false, false, false, "", icon, false);
+        ConnectionToWindowServer::the().async_add_menu_item(m_menu_id, item_id, submenu.menu_id(), submenu.name().to_byte_string(), true, true, false, false, false, "", icon, false);
         break;
     }
     case MenuItem::Type::Invalid:
diff --git a/Userland/Libraries/LibGUI/MenuItem.cpp b/Userland/Libraries/LibGUI/MenuItem.cpp
index 0031072da5e..a899f61cecd 100644
--- a/Userland/Libraries/LibGUI/MenuItem.cpp
+++ b/Userland/Libraries/LibGUI/MenuItem.cpp
@@ -83,7 +83,7 @@ void MenuItem::update_window_server()
     switch (m_type) {
     case MenuItem::Type::Action: {
         auto& action = *m_action;
-        auto shortcut_text = action.shortcut().is_valid() ? action.shortcut().to_deprecated_string() : DeprecatedString();
+        auto shortcut_text = action.shortcut().is_valid() ? action.shortcut().to_byte_string() : ByteString();
         auto icon = action.icon() ? action.icon()->to_shareable_bitmap() : Gfx::ShareableBitmap();
         ConnectionToWindowServer::the().async_update_menu_item(m_menu_id, m_identifier, -1, action.text(), action.is_enabled(), action.is_visible(), action.is_checkable(), action.is_checkable() ? action.is_checked() : false, m_default, shortcut_text, icon);
         break;
@@ -91,7 +91,7 @@ void MenuItem::update_window_server()
     case MenuItem::Type::Submenu: {
         auto& submenu = *m_submenu;
         auto icon = submenu.icon() ? submenu.icon()->to_shareable_bitmap() : Gfx::ShareableBitmap();
-        ConnectionToWindowServer::the().async_update_menu_item(m_menu_id, m_identifier, submenu.menu_id(), submenu.name().to_deprecated_string(), m_enabled, m_visible, false, false, m_default, "", icon);
+        ConnectionToWindowServer::the().async_update_menu_item(m_menu_id, m_identifier, submenu.menu_id(), submenu.name().to_byte_string(), m_enabled, m_visible, false, false, m_default, "", icon);
         break;
     }
     default:
diff --git a/Userland/Libraries/LibGUI/MessageBox.cpp b/Userland/Libraries/LibGUI/MessageBox.cpp
index 8b7ef5191e1..0d997e34a3e 100644
--- a/Userland/Libraries/LibGUI/MessageBox.cpp
+++ b/Userland/Libraries/LibGUI/MessageBox.cpp
@@ -20,7 +20,7 @@ ErrorOr<NonnullRefPtr<MessageBox>> MessageBox::create(Window* parent_window, Str
 {
     auto box = TRY(adopt_nonnull_ref_or_enomem(new (nothrow) MessageBox(parent_window, type, input_type)));
     TRY(box->build());
-    box->set_title(TRY(String::from_utf8(title)).to_deprecated_string());
+    box->set_title(TRY(String::from_utf8(title)).to_byte_string());
     box->set_text(TRY(String::from_utf8(text)));
     auto size = box->main_widget()->effective_min_size();
     box->resize(TRY(size.width().shrink_value()), TRY(size.height().shrink_value()));
diff --git a/Userland/Libraries/LibGUI/Model.cpp b/Userland/Libraries/LibGUI/Model.cpp
index f37904c5c16..9db04ac838a 100644
--- a/Userland/Libraries/LibGUI/Model.cpp
+++ b/Userland/Libraries/LibGUI/Model.cpp
@@ -109,12 +109,12 @@ RefPtr<Core::MimeData> Model::mime_data(ModelSelection const& selection) const
         auto text_data = index.data();
         if (!first)
             text_builder.append(", "sv);
-        text_builder.append(text_data.to_deprecated_string());
+        text_builder.append(text_data.to_byte_string());
 
         if (!first)
             data_builder.append('\n');
         auto data = index.data(ModelRole::MimeData);
-        data_builder.append(data.to_deprecated_string());
+        data_builder.append(data.to_byte_string());
 
         first = false;
 
@@ -126,7 +126,7 @@ RefPtr<Core::MimeData> Model::mime_data(ModelSelection const& selection) const
     });
 
     mime_data->set_data(MUST(String::from_utf8(drag_data_type())), data_builder.to_byte_buffer().release_value_but_fixme_should_propagate_errors());
-    mime_data->set_text(text_builder.to_deprecated_string());
+    mime_data->set_text(text_builder.to_byte_string());
     if (bitmap)
         mime_data->set_data("image/x-raw-bitmap"_string, bitmap->serialize_to_byte_buffer().release_value_but_fixme_should_propagate_errors());
 
diff --git a/Userland/Libraries/LibGUI/ModelEditingDelegate.h b/Userland/Libraries/LibGUI/ModelEditingDelegate.h
index dc6e85af234..186d89d6b90 100644
--- a/Userland/Libraries/LibGUI/ModelEditingDelegate.h
+++ b/Userland/Libraries/LibGUI/ModelEditingDelegate.h
@@ -97,7 +97,7 @@ public:
     {
         auto& textbox = static_cast<TextBox&>(*widget());
         if (value.is_valid())
-            textbox.set_text(value.to_deprecated_string());
+            textbox.set_text(value.to_byte_string());
         else
             textbox.clear();
         if (selection_behavior == SelectionBehavior::SelectAll)
diff --git a/Userland/Libraries/LibGUI/Object.cpp b/Userland/Libraries/LibGUI/Object.cpp
index acd51ccc8da..b5b4f2d1da2 100644
--- a/Userland/Libraries/LibGUI/Object.cpp
+++ b/Userland/Libraries/LibGUI/Object.cpp
@@ -15,12 +15,12 @@ Object::Object(Core::EventReceiver* parent)
 
 Object::~Object() = default;
 
-void Object::register_property(DeprecatedString const& name, Function<JsonValue()> getter, Function<bool(JsonValue const&)> setter)
+void Object::register_property(ByteString const& name, Function<JsonValue()> getter, Function<bool(JsonValue const&)> setter)
 {
     m_properties.set(name, make<Property>(name, move(getter), move(setter)));
 }
 
-JsonValue Object::property(DeprecatedString const& name) const
+JsonValue Object::property(ByteString const& name) const
 {
     auto it = m_properties.find(name);
     if (it == m_properties.end())
@@ -28,7 +28,7 @@ JsonValue Object::property(DeprecatedString const& name) const
     return it->value->get();
 }
 
-bool Object::set_property(DeprecatedString const& name, JsonValue const& value)
+bool Object::set_property(ByteString const& name, JsonValue const& value)
 {
     auto it = m_properties.find(name);
     if (it == m_properties.end())
diff --git a/Userland/Libraries/LibGUI/Object.h b/Userland/Libraries/LibGUI/Object.h
index 6bdaff9de5e..9d3dd3b8170 100644
--- a/Userland/Libraries/LibGUI/Object.h
+++ b/Userland/Libraries/LibGUI/Object.h
@@ -50,17 +50,17 @@ class Object : public Core::EventReceiver {
 public:
     virtual ~Object() override;
 
-    bool set_property(DeprecatedString const& name, JsonValue const& value);
-    JsonValue property(DeprecatedString const& name) const;
-    HashMap<DeprecatedString, NonnullOwnPtr<Property>> const& properties() const { return m_properties; }
+    bool set_property(ByteString const& name, JsonValue const& value);
+    JsonValue property(ByteString const& name) const;
+    HashMap<ByteString, NonnullOwnPtr<Property>> const& properties() const { return m_properties; }
 
 protected:
     explicit Object(Core::EventReceiver* parent = nullptr);
 
-    void register_property(DeprecatedString const& name, Function<JsonValue()> getter, Function<bool(JsonValue const&)> setter = nullptr);
+    void register_property(ByteString const& name, Function<JsonValue()> getter, Function<bool(JsonValue const&)> setter = nullptr);
 
 private:
-    HashMap<DeprecatedString, NonnullOwnPtr<Property>> m_properties;
+    HashMap<ByteString, NonnullOwnPtr<Property>> m_properties;
 };
 
 }
@@ -84,13 +84,13 @@ private:
         });
 
 // FIXME: Port JsonValue to the new String class.
-#define REGISTER_STRING_PROPERTY(property_name, getter, setter)                                                                           \
-    register_property(                                                                                                                    \
-        property_name,                                                                                                                    \
-        [this]() { return this->getter().to_deprecated_string(); },                                                                       \
-        [this](auto& value) {                                                                                                             \
-            this->setter(String::from_deprecated_string(value.to_deprecated_string()).release_value_but_fixme_should_propagate_errors()); \
-            return true;                                                                                                                  \
+#define REGISTER_STRING_PROPERTY(property_name, getter, setter)                                                               \
+    register_property(                                                                                                        \
+        property_name,                                                                                                        \
+        [this]() { return this->getter().to_byte_string(); },                                                                 \
+        [this](auto& value) {                                                                                                 \
+            this->setter(String::from_byte_string(value.to_byte_string()).release_value_but_fixme_should_propagate_errors()); \
+            return true;                                                                                                      \
         });
 
 #define REGISTER_DEPRECATED_STRING_PROPERTY(property_name, getter, setter) \
@@ -98,7 +98,7 @@ private:
         property_name,                                                     \
         [this] { return this->getter(); },                                 \
         [this](auto& value) {                                              \
-            this->setter(value.to_deprecated_string());                    \
+            this->setter(value.to_byte_string());                          \
             return true;                                                   \
         });
 
@@ -113,7 +113,7 @@ private:
         property_name,                                             \
         {},                                                        \
         [this](auto& value) {                                      \
-            this->setter(value.to_deprecated_string());            \
+            this->setter(value.to_byte_string());                  \
             return true;                                           \
         });
 
@@ -187,7 +187,7 @@ private:
         [this]() -> JsonValue {                                              \
             struct {                                                         \
                 EnumType enum_value;                                         \
-                DeprecatedString string_value;                               \
+                ByteString string_value;                                     \
             } options[] = { __VA_ARGS__ };                                   \
             auto enum_value = getter();                                      \
             for (size_t i = 0; i < array_size(options); ++i) {               \
@@ -200,7 +200,7 @@ private:
         [this](auto& value) {                                                \
             struct {                                                         \
                 EnumType enum_value;                                         \
-                DeprecatedString string_value;                               \
+                ByteString string_value;                                     \
             } options[] = { __VA_ARGS__ };                                   \
             if (!value.is_string())                                          \
                 return false;                                                \
diff --git a/Userland/Libraries/LibGUI/OpacitySlider.cpp b/Userland/Libraries/LibGUI/OpacitySlider.cpp
index 0fe6c44db1d..b566e6a4ecd 100644
--- a/Userland/Libraries/LibGUI/OpacitySlider.cpp
+++ b/Userland/Libraries/LibGUI/OpacitySlider.cpp
@@ -115,7 +115,7 @@ void OpacitySlider::paint_event(PaintEvent& event)
 
     // Text label
     // FIXME: better support text in vertical orientation, either by having a vertical option for draw_text, or only showing when there is enough space
-    auto percent_text = DeprecatedString::formatted("{}%", (int)((float)value() / (float)max() * 100.0f));
+    auto percent_text = ByteString::formatted("{}%", (int)((float)value() / (float)max() * 100.0f));
     painter.draw_text(inner_rect.translated(1, 1), percent_text, Gfx::TextAlignment::Center, Color::Black);
     painter.draw_text(inner_rect, percent_text, Gfx::TextAlignment::Center, Color::White);
 
diff --git a/Userland/Libraries/LibGUI/PasswordInputDialog.cpp b/Userland/Libraries/LibGUI/PasswordInputDialog.cpp
index 9d8ae8618f3..8800869a13c 100644
--- a/Userland/Libraries/LibGUI/PasswordInputDialog.cpp
+++ b/Userland/Libraries/LibGUI/PasswordInputDialog.cpp
@@ -14,7 +14,7 @@
 
 namespace GUI {
 
-PasswordInputDialog::PasswordInputDialog(Window* parent_window, DeprecatedString title, DeprecatedString server, DeprecatedString username)
+PasswordInputDialog::PasswordInputDialog(Window* parent_window, ByteString title, ByteString server, ByteString username)
     : Dialog(parent_window)
 {
     if (parent_window)
@@ -31,10 +31,10 @@ PasswordInputDialog::PasswordInputDialog(Window* parent_window, DeprecatedString
     key_icon.set_bitmap(Gfx::Bitmap::load_from_file("/res/icons/32x32/key.png"sv).release_value_but_fixme_should_propagate_errors());
 
     auto& server_label = *widget->find_descendant_of_type_named<GUI::Label>("server_label");
-    server_label.set_text(String::from_deprecated_string(server).release_value_but_fixme_should_propagate_errors());
+    server_label.set_text(String::from_byte_string(server).release_value_but_fixme_should_propagate_errors());
 
     auto& username_label = *widget->find_descendant_of_type_named<GUI::Label>("username_label");
-    username_label.set_text(String::from_deprecated_string(username).release_value_but_fixme_should_propagate_errors());
+    username_label.set_text(String::from_byte_string(username).release_value_but_fixme_should_propagate_errors());
 
     auto& password_box = *widget->find_descendant_of_type_named<GUI::PasswordBox>("password_box");
 
@@ -58,7 +58,7 @@ PasswordInputDialog::PasswordInputDialog(Window* parent_window, DeprecatedString
     password_box.set_focus(true);
 }
 
-Dialog::ExecResult PasswordInputDialog::show(Window* parent_window, DeprecatedString& text_value, DeprecatedString title, DeprecatedString server, DeprecatedString username)
+Dialog::ExecResult PasswordInputDialog::show(Window* parent_window, ByteString& text_value, ByteString title, ByteString server, ByteString username)
 {
     auto box = PasswordInputDialog::construct(parent_window, move(title), move(server), move(username));
     auto result = box->exec();
diff --git a/Userland/Libraries/LibGUI/PasswordInputDialog.h b/Userland/Libraries/LibGUI/PasswordInputDialog.h
index 4e7d8f4ef66..474159602aa 100644
--- a/Userland/Libraries/LibGUI/PasswordInputDialog.h
+++ b/Userland/Libraries/LibGUI/PasswordInputDialog.h
@@ -17,12 +17,12 @@ class PasswordInputDialog : public Dialog {
 public:
     virtual ~PasswordInputDialog() override = default;
 
-    static ExecResult show(Window* parent_window, DeprecatedString& text_value, DeprecatedString title, DeprecatedString server, DeprecatedString username);
+    static ExecResult show(Window* parent_window, ByteString& text_value, ByteString title, ByteString server, ByteString username);
 
 private:
-    explicit PasswordInputDialog(Window* parent_window, DeprecatedString title, DeprecatedString server, DeprecatedString username);
+    explicit PasswordInputDialog(Window* parent_window, ByteString title, ByteString server, ByteString username);
 
-    DeprecatedString m_password;
+    ByteString m_password;
 };
 
 }
diff --git a/Userland/Libraries/LibGUI/PathBreadcrumbbar.cpp b/Userland/Libraries/LibGUI/PathBreadcrumbbar.cpp
index 6a82ed983a3..1779f050c3a 100644
--- a/Userland/Libraries/LibGUI/PathBreadcrumbbar.cpp
+++ b/Userland/Libraries/LibGUI/PathBreadcrumbbar.cpp
@@ -87,7 +87,7 @@ PathBreadcrumbbar::PathBreadcrumbbar(NonnullRefPtr<GUI::TextBox> location_text_b
 
 PathBreadcrumbbar::~PathBreadcrumbbar() = default;
 
-void PathBreadcrumbbar::set_current_path(DeprecatedString const& new_path)
+void PathBreadcrumbbar::set_current_path(ByteString const& new_path)
 {
     if (new_path == m_current_path)
         return;
diff --git a/Userland/Libraries/LibGUI/PathBreadcrumbbar.h b/Userland/Libraries/LibGUI/PathBreadcrumbbar.h
index 1aa04f20f51..a819d30839a 100644
--- a/Userland/Libraries/LibGUI/PathBreadcrumbbar.h
+++ b/Userland/Libraries/LibGUI/PathBreadcrumbbar.h
@@ -18,7 +18,7 @@ public:
     static ErrorOr<NonnullRefPtr<PathBreadcrumbbar>> try_create();
     virtual ~PathBreadcrumbbar() override;
 
-    void set_current_path(DeprecatedString const&);
+    void set_current_path(ByteString const&);
 
     void show_location_text_box();
     void hide_location_text_box();
@@ -39,7 +39,7 @@ private:
     NonnullRefPtr<GUI::TextBox> m_location_text_box;
     NonnullRefPtr<GUI::Breadcrumbbar> m_breadcrumbbar;
 
-    DeprecatedString m_current_path;
+    ByteString m_current_path;
 };
 
 }
diff --git a/Userland/Libraries/LibGUI/Process.cpp b/Userland/Libraries/LibGUI/Process.cpp
index 3029fb22512..e62ea5fc02e 100644
--- a/Userland/Libraries/LibGUI/Process.cpp
+++ b/Userland/Libraries/LibGUI/Process.cpp
@@ -13,14 +13,14 @@ void spawn_or_show_error(GUI::Window* parent_window, StringView path, ReadonlySp
 {
     auto spawn_result = Core::Process::spawn(path, arguments, working_directory);
     if (spawn_result.is_error())
-        GUI::MessageBox::show_error(parent_window, DeprecatedString::formatted("Failed to spawn {}: {}", path, spawn_result.error()));
+        GUI::MessageBox::show_error(parent_window, ByteString::formatted("Failed to spawn {}: {}", path, spawn_result.error()));
 }
 
 namespace GUI {
 
-void Process::spawn_or_show_error(Window* parent_window, StringView path, ReadonlySpan<DeprecatedString> arguments, StringView working_directory)
+void Process::spawn_or_show_error(Window* parent_window, StringView path, ReadonlySpan<ByteString> arguments, StringView working_directory)
 {
-    ::spawn_or_show_error<DeprecatedString>(parent_window, path, arguments, working_directory);
+    ::spawn_or_show_error<ByteString>(parent_window, path, arguments, working_directory);
 }
 
 void Process::spawn_or_show_error(Window* parent_window, StringView path, ReadonlySpan<StringView> arguments, StringView working_directory)
diff --git a/Userland/Libraries/LibGUI/Process.h b/Userland/Libraries/LibGUI/Process.h
index 44a5969077d..333abc53285 100644
--- a/Userland/Libraries/LibGUI/Process.h
+++ b/Userland/Libraries/LibGUI/Process.h
@@ -12,7 +12,7 @@
 namespace GUI {
 
 struct Process {
-    static void spawn_or_show_error(Window* parent_window, StringView path, ReadonlySpan<DeprecatedString> arguments, StringView working_directory = {});
+    static void spawn_or_show_error(Window* parent_window, StringView path, ReadonlySpan<ByteString> arguments, StringView working_directory = {});
     static void spawn_or_show_error(Window* parent_window, StringView path, ReadonlySpan<StringView> arguments, StringView working_directory = {});
     static void spawn_or_show_error(Window* parent_window, StringView path, ReadonlySpan<char const*> arguments = {}, StringView working_directory = {});
 };
diff --git a/Userland/Libraries/LibGUI/ProcessChooser.h b/Userland/Libraries/LibGUI/ProcessChooser.h
index cb4d1f6da01..f8a6a7a3eeb 100644
--- a/Userland/Libraries/LibGUI/ProcessChooser.h
+++ b/Userland/Libraries/LibGUI/ProcessChooser.h
@@ -29,7 +29,7 @@ private:
 
     pid_t m_pid { 0 };
 
-    DeprecatedString m_window_title;
+    ByteString m_window_title;
     String m_button_label;
     RefPtr<Gfx::Bitmap const> m_window_icon;
     RefPtr<TableView> m_table_view;
diff --git a/Userland/Libraries/LibGUI/Progressbar.cpp b/Userland/Libraries/LibGUI/Progressbar.cpp
index 4a10ce3ff23..56004cd6e97 100644
--- a/Userland/Libraries/LibGUI/Progressbar.cpp
+++ b/Userland/Libraries/LibGUI/Progressbar.cpp
@@ -56,7 +56,7 @@ void Progressbar::paint_event(PaintEvent& event)
     painter.add_clip_rect(rect);
     painter.add_clip_rect(event.rect());
 
-    DeprecatedString progress_text;
+    ByteString progress_text;
     if (m_format != Format::NoText) {
         // Then we draw the progress text over the gradient.
         // We draw it twice, once offset (1, 1) for a drop shadow look.
@@ -69,7 +69,7 @@ void Progressbar::paint_event(PaintEvent& event)
         } else if (m_format == Format::ValueSlashMax) {
             builder.appendff("{}/{}", m_value, m_max);
         }
-        progress_text = builder.to_deprecated_string();
+        progress_text = builder.to_byte_string();
     }
 
     Gfx::StylePainter::paint_progressbar(painter, rect, palette(), m_min, m_max, m_value, progress_text, m_orientation);
diff --git a/Userland/Libraries/LibGUI/Progressbar.h b/Userland/Libraries/LibGUI/Progressbar.h
index 66fa91be334..cd08650e7ed 100644
--- a/Userland/Libraries/LibGUI/Progressbar.h
+++ b/Userland/Libraries/LibGUI/Progressbar.h
@@ -28,8 +28,8 @@ public:
     void set_orientation(Orientation value);
     Orientation orientation() const { return m_orientation; }
 
-    DeprecatedString text() const { return m_text; }
-    void set_text(DeprecatedString text) { m_text = move(text); }
+    ByteString text() const { return m_text; }
+    void set_text(ByteString text) { m_text = move(text); }
 
     enum Format {
         NoText,
@@ -51,7 +51,7 @@ private:
     int m_min { 0 };
     int m_max { 100 };
     int m_value { 0 };
-    DeprecatedString m_text;
+    ByteString m_text;
     Orientation m_orientation { Orientation::Horizontal };
 };
 
diff --git a/Userland/Libraries/LibGUI/Property.cpp b/Userland/Libraries/LibGUI/Property.cpp
index ea27cf18151..0b930845a9c 100644
--- a/Userland/Libraries/LibGUI/Property.cpp
+++ b/Userland/Libraries/LibGUI/Property.cpp
@@ -9,7 +9,7 @@
 
 namespace GUI {
 
-Property::Property(DeprecatedString name, Function<JsonValue()> getter, Function<bool(JsonValue const&)> setter)
+Property::Property(ByteString name, Function<JsonValue()> getter, Function<bool(JsonValue const&)> setter)
     : m_name(move(name))
     , m_getter(move(getter))
     , m_setter(move(setter))
diff --git a/Userland/Libraries/LibGUI/Property.h b/Userland/Libraries/LibGUI/Property.h
index ed0bc73f2de..4ba9abd5262 100644
--- a/Userland/Libraries/LibGUI/Property.h
+++ b/Userland/Libraries/LibGUI/Property.h
@@ -16,7 +16,7 @@ class Property {
     AK_MAKE_NONCOPYABLE(Property);
 
 public:
-    Property(DeprecatedString name, Function<JsonValue()> getter, Function<bool(JsonValue const&)> setter = nullptr);
+    Property(ByteString name, Function<JsonValue()> getter, Function<bool(JsonValue const&)> setter = nullptr);
     ~Property() = default;
 
     bool set(JsonValue const& value)
@@ -33,11 +33,11 @@ public:
         return m_getter();
     }
 
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
     bool is_readonly() const { return !m_setter; }
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
     Function<JsonValue()> m_getter;
     Function<bool(JsonValue const&)> m_setter;
 };
diff --git a/Userland/Libraries/LibGUI/RangeSlider.cpp b/Userland/Libraries/LibGUI/RangeSlider.cpp
index ac179d06929..e2dba8611e2 100644
--- a/Userland/Libraries/LibGUI/RangeSlider.cpp
+++ b/Userland/Libraries/LibGUI/RangeSlider.cpp
@@ -52,7 +52,7 @@ void RangeSlider::paint_event(PaintEvent& event)
 
     // Text label
     if (m_show_label) {
-        auto range_text = DeprecatedString::formatted("{} to {}", lower_range(), upper_range());
+        auto range_text = ByteString::formatted("{} to {}", lower_range(), upper_range());
         painter.draw_text(inner_rect.translated(1, 1), range_text, Gfx::TextAlignment::Center, Color::Black);
         painter.draw_text(inner_rect, range_text, Gfx::TextAlignment::Center, Color::White);
     }
diff --git a/Userland/Libraries/LibGUI/RunningProcessesModel.h b/Userland/Libraries/LibGUI/RunningProcessesModel.h
index 7a0343c403b..c205110f163 100644
--- a/Userland/Libraries/LibGUI/RunningProcessesModel.h
+++ b/Userland/Libraries/LibGUI/RunningProcessesModel.h
@@ -39,7 +39,7 @@ private:
         pid_t pid;
         uid_t uid;
         RefPtr<Gfx::Bitmap const> icon;
-        DeprecatedString name;
+        ByteString name;
     };
     Vector<Process> m_processes;
 };
diff --git a/Userland/Libraries/LibGUI/SettingsWindow.cpp b/Userland/Libraries/LibGUI/SettingsWindow.cpp
index 6141fa18689..279de98ca94 100644
--- a/Userland/Libraries/LibGUI/SettingsWindow.cpp
+++ b/Userland/Libraries/LibGUI/SettingsWindow.cpp
@@ -23,7 +23,7 @@ void SettingsWindow::set_modified(bool modified)
         m_apply_button->set_enabled(modified);
 }
 
-ErrorOr<NonnullRefPtr<SettingsWindow>> SettingsWindow::create(DeprecatedString title, ShowDefaultsButton show_defaults_button)
+ErrorOr<NonnullRefPtr<SettingsWindow>> SettingsWindow::create(ByteString title, ShowDefaultsButton show_defaults_button)
 {
     auto window = TRY(SettingsWindow::try_create());
 
diff --git a/Userland/Libraries/LibGUI/SettingsWindow.h b/Userland/Libraries/LibGUI/SettingsWindow.h
index 4558f2a8fbb..eadeacc39a6 100644
--- a/Userland/Libraries/LibGUI/SettingsWindow.h
+++ b/Userland/Libraries/LibGUI/SettingsWindow.h
@@ -42,7 +42,7 @@ public:
         No,
     };
 
-    static ErrorOr<NonnullRefPtr<SettingsWindow>> create(DeprecatedString title, ShowDefaultsButton = ShowDefaultsButton::No);
+    static ErrorOr<NonnullRefPtr<SettingsWindow>> create(ByteString title, ShowDefaultsButton = ShowDefaultsButton::No);
 
     virtual ~SettingsWindow() override = default;
 
diff --git a/Userland/Libraries/LibGUI/Shortcut.cpp b/Userland/Libraries/LibGUI/Shortcut.cpp
index 086e7734594..44917109a42 100644
--- a/Userland/Libraries/LibGUI/Shortcut.cpp
+++ b/Userland/Libraries/LibGUI/Shortcut.cpp
@@ -5,16 +5,16 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <AK/Vector.h>
 #include <LibGUI/Shortcut.h>
 
 namespace GUI {
 
-DeprecatedString Shortcut::to_deprecated_string() const
+ByteString Shortcut::to_byte_string() const
 {
-    Vector<DeprecatedString, 8> parts;
+    Vector<ByteString, 8> parts;
 
     if (m_modifiers & Mod_Ctrl)
         parts.append("Ctrl");
@@ -34,14 +34,14 @@ DeprecatedString Shortcut::to_deprecated_string() const
             parts.append("(Invalid)");
     } else {
         if (m_mouse_button != MouseButton::None)
-            parts.append(DeprecatedString::formatted("Mouse {}", mouse_button_to_string(m_mouse_button)));
+            parts.append(ByteString::formatted("Mouse {}", mouse_button_to_string(m_mouse_button)));
         else
             parts.append("(Invalid)");
     }
 
     StringBuilder builder;
     builder.join('+', parts);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/Userland/Libraries/LibGUI/Shortcut.h b/Userland/Libraries/LibGUI/Shortcut.h
index fa8d199dcfd..81884b4c098 100644
--- a/Userland/Libraries/LibGUI/Shortcut.h
+++ b/Userland/Libraries/LibGUI/Shortcut.h
@@ -46,7 +46,7 @@ public:
         Mouse,
     };
 
-    DeprecatedString to_deprecated_string() const;
+    ByteString to_byte_string() const;
     Type type() const { return m_type; }
     bool is_valid() const { return m_type == Type::Keyboard ? (m_keyboard_key != Key_Invalid) : (m_mouse_button != MouseButton::None); }
     u8 modifiers() const { return m_modifiers; }
diff --git a/Userland/Libraries/LibGUI/SpinBox.cpp b/Userland/Libraries/LibGUI/SpinBox.cpp
index 9cf77e14462..97d4f7d0565 100644
--- a/Userland/Libraries/LibGUI/SpinBox.cpp
+++ b/Userland/Libraries/LibGUI/SpinBox.cpp
@@ -63,7 +63,7 @@ SpinBox::SpinBox()
 void SpinBox::set_value(int value, AllowCallback allow_callback)
 {
     value = clamp(value, m_min, m_max);
-    m_editor->set_text(DeprecatedString::number(value));
+    m_editor->set_text(ByteString::number(value));
     if (m_value == value)
         return;
     m_value = value;
@@ -105,7 +105,7 @@ void SpinBox::set_range(int min, int max, AllowCallback allow_callback)
     int old_value = m_value;
     m_value = clamp(m_value, m_min, m_max);
     if (m_value != old_value) {
-        m_editor->set_text(DeprecatedString::number(m_value));
+        m_editor->set_text(ByteString::number(m_value));
         if (on_change && allow_callback == AllowCallback::Yes)
             on_change(m_value);
     }
diff --git a/Userland/Libraries/LibGUI/TabWidget.cpp b/Userland/Libraries/LibGUI/TabWidget.cpp
index cb16676ff3f..7d6d37a5c78 100644
--- a/Userland/Libraries/LibGUI/TabWidget.cpp
+++ b/Userland/Libraries/LibGUI/TabWidget.cpp
@@ -42,7 +42,7 @@ TabWidget::TabWidget()
         "text_alignment",
         [this] { return Gfx::to_string(text_alignment()); },
         [this](auto& value) {
-            auto alignment = Gfx::text_alignment_from_string(value.to_deprecated_string());
+            auto alignment = Gfx::text_alignment_from_string(value.to_byte_string());
             if (alignment.has_value()) {
                 set_text_alignment(alignment.value());
                 return true;
diff --git a/Userland/Libraries/LibGUI/TableView.cpp b/Userland/Libraries/LibGUI/TableView.cpp
index ee8da6c21c6..b37fcc3dc9c 100644
--- a/Userland/Libraries/LibGUI/TableView.cpp
+++ b/Userland/Libraries/LibGUI/TableView.cpp
@@ -131,7 +131,7 @@ void TableView::paint_event(PaintEvent& event)
                     }
 
                     auto text_alignment = cell_index.data(ModelRole::TextAlignment).to_text_alignment(Gfx::TextAlignment::CenterLeft);
-                    draw_item_text(painter, cell_index, is_selected_row, cell_rect, data.to_deprecated_string(), font_for_index(cell_index), text_alignment, Gfx::TextElision::Right);
+                    draw_item_text(painter, cell_index, is_selected_row, cell_rect, data.to_byte_string(), font_for_index(cell_index), text_alignment, Gfx::TextElision::Right);
                 }
             }
 
@@ -208,7 +208,7 @@ void TableView::keydown_event(KeyEvent& event)
                     m_editing_delegate->set_value(GUI::Variant {});
                 }
             } else if (is_backspace) {
-                m_editing_delegate->set_value(DeprecatedString::empty());
+                m_editing_delegate->set_value(ByteString::empty());
             } else {
                 m_editing_delegate->set_value(event.text(), ModelEditingDelegate::SelectionBehavior::DoNotSelect);
             }
diff --git a/Userland/Libraries/LibGUI/TextBox.cpp b/Userland/Libraries/LibGUI/TextBox.cpp
index 4504932fe45..ea256ff8840 100644
--- a/Userland/Libraries/LibGUI/TextBox.cpp
+++ b/Userland/Libraries/LibGUI/TextBox.cpp
@@ -68,7 +68,7 @@ void TextBox::add_current_text_to_history()
     m_saved_input = {};
 }
 
-void TextBox::add_input_to_history(DeprecatedString input)
+void TextBox::add_input_to_history(ByteString input)
 {
     m_history.append(move(input));
     m_history_index++;
diff --git a/Userland/Libraries/LibGUI/TextBox.h b/Userland/Libraries/LibGUI/TextBox.h
index fdc79906d0a..9635cea6a89 100644
--- a/Userland/Libraries/LibGUI/TextBox.h
+++ b/Userland/Libraries/LibGUI/TextBox.h
@@ -32,12 +32,12 @@ private:
     bool has_no_history() const { return !m_history_enabled || m_history.is_empty(); }
     bool can_go_backwards_in_history() const { return m_history_index > 0; }
     bool can_go_forwards_in_history() const { return m_history_index < static_cast<int>(m_history.size()) - 1; }
-    void add_input_to_history(DeprecatedString);
+    void add_input_to_history(ByteString);
 
     bool m_history_enabled { false };
-    Vector<DeprecatedString> m_history;
+    Vector<ByteString> m_history;
     int m_history_index { -1 };
-    DeprecatedString m_saved_input;
+    ByteString m_saved_input;
 };
 
 class PasswordBox : public TextBox {
diff --git a/Userland/Libraries/LibGUI/TextDocument.cpp b/Userland/Libraries/LibGUI/TextDocument.cpp
index 639c2b77721..bf67cc09475 100644
--- a/Userland/Libraries/LibGUI/TextDocument.cpp
+++ b/Userland/Libraries/LibGUI/TextDocument.cpp
@@ -184,7 +184,7 @@ void TextDocument::set_all_cursors(TextPosition const& position)
     }
 }
 
-DeprecatedString TextDocument::text() const
+ByteString TextDocument::text() const
 {
     StringBuilder builder;
     for (size_t i = 0; i < line_count(); ++i) {
@@ -193,14 +193,14 @@ DeprecatedString TextDocument::text() const
         if (i != line_count() - 1)
             builder.append('\n');
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString TextDocument::text_in_range(TextRange const& a_range) const
+ByteString TextDocument::text_in_range(TextRange const& a_range) const
 {
     auto range = a_range.normalized();
     if (is_empty() || line_count() < range.end().line() - range.start().line())
-        return DeprecatedString("");
+        return ByteString("");
 
     StringBuilder builder;
     for (size_t i = range.start().line(); i <= range.end().line(); ++i) {
@@ -219,7 +219,7 @@ DeprecatedString TextDocument::text_in_range(TextRange const& a_range) const
             builder.append('\n');
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // This function will return the position of the previous grapheme cluster
@@ -301,7 +301,7 @@ void TextDocument::update_regex_matches(StringView needle)
         }
         re.search(views, m_regex_result);
         m_regex_needs_update = false;
-        m_regex_needle = DeprecatedString { needle };
+        m_regex_needle = ByteString { needle };
         m_regex_result_match_index = -1;
         m_regex_result_match_capture_group_index = -1;
     }
@@ -694,14 +694,14 @@ TextDocumentUndoCommand::TextDocumentUndoCommand(TextDocument& document)
 {
 }
 
-InsertTextCommand::InsertTextCommand(TextDocument& document, DeprecatedString const& text, TextPosition const& position)
+InsertTextCommand::InsertTextCommand(TextDocument& document, ByteString const& text, TextPosition const& position)
     : TextDocumentUndoCommand(document)
     , m_text(text)
     , m_range({ position, position })
 {
 }
 
-DeprecatedString InsertTextCommand::action_text() const
+ByteString InsertTextCommand::action_text() const
 {
     return "Insert Text";
 }
@@ -723,7 +723,7 @@ bool InsertTextCommand::merge_with(GUI::Command const& other)
     StringBuilder builder(m_text.length() + typed_other.m_text.length());
     builder.append(m_text);
     builder.append(typed_other.m_text);
-    m_text = builder.to_deprecated_string();
+    m_text = builder.to_byte_string();
     m_range.set_end(typed_other.m_range.end());
 
     m_timestamp = MonotonicTime::now();
@@ -777,7 +777,7 @@ void InsertTextCommand::perform_formatting(TextDocument::Client const& client)
             ++column;
         }
     }
-    m_text = builder.to_deprecated_string();
+    m_text = builder.to_byte_string();
 }
 
 void InsertTextCommand::redo()
@@ -795,7 +795,7 @@ void InsertTextCommand::undo()
     m_document.set_all_cursors(m_range.start());
 }
 
-RemoveTextCommand::RemoveTextCommand(TextDocument& document, DeprecatedString const& text, TextRange const& range, TextPosition const& original_cursor_position)
+RemoveTextCommand::RemoveTextCommand(TextDocument& document, ByteString const& text, TextRange const& range, TextPosition const& original_cursor_position)
     : TextDocumentUndoCommand(document)
     , m_text(text)
     , m_range(range)
@@ -803,7 +803,7 @@ RemoveTextCommand::RemoveTextCommand(TextDocument& document, DeprecatedString co
 {
 }
 
-DeprecatedString RemoveTextCommand::action_text() const
+ByteString RemoveTextCommand::action_text() const
 {
     return "Remove Text";
 }
@@ -824,7 +824,7 @@ bool RemoveTextCommand::merge_with(GUI::Command const& other)
     StringBuilder builder(m_text.length() + typed_other.m_text.length());
     builder.append(typed_other.m_text);
     builder.append(m_text);
-    m_text = builder.to_deprecated_string();
+    m_text = builder.to_byte_string();
     m_range.set_start(typed_other.m_range.start());
 
     m_timestamp = MonotonicTime::now();
@@ -843,7 +843,7 @@ void RemoveTextCommand::undo()
     m_document.set_all_cursors(m_original_cursor_position);
 }
 
-InsertLineCommand::InsertLineCommand(TextDocument& document, TextPosition cursor, DeprecatedString&& text, InsertPosition pos)
+InsertLineCommand::InsertLineCommand(TextDocument& document, TextPosition cursor, ByteString&& text, InsertPosition pos)
     : TextDocumentUndoCommand(document)
     , m_cursor(cursor)
     , m_text(move(text))
@@ -876,7 +876,7 @@ size_t InsertLineCommand::compute_line_number() const
     VERIFY_NOT_REACHED();
 }
 
-DeprecatedString InsertLineCommand::action_text() const
+ByteString InsertLineCommand::action_text() const
 {
     StringBuilder action_text_builder;
     action_text_builder.append("Insert Line"sv);
@@ -889,10 +889,10 @@ DeprecatedString InsertLineCommand::action_text() const
         VERIFY_NOT_REACHED();
     }
 
-    return action_text_builder.to_deprecated_string();
+    return action_text_builder.to_byte_string();
 }
 
-ReplaceAllTextCommand::ReplaceAllTextCommand(GUI::TextDocument& document, DeprecatedString const& text, DeprecatedString const& action_text)
+ReplaceAllTextCommand::ReplaceAllTextCommand(GUI::TextDocument& document, ByteString const& text, ByteString const& action_text)
     : TextDocumentUndoCommand(document)
     , m_original_text(document.text())
     , m_new_text(text)
@@ -917,7 +917,7 @@ bool ReplaceAllTextCommand::merge_with(GUI::Command const&)
     return false;
 }
 
-DeprecatedString ReplaceAllTextCommand::action_text() const
+ByteString ReplaceAllTextCommand::action_text() const
 {
     return m_action_text;
 }
@@ -931,7 +931,7 @@ IndentSelection::IndentSelection(TextDocument& document, size_t tab_width, TextR
 
 void IndentSelection::redo()
 {
-    auto const tab = DeprecatedString::repeated(' ', m_tab_width);
+    auto const tab = ByteString::repeated(' ', m_tab_width);
 
     for (size_t i = m_range.start().line(); i <= m_range.end().line(); i++) {
         m_document.insert_at({ i, 0 }, tab, m_client);
@@ -970,7 +970,7 @@ void UnindentSelection::redo()
 
 void UnindentSelection::undo()
 {
-    auto const tab = DeprecatedString::repeated(' ', m_tab_width);
+    auto const tab = ByteString::repeated(' ', m_tab_width);
 
     for (size_t i = m_range.start().line(); i <= m_range.end().line(); i++)
         m_document.insert_at({ i, 0 }, tab, m_client);
diff --git a/Userland/Libraries/LibGUI/TextDocument.h b/Userland/Libraries/LibGUI/TextDocument.h
index 1ea3be44178..4dd0dc62779 100644
--- a/Userland/Libraries/LibGUI/TextDocument.h
+++ b/Userland/Libraries/LibGUI/TextDocument.h
@@ -84,8 +84,8 @@ public:
 
     virtual void update_views(Badge<TextDocumentLine>) override;
 
-    DeprecatedString text() const;
-    DeprecatedString text_in_range(TextRange const&) const;
+    ByteString text() const;
+    ByteString text_in_range(TextRange const&) const;
 
     Vector<TextRange> find_all(StringView needle, bool regmatch = false, bool match_case = true);
 
@@ -147,7 +147,7 @@ private:
     size_t m_regex_result_match_capture_group_index { 0 };
 
     bool m_regex_needs_update { true };
-    DeprecatedString m_regex_needle;
+    ByteString m_regex_needle;
 };
 
 class TextDocumentUndoCommand : public Command {
@@ -173,33 +173,33 @@ protected:
 
 class InsertTextCommand : public TextDocumentUndoCommand {
 public:
-    InsertTextCommand(TextDocument&, DeprecatedString const&, TextPosition const&);
+    InsertTextCommand(TextDocument&, ByteString const&, TextPosition const&);
     virtual ~InsertTextCommand() = default;
     virtual void perform_formatting(TextDocument::Client const&) override;
     virtual void undo() override;
     virtual void redo() override;
     virtual bool merge_with(GUI::Command const&) override;
-    virtual DeprecatedString action_text() const override;
-    DeprecatedString const& text() const { return m_text; }
+    virtual ByteString action_text() const override;
+    ByteString const& text() const { return m_text; }
     TextRange const& range() const { return m_range; }
 
 private:
-    DeprecatedString m_text;
+    ByteString m_text;
     TextRange m_range;
 };
 
 class RemoveTextCommand : public TextDocumentUndoCommand {
 public:
-    RemoveTextCommand(TextDocument&, DeprecatedString const&, TextRange const&, TextPosition const&);
+    RemoveTextCommand(TextDocument&, ByteString const&, TextRange const&, TextPosition const&);
     virtual ~RemoveTextCommand() = default;
     virtual void undo() override;
     virtual void redo() override;
     TextRange const& range() const { return m_range; }
     virtual bool merge_with(GUI::Command const&) override;
-    virtual DeprecatedString action_text() const override;
+    virtual ByteString action_text() const override;
 
 private:
-    DeprecatedString m_text;
+    ByteString m_text;
     TextRange m_range;
     TextPosition m_original_cursor_position;
 };
@@ -211,35 +211,35 @@ public:
         Below,
     };
 
-    InsertLineCommand(TextDocument&, TextPosition, DeprecatedString&&, InsertPosition);
+    InsertLineCommand(TextDocument&, TextPosition, ByteString&&, InsertPosition);
     virtual ~InsertLineCommand() = default;
     virtual void undo() override;
     virtual void redo() override;
-    virtual DeprecatedString action_text() const override;
+    virtual ByteString action_text() const override;
 
 private:
     size_t compute_line_number() const;
 
     TextPosition m_cursor;
-    DeprecatedString m_text;
+    ByteString m_text;
     InsertPosition m_pos;
 };
 
 class ReplaceAllTextCommand final : public GUI::TextDocumentUndoCommand {
 
 public:
-    ReplaceAllTextCommand(GUI::TextDocument& document, DeprecatedString const& new_text, DeprecatedString const& action_text);
+    ReplaceAllTextCommand(GUI::TextDocument& document, ByteString const& new_text, ByteString const& action_text);
     virtual ~ReplaceAllTextCommand() = default;
     void redo() override;
     void undo() override;
     bool merge_with(GUI::Command const&) override;
-    DeprecatedString action_text() const override;
-    DeprecatedString const& text() const { return m_new_text; }
+    ByteString action_text() const override;
+    ByteString const& text() const { return m_new_text; }
 
 private:
-    DeprecatedString m_original_text;
-    DeprecatedString m_new_text;
-    DeprecatedString m_action_text;
+    ByteString m_original_text;
+    ByteString m_new_text;
+    ByteString m_action_text;
 };
 
 class IndentSelection : public TextDocumentUndoCommand {
diff --git a/Userland/Libraries/LibGUI/TextEditor.cpp b/Userland/Libraries/LibGUI/TextEditor.cpp
index 4d8099a4d8e..beac385f592 100644
--- a/Userland/Libraries/LibGUI/TextEditor.cpp
+++ b/Userland/Libraries/LibGUI/TextEditor.cpp
@@ -248,7 +248,7 @@ TextPosition TextEditor::text_position_at(Gfx::IntPoint widget_position) const
     return text_position_at_content_position(content_position);
 }
 
-void TextEditor::highlight_all_occurances_of(DeprecatedString const selected_text)
+void TextEditor::highlight_all_occurances_of(ByteString const selected_text)
 {
     auto search_result = document().find_all(selected_text, false, true);
     if (search_result.size() > 1) {
@@ -677,7 +677,7 @@ void TextEditor::paint_event(PaintEvent& event)
             size_t const line_number = is_relative_line_number() && !is_current_line ? max(i, m_cursor.line()) - min(i, m_cursor.line()) : i + 1;
             painter.draw_text(
                 ruler_line_rect.shrunken(2, 0),
-                DeprecatedString::number(line_number),
+                ByteString::number(line_number),
                 is_current_line ? font().bold_variant() : font(),
                 Gfx::TextAlignment::CenterRight,
                 is_current_line ? palette().ruler_active_text() : palette().ruler_inactive_text());
@@ -1081,7 +1081,7 @@ void TextEditor::keydown_event(KeyEvent& event)
             return;
 
         size_t indent_length = current_line().leading_spaces();
-        DeprecatedString indent = current_line().to_utf8().substring(0, indent_length);
+        ByteString indent = current_line().to_utf8().substring(0, indent_length);
         auto insert_pos = event.shift() ? InsertLineCommand::InsertPosition::Above : InsertLineCommand::InsertPosition::Below;
         execute<InsertLineCommand>(m_cursor, move(indent), insert_pos);
         return;
@@ -1394,7 +1394,7 @@ void TextEditor::add_code_point(u32 code_point)
         else
             m_autocomplete_timer->start();
     }
-    insert_at_cursor_or_replace_selection(sb.to_deprecated_string());
+    insert_at_cursor_or_replace_selection(sb.to_byte_string());
 }
 
 void TextEditor::reset_cursor_blink()
@@ -1712,7 +1712,7 @@ ErrorOr<void> TextEditor::write_to_file(Core::File& file)
     return {};
 }
 
-DeprecatedString TextEditor::text() const
+ByteString TextEditor::text() const
 {
     return document().text();
 }
@@ -1727,7 +1727,7 @@ void TextEditor::clear()
     update();
 }
 
-DeprecatedString TextEditor::selected_text() const
+ByteString TextEditor::selected_text() const
 {
     if (!has_selection())
         return {};
@@ -1863,7 +1863,7 @@ void TextEditor::paste()
     if (data.is_empty())
         return;
 
-    dbgln_if(TEXTEDITOR_DEBUG, "Paste: \"{}\"", DeprecatedString::copy(data));
+    dbgln_if(TEXTEDITOR_DEBUG, "Paste: \"{}\"", ByteString::copy(data));
 
     TemporaryChange change(m_automatic_indentation_enabled, false);
     insert_at_cursor_or_replace_selection(data);
@@ -2292,7 +2292,7 @@ void TextEditor::document_did_update_undo_stack()
             builder.append(' ');
             builder.append(suffix.value());
         }
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
 
     m_undo_action->set_enabled(can_undo() && !text_is_secret());
@@ -2333,7 +2333,7 @@ void TextEditor::cursor_did_change()
     hide_autocomplete_if_needed();
 }
 
-void TextEditor::clipboard_content_did_change(DeprecatedString const& mime_type)
+void TextEditor::clipboard_content_did_change(ByteString const& mime_type)
 {
     m_paste_action->set_enabled(is_editable() && mime_type.starts_with("text/"sv));
 }
diff --git a/Userland/Libraries/LibGUI/TextEditor.h b/Userland/Libraries/LibGUI/TextEditor.h
index 789d7a54b22..791db0673a7 100644
--- a/Userland/Libraries/LibGUI/TextEditor.h
+++ b/Userland/Libraries/LibGUI/TextEditor.h
@@ -57,7 +57,7 @@ public:
 
     virtual void set_document(TextDocument&);
 
-    DeprecatedString const& placeholder() const { return m_placeholder; }
+    ByteString const& placeholder() const { return m_placeholder; }
     void set_placeholder(StringView placeholder) { m_placeholder = placeholder; }
 
     TextDocumentLine& current_line() { return line(m_cursor.line()); }
@@ -142,7 +142,7 @@ public:
     ErrorOr<void> write_to_file(StringView path);
     ErrorOr<void> write_to_file(Core::File&);
     bool has_selection() const { return m_selection.is_valid(); }
-    DeprecatedString selected_text() const;
+    ByteString selected_text() const;
     size_t number_of_words() const;
     size_t number_of_selected_words() const;
     void set_selection(TextRange const&);
@@ -150,7 +150,7 @@ public:
     bool can_undo() const { return document().can_undo(); }
     bool can_redo() const { return document().can_redo(); }
 
-    DeprecatedString text() const;
+    ByteString text() const;
 
     void clear();
 
@@ -245,7 +245,7 @@ public:
         Backward,
     };
     TextRange find_text(StringView needle, SearchDirection, GUI::TextDocument::SearchShouldWrap, bool use_regex, bool match_case);
-    void highlight_all_occurances_of(DeprecatedString const selected_text);
+    void highlight_all_occurances_of(ByteString const selected_text);
     void reset_search_results();
     Optional<size_t> search_result_index() const { return m_search_result_index; }
     Vector<TextRange> const& search_results() const { return m_search_results; }
@@ -312,12 +312,12 @@ private:
     virtual Vector<GUI::TextDocumentFoldingRegion>& folding_regions() final { return document().folding_regions(); }
     virtual Vector<GUI::TextDocumentFoldingRegion> const& folding_regions() const final { return document().folding_regions(); }
     virtual void highlighter_did_request_update() final { update(); }
-    virtual DeprecatedString highlighter_did_request_text() const final { return text(); }
+    virtual ByteString highlighter_did_request_text() const final { return text(); }
     virtual GUI::TextDocument& highlighter_did_request_document() final { return document(); }
     virtual GUI::TextPosition highlighter_did_request_cursor() const final { return m_cursor; }
 
     // ^Clipboard::ClipboardClient
-    virtual void clipboard_content_did_change(DeprecatedString const& mime_type) override;
+    virtual void clipboard_content_did_change(ByteString const& mime_type) override;
 
     // ^GUI::AbstractScrollableWidget
     virtual void automatic_scrolling_timer_did_fire() override;
@@ -441,7 +441,7 @@ private:
 
     RefPtr<TextDocument> m_document;
 
-    DeprecatedString m_placeholder { "" };
+    ByteString m_placeholder { "" };
 
     template<typename Callback>
     void for_each_visual_line(size_t line_index, Callback) const;
diff --git a/Userland/Libraries/LibGUI/Toolbar.cpp b/Userland/Libraries/LibGUI/Toolbar.cpp
index e33a89ba527..9d28b8f1474 100644
--- a/Userland/Libraries/LibGUI/Toolbar.cpp
+++ b/Userland/Libraries/LibGUI/Toolbar.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/EventLoop.h>
 #include <LibGUI/Action.h>
@@ -54,7 +54,7 @@ private:
         if (action.icon())
             set_icon(action.icon());
         else
-            set_text(String::from_deprecated_string(action.text()).release_value_but_fixme_should_propagate_errors());
+            set_text(String::from_byte_string(action.text()).release_value_but_fixme_should_propagate_errors());
         set_button_style(Gfx::ButtonStyle::Coolbar);
     }
 
@@ -74,7 +74,7 @@ private:
         builder.append(action.tooltip());
         if (action.shortcut().is_valid()) {
             builder.append(" ("sv);
-            builder.append(action.shortcut().to_deprecated_string());
+            builder.append(action.shortcut().to_byte_string());
             builder.append(')');
         }
         return MUST(builder.to_string());
diff --git a/Userland/Libraries/LibGUI/Tray.cpp b/Userland/Libraries/LibGUI/Tray.cpp
index 0bd74aa637d..5ac0599ece7 100644
--- a/Userland/Libraries/LibGUI/Tray.cpp
+++ b/Userland/Libraries/LibGUI/Tray.cpp
@@ -33,7 +33,7 @@ Gfx::IntRect Tray::Item::rect(Tray const& tray) const
     };
 }
 
-size_t Tray::add_item(DeprecatedString text, RefPtr<Gfx::Bitmap const> bitmap, DeprecatedString custom_data)
+size_t Tray::add_item(ByteString text, RefPtr<Gfx::Bitmap const> bitmap, ByteString custom_data)
 {
     auto new_index = m_items.size();
 
diff --git a/Userland/Libraries/LibGUI/Tray.h b/Userland/Libraries/LibGUI/Tray.h
index ef0e2eba408..04b1bbe9259 100644
--- a/Userland/Libraries/LibGUI/Tray.h
+++ b/Userland/Libraries/LibGUI/Tray.h
@@ -18,11 +18,11 @@ class Tray : public GUI::Frame {
 public:
     virtual ~Tray() override = default;
 
-    size_t add_item(DeprecatedString text, RefPtr<Gfx::Bitmap const>, DeprecatedString custom_data);
+    size_t add_item(ByteString text, RefPtr<Gfx::Bitmap const>, ByteString custom_data);
 
     void set_item_checked(size_t index, bool);
 
-    Function<void(DeprecatedString const&)> on_item_activation;
+    Function<void(ByteString const&)> on_item_activation;
 
 protected:
     virtual void paint_event(GUI::PaintEvent&) override;
@@ -38,9 +38,9 @@ private:
     Tray();
 
     struct Item {
-        DeprecatedString text;
+        ByteString text;
         RefPtr<Gfx::Bitmap const> bitmap;
-        DeprecatedString custom_data;
+        ByteString custom_data;
         size_t index { 0 };
         Gfx::IntRect rect(Tray const&) const;
     };
diff --git a/Userland/Libraries/LibGUI/TreeView.cpp b/Userland/Libraries/LibGUI/TreeView.cpp
index b9898f5c596..3fa73039591 100644
--- a/Userland/Libraries/LibGUI/TreeView.cpp
+++ b/Userland/Libraries/LibGUI/TreeView.cpp
@@ -185,7 +185,7 @@ void TreeView::traverse_in_paint_order(Callback callback) const
         if (index.is_valid()) {
             auto& metadata = ensure_metadata_for_index(index);
             int x_offset = tree_column_x_offset + horizontal_padding() + indent_level * indent_width_in_pixels();
-            auto node_text = index.data().to_deprecated_string();
+            auto node_text = index.data().to_byte_string();
             Gfx::IntRect rect = {
                 x_offset, y_offset,
                 static_cast<int>(ceilf(icon_size() + icon_spacing() + text_padding() + font_for_index(index)->width(node_text) + text_padding())), row_height()
@@ -317,7 +317,7 @@ void TreeView::paint_event(PaintEvent& event)
                         }
                     } else {
                         auto text_alignment = cell_index.data(ModelRole::TextAlignment).to_text_alignment(Gfx::TextAlignment::CenterLeft);
-                        draw_item_text(painter, cell_index, is_selected_row, cell_rect, data.to_deprecated_string(), font_for_index(cell_index), text_alignment, Gfx::TextElision::Right);
+                        draw_item_text(painter, cell_index, is_selected_row, cell_rect, data.to_byte_string(), font_for_index(cell_index), text_alignment, Gfx::TextElision::Right);
                     }
                 }
             } else {
@@ -347,7 +347,7 @@ void TreeView::paint_event(PaintEvent& event)
                 }
                 auto display_data = index.data();
                 if (display_data.is_string() || display_data.is_u32() || display_data.is_i32() || display_data.is_u64() || display_data.is_i64() || display_data.is_bool() || display_data.is_float())
-                    draw_item_text(painter, index, is_selected_row, text_rect, display_data.to_deprecated_string(), font_for_index(index), Gfx::TextAlignment::CenterLeft, Gfx::TextElision::Right);
+                    draw_item_text(painter, index, is_selected_row, text_rect, display_data.to_byte_string(), font_for_index(index), Gfx::TextAlignment::CenterLeft, Gfx::TextElision::Right);
 
                 if (selection_behavior() == SelectionBehavior::SelectItems && is_focused() && index == cursor_index()) {
                     painter.draw_rect(background_rect, palette().color(background_role()));
@@ -687,7 +687,7 @@ void TreeView::auto_resize_column(int column)
         } else if (cell_data.is_bitmap()) {
             cell_width = cell_data.as_bitmap().width();
         } else if (cell_data.is_valid()) {
-            cell_width = font().width(cell_data.to_deprecated_string());
+            cell_width = font().width(cell_data.to_byte_string());
         }
         if (is_empty && cell_width > 0)
             is_empty = false;
@@ -730,7 +730,7 @@ void TreeView::update_column_sizes()
             } else if (cell_data.is_bitmap()) {
                 cell_width = cell_data.as_bitmap().width();
             } else if (cell_data.is_valid()) {
-                cell_width = font().width(cell_data.to_deprecated_string());
+                cell_width = font().width(cell_data.to_byte_string());
             }
             column_width = max(column_width, cell_width);
             return IterationDecision::Continue;
@@ -747,7 +747,7 @@ void TreeView::update_column_sizes()
         auto cell_data = model.index(index.row(), tree_column, index.parent()).data();
         int cell_width = 0;
         if (cell_data.is_valid()) {
-            cell_width = font().width(cell_data.to_deprecated_string());
+            cell_width = font().width(cell_data.to_byte_string());
             cell_width += horizontal_padding() * 2 + indent_level * indent_width_in_pixels() + icon_size() / 2 + text_padding() * 2;
         }
         tree_column_width = max(tree_column_width, cell_width);
diff --git a/Userland/Libraries/LibGUI/TreeViewModel.h b/Userland/Libraries/LibGUI/TreeViewModel.h
index b063e939a18..14938c2b720 100644
--- a/Userland/Libraries/LibGUI/TreeViewModel.h
+++ b/Userland/Libraries/LibGUI/TreeViewModel.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/Optional.h>
 #include <AK/RefPtr.h>
@@ -35,7 +35,7 @@ public:
         : public RefCounted<Node>
         , public Weakable<Node> {
     public:
-        Node(DeprecatedString text, Optional<Icon> icon, Node* parent_node = nullptr)
+        Node(ByteString text, Optional<Icon> icon, Node* parent_node = nullptr)
             : m_text(move(text))
             , m_icon(move(icon))
             , m_parent_node(parent_node)
@@ -45,7 +45,7 @@ public:
         virtual ~Node() = default;
 
         template<typename NodeType = Node, typename... Args>
-        NonnullRefPtr<NodeType> add_node(DeprecatedString text, Optional<Icon> icon, Args&&... args)
+        NonnullRefPtr<NodeType> add_node(ByteString text, Optional<Icon> icon, Args&&... args)
         requires(IsBaseOf<Node, NodeType>)
         {
             auto node = adopt_ref(*new NodeType(move(text), move(icon), this, forward<Args>(args)...));
@@ -53,7 +53,7 @@ public:
             return node;
         }
 
-        DeprecatedString const& text() const { return m_text; }
+        ByteString const& text() const { return m_text; }
         Optional<Icon> const& icon() const { return m_icon; }
 
         Node const* parent_node() const { return m_parent_node; }
@@ -63,7 +63,7 @@ public:
         Vector<NonnullRefPtr<Node>>& child_nodes() { return m_child_nodes; }
 
     private:
-        DeprecatedString m_text;
+        ByteString m_text;
         Optional<Icon> m_icon;
         WeakPtr<Node> m_parent_node;
         Vector<NonnullRefPtr<Node>> m_child_nodes;
@@ -73,7 +73,7 @@ public:
     Vector<NonnullRefPtr<Node>>& nodes() { return m_nodes; }
 
     template<typename NodeType = Node, typename... Args>
-    NonnullRefPtr<NodeType> add_node(DeprecatedString text, Optional<Icon> icon, Args&&... args)
+    NonnullRefPtr<NodeType> add_node(ByteString text, Optional<Icon> icon, Args&&... args)
     requires(IsBaseOf<Node, NodeType>)
     {
         auto node = adopt_ref(*new NodeType(move(text), move(icon), nullptr, forward<Args>(args)...));
diff --git a/Userland/Libraries/LibGUI/UIDimensions.h b/Userland/Libraries/LibGUI/UIDimensions.h
index 8ccf0cd40ea..9a9d6fce427 100644
--- a/Userland/Libraries/LibGUI/UIDimensions.h
+++ b/Userland/Libraries/LibGUI/UIDimensions.h
@@ -169,7 +169,7 @@ public:
     [[nodiscard]] static Optional<UIDimension> construct_from_json_value(AK::JsonValue const value)
     {
         if (value.is_string()) {
-            DeprecatedString value_literal = value.as_string();
+            ByteString value_literal = value.as_string();
             if (value_literal == "shrink")
                 return UIDimension { SpecialDimension::Shrink };
             else if (value_literal == "grow")
diff --git a/Userland/Libraries/LibGUI/UndoStack.cpp b/Userland/Libraries/LibGUI/UndoStack.cpp
index c607a94d8d5..73c8983bd36 100644
--- a/Userland/Libraries/LibGUI/UndoStack.cpp
+++ b/Userland/Libraries/LibGUI/UndoStack.cpp
@@ -111,14 +111,14 @@ void UndoStack::clear()
         on_state_change();
 }
 
-Optional<DeprecatedString> UndoStack::undo_action_text() const
+Optional<ByteString> UndoStack::undo_action_text() const
 {
     if (!can_undo())
         return {};
     return m_stack[m_stack_index - 1]->action_text();
 }
 
-Optional<DeprecatedString> UndoStack::redo_action_text() const
+Optional<ByteString> UndoStack::redo_action_text() const
 {
     if (!can_redo())
         return {};
diff --git a/Userland/Libraries/LibGUI/UndoStack.h b/Userland/Libraries/LibGUI/UndoStack.h
index 81a11df83d0..9dcb2413588 100644
--- a/Userland/Libraries/LibGUI/UndoStack.h
+++ b/Userland/Libraries/LibGUI/UndoStack.h
@@ -35,8 +35,8 @@ public:
 
     void clear();
 
-    Optional<DeprecatedString> undo_action_text() const;
-    Optional<DeprecatedString> redo_action_text() const;
+    Optional<ByteString> undo_action_text() const;
+    Optional<ByteString> redo_action_text() const;
 
     Function<void()> on_state_change;
 
diff --git a/Userland/Libraries/LibGUI/ValueSlider.cpp b/Userland/Libraries/LibGUI/ValueSlider.cpp
index 60bb95a39eb..34704a8c031 100644
--- a/Userland/Libraries/LibGUI/ValueSlider.cpp
+++ b/Userland/Libraries/LibGUI/ValueSlider.cpp
@@ -32,7 +32,7 @@ ValueSlider::ValueSlider(Gfx::Orientation orientation, String suffix)
     m_textbox->set_font_size(8);
 
     m_textbox->on_change = [&]() {
-        DeprecatedString value = m_textbox->text();
+        ByteString value = m_textbox->text();
         if (value.ends_with(m_suffix, AK::CaseSensitivity::CaseInsensitive))
             value = value.substring_view(0, value.length() - m_suffix.bytes_as_string_view().length());
         auto integer_value = value.to_int();
@@ -68,9 +68,9 @@ ValueSlider::ValueSlider(Gfx::Orientation orientation, String suffix)
     };
 }
 
-DeprecatedString ValueSlider::formatted_value() const
+ByteString ValueSlider::formatted_value() const
 {
-    return DeprecatedString::formatted("{:2}{}", value(), m_suffix);
+    return ByteString::formatted("{:2}{}", value(), m_suffix);
 }
 
 void ValueSlider::paint_event(PaintEvent& event)
diff --git a/Userland/Libraries/LibGUI/ValueSlider.h b/Userland/Libraries/LibGUI/ValueSlider.h
index 96db34c3744..5deb5c8ae50 100644
--- a/Userland/Libraries/LibGUI/ValueSlider.h
+++ b/Userland/Libraries/LibGUI/ValueSlider.h
@@ -39,7 +39,7 @@ protected:
 private:
     explicit ValueSlider(Gfx::Orientation = Gfx::Orientation::Horizontal, String suffix = {});
 
-    DeprecatedString formatted_value() const;
+    ByteString formatted_value() const;
     int value_at(Gfx::IntPoint position) const;
     Gfx::IntRect bar_rect() const;
     Gfx::IntRect knob_rect() const;
diff --git a/Userland/Libraries/LibGUI/Variant.cpp b/Userland/Libraries/LibGUI/Variant.cpp
index 6646e2cad8f..516df7312a7 100644
--- a/Userland/Libraries/LibGUI/Variant.cpp
+++ b/Userland/Libraries/LibGUI/Variant.cpp
@@ -72,11 +72,11 @@ bool Variant::operator==(Variant const& other) const
                     return &own_value.impl() == &other_value.impl();
                 // FIXME: Figure out if this silly behavior is actually used anywhere, then get rid of it.
                 else
-                    return to_deprecated_string() == other.to_deprecated_string();
+                    return to_byte_string() == other.to_byte_string();
             },
             [&](auto const&) {
                 // FIXME: Figure out if this silly behavior is actually used anywhere, then get rid of it.
-                return to_deprecated_string() == other.to_deprecated_string();
+                return to_byte_string() == other.to_byte_string();
             });
     });
 }
@@ -98,10 +98,10 @@ bool Variant::operator<(Variant const& other) const
                     return own_value < other_value;
                 // FIXME: Figure out if this silly behavior is actually used anywhere, then get rid of it.
                 else
-                    return to_deprecated_string() < other.to_deprecated_string();
+                    return to_byte_string() < other.to_byte_string();
             },
             [&](auto const&) -> bool {
-                return to_deprecated_string() < other.to_deprecated_string(); // FIXME: Figure out if this silly behavior is actually used anywhere, then get rid of it.
+                return to_byte_string() < other.to_byte_string(); // FIXME: Figure out if this silly behavior is actually used anywhere, then get rid of it.
             });
     });
 }
diff --git a/Userland/Libraries/LibGUI/Variant.h b/Userland/Libraries/LibGUI/Variant.h
index eb6b7f74043..c48a71895f8 100644
--- a/Userland/Libraries/LibGUI/Variant.h
+++ b/Userland/Libraries/LibGUI/Variant.h
@@ -8,8 +8,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/Concepts.h>
-#include <AK/DeprecatedString.h>
 #include <LibGUI/Icon.h>
 #include <LibGfx/Bitmap.h>
 #include <LibGfx/Font/Font.h>
@@ -21,7 +21,7 @@ namespace Detail {
 struct Boolean {
     bool value;
 };
-using VariantUnderlyingType = AK::Variant<Empty, Boolean, float, double, i32, i64, u32, u64, DeprecatedString, Color, Gfx::IntPoint, Gfx::IntSize, Gfx::IntRect, Gfx::TextAlignment, Gfx::ColorRole, Gfx::AlignmentRole, Gfx::FlagRole, Gfx::MetricRole, Gfx::PathRole, NonnullRefPtr<Gfx::Bitmap const>, NonnullRefPtr<Gfx::Font const>, GUI::Icon>;
+using VariantUnderlyingType = AK::Variant<Empty, Boolean, float, double, i32, i64, u32, u64, ByteString, Color, Gfx::IntPoint, Gfx::IntSize, Gfx::IntRect, Gfx::TextAlignment, Gfx::ColorRole, Gfx::AlignmentRole, Gfx::FlagRole, Gfx::MetricRole, Gfx::PathRole, NonnullRefPtr<Gfx::Bitmap const>, NonnullRefPtr<Gfx::Font const>, GUI::Icon>;
 }
 
 class Variant : public Detail::VariantUnderlyingType {
@@ -43,15 +43,15 @@ public:
 
     template<typename T>
     Variant(T&& value)
-    requires(IsConstructible<DeprecatedString, T>)
-        : Variant(DeprecatedString(forward<T>(value)))
+    requires(IsConstructible<ByteString, T>)
+        : Variant(ByteString(forward<T>(value)))
     {
     }
     template<typename T>
     Variant& operator=(T&& v)
-    requires(IsConstructible<DeprecatedString, T>)
+    requires(IsConstructible<ByteString, T>)
     {
-        set(DeprecatedString(v));
+        set(ByteString(v));
         return *this;
     }
 
@@ -77,7 +77,7 @@ public:
     bool is_u64() const { return has<u64>(); }
     bool is_float() const { return has<float>(); }
     bool is_double() const { return has<double>(); }
-    bool is_string() const { return has<DeprecatedString>(); }
+    bool is_string() const { return has<ByteString>(); }
     bool is_bitmap() const { return has<NonnullRefPtr<Gfx::Bitmap const>>(); }
     bool is_color() const { return has<Color>(); }
     bool is_icon() const { return has<GUI::Icon>(); }
@@ -103,7 +103,7 @@ public:
             [](Gfx::IntPoint const& v) { return !v.is_zero(); },
             [](OneOf<Gfx::IntRect, Gfx::IntSize> auto const& v) { return !v.is_empty(); },
             [](Enum auto const&) { return true; },
-            [](OneOf<float, double, DeprecatedString, Color, NonnullRefPtr<Gfx::Font const>, NonnullRefPtr<Gfx::Bitmap const>, GUI::Icon> auto const&) { return true; });
+            [](OneOf<float, double, ByteString, Color, NonnullRefPtr<Gfx::Font const>, NonnullRefPtr<Gfx::Bitmap const>, GUI::Icon> auto const&) { return true; });
     }
 
     i32 as_i32() const { return get<i32>(); }
@@ -119,7 +119,7 @@ public:
             [](Integral auto v) { return static_cast<T>(v); },
             [](FloatingPoint auto v) { return (T)v; },
             [](Detail::Boolean v) -> T { return v.value ? 1 : 0; },
-            [](DeprecatedString const& v) {
+            [](ByteString const& v) {
                 if constexpr (IsUnsigned<T>)
                     return v.to_uint<T>().value_or(0u);
                 else
@@ -144,7 +144,7 @@ public:
     Gfx::IntPoint as_point() const { return get<Gfx::IntPoint>(); }
     Gfx::IntSize as_size() const { return get<Gfx::IntSize>(); }
     Gfx::IntRect as_rect() const { return get<Gfx::IntRect>(); }
-    DeprecatedString as_string() const { return get<DeprecatedString>(); }
+    ByteString as_string() const { return get<ByteString>(); }
     Gfx::Bitmap const& as_bitmap() const { return *get<NonnullRefPtr<Gfx::Bitmap const>>(); }
     GUI::Icon as_icon() const { return get<GUI::Icon>(); }
     Color as_color() const { return get<Color>(); }
@@ -196,27 +196,27 @@ public:
     {
         if (auto const* p = get_pointer<Color>())
             return *p;
-        if (auto const* p = get_pointer<DeprecatedString>())
+        if (auto const* p = get_pointer<ByteString>())
             return Color::from_string(*p).value_or(default_value);
         return default_value;
     }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
         return visit(
-            [](Empty) -> DeprecatedString { return "[null]"; },
-            [](DeprecatedString v) { return v; },
-            [](Gfx::TextAlignment v) { return DeprecatedString::formatted("Gfx::TextAlignment::{}", Gfx::to_string(v)); },
-            [](Gfx::ColorRole v) { return DeprecatedString::formatted("Gfx::ColorRole::{}", Gfx::to_string(v)); },
-            [](Gfx::AlignmentRole v) { return DeprecatedString::formatted("Gfx::AlignmentRole::{}", Gfx::to_string(v)); },
-            [](Gfx::FlagRole v) { return DeprecatedString::formatted("Gfx::FlagRole::{}", Gfx::to_string(v)); },
-            [](Gfx::MetricRole v) { return DeprecatedString::formatted("Gfx::MetricRole::{}", Gfx::to_string(v)); },
-            [](Gfx::PathRole v) { return DeprecatedString::formatted("Gfx::PathRole::{}", Gfx::to_string(v)); },
-            [](NonnullRefPtr<Gfx::Font const> const& font) { return DeprecatedString::formatted("[Font: {}]", font->name()); },
-            [](NonnullRefPtr<Gfx::Bitmap const> const&) -> DeprecatedString { return "[Gfx::Bitmap]"; },
-            [](GUI::Icon const&) -> DeprecatedString { return "[GUI::Icon]"; },
-            [](Detail::Boolean v) { return DeprecatedString::formatted("{}", v.value); },
-            [](auto const& v) { return DeprecatedString::formatted("{}", v); });
+            [](Empty) -> ByteString { return "[null]"; },
+            [](ByteString v) { return v; },
+            [](Gfx::TextAlignment v) { return ByteString::formatted("Gfx::TextAlignment::{}", Gfx::to_string(v)); },
+            [](Gfx::ColorRole v) { return ByteString::formatted("Gfx::ColorRole::{}", Gfx::to_string(v)); },
+            [](Gfx::AlignmentRole v) { return ByteString::formatted("Gfx::AlignmentRole::{}", Gfx::to_string(v)); },
+            [](Gfx::FlagRole v) { return ByteString::formatted("Gfx::FlagRole::{}", Gfx::to_string(v)); },
+            [](Gfx::MetricRole v) { return ByteString::formatted("Gfx::MetricRole::{}", Gfx::to_string(v)); },
+            [](Gfx::PathRole v) { return ByteString::formatted("Gfx::PathRole::{}", Gfx::to_string(v)); },
+            [](NonnullRefPtr<Gfx::Font const> const& font) { return ByteString::formatted("[Font: {}]", font->name()); },
+            [](NonnullRefPtr<Gfx::Bitmap const> const&) -> ByteString { return "[Gfx::Bitmap]"; },
+            [](GUI::Icon const&) -> ByteString { return "[GUI::Icon]"; },
+            [](Detail::Boolean v) { return ByteString::formatted("{}", v.value); },
+            [](auto const& v) { return ByteString::formatted("{}", v); });
     }
 
     bool operator==(Variant const&) const;
diff --git a/Userland/Libraries/LibGUI/VimEditingEngine.cpp b/Userland/Libraries/LibGUI/VimEditingEngine.cpp
index a5fd8ad1857..bcc1dea1523 100644
--- a/Userland/Libraries/LibGUI/VimEditingEngine.cpp
+++ b/Userland/Libraries/LibGUI/VimEditingEngine.cpp
@@ -1482,14 +1482,14 @@ void VimEditingEngine::put_before()
             sb.append(m_yank_buffer);
             sb.append_code_point(0x0A);
         }
-        m_editor->insert_at_cursor_or_replace_selection(sb.to_deprecated_string());
+        m_editor->insert_at_cursor_or_replace_selection(sb.to_byte_string());
         m_editor->set_cursor({ m_editor->cursor().line(), m_editor->current_line().first_non_whitespace_column() });
     } else {
         StringBuilder sb = StringBuilder(m_yank_buffer.length() * amount);
         for (auto i = 0; i < amount; i++) {
             sb.append(m_yank_buffer);
         }
-        m_editor->insert_at_cursor_or_replace_selection(sb.to_deprecated_string());
+        m_editor->insert_at_cursor_or_replace_selection(sb.to_byte_string());
         move_one_left();
     }
 }
@@ -1505,7 +1505,7 @@ void VimEditingEngine::put_after()
             sb.append_code_point(0x0A);
             sb.append(m_yank_buffer);
         }
-        m_editor->insert_at_cursor_or_replace_selection(sb.to_deprecated_string());
+        m_editor->insert_at_cursor_or_replace_selection(sb.to_byte_string());
         m_editor->set_cursor({ m_editor->cursor().line(), m_editor->current_line().first_non_whitespace_column() });
     } else {
         // FIXME: If attempting to put on the last column a line,
@@ -1515,7 +1515,7 @@ void VimEditingEngine::put_after()
         for (auto i = 0; i < amount; i++) {
             sb.append(m_yank_buffer);
         }
-        m_editor->insert_at_cursor_or_replace_selection(sb.to_deprecated_string());
+        m_editor->insert_at_cursor_or_replace_selection(sb.to_byte_string());
         move_one_left();
     }
 }
diff --git a/Userland/Libraries/LibGUI/VimEditingEngine.h b/Userland/Libraries/LibGUI/VimEditingEngine.h
index 84bfa848456..64f8faabb82 100644
--- a/Userland/Libraries/LibGUI/VimEditingEngine.h
+++ b/Userland/Libraries/LibGUI/VimEditingEngine.h
@@ -170,7 +170,7 @@ private:
     VimMotion m_motion;
 
     YankType m_yank_type {};
-    DeprecatedString m_yank_buffer {};
+    ByteString m_yank_buffer {};
     void yank(YankType);
     void yank(TextRange, YankType yank_type);
     void put_before();
diff --git a/Userland/Libraries/LibGUI/Widget.cpp b/Userland/Libraries/LibGUI/Widget.cpp
index bf79dd77537..32a72a3d794 100644
--- a/Userland/Libraries/LibGUI/Widget.cpp
+++ b/Userland/Libraries/LibGUI/Widget.cpp
@@ -92,11 +92,11 @@ Widget::Widget()
     register_property(
         "font_type", [this] { return m_font->is_fixed_width() ? "FixedWidth" : "Normal"; },
         [this](auto& value) {
-            if (value.to_deprecated_string() == "FixedWidth") {
+            if (value.to_byte_string() == "FixedWidth") {
                 set_font_fixed_width(true);
                 return true;
             }
-            if (value.to_deprecated_string() == "Normal") {
+            if (value.to_byte_string() == "Normal") {
                 set_font_fixed_width(false);
                 return true;
             }
@@ -138,9 +138,9 @@ Widget::Widget()
         });
 
     register_property(
-        "foreground_color", [this]() -> JsonValue { return palette().color(foreground_role()).to_deprecated_string(); },
+        "foreground_color", [this]() -> JsonValue { return palette().color(foreground_role()).to_byte_string(); },
         [this](auto& value) {
-            auto c = Color::from_string(value.to_deprecated_string());
+            auto c = Color::from_string(value.to_byte_string());
             if (c.has_value()) {
                 auto _palette = palette();
                 _palette.set_color(foreground_role(), c.value());
@@ -151,9 +151,9 @@ Widget::Widget()
         });
 
     register_property(
-        "background_color", [this]() -> JsonValue { return palette().color(background_role()).to_deprecated_string(); },
+        "background_color", [this]() -> JsonValue { return palette().color(background_role()).to_byte_string(); },
         [this](JsonValue const& value) {
-            auto color_str = String::from_deprecated_string(value.to_deprecated_string());
+            auto color_str = String::from_byte_string(value.to_byte_string());
             if (color_str.is_error())
                 return false;
 
@@ -1084,7 +1084,7 @@ void Widget::set_foreground_role(ColorRole role)
 
 bool Widget::set_background_color(String color_str)
 {
-    auto color = Color::from_string(color_str.to_deprecated_string());
+    auto color = Color::from_string(color_str.to_byte_string());
     if (!color.has_value())
         return false;
     set_background_color(color.release_value());
@@ -1188,12 +1188,12 @@ ErrorOr<void> Widget::load_from_gml_ast(NonnullRefPtr<GUI::GML::Node const> ast,
         if (auto* registration = GUI::ObjectClassRegistration::find(class_name)) {
             auto layout = TRY(registration->construct());
             if (!registration->is_derived_from(layout_class)) {
-                dbgln("Invalid layout class: '{}'", class_name.to_deprecated_string());
+                dbgln("Invalid layout class: '{}'", class_name.to_byte_string());
                 return Error::from_string_literal("Invalid layout class");
             }
             set_layout(static_ptr_cast<Layout>(layout));
         } else {
-            dbgln("Unknown layout class: '{}'", class_name.to_deprecated_string());
+            dbgln("Unknown layout class: '{}'", class_name.to_byte_string());
             return Error::from_string_literal("Unknown layout class");
         }
 
diff --git a/Userland/Libraries/LibGUI/Widget.h b/Userland/Libraries/LibGUI/Widget.h
index e7311e71993..f3f492ec45b 100644
--- a/Userland/Libraries/LibGUI/Widget.h
+++ b/Userland/Libraries/LibGUI/Widget.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/EnumBits.h>
 #include <AK/JsonObject.h>
 #include <AK/NonnullRefPtr.h>
@@ -424,7 +424,7 @@ private:
     int dummy_fixed_height() { return 0; }
     Gfx::IntSize dummy_fixed_size() { return {}; }
 
-    // HACK: Used as property getter for the font_family property, can be removed when Font is migrated from DeprecatedString.
+    // HACK: Used as property getter for the font_family property, can be removed when Font is migrated from ByteString.
     String font_family() const;
 
     Window* m_window { nullptr };
diff --git a/Userland/Libraries/LibGUI/Window.cpp b/Userland/Libraries/LibGUI/Window.cpp
index 9210e60a166..f050cc2886b 100644
--- a/Userland/Libraries/LibGUI/Window.cpp
+++ b/Userland/Libraries/LibGUI/Window.cpp
@@ -89,7 +89,7 @@ Window::Window(Core::EventReceiver* parent)
         "title",
         [this] { return title(); },
         [this](auto& value) {
-            set_title(value.to_deprecated_string());
+            set_title(value.to_byte_string());
             return true;
         });
 
@@ -247,7 +247,7 @@ void Window::hide()
     }
 }
 
-void Window::set_title(DeprecatedString title)
+void Window::set_title(ByteString title)
 {
     m_title_when_windowless = move(title);
     if (!is_visible())
@@ -255,7 +255,7 @@ void Window::set_title(DeprecatedString title)
     ConnectionToWindowServer::the().async_set_window_title(m_window_id, m_title_when_windowless);
 }
 
-DeprecatedString Window::title() const
+ByteString Window::title() const
 {
     if (!is_visible())
         return m_title_when_windowless;
diff --git a/Userland/Libraries/LibGUI/Window.h b/Userland/Libraries/LibGUI/Window.h
index f53b7ca76d0..855647844e7 100644
--- a/Userland/Libraries/LibGUI/Window.h
+++ b/Userland/Libraries/LibGUI/Window.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Function.h>
 #include <AK/NonnullOwnPtr.h>
@@ -89,8 +89,8 @@ public:
 
     void make_window_manager(unsigned event_mask);
 
-    DeprecatedString title() const;
-    void set_title(DeprecatedString);
+    ByteString title() const;
+    void set_title(ByteString);
 
     enum class CloseRequestDecision {
         StayOpen,
@@ -302,7 +302,7 @@ private:
     Gfx::IntRect m_rect_when_windowless;
     Gfx::IntSize m_minimum_size_when_windowless { 0, 0 };
     Gfx::IntRect m_floating_rect;
-    DeprecatedString m_title_when_windowless;
+    ByteString m_title_when_windowless;
     Vector<Gfx::IntRect, 32> m_pending_paint_event_rects;
     Gfx::IntSize m_size_increment;
     Gfx::IntSize m_base_size;
diff --git a/Userland/Libraries/LibGemini/Document.cpp b/Userland/Libraries/LibGemini/Document.cpp
index 2e89dc233a0..df43088374e 100644
--- a/Userland/Libraries/LibGemini/Document.cpp
+++ b/Userland/Libraries/LibGemini/Document.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/StringBuilder.h>
@@ -13,7 +13,7 @@
 
 namespace Gemini {
 
-DeprecatedString Document::render_to_html() const
+ByteString Document::render_to_html() const
 {
     StringBuilder html_builder;
     html_builder.append("<!DOCTYPE html>\n<html>\n"sv);
@@ -26,7 +26,7 @@ DeprecatedString Document::render_to_html() const
     }
     html_builder.append("</body>"sv);
     html_builder.append("</html>"sv);
-    return html_builder.to_deprecated_string();
+    return html_builder.to_byte_string();
 }
 
 NonnullRefPtr<Document> Document::parse(StringView lines, const URL& url)
diff --git a/Userland/Libraries/LibGemini/Document.h b/Userland/Libraries/LibGemini/Document.h
index 488a5ccf11b..d7957a98f9f 100644
--- a/Userland/Libraries/LibGemini/Document.h
+++ b/Userland/Libraries/LibGemini/Document.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/URL.h>
@@ -15,22 +15,22 @@ namespace Gemini {
 
 class Line {
 public:
-    Line(DeprecatedString string)
+    Line(ByteString string)
         : m_text(move(string))
     {
     }
 
     virtual ~Line() = default;
 
-    virtual DeprecatedString render_to_html() const = 0;
+    virtual ByteString render_to_html() const = 0;
 
 protected:
-    DeprecatedString m_text;
+    ByteString m_text;
 };
 
 class Document : public RefCounted<Document> {
 public:
-    DeprecatedString render_to_html() const;
+    ByteString render_to_html() const;
 
     static NonnullRefPtr<Document> parse(StringView source, const URL&);
 
@@ -52,43 +52,43 @@ private:
 
 class Text : public Line {
 public:
-    Text(DeprecatedString line)
+    Text(ByteString line)
         : Line(move(line))
     {
     }
     virtual ~Text() override = default;
-    virtual DeprecatedString render_to_html() const override;
+    virtual ByteString render_to_html() const override;
 };
 
 class Link : public Line {
 public:
-    Link(DeprecatedString line, Document const&);
+    Link(ByteString line, Document const&);
     virtual ~Link() override = default;
-    virtual DeprecatedString render_to_html() const override;
+    virtual ByteString render_to_html() const override;
 
 private:
     URL m_url;
-    DeprecatedString m_name;
+    ByteString m_name;
 };
 
 class Preformatted : public Line {
 public:
-    Preformatted(DeprecatedString line)
+    Preformatted(ByteString line)
         : Line(move(line))
     {
     }
     virtual ~Preformatted() override = default;
-    virtual DeprecatedString render_to_html() const override;
+    virtual ByteString render_to_html() const override;
 };
 
 class UnorderedList : public Line {
 public:
-    UnorderedList(DeprecatedString line)
+    UnorderedList(ByteString line)
         : Line(move(line))
     {
     }
     virtual ~UnorderedList() override = default;
-    virtual DeprecatedString render_to_html() const override;
+    virtual ByteString render_to_html() const override;
 };
 
 class Control : public Line {
@@ -105,7 +105,7 @@ public:
     {
     }
     virtual ~Control() override = default;
-    virtual DeprecatedString render_to_html() const override;
+    virtual ByteString render_to_html() const override;
 
 private:
     Kind m_kind;
@@ -113,13 +113,13 @@ private:
 
 class Heading : public Line {
 public:
-    Heading(DeprecatedString line, int level)
+    Heading(ByteString line, int level)
         : Line(move(line))
         , m_level(level)
     {
     }
     virtual ~Heading() override = default;
-    virtual DeprecatedString render_to_html() const override;
+    virtual ByteString render_to_html() const override;
 
 private:
     int m_level { 1 };
diff --git a/Userland/Libraries/LibGemini/GeminiRequest.cpp b/Userland/Libraries/LibGemini/GeminiRequest.cpp
index a66cdb8942e..ea59f8a06dd 100644
--- a/Userland/Libraries/LibGemini/GeminiRequest.cpp
+++ b/Userland/Libraries/LibGemini/GeminiRequest.cpp
@@ -13,7 +13,7 @@ namespace Gemini {
 ErrorOr<ByteBuffer> GeminiRequest::to_raw_request() const
 {
     StringBuilder builder;
-    TRY(builder.try_append(m_url.to_deprecated_string()));
+    TRY(builder.try_append(m_url.to_byte_string()));
     TRY(builder.try_append("\r\n"sv));
     return builder.to_byte_buffer();
 }
diff --git a/Userland/Libraries/LibGemini/GeminiResponse.cpp b/Userland/Libraries/LibGemini/GeminiResponse.cpp
index cf93faca331..9000e2b3f61 100644
--- a/Userland/Libraries/LibGemini/GeminiResponse.cpp
+++ b/Userland/Libraries/LibGemini/GeminiResponse.cpp
@@ -8,7 +8,7 @@
 
 namespace Gemini {
 
-GeminiResponse::GeminiResponse(int status, DeprecatedString meta)
+GeminiResponse::GeminiResponse(int status, ByteString meta)
     : m_status(status)
     , m_meta(meta)
 {
diff --git a/Userland/Libraries/LibGemini/GeminiResponse.h b/Userland/Libraries/LibGemini/GeminiResponse.h
index 89afc62ee33..67dfcf4741c 100644
--- a/Userland/Libraries/LibGemini/GeminiResponse.h
+++ b/Userland/Libraries/LibGemini/GeminiResponse.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/NetworkResponse.h>
 
 namespace Gemini {
@@ -14,19 +14,19 @@ namespace Gemini {
 class GeminiResponse : public Core::NetworkResponse {
 public:
     virtual ~GeminiResponse() override = default;
-    static NonnullRefPtr<GeminiResponse> create(int status, DeprecatedString meta)
+    static NonnullRefPtr<GeminiResponse> create(int status, ByteString meta)
     {
         return adopt_ref(*new GeminiResponse(status, meta));
     }
 
     int status() const { return m_status; }
-    DeprecatedString meta() const { return m_meta; }
+    ByteString meta() const { return m_meta; }
 
 private:
-    GeminiResponse(int status, DeprecatedString);
+    GeminiResponse(int status, ByteString);
 
     int m_status { 0 };
-    DeprecatedString m_meta;
+    ByteString m_meta;
 };
 
 }
diff --git a/Userland/Libraries/LibGemini/Job.cpp b/Userland/Libraries/LibGemini/Job.cpp
index 4281fb9d928..39f5243c704 100644
--- a/Userland/Libraries/LibGemini/Job.cpp
+++ b/Userland/Libraries/LibGemini/Job.cpp
@@ -115,7 +115,7 @@ void Job::on_socket_connected()
 
     if constexpr (JOB_DEBUG) {
         dbgln("Job: raw_request:");
-        dbgln("{}", DeprecatedString::copy(raw_request));
+        dbgln("{}", ByteString::copy(raw_request));
     }
     bool success = write(raw_request);
     if (!success)
diff --git a/Userland/Libraries/LibGemini/Job.h b/Userland/Libraries/LibGemini/Job.h
index 9df185ee385..c5eb28cd2e0 100644
--- a/Userland/Libraries/LibGemini/Job.h
+++ b/Userland/Libraries/LibGemini/Job.h
@@ -53,7 +53,7 @@ protected:
     GeminiRequest m_request;
     State m_state { State::InStatus };
     int m_status { -1 };
-    DeprecatedString m_meta;
+    ByteString m_meta;
     Vector<ByteBuffer, 2> m_received_buffers;
     size_t m_received_size { 0 };
     size_t m_buffered_size { 0 };
diff --git a/Userland/Libraries/LibGemini/Line.cpp b/Userland/Libraries/LibGemini/Line.cpp
index 861690343cf..230ca344a76 100644
--- a/Userland/Libraries/LibGemini/Line.cpp
+++ b/Userland/Libraries/LibGemini/Line.cpp
@@ -9,20 +9,20 @@
 
 namespace Gemini {
 
-DeprecatedString Text::render_to_html() const
+ByteString Text::render_to_html() const
 {
     StringBuilder builder;
     builder.append(escape_html_entities(m_text));
     builder.append("<br>\n"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Heading::render_to_html() const
+ByteString Heading::render_to_html() const
 {
-    return DeprecatedString::formatted("<h{}>{}</h{}>", m_level, escape_html_entities(m_text.substring_view(m_level, m_text.length() - m_level)), m_level);
+    return ByteString::formatted("<h{}>{}</h{}>", m_level, escape_html_entities(m_text.substring_view(m_level, m_text.length() - m_level)), m_level);
 }
 
-DeprecatedString UnorderedList::render_to_html() const
+ByteString UnorderedList::render_to_html() const
 {
     // 1.3.5.4.2 "Advanced clients can take the space of the bullet symbol into account"
     //           FIXME: The spec is unclear about what the space means, or where it goes
@@ -31,10 +31,10 @@ DeprecatedString UnorderedList::render_to_html() const
     builder.append("<li>"sv);
     builder.append(escape_html_entities(m_text.substring_view(1, m_text.length() - 1)));
     builder.append("</li>"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Control::render_to_html() const
+ByteString Control::render_to_html() const
 {
     switch (m_kind) {
     case Kind::PreformattedEnd:
@@ -52,7 +52,7 @@ DeprecatedString Control::render_to_html() const
     }
 }
 
-Link::Link(DeprecatedString text, Document const& document)
+Link::Link(ByteString text, Document const& document)
     : Line(move(text))
 {
     size_t index = 2;
@@ -60,7 +60,7 @@ Link::Link(DeprecatedString text, Document const& document)
         ++index;
     auto url_string = m_text.substring_view(index, m_text.length() - index);
     auto space_offset = url_string.find_any_of(" \t"sv);
-    DeprecatedString url = url_string;
+    ByteString url = url_string;
     if (space_offset.has_value()) {
         url = url_string.substring_view(0, space_offset.value());
         auto offset = space_offset.value();
@@ -70,27 +70,27 @@ Link::Link(DeprecatedString text, Document const& document)
     }
     m_url = document.url().complete_url(url);
     if (m_name.is_empty())
-        m_name = m_url.to_deprecated_string();
+        m_name = m_url.to_byte_string();
 }
 
-DeprecatedString Link::render_to_html() const
+ByteString Link::render_to_html() const
 {
     StringBuilder builder;
     builder.append("<a href=\""sv);
-    builder.append(escape_html_entities(m_url.to_deprecated_string()));
+    builder.append(escape_html_entities(m_url.to_byte_string()));
     builder.append("\">"sv);
     builder.append(escape_html_entities(m_name));
     builder.append("</a><br>\n"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Preformatted::render_to_html() const
+ByteString Preformatted::render_to_html() const
 {
     StringBuilder builder;
     builder.append(escape_html_entities(m_text));
     builder.append('\n');
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/Userland/Libraries/LibGfx/Bitmap.cpp b/Userland/Libraries/LibGfx/Bitmap.cpp
index de51a432430..e2ecdc0569b 100644
--- a/Userland/Libraries/LibGfx/Bitmap.cpp
+++ b/Userland/Libraries/LibGfx/Bitmap.cpp
@@ -6,8 +6,8 @@
  */
 
 #include <AK/Bitmap.h>
+#include <AK/ByteString.h>
 #include <AK/Checked.h>
-#include <AK/DeprecatedString.h>
 #include <AK/LexicalPath.h>
 #include <AK/Memory.h>
 #include <AK/MemoryStream.h>
@@ -145,7 +145,7 @@ ErrorOr<NonnullRefPtr<Bitmap>> Bitmap::load_from_file(NonnullOwnPtr<Core::File>
     return load_from_bytes(mapped_file->bytes(), ideal_size, mime_type);
 }
 
-ErrorOr<NonnullRefPtr<Bitmap>> Bitmap::load_from_bytes(ReadonlyBytes bytes, Optional<IntSize> ideal_size, Optional<DeprecatedString> mine_type)
+ErrorOr<NonnullRefPtr<Bitmap>> Bitmap::load_from_bytes(ReadonlyBytes bytes, Optional<IntSize> ideal_size, Optional<ByteString> mine_type)
 {
     if (auto decoder = ImageDecoder::try_create_for_raw_bytes(bytes, mine_type)) {
         auto frame = TRY(decoder->frame(0, ideal_size));
@@ -552,7 +552,7 @@ void Bitmap::strip_alpha_channel()
     m_format = BitmapFormat::BGRx8888;
 }
 
-void Bitmap::set_mmap_name([[maybe_unused]] DeprecatedString const& name)
+void Bitmap::set_mmap_name([[maybe_unused]] ByteString const& name)
 {
     VERIFY(m_needs_munmap);
 #ifdef AK_OS_SERENITY
@@ -624,7 +624,7 @@ ErrorOr<BackingStore> Bitmap::allocate_backing_store(BitmapFormat format, IntSiz
     int map_flags = MAP_ANONYMOUS | MAP_PRIVATE;
 #ifdef AK_OS_SERENITY
     map_flags |= MAP_PURGEABLE;
-    void* data = mmap_with_name(nullptr, data_size_in_bytes, PROT_READ | PROT_WRITE, map_flags, 0, 0, DeprecatedString::formatted("GraphicsBitmap [{}]", size).characters());
+    void* data = mmap_with_name(nullptr, data_size_in_bytes, PROT_READ | PROT_WRITE, map_flags, 0, 0, ByteString::formatted("GraphicsBitmap [{}]", size).characters());
 #else
     void* data = mmap(nullptr, data_size_in_bytes, PROT_READ | PROT_WRITE, map_flags, -1, 0);
 #endif
diff --git a/Userland/Libraries/LibGfx/Bitmap.h b/Userland/Libraries/LibGfx/Bitmap.h
index 33afb3fe62f..120f7db2544 100644
--- a/Userland/Libraries/LibGfx/Bitmap.h
+++ b/Userland/Libraries/LibGfx/Bitmap.h
@@ -95,7 +95,7 @@ public:
     [[nodiscard]] static ErrorOr<NonnullRefPtr<Bitmap>> create_wrapper(BitmapFormat, IntSize, int intrinsic_scale, size_t pitch, void*);
     [[nodiscard]] static ErrorOr<NonnullRefPtr<Bitmap>> load_from_file(StringView path, int scale_factor = 1, Optional<IntSize> ideal_size = {});
     [[nodiscard]] static ErrorOr<NonnullRefPtr<Bitmap>> load_from_file(NonnullOwnPtr<Core::File>, StringView path, Optional<IntSize> ideal_size = {});
-    [[nodiscard]] static ErrorOr<NonnullRefPtr<Bitmap>> load_from_bytes(ReadonlyBytes, Optional<IntSize> ideal_size = {}, Optional<DeprecatedString> mine_type = {});
+    [[nodiscard]] static ErrorOr<NonnullRefPtr<Bitmap>> load_from_bytes(ReadonlyBytes, Optional<IntSize> ideal_size = {}, Optional<ByteString> mine_type = {});
     [[nodiscard]] static ErrorOr<NonnullRefPtr<Bitmap>> create_with_anonymous_buffer(BitmapFormat, Core::AnonymousBuffer, IntSize, int intrinsic_scale);
     static ErrorOr<NonnullRefPtr<Bitmap>> create_from_serialized_bytes(ReadonlyBytes);
     static ErrorOr<NonnullRefPtr<Bitmap>> create_from_serialized_byte_buffer(ByteBuffer&&);
@@ -197,7 +197,7 @@ public:
     // Call only for BGRx8888 and BGRA8888 bitmaps.
     void strip_alpha_channel();
 
-    void set_mmap_name(DeprecatedString const&);
+    void set_mmap_name(ByteString const&);
 
     [[nodiscard]] static constexpr size_t size_in_bytes(size_t pitch, int physical_height) { return pitch * physical_height; }
     [[nodiscard]] size_t size_in_bytes() const { return size_in_bytes(m_pitch, physical_height()); }
diff --git a/Userland/Libraries/LibGfx/Color.cpp b/Userland/Libraries/LibGfx/Color.cpp
index 61c8ba37a89..8b059498f64 100644
--- a/Userland/Libraries/LibGfx/Color.cpp
+++ b/Userland/Libraries/LibGfx/Color.cpp
@@ -6,7 +6,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/FloatingPointStringConversions.h>
 #include <AK/Optional.h>
 #include <AK/Vector.h>
@@ -28,14 +28,14 @@ String Color::to_string_without_alpha() const
     return MUST(String::formatted("#{:02x}{:02x}{:02x}", red(), green(), blue()));
 }
 
-DeprecatedString Color::to_deprecated_string() const
+ByteString Color::to_byte_string() const
 {
-    return to_string().to_deprecated_string();
+    return to_string().to_byte_string();
 }
 
-DeprecatedString Color::to_deprecated_string_without_alpha() const
+ByteString Color::to_byte_string_without_alpha() const
 {
-    return to_string_without_alpha().to_deprecated_string();
+    return to_string_without_alpha().to_byte_string();
 }
 
 static Optional<Color> parse_rgb_color(StringView string)
@@ -373,5 +373,5 @@ ErrorOr<Gfx::Color> IPC::decode(Decoder& decoder)
 
 ErrorOr<void> AK::Formatter<Gfx::Color>::format(FormatBuilder& builder, Gfx::Color value)
 {
-    return Formatter<StringView>::format(builder, value.to_deprecated_string());
+    return Formatter<StringView>::format(builder, value.to_byte_string());
 }
diff --git a/Userland/Libraries/LibGfx/Color.h b/Userland/Libraries/LibGfx/Color.h
index d0526bdb26d..827b37175f7 100644
--- a/Userland/Libraries/LibGfx/Color.h
+++ b/Userland/Libraries/LibGfx/Color.h
@@ -359,8 +359,8 @@ public:
     String to_string() const;
     String to_string_without_alpha() const;
 
-    DeprecatedString to_deprecated_string() const;
-    DeprecatedString to_deprecated_string_without_alpha() const;
+    ByteString to_byte_string() const;
+    ByteString to_byte_string_without_alpha() const;
     static Optional<Color> from_string(StringView);
     static Optional<Color> from_named_css_color_string(StringView);
 
diff --git a/Userland/Libraries/LibGfx/Font/BitmapFont.cpp b/Userland/Libraries/LibGfx/Font/BitmapFont.cpp
index 5251e459f2c..a025885e71b 100644
--- a/Userland/Libraries/LibGfx/Font/BitmapFont.cpp
+++ b/Userland/Libraries/LibGfx/Font/BitmapFont.cpp
@@ -248,7 +248,7 @@ ErrorOr<NonnullRefPtr<BitmapFont>> BitmapFont::try_load_from_uri(StringView uri)
     return try_load_from_resource(TRY(Core::Resource::load_from_uri(uri)));
 }
 
-ErrorOr<void> BitmapFont::write_to_file(DeprecatedString const& path)
+ErrorOr<void> BitmapFont::write_to_file(ByteString const& path)
 {
     auto stream = TRY(Core::File::open(path, Core::File::OpenMode::Write));
     TRY(write_to_file(move(stream)));
diff --git a/Userland/Libraries/LibGfx/Font/BitmapFont.h b/Userland/Libraries/LibGfx/Font/BitmapFont.h
index 60b6f794be3..266ff2e1d61 100644
--- a/Userland/Libraries/LibGfx/Font/BitmapFont.h
+++ b/Userland/Libraries/LibGfx/Font/BitmapFont.h
@@ -6,8 +6,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/RefCounted.h>
 #include <AK/RefPtr.h>
 #include <AK/Types.h>
@@ -36,7 +36,7 @@ public:
     static ErrorOr<NonnullRefPtr<BitmapFont>> try_load_from_mapped_file(NonnullOwnPtr<Core::MappedFile>);
     static ErrorOr<NonnullRefPtr<BitmapFont>> try_load_from_stream(FixedMemoryStream&);
 
-    ErrorOr<void> write_to_file(DeprecatedString const& path);
+    ErrorOr<void> write_to_file(ByteString const& path);
     ErrorOr<void> write_to_file(NonnullOwnPtr<Core::File> file);
 
     ~BitmapFont();
diff --git a/Userland/Libraries/LibGfx/Font/FontDatabase.cpp b/Userland/Libraries/LibGfx/Font/FontDatabase.cpp
index ea3d880eca5..5dc42dbf150 100644
--- a/Userland/Libraries/LibGfx/Font/FontDatabase.cpp
+++ b/Userland/Libraries/LibGfx/Font/FontDatabase.cpp
@@ -26,15 +26,15 @@ FontDatabase& FontDatabase::the()
 }
 
 static RefPtr<Font> s_default_font;
-static DeprecatedString s_default_font_query;
+static ByteString s_default_font_query;
 
 static RefPtr<Font> s_window_title_font;
-static DeprecatedString s_window_title_font_query;
+static ByteString s_window_title_font_query;
 
 static RefPtr<Font> s_fixed_width_font;
-static DeprecatedString s_fixed_width_font_query;
+static ByteString s_fixed_width_font_query;
 
-void FontDatabase::set_default_font_query(DeprecatedString query)
+void FontDatabase::set_default_font_query(ByteString query)
 {
     if (s_default_font_query == query)
         return;
@@ -42,12 +42,12 @@ void FontDatabase::set_default_font_query(DeprecatedString query)
     s_default_font = nullptr;
 }
 
-DeprecatedString FontDatabase::default_font_query()
+ByteString FontDatabase::default_font_query()
 {
     return s_default_font_query;
 }
 
-void FontDatabase::set_window_title_font_query(DeprecatedString query)
+void FontDatabase::set_window_title_font_query(ByteString query)
 {
     if (s_window_title_font_query == query)
         return;
@@ -55,7 +55,7 @@ void FontDatabase::set_window_title_font_query(DeprecatedString query)
     s_window_title_font = nullptr;
 }
 
-DeprecatedString FontDatabase::window_title_font_query()
+ByteString FontDatabase::window_title_font_query()
 {
     return s_window_title_font_query;
 }
@@ -80,7 +80,7 @@ Font& FontDatabase::window_title_font()
     return *s_window_title_font;
 }
 
-void FontDatabase::set_fixed_width_font_query(DeprecatedString query)
+void FontDatabase::set_fixed_width_font_query(ByteString query)
 {
     if (s_fixed_width_font_query == query)
         return;
@@ -88,7 +88,7 @@ void FontDatabase::set_fixed_width_font_query(DeprecatedString query)
     s_fixed_width_font = nullptr;
 }
 
-DeprecatedString FontDatabase::fixed_width_font_query()
+ByteString FontDatabase::fixed_width_font_query()
 {
     return s_fixed_width_font_query;
 }
@@ -104,7 +104,7 @@ Font& FontDatabase::default_fixed_width_font()
 }
 
 struct FontDatabase::Private {
-    HashMap<DeprecatedString, NonnullRefPtr<Gfx::Font>, CaseInsensitiveStringTraits> full_name_to_font_map;
+    HashMap<ByteString, NonnullRefPtr<Gfx::Font>, CaseInsensitiveStringTraits> full_name_to_font_map;
     HashMap<FlyString, Vector<NonnullRefPtr<Typeface>>, AK::ASCIICaseInsensitiveFlyStringTraits> typefaces;
 };
 
@@ -122,7 +122,7 @@ void FontDatabase::load_all_fonts_from_uri(StringView uri)
         if (path.has_extension(".font"sv)) {
             if (auto font_or_error = Gfx::BitmapFont::try_load_from_resource(resource); !font_or_error.is_error()) {
                 auto font = font_or_error.release_value();
-                m_private->full_name_to_font_map.set(font->qualified_name().to_deprecated_string(), *font);
+                m_private->full_name_to_font_map.set(font->qualified_name().to_byte_string(), *font);
                 auto typeface = get_or_create_typeface(font->family(), font->variant());
                 typeface->add_bitmap_font(font);
             }
diff --git a/Userland/Libraries/LibGfx/Font/FontDatabase.h b/Userland/Libraries/LibGfx/Font/FontDatabase.h
index cdf0ebbadf3..50780de60e9 100644
--- a/Userland/Libraries/LibGfx/Font/FontDatabase.h
+++ b/Userland/Libraries/LibGfx/Font/FontDatabase.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/FlyString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
@@ -39,14 +39,14 @@ public:
     static Font& default_fixed_width_font();
     static Font& window_title_font();
 
-    static DeprecatedString default_font_query();
-    static DeprecatedString window_title_font_query();
-    static DeprecatedString fixed_width_font_query();
+    static ByteString default_font_query();
+    static ByteString window_title_font_query();
+    static ByteString fixed_width_font_query();
 
-    static DeprecatedString default_fonts_lookup_path();
-    static void set_default_font_query(DeprecatedString);
-    static void set_window_title_font_query(DeprecatedString);
-    static void set_fixed_width_font_query(DeprecatedString);
+    static ByteString default_fonts_lookup_path();
+    static void set_default_font_query(ByteString);
+    static void set_window_title_font_query(ByteString);
+    static void set_fixed_width_font_query(ByteString);
 
     RefPtr<Gfx::Font> get(FlyString const& family, float point_size, unsigned weight, unsigned width, unsigned slope, Font::AllowInexactSizeMatch = Font::AllowInexactSizeMatch::No);
     RefPtr<Gfx::Font> get(FlyString const& family, FlyString const& variant, float point_size, Font::AllowInexactSizeMatch = Font::AllowInexactSizeMatch::No);
diff --git a/Userland/Libraries/LibGfx/Font/OpenType/Tables.h b/Userland/Libraries/LibGfx/Font/OpenType/Tables.h
index 988203f537b..e1edfc2f6c5 100644
--- a/Userland/Libraries/LibGfx/Font/OpenType/Tables.h
+++ b/Userland/Libraries/LibGfx/Font/OpenType/Tables.h
@@ -9,7 +9,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Endian.h>
 #include <AK/Error.h>
 #include <AK/FixedArray.h>
diff --git a/Userland/Libraries/LibGfx/Font/WOFF/Font.h b/Userland/Libraries/LibGfx/Font/WOFF/Font.h
index beae3e1a0b0..84e9bd816f2 100644
--- a/Userland/Libraries/LibGfx/Font/WOFF/Font.h
+++ b/Userland/Libraries/LibGfx/Font/WOFF/Font.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Noncopyable.h>
 #include <AK/OwnPtr.h>
 #include <AK/RefCounted.h>
diff --git a/Userland/Libraries/LibGfx/ICC/Profile.cpp b/Userland/Libraries/LibGfx/ICC/Profile.cpp
index 8028c8b61f8..76c0cc44561 100644
--- a/Userland/Libraries/LibGfx/ICC/Profile.cpp
+++ b/Userland/Libraries/LibGfx/ICC/Profile.cpp
@@ -335,13 +335,13 @@ ErrorOr<void> parse_reserved(ICCHeader const& header)
 
 URL device_manufacturer_url(DeviceManufacturer device_manufacturer)
 {
-    return URL(DeprecatedString::formatted("https://www.color.org/signatureRegistry/?entityEntry={:c}{:c}{:c}{:c}-{:08X}",
+    return URL(ByteString::formatted("https://www.color.org/signatureRegistry/?entityEntry={:c}{:c}{:c}{:c}-{:08X}",
         device_manufacturer.c0(), device_manufacturer.c1(), device_manufacturer.c2(), device_manufacturer.c3(), device_manufacturer.value));
 }
 
 URL device_model_url(DeviceModel device_model)
 {
-    return URL(DeprecatedString::formatted("https://www.color.org/signatureRegistry/deviceRegistry/?entityEntry={:c}{:c}{:c}{:c}-{:08X}",
+    return URL(ByteString::formatted("https://www.color.org/signatureRegistry/deviceRegistry/?entityEntry={:c}{:c}{:c}{:c}-{:08X}",
         device_model.c0(), device_model.c1(), device_model.c2(), device_model.c3(), device_model.value));
 }
 
diff --git a/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.cpp
index 86bd6b32a8e..f5b8e0bda1f 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/BMPLoader.cpp
@@ -6,8 +6,8 @@
  */
 
 #include <AK/BuiltinWrappers.h>
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Error.h>
 #include <AK/Function.h>
 #include <AK/Try.h>
@@ -82,7 +82,7 @@ template<typename T>
 struct Formatter<Gfx::Endpoint<T>> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, Gfx::Endpoint<T> const& value)
     {
-        return Formatter<StringView>::format(builder, DeprecatedString::formatted("({}, {}, {})", value.x, value.y, value.z));
+        return Formatter<StringView>::format(builder, ByteString::formatted("({}, {}, {})", value.x, value.y, value.z));
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/ImageFormats/DDSLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/DDSLoader.cpp
index c3890b6bc93..05f878c41b9 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/DDSLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/DDSLoader.cpp
@@ -622,7 +622,7 @@ void DDSLoadingContext::dump_debug()
         builder.append(" DDS_ALPHA_MODE_CUSTOM"sv);
     builder.append("\n"sv);
 
-    dbgln("{}", builder.to_deprecated_string());
+    dbgln("{}", builder.to_byte_string());
 }
 
 DDSImageDecoderPlugin::DDSImageDecoderPlugin(FixedMemoryStream stream)
diff --git a/Userland/Libraries/LibGfx/ImageFormats/ImageDecoder.cpp b/Userland/Libraries/LibGfx/ImageFormats/ImageDecoder.cpp
index 5a5551baac9..5d1bd80c703 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/ImageDecoder.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/ImageDecoder.cpp
@@ -86,7 +86,7 @@ static OwnPtr<ImageDecoderPlugin> probe_and_sniff_for_appropriate_plugin_with_kn
     return {};
 }
 
-RefPtr<ImageDecoder> ImageDecoder::try_create_for_raw_bytes(ReadonlyBytes bytes, Optional<DeprecatedString> mime_type)
+RefPtr<ImageDecoder> ImageDecoder::try_create_for_raw_bytes(ReadonlyBytes bytes, Optional<ByteString> mime_type)
 {
     if (OwnPtr<ImageDecoderPlugin> plugin = probe_and_sniff_for_appropriate_plugin(bytes); plugin)
         return adopt_ref_if_nonnull(new (nothrow) ImageDecoder(plugin.release_nonnull()));
diff --git a/Userland/Libraries/LibGfx/ImageFormats/ImageDecoder.h b/Userland/Libraries/LibGfx/ImageFormats/ImageDecoder.h
index 5362b3c4ed4..55d08e04caa 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/ImageDecoder.h
+++ b/Userland/Libraries/LibGfx/ImageFormats/ImageDecoder.h
@@ -62,7 +62,7 @@ protected:
 
 class ImageDecoder : public RefCounted<ImageDecoder> {
 public:
-    static RefPtr<ImageDecoder> try_create_for_raw_bytes(ReadonlyBytes, Optional<DeprecatedString> mime_type = {});
+    static RefPtr<ImageDecoder> try_create_for_raw_bytes(ReadonlyBytes, Optional<ByteString> mime_type = {});
     ~ImageDecoder() = default;
 
     IntSize size() const { return m_plugin->size(); }
diff --git a/Userland/Libraries/LibGfx/Line.h b/Userland/Libraries/LibGfx/Line.h
index d660bde19b7..5089704df74 100644
--- a/Userland/Libraries/LibGfx/Line.h
+++ b/Userland/Libraries/LibGfx/Line.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/Optional.h>
 #include <LibGfx/Forward.h>
@@ -166,7 +166,7 @@ public:
         return Line<U>(*this);
     }
 
-    DeprecatedString to_deprecated_string() const;
+    ByteString to_byte_string() const;
 
 private:
     Point<T> m_a;
@@ -174,15 +174,15 @@ private:
 };
 
 template<>
-inline DeprecatedString IntLine::to_deprecated_string() const
+inline ByteString IntLine::to_byte_string() const
 {
-    return DeprecatedString::formatted("[{},{} -> {},{}]", m_a.x(), m_a.y(), m_b.x(), m_b.y());
+    return ByteString::formatted("[{},{} -> {},{}]", m_a.x(), m_a.y(), m_b.x(), m_b.y());
 }
 
 template<>
-inline DeprecatedString FloatLine::to_deprecated_string() const
+inline ByteString FloatLine::to_byte_string() const
 {
-    return DeprecatedString::formatted("[{},{} -> {},{}]", m_a.x(), m_a.y(), m_b.x(), m_b.y());
+    return ByteString::formatted("[{},{} -> {},{}]", m_a.x(), m_a.y(), m_b.x(), m_b.y());
 }
 
 }
diff --git a/Userland/Libraries/LibGfx/Painter.cpp b/Userland/Libraries/LibGfx/Painter.cpp
index df84adee8e5..4232a45680c 100644
--- a/Userland/Libraries/LibGfx/Painter.cpp
+++ b/Userland/Libraries/LibGfx/Painter.cpp
@@ -2384,10 +2384,10 @@ void Painter::blit_tiled(IntRect const& dst_rect, Gfx::Bitmap const& bitmap, Int
     }
 }
 
-DeprecatedString parse_ampersand_string(StringView raw_text, Optional<size_t>* underline_offset)
+ByteString parse_ampersand_string(StringView raw_text, Optional<size_t>* underline_offset)
 {
     if (raw_text.is_empty())
-        return DeprecatedString::empty();
+        return ByteString::empty();
 
     StringBuilder builder;
 
@@ -2403,7 +2403,7 @@ DeprecatedString parse_ampersand_string(StringView raw_text, Optional<size_t>* u
         }
         builder.append(raw_text[i]);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 void Gfx::Painter::draw_ui_text(Gfx::IntRect const& rect, StringView text, Gfx::Font const& font, Gfx::TextAlignment text_alignment, Gfx::Color color)
diff --git a/Userland/Libraries/LibGfx/Painter.h b/Userland/Libraries/LibGfx/Painter.h
index 8fd3621d29c..43b90ad19c4 100644
--- a/Userland/Libraries/LibGfx/Painter.h
+++ b/Userland/Libraries/LibGfx/Painter.h
@@ -232,6 +232,6 @@ private:
     Painter& m_painter;
 };
 
-DeprecatedString parse_ampersand_string(StringView, Optional<size_t>* underline_offset = nullptr);
+ByteString parse_ampersand_string(StringView, Optional<size_t>* underline_offset = nullptr);
 
 }
diff --git a/Userland/Libraries/LibGfx/Palette.cpp b/Userland/Libraries/LibGfx/Palette.cpp
index 4a1c28ca6fb..9ff2e109210 100644
--- a/Userland/Libraries/LibGfx/Palette.cpp
+++ b/Userland/Libraries/LibGfx/Palette.cpp
@@ -33,7 +33,7 @@ int PaletteImpl::metric(MetricRole role) const
     return theme().metric[(int)role];
 }
 
-DeprecatedString PaletteImpl::path(PathRole role) const
+ByteString PaletteImpl::path(PathRole role) const
 {
     VERIFY((int)role < (int)PathRole::__Count);
     return theme().path[(int)role];
@@ -78,7 +78,7 @@ void Palette::set_metric(MetricRole role, int value)
     theme.metric[(int)role] = value;
 }
 
-void Palette::set_path(PathRole role, DeprecatedString path)
+void Palette::set_path(PathRole role, ByteString path)
 {
     if (m_impl->ref_count() != 1)
         m_impl = m_impl->clone();
diff --git a/Userland/Libraries/LibGfx/Palette.h b/Userland/Libraries/LibGfx/Palette.h
index cffd4a31e5f..085c1755492 100644
--- a/Userland/Libraries/LibGfx/Palette.h
+++ b/Userland/Libraries/LibGfx/Palette.h
@@ -45,7 +45,7 @@ public:
     }
 
     int metric(MetricRole) const;
-    DeprecatedString path(PathRole) const;
+    ByteString path(PathRole) const;
     SystemTheme const& theme() const { return *m_theme_buffer.data<SystemTheme>(); }
 
     void replace_internal_buffer(Badge<GUI::Application>, Core::AnonymousBuffer buffer);
@@ -175,25 +175,25 @@ public:
     int window_title_button_width() const { return metric(MetricRole::TitleButtonWidth); }
     int window_title_button_height() const { return metric(MetricRole::TitleButtonHeight); }
 
-    DeprecatedString title_button_icons_path() const { return path(PathRole::TitleButtonIcons); }
-    DeprecatedString active_window_shadow_path() const { return path(PathRole::ActiveWindowShadow); }
-    DeprecatedString inactive_window_shadow_path() const { return path(PathRole::InactiveWindowShadow); }
-    DeprecatedString menu_shadow_path() const { return path(PathRole::MenuShadow); }
-    DeprecatedString taskbar_shadow_path() const { return path(PathRole::TaskbarShadow); }
-    DeprecatedString tooltip_shadow_path() const { return path(PathRole::TooltipShadow); }
-    DeprecatedString color_scheme_path() const { return path(PathRole::ColorScheme); }
+    ByteString title_button_icons_path() const { return path(PathRole::TitleButtonIcons); }
+    ByteString active_window_shadow_path() const { return path(PathRole::ActiveWindowShadow); }
+    ByteString inactive_window_shadow_path() const { return path(PathRole::InactiveWindowShadow); }
+    ByteString menu_shadow_path() const { return path(PathRole::MenuShadow); }
+    ByteString taskbar_shadow_path() const { return path(PathRole::TaskbarShadow); }
+    ByteString tooltip_shadow_path() const { return path(PathRole::TooltipShadow); }
+    ByteString color_scheme_path() const { return path(PathRole::ColorScheme); }
 
     Color color(ColorRole role) const { return m_impl->color(role); }
     Gfx::TextAlignment alignment(AlignmentRole role) const { return m_impl->alignment(role); }
     bool flag(FlagRole role) const { return m_impl->flag(role); }
     int metric(MetricRole role) const { return m_impl->metric(role); }
-    DeprecatedString path(PathRole role) const { return m_impl->path(role); }
+    ByteString path(PathRole role) const { return m_impl->path(role); }
 
     void set_color(ColorRole, Color);
     void set_alignment(AlignmentRole, Gfx::TextAlignment);
     void set_flag(FlagRole, bool);
     void set_metric(MetricRole, int);
-    void set_path(PathRole, DeprecatedString);
+    void set_path(PathRole, ByteString);
 
     SystemTheme const& theme() const { return m_impl->theme(); }
 
diff --git a/Userland/Libraries/LibGfx/Path.cpp b/Userland/Libraries/LibGfx/Path.cpp
index 2700dae0423..d57a8e96274 100644
--- a/Userland/Libraries/LibGfx/Path.cpp
+++ b/Userland/Libraries/LibGfx/Path.cpp
@@ -262,7 +262,7 @@ void Path::close_all_subpaths()
         close_previous_subpath();
 }
 
-DeprecatedString Path::to_deprecated_string() const
+ByteString Path::to_byte_string() const
 {
     StringBuilder builder;
     builder.append("Path { "sv);
@@ -289,13 +289,13 @@ DeprecatedString Path::to_deprecated_string() const
         switch (segment->type()) {
         case Segment::Type::QuadraticBezierCurveTo:
             builder.append(", "sv);
-            builder.append(static_cast<QuadraticBezierCurveSegment const&>(*segment).through().to_deprecated_string());
+            builder.append(static_cast<QuadraticBezierCurveSegment const&>(*segment).through().to_byte_string());
             break;
         case Segment::Type::CubicBezierCurveTo:
             builder.append(", "sv);
-            builder.append(static_cast<CubicBezierCurveSegment const&>(*segment).through_0().to_deprecated_string());
+            builder.append(static_cast<CubicBezierCurveSegment const&>(*segment).through_0().to_byte_string());
             builder.append(", "sv);
-            builder.append(static_cast<CubicBezierCurveSegment const&>(*segment).through_1().to_deprecated_string());
+            builder.append(static_cast<CubicBezierCurveSegment const&>(*segment).through_1().to_byte_string());
             break;
         default:
             break;
@@ -304,7 +304,7 @@ DeprecatedString Path::to_deprecated_string() const
         builder.append(") "sv);
     }
     builder.append('}');
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 void Path::segmentize_path()
diff --git a/Userland/Libraries/LibGfx/Path.h b/Userland/Libraries/LibGfx/Path.h
index 13ccf2f9338..f173a695900 100644
--- a/Userland/Libraries/LibGfx/Path.h
+++ b/Userland/Libraries/LibGfx/Path.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/Optional.h>
 #include <AK/Vector.h>
@@ -198,7 +198,7 @@ public:
     Path copy_transformed(AffineTransform const&) const;
     void add_path(Path const&);
     void ensure_subpath(FloatPoint point);
-    DeprecatedString to_deprecated_string() const;
+    ByteString to_byte_string() const;
 
     Path stroke_to_fill(float thickness) const;
 
diff --git a/Userland/Libraries/LibGfx/Point.cpp b/Userland/Libraries/LibGfx/Point.cpp
index eae4f9d1be5..c74af57d344 100644
--- a/Userland/Libraries/LibGfx/Point.cpp
+++ b/Userland/Libraries/LibGfx/Point.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibGfx/Point.h>
 #include <LibGfx/Rect.h>
 #include <LibIPC/Decoder.h>
@@ -36,15 +36,15 @@ template<typename T>
 }
 
 template<>
-DeprecatedString IntPoint::to_deprecated_string() const
+ByteString IntPoint::to_byte_string() const
 {
-    return DeprecatedString::formatted("[{},{}]", x(), y());
+    return ByteString::formatted("[{},{}]", x(), y());
 }
 
 template<>
-DeprecatedString FloatPoint::to_deprecated_string() const
+ByteString FloatPoint::to_byte_string() const
 {
-    return DeprecatedString::formatted("[{},{}]", x(), y());
+    return ByteString::formatted("[{},{}]", x(), y());
 }
 
 }
diff --git a/Userland/Libraries/LibGfx/Point.h b/Userland/Libraries/LibGfx/Point.h
index 77ba60328e8..bdf65b71449 100644
--- a/Userland/Libraries/LibGfx/Point.h
+++ b/Userland/Libraries/LibGfx/Point.h
@@ -261,7 +261,7 @@ public:
         return Point<U>(AK::floor(x()), AK::floor(y()));
     }
 
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
+    [[nodiscard]] ByteString to_byte_string() const;
 
 private:
     T m_x { 0 };
diff --git a/Userland/Libraries/LibGfx/Rect.cpp b/Userland/Libraries/LibGfx/Rect.cpp
index 99a475de5f0..69857dbb0c6 100644
--- a/Userland/Libraries/LibGfx/Rect.cpp
+++ b/Userland/Libraries/LibGfx/Rect.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <LibGfx/Line.h>
 #include <LibGfx/Rect.h>
@@ -14,15 +14,15 @@
 namespace Gfx {
 
 template<>
-DeprecatedString IntRect::to_deprecated_string() const
+ByteString IntRect::to_byte_string() const
 {
-    return DeprecatedString::formatted("[{},{} {}x{}]", x(), y(), width(), height());
+    return ByteString::formatted("[{},{} {}x{}]", x(), y(), width(), height());
 }
 
 template<>
-DeprecatedString FloatRect::to_deprecated_string() const
+ByteString FloatRect::to_byte_string() const
 {
-    return DeprecatedString::formatted("[{},{} {}x{}]", x(), y(), width(), height());
+    return ByteString::formatted("[{},{} {}x{}]", x(), y(), width(), height());
 }
 
 }
diff --git a/Userland/Libraries/LibGfx/Rect.h b/Userland/Libraries/LibGfx/Rect.h
index 0b3ad407a50..1efae132d31 100644
--- a/Userland/Libraries/LibGfx/Rect.h
+++ b/Userland/Libraries/LibGfx/Rect.h
@@ -1029,7 +1029,7 @@ public:
         };
     }
 
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
+    [[nodiscard]] ByteString to_byte_string() const;
 
 private:
     Point<T> m_location;
diff --git a/Userland/Libraries/LibGfx/Size.cpp b/Userland/Libraries/LibGfx/Size.cpp
index af997447d79..47b0dcd9cf1 100644
--- a/Userland/Libraries/LibGfx/Size.cpp
+++ b/Userland/Libraries/LibGfx/Size.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibGfx/Size.h>
 #include <LibIPC/Decoder.h>
 #include <LibIPC/Encoder.h>
@@ -12,15 +12,15 @@
 namespace Gfx {
 
 template<>
-DeprecatedString IntSize::to_deprecated_string() const
+ByteString IntSize::to_byte_string() const
 {
-    return DeprecatedString::formatted("[{}x{}]", m_width, m_height);
+    return ByteString::formatted("[{}x{}]", m_width, m_height);
 }
 
 template<>
-DeprecatedString FloatSize::to_deprecated_string() const
+ByteString FloatSize::to_byte_string() const
 {
-    return DeprecatedString::formatted("[{}x{}]", m_width, m_height);
+    return ByteString::formatted("[{}x{}]", m_width, m_height);
 }
 
 }
diff --git a/Userland/Libraries/LibGfx/Size.h b/Userland/Libraries/LibGfx/Size.h
index 4f247091066..26896d53aa1 100644
--- a/Userland/Libraries/LibGfx/Size.h
+++ b/Userland/Libraries/LibGfx/Size.h
@@ -181,7 +181,7 @@ public:
         return Size<U>(*this);
     }
 
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
+    [[nodiscard]] ByteString to_byte_string() const;
 
     template<Integral I>
     [[nodiscard]] Size<I> to_rounded() const
diff --git a/Userland/Libraries/LibGfx/SystemTheme.cpp b/Userland/Libraries/LibGfx/SystemTheme.cpp
index f67d50c99d3..1a9b41f813f 100644
--- a/Userland/Libraries/LibGfx/SystemTheme.cpp
+++ b/Userland/Libraries/LibGfx/SystemTheme.cpp
@@ -31,7 +31,7 @@ void set_system_theme(Core::AnonymousBuffer buffer)
     theme_page = theme_buffer.data<SystemTheme>();
 }
 
-ErrorOr<Core::AnonymousBuffer> load_system_theme(Core::ConfigFile const& file, Optional<DeprecatedString> const& color_scheme)
+ErrorOr<Core::AnonymousBuffer> load_system_theme(Core::ConfigFile const& file, Optional<ByteString> const& color_scheme)
 {
     auto buffer = TRY(Core::AnonymousBuffer::create_with_size(sizeof(SystemTheme)));
 
@@ -191,7 +191,7 @@ ErrorOr<Core::AnonymousBuffer> load_system_theme(Core::ConfigFile const& file, O
     return buffer;
 }
 
-ErrorOr<Core::AnonymousBuffer> load_system_theme(DeprecatedString const& path, Optional<DeprecatedString> const& color_scheme)
+ErrorOr<Core::AnonymousBuffer> load_system_theme(ByteString const& path, Optional<ByteString> const& color_scheme)
 {
     auto config_file = TRY(Core::ConfigFile::open(path));
     return TRY(load_system_theme(config_file, color_scheme));
@@ -203,7 +203,7 @@ ErrorOr<Vector<SystemThemeMetaData>> list_installed_system_themes()
     Core::DirIterator dt("/res/themes", Core::DirIterator::SkipDots);
     while (dt.has_next()) {
         auto theme_name = dt.next_path();
-        auto theme_path = DeprecatedString::formatted("/res/themes/{}", theme_name);
+        auto theme_path = ByteString::formatted("/res/themes/{}", theme_name);
         TRY(system_themes.try_append({ LexicalPath::title(theme_name), theme_path }));
     }
     quick_sort(system_themes, [](auto& a, auto& b) { return a.name < b.name; });
diff --git a/Userland/Libraries/LibGfx/SystemTheme.h b/Userland/Libraries/LibGfx/SystemTheme.h
index 9f274f1d26f..28ac08ec655 100644
--- a/Userland/Libraries/LibGfx/SystemTheme.h
+++ b/Userland/Libraries/LibGfx/SystemTheme.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/Types.h>
 #include <AK/Vector.h>
@@ -291,12 +291,12 @@ struct SystemTheme {
 
 Core::AnonymousBuffer& current_system_theme_buffer();
 void set_system_theme(Core::AnonymousBuffer);
-ErrorOr<Core::AnonymousBuffer> load_system_theme(Core::ConfigFile const&, Optional<DeprecatedString> const& color_scheme = OptionalNone());
-ErrorOr<Core::AnonymousBuffer> load_system_theme(DeprecatedString const& path, Optional<DeprecatedString> const& color_scheme = OptionalNone());
+ErrorOr<Core::AnonymousBuffer> load_system_theme(Core::ConfigFile const&, Optional<ByteString> const& color_scheme = OptionalNone());
+ErrorOr<Core::AnonymousBuffer> load_system_theme(ByteString const& path, Optional<ByteString> const& color_scheme = OptionalNone());
 
 struct SystemThemeMetaData {
-    DeprecatedString name;
-    DeprecatedString path;
+    ByteString name;
+    ByteString path;
 };
 
 ErrorOr<Vector<SystemThemeMetaData>> list_installed_system_themes();
diff --git a/Userland/Libraries/LibGfx/TextLayout.cpp b/Userland/Libraries/LibGfx/TextLayout.cpp
index 41e79f0878c..7941b29f815 100644
--- a/Userland/Libraries/LibGfx/TextLayout.cpp
+++ b/Userland/Libraries/LibGfx/TextLayout.cpp
@@ -44,7 +44,7 @@ FloatRect TextLayout::bounding_rect(TextWrapping wrapping) const
     return bounding_rect;
 }
 
-Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWrapping wrapping) const
+Vector<ByteString, 32> TextLayout::wrap_lines(TextElision elision, TextWrapping wrapping) const
 {
     Vector<Block> blocks;
 
@@ -110,14 +110,14 @@ Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWra
         });
     }
 
-    Vector<DeprecatedString> lines;
+    Vector<ByteString> lines;
     StringBuilder builder;
     float line_width = 0;
     size_t current_block = 0;
     for (Block& block : blocks) {
         switch (block.type) {
         case BlockType::Newline: {
-            lines.append(builder.to_deprecated_string());
+            lines.append(builder.to_byte_string());
             builder.clear();
             line_width = 0;
             current_block++;
@@ -133,7 +133,7 @@ Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWra
             }
 
             if (wrapping == TextWrapping::Wrap && line_width + block_width > m_rect.width()) {
-                lines.append(builder.to_deprecated_string());
+                lines.append(builder.to_byte_string());
                 builder.clear();
                 line_width = 0;
             }
@@ -145,7 +145,7 @@ Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWra
         }
     }
 
-    auto last_line = builder.to_deprecated_string();
+    auto last_line = builder.to_byte_string();
     if (!last_line.is_empty())
         lines.append(last_line);
 
@@ -161,7 +161,7 @@ Vector<DeprecatedString, 32> TextLayout::wrap_lines(TextElision elision, TextWra
     return lines;
 }
 
-DeprecatedString TextLayout::elide_text_from_right(Utf8View text) const
+ByteString TextLayout::elide_text_from_right(Utf8View text) const
 {
     float text_width = m_font.width(text);
     if (text_width > static_cast<float>(m_rect.width())) {
@@ -189,7 +189,7 @@ DeprecatedString TextLayout::elide_text_from_right(Utf8View text) const
             StringBuilder builder;
             builder.append(text.substring_view(0, offset).as_string());
             builder.append("..."sv);
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         }
     }
 
diff --git a/Userland/Libraries/LibGfx/TextLayout.h b/Userland/Libraries/LibGfx/TextLayout.h
index c627cf01f26..32dbd469211 100644
--- a/Userland/Libraries/LibGfx/TextLayout.h
+++ b/Userland/Libraries/LibGfx/TextLayout.h
@@ -7,8 +7,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Forward.h>
 #include <AK/Utf32View.h>
 #include <AK/Utf8View.h>
@@ -49,7 +49,7 @@ public:
     {
     }
 
-    Vector<DeprecatedString, 32> lines(TextElision elision, TextWrapping wrapping) const
+    Vector<ByteString, 32> lines(TextElision elision, TextWrapping wrapping) const
     {
         return wrap_lines(elision, wrapping);
     }
@@ -57,8 +57,8 @@ public:
     FloatRect bounding_rect(TextWrapping) const;
 
 private:
-    Vector<DeprecatedString, 32> wrap_lines(TextElision, TextWrapping) const;
-    DeprecatedString elide_text_from_right(Utf8View) const;
+    Vector<ByteString, 32> wrap_lines(TextElision, TextWrapping) const;
+    ByteString elide_text_from_right(Utf8View) const;
 
     Font const& m_font;
     FontPixelMetrics m_font_metrics;
diff --git a/Userland/Libraries/LibGfx/Triangle.cpp b/Userland/Libraries/LibGfx/Triangle.cpp
index e8e12ebfc08..d583109c01d 100644
--- a/Userland/Libraries/LibGfx/Triangle.cpp
+++ b/Userland/Libraries/LibGfx/Triangle.cpp
@@ -5,21 +5,21 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibGfx/Triangle.h>
 
 namespace Gfx {
 
 template<>
-DeprecatedString Triangle<int>::to_deprecated_string() const
+ByteString Triangle<int>::to_byte_string() const
 {
-    return DeprecatedString::formatted("({},{},{})", m_a, m_b, m_c);
+    return ByteString::formatted("({},{},{})", m_a, m_b, m_c);
 }
 
 template<>
-DeprecatedString Triangle<float>::to_deprecated_string() const
+ByteString Triangle<float>::to_byte_string() const
 {
-    return DeprecatedString::formatted("({},{},{})", m_a, m_b, m_c);
+    return ByteString::formatted("({},{},{})", m_a, m_b, m_c);
 }
 
 }
diff --git a/Userland/Libraries/LibGfx/Triangle.h b/Userland/Libraries/LibGfx/Triangle.h
index 11019c0d73f..4af7a61ea77 100644
--- a/Userland/Libraries/LibGfx/Triangle.h
+++ b/Userland/Libraries/LibGfx/Triangle.h
@@ -49,7 +49,7 @@ public:
         return true;
     }
 
-    DeprecatedString to_deprecated_string() const;
+    ByteString to_byte_string() const;
 
 private:
     T m_determinant { 0 };
diff --git a/Userland/Libraries/LibGfx/Vector2.h b/Userland/Libraries/LibGfx/Vector2.h
index 64efd3c7691..77400ffa605 100644
--- a/Userland/Libraries/LibGfx/Vector2.h
+++ b/Userland/Libraries/LibGfx/Vector2.h
@@ -29,7 +29,7 @@ template<typename T>
 struct Formatter<Gfx::Vector2<T>> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, Gfx::Vector2<T> const& value)
     {
-        return Formatter<StringView>::format(builder, value.to_deprecated_string());
+        return Formatter<StringView>::format(builder, value.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/Vector3.h b/Userland/Libraries/LibGfx/Vector3.h
index 7ff4ec40c8c..cd9d8deb453 100644
--- a/Userland/Libraries/LibGfx/Vector3.h
+++ b/Userland/Libraries/LibGfx/Vector3.h
@@ -29,7 +29,7 @@ template<typename T>
 struct Formatter<Gfx::Vector3<T>> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, Gfx::Vector3<T> const& value)
     {
-        return Formatter<StringView>::format(builder, value.to_deprecated_string());
+        return Formatter<StringView>::format(builder, value.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/Vector4.h b/Userland/Libraries/LibGfx/Vector4.h
index 829d7b2601d..23498ad4c33 100644
--- a/Userland/Libraries/LibGfx/Vector4.h
+++ b/Userland/Libraries/LibGfx/Vector4.h
@@ -29,7 +29,7 @@ template<typename T>
 struct Formatter<Gfx::Vector4<T>> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, Gfx::Vector4<T> const& value)
     {
-        return Formatter<StringView>::format(builder, value.to_deprecated_string());
+        return Formatter<StringView>::format(builder, value.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibGfx/VectorN.h b/Userland/Libraries/LibGfx/VectorN.h
index 9544fd91942..a2a5807c5c8 100644
--- a/Userland/Libraries/LibGfx/VectorN.h
+++ b/Userland/Libraries/LibGfx/VectorN.h
@@ -9,7 +9,7 @@
 #pragma once
 
 #include <AK/Array.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Math.h>
 #include <AK/StdLibExtras.h>
@@ -262,14 +262,14 @@ public:
         return VectorN<3, T>(x(), y(), z());
     }
 
-    [[nodiscard]] DeprecatedString to_deprecated_string() const
+    [[nodiscard]] ByteString to_byte_string() const
     {
         if constexpr (N == 2)
-            return DeprecatedString::formatted("[{},{}]", x(), y());
+            return ByteString::formatted("[{},{}]", x(), y());
         else if constexpr (N == 3)
-            return DeprecatedString::formatted("[{},{},{}]", x(), y(), z());
+            return ByteString::formatted("[{},{},{}]", x(), y(), z());
         else
-            return DeprecatedString::formatted("[{},{},{},{}]", x(), y(), z(), w());
+            return ByteString::formatted("[{},{},{},{}]", x(), y(), z(), w());
     }
 
     template<typename U>
diff --git a/Userland/Libraries/LibHTTP/HttpRequest.cpp b/Userland/Libraries/LibHTTP/HttpRequest.cpp
index d8196f549d7..dfca0967aa8 100644
--- a/Userland/Libraries/LibHTTP/HttpRequest.cpp
+++ b/Userland/Libraries/LibHTTP/HttpRequest.cpp
@@ -115,15 +115,15 @@ ErrorOr<HttpRequest, HttpRequest::ParseError> HttpRequest::from_raw_request(Read
     Vector<u8, 256> buffer;
 
     Optional<unsigned> content_length;
-    DeprecatedString method;
-    DeprecatedString resource;
-    DeprecatedString protocol;
+    ByteString method;
+    ByteString resource;
+    ByteString protocol;
     Vector<Header> headers;
     Header current_header;
     ByteBuffer body;
 
     auto commit_and_advance_to = [&](auto& output, State new_state) {
-        output = DeprecatedString::copy(buffer);
+        output = ByteString::copy(buffer);
         buffer.clear();
         state = new_state;
     };
@@ -237,8 +237,8 @@ ErrorOr<HttpRequest, HttpRequest::ParseError> HttpRequest::from_raw_request(Read
     request.m_headers = move(headers);
     auto url_parts = resource.split_limit('?', 2, SplitBehavior::KeepEmpty);
 
-    auto url_part_to_string = [](DeprecatedString const& url_part) -> ErrorOr<String, ParseError> {
-        auto query_string_or_error = String::from_deprecated_string(url_part);
+    auto url_part_to_string = [](ByteString const& url_part) -> ErrorOr<String, ParseError> {
+        auto query_string_or_error = String::from_byte_string(url_part);
         if (!query_string_or_error.is_error())
             return query_string_or_error.release_value();
 
@@ -263,7 +263,7 @@ ErrorOr<HttpRequest, HttpRequest::ParseError> HttpRequest::from_raw_request(Read
     return request;
 }
 
-void HttpRequest::set_headers(HashMap<DeprecatedString, DeprecatedString> const& headers)
+void HttpRequest::set_headers(HashMap<ByteString, ByteString> const& headers)
 {
     for (auto& it : headers)
         m_headers.append({ it.key, it.value });
@@ -283,10 +283,10 @@ Optional<HttpRequest::Header> HttpRequest::get_http_basic_authentication_header(
     builder.clear();
     builder.append("Basic "sv);
     builder.append(token);
-    return Header { "Authorization", builder.to_deprecated_string() };
+    return Header { "Authorization", builder.to_byte_string() };
 }
 
-Optional<HttpRequest::BasicAuthenticationCredentials> HttpRequest::parse_http_basic_authentication_header(DeprecatedString const& value)
+Optional<HttpRequest::BasicAuthenticationCredentials> HttpRequest::parse_http_basic_authentication_header(ByteString const& value)
 {
     if (!value.starts_with("Basic "sv, AK::CaseSensitivity::CaseInsensitive))
         return {};
@@ -296,7 +296,7 @@ Optional<HttpRequest::BasicAuthenticationCredentials> HttpRequest::parse_http_ba
     auto decoded_token_bb = decode_base64(token);
     if (decoded_token_bb.is_error())
         return {};
-    auto decoded_token = DeprecatedString::copy(decoded_token_bb.value());
+    auto decoded_token = ByteString::copy(decoded_token_bb.value());
     auto colon_index = decoded_token.find(':');
     if (!colon_index.has_value())
         return {};
diff --git a/Userland/Libraries/LibHTTP/HttpRequest.h b/Userland/Libraries/LibHTTP/HttpRequest.h
index e63326291a6..f41cbc2803c 100644
--- a/Userland/Libraries/LibHTTP/HttpRequest.h
+++ b/Userland/Libraries/LibHTTP/HttpRequest.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <AK/URL.h>
 #include <AK/Vector.h>
@@ -56,19 +56,19 @@ public:
     };
 
     struct Header {
-        DeprecatedString name;
-        DeprecatedString value;
+        ByteString name;
+        ByteString value;
     };
 
     struct BasicAuthenticationCredentials {
-        DeprecatedString username;
-        DeprecatedString password;
+        ByteString username;
+        ByteString password;
     };
 
     HttpRequest() = default;
     ~HttpRequest() = default;
 
-    DeprecatedString const& resource() const { return m_resource; }
+    ByteString const& resource() const { return m_resource; }
     Vector<Header> const& headers() const { return m_headers; }
 
     URL const& url() const { return m_url; }
@@ -83,15 +83,15 @@ public:
     StringView method_name() const;
     ErrorOr<ByteBuffer> to_raw_request() const;
 
-    void set_headers(HashMap<DeprecatedString, DeprecatedString> const&);
+    void set_headers(HashMap<ByteString, ByteString> const&);
 
     static ErrorOr<HttpRequest, HttpRequest::ParseError> from_raw_request(ReadonlyBytes);
     static Optional<Header> get_http_basic_authentication_header(URL const&);
-    static Optional<BasicAuthenticationCredentials> parse_http_basic_authentication_header(DeprecatedString const&);
+    static Optional<BasicAuthenticationCredentials> parse_http_basic_authentication_header(ByteString const&);
 
 private:
     URL m_url;
-    DeprecatedString m_resource;
+    ByteString m_resource;
     Method m_method { GET };
     Vector<Header> m_headers;
     ByteBuffer m_body;
diff --git a/Userland/Libraries/LibHTTP/HttpResponse.cpp b/Userland/Libraries/LibHTTP/HttpResponse.cpp
index bf68776e96e..f9f7af49756 100644
--- a/Userland/Libraries/LibHTTP/HttpResponse.cpp
+++ b/Userland/Libraries/LibHTTP/HttpResponse.cpp
@@ -9,7 +9,7 @@
 
 namespace HTTP {
 
-HttpResponse::HttpResponse(int code, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits>&& headers, size_t size)
+HttpResponse::HttpResponse(int code, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits>&& headers, size_t size)
     : m_code(code)
     , m_headers(move(headers))
     , m_downloaded_size(size)
diff --git a/Userland/Libraries/LibHTTP/HttpResponse.h b/Userland/Libraries/LibHTTP/HttpResponse.h
index 4010e9a9cc4..8215f103bf2 100644
--- a/Userland/Libraries/LibHTTP/HttpResponse.h
+++ b/Userland/Libraries/LibHTTP/HttpResponse.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <LibCore/NetworkResponse.h>
 
@@ -16,7 +16,7 @@ namespace HTTP {
 class HttpResponse : public Core::NetworkResponse {
 public:
     virtual ~HttpResponse() override = default;
-    static NonnullRefPtr<HttpResponse> create(int code, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits>&& headers, size_t downloaded_size)
+    static NonnullRefPtr<HttpResponse> create(int code, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits>&& headers, size_t downloaded_size)
     {
         return adopt_ref(*new HttpResponse(code, move(headers), downloaded_size));
     }
@@ -24,15 +24,15 @@ public:
     int code() const { return m_code; }
     size_t downloaded_size() const { return m_downloaded_size; }
     StringView reason_phrase() const { return reason_phrase_for_code(m_code); }
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& headers() const { return m_headers; }
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& headers() const { return m_headers; }
 
     static StringView reason_phrase_for_code(int code);
 
 private:
-    HttpResponse(int code, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits>&&, size_t size);
+    HttpResponse(int code, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits>&&, size_t size);
 
     int m_code { 0 };
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> m_headers;
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> m_headers;
     size_t m_downloaded_size { 0 };
 };
 
diff --git a/Userland/Libraries/LibHTTP/HttpsJob.cpp b/Userland/Libraries/LibHTTP/HttpsJob.cpp
index 76e3da828fd..28a2a5f6010 100644
--- a/Userland/Libraries/LibHTTP/HttpsJob.cpp
+++ b/Userland/Libraries/LibHTTP/HttpsJob.cpp
@@ -8,7 +8,7 @@
 
 namespace HTTP {
 
-void HttpsJob::set_certificate(DeprecatedString certificate, DeprecatedString key)
+void HttpsJob::set_certificate(ByteString certificate, ByteString key)
 {
     m_received_client_certificates = TLS::TLSv12::parse_pem_certificate(certificate.bytes(), key.bytes());
 }
diff --git a/Userland/Libraries/LibHTTP/HttpsJob.h b/Userland/Libraries/LibHTTP/HttpsJob.h
index 2b22c31b3cb..0be336e0988 100644
--- a/Userland/Libraries/LibHTTP/HttpsJob.h
+++ b/Userland/Libraries/LibHTTP/HttpsJob.h
@@ -25,7 +25,7 @@ public:
     bool received_client_certificates() const { return m_received_client_certificates.has_value(); }
     Vector<TLS::Certificate> take_client_certificates() const { return m_received_client_certificates.release_value(); }
 
-    void set_certificate(DeprecatedString certificate, DeprecatedString key);
+    void set_certificate(ByteString certificate, ByteString key);
 
     Function<Vector<TLS::Certificate>()> on_certificate_requested;
 
diff --git a/Userland/Libraries/LibHTTP/Job.cpp b/Userland/Libraries/LibHTTP/Job.cpp
index 9d7852cfb7d..aa68723556d 100644
--- a/Userland/Libraries/LibHTTP/Job.cpp
+++ b/Userland/Libraries/LibHTTP/Job.cpp
@@ -21,7 +21,7 @@
 
 namespace HTTP {
 
-static ErrorOr<ByteBuffer> handle_content_encoding(ByteBuffer const& buf, DeprecatedString const& content_encoding)
+static ErrorOr<ByteBuffer> handle_content_encoding(ByteBuffer const& buf, ByteString const& content_encoding)
 {
     dbgln_if(JOB_DEBUG, "Job::handle_content_encoding: buf has content_encoding={}", content_encoding);
 
@@ -173,11 +173,11 @@ void Job::register_on_ready_to_read(Function<void()> callback)
     };
 }
 
-ErrorOr<DeprecatedString> Job::read_line(size_t size)
+ErrorOr<ByteString> Job::read_line(size_t size)
 {
     auto buffer = TRY(ByteBuffer::create_uninitialized(size));
     auto bytes_read = TRY(m_socket->read_until(buffer, "\r\n"sv));
-    return DeprecatedString::copy(bytes_read);
+    return ByteString::copy(bytes_read);
 }
 
 ErrorOr<ByteBuffer> Job::receive(size_t size)
@@ -203,7 +203,7 @@ void Job::on_socket_connected()
 
     if constexpr (JOB_DEBUG) {
         dbgln("Job: raw_request:");
-        dbgln("{}", DeprecatedString::copy(raw_request));
+        dbgln("{}", ByteString::copy(raw_request));
     }
 
     bool success = !m_socket->write_until_depleted(raw_request).is_error();
@@ -304,7 +304,7 @@ void Job::on_socket_connected()
                 }
                 if (on_headers_received) {
                     if (!m_set_cookie_headers.is_empty())
-                        m_headers.set("Set-Cookie", JsonArray { m_set_cookie_headers }.to_deprecated_string());
+                        m_headers.set("Set-Cookie", JsonArray { m_set_cookie_headers }.to_byte_string());
                     on_headers_received(m_headers, m_code > 0 ? m_code : Optional<u32> {});
                 }
                 m_state = State::InBody;
@@ -361,7 +361,7 @@ void Job::on_socket_connected()
                 builder.append(existing_value.value());
                 builder.append(',');
                 builder.append(value);
-                m_headers.set(name, builder.to_deprecated_string());
+                m_headers.set(name, builder.to_byte_string());
             } else {
                 m_headers.set(name, value);
             }
@@ -423,7 +423,7 @@ void Job::on_socket_connected()
                         break;
                     } else {
                         auto chunk = size_lines[0].split_view(';', SplitBehavior::KeepEmpty);
-                        DeprecatedString size_string = chunk[0];
+                        ByteString size_string = chunk[0];
                         char* endptr;
                         auto size = strtoul(size_string.characters(), &endptr, 16);
                         if (*endptr) {
diff --git a/Userland/Libraries/LibHTTP/Job.h b/Userland/Libraries/LibHTTP/Job.h
index 771f3cee4f2..9734776d348 100644
--- a/Userland/Libraries/LibHTTP/Job.h
+++ b/Userland/Libraries/LibHTTP/Job.h
@@ -36,7 +36,7 @@ protected:
     void on_socket_connected();
     void flush_received_buffers();
     void register_on_ready_to_read(Function<void()>);
-    ErrorOr<DeprecatedString> read_line(size_t);
+    ErrorOr<ByteString> read_line(size_t);
     ErrorOr<ByteBuffer> receive(size_t);
     void timer_event(Core::TimerEvent&) override;
 
@@ -53,8 +53,8 @@ protected:
     Core::BufferedSocketBase* m_socket { nullptr };
     bool m_legacy_connection { false };
     int m_code { -1 };
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> m_headers;
-    Vector<DeprecatedString> m_set_cookie_headers;
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> m_headers;
+    Vector<ByteString> m_set_cookie_headers;
 
     struct ReceivedBuffer {
         ReceivedBuffer(ByteBuffer d)
diff --git a/Userland/Libraries/LibIDL/IDLParser.cpp b/Userland/Libraries/LibIDL/IDLParser.cpp
index 1c01639193c..f4054510518 100644
--- a/Userland/Libraries/LibIDL/IDLParser.cpp
+++ b/Userland/Libraries/LibIDL/IDLParser.cpp
@@ -49,7 +49,7 @@
     exit(EXIT_FAILURE);
 }
 
-static DeprecatedString convert_enumeration_value_to_cpp_enum_member(DeprecatedString const& value, HashTable<DeprecatedString>& names_already_seen)
+static ByteString convert_enumeration_value_to_cpp_enum_member(ByteString const& value, HashTable<ByteString>& names_already_seen)
 {
     StringBuilder builder;
     GenericLexer lexer { value };
@@ -73,7 +73,7 @@ static DeprecatedString convert_enumeration_value_to_cpp_enum_member(DeprecatedS
         builder.append('_');
 
     names_already_seen.set(builder.string_view());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 namespace IDL {
@@ -81,7 +81,7 @@ namespace IDL {
 void Parser::assert_specific(char ch)
 {
     if (!lexer.consume_specific(ch))
-        report_parsing_error(DeprecatedString::formatted("expected '{}'", ch), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("expected '{}'", ch), filename, input, lexer.tell());
 }
 
 void Parser::consume_whitespace()
@@ -101,12 +101,12 @@ void Parser::consume_whitespace()
 void Parser::assert_string(StringView expected)
 {
     if (!lexer.consume_specific(expected))
-        report_parsing_error(DeprecatedString::formatted("expected '{}'", expected), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("expected '{}'", expected), filename, input, lexer.tell());
 }
 
-HashMap<DeprecatedString, DeprecatedString> Parser::parse_extended_attributes()
+HashMap<ByteString, ByteString> Parser::parse_extended_attributes()
 {
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+    HashMap<ByteString, ByteString> extended_attributes;
     for (;;) {
         consume_whitespace();
         if (lexer.consume_specific(']'))
@@ -134,32 +134,32 @@ HashMap<DeprecatedString, DeprecatedString> Parser::parse_extended_attributes()
     return extended_attributes;
 }
 
-static HashTable<DeprecatedString> import_stack;
+static HashTable<ByteString> import_stack;
 Optional<Interface&> Parser::resolve_import(auto path)
 {
     auto include_path = LexicalPath::join(import_base_path, path).string();
     if (!FileSystem::exists(include_path))
-        report_parsing_error(DeprecatedString::formatted("{}: No such file or directory", include_path), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("{}: No such file or directory", include_path), filename, input, lexer.tell());
 
     auto real_path_error_or = FileSystem::real_path(include_path);
     if (real_path_error_or.is_error())
-        report_parsing_error(DeprecatedString::formatted("Failed to resolve path {}: {}", include_path, real_path_error_or.error()), filename, input, lexer.tell());
-    auto real_path = real_path_error_or.release_value().to_deprecated_string();
+        report_parsing_error(ByteString::formatted("Failed to resolve path {}: {}", include_path, real_path_error_or.error()), filename, input, lexer.tell());
+    auto real_path = real_path_error_or.release_value().to_byte_string();
 
     if (top_level_resolved_imports().contains(real_path))
         return *top_level_resolved_imports().find(real_path)->value;
 
     if (import_stack.contains(real_path))
-        report_parsing_error(DeprecatedString::formatted("Circular import detected: {}", include_path), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("Circular import detected: {}", include_path), filename, input, lexer.tell());
     import_stack.set(real_path);
 
     auto file_or_error = Core::File::open(real_path, Core::File::OpenMode::Read);
     if (file_or_error.is_error())
-        report_parsing_error(DeprecatedString::formatted("Failed to open {}: {}", real_path, file_or_error.error()), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("Failed to open {}: {}", real_path, file_or_error.error()), filename, input, lexer.tell());
 
     auto data_or_error = file_or_error.value()->read_until_eof();
     if (data_or_error.is_error())
-        report_parsing_error(DeprecatedString::formatted("Failed to read {}: {}", real_path, data_or_error.error()), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("Failed to read {}: {}", real_path, data_or_error.error()), filename, input, lexer.tell());
     auto& result = Parser(this, real_path, data_or_error.value(), import_base_path).parse();
     import_stack.remove(real_path);
 
@@ -255,12 +255,12 @@ NonnullRefPtr<Type const> Parser::parse_type()
     }
 
     if (is_parameterized_type)
-        return adopt_ref(*new ParameterizedType(builder.to_deprecated_string(), nullable, move(parameters)));
+        return adopt_ref(*new ParameterizedType(builder.to_byte_string(), nullable, move(parameters)));
 
-    return adopt_ref(*new Type(builder.to_deprecated_string(), nullable));
+    return adopt_ref(*new Type(builder.to_byte_string(), nullable));
 }
 
-void Parser::parse_attribute(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface& interface)
+void Parser::parse_attribute(HashMap<ByteString, ByteString>& extended_attributes, Interface& interface)
 {
     bool inherit = lexer.consume_specific("inherit");
     if (inherit)
@@ -282,9 +282,9 @@ void Parser::parse_attribute(HashMap<DeprecatedString, DeprecatedString>& extend
 
     assert_specific(';');
 
-    auto name_as_string = name.to_deprecated_string();
-    auto getter_callback_name = DeprecatedString::formatted("{}_getter", name_as_string.to_snakecase());
-    auto setter_callback_name = DeprecatedString::formatted("{}_setter", name_as_string.to_snakecase());
+    auto name_as_string = name.to_byte_string();
+    auto getter_callback_name = ByteString::formatted("{}_getter", name_as_string.to_snakecase());
+    auto setter_callback_name = ByteString::formatted("{}_setter", name_as_string.to_snakecase());
 
     Attribute attribute {
         inherit,
@@ -328,7 +328,7 @@ Vector<Parameter> Parser::parse_parameters()
     for (;;) {
         if (lexer.next_is(')'))
             break;
-        HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+        HashMap<ByteString, ByteString> extended_attributes;
         if (lexer.consume_specific('['))
             extended_attributes = parse_extended_attributes();
         bool optional = lexer.consume_specific("optional");
@@ -370,7 +370,7 @@ Vector<Parameter> Parser::parse_parameters()
     return parameters;
 }
 
-Function Parser::parse_function(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface& interface, IsSpecialOperation is_special_operation)
+Function Parser::parse_function(HashMap<ByteString, ByteString>& extended_attributes, Interface& interface, IsSpecialOperation is_special_operation)
 {
     bool static_ = false;
     if (lexer.consume_specific("static")) {
@@ -401,7 +401,7 @@ Function Parser::parse_function(HashMap<DeprecatedString, DeprecatedString>& ext
     return function;
 }
 
-void Parser::parse_constructor(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface& interface)
+void Parser::parse_constructor(HashMap<ByteString, ByteString>& extended_attributes, Interface& interface)
 {
     assert_string("constructor"sv);
     consume_whitespace();
@@ -414,7 +414,7 @@ void Parser::parse_constructor(HashMap<DeprecatedString, DeprecatedString>& exte
     interface.constructors.append(Constructor { interface.name, move(parameters), move(extended_attributes) });
 }
 
-void Parser::parse_stringifier(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface& interface)
+void Parser::parse_stringifier(HashMap<ByteString, ByteString>& extended_attributes, Interface& interface)
 {
     assert_string("stringifier"sv);
     consume_whitespace();
@@ -450,14 +450,14 @@ void Parser::parse_iterable(Interface& interface)
     assert_specific(';');
 }
 
-void Parser::parse_getter(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface& interface)
+void Parser::parse_getter(HashMap<ByteString, ByteString>& extended_attributes, Interface& interface)
 {
     assert_string("getter"sv);
     consume_whitespace();
     auto function = parse_function(extended_attributes, interface, IsSpecialOperation::Yes);
 
     if (function.parameters.size() != 1)
-        report_parsing_error(DeprecatedString::formatted("Named/indexed property getters must have only 1 parameter, got {} parameters.", function.parameters.size()), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("Named/indexed property getters must have only 1 parameter, got {} parameters.", function.parameters.size()), filename, input, lexer.tell());
 
     auto& identifier = function.parameters.first();
 
@@ -480,18 +480,18 @@ void Parser::parse_getter(HashMap<DeprecatedString, DeprecatedString>& extended_
 
         interface.indexed_property_getter = move(function);
     } else {
-        report_parsing_error(DeprecatedString::formatted("Named/indexed property getter's identifier's type must be either 'DOMString' or 'unsigned long', got '{}'.", identifier.type->name()), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("Named/indexed property getter's identifier's type must be either 'DOMString' or 'unsigned long', got '{}'.", identifier.type->name()), filename, input, lexer.tell());
     }
 }
 
-void Parser::parse_setter(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface& interface)
+void Parser::parse_setter(HashMap<ByteString, ByteString>& extended_attributes, Interface& interface)
 {
     assert_string("setter"sv);
     consume_whitespace();
     auto function = parse_function(extended_attributes, interface, IsSpecialOperation::Yes);
 
     if (function.parameters.size() != 2)
-        report_parsing_error(DeprecatedString::formatted("Named/indexed property setters must have only 2 parameters, got {} parameter(s).", function.parameters.size()), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("Named/indexed property setters must have only 2 parameters, got {} parameter(s).", function.parameters.size()), filename, input, lexer.tell());
 
     auto& identifier = function.parameters.first();
 
@@ -520,18 +520,18 @@ void Parser::parse_setter(HashMap<DeprecatedString, DeprecatedString>& extended_
 
         interface.indexed_property_setter = move(function);
     } else {
-        report_parsing_error(DeprecatedString::formatted("Named/indexed property setter's identifier's type must be either 'DOMString' or 'unsigned long', got '{}'.", identifier.type->name()), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("Named/indexed property setter's identifier's type must be either 'DOMString' or 'unsigned long', got '{}'.", identifier.type->name()), filename, input, lexer.tell());
     }
 }
 
-void Parser::parse_deleter(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface& interface)
+void Parser::parse_deleter(HashMap<ByteString, ByteString>& extended_attributes, Interface& interface)
 {
     assert_string("deleter"sv);
     consume_whitespace();
     auto function = parse_function(extended_attributes, interface, IsSpecialOperation::Yes);
 
     if (function.parameters.size() != 1)
-        report_parsing_error(DeprecatedString::formatted("Named property deleter must have only 1 parameter, got {} parameters.", function.parameters.size()), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("Named property deleter must have only 1 parameter, got {} parameters.", function.parameters.size()), filename, input, lexer.tell());
 
     auto& identifier = function.parameters.first();
 
@@ -552,7 +552,7 @@ void Parser::parse_deleter(HashMap<DeprecatedString, DeprecatedString>& extended
 
         interface.named_property_deleter = move(function);
     } else {
-        report_parsing_error(DeprecatedString::formatted("Named property deleter's identifier's type must be 'DOMString', got '{}'.", identifier.type->name()), filename, input, lexer.tell());
+        report_parsing_error(ByteString::formatted("Named property deleter's identifier's type must be 'DOMString', got '{}'.", identifier.type->name()), filename, input, lexer.tell());
     }
 }
 
@@ -569,7 +569,7 @@ void Parser::parse_interface(Interface& interface)
     assert_specific('{');
 
     for (;;) {
-        HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+        HashMap<ByteString, ByteString> extended_attributes;
 
         consume_whitespace();
 
@@ -629,14 +629,14 @@ void Parser::parse_interface(Interface& interface)
     }
 
     if (auto legacy_namespace = interface.extended_attributes.get("LegacyNamespace"sv); legacy_namespace.has_value())
-        interface.namespaced_name = DeprecatedString::formatted("{}.{}", *legacy_namespace, interface.name);
+        interface.namespaced_name = ByteString::formatted("{}.{}", *legacy_namespace, interface.name);
     else
         interface.namespaced_name = interface.name;
 
-    interface.constructor_class = DeprecatedString::formatted("{}Constructor", interface.name);
-    interface.prototype_class = DeprecatedString::formatted("{}Prototype", interface.name);
-    interface.prototype_base_class = DeprecatedString::formatted("{}Prototype", interface.parent_name.is_empty() ? "Object" : interface.parent_name);
-    interface.global_mixin_class = DeprecatedString::formatted("{}GlobalMixin", interface.name);
+    interface.constructor_class = ByteString::formatted("{}Constructor", interface.name);
+    interface.prototype_class = ByteString::formatted("{}Prototype", interface.name);
+    interface.prototype_base_class = ByteString::formatted("{}Prototype", interface.parent_name.is_empty() ? "Object" : interface.parent_name);
+    interface.global_mixin_class = ByteString::formatted("{}GlobalMixin", interface.name);
     consume_whitespace();
 }
 
@@ -659,15 +659,15 @@ void Parser::parse_namespace(Interface& interface)
             break;
         }
 
-        HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+        HashMap<ByteString, ByteString> extended_attributes;
         parse_function(extended_attributes, interface);
     }
 
-    interface.namespace_class = DeprecatedString::formatted("{}Namespace", interface.name);
+    interface.namespace_class = ByteString::formatted("{}Namespace", interface.name);
     consume_whitespace();
 }
 
-void Parser::parse_enumeration(HashMap<DeprecatedString, DeprecatedString> extended_attributes, Interface& interface)
+void Parser::parse_enumeration(HashMap<ByteString, ByteString> extended_attributes, Interface& interface)
 {
     assert_string("enum"sv);
     consume_whitespace();
@@ -696,7 +696,7 @@ void Parser::parse_enumeration(HashMap<DeprecatedString, DeprecatedString> exten
         consume_whitespace();
 
         if (enumeration.values.contains(string))
-            report_parsing_error(DeprecatedString::formatted("Enumeration {} contains duplicate member '{}'", name, string), filename, input, lexer.tell());
+            report_parsing_error(ByteString::formatted("Enumeration {} contains duplicate member '{}'", name, string), filename, input, lexer.tell());
         else
             enumeration.values.set(string);
 
@@ -710,7 +710,7 @@ void Parser::parse_enumeration(HashMap<DeprecatedString, DeprecatedString> exten
     assert_specific('}');
     assert_specific(';');
 
-    HashTable<DeprecatedString> names_already_seen;
+    HashTable<ByteString> names_already_seen;
     for (auto& entry : enumeration.values)
         enumeration.translated_cpp_names.set(entry, convert_enumeration_value_to_cpp_enum_member(entry, names_already_seen));
 
@@ -723,7 +723,7 @@ void Parser::parse_typedef(Interface& interface)
     assert_string("typedef"sv);
     consume_whitespace();
 
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+    HashMap<ByteString, ByteString> extended_attributes;
     if (lexer.consume_specific('['))
         extended_attributes = parse_extended_attributes();
 
@@ -764,7 +764,7 @@ void Parser::parse_dictionary(Interface& interface)
         }
 
         bool required = false;
-        HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+        HashMap<ByteString, ByteString> extended_attributes;
 
         if (lexer.consume_specific("required")) {
             required = true;
@@ -796,7 +796,7 @@ void Parser::parse_dictionary(Interface& interface)
             move(type),
             name,
             move(extended_attributes),
-            Optional<DeprecatedString>(move(default_value)),
+            Optional<ByteString>(move(default_value)),
         };
         dictionary.members.append(move(member));
     }
@@ -831,7 +831,7 @@ void Parser::parse_interface_mixin(Interface& interface)
     interface.mixins.set(move(name), &mixin_interface);
 }
 
-void Parser::parse_callback_function(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface& interface)
+void Parser::parse_callback_function(HashMap<ByteString, ByteString>& extended_attributes, Interface& interface)
 {
     assert_string("callback"sv);
     consume_whitespace();
@@ -859,7 +859,7 @@ void Parser::parse_non_interface_entities(bool allow_interface, Interface& inter
     consume_whitespace();
 
     while (!lexer.is_eof()) {
-        HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+        HashMap<ByteString, ByteString> extended_attributes;
         if (lexer.consume_specific('['))
             extended_attributes = parse_extended_attributes();
         if (lexer.next_is("dictionary")) {
@@ -897,7 +897,7 @@ void Parser::parse_non_interface_entities(bool allow_interface, Interface& inter
 
 static void resolve_union_typedefs(Interface& interface, UnionType& union_);
 
-static void resolve_typedef(Interface& interface, NonnullRefPtr<Type const>& type, HashMap<DeprecatedString, DeprecatedString>* extended_attributes = {})
+static void resolve_typedef(Interface& interface, NonnullRefPtr<Type const>& type, HashMap<ByteString, ByteString>* extended_attributes = {})
 {
     if (is<ParameterizedType>(*type)) {
         auto& parameterized_type = const_cast<Type&>(*type).as_parameterized();
@@ -963,10 +963,10 @@ Interface& Parser::parse()
 {
     auto this_module_or_error = FileSystem::real_path(filename);
     if (this_module_or_error.is_error()) {
-        report_parsing_error(DeprecatedString::formatted("Failed to resolve path '{}': {}", filename, this_module_or_error.error()), filename, input, 0);
+        report_parsing_error(ByteString::formatted("Failed to resolve path '{}': {}", filename, this_module_or_error.error()), filename, input, 0);
         VERIFY_NOT_REACHED();
     }
-    auto this_module = this_module_or_error.release_value().to_deprecated_string();
+    auto this_module = this_module_or_error.release_value().to_byte_string();
 
     auto interface_ptr = make<Interface>();
     auto& interface = *interface_ptr;
@@ -976,7 +976,7 @@ Interface& Parser::parse()
 
     Vector<Interface&> imports;
     {
-        HashTable<DeprecatedString> required_imported_paths;
+        HashTable<ByteString> required_imported_paths;
         while (lexer.consume_specific("#import")) {
             consume_whitespace();
             assert_specific('<');
@@ -1018,7 +1018,7 @@ Interface& Parser::parse()
 
         for (auto& mixin : import.mixins) {
             if (auto it = interface.mixins.find(mixin.key); it != interface.mixins.end() && it->value != mixin.value)
-                report_parsing_error(DeprecatedString::formatted("Mixin '{}' was already defined in {}", mixin.key, mixin.value->module_own_path), filename, input, lexer.tell());
+                report_parsing_error(ByteString::formatted("Mixin '{}' was already defined in {}", mixin.key, mixin.value->module_own_path), filename, input, lexer.tell());
             interface.mixins.set(mixin.key, mixin.value);
         }
 
@@ -1031,7 +1031,7 @@ Interface& Parser::parse()
         for (auto& entry : it->value) {
             auto mixin_it = interface.mixins.find(entry);
             if (mixin_it == interface.mixins.end())
-                report_parsing_error(DeprecatedString::formatted("Mixin '{}' was never defined", entry), filename, input, lexer.tell());
+                report_parsing_error(ByteString::formatted("Mixin '{}' was never defined", entry), filename, input, lexer.tell());
 
             auto& mixin = mixin_it->value;
             interface.attributes.extend(mixin->attributes);
@@ -1039,7 +1039,7 @@ Interface& Parser::parse()
             interface.functions.extend(mixin->functions);
             interface.static_functions.extend(mixin->static_functions);
             if (interface.has_stringifier && mixin->has_stringifier)
-                report_parsing_error(DeprecatedString::formatted("Both interface '{}' and mixin '{}' have defined stringifier attributes", interface.name, mixin->name), filename, input, lexer.tell());
+                report_parsing_error(ByteString::formatted("Both interface '{}' and mixin '{}' have defined stringifier attributes", interface.name, mixin->name), filename, input, lexer.tell());
 
             if (mixin->has_stringifier) {
                 interface.stringifier_attribute = mixin->stringifier_attribute;
@@ -1122,7 +1122,7 @@ Interface& Parser::parse()
     return interface;
 }
 
-Parser::Parser(DeprecatedString filename, StringView contents, DeprecatedString import_base_path)
+Parser::Parser(ByteString filename, StringView contents, ByteString import_base_path)
     : import_base_path(move(import_base_path))
     , filename(move(filename))
     , input(contents)
@@ -1130,7 +1130,7 @@ Parser::Parser(DeprecatedString filename, StringView contents, DeprecatedString
 {
 }
 
-Parser::Parser(Parser* parent, DeprecatedString filename, StringView contents, DeprecatedString import_base_path)
+Parser::Parser(Parser* parent, ByteString filename, StringView contents, ByteString import_base_path)
     : import_base_path(move(import_base_path))
     , filename(move(filename))
     , input(contents)
@@ -1147,7 +1147,7 @@ Parser* Parser::top_level_parser()
     return current;
 }
 
-HashMap<DeprecatedString, Interface*>& Parser::top_level_resolved_imports()
+HashMap<ByteString, Interface*>& Parser::top_level_resolved_imports()
 {
     return top_level_parser()->resolved_imports;
 }
@@ -1157,7 +1157,7 @@ HashTable<NonnullOwnPtr<Interface>>& Parser::top_level_interfaces()
     return top_level_parser()->interfaces;
 }
 
-Vector<DeprecatedString> Parser::imported_files() const
+Vector<ByteString> Parser::imported_files() const
 {
     return const_cast<Parser*>(this)->top_level_resolved_imports().keys();
 }
diff --git a/Userland/Libraries/LibIDL/IDLParser.h b/Userland/Libraries/LibIDL/IDLParser.h
index 53b88f74882..0168da28618 100644
--- a/Userland/Libraries/LibIDL/IDLParser.h
+++ b/Userland/Libraries/LibIDL/IDLParser.h
@@ -17,10 +17,10 @@ namespace IDL {
 
 class Parser {
 public:
-    Parser(DeprecatedString filename, StringView contents, DeprecatedString import_base_path);
+    Parser(ByteString filename, StringView contents, ByteString import_base_path);
     Interface& parse();
 
-    Vector<DeprecatedString> imported_files() const;
+    Vector<ByteString> imported_files() const;
 
 private:
     // https://webidl.spec.whatwg.org/#dfn-special-operation
@@ -30,43 +30,43 @@ private:
         Yes,
     };
 
-    Parser(Parser* parent, DeprecatedString filename, StringView contents, DeprecatedString import_base_path);
+    Parser(Parser* parent, ByteString filename, StringView contents, ByteString import_base_path);
 
     void assert_specific(char ch);
     void assert_string(StringView expected);
     void consume_whitespace();
     Optional<Interface&> resolve_import(auto path);
 
-    HashMap<DeprecatedString, DeprecatedString> parse_extended_attributes();
-    void parse_attribute(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface&);
+    HashMap<ByteString, ByteString> parse_extended_attributes();
+    void parse_attribute(HashMap<ByteString, ByteString>& extended_attributes, Interface&);
     void parse_interface(Interface&);
     void parse_namespace(Interface&);
     void parse_non_interface_entities(bool allow_interface, Interface&);
-    void parse_enumeration(HashMap<DeprecatedString, DeprecatedString>, Interface&);
+    void parse_enumeration(HashMap<ByteString, ByteString>, Interface&);
     void parse_typedef(Interface&);
     void parse_interface_mixin(Interface&);
     void parse_dictionary(Interface&);
-    void parse_callback_function(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface&);
-    void parse_constructor(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface&);
-    void parse_getter(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface&);
-    void parse_setter(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface&);
-    void parse_deleter(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface&);
-    void parse_stringifier(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface&);
+    void parse_callback_function(HashMap<ByteString, ByteString>& extended_attributes, Interface&);
+    void parse_constructor(HashMap<ByteString, ByteString>& extended_attributes, Interface&);
+    void parse_getter(HashMap<ByteString, ByteString>& extended_attributes, Interface&);
+    void parse_setter(HashMap<ByteString, ByteString>& extended_attributes, Interface&);
+    void parse_deleter(HashMap<ByteString, ByteString>& extended_attributes, Interface&);
+    void parse_stringifier(HashMap<ByteString, ByteString>& extended_attributes, Interface&);
     void parse_iterable(Interface&);
-    Function parse_function(HashMap<DeprecatedString, DeprecatedString>& extended_attributes, Interface&, IsSpecialOperation is_special_operation = IsSpecialOperation::No);
+    Function parse_function(HashMap<ByteString, ByteString>& extended_attributes, Interface&, IsSpecialOperation is_special_operation = IsSpecialOperation::No);
     Vector<Parameter> parse_parameters();
     NonnullRefPtr<Type const> parse_type();
     void parse_constant(Interface&);
 
-    DeprecatedString import_base_path;
-    DeprecatedString filename;
+    ByteString import_base_path;
+    ByteString filename;
     StringView input;
     GenericLexer lexer;
 
     HashTable<NonnullOwnPtr<Interface>>& top_level_interfaces();
     HashTable<NonnullOwnPtr<Interface>> interfaces;
-    HashMap<DeprecatedString, Interface*>& top_level_resolved_imports();
-    HashMap<DeprecatedString, Interface*> resolved_imports;
+    HashMap<ByteString, Interface*>& top_level_resolved_imports();
+    HashMap<ByteString, Interface*> resolved_imports;
     Parser* top_level_parser();
     Parser* parent = nullptr;
 };
diff --git a/Userland/Libraries/LibIDL/Types.h b/Userland/Libraries/LibIDL/Types.h
index 0a2aae59313..d074b812c7b 100644
--- a/Userland/Libraries/LibIDL/Types.h
+++ b/Userland/Libraries/LibIDL/Types.h
@@ -10,7 +10,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/SourceGenerator.h>
@@ -37,7 +37,7 @@ enum class SequenceStorageType {
 };
 
 struct CppType {
-    DeprecatedString name;
+    ByteString name;
     SequenceStorageType sequence_storage_type;
 };
 
@@ -53,14 +53,14 @@ public:
         Union,
     };
 
-    Type(DeprecatedString name, bool nullable)
+    Type(ByteString name, bool nullable)
         : m_kind(Kind::Plain)
         , m_name(move(name))
         , m_nullable(nullable)
     {
     }
 
-    Type(Kind kind, DeprecatedString name, bool nullable)
+    Type(Kind kind, ByteString name, bool nullable)
         : m_kind(kind)
         , m_name(move(name))
         , m_nullable(nullable)
@@ -81,7 +81,7 @@ public:
     UnionType const& as_union() const;
     UnionType& as_union();
 
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
 
     bool is_nullable() const { return m_nullable; }
     void set_nullable(bool value) { m_nullable = value; }
@@ -140,24 +140,24 @@ public:
 
 private:
     Kind m_kind;
-    DeprecatedString m_name;
+    ByteString m_name;
     bool m_nullable { false };
 };
 
 struct Parameter {
     NonnullRefPtr<Type const> type;
-    DeprecatedString name;
+    ByteString name;
     bool optional { false };
-    Optional<DeprecatedString> optional_default_value;
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+    Optional<ByteString> optional_default_value;
+    HashMap<ByteString, ByteString> extended_attributes;
     bool variadic { false };
 };
 
 struct Function {
     NonnullRefPtr<Type const> return_type;
-    DeprecatedString name;
+    ByteString name;
     Vector<Parameter> parameters;
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+    HashMap<ByteString, ByteString> extended_attributes;
     size_t overload_index { 0 };
     bool is_overloaded { false };
 
@@ -165,54 +165,54 @@ struct Function {
 };
 
 struct Constructor {
-    DeprecatedString name;
+    ByteString name;
     Vector<Parameter> parameters;
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+    HashMap<ByteString, ByteString> extended_attributes;
 
     size_t shortest_length() const { return get_function_shortest_length(*this); }
 };
 
 struct Constant {
     NonnullRefPtr<Type const> type;
-    DeprecatedString name;
-    DeprecatedString value;
+    ByteString name;
+    ByteString value;
 };
 
 struct Attribute {
     bool inherit { false };
     bool readonly { false };
     NonnullRefPtr<Type const> type;
-    DeprecatedString name;
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+    ByteString name;
+    HashMap<ByteString, ByteString> extended_attributes;
 
     // Added for convenience after parsing
-    DeprecatedString getter_callback_name;
-    DeprecatedString setter_callback_name;
+    ByteString getter_callback_name;
+    ByteString setter_callback_name;
 };
 
 struct DictionaryMember {
     bool required { false };
     NonnullRefPtr<Type const> type;
-    DeprecatedString name;
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
-    Optional<DeprecatedString> default_value;
+    ByteString name;
+    HashMap<ByteString, ByteString> extended_attributes;
+    Optional<ByteString> default_value;
 };
 
 struct Dictionary {
-    DeprecatedString parent_name;
+    ByteString parent_name;
     Vector<DictionaryMember> members;
 };
 
 struct Typedef {
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+    HashMap<ByteString, ByteString> extended_attributes;
     NonnullRefPtr<Type const> type;
 };
 
 struct Enumeration {
-    OrderedHashTable<DeprecatedString> values;
-    OrderedHashMap<DeprecatedString, DeprecatedString> translated_cpp_names;
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
-    DeprecatedString first_member;
+    OrderedHashTable<ByteString> values;
+    OrderedHashMap<ByteString, ByteString> translated_cpp_names;
+    HashMap<ByteString, ByteString> extended_attributes;
+    ByteString first_member;
     bool is_original_definition { true };
 };
 
@@ -224,7 +224,7 @@ struct CallbackFunction {
 
 class ParameterizedType : public Type {
 public:
-    ParameterizedType(DeprecatedString name, bool nullable, Vector<NonnullRefPtr<Type const>> parameters)
+    ParameterizedType(ByteString name, bool nullable, Vector<NonnullRefPtr<Type const>> parameters)
         : Type(Kind::Parameterized, move(name), nullable)
         , m_parameters(move(parameters))
     {
@@ -232,7 +232,7 @@ public:
 
     virtual ~ParameterizedType() override = default;
 
-    void generate_sequence_from_iterable(SourceGenerator& generator, DeprecatedString const& cpp_name, DeprecatedString const& iterable_cpp_name, DeprecatedString const& iterator_method_cpp_name, IDL::Interface const&, size_t recursion_depth) const;
+    void generate_sequence_from_iterable(SourceGenerator& generator, ByteString const& cpp_name, ByteString const& iterable_cpp_name, ByteString const& iterator_method_cpp_name, IDL::Interface const&, size_t recursion_depth) const;
 
     Vector<NonnullRefPtr<Type const>> const& parameters() const { return m_parameters; }
     Vector<NonnullRefPtr<Type const>>& parameters() { return m_parameters; }
@@ -256,14 +256,14 @@ class Interface {
 public:
     explicit Interface() = default;
 
-    DeprecatedString name;
-    DeprecatedString parent_name;
-    DeprecatedString namespaced_name;
+    ByteString name;
+    ByteString parent_name;
+    ByteString namespaced_name;
 
     bool is_namespace { false };
     bool is_mixin { false };
 
-    HashMap<DeprecatedString, DeprecatedString> extended_attributes;
+    HashMap<ByteString, ByteString> extended_attributes;
 
     Vector<Attribute> attributes;
     Vector<Constant> constants;
@@ -271,7 +271,7 @@ public:
     Vector<Function> functions;
     Vector<Function> static_functions;
     bool has_stringifier { false };
-    Optional<DeprecatedString> stringifier_attribute;
+    Optional<ByteString> stringifier_attribute;
     bool has_unscopable_member { false };
 
     Optional<NonnullRefPtr<Type const>> value_iterator_type;
@@ -285,27 +285,27 @@ public:
 
     Optional<Function> named_property_deleter;
 
-    HashMap<DeprecatedString, Dictionary> dictionaries;
-    HashMap<DeprecatedString, Enumeration> enumerations;
-    HashMap<DeprecatedString, Typedef> typedefs;
-    HashMap<DeprecatedString, Interface*> mixins;
-    HashMap<DeprecatedString, CallbackFunction> callback_functions;
+    HashMap<ByteString, Dictionary> dictionaries;
+    HashMap<ByteString, Enumeration> enumerations;
+    HashMap<ByteString, Typedef> typedefs;
+    HashMap<ByteString, Interface*> mixins;
+    HashMap<ByteString, CallbackFunction> callback_functions;
 
     // Added for convenience after parsing
-    DeprecatedString fully_qualified_name;
-    DeprecatedString constructor_class;
-    DeprecatedString prototype_class;
-    DeprecatedString prototype_base_class;
-    DeprecatedString namespace_class;
-    DeprecatedString global_mixin_class;
-    HashMap<DeprecatedString, HashTable<DeprecatedString>> included_mixins;
+    ByteString fully_qualified_name;
+    ByteString constructor_class;
+    ByteString prototype_class;
+    ByteString prototype_base_class;
+    ByteString namespace_class;
+    ByteString global_mixin_class;
+    HashMap<ByteString, HashTable<ByteString>> included_mixins;
 
-    DeprecatedString module_own_path;
-    HashTable<DeprecatedString> required_imported_paths;
+    ByteString module_own_path;
+    HashTable<ByteString> required_imported_paths;
     Vector<Interface&> imported_modules;
 
-    HashMap<DeprecatedString, Vector<Function&>> overload_sets;
-    HashMap<DeprecatedString, Vector<Function&>> static_overload_sets;
+    HashMap<ByteString, Vector<Function&>> overload_sets;
+    HashMap<ByteString, Vector<Function&>> static_overload_sets;
 
     // https://webidl.spec.whatwg.org/#dfn-support-indexed-properties
     bool supports_indexed_properties() const { return indexed_property_getter.has_value(); }
@@ -324,7 +324,7 @@ public:
 
 class UnionType : public Type {
 public:
-    UnionType(DeprecatedString name, bool nullable, Vector<NonnullRefPtr<Type const>> member_types)
+    UnionType(ByteString name, bool nullable, Vector<NonnullRefPtr<Type const>> member_types)
         : Type(Kind::Union, move(name), nullable)
         , m_member_types(move(member_types))
     {
diff --git a/Userland/Libraries/LibIMAP/Client.cpp b/Userland/Libraries/LibIMAP/Client.cpp
index ad95e72bd25..70fbb3e6c3d 100644
--- a/Userland/Libraries/LibIMAP/Client.cpp
+++ b/Userland/Libraries/LibIMAP/Client.cpp
@@ -64,7 +64,7 @@ bool Client::verify_response_is_complete()
     auto slice_data = MUST(m_buffer.slice(m_buffer.size() - slice_size, slice_size));
     StringView slice = StringView(slice_data);
     for (auto status : statuses) {
-        DeprecatedString pattern = DeprecatedString::formatted("A{} {}", m_current_command, status);
+        ByteString pattern = ByteString::formatted("A{} {}", m_current_command, status);
         if (slice.contains(pattern)) {
             dbgln("IMAP server replied {}, sending to parser", pattern);
             return true;
@@ -207,16 +207,16 @@ NonnullRefPtr<Promise<SolidResponse>> Client::login(StringView username, StringV
 NonnullRefPtr<Promise<SolidResponse>> Client::list(StringView reference_name, StringView mailbox)
 {
     auto command = Command { CommandType::List, m_current_command,
-        { DeprecatedString::formatted("\"{}\"", reference_name),
-            DeprecatedString::formatted("\"{}\"", mailbox) } };
+        { ByteString::formatted("\"{}\"", reference_name),
+            ByteString::formatted("\"{}\"", mailbox) } };
     return cast_promise<SolidResponse>(send_command(move(command)));
 }
 
 NonnullRefPtr<Promise<SolidResponse>> Client::lsub(StringView reference_name, StringView mailbox)
 {
     auto command = Command { CommandType::ListSub, m_current_command,
-        { DeprecatedString::formatted("\"{}\"", reference_name),
-            DeprecatedString::formatted("\"{}\"", mailbox) } };
+        { ByteString::formatted("\"{}\"", reference_name),
+            ByteString::formatted("\"{}\"", mailbox) } };
     return cast_promise<SolidResponse>(send_command(move(command)));
 }
 
@@ -270,7 +270,7 @@ ErrorOr<void> Client::send_next_command()
 {
     auto command = m_command_queue.take_first();
     ByteBuffer buffer;
-    auto tag = AK::DeprecatedString::formatted("A{} ", m_current_command);
+    auto tag = AK::ByteString::formatted("A{} ", m_current_command);
     buffer += tag.to_byte_buffer();
     auto command_type = command_byte_buffer(command.type);
     buffer.append(command_type.data(), command_type.size());
@@ -303,7 +303,7 @@ NonnullRefPtr<Promise<SolidResponse>> Client::delete_mailbox(StringView name)
     return cast_promise<SolidResponse>(send_command(move(command)));
 }
 
-NonnullRefPtr<Promise<SolidResponse>> Client::store(StoreMethod method, Sequence sequence_set, bool silent, Vector<DeprecatedString> const& flags, bool uid)
+NonnullRefPtr<Promise<SolidResponse>> Client::store(StoreMethod method, Sequence sequence_set, bool silent, Vector<ByteString> const& flags, bool uid)
 {
     StringBuilder data_item_name;
     switch (method) {
@@ -326,12 +326,12 @@ NonnullRefPtr<Promise<SolidResponse>> Client::store(StoreMethod method, Sequence
     flags_builder.join(' ', flags);
     flags_builder.append(')');
 
-    auto command = Command { uid ? CommandType::UIDStore : CommandType::Store, m_current_command, { sequence_set.serialize(), data_item_name.to_deprecated_string(), flags_builder.to_deprecated_string() } };
+    auto command = Command { uid ? CommandType::UIDStore : CommandType::Store, m_current_command, { sequence_set.serialize(), data_item_name.to_byte_string(), flags_builder.to_byte_string() } };
     return cast_promise<SolidResponse>(send_command(move(command)));
 }
-NonnullRefPtr<Promise<SolidResponse>> Client::search(Optional<DeprecatedString> charset, Vector<SearchKey>&& keys, bool uid)
+NonnullRefPtr<Promise<SolidResponse>> Client::search(Optional<ByteString> charset, Vector<SearchKey>&& keys, bool uid)
 {
-    Vector<DeprecatedString> args;
+    Vector<ByteString> args;
     if (charset.has_value()) {
         args.append("CHARSET "sv);
         args.append(charset.value());
@@ -359,7 +359,7 @@ NonnullRefPtr<Promise<SolidResponse>> Client::finish_idle()
 
 NonnullRefPtr<Promise<SolidResponse>> Client::status(StringView mailbox, Vector<StatusItemType> const& types)
 {
-    Vector<DeprecatedString> args;
+    Vector<ByteString> args;
     for (auto type : types) {
         switch (type) {
         case StatusItemType::Recent:
@@ -383,24 +383,24 @@ NonnullRefPtr<Promise<SolidResponse>> Client::status(StringView mailbox, Vector<
     types_list.append('(');
     types_list.join(' ', args);
     types_list.append(')');
-    auto command = Command { CommandType::Status, m_current_command, { mailbox, types_list.to_deprecated_string() } };
+    auto command = Command { CommandType::Status, m_current_command, { mailbox, types_list.to_byte_string() } };
     return cast_promise<SolidResponse>(send_command(move(command)));
 }
 
-NonnullRefPtr<Promise<SolidResponse>> Client::append(StringView mailbox, Message&& message, Optional<Vector<DeprecatedString>> flags, Optional<Core::DateTime> date_time)
+NonnullRefPtr<Promise<SolidResponse>> Client::append(StringView mailbox, Message&& message, Optional<Vector<ByteString>> flags, Optional<Core::DateTime> date_time)
 {
-    Vector<DeprecatedString> args = { mailbox };
+    Vector<ByteString> args = { mailbox };
     if (flags.has_value()) {
         StringBuilder flags_sb;
         flags_sb.append('(');
         flags_sb.join(' ', flags.value());
         flags_sb.append(')');
-        args.append(flags_sb.to_deprecated_string());
+        args.append(flags_sb.to_byte_string());
     }
     if (date_time.has_value())
-        args.append(date_time.value().to_deprecated_string("\"%d-%b-%Y %H:%M:%S +0000\""sv));
+        args.append(date_time.value().to_byte_string("\"%d-%b-%Y %H:%M:%S +0000\""sv));
 
-    args.append(DeprecatedString::formatted("{{{}}}", message.data.length()));
+    args.append(ByteString::formatted("{{{}}}", message.data.length()));
 
     auto continue_req = send_command(Command { CommandType::Append, m_current_command, args });
 
diff --git a/Userland/Libraries/LibIMAP/Client.h b/Userland/Libraries/LibIMAP/Client.h
index 1fd1ab85dbf..a44ea04ad2f 100644
--- a/Userland/Libraries/LibIMAP/Client.h
+++ b/Userland/Libraries/LibIMAP/Client.h
@@ -38,9 +38,9 @@ public:
     NonnullRefPtr<Promise<SolidResponse>> lsub(StringView reference_name, StringView mailbox_name);
     NonnullRefPtr<Promise<SolidResponse>> select(StringView string);
     NonnullRefPtr<Promise<SolidResponse>> examine(StringView string);
-    NonnullRefPtr<Promise<SolidResponse>> search(Optional<DeprecatedString> charset, Vector<SearchKey>&& search_keys, bool uid);
+    NonnullRefPtr<Promise<SolidResponse>> search(Optional<ByteString> charset, Vector<SearchKey>&& search_keys, bool uid);
     NonnullRefPtr<Promise<SolidResponse>> fetch(FetchCommand request, bool uid);
-    NonnullRefPtr<Promise<SolidResponse>> store(StoreMethod, Sequence, bool silent, Vector<DeprecatedString> const& flags, bool uid);
+    NonnullRefPtr<Promise<SolidResponse>> store(StoreMethod, Sequence, bool silent, Vector<ByteString> const& flags, bool uid);
     NonnullRefPtr<Promise<SolidResponse>> copy(Sequence sequence_set, StringView name, bool uid);
     NonnullRefPtr<Promise<SolidResponse>> create_mailbox(StringView name);
     NonnullRefPtr<Promise<SolidResponse>> delete_mailbox(StringView name);
@@ -51,7 +51,7 @@ public:
     NonnullRefPtr<Promise<ContinueRequest>> idle();
     NonnullRefPtr<Promise<SolidResponse>> finish_idle();
     NonnullRefPtr<Promise<SolidResponse>> status(StringView mailbox, Vector<StatusItemType> const& types);
-    NonnullRefPtr<Promise<SolidResponse>> append(StringView mailbox, Message&& message, Optional<Vector<DeprecatedString>> flags = {}, Optional<Core::DateTime> date_time = {});
+    NonnullRefPtr<Promise<SolidResponse>> append(StringView mailbox, Message&& message, Optional<Vector<ByteString>> flags = {}, Optional<Core::DateTime> date_time = {});
 
     bool is_open();
     void close();
diff --git a/Userland/Libraries/LibIMAP/MessageHeaderEncoding.cpp b/Userland/Libraries/LibIMAP/MessageHeaderEncoding.cpp
index 58ce45f6d3b..47151b1f977 100644
--- a/Userland/Libraries/LibIMAP/MessageHeaderEncoding.cpp
+++ b/Userland/Libraries/LibIMAP/MessageHeaderEncoding.cpp
@@ -20,7 +20,7 @@ ErrorOr<ByteBuffer> decode_rfc2047_encoded_words(StringView input)
 
     while (!lexer.is_eof()) {
         auto ascii_view = lexer.consume_until("=?"sv);
-        DeprecatedString ascii = ascii_view.replace("\r"sv, " "sv, ReplaceMode::All);
+        ByteString ascii = ascii_view.replace("\r"sv, " "sv, ReplaceMode::All);
         ascii = ascii.replace("\n"sv, " "sv, ReplaceMode::All);
         TRY(output.try_append(ascii));
         if (lexer.is_eof())
diff --git a/Userland/Libraries/LibIMAP/Objects.cpp b/Userland/Libraries/LibIMAP/Objects.cpp
index 1614d840c09..251b802c70e 100644
--- a/Userland/Libraries/LibIMAP/Objects.cpp
+++ b/Userland/Libraries/LibIMAP/Objects.cpp
@@ -9,18 +9,18 @@
 
 namespace IMAP {
 
-DeprecatedString Sequence::serialize() const
+ByteString Sequence::serialize() const
 {
     if (start == end) {
-        return AK::DeprecatedString::formatted("{}", start);
+        return AK::ByteString::formatted("{}", start);
     } else {
-        auto start_char = start != -1 ? DeprecatedString::formatted("{}", start) : "*";
-        auto end_char = end != -1 ? DeprecatedString::formatted("{}", end) : "*";
-        return DeprecatedString::formatted("{}:{}", start_char, end_char);
+        auto start_char = start != -1 ? ByteString::formatted("{}", start) : "*";
+        auto end_char = end != -1 ? ByteString::formatted("{}", end) : "*";
+        return ByteString::formatted("{}:{}", start_char, end_char);
     }
 }
 
-DeprecatedString FetchCommand::DataItem::Section::serialize() const
+ByteString FetchCommand::DataItem::Section::serialize() const
 {
     StringBuilder headers_builder;
     switch (type) {
@@ -41,7 +41,7 @@ DeprecatedString FetchCommand::DataItem::Section::serialize() const
             first = false;
         }
         headers_builder.append(')');
-        return headers_builder.to_deprecated_string();
+        return headers_builder.to_byte_string();
     }
     case SectionType::Text:
         return "TEXT";
@@ -57,12 +57,12 @@ DeprecatedString FetchCommand::DataItem::Section::serialize() const
         if (ends_with_mime) {
             sb.append(".MIME"sv);
         }
-        return sb.to_deprecated_string();
+        return sb.to_byte_string();
     }
     }
     VERIFY_NOT_REACHED();
 }
-DeprecatedString FetchCommand::DataItem::serialize() const
+ByteString FetchCommand::DataItem::serialize() const
 {
     switch (type) {
     case DataItemType::Envelope:
@@ -84,14 +84,14 @@ DeprecatedString FetchCommand::DataItem::serialize() const
             sb.appendff("<{}.{}>", start, octets);
         }
 
-        return sb.to_deprecated_string();
+        return sb.to_byte_string();
     }
     case DataItemType::BodyStructure:
         return "BODYSTRUCTURE";
     }
     VERIFY_NOT_REACHED();
 }
-DeprecatedString FetchCommand::serialize()
+ByteString FetchCommand::serialize()
 {
     StringBuilder sequence_builder;
     bool first = true;
@@ -113,9 +113,9 @@ DeprecatedString FetchCommand::serialize()
         first = false;
     }
 
-    return AK::DeprecatedString::formatted("{} ({})", sequence_builder.to_deprecated_string(), data_items_builder.to_deprecated_string());
+    return AK::ByteString::formatted("{} ({})", sequence_builder.to_byte_string(), data_items_builder.to_byte_string());
 }
-DeprecatedString serialize_astring(StringView string)
+ByteString serialize_astring(StringView string)
 {
     // Try to send an atom
     auto is_non_atom_char = [](char x) {
@@ -131,31 +131,31 @@ DeprecatedString serialize_astring(StringView string)
     auto can_be_quoted = !(string.contains('\n') || string.contains('\r'));
     if (can_be_quoted) {
         auto escaped_str = string.replace("\\"sv, "\\\\"sv, ReplaceMode::All).replace("\""sv, "\\\""sv, ReplaceMode::All);
-        return DeprecatedString::formatted("\"{}\"", escaped_str);
+        return ByteString::formatted("\"{}\"", escaped_str);
     }
 
     // Just send a literal
-    return DeprecatedString::formatted("{{{}}}\r\n{}", string.length(), string);
+    return ByteString::formatted("{{{}}}\r\n{}", string.length(), string);
 }
-DeprecatedString SearchKey::serialize() const
+ByteString SearchKey::serialize() const
 {
     return data.visit(
-        [&](All const&) { return DeprecatedString("ALL"); },
-        [&](Answered const&) { return DeprecatedString("ANSWERED"); },
-        [&](Bcc const& x) { return DeprecatedString::formatted("BCC {}", serialize_astring(x.bcc)); },
-        [&](Cc const& x) { return DeprecatedString::formatted("CC {}", serialize_astring(x.cc)); },
-        [&](Deleted const&) { return DeprecatedString("DELETED"); },
-        [&](Draft const&) { return DeprecatedString("DRAFT"); },
-        [&](From const& x) { return DeprecatedString::formatted("FROM {}", serialize_astring(x.from)); },
-        [&](Header const& x) { return DeprecatedString::formatted("HEADER {} {}", serialize_astring(x.header), serialize_astring(x.value)); },
-        [&](Keyword const& x) { return DeprecatedString::formatted("KEYWORD {}", x.keyword); },
-        [&](Larger const& x) { return DeprecatedString::formatted("LARGER {}", x.number); },
-        [&](New const&) { return DeprecatedString("NEW"); },
-        [&](Not const& x) { return DeprecatedString::formatted("NOT {}", x.operand->serialize()); },
-        [&](Old const&) { return DeprecatedString("OLD"); },
-        [&](On const& x) { return DeprecatedString::formatted("ON {}", x.date.to_deprecated_string("%d-%b-%Y"sv)); },
-        [&](Or const& x) { return DeprecatedString::formatted("OR {} {}", x.lhs->serialize(), x.rhs->serialize()); },
-        [&](Recent const&) { return DeprecatedString("RECENT"); },
+        [&](All const&) { return ByteString("ALL"); },
+        [&](Answered const&) { return ByteString("ANSWERED"); },
+        [&](Bcc const& x) { return ByteString::formatted("BCC {}", serialize_astring(x.bcc)); },
+        [&](Cc const& x) { return ByteString::formatted("CC {}", serialize_astring(x.cc)); },
+        [&](Deleted const&) { return ByteString("DELETED"); },
+        [&](Draft const&) { return ByteString("DRAFT"); },
+        [&](From const& x) { return ByteString::formatted("FROM {}", serialize_astring(x.from)); },
+        [&](Header const& x) { return ByteString::formatted("HEADER {} {}", serialize_astring(x.header), serialize_astring(x.value)); },
+        [&](Keyword const& x) { return ByteString::formatted("KEYWORD {}", x.keyword); },
+        [&](Larger const& x) { return ByteString::formatted("LARGER {}", x.number); },
+        [&](New const&) { return ByteString("NEW"); },
+        [&](Not const& x) { return ByteString::formatted("NOT {}", x.operand->serialize()); },
+        [&](Old const&) { return ByteString("OLD"); },
+        [&](On const& x) { return ByteString::formatted("ON {}", x.date.to_byte_string("%d-%b-%Y"sv)); },
+        [&](Or const& x) { return ByteString::formatted("OR {} {}", x.lhs->serialize(), x.rhs->serialize()); },
+        [&](Recent const&) { return ByteString("RECENT"); },
         [&](SearchKeys const& x) {
             StringBuilder sb;
             sb.append('(');
@@ -166,23 +166,23 @@ DeprecatedString SearchKey::serialize() const
                 sb.append(item->serialize());
                 first = false;
             }
-            return sb.to_deprecated_string();
+            return sb.to_byte_string();
         },
-        [&](Seen const&) { return DeprecatedString("SEEN"); },
-        [&](SentBefore const& x) { return DeprecatedString::formatted("SENTBEFORE {}", x.date.to_deprecated_string("%d-%b-%Y"sv)); },
-        [&](SentOn const& x) { return DeprecatedString::formatted("SENTON {}", x.date.to_deprecated_string("%d-%b-%Y"sv)); },
-        [&](SentSince const& x) { return DeprecatedString::formatted("SENTSINCE {}", x.date.to_deprecated_string("%d-%b-%Y"sv)); },
+        [&](Seen const&) { return ByteString("SEEN"); },
+        [&](SentBefore const& x) { return ByteString::formatted("SENTBEFORE {}", x.date.to_byte_string("%d-%b-%Y"sv)); },
+        [&](SentOn const& x) { return ByteString::formatted("SENTON {}", x.date.to_byte_string("%d-%b-%Y"sv)); },
+        [&](SentSince const& x) { return ByteString::formatted("SENTSINCE {}", x.date.to_byte_string("%d-%b-%Y"sv)); },
         [&](SequenceSet const& x) { return x.sequence.serialize(); },
-        [&](Since const& x) { return DeprecatedString::formatted("SINCE {}", x.date.to_deprecated_string("%d-%b-%Y"sv)); },
-        [&](Smaller const& x) { return DeprecatedString::formatted("SMALLER {}", x.number); },
-        [&](Subject const& x) { return DeprecatedString::formatted("SUBJECT {}", serialize_astring(x.subject)); },
-        [&](Text const& x) { return DeprecatedString::formatted("TEXT {}", serialize_astring(x.text)); },
-        [&](To const& x) { return DeprecatedString::formatted("TO {}", serialize_astring(x.to)); },
-        [&](UID const& x) { return DeprecatedString::formatted("UID {}", x.uid); },
-        [&](Unanswered const&) { return DeprecatedString("UNANSWERED"); },
-        [&](Undeleted const&) { return DeprecatedString("UNDELETED"); },
-        [&](Undraft const&) { return DeprecatedString("UNDRAFT"); },
-        [&](Unkeyword const& x) { return DeprecatedString::formatted("UNKEYWORD {}", serialize_astring(x.flag_keyword)); },
-        [&](Unseen const&) { return DeprecatedString("UNSEEN"); });
+        [&](Since const& x) { return ByteString::formatted("SINCE {}", x.date.to_byte_string("%d-%b-%Y"sv)); },
+        [&](Smaller const& x) { return ByteString::formatted("SMALLER {}", x.number); },
+        [&](Subject const& x) { return ByteString::formatted("SUBJECT {}", serialize_astring(x.subject)); },
+        [&](Text const& x) { return ByteString::formatted("TEXT {}", serialize_astring(x.text)); },
+        [&](To const& x) { return ByteString::formatted("TO {}", serialize_astring(x.to)); },
+        [&](UID const& x) { return ByteString::formatted("UID {}", x.uid); },
+        [&](Unanswered const&) { return ByteString("UNANSWERED"); },
+        [&](Undeleted const&) { return ByteString("UNDELETED"); },
+        [&](Undraft const&) { return ByteString("UNDRAFT"); },
+        [&](Unkeyword const& x) { return ByteString::formatted("UNKEYWORD {}", serialize_astring(x.flag_keyword)); },
+        [&](Unseen const&) { return ByteString("UNSEEN"); });
 }
 }
diff --git a/Userland/Libraries/LibIMAP/Objects.h b/Userland/Libraries/LibIMAP/Objects.h
index 6e6595cf7a0..0bd186e107e 100644
--- a/Userland/Libraries/LibIMAP/Objects.h
+++ b/Userland/Libraries/LibIMAP/Objects.h
@@ -115,8 +115,8 @@ public:
         m_status_items |= static_cast<unsigned>(type);
     }
 
-    void set_mailbox(DeprecatedString&& mailbox) { m_mailbox = move(mailbox); }
-    DeprecatedString& mailbox() { return m_mailbox; }
+    void set_mailbox(ByteString&& mailbox) { m_mailbox = move(mailbox); }
+    ByteString& mailbox() { return m_mailbox; }
 
     unsigned get(StatusItemType type) const
     {
@@ -165,60 +165,60 @@ private:
     unsigned m_uid_next { 0 };
     unsigned m_uid_validity { 0 };
     unsigned m_unseen { 0 };
-    DeprecatedString m_mailbox;
+    ByteString m_mailbox;
 };
 
 struct Address {
-    DeprecatedString name;
-    DeprecatedString source_route;
-    DeprecatedString mailbox;
-    DeprecatedString host;
+    ByteString name;
+    ByteString source_route;
+    ByteString mailbox;
+    ByteString host;
 };
 
 struct Envelope {
-    DeprecatedString date; // Format of date not specified.
-    DeprecatedString subject;
+    ByteString date; // Format of date not specified.
+    ByteString subject;
     Vector<Address> from;
     Vector<Address> sender;
     Vector<Address> reply_to;
     Vector<Address> to;
     Vector<Address> cc;
     Vector<Address> bcc;
-    DeprecatedString in_reply_to;
-    DeprecatedString message_id;
+    ByteString in_reply_to;
+    ByteString message_id;
 };
 
 class BodyStructure;
 
 struct BodyExtension {
-    AK::Variant<Optional<DeprecatedString>, unsigned, Vector<OwnPtr<BodyExtension>>> data;
+    AK::Variant<Optional<ByteString>, unsigned, Vector<OwnPtr<BodyExtension>>> data;
 };
 
 struct MultiPartBodyStructureData {
-    Optional<Tuple<DeprecatedString, HashMap<DeprecatedString, DeprecatedString>>> disposition;
+    Optional<Tuple<ByteString, HashMap<ByteString, ByteString>>> disposition;
     Vector<OwnPtr<BodyStructure>> bodies;
-    Vector<DeprecatedString> langs;
-    DeprecatedString multipart_subtype;
-    HashMap<DeprecatedString, DeprecatedString> params;
-    DeprecatedString location;
+    Vector<ByteString> langs;
+    ByteString multipart_subtype;
+    HashMap<ByteString, ByteString> params;
+    ByteString location;
     Vector<BodyExtension> extensions;
 };
 
 struct BodyStructureData {
-    DeprecatedString type;
-    DeprecatedString subtype;
-    DeprecatedString id {};
-    DeprecatedString desc {};
-    DeprecatedString encoding;
-    HashMap<DeprecatedString, DeprecatedString> fields;
+    ByteString type;
+    ByteString subtype;
+    ByteString id {};
+    ByteString desc {};
+    ByteString encoding;
+    HashMap<ByteString, ByteString> fields;
     unsigned bytes { 0 };
     unsigned lines { 0 };
     Optional<Tuple<Envelope, NonnullOwnPtr<BodyStructure>>> contanied_message;
 
-    DeprecatedString md5 {};
-    Optional<Tuple<DeprecatedString, HashMap<DeprecatedString, DeprecatedString>>> disposition {};
-    Optional<Vector<DeprecatedString>> langs {};
-    DeprecatedString location {};
+    ByteString md5 {};
+    Optional<Tuple<ByteString, HashMap<ByteString, ByteString>>> disposition {};
+    Optional<Vector<ByteString>> langs {};
+    ByteString location {};
 
     Vector<BodyExtension> extensions {};
 };
@@ -248,7 +248,7 @@ struct Sequence {
     int start;
     int end;
 
-    [[nodiscard]] DeprecatedString serialize() const;
+    [[nodiscard]] ByteString serialize() const;
 };
 
 struct FetchCommand {
@@ -276,9 +276,9 @@ struct FetchCommand {
             Optional<Vector<unsigned>> parts {};
             bool ends_with_mime {};
 
-            Optional<Vector<DeprecatedString>> headers {};
+            Optional<Vector<ByteString>> headers {};
 
-            [[nodiscard]] DeprecatedString serialize() const;
+            [[nodiscard]] ByteString serialize() const;
         };
 
         DataItemType type;
@@ -288,19 +288,19 @@ struct FetchCommand {
         int start { 0 };
         int octets { 0 };
 
-        [[nodiscard]] DeprecatedString serialize() const;
+        [[nodiscard]] ByteString serialize() const;
     };
 
     Vector<Sequence> sequence_set;
     Vector<DataItem> data_items;
 
-    DeprecatedString serialize();
+    ByteString serialize();
 };
 struct Command {
 public:
     CommandType type;
     int tag;
-    Vector<DeprecatedString> args;
+    Vector<ByteString> args;
 };
 
 enum class ResponseStatus {
@@ -311,8 +311,8 @@ enum class ResponseStatus {
 
 struct ListItem {
     unsigned flags;
-    DeprecatedString reference;
-    DeprecatedString name;
+    ByteString reference;
+    ByteString name;
 };
 
 class FetchResponseData {
@@ -332,13 +332,13 @@ public:
         m_response_type |= static_cast<unsigned>(type);
     }
 
-    void add_body_data(FetchCommand::DataItem&& data_item, DeprecatedString&& body)
+    void add_body_data(FetchCommand::DataItem&& data_item, ByteString&& body)
     {
         add_response_type(FetchResponseType::Body);
         m_bodies.append({ move(data_item), move(body) });
     }
 
-    Vector<Tuple<FetchCommand::DataItem, DeprecatedString>>& body_data()
+    Vector<Tuple<FetchCommand::DataItem, ByteString>>& body_data()
     {
         VERIFY(contains_response_type(FetchResponseType::Body));
         return m_bodies;
@@ -380,13 +380,13 @@ public:
         return m_envelope;
     }
 
-    void set_flags(Vector<DeprecatedString>&& flags)
+    void set_flags(Vector<ByteString>&& flags)
     {
         add_response_type(FetchResponseType::Flags);
         m_flags = move(flags);
     }
 
-    Vector<DeprecatedString>& flags()
+    Vector<ByteString>& flags()
     {
         VERIFY(contains_response_type(FetchResponseType::Flags));
         return m_flags;
@@ -410,8 +410,8 @@ public:
     }
 
 private:
-    Vector<DeprecatedString> m_flags;
-    Vector<Tuple<FetchCommand::DataItem, DeprecatedString>> m_bodies;
+    Vector<ByteString> m_flags;
+    Vector<Tuple<FetchCommand::DataItem, ByteString>> m_bodies;
     Core::DateTime m_internal_date;
     Envelope m_envelope;
     unsigned m_uid { 0 };
@@ -419,20 +419,20 @@ private:
     BodyStructure m_body_structure;
 };
 
-DeprecatedString serialize_astring(StringView string);
+ByteString serialize_astring(StringView string);
 
 struct SearchKey {
 public:
     // clang-format off
     struct All { };
     struct Answered { };
-    struct Bcc { DeprecatedString bcc; };
-    struct Cc { DeprecatedString cc; };
+    struct Bcc { ByteString bcc; };
+    struct Cc { ByteString cc; };
     struct Deleted { };
     struct Draft { };
-    struct From { DeprecatedString from; };
-    struct Header { DeprecatedString header; DeprecatedString value; };
-    struct Keyword { DeprecatedString keyword; };
+    struct From { ByteString from; };
+    struct Header { ByteString header; ByteString value; };
+    struct Keyword { ByteString keyword; };
     struct Larger { unsigned number; };
     struct New { };
     struct Not { OwnPtr<SearchKey> operand; };
@@ -448,14 +448,14 @@ public:
     struct SequenceSet { Sequence sequence; };
     struct Since { Core::DateTime date; };
     struct Smaller { unsigned number; };
-    struct Subject { DeprecatedString subject; };
-    struct Text { DeprecatedString text; };
-    struct To { DeprecatedString to; };
+    struct Subject { ByteString subject; };
+    struct Text { ByteString text; };
+    struct To { ByteString to; };
     struct UID { unsigned  uid; };
     struct Unanswered { };
     struct Undeleted { };
     struct Undraft { };
-    struct Unkeyword { DeprecatedString flag_keyword; };
+    struct Unkeyword { ByteString flag_keyword; };
     struct Unseen { };
     // clang-format on
 
@@ -487,7 +487,7 @@ public:
         return *this;
     }
 
-    [[nodiscard]] DeprecatedString serialize() const;
+    [[nodiscard]] ByteString serialize() const;
 };
 
 class ResponseData {
@@ -517,13 +517,13 @@ public:
         m_response_type = m_response_type | static_cast<unsigned>(response_type);
     }
 
-    void add_capabilities(Vector<DeprecatedString>&& capabilities)
+    void add_capabilities(Vector<ByteString>&& capabilities)
     {
         m_capabilities = move(capabilities);
         add_response_type(ResponseType::Capability);
     }
 
-    Vector<DeprecatedString>& capabilities()
+    Vector<ByteString>& capabilities()
     {
         VERIFY(contains_response_type(ResponseType::Capability));
         return m_capabilities;
@@ -613,25 +613,25 @@ public:
         return m_unseen;
     }
 
-    void set_flags(Vector<DeprecatedString>&& flags)
+    void set_flags(Vector<ByteString>&& flags)
     {
         m_response_type |= static_cast<unsigned>(ResponseType::Flags);
         m_flags = move(flags);
     }
 
-    Vector<DeprecatedString>& flags()
+    Vector<ByteString>& flags()
     {
         VERIFY(contains_response_type(ResponseType::Flags));
         return m_flags;
     }
 
-    void set_permanent_flags(Vector<DeprecatedString>&& flags)
+    void set_permanent_flags(Vector<ByteString>&& flags)
     {
         add_response_type(ResponseType::PermanentFlags);
         m_permanent_flags = move(flags);
     }
 
-    Vector<DeprecatedString>& permanent_flags()
+    Vector<ByteString>& permanent_flags()
     {
         VERIFY(contains_response_type(ResponseType::PermanentFlags));
         return m_permanent_flags;
@@ -673,13 +673,13 @@ public:
         return m_expunged;
     }
 
-    void set_bye(Optional<DeprecatedString> message)
+    void set_bye(Optional<ByteString> message)
     {
         add_response_type(ResponseType::Bye);
         m_bye_message = move(message);
     }
 
-    Optional<DeprecatedString>& bye_message()
+    Optional<ByteString>& bye_message()
     {
         VERIFY(contains_response_type(ResponseType::Bye));
         return m_bye_message;
@@ -699,7 +699,7 @@ public:
 private:
     unsigned m_response_type;
 
-    Vector<DeprecatedString> m_capabilities;
+    Vector<ByteString> m_capabilities;
     Vector<ListItem> m_list_items;
     Vector<ListItem> m_lsub_items;
     Vector<unsigned> m_expunged;
@@ -710,11 +710,11 @@ private:
     unsigned m_uid_next {};
     unsigned m_uid_validity {};
     unsigned m_unseen {};
-    Vector<DeprecatedString> m_permanent_flags;
-    Vector<DeprecatedString> m_flags;
+    Vector<ByteString> m_permanent_flags;
+    Vector<ByteString> m_flags;
     Vector<Tuple<unsigned, FetchResponseData>> m_fetch_responses;
     Vector<unsigned> m_search_results;
-    Optional<DeprecatedString> m_bye_message;
+    Optional<ByteString> m_bye_message;
     StatusItem m_status_item;
 };
 
@@ -735,7 +735,7 @@ public:
 
     ResponseData& data() { return m_data; }
 
-    DeprecatedString response_text() { return m_response_text; }
+    ByteString response_text() { return m_response_text; }
 
     SolidResponse()
         : SolidResponse(ResponseStatus::Bad, -1)
@@ -751,14 +751,14 @@ public:
 
 private:
     ResponseStatus m_status;
-    DeprecatedString m_response_text;
+    ByteString m_response_text;
     unsigned m_tag;
 
     ResponseData m_data;
 };
 
 struct ContinueRequest {
-    DeprecatedString data;
+    ByteString data;
 };
 
 using Response = Variant<SolidResponse, ContinueRequest>;
@@ -767,5 +767,5 @@ using Response = Variant<SolidResponse, ContinueRequest>;
 // An RFC 2822 message
 // https://datatracker.ietf.org/doc/html/rfc2822
 struct Message {
-    DeprecatedString data;
+    ByteString data;
 };
diff --git a/Userland/Libraries/LibIMAP/Parser.cpp b/Userland/Libraries/LibIMAP/Parser.cpp
index ca5a430eda8..beffd56bd61 100644
--- a/Userland/Libraries/LibIMAP/Parser.cpp
+++ b/Userland/Libraries/LibIMAP/Parser.cpp
@@ -94,7 +94,7 @@ ErrorOr<void> Parser::parse_response_done()
     }
 
     TRY(consume("\r\n"sv));
-    m_response.m_response_text = response_data.to_deprecated_string();
+    m_response.m_response_text = response_data.to_byte_string();
     return {};
 }
 
@@ -174,7 +174,7 @@ ErrorOr<void> Parser::parse_untagged()
         m_response.data().add_lsub_item(move(item));
     } else if (consume_if("FLAGS"sv)) {
         TRY(consume(" "sv));
-        auto flags = TRY(parse_list(+[](StringView x) { return DeprecatedString(x); }));
+        auto flags = TRY(parse_list(+[](StringView x) { return ByteString(x); }));
         m_response.data().set_flags(move(flags));
         TRY(consume("\r\n"sv));
     } else if (consume_if("OK"sv)) {
@@ -197,7 +197,7 @@ ErrorOr<void> Parser::parse_untagged()
                 m_response.data().set_unseen(n);
             } else if (actual_type == "PERMANENTFLAGS"sv) {
                 TRY(consume(" "sv));
-                auto flags = TRY(parse_list(+[](StringView x) { return DeprecatedString(x); }));
+                auto flags = TRY(parse_list(+[](StringView x) { return ByteString(x); }));
                 m_response.data().set_permanent_flags(move(flags));
             } else if (actual_type == "HIGHESTMODSEQ"sv) {
                 TRY(consume(" "sv));
@@ -222,7 +222,7 @@ ErrorOr<void> Parser::parse_untagged()
     } else if (consume_if("BYE"sv)) {
         auto message = consume_until_end_of_line();
         TRY(consume("\r\n"sv));
-        m_response.data().set_bye(message.is_empty() ? Optional<DeprecatedString>() : Optional<DeprecatedString>(message));
+        m_response.data().set_bye(message.is_empty() ? Optional<ByteString>() : Optional<ByteString>(message));
     } else if (consume_if("STATUS"sv)) {
         TRY(consume(" "sv));
         auto mailbox = TRY(parse_astring());
@@ -314,7 +314,7 @@ ErrorOr<FetchResponseData> Parser::parse_fetch_response()
         }
         case FetchCommand::DataItemType::Flags: {
             TRY(consume(" "sv));
-            auto flags = TRY(parse_list(+[](StringView x) { return DeprecatedString(x); }));
+            auto flags = TRY(parse_list(+[](StringView x) { return ByteString(x); }));
             fetch_response.set_flags(move(flags));
             break;
         }
@@ -398,7 +398,7 @@ ErrorOr<BodyStructure> Parser::parse_body_structure()
 
         if (!consume_if(")"sv)) {
             TRY(consume(" "sv));
-            data.params = consume_if("NIL"sv) ? HashMap<DeprecatedString, DeprecatedString> {} : TRY(parse_body_fields_params());
+            data.params = consume_if("NIL"sv) ? HashMap<ByteString, ByteString> {} : TRY(parse_body_fields_params());
             if (!consume_if(")"sv)) {
                 TRY(consume(" "sv));
                 if (!consume_if("NIL"sv)) {
@@ -413,7 +413,7 @@ ErrorOr<BodyStructure> Parser::parse_body_structure()
 
                     if (!consume_if(")"sv)) {
                         TRY(consume(" "sv));
-                        data.location = consume_if("NIL"sv) ? DeprecatedString {} : DeprecatedString(TRY(parse_string()));
+                        data.location = consume_if("NIL"sv) ? ByteString {} : ByteString(TRY(parse_string()));
 
                         if (!consume_if(")"sv)) {
                             TRY(consume(" "sv));
@@ -519,9 +519,9 @@ ErrorOr<BodyStructure> Parser::parse_one_part_body()
     return BodyStructure(move(data));
 }
 
-ErrorOr<Vector<DeprecatedString>> Parser::parse_langs()
+ErrorOr<Vector<ByteString>> Parser::parse_langs()
 {
-    AK::Vector<DeprecatedString> langs;
+    AK::Vector<ByteString> langs;
     if (!consume_if("("sv)) {
         langs.append(TRY(parse_string()));
     } else {
@@ -533,14 +533,14 @@ ErrorOr<Vector<DeprecatedString>> Parser::parse_langs()
     return langs;
 }
 
-ErrorOr<Tuple<DeprecatedString, HashMap<DeprecatedString, DeprecatedString>>> Parser::parse_disposition()
+ErrorOr<Tuple<ByteString, HashMap<ByteString, ByteString>>> Parser::parse_disposition()
 {
     TRY(consume("("sv));
     auto disposition_type = TRY(parse_string());
     TRY(consume(" "sv));
     auto disposition_vals = TRY(parse_body_fields_params());
     TRY(consume(")"sv));
-    return Tuple<DeprecatedString, HashMap<DeprecatedString, DeprecatedString>> { move(disposition_type), move(disposition_vals) };
+    return Tuple<ByteString, HashMap<ByteString, ByteString>> { move(disposition_type), move(disposition_vals) };
 }
 
 ErrorOr<StringView> Parser::parse_literal_string()
@@ -574,12 +574,12 @@ ErrorOr<ListItem> Parser::parse_list_item()
     TRY(consume("\" "sv));
     auto mailbox = TRY(parse_astring());
     TRY(consume("\r\n"sv));
-    return ListItem { flags, DeprecatedString(reference), DeprecatedString(mailbox) };
+    return ListItem { flags, ByteString(reference), ByteString(mailbox) };
 }
 
 ErrorOr<void> Parser::parse_capability_response()
 {
-    auto capability = AK::Vector<DeprecatedString>();
+    auto capability = AK::Vector<ByteString>();
     while (!consume_if("\r\n"sv)) {
         TRY(consume(" "sv));
         capability.append(TRY(parse_atom()));
@@ -709,7 +709,7 @@ ErrorOr<FetchCommand::DataItem> Parser::parse_fetch_data_item()
         auto section_type = consume_while([](u8 x) { return x != ']' && x != ' '; });
         if (section_type.equals_ignoring_ascii_case("HEADER.FIELDS"sv)) {
             data_item.section->type = FetchCommand::DataItem::SectionType::HeaderFields;
-            data_item.section->headers = Vector<DeprecatedString>();
+            data_item.section->headers = Vector<ByteString>();
             TRY(consume(" "sv));
             auto headers = TRY(parse_list(+[](StringView x) { return x; }));
             for (auto& header : headers) {
@@ -718,7 +718,7 @@ ErrorOr<FetchCommand::DataItem> Parser::parse_fetch_data_item()
             TRY(consume("]"sv));
         } else if (section_type.equals_ignoring_ascii_case("HEADER.FIELDS.NOT"sv)) {
             data_item.section->type = FetchCommand::DataItem::SectionType::HeaderFieldsNot;
-            data_item.section->headers = Vector<DeprecatedString>();
+            data_item.section->headers = Vector<ByteString>();
             TRY(consume(" ("sv));
             auto headers = TRY(parse_list(+[](StringView x) { return x; }));
             for (auto& header : headers) {
@@ -825,12 +825,12 @@ ErrorOr<StringView> Parser::parse_astring()
     return parse_atom();
 }
 
-ErrorOr<HashMap<DeprecatedString, DeprecatedString>> Parser::parse_body_fields_params()
+ErrorOr<HashMap<ByteString, ByteString>> Parser::parse_body_fields_params()
 {
     if (consume_if("NIL"sv))
-        return HashMap<DeprecatedString, DeprecatedString> {};
+        return HashMap<ByteString, ByteString> {};
 
-    HashMap<DeprecatedString, DeprecatedString> fields;
+    HashMap<ByteString, ByteString> fields;
     TRY(consume("("sv));
     while (!consume_if(")"sv)) {
         auto key = TRY(parse_string());
@@ -846,7 +846,7 @@ ErrorOr<HashMap<DeprecatedString, DeprecatedString>> Parser::parse_body_fields_p
 ErrorOr<BodyExtension> Parser::parse_body_extension()
 {
     if (consume_if("NIL"sv))
-        return BodyExtension { Optional<DeprecatedString> {} };
+        return BodyExtension { Optional<ByteString> {} };
 
     if (consume_if("("sv)) {
         Vector<OwnPtr<BodyExtension>> extensions;
diff --git a/Userland/Libraries/LibIMAP/Parser.h b/Userland/Libraries/LibIMAP/Parser.h
index a5c2386c30f..d3ea539c057 100644
--- a/Userland/Libraries/LibIMAP/Parser.h
+++ b/Userland/Libraries/LibIMAP/Parser.h
@@ -54,12 +54,12 @@ private:
     ErrorOr<FetchResponseData> parse_fetch_response();
     ErrorOr<Vector<Address>> parse_address_list();
     ErrorOr<Address> parse_address();
-    ErrorOr<HashMap<DeprecatedString, DeprecatedString>> parse_body_fields_params();
+    ErrorOr<HashMap<ByteString, ByteString>> parse_body_fields_params();
     ErrorOr<BodyStructure> parse_body_structure();
     ErrorOr<BodyStructure> parse_one_part_body();
     ErrorOr<BodyExtension> parse_body_extension();
-    ErrorOr<Tuple<DeprecatedString, HashMap<DeprecatedString, DeprecatedString>>> parse_disposition();
-    ErrorOr<Vector<DeprecatedString>> parse_langs();
+    ErrorOr<Tuple<ByteString, HashMap<ByteString, ByteString>>> parse_disposition();
+    ErrorOr<Vector<ByteString>> parse_langs();
     ErrorOr<Envelope> parse_envelope();
 
     template<typename T>
diff --git a/Userland/Libraries/LibIPC/Decoder.cpp b/Userland/Libraries/LibIPC/Decoder.cpp
index 69b418f96b3..9ef9dce5296 100644
--- a/Userland/Libraries/LibIPC/Decoder.cpp
+++ b/Userland/Libraries/LibIPC/Decoder.cpp
@@ -31,13 +31,13 @@ ErrorOr<String> decode(Decoder& decoder)
 }
 
 template<>
-ErrorOr<DeprecatedString> decode(Decoder& decoder)
+ErrorOr<ByteString> decode(Decoder& decoder)
 {
     auto length = TRY(decoder.decode_size());
     if (length == NumericLimits<u32>::max())
-        return DeprecatedString {};
+        return ByteString {};
     if (length == 0)
-        return DeprecatedString::empty();
+        return ByteString::empty();
 
     char* text_buffer = nullptr;
     auto text_impl = StringImpl::create_uninitialized(length, text_buffer);
@@ -45,7 +45,7 @@ ErrorOr<DeprecatedString> decode(Decoder& decoder)
     Bytes bytes { text_buffer, length };
     TRY(decoder.decode_into(bytes));
 
-    return DeprecatedString { *text_impl };
+    return ByteString { *text_impl };
 }
 
 template<>
@@ -65,7 +65,7 @@ ErrorOr<ByteBuffer> decode(Decoder& decoder)
 template<>
 ErrorOr<JsonValue> decode(Decoder& decoder)
 {
-    auto json = TRY(decoder.decode<DeprecatedString>());
+    auto json = TRY(decoder.decode<ByteString>());
     return JsonValue::from_string(json);
 }
 
@@ -86,7 +86,7 @@ ErrorOr<UnixDateTime> decode(Decoder& decoder)
 template<>
 ErrorOr<URL> decode(Decoder& decoder)
 {
-    auto url = TRY(decoder.decode<DeprecatedString>());
+    auto url = TRY(decoder.decode<ByteString>());
     return URL { url };
 }
 
diff --git a/Userland/Libraries/LibIPC/Decoder.h b/Userland/Libraries/LibIPC/Decoder.h
index e342082f8f3..a3338b456d7 100644
--- a/Userland/Libraries/LibIPC/Decoder.h
+++ b/Userland/Libraries/LibIPC/Decoder.h
@@ -7,8 +7,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/Concepts.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Forward.h>
 #include <AK/NumericLimits.h>
 #include <AK/StdLibExtras.h>
@@ -85,7 +85,7 @@ template<>
 ErrorOr<String> decode(Decoder&);
 
 template<>
-ErrorOr<DeprecatedString> decode(Decoder&);
+ErrorOr<ByteString> decode(Decoder&);
 
 template<>
 ErrorOr<ByteBuffer> decode(Decoder&);
diff --git a/Userland/Libraries/LibIPC/Encoder.cpp b/Userland/Libraries/LibIPC/Encoder.cpp
index 311c4cc67db..13de3bea0cb 100644
--- a/Userland/Libraries/LibIPC/Encoder.cpp
+++ b/Userland/Libraries/LibIPC/Encoder.cpp
@@ -8,7 +8,7 @@
 
 #include <AK/BitCast.h>
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonValue.h>
 #include <AK/NumericLimits.h>
@@ -65,7 +65,7 @@ ErrorOr<void> encode(Encoder& encoder, StringView const& value)
 }
 
 template<>
-ErrorOr<void> encode(Encoder& encoder, DeprecatedString const& value)
+ErrorOr<void> encode(Encoder& encoder, ByteString const& value)
 {
     return encoder.encode(value.view());
 }
@@ -99,7 +99,7 @@ ErrorOr<void> encode(Encoder& encoder, UnixDateTime const& value)
 template<>
 ErrorOr<void> encode(Encoder& encoder, URL const& value)
 {
-    return encoder.encode(value.to_deprecated_string());
+    return encoder.encode(value.to_byte_string());
 }
 
 template<>
diff --git a/Userland/Libraries/LibIPC/Encoder.h b/Userland/Libraries/LibIPC/Encoder.h
index 1588f124dd3..c1e5fc35ded 100644
--- a/Userland/Libraries/LibIPC/Encoder.h
+++ b/Userland/Libraries/LibIPC/Encoder.h
@@ -114,7 +114,7 @@ template<>
 ErrorOr<void> encode(Encoder&, StringView const&);
 
 template<>
-ErrorOr<void> encode(Encoder&, DeprecatedString const&);
+ErrorOr<void> encode(Encoder&, ByteString const&);
 
 template<>
 ErrorOr<void> encode(Encoder&, ByteBuffer const&);
diff --git a/Userland/Libraries/LibIPC/MultiServer.h b/Userland/Libraries/LibIPC/MultiServer.h
index 6efd056d11c..1417e31a104 100644
--- a/Userland/Libraries/LibIPC/MultiServer.h
+++ b/Userland/Libraries/LibIPC/MultiServer.h
@@ -16,7 +16,7 @@ namespace IPC {
 template<typename ConnectionFromClientType>
 class MultiServer {
 public:
-    static ErrorOr<NonnullOwnPtr<MultiServer>> try_create(Optional<DeprecatedString> socket_path = {})
+    static ErrorOr<NonnullOwnPtr<MultiServer>> try_create(Optional<ByteString> socket_path = {})
     {
         auto server = TRY(Core::LocalServer::try_create());
         TRY(server->take_over_from_system_server(socket_path.value_or({})));
diff --git a/Userland/Libraries/LibIPC/Stub.h b/Userland/Libraries/LibIPC/Stub.h
index b64afa824ce..7579f229f6e 100644
--- a/Userland/Libraries/LibIPC/Stub.h
+++ b/Userland/Libraries/LibIPC/Stub.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/OwnPtr.h>
 
 namespace AK {
@@ -24,14 +24,14 @@ public:
     virtual ~Stub() = default;
 
     virtual u32 magic() const = 0;
-    virtual DeprecatedString name() const = 0;
+    virtual ByteString name() const = 0;
     virtual ErrorOr<OwnPtr<MessageBuffer>> handle(Message const&) = 0;
 
 protected:
     Stub() = default;
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
 };
 
 }
diff --git a/Userland/Libraries/LibImageDecoderClient/Client.cpp b/Userland/Libraries/LibImageDecoderClient/Client.cpp
index 13e92195af0..ae085b8aa38 100644
--- a/Userland/Libraries/LibImageDecoderClient/Client.cpp
+++ b/Userland/Libraries/LibImageDecoderClient/Client.cpp
@@ -20,7 +20,7 @@ void Client::die()
         on_death();
 }
 
-Optional<DecodedImage> Client::decode_image(ReadonlyBytes encoded_data, Optional<DeprecatedString> mime_type)
+Optional<DecodedImage> Client::decode_image(ReadonlyBytes encoded_data, Optional<ByteString> mime_type)
 {
     if (encoded_data.is_empty())
         return {};
diff --git a/Userland/Libraries/LibImageDecoderClient/Client.h b/Userland/Libraries/LibImageDecoderClient/Client.h
index 835a5d61ffb..5862022cd2b 100644
--- a/Userland/Libraries/LibImageDecoderClient/Client.h
+++ b/Userland/Libraries/LibImageDecoderClient/Client.h
@@ -32,7 +32,7 @@ class Client final
 public:
     Client(NonnullOwnPtr<Core::LocalSocket>);
 
-    Optional<DecodedImage> decode_image(ReadonlyBytes, Optional<DeprecatedString> mime_type = {});
+    Optional<DecodedImage> decode_image(ReadonlyBytes, Optional<ByteString> mime_type = {});
 
     Function<void()> on_death;
 
diff --git a/Userland/Libraries/LibJS/AST.cpp b/Userland/Libraries/LibJS/AST.cpp
index d642400b99c..5d25a049588 100644
--- a/Userland/Libraries/LibJS/AST.cpp
+++ b/Userland/Libraries/LibJS/AST.cpp
@@ -51,7 +51,7 @@ SourceRange ASTNode::source_range() const
     return m_source_code->range_from_offsets(m_start_offset, m_end_offset);
 }
 
-DeprecatedString ASTNode::class_name() const
+ByteString ASTNode::class_name() const
 {
     // NOTE: We strip the "JS::" prefix.
     auto const* typename_ptr = typeid(*this).name();
@@ -60,7 +60,7 @@ DeprecatedString ASTNode::class_name() const
 
 static void print_indent(int indent)
 {
-    out("{}", DeprecatedString::repeated(' ', indent * 2));
+    out("{}", ByteString::repeated(' ', indent * 2));
 }
 
 static void update_function_name(Value value, DeprecatedFlyString const& name)
@@ -116,7 +116,7 @@ Value FunctionExpression::instantiate_ordinary_function_expression(VM& vm, Depre
     return closure;
 }
 
-Optional<DeprecatedString> CallExpression::expression_string() const
+Optional<ByteString> CallExpression::expression_string() const
 {
     if (is<Identifier>(*m_callee))
         return static_cast<Identifier const&>(*m_callee).string();
@@ -157,23 +157,23 @@ ThrowCompletionOr<ClassElement::ClassValue> ClassMethod::class_element_evaluatio
     auto& method_function = static_cast<ECMAScriptFunctionObject&>(method_value.as_function());
     method_function.make_method(target);
 
-    auto set_function_name = [&](DeprecatedString prefix = "") {
+    auto set_function_name = [&](ByteString prefix = "") {
         auto name = property_key_or_private_name.visit(
-            [&](PropertyKey const& property_key) -> DeprecatedString {
+            [&](PropertyKey const& property_key) -> ByteString {
                 if (property_key.is_symbol()) {
                     auto description = property_key.as_symbol()->description();
                     if (!description.has_value() || description->is_empty())
                         return "";
-                    return DeprecatedString::formatted("[{}]", *description);
+                    return ByteString::formatted("[{}]", *description);
                 } else {
                     return property_key.to_string();
                 }
             },
-            [&](PrivateName const& private_name) -> DeprecatedString {
+            [&](PrivateName const& private_name) -> ByteString {
                 return private_name.description;
             });
 
-        update_function_name(method_value, DeprecatedString::formatted("{}{}{}", prefix, prefix.is_empty() ? "" : " ", name));
+        update_function_name(method_value, ByteString::formatted("{}{}{}", prefix, prefix.is_empty() ? "" : " ", name));
     };
 
     if (property_key_or_private_name.has<PropertyKey>()) {
@@ -230,16 +230,16 @@ ThrowCompletionOr<ClassElement::ClassValue> ClassField::class_element_evaluation
     if (m_initializer) {
         auto copy_initializer = m_initializer;
         auto name = property_key_or_private_name.visit(
-            [&](PropertyKey const& property_key) -> DeprecatedString {
+            [&](PropertyKey const& property_key) -> ByteString {
                 return property_key.is_number() ? property_key.to_string() : property_key.to_string_or_symbol().to_display_string();
             },
-            [&](PrivateName const& private_name) -> DeprecatedString {
+            [&](PrivateName const& private_name) -> ByteString {
                 return private_name.description;
             });
 
         // FIXME: A potential optimization is not creating the functions here since these are never directly accessible.
         auto function_code = create_ast_node<ClassFieldInitializerStatement>(m_initializer->source_range(), copy_initializer.release_nonnull(), name);
-        initializer = make_handle(*ECMAScriptFunctionObject::create(realm, DeprecatedString::empty(), DeprecatedString::empty(), *function_code, {}, 0, {}, vm.lexical_environment(), vm.running_execution_context().private_environment, FunctionKind::Normal, true, false, m_contains_direct_call_to_eval, false, property_key_or_private_name));
+        initializer = make_handle(*ECMAScriptFunctionObject::create(realm, ByteString::empty(), ByteString::empty(), *function_code, {}, 0, {}, vm.lexical_environment(), vm.running_execution_context().private_environment, FunctionKind::Normal, true, false, m_contains_direct_call_to_eval, false, property_key_or_private_name));
         initializer->make_method(target);
     }
 
@@ -283,7 +283,7 @@ ThrowCompletionOr<ClassElement::ClassValue> StaticInitializer::class_element_eva
     // 4. Let formalParameters be an instance of the production FormalParameters : [empty] .
     // 5. Let bodyFunction be OrdinaryFunctionCreate(%Function.prototype%, sourceText, formalParameters, ClassStaticBlockBody, non-lexical-this, lex, privateEnv).
     // Note: The function bodyFunction is never directly accessible to ECMAScript code.
-    auto body_function = ECMAScriptFunctionObject::create(realm, DeprecatedString::empty(), DeprecatedString::empty(), *m_function_body, {}, 0, m_function_body->local_variables_names(), lexical_environment, private_environment, FunctionKind::Normal, true, false, m_contains_direct_call_to_eval, false);
+    auto body_function = ECMAScriptFunctionObject::create(realm, ByteString::empty(), ByteString::empty(), *m_function_body, {}, 0, m_function_body->local_variables_names(), lexical_environment, private_environment, FunctionKind::Normal, true, false, m_contains_direct_call_to_eval, false);
 
     // 6. Perform MakeMethod(bodyFunction, homeObject).
     body_function->make_method(home_object);
@@ -868,7 +868,7 @@ void BindingPattern::dump(int indent) const
     }
 }
 
-void FunctionNode::dump(int indent, DeprecatedString const& class_name) const
+void FunctionNode::dump(int indent, ByteString const& class_name) const
 {
     print_indent(indent);
     auto is_async = m_kind == FunctionKind::Async || m_kind == FunctionKind::AsyncGenerator;
@@ -1253,16 +1253,16 @@ void MemberExpression::dump(int indent) const
     m_property->dump(indent + 1);
 }
 
-DeprecatedString MemberExpression::to_string_approximation() const
+ByteString MemberExpression::to_string_approximation() const
 {
-    DeprecatedString object_string = "<object>";
+    ByteString object_string = "<object>";
     if (is<Identifier>(*m_object))
         object_string = static_cast<Identifier const&>(*m_object).string();
     if (is_computed())
-        return DeprecatedString::formatted("{}[<computed>]", object_string);
+        return ByteString::formatted("{}[<computed>]", object_string);
     if (is<PrivateIdentifier>(*m_property))
-        return DeprecatedString::formatted("{}.{}", object_string, verify_cast<PrivateIdentifier>(*m_property).string());
-    return DeprecatedString::formatted("{}.{}", object_string, verify_cast<Identifier>(*m_property).string());
+        return ByteString::formatted("{}.{}", object_string, verify_cast<PrivateIdentifier>(*m_property).string());
+    return ByteString::formatted("{}.{}", object_string, verify_cast<Identifier>(*m_property).string());
 }
 
 bool MemberExpression::ends_in_private_name() const
@@ -1309,7 +1309,7 @@ void OptionalChain::dump(int indent) const
 
 void MetaProperty::dump(int indent) const
 {
-    DeprecatedString name;
+    ByteString name;
     if (m_type == MetaProperty::Type::NewTarget)
         name = "new.target";
     else if (m_type == MetaProperty::Type::ImportMeta)
@@ -1550,11 +1550,11 @@ void ExportStatement::dump(int indent) const
     print_indent(indent + 1);
     outln("(ExportEntries)");
 
-    auto string_or_null = [](DeprecatedString const& string) -> DeprecatedString {
+    auto string_or_null = [](ByteString const& string) -> ByteString {
         if (string.is_empty()) {
             return "null";
         }
-        return DeprecatedString::formatted("\"{}\"", string);
+        return ByteString::formatted("\"{}\"", string);
     };
 
     for (auto& entry : m_entries) {
@@ -1895,9 +1895,9 @@ ModuleRequest::ModuleRequest(DeprecatedFlyString module_specifier_, Vector<Impor
     });
 }
 
-DeprecatedString SourceRange::filename() const
+ByteString SourceRange::filename() const
 {
-    return code->filename().to_deprecated_string();
+    return code->filename().to_byte_string();
 }
 
 NonnullRefPtr<CallExpression> CallExpression::create(SourceRange source_range, NonnullRefPtr<Expression const> callee, ReadonlySpan<Argument> arguments, InvocationStyleEnum invocation_style, InsideParenthesesEnum inside_parens)
diff --git a/Userland/Libraries/LibJS/AST.h b/Userland/Libraries/LibJS/AST.h
index 1936e86f65d..df33c271490 100644
--- a/Userland/Libraries/LibJS/AST.h
+++ b/Userland/Libraries/LibJS/AST.h
@@ -8,8 +8,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/DeprecatedFlyString.h>
-#include <AK/DeprecatedString.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/RefPtr.h>
@@ -69,7 +69,7 @@ public:
 
     void set_end_offset(Badge<Parser>, u32 end_offset) { m_end_offset = end_offset; }
 
-    DeprecatedString class_name() const;
+    ByteString class_name() const;
 
     template<typename T>
     bool fast_is() const = delete;
@@ -692,7 +692,7 @@ class FunctionNode {
 public:
     StringView name() const { return m_name ? m_name->string().view() : ""sv; }
     RefPtr<Identifier const> name_identifier() const { return m_name; }
-    DeprecatedString const& source_text() const { return m_source_text; }
+    ByteString const& source_text() const { return m_source_text; }
     Statement const& body() const { return *m_body; }
     Vector<FunctionParameter> const& parameters() const { return m_parameters; }
     i32 function_length() const { return m_function_length; }
@@ -704,7 +704,7 @@ public:
     FunctionKind kind() const { return m_kind; }
 
 protected:
-    FunctionNode(RefPtr<Identifier const> name, DeprecatedString source_text, NonnullRefPtr<Statement const> body, Vector<FunctionParameter> parameters, i32 function_length, FunctionKind kind, bool is_strict_mode, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Vector<DeprecatedFlyString> local_variables_names)
+    FunctionNode(RefPtr<Identifier const> name, ByteString source_text, NonnullRefPtr<Statement const> body, Vector<FunctionParameter> parameters, i32 function_length, FunctionKind kind, bool is_strict_mode, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Vector<DeprecatedFlyString> local_variables_names)
         : m_name(move(name))
         , m_source_text(move(source_text))
         , m_body(move(body))
@@ -721,12 +721,12 @@ protected:
             VERIFY(!m_might_need_arguments_object);
     }
 
-    void dump(int indent, DeprecatedString const& class_name) const;
+    void dump(int indent, ByteString const& class_name) const;
 
     RefPtr<Identifier const> m_name { nullptr };
 
 private:
-    DeprecatedString m_source_text;
+    ByteString m_source_text;
     NonnullRefPtr<Statement const> m_body;
     Vector<FunctionParameter> const m_parameters;
     i32 const m_function_length;
@@ -745,7 +745,7 @@ class FunctionDeclaration final
 public:
     static bool must_have_name() { return true; }
 
-    FunctionDeclaration(SourceRange source_range, RefPtr<Identifier const> name, DeprecatedString source_text, NonnullRefPtr<Statement const> body, Vector<FunctionParameter> parameters, i32 function_length, FunctionKind kind, bool is_strict_mode, bool might_need_arguments_object, bool contains_direct_call_to_eval, Vector<DeprecatedFlyString> local_variables_names)
+    FunctionDeclaration(SourceRange source_range, RefPtr<Identifier const> name, ByteString source_text, NonnullRefPtr<Statement const> body, Vector<FunctionParameter> parameters, i32 function_length, FunctionKind kind, bool is_strict_mode, bool might_need_arguments_object, bool contains_direct_call_to_eval, Vector<DeprecatedFlyString> local_variables_names)
         : Declaration(move(source_range))
         , FunctionNode(move(name), move(source_text), move(body), move(parameters), function_length, kind, is_strict_mode, might_need_arguments_object, contains_direct_call_to_eval, false, move(local_variables_names))
     {
@@ -770,7 +770,7 @@ class FunctionExpression final
 public:
     static bool must_have_name() { return false; }
 
-    FunctionExpression(SourceRange source_range, RefPtr<Identifier const> name, DeprecatedString source_text, NonnullRefPtr<Statement const> body, Vector<FunctionParameter> parameters, i32 function_length, FunctionKind kind, bool is_strict_mode, bool might_need_arguments_object, bool contains_direct_call_to_eval, Vector<DeprecatedFlyString> local_variables_names, bool is_arrow_function = false)
+    FunctionExpression(SourceRange source_range, RefPtr<Identifier const> name, ByteString source_text, NonnullRefPtr<Statement const> body, Vector<FunctionParameter> parameters, i32 function_length, FunctionKind kind, bool is_strict_mode, bool might_need_arguments_object, bool contains_direct_call_to_eval, Vector<DeprecatedFlyString> local_variables_names, bool is_arrow_function = false)
         : Expression(move(source_range))
         , FunctionNode(move(name), move(source_text), move(body), move(parameters), function_length, kind, is_strict_mode, might_need_arguments_object, contains_direct_call_to_eval, is_arrow_function, move(local_variables_names))
     {
@@ -1188,7 +1188,7 @@ private:
 
 class BigIntLiteral final : public Expression {
 public:
-    explicit BigIntLiteral(SourceRange source_range, DeprecatedString value)
+    explicit BigIntLiteral(SourceRange source_range, ByteString value)
         : Expression(move(source_range))
         , m_value(move(value))
     {
@@ -1198,12 +1198,12 @@ public:
     virtual Bytecode::CodeGenerationErrorOr<void> generate_bytecode(Bytecode::Generator&) const override;
 
 private:
-    DeprecatedString m_value;
+    ByteString m_value;
 };
 
 class StringLiteral final : public Expression {
 public:
-    explicit StringLiteral(SourceRange source_range, DeprecatedString value)
+    explicit StringLiteral(SourceRange source_range, ByteString value)
         : Expression(move(source_range))
         , m_value(move(value))
     {
@@ -1217,7 +1217,7 @@ public:
 private:
     virtual bool is_string_literal() const override { return true; }
 
-    DeprecatedString m_value;
+    ByteString m_value;
 };
 
 class NullLiteral final : public PrimitiveLiteral {
@@ -1235,7 +1235,7 @@ public:
 
 class RegExpLiteral final : public Expression {
 public:
-    RegExpLiteral(SourceRange source_range, regex::Parser::Result parsed_regex, DeprecatedString parsed_pattern, regex::RegexOptions<ECMAScriptFlags> parsed_flags, DeprecatedString pattern, DeprecatedString flags)
+    RegExpLiteral(SourceRange source_range, regex::Parser::Result parsed_regex, ByteString parsed_pattern, regex::RegexOptions<ECMAScriptFlags> parsed_flags, ByteString pattern, ByteString flags)
         : Expression(move(source_range))
         , m_parsed_regex(move(parsed_regex))
         , m_parsed_pattern(move(parsed_pattern))
@@ -1249,17 +1249,17 @@ public:
     virtual Bytecode::CodeGenerationErrorOr<void> generate_bytecode(Bytecode::Generator&) const override;
 
     regex::Parser::Result const& parsed_regex() const { return m_parsed_regex; }
-    DeprecatedString const& parsed_pattern() const { return m_parsed_pattern; }
+    ByteString const& parsed_pattern() const { return m_parsed_pattern; }
     regex::RegexOptions<ECMAScriptFlags> const& parsed_flags() const { return m_parsed_flags; }
-    DeprecatedString const& pattern() const { return m_pattern; }
-    DeprecatedString const& flags() const { return m_flags; }
+    ByteString const& pattern() const { return m_pattern; }
+    ByteString const& flags() const { return m_flags; }
 
 private:
     regex::Parser::Result m_parsed_regex;
-    DeprecatedString m_parsed_pattern;
+    ByteString m_parsed_pattern;
     regex::RegexOptions<ECMAScriptFlags> m_parsed_flags;
-    DeprecatedString m_pattern;
-    DeprecatedString m_flags;
+    ByteString m_pattern;
+    ByteString m_flags;
 };
 
 class PrivateIdentifier final : public Expression {
@@ -1398,7 +1398,7 @@ public:
 
 class ClassExpression final : public Expression {
 public:
-    ClassExpression(SourceRange source_range, RefPtr<Identifier const> name, DeprecatedString source_text, RefPtr<FunctionExpression const> constructor, RefPtr<Expression const> super_class, Vector<NonnullRefPtr<ClassElement const>> elements)
+    ClassExpression(SourceRange source_range, RefPtr<Identifier const> name, ByteString source_text, RefPtr<FunctionExpression const> constructor, RefPtr<Expression const> super_class, Vector<NonnullRefPtr<ClassElement const>> elements)
         : Expression(move(source_range))
         , m_name(move(name))
         , m_source_text(move(source_text))
@@ -1410,7 +1410,7 @@ public:
 
     StringView name() const { return m_name ? m_name->string().view() : ""sv; }
 
-    DeprecatedString const& source_text() const { return m_source_text; }
+    ByteString const& source_text() const { return m_source_text; }
     RefPtr<FunctionExpression const> constructor() const { return m_constructor; }
 
     virtual void dump(int indent) const override;
@@ -1428,7 +1428,7 @@ private:
     friend ClassDeclaration;
 
     RefPtr<Identifier const> m_name;
-    DeprecatedString m_source_text;
+    ByteString m_source_text;
     RefPtr<FunctionExpression const> m_constructor;
     RefPtr<Expression const> m_super_class;
     Vector<NonnullRefPtr<ClassElement const>> m_elements;
@@ -1551,7 +1551,7 @@ protected:
 
     virtual bool is_call_expression() const override { return true; }
 
-    Optional<DeprecatedString> expression_string() const;
+    Optional<ByteString> expression_string() const;
 
     NonnullRefPtr<Expression const> m_callee;
 };
@@ -1900,7 +1900,7 @@ public:
     Expression const& object() const { return *m_object; }
     Expression const& property() const { return *m_property; }
 
-    DeprecatedString to_string_approximation() const;
+    ByteString to_string_approximation() const;
 
     bool ends_in_private_name() const;
 
diff --git a/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp b/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
index 3e4de3e081c..6706599c697 100644
--- a/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
@@ -976,11 +976,11 @@ Bytecode::CodeGenerationErrorOr<void> ObjectExpression::generate_bytecode(Byteco
             if (property_kind == Bytecode::Op::PropertyKind::ProtoSetter) {
                 TRY(property->value().generate_bytecode(generator));
             } else if (property_kind != Bytecode::Op::PropertyKind::Spread) {
-                DeprecatedString identifier = string_literal.value();
+                ByteString identifier = string_literal.value();
                 if (property_kind == Bytecode::Op::PropertyKind::Getter)
-                    identifier = DeprecatedString::formatted("get {}", identifier);
+                    identifier = ByteString::formatted("get {}", identifier);
                 else if (property_kind == Bytecode::Op::PropertyKind::Setter)
-                    identifier = DeprecatedString::formatted("set {}", identifier);
+                    identifier = ByteString::formatted("set {}", identifier);
                 auto name = generator.intern_identifier(identifier);
                 TRY(generator.emit_named_evaluation_if_anonymous_function(property->value(), name));
             }
diff --git a/Userland/Libraries/LibJS/Bytecode/BasicBlock.cpp b/Userland/Libraries/LibJS/Bytecode/BasicBlock.cpp
index 71b8214988d..8a30a111d45 100644
--- a/Userland/Libraries/LibJS/Bytecode/BasicBlock.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/BasicBlock.cpp
@@ -46,7 +46,7 @@ void BasicBlock::dump(Bytecode::Executable const& executable) const
     }
     warnln(":");
     while (!it.at_end()) {
-        warnln("[{:4x}] {}", it.offset(), (*it).to_deprecated_string(executable));
+        warnln("[{:4x}] {}", it.offset(), (*it).to_byte_string(executable));
         ++it;
     }
 }
diff --git a/Userland/Libraries/LibJS/Bytecode/CommonImplementations.cpp b/Userland/Libraries/LibJS/Bytecode/CommonImplementations.cpp
index a0093f287a0..bbf50e27b7c 100644
--- a/Userland/Libraries/LibJS/Bytecode/CommonImplementations.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/CommonImplementations.cpp
@@ -225,14 +225,14 @@ ThrowCompletionOr<void> put_by_property_key(VM& vm, Value base, Value this_value
     case Op::PropertyKind::Getter: {
         auto& function = value.as_function();
         if (function.name().is_empty() && is<ECMAScriptFunctionObject>(function))
-            static_cast<ECMAScriptFunctionObject*>(&function)->set_name(DeprecatedString::formatted("get {}", name));
+            static_cast<ECMAScriptFunctionObject*>(&function)->set_name(ByteString::formatted("get {}", name));
         object->define_direct_accessor(name, &function, nullptr, Attribute::Configurable | Attribute::Enumerable);
         break;
     }
     case Op::PropertyKind::Setter: {
         auto& function = value.as_function();
         if (function.name().is_empty() && is<ECMAScriptFunctionObject>(function))
-            static_cast<ECMAScriptFunctionObject*>(&function)->set_name(DeprecatedString::formatted("set {}", name));
+            static_cast<ECMAScriptFunctionObject*>(&function)->set_name(ByteString::formatted("set {}", name));
         object->define_direct_accessor(name, nullptr, &function, Attribute::Configurable | Attribute::Enumerable);
         break;
     }
@@ -511,7 +511,7 @@ ThrowCompletionOr<CalleeAndThis> get_callee_and_this_from_environment(Bytecode::
 }
 
 // 13.2.7.3 Runtime Semantics: Evaluation, https://tc39.es/ecma262/#sec-regular-expression-literals-runtime-semantics-evaluation
-Value new_regexp(VM& vm, ParsedRegex const& parsed_regex, DeprecatedString const& pattern, DeprecatedString const& flags)
+Value new_regexp(VM& vm, ParsedRegex const& parsed_regex, ByteString const& pattern, ByteString const& flags)
 {
     // 1. Let pattern be CodePointsToString(BodyText of RegularExpressionLiteral).
     // 2. Let flags be CodePointsToString(FlagText of RegularExpressionLiteral).
diff --git a/Userland/Libraries/LibJS/Bytecode/CommonImplementations.h b/Userland/Libraries/LibJS/Bytecode/CommonImplementations.h
index 242d0dfa5e8..7bb599a9836 100644
--- a/Userland/Libraries/LibJS/Bytecode/CommonImplementations.h
+++ b/Userland/Libraries/LibJS/Bytecode/CommonImplementations.h
@@ -30,7 +30,7 @@ struct CalleeAndThis {
     Value this_value;
 };
 ThrowCompletionOr<CalleeAndThis> get_callee_and_this_from_environment(Bytecode::Interpreter&, DeprecatedFlyString const& name, EnvironmentVariableCache&);
-Value new_regexp(VM&, ParsedRegex const&, DeprecatedString const& pattern, DeprecatedString const& flags);
+Value new_regexp(VM&, ParsedRegex const&, ByteString const& pattern, ByteString const& flags);
 MarkedVector<Value> argument_list_evaluation(VM&, Value arguments);
 ThrowCompletionOr<void> create_variable(VM&, DeprecatedFlyString const& name, Op::EnvironmentMode, bool is_global, bool is_immutable, bool is_strict);
 ThrowCompletionOr<ECMAScriptFunctionObject*> new_class(VM&, Value super_class, ClassExpression const&, Optional<IdentifierTableIndex> const& lhs_name);
diff --git a/Userland/Libraries/LibJS/Bytecode/Executable.h b/Userland/Libraries/LibJS/Bytecode/Executable.h
index b6ab1e26d66..5e23335ca3d 100644
--- a/Userland/Libraries/LibJS/Bytecode/Executable.h
+++ b/Userland/Libraries/LibJS/Bytecode/Executable.h
@@ -78,7 +78,7 @@ public:
     size_t number_of_registers { 0 };
     bool is_strict_mode { false };
 
-    DeprecatedString const& get_string(StringTableIndex index) const { return string_table->get(index); }
+    ByteString const& get_string(StringTableIndex index) const { return string_table->get(index); }
     DeprecatedFlyString const& get_identifier(IdentifierTableIndex index) const { return identifier_table->get(index); }
 
     void dump() const;
diff --git a/Userland/Libraries/LibJS/Bytecode/Generator.h b/Userland/Libraries/LibJS/Bytecode/Generator.h
index 3dbd7a9cadf..1f1a913d1d5 100644
--- a/Userland/Libraries/LibJS/Bytecode/Generator.h
+++ b/Userland/Libraries/LibJS/Bytecode/Generator.h
@@ -152,7 +152,7 @@ public:
         return m_current_basic_block->is_terminated();
     }
 
-    StringTableIndex intern_string(DeprecatedString string)
+    StringTableIndex intern_string(ByteString string)
     {
         return m_string_table->insert(move(string));
     }
diff --git a/Userland/Libraries/LibJS/Bytecode/Instruction.h b/Userland/Libraries/LibJS/Bytecode/Instruction.h
index 80dd9339513..b0a6b37cf8f 100644
--- a/Userland/Libraries/LibJS/Bytecode/Instruction.h
+++ b/Userland/Libraries/LibJS/Bytecode/Instruction.h
@@ -135,7 +135,7 @@ public:
 
     Type type() const { return m_type; }
     size_t length() const { return m_length; }
-    DeprecatedString to_deprecated_string(Bytecode::Executable const&) const;
+    ByteString to_byte_string(Bytecode::Executable const&) const;
     ThrowCompletionOr<void> execute(Bytecode::Interpreter&) const;
     static void destroy(Instruction&);
 
diff --git a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
index 048298968c7..a07f3946d52 100644
--- a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
@@ -502,11 +502,11 @@ Variant<NonnullOwnPtr<CallFrame>, CallFrame*> Interpreter::pop_call_frame()
 
 namespace JS::Bytecode {
 
-DeprecatedString Instruction::to_deprecated_string(Bytecode::Executable const& executable) const
+ByteString Instruction::to_byte_string(Bytecode::Executable const& executable) const
 {
 #define __BYTECODE_OP(op)       \
     case Instruction::Type::op: \
-        return static_cast<Bytecode::Op::op const&>(*this).to_deprecated_string_impl(executable);
+        return static_cast<Bytecode::Op::op const&>(*this).to_byte_string_impl(executable);
 
     switch (type()) {
         ENUMERATE_BYTECODE_OPS(__BYTECODE_OP)
@@ -568,9 +568,9 @@ static ThrowCompletionOr<Value> strict_equals(VM&, Value src1, Value src2)
         interpreter.accumulator() = TRY(op_snake_case(vm, lhs, rhs));                           \
         return {};                                                                              \
     }                                                                                           \
-    DeprecatedString OpTitleCase::to_deprecated_string_impl(Bytecode::Executable const&) const  \
+    ByteString OpTitleCase::to_byte_string_impl(Bytecode::Executable const&) const              \
     {                                                                                           \
-        return DeprecatedString::formatted(#OpTitleCase " {}", m_lhs_reg);                      \
+        return ByteString::formatted(#OpTitleCase " {}", m_lhs_reg);                            \
     }
 
 JS_ENUMERATE_COMMON_BINARY_OPS(JS_DEFINE_COMMON_BINARY_OP)
@@ -592,7 +592,7 @@ static ThrowCompletionOr<Value> typeof_(VM& vm, Value value)
         interpreter.accumulator() = TRY(op_snake_case(vm, interpreter.accumulator()));          \
         return {};                                                                              \
     }                                                                                           \
-    DeprecatedString OpTitleCase::to_deprecated_string_impl(Bytecode::Executable const&) const  \
+    ByteString OpTitleCase::to_byte_string_impl(Bytecode::Executable const&) const              \
     {                                                                                           \
         return #OpTitleCase;                                                                    \
     }
@@ -671,17 +671,17 @@ ThrowCompletionOr<void> NewRegExp::execute_impl(Bytecode::Interpreter& interpret
     return {};
 }
 
-#define JS_DEFINE_NEW_BUILTIN_ERROR_OP(ErrorName)                                                                                          \
-    ThrowCompletionOr<void> New##ErrorName::execute_impl(Bytecode::Interpreter& interpreter) const                                         \
-    {                                                                                                                                      \
-        auto& vm = interpreter.vm();                                                                                                       \
-        auto& realm = *vm.current_realm();                                                                                                 \
-        interpreter.accumulator() = ErrorName::create(realm, interpreter.current_executable().get_string(m_error_string));                 \
-        return {};                                                                                                                         \
-    }                                                                                                                                      \
-    DeprecatedString New##ErrorName::to_deprecated_string_impl(Bytecode::Executable const& executable) const                               \
-    {                                                                                                                                      \
-        return DeprecatedString::formatted("New" #ErrorName " {} (\"{}\")", m_error_string, executable.string_table->get(m_error_string)); \
+#define JS_DEFINE_NEW_BUILTIN_ERROR_OP(ErrorName)                                                                                    \
+    ThrowCompletionOr<void> New##ErrorName::execute_impl(Bytecode::Interpreter& interpreter) const                                   \
+    {                                                                                                                                \
+        auto& vm = interpreter.vm();                                                                                                 \
+        auto& realm = *vm.current_realm();                                                                                           \
+        interpreter.accumulator() = ErrorName::create(realm, interpreter.current_executable().get_string(m_error_string));           \
+        return {};                                                                                                                   \
+    }                                                                                                                                \
+    ByteString New##ErrorName::to_byte_string_impl(Bytecode::Executable const& executable) const                                     \
+    {                                                                                                                                \
+        return ByteString::formatted("New" #ErrorName " {} (\"{}\")", m_error_string, executable.string_table->get(m_error_string)); \
     }
 
 JS_ENUMERATE_NEW_BUILTIN_ERROR_OPS(JS_DEFINE_NEW_BUILTIN_ERROR_OP)
@@ -1325,69 +1325,69 @@ ThrowCompletionOr<void> BlockDeclarationInstantiation::execute_impl(Bytecode::In
     return {};
 }
 
-DeprecatedString Load::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Load::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("Load {}", m_src);
+    return ByteString::formatted("Load {}", m_src);
 }
 
-DeprecatedString LoadImmediate::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString LoadImmediate::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("LoadImmediate {}", m_value);
+    return ByteString::formatted("LoadImmediate {}", m_value);
 }
 
-DeprecatedString Store::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Store::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("Store {}", m_dst);
+    return ByteString::formatted("Store {}", m_dst);
 }
 
-DeprecatedString NewBigInt::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString NewBigInt::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("NewBigInt \"{}\"", m_bigint.to_base_deprecated(10));
+    return ByteString::formatted("NewBigInt \"{}\"", m_bigint.to_base_deprecated(10));
 }
 
-DeprecatedString NewArray::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString NewArray::to_byte_string_impl(Bytecode::Executable const&) const
 {
     StringBuilder builder;
     builder.append("NewArray"sv);
     if (m_element_count != 0) {
         builder.appendff(" [{}-{}]", m_elements[0], m_elements[1]);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString NewPrimitiveArray::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString NewPrimitiveArray::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("NewPrimitiveArray {}"sv, m_values.span());
+    return ByteString::formatted("NewPrimitiveArray {}"sv, m_values.span());
 }
 
-DeprecatedString Append::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Append::to_byte_string_impl(Bytecode::Executable const&) const
 {
     if (m_is_spread)
-        return DeprecatedString::formatted("Append lhs: **{}", m_lhs);
-    return DeprecatedString::formatted("Append lhs: {}", m_lhs);
+        return ByteString::formatted("Append lhs: **{}", m_lhs);
+    return ByteString::formatted("Append lhs: {}", m_lhs);
 }
 
-DeprecatedString IteratorToArray::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString IteratorToArray::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "IteratorToArray";
 }
 
-DeprecatedString NewString::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString NewString::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("NewString {} (\"{}\")", m_string, executable.string_table->get(m_string));
+    return ByteString::formatted("NewString {} (\"{}\")", m_string, executable.string_table->get(m_string));
 }
 
-DeprecatedString NewObject::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString NewObject::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "NewObject";
 }
 
-DeprecatedString NewRegExp::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString NewRegExp::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("NewRegExp source:{} (\"{}\") flags:{} (\"{}\")", m_source_index, executable.get_string(m_source_index), m_flags_index, executable.get_string(m_flags_index));
+    return ByteString::formatted("NewRegExp source:{} (\"{}\") flags:{} (\"{}\")", m_source_index, executable.get_string(m_source_index), m_flags_index, executable.get_string(m_flags_index));
 }
 
-DeprecatedString CopyObjectExcludingProperties::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString CopyObjectExcludingProperties::to_byte_string_impl(Bytecode::Executable const&) const
 {
     StringBuilder builder;
     builder.appendff("CopyObjectExcludingProperties from:{}", m_from_object);
@@ -1396,65 +1396,65 @@ DeprecatedString CopyObjectExcludingProperties::to_deprecated_string_impl(Byteco
         builder.join(", "sv, ReadonlySpan<Register>(m_excluded_names, m_excluded_names_count));
         builder.append(']');
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString ConcatString::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString ConcatString::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("ConcatString {}", m_lhs);
+    return ByteString::formatted("ConcatString {}", m_lhs);
 }
 
-DeprecatedString GetCalleeAndThisFromEnvironment::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString GetCalleeAndThisFromEnvironment::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("GetCalleeAndThisFromEnvironment {} -> callee: {}, this:{} ", executable.identifier_table->get(m_identifier), m_callee_reg, m_this_reg);
+    return ByteString::formatted("GetCalleeAndThisFromEnvironment {} -> callee: {}, this:{} ", executable.identifier_table->get(m_identifier), m_callee_reg, m_this_reg);
 }
 
-DeprecatedString GetVariable::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString GetVariable::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("GetVariable {} ({})", m_identifier, executable.identifier_table->get(m_identifier));
+    return ByteString::formatted("GetVariable {} ({})", m_identifier, executable.identifier_table->get(m_identifier));
 }
 
-DeprecatedString GetGlobal::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString GetGlobal::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("GetGlobal {} ({})", m_identifier, executable.identifier_table->get(m_identifier));
+    return ByteString::formatted("GetGlobal {} ({})", m_identifier, executable.identifier_table->get(m_identifier));
 }
 
-DeprecatedString GetLocal::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString GetLocal::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("GetLocal {}", m_index);
+    return ByteString::formatted("GetLocal {}", m_index);
 }
 
-DeprecatedString DeleteVariable::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString DeleteVariable::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("DeleteVariable {} ({})", m_identifier, executable.identifier_table->get(m_identifier));
+    return ByteString::formatted("DeleteVariable {} ({})", m_identifier, executable.identifier_table->get(m_identifier));
 }
 
-DeprecatedString CreateLexicalEnvironment::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString CreateLexicalEnvironment::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "CreateLexicalEnvironment"sv;
 }
 
-DeprecatedString CreateVariable::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString CreateVariable::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
     auto mode_string = m_mode == EnvironmentMode::Lexical ? "Lexical" : "Variable";
-    return DeprecatedString::formatted("CreateVariable env:{} immutable:{} global:{} {} ({})", mode_string, m_is_immutable, m_is_global, m_identifier, executable.identifier_table->get(m_identifier));
+    return ByteString::formatted("CreateVariable env:{} immutable:{} global:{} {} ({})", mode_string, m_is_immutable, m_is_global, m_identifier, executable.identifier_table->get(m_identifier));
 }
 
-DeprecatedString EnterObjectEnvironment::to_deprecated_string_impl(Executable const&) const
+ByteString EnterObjectEnvironment::to_byte_string_impl(Executable const&) const
 {
-    return DeprecatedString::formatted("EnterObjectEnvironment");
+    return ByteString::formatted("EnterObjectEnvironment");
 }
 
-DeprecatedString SetVariable::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString SetVariable::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
     auto initialization_mode_name = m_initialization_mode == InitializationMode::Initialize ? "Initialize" : "Set";
     auto mode_string = m_mode == EnvironmentMode::Lexical ? "Lexical" : "Variable";
-    return DeprecatedString::formatted("SetVariable env:{} init:{} {} ({})", mode_string, initialization_mode_name, m_identifier, executable.identifier_table->get(m_identifier));
+    return ByteString::formatted("SetVariable env:{} init:{} {} ({})", mode_string, initialization_mode_name, m_identifier, executable.identifier_table->get(m_identifier));
 }
 
-DeprecatedString SetLocal::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString SetLocal::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("SetLocal {}", m_index);
+    return ByteString::formatted("SetLocal {}", m_index);
 }
 
 static StringView property_kind_to_string(PropertyKind kind)
@@ -1476,80 +1476,80 @@ static StringView property_kind_to_string(PropertyKind kind)
     VERIFY_NOT_REACHED();
 }
 
-DeprecatedString PutById::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString PutById::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
     auto kind = property_kind_to_string(m_kind);
-    return DeprecatedString::formatted("PutById kind:{} base:{}, property:{} ({})", kind, m_base, m_property, executable.identifier_table->get(m_property));
+    return ByteString::formatted("PutById kind:{} base:{}, property:{} ({})", kind, m_base, m_property, executable.identifier_table->get(m_property));
 }
 
-DeprecatedString PutByIdWithThis::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString PutByIdWithThis::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
     auto kind = property_kind_to_string(m_kind);
-    return DeprecatedString::formatted("PutByIdWithThis kind:{} base:{}, property:{} ({}) this_value:{}", kind, m_base, m_property, executable.identifier_table->get(m_property), m_this_value);
+    return ByteString::formatted("PutByIdWithThis kind:{} base:{}, property:{} ({}) this_value:{}", kind, m_base, m_property, executable.identifier_table->get(m_property), m_this_value);
 }
 
-DeprecatedString PutPrivateById::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString PutPrivateById::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
     auto kind = property_kind_to_string(m_kind);
-    return DeprecatedString::formatted("PutPrivateById kind:{} base:{}, property:{} ({})", kind, m_base, m_property, executable.identifier_table->get(m_property));
+    return ByteString::formatted("PutPrivateById kind:{} base:{}, property:{} ({})", kind, m_base, m_property, executable.identifier_table->get(m_property));
 }
 
-DeprecatedString GetById::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString GetById::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("GetById {} ({})", m_property, executable.identifier_table->get(m_property));
+    return ByteString::formatted("GetById {} ({})", m_property, executable.identifier_table->get(m_property));
 }
 
-DeprecatedString GetByIdWithThis::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString GetByIdWithThis::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("GetByIdWithThis {} ({}) this_value:{}", m_property, executable.identifier_table->get(m_property), m_this_value);
+    return ByteString::formatted("GetByIdWithThis {} ({}) this_value:{}", m_property, executable.identifier_table->get(m_property), m_this_value);
 }
 
-DeprecatedString GetPrivateById::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString GetPrivateById::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("GetPrivateById {} ({})", m_property, executable.identifier_table->get(m_property));
+    return ByteString::formatted("GetPrivateById {} ({})", m_property, executable.identifier_table->get(m_property));
 }
 
-DeprecatedString HasPrivateId::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString HasPrivateId::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("HasPrivateId {} ({})", m_property, executable.identifier_table->get(m_property));
+    return ByteString::formatted("HasPrivateId {} ({})", m_property, executable.identifier_table->get(m_property));
 }
 
-DeprecatedString DeleteById::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString DeleteById::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("DeleteById {} ({})", m_property, executable.identifier_table->get(m_property));
+    return ByteString::formatted("DeleteById {} ({})", m_property, executable.identifier_table->get(m_property));
 }
 
-DeprecatedString DeleteByIdWithThis::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString DeleteByIdWithThis::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("DeleteByIdWithThis {} ({}) this_value:{}", m_property, executable.identifier_table->get(m_property), m_this_value);
+    return ByteString::formatted("DeleteByIdWithThis {} ({}) this_value:{}", m_property, executable.identifier_table->get(m_property), m_this_value);
 }
 
-DeprecatedString Jump::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Jump::to_byte_string_impl(Bytecode::Executable const&) const
 {
     if (m_true_target.has_value())
-        return DeprecatedString::formatted("Jump {}", *m_true_target);
-    return DeprecatedString::formatted("Jump <empty>");
+        return ByteString::formatted("Jump {}", *m_true_target);
+    return ByteString::formatted("Jump <empty>");
 }
 
-DeprecatedString JumpConditional::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString JumpConditional::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    auto true_string = m_true_target.has_value() ? DeprecatedString::formatted("{}", *m_true_target) : "<empty>";
-    auto false_string = m_false_target.has_value() ? DeprecatedString::formatted("{}", *m_false_target) : "<empty>";
-    return DeprecatedString::formatted("JumpConditional true:{} false:{}", true_string, false_string);
+    auto true_string = m_true_target.has_value() ? ByteString::formatted("{}", *m_true_target) : "<empty>";
+    auto false_string = m_false_target.has_value() ? ByteString::formatted("{}", *m_false_target) : "<empty>";
+    return ByteString::formatted("JumpConditional true:{} false:{}", true_string, false_string);
 }
 
-DeprecatedString JumpNullish::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString JumpNullish::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    auto true_string = m_true_target.has_value() ? DeprecatedString::formatted("{}", *m_true_target) : "<empty>";
-    auto false_string = m_false_target.has_value() ? DeprecatedString::formatted("{}", *m_false_target) : "<empty>";
-    return DeprecatedString::formatted("JumpNullish null:{} nonnull:{}", true_string, false_string);
+    auto true_string = m_true_target.has_value() ? ByteString::formatted("{}", *m_true_target) : "<empty>";
+    auto false_string = m_false_target.has_value() ? ByteString::formatted("{}", *m_false_target) : "<empty>";
+    return ByteString::formatted("JumpNullish null:{} nonnull:{}", true_string, false_string);
 }
 
-DeprecatedString JumpUndefined::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString JumpUndefined::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    auto true_string = m_true_target.has_value() ? DeprecatedString::formatted("{}", *m_true_target) : "<empty>";
-    auto false_string = m_false_target.has_value() ? DeprecatedString::formatted("{}", *m_false_target) : "<empty>";
-    return DeprecatedString::formatted("JumpUndefined undefined:{} not undefined:{}", true_string, false_string);
+    auto true_string = m_true_target.has_value() ? ByteString::formatted("{}", *m_true_target) : "<empty>";
+    auto false_string = m_false_target.has_value() ? ByteString::formatted("{}", *m_false_target) : "<empty>";
+    return ByteString::formatted("JumpUndefined undefined:{} not undefined:{}", true_string, false_string);
 }
 
 static StringView call_type_to_string(CallType type)
@@ -1565,30 +1565,30 @@ static StringView call_type_to_string(CallType type)
     VERIFY_NOT_REACHED();
 }
 
-DeprecatedString Call::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString Call::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
     auto type = call_type_to_string(m_type);
     if (m_builtin.has_value())
-        return DeprecatedString::formatted("Call{} callee:{}, this:{}, first_arg:{} (builtin {})", type, m_callee, m_this_value, m_first_argument, m_builtin.value());
+        return ByteString::formatted("Call{} callee:{}, this:{}, first_arg:{} (builtin {})", type, m_callee, m_this_value, m_first_argument, m_builtin.value());
     if (m_expression_string.has_value())
-        return DeprecatedString::formatted("Call{} callee:{}, this:{}, first_arg:{} ({})", type, m_callee, m_this_value, m_first_argument, executable.get_string(m_expression_string.value()));
-    return DeprecatedString::formatted("Call{} callee:{}, this:{}, first_arg:{}", type, m_callee, m_first_argument, m_this_value);
+        return ByteString::formatted("Call{} callee:{}, this:{}, first_arg:{} ({})", type, m_callee, m_this_value, m_first_argument, executable.get_string(m_expression_string.value()));
+    return ByteString::formatted("Call{} callee:{}, this:{}, first_arg:{}", type, m_callee, m_first_argument, m_this_value);
 }
 
-DeprecatedString CallWithArgumentArray::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString CallWithArgumentArray::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
     auto type = call_type_to_string(m_type);
     if (m_expression_string.has_value())
-        return DeprecatedString::formatted("CallWithArgumentArray{} callee:{}, this:{}, arguments:[...acc] ({})", type, m_callee, m_this_value, executable.get_string(m_expression_string.value()));
-    return DeprecatedString::formatted("CallWithArgumentArray{} callee:{}, this:{}, arguments:[...acc]", type, m_callee, m_this_value);
+        return ByteString::formatted("CallWithArgumentArray{} callee:{}, this:{}, arguments:[...acc] ({})", type, m_callee, m_this_value, executable.get_string(m_expression_string.value()));
+    return ByteString::formatted("CallWithArgumentArray{} callee:{}, this:{}, arguments:[...acc]", type, m_callee, m_this_value);
 }
 
-DeprecatedString SuperCallWithArgumentArray::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString SuperCallWithArgumentArray::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "SuperCallWithArgumentArray arguments:[...acc]"sv;
 }
 
-DeprecatedString NewFunction::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString NewFunction::to_byte_string_impl(Bytecode::Executable const&) const
 {
     StringBuilder builder;
     builder.append("NewFunction"sv);
@@ -1598,215 +1598,215 @@ DeprecatedString NewFunction::to_deprecated_string_impl(Bytecode::Executable con
         builder.appendff(" lhs_name:{}"sv, m_lhs_name.value());
     if (m_home_object.has_value())
         builder.appendff(" home_object:{}"sv, m_home_object.value());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString NewClass::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString NewClass::to_byte_string_impl(Bytecode::Executable const&) const
 {
     StringBuilder builder;
     auto name = m_class_expression.name();
     builder.appendff("NewClass '{}'"sv, name.is_null() ? ""sv : name);
     if (m_lhs_name.has_value())
         builder.appendff(" lhs_name:{}"sv, m_lhs_name.value());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Return::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Return::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "Return";
 }
 
-DeprecatedString Increment::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Increment::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "Increment";
 }
 
-DeprecatedString Decrement::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Decrement::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "Decrement";
 }
 
-DeprecatedString Throw::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Throw::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "Throw";
 }
 
-DeprecatedString ThrowIfNotObject::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString ThrowIfNotObject::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "ThrowIfNotObject";
 }
 
-DeprecatedString ThrowIfNullish::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString ThrowIfNullish::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "ThrowIfNullish";
 }
 
-DeprecatedString EnterUnwindContext::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString EnterUnwindContext::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("EnterUnwindContext entry:{}", m_entry_point);
+    return ByteString::formatted("EnterUnwindContext entry:{}", m_entry_point);
 }
 
-DeprecatedString ScheduleJump::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString ScheduleJump::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("ScheduleJump {}", m_target);
+    return ByteString::formatted("ScheduleJump {}", m_target);
 }
 
-DeprecatedString LeaveLexicalEnvironment::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString LeaveLexicalEnvironment::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "LeaveLexicalEnvironment"sv;
 }
 
-DeprecatedString LeaveUnwindContext::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString LeaveUnwindContext::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "LeaveUnwindContext";
 }
 
-DeprecatedString ContinuePendingUnwind::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString ContinuePendingUnwind::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("ContinuePendingUnwind resume:{}", m_resume_target);
+    return ByteString::formatted("ContinuePendingUnwind resume:{}", m_resume_target);
 }
 
-DeprecatedString Yield::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Yield::to_byte_string_impl(Bytecode::Executable const&) const
 {
     if (m_continuation_label.has_value())
-        return DeprecatedString::formatted("Yield continuation:@{}", m_continuation_label->block().name());
-    return DeprecatedString::formatted("Yield return");
+        return ByteString::formatted("Yield continuation:@{}", m_continuation_label->block().name());
+    return ByteString::formatted("Yield return");
 }
 
-DeprecatedString Await::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Await::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("Await continuation:@{}", m_continuation_label.block().name());
+    return ByteString::formatted("Await continuation:@{}", m_continuation_label.block().name());
 }
 
-DeprecatedString GetByValue::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString GetByValue::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("GetByValue base:{}", m_base);
+    return ByteString::formatted("GetByValue base:{}", m_base);
 }
 
-DeprecatedString GetByValueWithThis::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString GetByValueWithThis::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("GetByValueWithThis base:{} this_value:{}", m_base, m_this_value);
+    return ByteString::formatted("GetByValueWithThis base:{} this_value:{}", m_base, m_this_value);
 }
 
-DeprecatedString PutByValue::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString PutByValue::to_byte_string_impl(Bytecode::Executable const&) const
 {
     auto kind = property_kind_to_string(m_kind);
-    return DeprecatedString::formatted("PutByValue kind:{} base:{}, property:{}", kind, m_base, m_property);
+    return ByteString::formatted("PutByValue kind:{} base:{}, property:{}", kind, m_base, m_property);
 }
 
-DeprecatedString PutByValueWithThis::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString PutByValueWithThis::to_byte_string_impl(Bytecode::Executable const&) const
 {
     auto kind = property_kind_to_string(m_kind);
-    return DeprecatedString::formatted("PutByValueWithThis kind:{} base:{}, property:{} this_value:{}", kind, m_base, m_property, m_this_value);
+    return ByteString::formatted("PutByValueWithThis kind:{} base:{}, property:{} this_value:{}", kind, m_base, m_property, m_this_value);
 }
 
-DeprecatedString DeleteByValue::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString DeleteByValue::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("DeleteByValue base:{}", m_base);
+    return ByteString::formatted("DeleteByValue base:{}", m_base);
 }
 
-DeprecatedString DeleteByValueWithThis::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString DeleteByValueWithThis::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("DeleteByValueWithThis base:{} this_value:{}", m_base, m_this_value);
+    return ByteString::formatted("DeleteByValueWithThis base:{} this_value:{}", m_base, m_this_value);
 }
 
-DeprecatedString GetIterator::to_deprecated_string_impl(Executable const&) const
+ByteString GetIterator::to_byte_string_impl(Executable const&) const
 {
     auto hint = m_hint == IteratorHint::Sync ? "sync" : "async";
-    return DeprecatedString::formatted("GetIterator hint:{}", hint);
+    return ByteString::formatted("GetIterator hint:{}", hint);
 }
 
-DeprecatedString GetMethod::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString GetMethod::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("GetMethod {} ({})", m_property, executable.identifier_table->get(m_property));
+    return ByteString::formatted("GetMethod {} ({})", m_property, executable.identifier_table->get(m_property));
 }
 
-DeprecatedString GetObjectPropertyIterator::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString GetObjectPropertyIterator::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "GetObjectPropertyIterator";
 }
 
-DeprecatedString IteratorClose::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString IteratorClose::to_byte_string_impl(Bytecode::Executable const&) const
 {
     if (!m_completion_value.has_value())
-        return DeprecatedString::formatted("IteratorClose completion_type={} completion_value=<empty>", to_underlying(m_completion_type));
+        return ByteString::formatted("IteratorClose completion_type={} completion_value=<empty>", to_underlying(m_completion_type));
 
     auto completion_value_string = m_completion_value->to_string_without_side_effects();
-    return DeprecatedString::formatted("IteratorClose completion_type={} completion_value={}", to_underlying(m_completion_type), completion_value_string);
+    return ByteString::formatted("IteratorClose completion_type={} completion_value={}", to_underlying(m_completion_type), completion_value_string);
 }
 
-DeprecatedString AsyncIteratorClose::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString AsyncIteratorClose::to_byte_string_impl(Bytecode::Executable const&) const
 {
     if (!m_completion_value.has_value())
-        return DeprecatedString::formatted("AsyncIteratorClose completion_type={} completion_value=<empty>", to_underlying(m_completion_type));
+        return ByteString::formatted("AsyncIteratorClose completion_type={} completion_value=<empty>", to_underlying(m_completion_type));
 
     auto completion_value_string = m_completion_value->to_string_without_side_effects();
-    return DeprecatedString::formatted("AsyncIteratorClose completion_type={} completion_value={}", to_underlying(m_completion_type), completion_value_string);
+    return ByteString::formatted("AsyncIteratorClose completion_type={} completion_value={}", to_underlying(m_completion_type), completion_value_string);
 }
 
-DeprecatedString IteratorNext::to_deprecated_string_impl(Executable const&) const
+ByteString IteratorNext::to_byte_string_impl(Executable const&) const
 {
     return "IteratorNext";
 }
 
-DeprecatedString ResolveThisBinding::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString ResolveThisBinding::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "ResolveThisBinding"sv;
 }
 
-DeprecatedString ResolveSuperBase::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString ResolveSuperBase::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "ResolveSuperBase"sv;
 }
 
-DeprecatedString GetNewTarget::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString GetNewTarget::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "GetNewTarget"sv;
 }
 
-DeprecatedString GetImportMeta::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString GetImportMeta::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "GetImportMeta"sv;
 }
 
-DeprecatedString TypeofVariable::to_deprecated_string_impl(Bytecode::Executable const& executable) const
+ByteString TypeofVariable::to_byte_string_impl(Bytecode::Executable const& executable) const
 {
-    return DeprecatedString::formatted("TypeofVariable {} ({})", m_identifier, executable.identifier_table->get(m_identifier));
+    return ByteString::formatted("TypeofVariable {} ({})", m_identifier, executable.identifier_table->get(m_identifier));
 }
 
-DeprecatedString TypeofLocal::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString TypeofLocal::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("TypeofLocal {}", m_index);
+    return ByteString::formatted("TypeofLocal {}", m_index);
 }
 
-DeprecatedString ToNumeric::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString ToNumeric::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "ToNumeric"sv;
 }
 
-DeprecatedString BlockDeclarationInstantiation::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString BlockDeclarationInstantiation::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "BlockDeclarationInstantiation"sv;
 }
 
-DeprecatedString ImportCall::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString ImportCall::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("ImportCall specifier:{} options:{}"sv, m_specifier, m_options);
+    return ByteString::formatted("ImportCall specifier:{} options:{}"sv, m_specifier, m_options);
 }
 
-DeprecatedString Catch::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString Catch::to_byte_string_impl(Bytecode::Executable const&) const
 {
     return "Catch"sv;
 }
 
-DeprecatedString GetObjectFromIteratorRecord::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString GetObjectFromIteratorRecord::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("GetObjectFromIteratorRecord object:{} <- iterator_record:{}", m_object, m_iterator_record);
+    return ByteString::formatted("GetObjectFromIteratorRecord object:{} <- iterator_record:{}", m_object, m_iterator_record);
 }
 
-DeprecatedString GetNextMethodFromIteratorRecord::to_deprecated_string_impl(Bytecode::Executable const&) const
+ByteString GetNextMethodFromIteratorRecord::to_byte_string_impl(Bytecode::Executable const&) const
 {
-    return DeprecatedString::formatted("GetNextMethodFromIteratorRecord next_method:{} <- iterator_record:{}", m_next_method, m_iterator_record);
+    return ByteString::formatted("GetNextMethodFromIteratorRecord next_method:{} <- iterator_record:{}", m_next_method, m_iterator_record);
 }
 
 }
diff --git a/Userland/Libraries/LibJS/Bytecode/Op.h b/Userland/Libraries/LibJS/Bytecode/Op.h
index 5d8867b3ed4..effd1216053 100644
--- a/Userland/Libraries/LibJS/Bytecode/Op.h
+++ b/Userland/Libraries/LibJS/Bytecode/Op.h
@@ -39,7 +39,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register src() const { return m_src; }
 
@@ -56,7 +56,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Value value() const { return m_value; }
 
@@ -73,7 +73,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register dst() const { return m_dst; }
 
@@ -105,22 +105,22 @@ private:
     O(RightShift, right_shift)                \
     O(UnsignedRightShift, unsigned_right_shift)
 
-#define JS_DECLARE_COMMON_BINARY_OP(OpTitleCase, op_snake_case)                        \
-    class OpTitleCase final : public Instruction {                                     \
-    public:                                                                            \
-        explicit OpTitleCase(Register lhs_reg)                                         \
-            : Instruction(Type::OpTitleCase, sizeof(*this))                            \
-            , m_lhs_reg(lhs_reg)                                                       \
-        {                                                                              \
-        }                                                                              \
-                                                                                       \
-        ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;            \
-        DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const; \
-                                                                                       \
-        Register lhs() const { return m_lhs_reg; }                                     \
-                                                                                       \
-    private:                                                                           \
-        Register m_lhs_reg;                                                            \
+#define JS_DECLARE_COMMON_BINARY_OP(OpTitleCase, op_snake_case)             \
+    class OpTitleCase final : public Instruction {                          \
+    public:                                                                 \
+        explicit OpTitleCase(Register lhs_reg)                              \
+            : Instruction(Type::OpTitleCase, sizeof(*this))                 \
+            , m_lhs_reg(lhs_reg)                                            \
+        {                                                                   \
+        }                                                                   \
+                                                                            \
+        ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const; \
+        ByteString to_byte_string_impl(Bytecode::Executable const&) const;  \
+                                                                            \
+        Register lhs() const { return m_lhs_reg; }                          \
+                                                                            \
+    private:                                                                \
+        Register m_lhs_reg;                                                 \
     };
 
 JS_ENUMERATE_COMMON_BINARY_OPS(JS_DECLARE_COMMON_BINARY_OP)
@@ -133,16 +133,16 @@ JS_ENUMERATE_COMMON_BINARY_OPS(JS_DECLARE_COMMON_BINARY_OP)
     O(UnaryMinus, unary_minus)           \
     O(Typeof, typeof_)
 
-#define JS_DECLARE_COMMON_UNARY_OP(OpTitleCase, op_snake_case)                         \
-    class OpTitleCase final : public Instruction {                                     \
-    public:                                                                            \
-        OpTitleCase()                                                                  \
-            : Instruction(Type::OpTitleCase, sizeof(*this))                            \
-        {                                                                              \
-        }                                                                              \
-                                                                                       \
-        ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;            \
-        DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const; \
+#define JS_DECLARE_COMMON_UNARY_OP(OpTitleCase, op_snake_case)              \
+    class OpTitleCase final : public Instruction {                          \
+    public:                                                                 \
+        OpTitleCase()                                                       \
+            : Instruction(Type::OpTitleCase, sizeof(*this))                 \
+        {                                                                   \
+        }                                                                   \
+                                                                            \
+        ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const; \
+        ByteString to_byte_string_impl(Bytecode::Executable const&) const;  \
     };
 
 JS_ENUMERATE_COMMON_UNARY_OPS(JS_DECLARE_COMMON_UNARY_OP)
@@ -157,7 +157,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     StringTableIndex index() const { return m_string; }
 
@@ -173,7 +173,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class NewRegExp final : public Instruction {
@@ -187,7 +187,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     StringTableIndex source_index() const { return m_source_index; }
     StringTableIndex flags_index() const { return m_flags_index; }
@@ -202,22 +202,22 @@ private:
 #define JS_ENUMERATE_NEW_BUILTIN_ERROR_OPS(O) \
     O(TypeError)
 
-#define JS_DECLARE_NEW_BUILTIN_ERROR_OP(ErrorName)                                     \
-    class New##ErrorName final : public Instruction {                                  \
-    public:                                                                            \
-        explicit New##ErrorName(StringTableIndex error_string)                         \
-            : Instruction(Type::New##ErrorName, sizeof(*this))                         \
-            , m_error_string(error_string)                                             \
-        {                                                                              \
-        }                                                                              \
-                                                                                       \
-        ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;            \
-        DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const; \
-                                                                                       \
-        StringTableIndex error_string() const { return m_error_string; }               \
-                                                                                       \
-    private:                                                                           \
-        StringTableIndex m_error_string;                                               \
+#define JS_DECLARE_NEW_BUILTIN_ERROR_OP(ErrorName)                          \
+    class New##ErrorName final : public Instruction {                       \
+    public:                                                                 \
+        explicit New##ErrorName(StringTableIndex error_string)              \
+            : Instruction(Type::New##ErrorName, sizeof(*this))              \
+            , m_error_string(error_string)                                  \
+        {                                                                   \
+        }                                                                   \
+                                                                            \
+        ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const; \
+        ByteString to_byte_string_impl(Bytecode::Executable const&) const;  \
+                                                                            \
+        StringTableIndex error_string() const { return m_error_string; }    \
+                                                                            \
+    private:                                                                \
+        StringTableIndex m_error_string;                                    \
     };
 
 JS_ENUMERATE_NEW_BUILTIN_ERROR_OPS(JS_DECLARE_NEW_BUILTIN_ERROR_OP)
@@ -236,7 +236,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     size_t length_impl(size_t excluded_names_count) const
     {
@@ -262,7 +262,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Crypto::SignedBigInteger const& bigint() const { return m_bigint; }
 
@@ -288,7 +288,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     size_t length_impl(size_t element_count) const
     {
@@ -323,7 +323,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     ReadonlySpan<Value> values() const { return m_values.span(); }
 
@@ -341,7 +341,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register lhs() const { return m_lhs; }
     bool is_spread() const { return m_is_spread; }
@@ -361,7 +361,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register specifier() const { return m_specifier; }
     Register options() const { return m_options; }
@@ -379,7 +379,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class ConcatString final : public Instruction {
@@ -391,7 +391,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register lhs() const { return m_lhs; }
 
@@ -412,7 +412,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class EnterObjectEnvironment final : public Instruction {
@@ -423,7 +423,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class Catch final : public Instruction {
@@ -434,7 +434,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class CreateVariable final : public Instruction {
@@ -450,7 +450,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex identifier() const { return m_identifier; }
     EnvironmentMode mode() const { return m_mode; }
@@ -482,7 +482,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex identifier() const { return m_identifier; }
     EnvironmentMode mode() const { return m_mode; }
@@ -505,7 +505,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     size_t index() const { return m_index; }
 
@@ -525,7 +525,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex identifier() const { return m_identifier; }
     u32 cache_index() const { return m_cache_index; }
@@ -549,7 +549,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex identifier() const { return m_identifier; }
     u32 cache_index() const { return m_cache_index; }
@@ -569,7 +569,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex identifier() const { return m_identifier; }
     u32 cache_index() const { return m_cache_index; }
@@ -588,7 +588,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     size_t index() const { return m_index; }
 
@@ -605,7 +605,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex identifier() const { return m_identifier; }
 
@@ -623,7 +623,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex property() const { return m_property; }
     u32 cache_index() const { return m_cache_index; }
@@ -644,7 +644,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex property() const { return m_property; }
     Register this_value() const { return m_this_value; }
@@ -665,7 +665,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex property() const { return m_property; }
 
@@ -682,7 +682,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex property() const { return m_property; }
 
@@ -711,7 +711,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register base() const { return m_base; }
     IdentifierTableIndex property() const { return m_property; }
@@ -738,7 +738,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register base() const { return m_base; }
     Register this_value() const { return m_this_value; }
@@ -765,7 +765,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register base() const { return m_base; }
     IdentifierTableIndex property() const { return m_property; }
@@ -785,7 +785,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex property() const { return m_property; }
 
@@ -803,7 +803,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register this_value() const { return m_this_value; }
     IdentifierTableIndex property() const { return m_property; }
@@ -822,7 +822,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register base() const { return m_base; }
 
@@ -840,7 +840,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register base() const { return m_base; }
     Register this_value() const { return m_this_value; }
@@ -861,7 +861,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register base() const { return m_base; }
     Register property() const { return m_property; }
@@ -885,7 +885,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register base() const { return m_base; }
     Register property() const { return m_property; }
@@ -908,7 +908,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register base() const { return m_base; }
 
@@ -929,7 +929,7 @@ public:
     Register this_value() const { return m_this_value; }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
 private:
     Register m_base;
@@ -955,7 +955,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     auto& true_target() const { return m_true_target; }
     auto& false_target() const { return m_false_target; }
@@ -973,7 +973,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class JumpNullish final : public Jump {
@@ -984,7 +984,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class JumpUndefined final : public Jump {
@@ -995,7 +995,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 enum class CallType {
@@ -1029,7 +1029,7 @@ public:
     Optional<Builtin> const& builtin() const { return m_builtin; }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
 private:
     Register m_callee;
@@ -1058,7 +1058,7 @@ public:
     Optional<StringTableIndex> const& expression_string() const { return m_expression_string; }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
 private:
     Register m_callee;
@@ -1076,7 +1076,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     bool is_synthetic() const { return m_is_synthetic; }
 
@@ -1094,7 +1094,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     ClassExpression const& class_expression() const { return m_class_expression; }
     Optional<IdentifierTableIndex> const& lhs_name() const { return m_lhs_name; }
@@ -1115,7 +1115,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     FunctionExpression const& function_node() const { return m_function_node; }
     Optional<IdentifierTableIndex> const& lhs_name() const { return m_lhs_name; }
@@ -1136,7 +1136,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     ScopeNode const& scope_node() const { return m_scope_node; }
 
@@ -1154,7 +1154,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class Increment final : public Instruction {
@@ -1165,7 +1165,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class Decrement final : public Instruction {
@@ -1176,7 +1176,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class ToNumeric final : public Instruction {
@@ -1187,7 +1187,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class Throw final : public Instruction {
@@ -1200,7 +1200,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class ThrowIfNotObject final : public Instruction {
@@ -1211,7 +1211,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class ThrowIfNullish final : public Instruction {
@@ -1222,7 +1222,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class EnterUnwindContext final : public Instruction {
@@ -1236,7 +1236,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     auto& entry_point() const { return m_entry_point; }
 
@@ -1266,7 +1266,7 @@ public:
     Label target() const { return m_target; }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
 private:
     Label m_target;
@@ -1280,7 +1280,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class LeaveUnwindContext final : public Instruction {
@@ -1291,7 +1291,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class ContinuePendingUnwind final : public Instruction {
@@ -1305,7 +1305,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     auto& resume_target() const { return m_resume_target; }
 
@@ -1329,7 +1329,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     auto& continuation() const { return m_continuation_label; }
 
@@ -1348,7 +1348,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     auto& continuation() const { return m_continuation_label; }
 
@@ -1365,7 +1365,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IteratorHint hint() const { return m_hint; }
 
@@ -1383,7 +1383,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register object() const { return m_object; }
     Register iterator_record() const { return m_iterator_record; }
@@ -1403,7 +1403,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Register next_method() const { return m_next_method; }
     Register iterator_record() const { return m_iterator_record; }
@@ -1422,7 +1422,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex property() const { return m_property; }
 
@@ -1438,7 +1438,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class IteratorClose final : public Instruction {
@@ -1451,7 +1451,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Completion::Type completion_type() const { return m_completion_type; }
     Optional<Value> const& completion_value() const { return m_completion_value; }
@@ -1471,7 +1471,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     Completion::Type completion_type() const { return m_completion_type; }
     Optional<Value> const& completion_value() const { return m_completion_value; }
@@ -1489,7 +1489,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class ResolveThisBinding final : public Instruction {
@@ -1500,7 +1500,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class ResolveSuperBase final : public Instruction {
@@ -1511,7 +1511,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class GetNewTarget final : public Instruction {
@@ -1522,7 +1522,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class GetImportMeta final : public Instruction {
@@ -1533,7 +1533,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 };
 
 class TypeofVariable final : public Instruction {
@@ -1545,7 +1545,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     IdentifierTableIndex identifier() const { return m_identifier; }
 
@@ -1562,7 +1562,7 @@ public:
     }
 
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
-    DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
+    ByteString to_byte_string_impl(Bytecode::Executable const&) const;
 
     size_t index() const { return m_index; }
 
diff --git a/Userland/Libraries/LibJS/Bytecode/RegexTable.h b/Userland/Libraries/LibJS/Bytecode/RegexTable.h
index 6951d6f08b6..60fcf6b1561 100644
--- a/Userland/Libraries/LibJS/Bytecode/RegexTable.h
+++ b/Userland/Libraries/LibJS/Bytecode/RegexTable.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/DistinctNumeric.h>
 #include <AK/Vector.h>
 #include <LibRegex/RegexParser.h>
@@ -17,7 +17,7 @@ AK_TYPEDEF_DISTINCT_NUMERIC_GENERAL(size_t, RegexTableIndex, Comparison);
 
 struct ParsedRegex {
     regex::Parser::Result regex;
-    DeprecatedString pattern;
+    ByteString pattern;
     regex::RegexOptions<ECMAScriptFlags> flags;
 };
 
diff --git a/Userland/Libraries/LibJS/Bytecode/StringTable.cpp b/Userland/Libraries/LibJS/Bytecode/StringTable.cpp
index e42f41417dc..a989408ff86 100644
--- a/Userland/Libraries/LibJS/Bytecode/StringTable.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/StringTable.cpp
@@ -8,13 +8,13 @@
 
 namespace JS::Bytecode {
 
-StringTableIndex StringTable::insert(DeprecatedString string)
+StringTableIndex StringTable::insert(ByteString string)
 {
     m_strings.append(move(string));
     return m_strings.size() - 1;
 }
 
-DeprecatedString const& StringTable::get(StringTableIndex index) const
+ByteString const& StringTable::get(StringTableIndex index) const
 {
     return m_strings[index.value()];
 }
diff --git a/Userland/Libraries/LibJS/Bytecode/StringTable.h b/Userland/Libraries/LibJS/Bytecode/StringTable.h
index cf6981e9acd..8ed719052b5 100644
--- a/Userland/Libraries/LibJS/Bytecode/StringTable.h
+++ b/Userland/Libraries/LibJS/Bytecode/StringTable.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/DistinctNumeric.h>
 #include <AK/Vector.h>
 
@@ -21,13 +21,13 @@ class StringTable {
 public:
     StringTable() = default;
 
-    StringTableIndex insert(DeprecatedString);
-    DeprecatedString const& get(StringTableIndex) const;
+    StringTableIndex insert(ByteString);
+    ByteString const& get(StringTableIndex) const;
     void dump() const;
     bool is_empty() const { return m_strings.is_empty(); }
 
 private:
-    Vector<DeprecatedString> m_strings;
+    Vector<ByteString> m_strings;
 };
 
 }
diff --git a/Userland/Libraries/LibJS/Contrib/Test262/262Object.cpp b/Userland/Libraries/LibJS/Contrib/Test262/262Object.cpp
index eebff484b82..adfced67cc2 100644
--- a/Userland/Libraries/LibJS/Contrib/Test262/262Object.cpp
+++ b/Userland/Libraries/LibJS/Contrib/Test262/262Object.cpp
@@ -84,7 +84,7 @@ JS_DEFINE_NATIVE_FUNCTION($262Object::detach_array_buffer)
 
 JS_DEFINE_NATIVE_FUNCTION($262Object::eval_script)
 {
-    auto source_text = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto source_text = TRY(vm.argument(0).to_byte_string(vm));
 
     // 1. Let hostDefined be any host-defined values for the provided sourceText (obtained in an implementation dependent manner)
 
diff --git a/Userland/Libraries/LibJS/Contrib/Test262/GlobalObject.cpp b/Userland/Libraries/LibJS/Contrib/Test262/GlobalObject.cpp
index 843dd8eadac..4bb637c18dd 100644
--- a/Userland/Libraries/LibJS/Contrib/Test262/GlobalObject.cpp
+++ b/Userland/Libraries/LibJS/Contrib/Test262/GlobalObject.cpp
@@ -36,7 +36,7 @@ void GlobalObject::visit_edges(Cell::Visitor& visitor)
 
 JS_DEFINE_NATIVE_FUNCTION(GlobalObject::print)
 {
-    auto string = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto string = TRY(vm.argument(0).to_byte_string(vm));
     outln("{}", string);
     return js_undefined();
 }
diff --git a/Userland/Libraries/LibJS/CyclicModule.cpp b/Userland/Libraries/LibJS/CyclicModule.cpp
index fc1065bd326..d2bffac0da6 100644
--- a/Userland/Libraries/LibJS/CyclicModule.cpp
+++ b/Userland/Libraries/LibJS/CyclicModule.cpp
@@ -214,7 +214,7 @@ ThrowCompletionOr<u32> CyclicModule::inner_module_linking(VM& vm, Vector<Module*
     //    b. Return index.
     // Note: Step 1, 1.a and 1.b are handled in Module.cpp
 
-    dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] inner_module_linking[{}](vm, {}, {})", this, DeprecatedString::join(',', stack), index);
+    dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] inner_module_linking[{}](vm, {}, {})", this, ByteString::join(',', stack), index);
 
     // 2. If module.[[Status]] is linking, linked, evaluating-async, or evaluated, then
     if (m_status == ModuleStatus::Linking || m_status == ModuleStatus::Linked || m_status == ModuleStatus::EvaluatingAsync || m_status == ModuleStatus::Evaluated) {
@@ -418,7 +418,7 @@ ThrowCompletionOr<Promise*> CyclicModule::evaluate(VM& vm)
 // 16.2.1.5.2.1 InnerModuleEvaluation ( module, stack, index ), https://tc39.es/ecma262/#sec-innermoduleevaluation
 ThrowCompletionOr<u32> CyclicModule::inner_module_evaluation(VM& vm, Vector<Module*>& stack, u32 index)
 {
-    dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] inner_module_evaluation[{}](vm, {}, {})", this, DeprecatedString::join(", "sv, stack), index);
+    dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] inner_module_evaluation[{}](vm, {}, {})", this, ByteString::join(", "sv, stack), index);
     // Note: Step 1 is performed in Module.cpp
 
     // 2. If module.[[Status]] is evaluating-async or evaluated, then
diff --git a/Userland/Libraries/LibJS/Heap/Heap.cpp b/Userland/Libraries/LibJS/Heap/Heap.cpp
index 2b263ba473a..5fabb1c0b93 100644
--- a/Userland/Libraries/LibJS/Heap/Heap.cpp
+++ b/Userland/Libraries/LibJS/Heap/Heap.cpp
@@ -66,7 +66,7 @@ Heap::Heap(VM& vm)
 Heap::~Heap()
 {
     vm().string_cache().clear();
-    vm().deprecated_string_cache().clear();
+    vm().byte_string_cache().clear();
     collect_garbage(CollectionType::CollectEverything);
 }
 
@@ -198,7 +198,7 @@ public:
         for (auto& it : m_graph) {
             AK::JsonArray edges;
             for (auto const& value : it.value.edges) {
-                edges.must_append(DeprecatedString::formatted("{}", value));
+                edges.must_append(ByteString::formatted("{}", value));
             }
 
             auto node = AK::JsonObject();
@@ -207,7 +207,7 @@ public:
                 auto location = it.value.root_origin->location;
                 switch (type) {
                 case HeapRoot::Type::Handle:
-                    node.set("root"sv, DeprecatedString::formatted("Handle {} {}:{}", location->function_name(), location->filename(), location->line_number()));
+                    node.set("root"sv, ByteString::formatted("Handle {} {}:{}", location->function_name(), location->filename(), location->line_number()));
                     break;
                 case HeapRoot::Type::MarkedVector:
                     node.set("root"sv, "MarkedVector");
@@ -222,7 +222,7 @@ public:
                     node.set("root"sv, "VM");
                     break;
                 case HeapRoot::Type::SafeFunction:
-                    node.set("root"sv, DeprecatedString::formatted("SafeFunction {} {}:{}", location->function_name(), location->filename(), location->line_number()));
+                    node.set("root"sv, ByteString::formatted("SafeFunction {} {}:{}", location->function_name(), location->filename(), location->line_number()));
                     break;
                 default:
                     VERIFY_NOT_REACHED();
@@ -230,7 +230,7 @@ public:
             }
             node.set("class_name"sv, it.value.class_name);
             node.set("edges"sv, edges);
-            graph.set(DeprecatedString::number(it.key), node);
+            graph.set(ByteString::number(it.key), node);
         }
 
         return graph;
diff --git a/Userland/Libraries/LibJS/JIT/Compiler.cpp b/Userland/Libraries/LibJS/JIT/Compiler.cpp
index e8268cc2c2c..b77964526cf 100644
--- a/Userland/Libraries/LibJS/JIT/Compiler.cpp
+++ b/Userland/Libraries/LibJS/JIT/Compiler.cpp
@@ -1470,7 +1470,7 @@ void Compiler::compile_return(Bytecode::Op::Return const&)
     }
 }
 
-static Value cxx_new_string(VM& vm, DeprecatedString const& string)
+static Value cxx_new_string(VM& vm, ByteString const& string)
 {
     return PrimitiveString::create(vm, string);
 }
@@ -3428,7 +3428,7 @@ void Compiler::compile_has_private_id(Bytecode::Op::HasPrivateId const& op)
 }
 
 #    define COMPILE_NEW_BUILTIN_ERROR_OP(NewErrorName, new_error_name, ErrorName)                              \
-        static Value cxx_##new_error_name(VM& vm, DeprecatedString const& error_string)                        \
+        static Value cxx_##new_error_name(VM& vm, ByteString const& error_string)                              \
         {                                                                                                      \
             return ErrorName::create(*vm.current_realm(), error_string);                                       \
         }                                                                                                      \
@@ -3663,7 +3663,7 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable& bytecode_execut
             default:
                 if constexpr (LOG_JIT_FAILURE) {
                     dbgln("\033[31;1mJIT compilation failed\033[0m: {}", bytecode_executable.name);
-                    dbgln("Unsupported bytecode op: {}", op.to_deprecated_string(bytecode_executable));
+                    dbgln("Unsupported bytecode op: {}", op.to_byte_string(bytecode_executable));
                 }
                 return nullptr;
             }
diff --git a/Userland/Libraries/LibJS/JIT/NativeExecutable.cpp b/Userland/Libraries/LibJS/JIT/NativeExecutable.cpp
index ec3706c780c..ff13a5b10ba 100644
--- a/Userland/Libraries/LibJS/JIT/NativeExecutable.cpp
+++ b/Userland/Libraries/LibJS/JIT/NativeExecutable.cpp
@@ -67,7 +67,7 @@ public:
 
     virtual ~JITSymbolProvider() override = default;
 
-    virtual DeprecatedString symbolicate(FlatPtr address, u32* offset = nullptr) const override
+    virtual ByteString symbolicate(FlatPtr address, u32* offset = nullptr) const override
     {
         auto base = bit_cast<FlatPtr>(m_executable.code_bytes().data());
         auto native_offset = static_cast<u32>(address - base);
@@ -83,9 +83,9 @@ public:
             return BytecodeMapping::EXECUTABLE_LABELS[entry.bytecode_offset];
 
         if (entry.bytecode_offset == 0)
-            return DeprecatedString::formatted("Block {}", entry.block_index + 1);
+            return ByteString::formatted("Block {}", entry.block_index + 1);
 
-        return DeprecatedString::formatted("{}:{:x}", entry.block_index + 1, entry.bytecode_offset);
+        return ByteString::formatted("{}:{:x}", entry.block_index + 1, entry.bytecode_offset);
     }
 
 private:
@@ -127,7 +127,7 @@ void NativeExecutable::dump_disassembly([[maybe_unused]] Bytecode::Executable co
                 if (block.size() != 0) {
                     VERIFY(mapping->bytecode_offset < block.size());
                     auto const& instruction = *reinterpret_cast<Bytecode::Instruction const*>(block.data() + mapping->bytecode_offset);
-                    dbgln("{}:{:x} {}:", mapping->block_index + 1, mapping->bytecode_offset, instruction.to_deprecated_string(executable));
+                    dbgln("{}:{:x} {}:", mapping->block_index + 1, mapping->bytecode_offset, instruction.to_byte_string(executable));
                 }
             }
         }
@@ -146,7 +146,7 @@ void NativeExecutable::dump_disassembly([[maybe_unused]] Bytecode::Executable co
                 builder.append("   "sv);
         }
         builder.append(" "sv);
-        builder.append(insn.value().to_deprecated_string(virtual_offset, &symbol_provider));
+        builder.append(insn.value().to_byte_string(virtual_offset, &symbol_provider));
         dbgln("{}", builder.string_view());
 
         for (size_t bytes_printed = 7; bytes_printed < length; bytes_printed += 7) {
diff --git a/Userland/Libraries/LibJS/Lexer.cpp b/Userland/Libraries/LibJS/Lexer.cpp
index ec4bf8359f2..98d5efce98d 100644
--- a/Userland/Libraries/LibJS/Lexer.cpp
+++ b/Userland/Libraries/LibJS/Lexer.cpp
@@ -17,8 +17,8 @@
 namespace JS {
 
 HashMap<DeprecatedFlyString, TokenType> Lexer::s_keywords;
-HashMap<DeprecatedString, TokenType> Lexer::s_three_char_tokens;
-HashMap<DeprecatedString, TokenType> Lexer::s_two_char_tokens;
+HashMap<ByteString, TokenType> Lexer::s_three_char_tokens;
+HashMap<ByteString, TokenType> Lexer::s_two_char_tokens;
 HashMap<char, TokenType> Lexer::s_single_char_tokens;
 
 Lexer::Lexer(StringView source, StringView filename, size_t line_number, size_t line_column)
@@ -159,7 +159,7 @@ void Lexer::consume()
 
     if (is_line_terminator()) {
         if constexpr (LEXER_DEBUG) {
-            DeprecatedString type;
+            ByteString type;
             if (m_current_char == '\n')
                 type = "LINE FEED";
             else if (m_current_char == '\r')
@@ -567,7 +567,7 @@ Token Lexer::next()
     // This is being used to communicate info about invalid tokens to the parser, which then
     // can turn that into more specific error messages - instead of us having to make up a
     // bunch of Invalid* tokens (bad numeric literals, unterminated comments etc.)
-    DeprecatedString token_message;
+    ByteString token_message;
 
     Optional<DeprecatedFlyString> identifier;
     size_t identifier_length = 0;
@@ -844,7 +844,7 @@ Token Lexer::next()
     } else {
         m_current_token = Token(
             token_type,
-            String::from_deprecated_string(token_message).release_value_but_fixme_should_propagate_errors(),
+            String::from_byte_string(token_message).release_value_but_fixme_should_propagate_errors(),
             m_source.substring_view(trivia_start - 1, value_start - trivia_start),
             m_source.substring_view(value_start - 1, m_position - value_start),
             m_filename,
diff --git a/Userland/Libraries/LibJS/Lexer.h b/Userland/Libraries/LibJS/Lexer.h
index ebe0df73d71..704801a405c 100644
--- a/Userland/Libraries/LibJS/Lexer.h
+++ b/Userland/Libraries/LibJS/Lexer.h
@@ -8,7 +8,7 @@
 
 #include "Token.h"
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/String.h>
 #include <AK/StringView.h>
@@ -21,7 +21,7 @@ public:
 
     Token next();
 
-    DeprecatedString const& source() const { return m_source; }
+    ByteString const& source() const { return m_source; }
     String const& filename() const { return m_filename; }
 
     void disallow_html_comments() { m_allow_html_comments = false; }
@@ -58,7 +58,7 @@ private:
 
     TokenType consume_regex_literal();
 
-    DeprecatedString m_source;
+    ByteString m_source;
     size_t m_position { 0 };
     Token m_current_token;
     char m_current_char { 0 };
@@ -81,8 +81,8 @@ private:
     Optional<size_t> m_hit_invalid_unicode;
 
     static HashMap<DeprecatedFlyString, TokenType> s_keywords;
-    static HashMap<DeprecatedString, TokenType> s_three_char_tokens;
-    static HashMap<DeprecatedString, TokenType> s_two_char_tokens;
+    static HashMap<ByteString, TokenType> s_three_char_tokens;
+    static HashMap<ByteString, TokenType> s_two_char_tokens;
     static HashMap<char, TokenType> s_single_char_tokens;
 
     struct ParsedIdentifiers : public RefCounted<ParsedIdentifiers> {
diff --git a/Userland/Libraries/LibJS/Module.cpp b/Userland/Libraries/LibJS/Module.cpp
index 3277889b183..a729612bfe8 100644
--- a/Userland/Libraries/LibJS/Module.cpp
+++ b/Userland/Libraries/LibJS/Module.cpp
@@ -17,7 +17,7 @@ namespace JS {
 
 JS_DEFINE_ALLOCATOR(Module);
 
-Module::Module(Realm& realm, DeprecatedString filename, Script::HostDefined* host_defined)
+Module::Module(Realm& realm, ByteString filename, Script::HostDefined* host_defined)
     : m_realm(realm)
     , m_host_defined(host_defined)
     , m_filename(move(filename))
diff --git a/Userland/Libraries/LibJS/Module.h b/Userland/Libraries/LibJS/Module.h
index 3813c7fd620..a32f98db91f 100644
--- a/Userland/Libraries/LibJS/Module.h
+++ b/Userland/Libraries/LibJS/Module.h
@@ -117,7 +117,7 @@ public:
     virtual PromiseCapability& load_requested_modules(GCPtr<GraphLoadingState::HostDefined>) = 0;
 
 protected:
-    Module(Realm&, DeprecatedString filename, Script::HostDefined* host_defined = nullptr);
+    Module(Realm&, ByteString filename, Script::HostDefined* host_defined = nullptr);
 
     virtual void visit_edges(Cell::Visitor&) override;
 
@@ -140,7 +140,7 @@ private:
     Script::HostDefined* m_host_defined { nullptr }; // [[HostDefined]]
 
     // Needed for potential lookups of modules.
-    DeprecatedString m_filename;
+    ByteString m_filename;
 };
 
 class CyclicModule;
diff --git a/Userland/Libraries/LibJS/Parser.cpp b/Userland/Libraries/LibJS/Parser.cpp
index 8a38a1815ef..8e6ec8725a9 100644
--- a/Userland/Libraries/LibJS/Parser.cpp
+++ b/Userland/Libraries/LibJS/Parser.cpp
@@ -438,7 +438,7 @@ public:
 private:
     void throw_identifier_declared(DeprecatedFlyString const& name, NonnullRefPtr<Declaration const> const& declaration)
     {
-        m_parser.syntax_error(DeprecatedString::formatted("Identifier '{}' already declared", name), declaration->source_range().start);
+        m_parser.syntax_error(ByteString::formatted("Identifier '{}' already declared", name), declaration->source_range().start);
     }
 
     Parser& m_parser;
@@ -612,7 +612,7 @@ Parser::ParserState::ParserState(Lexer l, Program::Type program_type)
 }
 
 Parser::Parser(Lexer lexer, Program::Type program_type, Optional<EvalInitialState> initial_state_for_eval)
-    : m_source_code(SourceCode::create(lexer.filename(), String::from_deprecated_string(lexer.source()).release_value_but_fixme_should_propagate_errors()))
+    : m_source_code(SourceCode::create(lexer.filename(), String::from_byte_string(lexer.source()).release_value_but_fixme_should_propagate_errors()))
     , m_state(move(lexer), program_type)
     , m_program_type(program_type)
 {
@@ -790,7 +790,7 @@ void Parser::parse_module(Program& program)
             }
 
             if (!found)
-                syntax_error(DeprecatedString::formatted("'{}' in export is not declared", exported_name), export_statement->source_range().start);
+                syntax_error(ByteString::formatted("'{}' in export is not declared", exported_name), export_statement->source_range().start);
         }
     }
 }
@@ -883,9 +883,9 @@ NonnullRefPtr<Statement const> Parser::parse_statement(AllowLabelledFunction all
                 if (lookahead_token.type() == TokenType::Function && !lookahead_token.trivia_contains_line_terminator())
                     syntax_error("Async function declaration not allowed in single-statement context");
             } else if (match(TokenType::Function) || match(TokenType::Class)) {
-                syntax_error(DeprecatedString::formatted("{} declaration not allowed in single-statement context", m_state.current_token.name()));
+                syntax_error(ByteString::formatted("{} declaration not allowed in single-statement context", m_state.current_token.name()));
             } else if (match(TokenType::Let) && next_token().type() == TokenType::BracketOpen) {
-                syntax_error(DeprecatedString::formatted("let followed by [ is not allowed in single-statement context"));
+                syntax_error(ByteString::formatted("let followed by [ is not allowed in single-statement context"));
             }
 
             auto expr = parse_expression(0);
@@ -1078,7 +1078,7 @@ RefPtr<FunctionExpression const> Parser::try_parse_arrow_function_expression(boo
 
     auto function_start_offset = rule_start.position().offset;
     auto function_end_offset = position().offset - m_state.current_token.trivia().length();
-    auto source_text = DeprecatedString { m_state.lexer.source().substring_view(function_start_offset, function_end_offset - function_start_offset) };
+    auto source_text = ByteString { m_state.lexer.source().substring_view(function_start_offset, function_end_offset - function_start_offset) };
     return create_ast_node<FunctionExpression>(
         { m_source_code, rule_start.position(), position() }, nullptr, move(source_text),
         move(body), move(parameters), function_length, function_kind, body->in_strict_mode(),
@@ -1134,7 +1134,7 @@ RefPtr<LabelledStatement const> Parser::try_parse_labelled_statement(AllowLabell
     }
 
     if (m_state.labels_in_scope.contains(identifier))
-        syntax_error(DeprecatedString::formatted("Label '{}' has already been declared", identifier));
+        syntax_error(ByteString::formatted("Label '{}' has already been declared", identifier));
 
     RefPtr<Statement const> labelled_item;
 
@@ -1401,7 +1401,7 @@ NonnullRefPtr<ClassExpression const> Parser::parse_class_expression(bool expect_
 
                             if (element->class_element_kind() != ClassElement::ElementKind::Method
                                 || element->is_static() != is_static) {
-                                syntax_error(DeprecatedString::formatted("Duplicate private field or method named '{}'", name));
+                                syntax_error(ByteString::formatted("Duplicate private field or method named '{}'", name));
                                 break;
                             }
 
@@ -1409,14 +1409,14 @@ NonnullRefPtr<ClassExpression const> Parser::parse_class_expression(bool expect_
                             auto& class_method_element = static_cast<ClassMethod const&>(*element);
 
                             if (class_method_element.kind() == ClassMethod::Kind::Method || class_method_element.kind() == method_kind) {
-                                syntax_error(DeprecatedString::formatted("Duplicate private field or method named '{}'", name));
+                                syntax_error(ByteString::formatted("Duplicate private field or method named '{}'", name));
                                 break;
                             }
                         }
 
                         found_private_names.set(name);
                     } else if (found_private_names.set(name) != AK::HashSetResult::InsertedNewEntry) {
-                        syntax_error(DeprecatedString::formatted("Duplicate private field or method named '{}'", name));
+                        syntax_error(ByteString::formatted("Duplicate private field or method named '{}'", name));
                     }
 
                     property_key = create_ast_node<PrivateIdentifier>({ m_source_code, rule_start.position(), position() }, name);
@@ -1590,12 +1590,12 @@ NonnullRefPtr<ClassExpression const> Parser::parse_class_expression(bool expect_
         if (outer_referenced_private_names)
             outer_referenced_private_names->set(private_name);
         else // FIXME: Make these error appear in the appropriate places.
-            syntax_error(DeprecatedString::formatted("Reference to undeclared private field or method '{}'", private_name));
+            syntax_error(ByteString::formatted("Reference to undeclared private field or method '{}'", private_name));
     }
 
     auto function_start_offset = rule_start.position().offset;
     auto function_end_offset = position().offset - m_state.current_token.trivia().length();
-    auto source_text = DeprecatedString { m_state.lexer.source().substring_view(function_start_offset, function_end_offset - function_start_offset) };
+    auto source_text = ByteString { m_state.lexer.source().substring_view(function_start_offset, function_end_offset - function_start_offset) };
 
     return create_ast_node<ClassExpression>({ m_source_code, rule_start.position(), position() }, move(class_name), move(source_text), move(constructor), move(super_class), move(elements));
 }
@@ -1661,7 +1661,7 @@ Parser::PrimaryExpressionParseResult Parser::parse_primary_expression()
         auto string = m_state.current_token.value();
         // This could be 'eval' or 'arguments' and thus needs a custom check (`eval[1] = true`)
         if (m_state.strict_mode && (string == "let" || is_strict_reserved_word(string)))
-            syntax_error(DeprecatedString::formatted("Identifier must not be a reserved word in strict mode ('{}')", string));
+            syntax_error(ByteString::formatted("Identifier must not be a reserved word in strict mode ('{}')", string));
         return { parse_identifier() };
     }
     case TokenType::NumericLiteral:
@@ -1740,7 +1740,7 @@ Parser::PrimaryExpressionParseResult Parser::parse_primary_expression()
         return { parse_await_expression() };
     case TokenType::PrivateIdentifier:
         if (!is_private_identifier_valid())
-            syntax_error(DeprecatedString::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value()));
+            syntax_error(ByteString::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value()));
         if (next_token().type() != TokenType::In)
             syntax_error("Cannot have a private identifier in expression if not followed by 'in'");
         return { create_ast_node<PrivateIdentifier>({ m_source_code, rule_start.position(), position() }, consume().value()) };
@@ -1761,7 +1761,7 @@ NonnullRefPtr<RegExpLiteral const> Parser::parse_regexp_literal()
     // Remove leading and trailing slash.
     pattern = pattern.substring_view(1, pattern.length() - 2);
 
-    auto flags = DeprecatedString::empty();
+    auto flags = ByteString::empty();
     auto parsed_flags = RegExpObject::default_flags;
 
     if (match(TokenType::RegexFlags)) {
@@ -1775,21 +1775,21 @@ NonnullRefPtr<RegExpLiteral const> Parser::parse_regexp_literal()
             parsed_flags = parsed_flags_or_error.release_value();
     }
 
-    DeprecatedString parsed_pattern;
+    ByteString parsed_pattern;
     auto parsed_pattern_result = parse_regex_pattern(pattern, parsed_flags.has_flag_set(ECMAScriptFlags::Unicode), parsed_flags.has_flag_set(ECMAScriptFlags::UnicodeSets));
     if (parsed_pattern_result.is_error()) {
         syntax_error(parsed_pattern_result.release_error().error, rule_start.position());
-        parsed_pattern = DeprecatedString::empty();
+        parsed_pattern = ByteString::empty();
     } else {
         parsed_pattern = parsed_pattern_result.release_value();
     }
     auto parsed_regex = Regex<ECMA262>::parse_pattern(parsed_pattern, parsed_flags);
 
     if (parsed_regex.error != regex::Error::NoError)
-        syntax_error(DeprecatedString::formatted("RegExp compile error: {}", Regex<ECMA262>(parsed_regex, parsed_pattern, parsed_flags).error_string()), rule_start.position());
+        syntax_error(ByteString::formatted("RegExp compile error: {}", Regex<ECMA262>(parsed_regex, parsed_pattern, parsed_flags).error_string()), rule_start.position());
 
     SourceRange range { m_source_code, rule_start.position(), position() };
-    return create_ast_node<RegExpLiteral>(move(range), move(parsed_regex), move(parsed_pattern), move(parsed_flags), pattern.to_deprecated_string(), move(flags));
+    return create_ast_node<RegExpLiteral>(move(range), move(parsed_regex), move(parsed_pattern), move(parsed_flags), pattern.to_byte_string(), move(flags));
 }
 
 static bool is_simple_assignment_target(Expression const& expression, bool allow_web_reality_call_expression = true)
@@ -1815,7 +1815,7 @@ NonnullRefPtr<Expression const> Parser::parse_unary_prefixed_expression()
         auto rhs_start = position();
         auto rhs = parse_expression(precedence, associativity);
         if (!is_simple_assignment_target(*rhs))
-            syntax_error(DeprecatedString::formatted("Right-hand side of prefix increment operator must be identifier or member expression, got {}", rhs->class_name()), rhs_start);
+            syntax_error(ByteString::formatted("Right-hand side of prefix increment operator must be identifier or member expression, got {}", rhs->class_name()), rhs_start);
 
         if (m_state.strict_mode && is<Identifier>(*rhs)) {
             auto& identifier = static_cast<Identifier const&>(*rhs);
@@ -1830,7 +1830,7 @@ NonnullRefPtr<Expression const> Parser::parse_unary_prefixed_expression()
         auto rhs_start = position();
         auto rhs = parse_expression(precedence, associativity);
         if (!is_simple_assignment_target(*rhs))
-            syntax_error(DeprecatedString::formatted("Right-hand side of prefix decrement operator must be identifier or member expression, got {}", rhs->class_name()), rhs_start);
+            syntax_error(ByteString::formatted("Right-hand side of prefix decrement operator must be identifier or member expression, got {}", rhs->class_name()), rhs_start);
 
         if (m_state.strict_mode && is<Identifier>(*rhs)) {
             auto& identifier = static_cast<Identifier const&>(*rhs);
@@ -2034,7 +2034,7 @@ NonnullRefPtr<ObjectExpression const> Parser::parse_object_expression()
             if (m_state.strict_mode && is<StringLiteral>(*property_key)) {
                 auto& string_literal = static_cast<StringLiteral const&>(*property_key);
                 if (is_strict_reserved_word(string_literal.value()))
-                    syntax_error(DeprecatedString::formatted("'{}' is a reserved keyword", string_literal.value()));
+                    syntax_error(ByteString::formatted("'{}' is a reserved keyword", string_literal.value()));
             }
 
             properties.append(create_ast_node<ObjectProperty>({ m_source_code, rule_start.position(), position() }, *property_key, *property_value, property_type, false));
@@ -2098,7 +2098,7 @@ NonnullRefPtr<StringLiteral const> Parser::parse_string_literal(Token const& tok
     auto string = token.string_value(status);
     // NOTE: Tagged templates should not fail on invalid strings as their raw contents can still be accessed.
     if (status != Token::StringValueStatus::Ok) {
-        DeprecatedString message;
+        ByteString message;
         if (status == Token::StringValueStatus::LegacyOctalEscapeSequence) {
             m_state.string_legacy_octal_escape_sequence_in_scope = true;
             // It is a Syntax Error if the [Tagged] parameter was not set and Template{Head, Middle, Tail} Contains NotEscapeSequence.
@@ -2108,7 +2108,7 @@ NonnullRefPtr<StringLiteral const> Parser::parse_string_literal(Token const& tok
                 message = "Octal escape sequence in string literal not allowed in strict mode";
         } else if (status == Token::StringValueStatus::MalformedHexEscape || status == Token::StringValueStatus::MalformedUnicodeEscape) {
             auto type = status == Token::StringValueStatus::MalformedUnicodeEscape ? "unicode" : "hexadecimal";
-            message = DeprecatedString::formatted("Malformed {} escape sequence", type);
+            message = ByteString::formatted("Malformed {} escape sequence", type);
         } else if (status == Token::StringValueStatus::UnicodeEscapeOverflow) {
             message = "Unicode code_point must not be greater than 0x10ffff in escape sequence";
         } else {
@@ -2373,9 +2373,9 @@ Parser::ExpressionResult Parser::parse_secondary_expression(NonnullRefPtr<Expres
         consume();
         if (match(TokenType::PrivateIdentifier)) {
             if (!is_private_identifier_valid())
-                syntax_error(DeprecatedString::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value()));
+                syntax_error(ByteString::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value()));
             else if (is<SuperExpression>(*lhs))
-                syntax_error(DeprecatedString::formatted("Cannot access private field or method '{}' on super", m_state.current_token.value()));
+                syntax_error(ByteString::formatted("Cannot access private field or method '{}' on super", m_state.current_token.value()));
 
             return create_ast_node<MemberExpression>({ m_source_code, rule_start.position(), position() }, move(lhs), create_ast_node<PrivateIdentifier>({ m_source_code, rule_start.position(), position() }, consume().value()));
         } else if (!match_identifier_name()) {
@@ -2391,7 +2391,7 @@ Parser::ExpressionResult Parser::parse_secondary_expression(NonnullRefPtr<Expres
     }
     case TokenType::PlusPlus:
         if (!is_simple_assignment_target(*lhs))
-            syntax_error(DeprecatedString::formatted("Left-hand side of postfix increment operator must be identifier or member expression, got {}", lhs->class_name()));
+            syntax_error(ByteString::formatted("Left-hand side of postfix increment operator must be identifier or member expression, got {}", lhs->class_name()));
 
         if (m_state.strict_mode && is<Identifier>(*lhs)) {
             auto& identifier = static_cast<Identifier const&>(*lhs);
@@ -2403,7 +2403,7 @@ Parser::ExpressionResult Parser::parse_secondary_expression(NonnullRefPtr<Expres
         return create_ast_node<UpdateExpression>({ m_source_code, rule_start.position(), position() }, UpdateOp::Increment, move(lhs));
     case TokenType::MinusMinus:
         if (!is_simple_assignment_target(*lhs))
-            syntax_error(DeprecatedString::formatted("Left-hand side of postfix increment operator must be identifier or member expression, got {}", lhs->class_name()));
+            syntax_error(ByteString::formatted("Left-hand side of postfix increment operator must be identifier or member expression, got {}", lhs->class_name()));
 
         if (m_state.strict_mode && is<Identifier>(*lhs)) {
             auto& identifier = static_cast<Identifier const&>(*lhs);
@@ -2760,7 +2760,7 @@ NonnullRefPtr<FunctionBody const> Parser::parse_function_body(Vector<FunctionPar
 
                     for (auto& previous_name : parameter_names) {
                         if (previous_name == parameter_name) {
-                            syntax_error(DeprecatedString::formatted("Duplicate parameter '{}' not allowed in strict mode", parameter_name));
+                            syntax_error(ByteString::formatted("Duplicate parameter '{}' not allowed in strict mode", parameter_name));
                         }
                     }
 
@@ -2779,7 +2779,7 @@ NonnullRefPtr<FunctionBody const> Parser::parse_function_body(Vector<FunctionPar
 
                         for (auto& previous_name : parameter_names) {
                             if (previous_name == bound_name) {
-                                syntax_error(DeprecatedString::formatted("Duplicate parameter '{}' not allowed in strict mode", bound_name));
+                                syntax_error(ByteString::formatted("Duplicate parameter '{}' not allowed in strict mode", bound_name));
                                 break;
                             }
                         }
@@ -2864,7 +2864,7 @@ NonnullRefPtr<FunctionNodeType> Parser::parse_function_node(u16 parse_options, O
             check_identifier_name_for_assignment_validity(name->string());
 
             if (function_kind == FunctionKind::AsyncGenerator && (name->string() == "await"sv || name->string() == "yield"sv))
-                syntax_error(DeprecatedString::formatted("async generator function is not allowed to be called '{}'", name->string()));
+                syntax_error(ByteString::formatted("async generator function is not allowed to be called '{}'", name->string()));
 
             if (m_state.in_class_static_init_block && name->string() == "await"sv)
                 syntax_error("'await' is a reserved word");
@@ -2910,7 +2910,7 @@ NonnullRefPtr<FunctionNodeType> Parser::parse_function_node(u16 parse_options, O
 
     auto function_start_offset = rule_start.position().offset;
     auto function_end_offset = position().offset - m_state.current_token.trivia().length();
-    auto source_text = DeprecatedString { m_state.lexer.source().substring_view(function_start_offset, function_end_offset - function_start_offset) };
+    auto source_text = ByteString { m_state.lexer.source().substring_view(function_start_offset, function_end_offset - function_start_offset) };
     return create_ast_node<FunctionNodeType>(
         { m_source_code, rule_start.position(), position() },
         name, move(source_text), move(body), move(parameters), function_length,
@@ -2955,15 +2955,15 @@ Vector<FunctionParameter> Parser::parse_formal_parameters(int& function_length,
             if (!has_same_name)
                 continue;
 
-            DeprecatedString message;
+            ByteString message;
             if (parse_options & FunctionNodeParseOptions::IsArrowFunction)
-                message = DeprecatedString::formatted("Duplicate parameter '{}' not allowed in arrow function", parameter_name);
+                message = ByteString::formatted("Duplicate parameter '{}' not allowed in arrow function", parameter_name);
             else if (m_state.strict_mode)
-                message = DeprecatedString::formatted("Duplicate parameter '{}' not allowed in strict mode", parameter_name);
+                message = ByteString::formatted("Duplicate parameter '{}' not allowed in strict mode", parameter_name);
             else if (has_default_parameter || match(TokenType::Equals))
-                message = DeprecatedString::formatted("Duplicate parameter '{}' not allowed in function with default parameter", parameter_name);
+                message = ByteString::formatted("Duplicate parameter '{}' not allowed in function with default parameter", parameter_name);
             else if (has_rest_parameter)
-                message = DeprecatedString::formatted("Duplicate parameter '{}' not allowed in function with rest parameter", parameter_name);
+                message = ByteString::formatted("Duplicate parameter '{}' not allowed in function with rest parameter", parameter_name);
             if (!message.is_empty())
                 syntax_error(message, Position { token.line_number(), token.line_column() });
             break;
@@ -3406,7 +3406,7 @@ NonnullRefPtr<BreakStatement const> Parser::parse_break_statement()
 
             auto label = m_state.labels_in_scope.find(target_label);
             if (label == m_state.labels_in_scope.end())
-                syntax_error(DeprecatedString::formatted("Label '{}' not found", target_label));
+                syntax_error(ByteString::formatted("Label '{}' not found", target_label));
         }
         consume_or_insert_semicolon();
     }
@@ -3435,7 +3435,7 @@ NonnullRefPtr<ContinueStatement const> Parser::parse_continue_statement()
 
         auto label = m_state.labels_in_scope.find(target_label);
         if (label == m_state.labels_in_scope.end())
-            syntax_error(DeprecatedString::formatted("Label '{}' not found or invalid", target_label));
+            syntax_error(ByteString::formatted("Label '{}' not found or invalid", target_label));
         else
             label->value = label_position;
     }
@@ -3471,7 +3471,7 @@ NonnullRefPtr<OptionalChain const> Parser::parse_optional_chain(NonnullRefPtr<Ex
                 break;
             case TokenType::PrivateIdentifier: {
                 if (!is_private_identifier_valid())
-                    syntax_error(DeprecatedString::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value()));
+                    syntax_error(ByteString::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value()));
 
                 auto start = position();
                 auto private_identifier = consume();
@@ -3507,7 +3507,7 @@ NonnullRefPtr<OptionalChain const> Parser::parse_optional_chain(NonnullRefPtr<Ex
             consume();
             if (match(TokenType::PrivateIdentifier)) {
                 if (!is_private_identifier_valid())
-                    syntax_error(DeprecatedString::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value()));
+                    syntax_error(ByteString::formatted("Reference to undeclared private field or method '{}'", m_state.current_token.value()));
 
                 auto start = position();
                 auto private_identifier = consume();
@@ -3728,7 +3728,7 @@ NonnullRefPtr<CatchClause const> Parser::parse_catch_clause()
     // NOTE: Nothing in the callback throws an exception.
     MUST(body->for_each_lexically_declared_identifier([&](auto const& identifier) {
         if (bound_names.contains(identifier.string()))
-            syntax_error(DeprecatedString::formatted("Identifier '{}' already declared as catch parameter", identifier.string()));
+            syntax_error(ByteString::formatted("Identifier '{}' already declared as catch parameter", identifier.string()));
     }));
 
     if (pattern_parameter) {
@@ -3951,7 +3951,7 @@ NonnullRefPtr<Statement const> Parser::parse_for_in_of_statement(NonnullRefPtr<A
             }
         }
         if (!valid)
-            syntax_error(DeprecatedString::formatted("Invalid left-hand side in for-loop ('{}')", lhs->class_name()));
+            syntax_error(ByteString::formatted("Invalid left-hand side in for-loop ('{}')", lhs->class_name()));
     }
     auto in_or_of = consume();
     auto is_in = in_or_of.type() == TokenType::In;
@@ -4341,7 +4341,7 @@ Token Parser::consume_identifier_reference()
     if (match(TokenType::EscapedKeyword)) {
         auto name = m_state.current_token.value();
         if (m_state.strict_mode && (name == "let"sv || name == "yield"sv))
-            syntax_error(DeprecatedString::formatted("'{}' is not allowed as an identifier in strict mode", name));
+            syntax_error(ByteString::formatted("'{}' is not allowed as an identifier in strict mode", name));
         if (m_program_type == Program::Type::Module && name == "await"sv)
             syntax_error("'await' is not allowed as an identifier in module");
 
@@ -4382,7 +4382,7 @@ Token Parser::consume(TokenType expected_type)
     auto token = expected_type == TokenType::Identifier ? consume_and_allow_division() : consume();
     if (expected_type == TokenType::Identifier) {
         if (m_state.strict_mode && is_strict_reserved_word(token.value()))
-            syntax_error(DeprecatedString::formatted("Identifier must not be a reserved word in strict mode ('{}')", token.value()));
+            syntax_error(ByteString::formatted("Identifier must not be a reserved word in strict mode ('{}')", token.value()));
     }
     return token;
 }
@@ -4403,9 +4403,9 @@ Token Parser::consume_and_validate_numeric_literal()
 
 void Parser::expected(char const* what)
 {
-    auto message = m_state.current_token.message().to_deprecated_string();
+    auto message = m_state.current_token.message().to_byte_string();
     if (message.is_empty())
-        message = DeprecatedString::formatted("Unexpected token {}. Expected {}", m_state.current_token.name(), what);
+        message = ByteString::formatted("Unexpected token {}. Expected {}", m_state.current_token.name(), what);
     syntax_error(message);
 }
 
@@ -4432,7 +4432,7 @@ void Parser::set_try_parse_arrow_function_expression_failed_at_position(Position
     m_token_memoizations.set(position, { failed });
 }
 
-void Parser::syntax_error(DeprecatedString const& message, Optional<Position> position)
+void Parser::syntax_error(ByteString const& message, Optional<Position> position)
 {
     if (!position.has_value())
         position = this->position();
@@ -4464,7 +4464,7 @@ void Parser::check_identifier_name_for_assignment_validity(DeprecatedFlyString c
         if (name.is_one_of("arguments"sv, "eval"sv))
             syntax_error("Binding pattern target may not be called 'arguments' or 'eval' in strict mode");
         else if (is_strict_reserved_word(name))
-            syntax_error(DeprecatedString::formatted("Binding pattern target may not be called '{}' in strict mode", name));
+            syntax_error(ByteString::formatted("Binding pattern target may not be called '{}' in strict mode", name));
     }
 }
 
@@ -4517,9 +4517,9 @@ ModuleRequest Parser::parse_module_request()
     consume(TokenType::CurlyOpen);
 
     while (!done() && !match(TokenType::CurlyClose)) {
-        DeprecatedString key;
+        ByteString key;
         if (match(TokenType::StringLiteral)) {
-            key = parse_string_literal(m_state.current_token)->value().to_deprecated_string();
+            key = parse_string_literal(m_state.current_token)->value().to_byte_string();
             consume();
         } else if (match_identifier_name()) {
             key = consume().value();
@@ -4533,9 +4533,9 @@ ModuleRequest Parser::parse_module_request()
         if (match(TokenType::StringLiteral)) {
             for (auto& entries : request.attributes) {
                 if (entries.key == key)
-                    syntax_error(DeprecatedString::formatted("Duplicate attribute clauses with name: {}", key));
+                    syntax_error(ByteString::formatted("Duplicate attribute clauses with name: {}", key));
             }
-            request.add_attribute(move(key), parse_string_literal(m_state.current_token)->value().to_deprecated_string());
+            request.add_attribute(move(key), parse_string_literal(m_state.current_token)->value().to_byte_string());
         }
         consume(TokenType::StringLiteral);
 
@@ -4617,7 +4617,7 @@ NonnullRefPtr<ImportStatement const> Parser::parse_import_statement(Program& pro
         consume(TokenType::Asterisk);
 
         if (!match_as())
-            syntax_error(DeprecatedString::formatted("Unexpected token: {}", m_state.current_token.name()));
+            syntax_error(ByteString::formatted("Unexpected token: {}", m_state.current_token.name()));
 
         consume(TokenType::Identifier);
 
@@ -4626,7 +4626,7 @@ NonnullRefPtr<ImportStatement const> Parser::parse_import_statement(Program& pro
             auto namespace_name = consume().value();
             entries_with_location.append({ ImportEntry({}, namespace_name, true), namespace_position });
         } else {
-            syntax_error(DeprecatedString::formatted("Unexpected token: {}", m_state.current_token.name()));
+            syntax_error(ByteString::formatted("Unexpected token: {}", m_state.current_token.name()));
         }
 
     } else if (match(TokenType::CurlyOpen)) {
@@ -4650,7 +4650,7 @@ NonnullRefPtr<ImportStatement const> Parser::parse_import_statement(Program& pro
 
                     entries_with_location.append({ { name, alias }, alias_position });
                 } else if (require_as) {
-                    syntax_error(DeprecatedString::formatted("Unexpected reserved word '{}'", name));
+                    syntax_error(ByteString::formatted("Unexpected reserved word '{}'", name));
                 } else {
                     check_identifier_name_for_assignment_validity(name);
 
@@ -4688,7 +4688,7 @@ NonnullRefPtr<ImportStatement const> Parser::parse_import_statement(Program& pro
 
     auto from_statement = consume(TokenType::Identifier).original_value();
     if (from_statement != "from"sv)
-        syntax_error(DeprecatedString::formatted("Expected 'from' got {}", from_statement));
+        syntax_error(ByteString::formatted("Expected 'from' got {}", from_statement));
 
     auto module_request = parse_module_request();
 
@@ -4698,12 +4698,12 @@ NonnullRefPtr<ImportStatement const> Parser::parse_import_statement(Program& pro
     for (auto& entry : entries_with_location) {
         for (auto& import_statement : program.imports()) {
             if (import_statement->has_bound_name(entry.entry.local_name))
-                syntax_error(DeprecatedString::formatted("Identifier '{}' already declared", entry.entry.local_name), entry.position);
+                syntax_error(ByteString::formatted("Identifier '{}' already declared", entry.entry.local_name), entry.position);
         }
 
         for (auto& new_entry : entries) {
             if (new_entry.local_name == entry.entry.local_name)
-                syntax_error(DeprecatedString::formatted("Identifier '{}' already declared", entry.entry.local_name), entry.position);
+                syntax_error(ByteString::formatted("Identifier '{}' already declared", entry.entry.local_name), entry.position);
         }
 
         entries.append(move(entry.entry));
@@ -5002,12 +5002,12 @@ NonnullRefPtr<ExportStatement const> Parser::parse_export_statement(Program& pro
     for (auto& entry : entries_with_location) {
         for (auto& export_statement : program.exports()) {
             if (export_statement->has_export(entry.entry.export_name))
-                syntax_error(DeprecatedString::formatted("Duplicate export with name: '{}'", entry.entry.export_name), entry.position);
+                syntax_error(ByteString::formatted("Duplicate export with name: '{}'", entry.entry.export_name), entry.position);
         }
 
         for (auto& new_entry : entries) {
             if (new_entry.kind != ExportEntry::Kind::EmptyNamedExport && new_entry.export_name == entry.entry.export_name)
-                syntax_error(DeprecatedString::formatted("Duplicate export with name: '{}'", entry.entry.export_name), entry.position);
+                syntax_error(ByteString::formatted("Duplicate export with name: '{}'", entry.entry.export_name), entry.position);
         }
 
         entries.append(move(entry.entry));
@@ -5101,7 +5101,7 @@ NonnullRefPtr<Identifier const> Parser::create_identifier_and_register_in_curren
     return id;
 }
 
-Parser Parser::parse_function_body_from_string(DeprecatedString const& body_string, u16 parse_options, Vector<FunctionParameter> const& parameters, FunctionKind kind, bool& contains_direct_call_to_eval)
+Parser Parser::parse_function_body_from_string(ByteString const& body_string, u16 parse_options, Vector<FunctionParameter> const& parameters, FunctionKind kind, bool& contains_direct_call_to_eval)
 {
     RefPtr<FunctionBody const> function_body;
 
diff --git a/Userland/Libraries/LibJS/Parser.h b/Userland/Libraries/LibJS/Parser.h
index f244e6fa516..6fe48767a51 100644
--- a/Userland/Libraries/LibJS/Parser.h
+++ b/Userland/Libraries/LibJS/Parser.h
@@ -200,7 +200,7 @@ public:
                 if (!hint.is_empty())
                     warnln("{}", hint);
             }
-            warnln("SyntaxError: {}", error.to_deprecated_string());
+            warnln("SyntaxError: {}", error.to_byte_string());
         }
     }
 
@@ -211,7 +211,7 @@ public:
     // Needs to mess with m_state, and we're not going to expose a non-const getter for that :^)
     friend ThrowCompletionOr<ECMAScriptFunctionObject*> FunctionConstructor::create_dynamic_function(VM&, FunctionObject&, FunctionObject*, FunctionKind, MarkedVector<Value> const&);
 
-    static Parser parse_function_body_from_string(DeprecatedString const& body_string, u16 parse_options, Vector<FunctionParameter> const& parameters, FunctionKind kind, bool& contains_direct_call_to_eval);
+    static Parser parse_function_body_from_string(ByteString const& body_string, u16 parse_options, Vector<FunctionParameter> const& parameters, FunctionKind kind, bool& contains_direct_call_to_eval);
 
 private:
     friend class ScopePusher;
@@ -244,7 +244,7 @@ private:
     bool match(TokenType type) const;
     bool done() const;
     void expected(char const* what);
-    void syntax_error(DeprecatedString const& message, Optional<Position> = {});
+    void syntax_error(ByteString const& message, Optional<Position> = {});
     Token consume();
     Token consume_and_allow_division();
     Token consume_identifier();
diff --git a/Userland/Libraries/LibJS/ParserError.cpp b/Userland/Libraries/LibJS/ParserError.cpp
index d9b05221023..66217f1b309 100644
--- a/Userland/Libraries/LibJS/ParserError.cpp
+++ b/Userland/Libraries/LibJS/ParserError.cpp
@@ -15,31 +15,31 @@ namespace JS {
 ErrorOr<String> ParserError::to_string() const
 {
     if (!position.has_value())
-        return String::from_deprecated_string(message);
+        return String::from_byte_string(message);
     return String::formatted("{} (line: {}, column: {})", message, position.value().line, position.value().column);
 }
 
-DeprecatedString ParserError::to_deprecated_string() const
+ByteString ParserError::to_byte_string() const
 {
     if (!position.has_value())
         return message;
-    return DeprecatedString::formatted("{} (line: {}, column: {})", message, position.value().line, position.value().column);
+    return ByteString::formatted("{} (line: {}, column: {})", message, position.value().line, position.value().column);
 }
 
-DeprecatedString ParserError::source_location_hint(StringView source, char const spacer, char const indicator) const
+ByteString ParserError::source_location_hint(StringView source, char const spacer, char const indicator) const
 {
     if (!position.has_value())
         return {};
     // We need to modify the source to match what the lexer considers one line - normalizing
     // line terminators to \n is easier than splitting using all different LT characters.
-    DeprecatedString source_string = source.replace("\r\n"sv, "\n"sv, ReplaceMode::All).replace("\r"sv, "\n"sv, ReplaceMode::All).replace(LINE_SEPARATOR_STRING, "\n"sv, ReplaceMode::All).replace(PARAGRAPH_SEPARATOR_STRING, "\n"sv, ReplaceMode::All);
+    ByteString source_string = source.replace("\r\n"sv, "\n"sv, ReplaceMode::All).replace("\r"sv, "\n"sv, ReplaceMode::All).replace(LINE_SEPARATOR_STRING, "\n"sv, ReplaceMode::All).replace(PARAGRAPH_SEPARATOR_STRING, "\n"sv, ReplaceMode::All);
     StringBuilder builder;
     builder.append(source_string.split_view('\n', SplitBehavior::KeepEmpty)[position.value().line - 1]);
     builder.append('\n');
     for (size_t i = 0; i < position.value().column - 1; ++i)
         builder.append(spacer);
     builder.append(indicator);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/Userland/Libraries/LibJS/ParserError.h b/Userland/Libraries/LibJS/ParserError.h
index f60928f46b2..48cae7992b4 100644
--- a/Userland/Libraries/LibJS/ParserError.h
+++ b/Userland/Libraries/LibJS/ParserError.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Optional.h>
 #include <AK/String.h>
@@ -16,12 +16,12 @@
 namespace JS {
 
 struct ParserError {
-    DeprecatedString message;
+    ByteString message;
     Optional<Position> position;
 
     ErrorOr<String> to_string() const;
-    DeprecatedString to_deprecated_string() const;
-    DeprecatedString source_location_hint(StringView source, char const spacer = ' ', char const indicator = '^') const;
+    ByteString to_byte_string() const;
+    ByteString source_location_hint(StringView source, char const spacer = ' ', char const indicator = '^') const;
 };
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp b/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp
index c3d12c3855c..e2f43dbfd88 100644
--- a/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp
+++ b/Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp
@@ -579,7 +579,7 @@ ThrowCompletionOr<Value> perform_eval(VM& vm, Value x, CallerMode strict_caller,
         .in_class_field_initializer = in_class_field_initializer,
     };
 
-    Parser parser { Lexer { code_string.deprecated_string() }, Program::Type::Script, move(initial_state) };
+    Parser parser { Lexer { code_string.byte_string() }, Program::Type::Script, move(initial_state) };
     auto program = parser.parse_program(strict_caller == CallerMode::Strict);
 
     //     b. If script is a List of errors, throw a SyntaxError exception.
@@ -1289,7 +1289,7 @@ ThrowCompletionOr<String> get_substitution(VM& vm, Utf16View const& matched, Utf
                 TRY_OR_THROW_OOM(vm, result.try_append(curr));
             } else {
                 auto group_name_view = replace_view.substring_view(start_position, *end_position - start_position);
-                auto group_name = TRY_OR_THROW_OOM(vm, group_name_view.to_deprecated_string(Utf16View::AllowInvalidCodeUnits::Yes));
+                auto group_name = TRY_OR_THROW_OOM(vm, group_name_view.to_byte_string(Utf16View::AllowInvalidCodeUnits::Yes));
 
                 auto capture = TRY(named_captures.as_object().get(group_name));
 
@@ -1505,7 +1505,7 @@ ThrowCompletionOr<Value> perform_import_call(VM& vm, Value specifier, Value opti
 
     // 8. Let specifierString be Completion(ToString(specifier)).
     // 9. IfAbruptRejectPromise(specifierString, promiseCapability).
-    auto specifier_string = TRY_OR_REJECT_WITH_VALUE(vm, promise_capability, specifier.to_deprecated_string(vm));
+    auto specifier_string = TRY_OR_REJECT_WITH_VALUE(vm, promise_capability, specifier.to_byte_string(vm));
 
     // 10. Let attributes be a new empty List.
     Vector<ImportAttribute> attributes;
@@ -1569,7 +1569,7 @@ ThrowCompletionOr<Value> perform_import_call(VM& vm, Value specifier, Value opti
                 }
 
                 // 4. Append the ImportAttribute Record { [[Key]]: key, [[Value]]: value } to attributes.
-                attributes.empend(key.as_string().deprecated_string(), value.as_string().deprecated_string());
+                attributes.empend(key.as_string().byte_string(), value.as_string().byte_string());
             }
         }
 
diff --git a/Userland/Libraries/LibJS/Runtime/AggregateErrorConstructor.cpp b/Userland/Libraries/LibJS/Runtime/AggregateErrorConstructor.cpp
index 3709b3ed176..1284bfb7fa9 100644
--- a/Userland/Libraries/LibJS/Runtime/AggregateErrorConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/AggregateErrorConstructor.cpp
@@ -55,7 +55,7 @@ ThrowCompletionOr<NonnullGCPtr<Object>> AggregateErrorConstructor::construct(Fun
     // 3. If message is not undefined, then
     if (!message.is_undefined()) {
         // a. Let msg be ? ToString(message).
-        auto msg = TRY(message.to_deprecated_string(vm));
+        auto msg = TRY(message.to_byte_string(vm));
 
         // b. Perform CreateNonEnumerableDataPropertyOrThrow(O, "message", msg).
         aggregate_error->create_non_enumerable_data_property_or_throw(vm.names.message, PrimitiveString::create(vm, msg));
diff --git a/Userland/Libraries/LibJS/Runtime/Array.cpp b/Userland/Libraries/LibJS/Runtime/Array.cpp
index f17c7c83a82..fce34e6bb59 100644
--- a/Userland/Libraries/LibJS/Runtime/Array.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Array.cpp
@@ -261,10 +261,10 @@ ThrowCompletionOr<double> compare_array_elements(VM& vm, Value x, Value y, Funct
     }
 
     // 5. Let xString be ? ToString(x).
-    auto x_string = PrimitiveString::create(vm, TRY(x.to_deprecated_string(vm)));
+    auto x_string = PrimitiveString::create(vm, TRY(x.to_byte_string(vm)));
 
     // 6. Let yString be ? ToString(y).
-    auto y_string = PrimitiveString::create(vm, TRY(y.to_deprecated_string(vm)));
+    auto y_string = PrimitiveString::create(vm, TRY(y.to_byte_string(vm)));
 
     // 7. Let xSmaller be ! IsLessThan(xString, yString, true).
     auto x_smaller = MUST(is_less_than(vm, x_string, y_string, true));
diff --git a/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp b/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp
index 86d9a6ae22c..584b49c79ce 100644
--- a/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp
@@ -838,9 +838,9 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::join)
     };
 
     auto length = TRY(length_of_array_like(vm, this_object));
-    DeprecatedString separator = ",";
+    ByteString separator = ",";
     if (!vm.argument(0).is_undefined())
-        separator = TRY(vm.argument(0).to_deprecated_string(vm));
+        separator = TRY(vm.argument(0).to_byte_string(vm));
     StringBuilder builder;
     for (size_t i = 0; i < length; ++i) {
         if (i > 0)
@@ -848,11 +848,11 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::join)
         auto value = TRY(this_object->get(i));
         if (value.is_nullish())
             continue;
-        auto string = TRY(value.to_deprecated_string(vm));
+        auto string = TRY(value.to_byte_string(vm));
         builder.append(string);
     }
 
-    return PrimitiveString::create(vm, builder.to_deprecated_string());
+    return PrimitiveString::create(vm, builder.to_byte_string());
 }
 
 // 23.1.3.19 Array.prototype.keys ( ), https://tc39.es/ecma262/#sec-array.prototype.keys
@@ -1650,7 +1650,7 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::to_locale_string)
             auto locale_string_result = TRY(value.invoke(vm, vm.names.toLocaleString, locales, options));
 
             // ii. Set R to the string-concatenation of R and S.
-            auto string = TRY(locale_string_result.to_deprecated_string(vm));
+            auto string = TRY(locale_string_result.to_byte_string(vm));
             builder.append(string);
         }
 
@@ -1658,7 +1658,7 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::to_locale_string)
     }
 
     // 7. Return R.
-    return PrimitiveString::create(vm, builder.to_deprecated_string());
+    return PrimitiveString::create(vm, builder.to_byte_string());
 }
 
 // 23.1.3.33 Array.prototype.toReversed ( ), https://tc39.es/ecma262/#sec-array.prototype.toreversed
diff --git a/Userland/Libraries/LibJS/Runtime/BigInt.h b/Userland/Libraries/LibJS/Runtime/BigInt.h
index 8d1598fcd7f..498a02adb6a 100644
--- a/Userland/Libraries/LibJS/Runtime/BigInt.h
+++ b/Userland/Libraries/LibJS/Runtime/BigInt.h
@@ -27,7 +27,7 @@ public:
     Crypto::SignedBigInteger const& big_integer() const { return m_big_integer; }
 
     ErrorOr<String> to_string() const;
-    DeprecatedString to_deprecated_string() const { return DeprecatedString::formatted("{}n", m_big_integer.to_base_deprecated(10)); }
+    ByteString to_byte_string() const { return ByteString::formatted("{}n", m_big_integer.to_base_deprecated(10)); }
 
 private:
     explicit BigInt(Crypto::SignedBigInteger);
diff --git a/Userland/Libraries/LibJS/Runtime/BoundFunction.cpp b/Userland/Libraries/LibJS/Runtime/BoundFunction.cpp
index 8a10a55106c..aad2b42a1c3 100644
--- a/Userland/Libraries/LibJS/Runtime/BoundFunction.cpp
+++ b/Userland/Libraries/LibJS/Runtime/BoundFunction.cpp
@@ -40,7 +40,7 @@ BoundFunction::BoundFunction(Realm& realm, FunctionObject& bound_target_function
     , m_bound_this(bound_this)
     , m_bound_arguments(move(bound_arguments))
     // FIXME: Non-standard and redundant, remove.
-    , m_name(DeprecatedString::formatted("bound {}", bound_target_function.name()))
+    , m_name(ByteString::formatted("bound {}", bound_target_function.name()))
 {
 }
 
diff --git a/Userland/Libraries/LibJS/Runtime/Date.cpp b/Userland/Libraries/LibJS/Runtime/Date.cpp
index 2836b8ec433..2e155e692dd 100644
--- a/Userland/Libraries/LibJS/Runtime/Date.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Date.cpp
@@ -719,7 +719,7 @@ double parse_time_zone_offset_string(StringView offset_string)
         auto parsed_fraction = *parse_result->time_zone_utc_offset_fraction;
 
         // b. Let fraction be the string-concatenation of CodePointsToString(parsedFraction) and "000000000".
-        auto fraction = DeprecatedString::formatted("{}000000000", parsed_fraction);
+        auto fraction = ByteString::formatted("{}000000000", parsed_fraction);
 
         // c. Let nanosecondsString be the substring of fraction from 1 to 10.
         auto nanoseconds_string = fraction.substring_view(1, 9);
diff --git a/Userland/Libraries/LibJS/Runtime/DateConstructor.cpp b/Userland/Libraries/LibJS/Runtime/DateConstructor.cpp
index 6b7cd9fd590..30563a153a1 100644
--- a/Userland/Libraries/LibJS/Runtime/DateConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/DateConstructor.cpp
@@ -26,7 +26,7 @@ namespace JS {
 JS_DEFINE_ALLOCATOR(DateConstructor);
 
 // 21.4.3.2 Date.parse ( string ), https://tc39.es/ecma262/#sec-date.parse
-static double parse_simplified_iso8601(DeprecatedString const& iso_8601)
+static double parse_simplified_iso8601(ByteString const& iso_8601)
 {
     // 21.4.1.15 Date Time String Format, https://tc39.es/ecma262/#sec-date-time-string-format
     GenericLexer lexer(iso_8601);
@@ -150,7 +150,7 @@ static double parse_simplified_iso8601(DeprecatedString const& iso_8601)
     return time_clip(time_ms);
 }
 
-static double parse_date_string(DeprecatedString const& date_string)
+static double parse_date_string(ByteString const& date_string)
 {
     auto value = parse_simplified_iso8601(date_string);
     if (isfinite(value))
@@ -246,7 +246,7 @@ ThrowCompletionOr<NonnullGCPtr<Object>> DateConstructor::construct(FunctionObjec
             if (primitive.is_string()) {
                 // 1. Assert: The next step never returns an abrupt completion because Type(v) is String.
                 // 2. Let tv be the result of parsing v as a date, in exactly the same manner as for the parse method (21.4.3.2).
-                time_value = parse_date_string(primitive.as_string().deprecated_string());
+                time_value = parse_date_string(primitive.as_string().byte_string());
             }
             // iii. Else,
             else {
@@ -321,7 +321,7 @@ JS_DEFINE_NATIVE_FUNCTION(DateConstructor::parse)
     if (!vm.argument_count())
         return js_nan();
 
-    auto date_string = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto date_string = TRY(vm.argument(0).to_byte_string(vm));
 
     return Value(parse_date_string(date_string));
 }
diff --git a/Userland/Libraries/LibJS/Runtime/DatePrototype.cpp b/Userland/Libraries/LibJS/Runtime/DatePrototype.cpp
index 19783b99632..e8a473268c9 100644
--- a/Userland/Libraries/LibJS/Runtime/DatePrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/DatePrototype.cpp
@@ -7,8 +7,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/DateConstants.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Function.h>
 #include <AK/TypeCasts.h>
 #include <LibCore/DateTime.h>
@@ -1068,7 +1068,7 @@ JS_DEFINE_NATIVE_FUNCTION(DatePrototype::to_string)
 }
 
 // 21.4.4.41.1 TimeString ( tv ), https://tc39.es/ecma262/#sec-timestring
-DeprecatedString time_string(double time)
+ByteString time_string(double time)
 {
     // 1. Let hour be ToZeroPaddedDecimalString(ℝ(HourFromTime(tv)), 2).
     auto hour = hour_from_time(time);
@@ -1080,11 +1080,11 @@ DeprecatedString time_string(double time)
     auto second = sec_from_time(time);
 
     // 4. Return the string-concatenation of hour, ":", minute, ":", second, the code unit 0x0020 (SPACE), and "GMT".
-    return DeprecatedString::formatted("{:02}:{:02}:{:02} GMT", hour, minute, second);
+    return ByteString::formatted("{:02}:{:02}:{:02} GMT", hour, minute, second);
 }
 
 // 21.4.4.41.2 DateString ( tv ), https://tc39.es/ecma262/#sec-datestring
-DeprecatedString date_string(double time)
+ByteString date_string(double time)
 {
     // 1. Let weekday be the Name of the entry in Table 62 with the Number WeekDay(tv).
     auto weekday = short_day_names[week_day(time)];
@@ -1103,11 +1103,11 @@ DeprecatedString date_string(double time)
 
     // 6. Let paddedYear be ToZeroPaddedDecimalString(abs(ℝ(yv)), 4).
     // 7. Return the string-concatenation of weekday, the code unit 0x0020 (SPACE), month, the code unit 0x0020 (SPACE), day, the code unit 0x0020 (SPACE), yearSign, and paddedYear.
-    return DeprecatedString::formatted("{} {} {:02} {}{:04}", weekday, month, day, year_sign, abs(year));
+    return ByteString::formatted("{} {} {:02} {}{:04}", weekday, month, day, year_sign, abs(year));
 }
 
 // 21.4.4.41.3 TimeZoneString ( tv ), https://tc39.es/ecma262/#sec-timezoneestring
-DeprecatedString time_zone_string(double time)
+ByteString time_zone_string(double time)
 {
     // 1. Let systemTimeZoneIdentifier be SystemTimeZoneIdentifier().
     auto system_time_zone_identifier = JS::system_time_zone_identifier();
@@ -1161,11 +1161,11 @@ DeprecatedString time_zone_string(double time)
     }
 
     // 10. Return the string-concatenation of offsetSign, offsetHour, offsetMin, and tzName.
-    return DeprecatedString::formatted("{}{:02}{:02} ({})", offset_sign, offset_hour, offset_min, tz_name);
+    return ByteString::formatted("{}{:02}{:02} ({})", offset_sign, offset_hour, offset_min, tz_name);
 }
 
 // 21.4.4.41.4 ToDateString ( tv ), https://tc39.es/ecma262/#sec-todatestring
-DeprecatedString to_date_string(double time)
+ByteString to_date_string(double time)
 {
     // 1. If tv is NaN, return "Invalid Date".
     if (Value(time).is_nan())
@@ -1175,7 +1175,7 @@ DeprecatedString to_date_string(double time)
     time = local_time(time);
 
     // 3. Return the string-concatenation of DateString(t), the code unit 0x0020 (SPACE), TimeString(t), and TimeZoneString(tv).
-    return DeprecatedString::formatted("{} {}{}", date_string(time), time_string(time), time_zone_string(time));
+    return ByteString::formatted("{} {}{}", date_string(time), time_string(time), time_zone_string(time));
 }
 
 // 14.1.1 Date.prototype.toTemporalInstant ( ), https://tc39.es/proposal-temporal/#sec-date.prototype.totemporalinstant
@@ -1205,7 +1205,7 @@ JS_DEFINE_NATIVE_FUNCTION(DatePrototype::to_time_string)
 
     // 4. Let t be LocalTime(tv).
     // 5. Return the string-concatenation of TimeString(t) and TimeZoneString(tv).
-    auto string = DeprecatedString::formatted("{}{}", time_string(local_time(time)), time_zone_string(time));
+    auto string = ByteString::formatted("{}{}", time_string(local_time(time)), time_zone_string(time));
     return PrimitiveString::create(vm, move(string));
 }
 
@@ -1237,7 +1237,7 @@ JS_DEFINE_NATIVE_FUNCTION(DatePrototype::to_utc_string)
 
     // 9. Let paddedYear be ToZeroPaddedDecimalString(abs(ℝ(yv)), 4).
     // 10. Return the string-concatenation of weekday, ",", the code unit 0x0020 (SPACE), day, the code unit 0x0020 (SPACE), month, the code unit 0x0020 (SPACE), yearSign, paddedYear, the code unit 0x0020 (SPACE), and TimeString(tv).
-    auto string = DeprecatedString::formatted("{}, {:02} {} {}{:04} {}", weekday, day, month, year_sign, abs(year), time_string(time));
+    auto string = ByteString::formatted("{}, {:02} {} {}{:04} {}", weekday, day, month, year_sign, abs(year), time_string(time));
     return PrimitiveString::create(vm, move(string));
 }
 
@@ -1250,7 +1250,7 @@ JS_DEFINE_NATIVE_FUNCTION(DatePrototype::symbol_to_primitive)
     auto hint_value = vm.argument(0);
     if (!hint_value.is_string())
         return vm.throw_completion<TypeError>(ErrorType::InvalidHint, hint_value.to_string_without_side_effects());
-    auto hint = hint_value.as_string().deprecated_string();
+    auto hint = hint_value.as_string().byte_string();
     Value::PreferredType try_first;
     if (hint == "string" || hint == "default")
         try_first = Value::PreferredType::String;
diff --git a/Userland/Libraries/LibJS/Runtime/DatePrototype.h b/Userland/Libraries/LibJS/Runtime/DatePrototype.h
index 8b4bb405997..49135b179d6 100644
--- a/Userland/Libraries/LibJS/Runtime/DatePrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/DatePrototype.h
@@ -74,9 +74,9 @@ private:
 };
 
 ThrowCompletionOr<double> this_time_value(VM&, Value value);
-DeprecatedString time_string(double time);
-DeprecatedString date_string(double time);
-DeprecatedString time_zone_string(double time);
-DeprecatedString to_date_string(double time);
+ByteString time_string(double time);
+ByteString date_string(double time);
+ByteString time_zone_string(double time);
+ByteString to_date_string(double time);
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp b/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
index e68630b6e76..0ebcaaa135b 100644
--- a/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
@@ -33,7 +33,7 @@ namespace JS {
 
 JS_DEFINE_ALLOCATOR(ECMAScriptFunctionObject);
 
-NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
+NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
 {
     Object* prototype = nullptr;
     switch (kind) {
@@ -53,12 +53,12 @@ NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& r
     return realm.heap().allocate<ECMAScriptFunctionObject>(realm, move(name), move(source_text), ecmascript_code, move(parameters), m_function_length, move(local_variables_names), parent_environment, private_environment, *prototype, kind, is_strict, might_need_arguments_object, contains_direct_call_to_eval, is_arrow_function, move(class_field_initializer_name));
 }
 
-NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, Object& prototype, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
+NonnullGCPtr<ECMAScriptFunctionObject> ECMAScriptFunctionObject::create(Realm& realm, DeprecatedFlyString name, Object& prototype, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind kind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
 {
     return realm.heap().allocate<ECMAScriptFunctionObject>(realm, move(name), move(source_text), ecmascript_code, move(parameters), m_function_length, move(local_variables_names), parent_environment, private_environment, prototype, kind, is_strict, might_need_arguments_object, contains_direct_call_to_eval, is_arrow_function, move(class_field_initializer_name));
 }
 
-ECMAScriptFunctionObject::ECMAScriptFunctionObject(DeprecatedFlyString name, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> formal_parameters, i32 function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, Object& prototype, FunctionKind kind, bool strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
+ECMAScriptFunctionObject::ECMAScriptFunctionObject(DeprecatedFlyString name, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> formal_parameters, i32 function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, Object& prototype, FunctionKind kind, bool strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name)
     : FunctionObject(prototype)
     , m_name(move(name))
     , m_function_length(function_length)
@@ -1186,7 +1186,7 @@ Completion ECMAScriptFunctionObject::ordinary_call_evaluate_body()
             if (!parameter.default_value)
                 continue;
             if (parameter.bytecode_executable.is_null()) {
-                auto executable = TRY(Bytecode::compile(vm, *parameter.default_value, FunctionKind::Normal, DeprecatedString::formatted("default parameter #{} for {}", default_parameter_index++, m_name)));
+                auto executable = TRY(Bytecode::compile(vm, *parameter.default_value, FunctionKind::Normal, ByteString::formatted("default parameter #{} for {}", default_parameter_index++, m_name)));
                 const_cast<FunctionParameter&>(parameter).bytecode_executable = executable;
                 m_default_parameter_bytecode_executables.append(move(executable));
             } else {
diff --git a/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.h b/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.h
index 32256877d77..fe1108bde50 100644
--- a/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.h
+++ b/Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.h
@@ -38,8 +38,8 @@ public:
         Global,
     };
 
-    static NonnullGCPtr<ECMAScriptFunctionObject> create(Realm&, DeprecatedFlyString name, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind, bool is_strict, bool might_need_arguments_object = true, bool contains_direct_call_to_eval = true, bool is_arrow_function = false, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name = {});
-    static NonnullGCPtr<ECMAScriptFunctionObject> create(Realm&, DeprecatedFlyString name, Object& prototype, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind, bool is_strict, bool might_need_arguments_object = true, bool contains_direct_call_to_eval = true, bool is_arrow_function = false, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name = {});
+    static NonnullGCPtr<ECMAScriptFunctionObject> create(Realm&, DeprecatedFlyString name, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind, bool is_strict, bool might_need_arguments_object = true, bool contains_direct_call_to_eval = true, bool is_arrow_function = false, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name = {});
+    static NonnullGCPtr<ECMAScriptFunctionObject> create(Realm&, DeprecatedFlyString name, Object& prototype, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, FunctionKind, bool is_strict, bool might_need_arguments_object = true, bool contains_direct_call_to_eval = true, bool is_arrow_function = false, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name = {});
 
     virtual void initialize(Realm&) override;
     virtual ~ECMAScriptFunctionObject() override = default;
@@ -73,8 +73,8 @@ public:
     Object* home_object() const { return m_home_object; }
     void set_home_object(Object* home_object) { m_home_object = home_object; }
 
-    DeprecatedString const& source_text() const { return m_source_text; }
-    void set_source_text(DeprecatedString source_text) { m_source_text = move(source_text); }
+    ByteString const& source_text() const { return m_source_text; }
+    void set_source_text(ByteString source_text) { m_source_text = move(source_text); }
 
     Vector<ClassFieldDefinition> const& fields() const { return m_fields; }
     void add_field(ClassFieldDefinition field) { m_fields.append(move(field)); }
@@ -104,7 +104,7 @@ protected:
     virtual Completion ordinary_call_evaluate_body();
 
 private:
-    ECMAScriptFunctionObject(DeprecatedFlyString name, DeprecatedString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, Object& prototype, FunctionKind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name);
+    ECMAScriptFunctionObject(DeprecatedFlyString name, ByteString source_text, Statement const& ecmascript_code, Vector<FunctionParameter> parameters, i32 m_function_length, Vector<DeprecatedFlyString> local_variables_names, Environment* parent_environment, PrivateEnvironment* private_environment, Object& prototype, FunctionKind, bool is_strict, bool might_need_arguments_object, bool contains_direct_call_to_eval, bool is_arrow_function, Variant<PropertyKey, PrivateName, Empty> class_field_initializer_name);
 
     virtual bool is_ecmascript_function_object() const override { return true; }
     virtual void visit_edges(Visitor&) override;
@@ -130,7 +130,7 @@ private:
     GCPtr<Realm> m_realm;                                                    // [[Realm]]
     ScriptOrModule m_script_or_module;                                       // [[ScriptOrModule]]
     GCPtr<Object> m_home_object;                                             // [[HomeObject]]
-    DeprecatedString m_source_text;                                          // [[SourceText]]
+    ByteString m_source_text;                                                // [[SourceText]]
     Vector<ClassFieldDefinition> m_fields;                                   // [[Fields]]
     Vector<PrivateElement> m_private_methods;                                // [[PrivateMethods]]
     Variant<PropertyKey, PrivateName, Empty> m_class_field_initializer_name; // [[ClassFieldInitializerName]]
diff --git a/Userland/Libraries/LibJS/Runtime/Error.cpp b/Userland/Libraries/LibJS/Runtime/Error.cpp
index 11087619f92..a92f5e8e9ec 100644
--- a/Userland/Libraries/LibJS/Runtime/Error.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Error.cpp
@@ -85,7 +85,7 @@ void Error::populate_stack()
         if (element.source_range.has_value())
             range = element.source_range.value();
         TracebackFrame frame {
-            .function_name = context->function_name ? context->function_name->deprecated_string() : "",
+            .function_name = context->function_name ? context->function_name->byte_string() : "",
             .source_range_storage = range,
         };
 
diff --git a/Userland/Libraries/LibJS/Runtime/FunctionConstructor.cpp b/Userland/Libraries/LibJS/Runtime/FunctionConstructor.cpp
index e59f2bd7173..9e6ab208224 100644
--- a/Userland/Libraries/LibJS/Runtime/FunctionConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/FunctionConstructor.cpp
@@ -115,7 +115,7 @@ ThrowCompletionOr<ECMAScriptFunctionObject*> FunctionConstructor::create_dynamic
     auto arg_count = args.size();
 
     // 9. Let P be the empty String.
-    DeprecatedString parameters_string = "";
+    ByteString parameters_string = "";
 
     Optional<Value> body_arg;
 
@@ -140,29 +140,29 @@ ThrowCompletionOr<ECMAScriptFunctionObject*> FunctionConstructor::create_dynamic
         size_t k = 0;
 
         // e. Repeat, while k < argCount - 1,
-        Vector<DeprecatedString> parameters;
+        Vector<ByteString> parameters;
         for (; k < arg_count - 1; ++k) {
             // i. Let nextArg be args[k].
             auto next_arg = args[k];
 
             // ii. Let nextArgString be ? ToString(nextArg).
             // iii. Set P to the string-concatenation of P, "," (a comma), and nextArgString.
-            parameters.append(TRY(next_arg.to_deprecated_string(vm)));
+            parameters.append(TRY(next_arg.to_byte_string(vm)));
 
             // iv. Set k to k + 1.
         }
-        parameters_string = DeprecatedString::join(',', parameters);
+        parameters_string = ByteString::join(',', parameters);
 
         // f. Let bodyArg be args[k].
         body_arg = args[k];
     }
 
     // 13. Let bodyString be the string-concatenation of 0x000A (LINE FEED), ? ToString(bodyArg), and 0x000A (LINE FEED).
-    auto body_string = DeprecatedString::formatted("\n{}\n", body_arg.has_value() ? TRY(body_arg->to_deprecated_string(vm)) : "");
+    auto body_string = ByteString::formatted("\n{}\n", body_arg.has_value() ? TRY(body_arg->to_byte_string(vm)) : "");
 
     // 14. Let sourceString be the string-concatenation of prefix, " anonymous(", P, 0x000A (LINE FEED), ") {", bodyString, and "}".
     // 15. Let sourceText be StringToCodePoints(sourceString).
-    auto source_text = DeprecatedString::formatted("{} anonymous({}\n) {{{}}}", prefix, parameters_string, body_string);
+    auto source_text = ByteString::formatted("{} anonymous({}\n) {{{}}}", prefix, parameters_string, body_string);
 
     u8 parse_options = FunctionNodeParseOptions::CheckForFunctionAndName;
     if (kind == FunctionKind::Async || kind == FunctionKind::AsyncGenerator)
diff --git a/Userland/Libraries/LibJS/Runtime/FunctionObject.cpp b/Userland/Libraries/LibJS/Runtime/FunctionObject.cpp
index 3a5507d2cb3..fe7d2e9f77d 100644
--- a/Userland/Libraries/LibJS/Runtime/FunctionObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/FunctionObject.cpp
@@ -32,7 +32,7 @@ void FunctionObject::set_function_name(Variant<PropertyKey, PrivateName> const&
     VERIFY(m_is_extensible);
     VERIFY(!storage_has(vm.names.name));
 
-    DeprecatedString name;
+    ByteString name;
 
     // 2. If Type(name) is Symbol, then
     if (auto const* property_key = name_arg.get_pointer<PropertyKey>(); property_key && property_key->is_symbol()) {
@@ -41,10 +41,10 @@ void FunctionObject::set_function_name(Variant<PropertyKey, PrivateName> const&
 
         // b. If description is undefined, set name to the empty String.
         if (!description.has_value())
-            name = DeprecatedString::empty();
+            name = ByteString::empty();
         // c. Else, set name to the string-concatenation of "[", description, and "]".
         else
-            name = DeprecatedString::formatted("[{}]", *description);
+            name = ByteString::formatted("[{}]", *description);
     }
     // 3. Else if name is a Private Name, then
     else if (auto const* private_name = name_arg.get_pointer<PrivateName>()) {
@@ -65,7 +65,7 @@ void FunctionObject::set_function_name(Variant<PropertyKey, PrivateName> const&
     // 5. If prefix is present, then
     if (prefix.has_value()) {
         // a. Set name to the string-concatenation of prefix, the code unit 0x0020 (SPACE), and name.
-        name = DeprecatedString::formatted("{} {}", *prefix, name);
+        name = ByteString::formatted("{} {}", *prefix, name);
 
         // b. If F has an [[InitialName]] internal slot, then
         if (is<NativeFunction>(this)) {
diff --git a/Userland/Libraries/LibJS/Runtime/FunctionPrototype.cpp b/Userland/Libraries/LibJS/Runtime/FunctionPrototype.cpp
index 2c29f37be6c..b0759b9b254 100644
--- a/Userland/Libraries/LibJS/Runtime/FunctionPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/FunctionPrototype.cpp
@@ -160,7 +160,7 @@ JS_DEFINE_NATIVE_FUNCTION(FunctionPrototype::to_string)
         // NOTE: once we remove name(), the fallback here can simply be an empty string.
         auto const& native_function = static_cast<NativeFunction&>(function);
         auto const name = native_function.initial_name().value_or(native_function.name());
-        return PrimitiveString::create(vm, DeprecatedString::formatted("function {}() {{ [native code] }}", name));
+        return PrimitiveString::create(vm, ByteString::formatted("function {}() {{ [native code] }}", name));
     }
 
     // 4. If Type(func) is Object and IsCallable(func) is true, return an implementation-defined String source code representation of func. The representation must have the syntax of a NativeFunction.
diff --git a/Userland/Libraries/LibJS/Runtime/GlobalObject.cpp b/Userland/Libraries/LibJS/Runtime/GlobalObject.cpp
index e4096c08476..39ce41ff8c8 100644
--- a/Userland/Libraries/LibJS/Runtime/GlobalObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/GlobalObject.cpp
@@ -387,7 +387,7 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::parse_int)
 }
 
 // 19.2.6.5 Encode ( string, extraUnescaped ), https://tc39.es/ecma262/#sec-encode
-static ThrowCompletionOr<DeprecatedString> encode(VM& vm, DeprecatedString const& string, StringView unescaped_set)
+static ThrowCompletionOr<ByteString> encode(VM& vm, ByteString const& string, StringView unescaped_set)
 {
     auto utf16_string = Utf16String::create(string);
 
@@ -441,12 +441,12 @@ static ThrowCompletionOr<DeprecatedString> encode(VM& vm, DeprecatedString const
             VERIFY(nwritten > 0);
         }
     }
-    return encoded_builder.to_deprecated_string();
+    return encoded_builder.to_byte_string();
 }
 
 // 19.2.6.6 Decode ( string, preserveEscapeSet ), https://tc39.es/ecma262/#sec-decode
 // FIXME: Add spec comments to this implementation. It deviates a lot, so that's a bit tricky.
-static ThrowCompletionOr<DeprecatedString> decode(VM& vm, DeprecatedString const& string, StringView reserved_set)
+static ThrowCompletionOr<ByteString> decode(VM& vm, ByteString const& string, StringView reserved_set)
 {
     StringBuilder decoded_builder;
     auto code_point_start_offset = 0u;
@@ -500,14 +500,14 @@ static ThrowCompletionOr<DeprecatedString> decode(VM& vm, DeprecatedString const
     }
     if (expected_continuation_bytes > 0)
         return vm.throw_completion<URIError>(ErrorType::URIMalformed);
-    return decoded_builder.to_deprecated_string();
+    return decoded_builder.to_byte_string();
 }
 
 // 19.2.6.1 decodeURI ( encodedURI ), https://tc39.es/ecma262/#sec-decodeuri-encodeduri
 JS_DEFINE_NATIVE_FUNCTION(GlobalObject::decode_uri)
 {
     // 1. Let uriString be ? ToString(encodedURI).
-    auto uri_string = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto uri_string = TRY(vm.argument(0).to_byte_string(vm));
 
     // 2. Let preserveEscapeSet be ";/?:@&=+$,#".
     // 3. Return ? Decode(uriString, preserveEscapeSet).
@@ -521,7 +521,7 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::decode_uri_component)
     auto encoded_uri_component = vm.argument(0);
 
     // 1. Let componentString be ? ToString(encodedURIComponent).
-    auto uri_string = TRY(encoded_uri_component.to_deprecated_string(vm));
+    auto uri_string = TRY(encoded_uri_component.to_byte_string(vm));
 
     // 2. Let preserveEscapeSet be the empty String.
     // 3. Return ? Decode(componentString, preserveEscapeSet).
@@ -535,7 +535,7 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::encode_uri)
     auto uri = vm.argument(0);
 
     // 1. Let uriString be ? ToString(uri).
-    auto uri_string = TRY(uri.to_deprecated_string(vm));
+    auto uri_string = TRY(uri.to_byte_string(vm));
 
     // 2. Let extraUnescaped be ";/?:@&=+$,#".
     // 3. Return ? Encode(uriString, extraUnescaped).
@@ -549,7 +549,7 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::encode_uri_component)
     auto uri_component = vm.argument(0);
 
     // 1. Let componentString be ? ToString(uriComponent).
-    auto uri_string = TRY(uri_component.to_deprecated_string(vm));
+    auto uri_string = TRY(uri_component.to_byte_string(vm));
 
     // 2. Let extraUnescaped be the empty String.
     // 3. Return ? Encode(componentString, extraUnescaped).
@@ -561,7 +561,7 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::encode_uri_component)
 JS_DEFINE_NATIVE_FUNCTION(GlobalObject::escape)
 {
     // 1. Set string to ? ToString(string).
-    auto string = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto string = TRY(vm.argument(0).to_byte_string(vm));
 
     // 3. Let R be the empty String.
     StringBuilder escaped;
@@ -601,14 +601,14 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::escape)
     }
 
     // 7. Return R.
-    return PrimitiveString::create(vm, escaped.to_deprecated_string());
+    return PrimitiveString::create(vm, escaped.to_byte_string());
 }
 
 // B.2.1.2 unescape ( string ), https://tc39.es/ecma262/#sec-unescape-string
 JS_DEFINE_NATIVE_FUNCTION(GlobalObject::unescape)
 {
     // 1. Set string to ? ToString(string).
-    auto string = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto string = TRY(vm.argument(0).to_byte_string(vm));
 
     // 2. Let length be the length of string.
     ssize_t length = string.length();
@@ -658,7 +658,7 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::unescape)
     }
 
     // 6. Return R.
-    return PrimitiveString::create(vm, unescaped.to_deprecated_string());
+    return PrimitiveString::create(vm, unescaped.to_byte_string());
 }
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Intl/DurationFormat.cpp b/Userland/Libraries/LibJS/Runtime/Intl/DurationFormat.cpp
index 0b596956bce..471f52d62fd 100644
--- a/Userland/Libraries/LibJS/Runtime/Intl/DurationFormat.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Intl/DurationFormat.cpp
@@ -275,7 +275,7 @@ bool is_valid_duration_record(Temporal::DurationRecord const& record)
 ThrowCompletionOr<DurationUnitOptions> get_duration_unit_options(VM& vm, String const& unit, Object const& options, StringView base_style, ReadonlySpan<StringView> styles_list, StringView digital_base, StringView previous_style)
 {
     // 1. Let style be ? GetOption(options, unit, string, stylesList, undefined).
-    auto style_value = TRY(get_option(vm, options, unit.to_deprecated_string(), OptionType::String, styles_list, Empty {}));
+    auto style_value = TRY(get_option(vm, options, unit.to_byte_string(), OptionType::String, styles_list, Empty {}));
 
     // 2. Let displayDefault be "always".
     auto display_default = "always"sv;
@@ -319,7 +319,7 @@ ThrowCompletionOr<DurationUnitOptions> get_duration_unit_options(VM& vm, String
     auto display_field = MUST(String::formatted("{}Display", unit));
 
     // 5. Let display be ? GetOption(options, displayField, string, « "auto", "always" », displayDefault).
-    auto display = TRY(get_option(vm, options, display_field.to_deprecated_string(), OptionType::String, { "auto"sv, "always"sv }, display_default));
+    auto display = TRY(get_option(vm, options, display_field.to_byte_string(), OptionType::String, { "auto"sv, "always"sv }, display_default));
 
     // 6. If prevStyle is "numeric" or "2-digit", then
     if (previous_style == "numeric"sv || previous_style == "2-digit"sv) {
diff --git a/Userland/Libraries/LibJS/Runtime/JSONObject.cpp b/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
index c01952a75e0..9ebd3d4eb46 100644
--- a/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/JSONObject.cpp
@@ -47,7 +47,7 @@ void JSONObject::initialize(Realm& realm)
 }
 
 // 25.5.2 JSON.stringify ( value [ , replacer [ , space ] ] ), https://tc39.es/ecma262/#sec-json.stringify
-ThrowCompletionOr<Optional<DeprecatedString>> JSONObject::stringify_impl(VM& vm, Value value, Value replacer, Value space)
+ThrowCompletionOr<Optional<ByteString>> JSONObject::stringify_impl(VM& vm, Value value, Value replacer, Value space)
 {
     auto& realm = *vm.current_realm();
 
@@ -61,18 +61,18 @@ ThrowCompletionOr<Optional<DeprecatedString>> JSONObject::stringify_impl(VM& vm,
             if (is_array) {
                 auto& replacer_object = replacer.as_object();
                 auto replacer_length = TRY(length_of_array_like(vm, replacer_object));
-                Vector<DeprecatedString> list;
+                Vector<ByteString> list;
                 for (size_t i = 0; i < replacer_length; ++i) {
                     auto replacer_value = TRY(replacer_object.get(i));
-                    Optional<DeprecatedString> item;
+                    Optional<ByteString> item;
                     if (replacer_value.is_string()) {
-                        item = replacer_value.as_string().deprecated_string();
+                        item = replacer_value.as_string().byte_string();
                     } else if (replacer_value.is_number()) {
-                        item = MUST(replacer_value.to_deprecated_string(vm));
+                        item = MUST(replacer_value.to_byte_string(vm));
                     } else if (replacer_value.is_object()) {
                         auto& value_object = replacer_value.as_object();
                         if (is<StringObject>(value_object) || is<NumberObject>(value_object))
-                            item = TRY(replacer_value.to_deprecated_string(vm));
+                            item = TRY(replacer_value.to_byte_string(vm));
                     }
                     if (item.has_value() && !list.contains_slow(*item)) {
                         list.append(*item);
@@ -94,20 +94,20 @@ ThrowCompletionOr<Optional<DeprecatedString>> JSONObject::stringify_impl(VM& vm,
     if (space.is_number()) {
         auto space_mv = MUST(space.to_integer_or_infinity(vm));
         space_mv = min(10, space_mv);
-        state.gap = space_mv < 1 ? DeprecatedString::empty() : DeprecatedString::repeated(' ', space_mv);
+        state.gap = space_mv < 1 ? ByteString::empty() : ByteString::repeated(' ', space_mv);
     } else if (space.is_string()) {
-        auto string = space.as_string().deprecated_string();
+        auto string = space.as_string().byte_string();
         if (string.length() <= 10)
             state.gap = string;
         else
             state.gap = string.substring(0, 10);
     } else {
-        state.gap = DeprecatedString::empty();
+        state.gap = ByteString::empty();
     }
 
     auto wrapper = Object::create(realm, realm.intrinsics().object_prototype());
-    MUST(wrapper->create_data_property_or_throw(DeprecatedString::empty(), value));
-    return serialize_json_property(vm, state, DeprecatedString::empty(), wrapper);
+    MUST(wrapper->create_data_property_or_throw(ByteString::empty(), value));
+    return serialize_json_property(vm, state, ByteString::empty(), wrapper);
 }
 
 // 25.5.2 JSON.stringify ( value [ , replacer [ , space ] ] ), https://tc39.es/ecma262/#sec-json.stringify
@@ -128,7 +128,7 @@ JS_DEFINE_NATIVE_FUNCTION(JSONObject::stringify)
 }
 
 // 25.5.2.1 SerializeJSONProperty ( state, key, holder ), https://tc39.es/ecma262/#sec-serializejsonproperty
-ThrowCompletionOr<Optional<DeprecatedString>> JSONObject::serialize_json_property(VM& vm, StringifyState& state, PropertyKey const& key, Object* holder)
+ThrowCompletionOr<Optional<ByteString>> JSONObject::serialize_json_property(VM& vm, StringifyState& state, PropertyKey const& key, Object* holder)
 {
     // 1. Let value be ? Get(holder, key).
     auto value = TRY(holder->get(key));
@@ -188,13 +188,13 @@ ThrowCompletionOr<Optional<DeprecatedString>> JSONObject::serialize_json_propert
 
     // 8. If Type(value) is String, return QuoteJSONString(value).
     if (value.is_string())
-        return quote_json_string(value.as_string().deprecated_string());
+        return quote_json_string(value.as_string().byte_string());
 
     // 9. If Type(value) is Number, then
     if (value.is_number()) {
         // a. If value is finite, return ! ToString(value).
         if (value.is_finite_number())
-            return MUST(value.to_deprecated_string(vm));
+            return MUST(value.to_byte_string(vm));
 
         // b. Return "null".
         return "null"sv;
@@ -218,26 +218,26 @@ ThrowCompletionOr<Optional<DeprecatedString>> JSONObject::serialize_json_propert
     }
 
     // 12. Return undefined.
-    return Optional<DeprecatedString> {};
+    return Optional<ByteString> {};
 }
 
 // 25.5.2.4 SerializeJSONObject ( state, value ), https://tc39.es/ecma262/#sec-serializejsonobject
-ThrowCompletionOr<DeprecatedString> JSONObject::serialize_json_object(VM& vm, StringifyState& state, Object& object)
+ThrowCompletionOr<ByteString> JSONObject::serialize_json_object(VM& vm, StringifyState& state, Object& object)
 {
     if (state.seen_objects.contains(&object))
         return vm.throw_completion<TypeError>(ErrorType::JsonCircular);
 
     state.seen_objects.set(&object);
-    DeprecatedString previous_indent = state.indent;
-    state.indent = DeprecatedString::formatted("{}{}", state.indent, state.gap);
-    Vector<DeprecatedString> property_strings;
+    ByteString previous_indent = state.indent;
+    state.indent = ByteString::formatted("{}{}", state.indent, state.gap);
+    Vector<ByteString> property_strings;
 
     auto process_property = [&](PropertyKey const& key) -> ThrowCompletionOr<void> {
         if (key.is_symbol())
             return {};
         auto serialized_property_string = TRY(serialize_json_property(vm, state, key, &object));
         if (serialized_property_string.has_value()) {
-            property_strings.append(DeprecatedString::formatted(
+            property_strings.append(ByteString::formatted(
                 "{}:{}{}",
                 quote_json_string(key.to_string()),
                 state.gap.is_empty() ? "" : " ",
@@ -253,7 +253,7 @@ ThrowCompletionOr<DeprecatedString> JSONObject::serialize_json_object(VM& vm, St
     } else {
         auto property_list = TRY(object.enumerable_own_property_names(PropertyKind::Key));
         for (auto& property : property_list)
-            TRY(process_property(property.as_string().deprecated_string()));
+            TRY(process_property(property.as_string().byte_string()));
     }
     StringBuilder builder;
     if (property_strings.is_empty()) {
@@ -271,7 +271,7 @@ ThrowCompletionOr<DeprecatedString> JSONObject::serialize_json_object(VM& vm, St
         } else {
             builder.append('\n');
             builder.append(state.indent);
-            auto separator = DeprecatedString::formatted(",\n{}", state.indent);
+            auto separator = ByteString::formatted(",\n{}", state.indent);
             for (auto& property_string : property_strings) {
                 if (!first)
                     builder.append(separator);
@@ -286,19 +286,19 @@ ThrowCompletionOr<DeprecatedString> JSONObject::serialize_json_object(VM& vm, St
 
     state.seen_objects.remove(&object);
     state.indent = previous_indent;
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // 25.5.2.5 SerializeJSONArray ( state, value ), https://tc39.es/ecma262/#sec-serializejsonarray
-ThrowCompletionOr<DeprecatedString> JSONObject::serialize_json_array(VM& vm, StringifyState& state, Object& object)
+ThrowCompletionOr<ByteString> JSONObject::serialize_json_array(VM& vm, StringifyState& state, Object& object)
 {
     if (state.seen_objects.contains(&object))
         return vm.throw_completion<TypeError>(ErrorType::JsonCircular);
 
     state.seen_objects.set(&object);
-    DeprecatedString previous_indent = state.indent;
-    state.indent = DeprecatedString::formatted("{}{}", state.indent, state.gap);
-    Vector<DeprecatedString> property_strings;
+    ByteString previous_indent = state.indent;
+    state.indent = ByteString::formatted("{}{}", state.indent, state.gap);
+    Vector<ByteString> property_strings;
 
     auto length = TRY(length_of_array_like(vm, object));
 
@@ -331,7 +331,7 @@ ThrowCompletionOr<DeprecatedString> JSONObject::serialize_json_array(VM& vm, Str
         } else {
             builder.append("[\n"sv);
             builder.append(state.indent);
-            auto separator = DeprecatedString::formatted(",\n{}", state.indent);
+            auto separator = ByteString::formatted(",\n{}", state.indent);
             bool first = true;
             for (auto& property_string : property_strings) {
                 if (!first)
@@ -347,11 +347,11 @@ ThrowCompletionOr<DeprecatedString> JSONObject::serialize_json_array(VM& vm, Str
 
     state.seen_objects.remove(&object);
     state.indent = previous_indent;
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // 25.5.2.2 QuoteJSONString ( value ), https://tc39.es/ecma262/#sec-quotejsonstring
-DeprecatedString JSONObject::quote_json_string(DeprecatedString string)
+ByteString JSONObject::quote_json_string(ByteString string)
 {
     // 1. Let product be the String value consisting solely of the code unit 0x0022 (QUOTATION MARK).
     StringBuilder builder;
@@ -402,7 +402,7 @@ DeprecatedString JSONObject::quote_json_string(DeprecatedString string)
     builder.append('"');
 
     // 4. Return product.
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // 25.5.1 JSON.parse ( text [ , reviver ] ), https://tc39.es/ecma262/#sec-json.parse
@@ -410,7 +410,7 @@ JS_DEFINE_NATIVE_FUNCTION(JSONObject::parse)
 {
     auto& realm = *vm.current_realm();
 
-    auto string = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto string = TRY(vm.argument(0).to_byte_string(vm));
     auto reviver = vm.argument(1);
 
     auto json = JsonValue::from_string(string);
@@ -419,7 +419,7 @@ JS_DEFINE_NATIVE_FUNCTION(JSONObject::parse)
     Value unfiltered = parse_json_value(vm, json.value());
     if (reviver.is_function()) {
         auto root = Object::create(realm, realm.intrinsics().object_prototype());
-        auto root_name = DeprecatedString::empty();
+        auto root_name = ByteString::empty();
         MUST(root->create_data_property_or_throw(root_name, unfiltered));
         return internalize_json_property(vm, root, root_name, reviver.as_function());
     }
@@ -439,7 +439,7 @@ Value JSONObject::parse_json_value(VM& vm, JsonValue const& value)
     if (value.is_number())
         return Value(value.to_double(0));
     if (value.is_string())
-        return PrimitiveString::create(vm, value.to_deprecated_string());
+        return PrimitiveString::create(vm, value.to_byte_string());
     if (value.is_bool())
         return Value(static_cast<bool>(value.as_bool()));
     VERIFY_NOT_REACHED();
@@ -490,7 +490,7 @@ ThrowCompletionOr<Value> JSONObject::internalize_json_property(VM& vm, Object* h
         } else {
             auto property_list = TRY(value_object.enumerable_own_property_names(Object::PropertyKind::Key));
             for (auto& property_key : property_list)
-                TRY(process_property(property_key.as_string().deprecated_string()));
+                TRY(process_property(property_key.as_string().byte_string()));
         }
     }
 
diff --git a/Userland/Libraries/LibJS/Runtime/JSONObject.h b/Userland/Libraries/LibJS/Runtime/JSONObject.h
index 0306b66c329..a3cbc4482b7 100644
--- a/Userland/Libraries/LibJS/Runtime/JSONObject.h
+++ b/Userland/Libraries/LibJS/Runtime/JSONObject.h
@@ -20,7 +20,7 @@ public:
 
     // The base implementation of stringify is exposed because it is used by
     // test-js to communicate between the JS tests and the C++ test runner.
-    static ThrowCompletionOr<Optional<DeprecatedString>> stringify_impl(VM&, Value value, Value replacer, Value space);
+    static ThrowCompletionOr<Optional<ByteString>> stringify_impl(VM&, Value value, Value replacer, Value space);
 
     static Value parse_json_value(VM&, JsonValue const&);
 
@@ -30,16 +30,16 @@ private:
     struct StringifyState {
         GCPtr<FunctionObject> replacer_function;
         HashTable<GCPtr<Object>> seen_objects;
-        DeprecatedString indent { DeprecatedString::empty() };
-        DeprecatedString gap;
-        Optional<Vector<DeprecatedString>> property_list;
+        ByteString indent { ByteString::empty() };
+        ByteString gap;
+        Optional<Vector<ByteString>> property_list;
     };
 
     // Stringify helpers
-    static ThrowCompletionOr<Optional<DeprecatedString>> serialize_json_property(VM&, StringifyState&, PropertyKey const& key, Object* holder);
-    static ThrowCompletionOr<DeprecatedString> serialize_json_object(VM&, StringifyState&, Object&);
-    static ThrowCompletionOr<DeprecatedString> serialize_json_array(VM&, StringifyState&, Object&);
-    static DeprecatedString quote_json_string(DeprecatedString);
+    static ThrowCompletionOr<Optional<ByteString>> serialize_json_property(VM&, StringifyState&, PropertyKey const& key, Object* holder);
+    static ThrowCompletionOr<ByteString> serialize_json_object(VM&, StringifyState&, Object&);
+    static ThrowCompletionOr<ByteString> serialize_json_array(VM&, StringifyState&, Object&);
+    static ByteString quote_json_string(ByteString);
 
     // Parse helpers
     static Object* parse_json_object(VM&, JsonObject const&);
diff --git a/Userland/Libraries/LibJS/Runtime/MapConstructor.cpp b/Userland/Libraries/LibJS/Runtime/MapConstructor.cpp
index 70ac2052020..11d838beea8 100644
--- a/Userland/Libraries/LibJS/Runtime/MapConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/MapConstructor.cpp
@@ -60,7 +60,7 @@ ThrowCompletionOr<NonnullGCPtr<Object>> MapConstructor::construct(FunctionObject
 
     (void)TRY(get_iterator_values(vm, vm.argument(0), [&](Value iterator_value) -> Optional<Completion> {
         if (!iterator_value.is_object())
-            return vm.throw_completion<TypeError>(ErrorType::NotAnObject, DeprecatedString::formatted("Iterator value {}", iterator_value.to_string_without_side_effects()));
+            return vm.throw_completion<TypeError>(ErrorType::NotAnObject, ByteString::formatted("Iterator value {}", iterator_value.to_string_without_side_effects()));
 
         auto key = TRY(iterator_value.as_object().get(0));
         auto value = TRY(iterator_value.as_object().get(1));
diff --git a/Userland/Libraries/LibJS/Runtime/ModuleRequest.h b/Userland/Libraries/LibJS/Runtime/ModuleRequest.h
index 71735b3fba3..1f1f1d1834d 100644
--- a/Userland/Libraries/LibJS/Runtime/ModuleRequest.h
+++ b/Userland/Libraries/LibJS/Runtime/ModuleRequest.h
@@ -14,14 +14,14 @@
 namespace JS {
 
 struct ModuleWithSpecifier {
-    DeprecatedString specifier;  // [[Specifier]]
+    ByteString specifier;        // [[Specifier]]
     NonnullGCPtr<Module> module; // [[Module]]
 };
 
 // https://tc39.es/proposal-import-attributes/#importattribute-record
 struct ImportAttribute {
-    DeprecatedString key;
-    DeprecatedString value;
+    ByteString key;
+    ByteString value;
 };
 
 // https://tc39.es/proposal-import-attributes/#modulerequest-record
@@ -35,7 +35,7 @@ struct ModuleRequest {
 
     ModuleRequest(DeprecatedFlyString specifier, Vector<ImportAttribute> attributes);
 
-    void add_attribute(DeprecatedString key, DeprecatedString value)
+    void add_attribute(ByteString key, ByteString value)
     {
         attributes.empend(move(key), move(value));
     }
diff --git a/Userland/Libraries/LibJS/Runtime/NumberPrototype.cpp b/Userland/Libraries/LibJS/Runtime/NumberPrototype.cpp
index b216c02ca5f..dd06de327b1 100644
--- a/Userland/Libraries/LibJS/Runtime/NumberPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/NumberPrototype.cpp
@@ -92,7 +92,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_exponential)
 
     // 4. If x is not finite, return Number::toString(x).
     if (!number_value.is_finite_number())
-        return PrimitiveString::create(vm, MUST(number_value.to_deprecated_string(vm)));
+        return PrimitiveString::create(vm, MUST(number_value.to_byte_string(vm)));
 
     // 5. If f < 0 or f > 100, throw a RangeError exception.
     if (fraction_digits < 0 || fraction_digits > 100)
@@ -104,7 +104,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_exponential)
     // 7. Let s be the empty String.
     auto sign = ""sv;
 
-    DeprecatedString number_string;
+    ByteString number_string;
     int exponent = 0;
 
     // 8. If x < 0, then
@@ -119,7 +119,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_exponential)
     // 9. If x = 0, then
     if (number == 0) {
         // a. Let m be the String value consisting of f + 1 occurrences of the code unit 0x0030 (DIGIT ZERO).
-        number_string = DeprecatedString::repeated('0', fraction_digits + 1);
+        number_string = ByteString::repeated('0', fraction_digits + 1);
 
         // b. Let e be 0.
         exponent = 0;
@@ -147,7 +147,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_exponential)
         number = round(number / pow(10, exponent - fraction_digits));
 
         // c. Let m be the String value consisting of the digits of the decimal representation of n (in order, with no leading zeroes).
-        number_string = number_to_deprecated_string(number, NumberToStringMode::WithoutExponent);
+        number_string = number_to_byte_string(number, NumberToStringMode::WithoutExponent);
     }
 
     // 11. If f ≠ 0, then
@@ -159,11 +159,11 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_exponential)
         auto second = number_string.substring_view(1);
 
         // c. Set m to the string-concatenation of a, ".", and b.
-        number_string = DeprecatedString::formatted("{}.{}", first, second);
+        number_string = ByteString::formatted("{}.{}", first, second);
     }
 
     char exponent_sign = 0;
-    DeprecatedString exponent_string;
+    ByteString exponent_string;
 
     // 12. If e = 0, then
     if (exponent == 0) {
@@ -192,12 +192,12 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_exponential)
         }
 
         // c. Let d be the String value consisting of the digits of the decimal representation of e (in order, with no leading zeroes).
-        exponent_string = DeprecatedString::number(exponent);
+        exponent_string = ByteString::number(exponent);
     }
 
     // 14. Set m to the string-concatenation of m, "e", c, and d.
     // 15. Return the string-concatenation of s and m.
-    return PrimitiveString::create(vm, DeprecatedString::formatted("{}{}e{}{}", sign, number_string, exponent_sign, exponent_string));
+    return PrimitiveString::create(vm, ByteString::formatted("{}{}e{}{}", sign, number_string, exponent_sign, exponent_string));
 }
 
 // 21.1.3.3 Number.prototype.toFixed ( fractionDigits ), https://tc39.es/ecma262/#sec-number.prototype.tofixed
@@ -220,7 +220,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_fixed)
 
     // 6. If x is not finite, return Number::toString(x).
     if (!number_value.is_finite_number())
-        return PrimitiveString::create(vm, TRY(number_value.to_deprecated_string(vm)));
+        return PrimitiveString::create(vm, TRY(number_value.to_byte_string(vm)));
 
     // 7. Set x to ℝ(x).
     auto number = number_value.as_double();
@@ -236,7 +236,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_fixed)
     // 10. If x ≥ 10^21, then
     //     a. Let m be ! ToString(𝔽(x)).
     if (number >= 1e+21)
-        return PrimitiveString::create(vm, MUST(number_value.to_deprecated_string(vm)));
+        return PrimitiveString::create(vm, MUST(number_value.to_byte_string(vm)));
 
     // 11. Else,
     //     a. Let n be an integer for which n / (10^f) - x is as close to zero as possible. If there are two such n, pick the larger n.
@@ -256,8 +256,8 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_fixed)
     //       `number` double. Instead of generating a huge, unwieldy `n`, we format
     //       the double using our existing formatting code.
 
-    auto number_format_string = DeprecatedString::formatted("{{}}{{:.{}f}}", fraction_digits);
-    return PrimitiveString::create(vm, DeprecatedString::formatted(number_format_string, s, number));
+    auto number_format_string = ByteString::formatted("{{}}{{:.{}f}}", fraction_digits);
+    return PrimitiveString::create(vm, ByteString::formatted(number_format_string, s, number));
 }
 
 // 19.2.1 Number.prototype.toLocaleString ( [ locales [ , options ] ] ), https://tc39.es/ecma402/#sup-number.prototype.tolocalestring
@@ -289,14 +289,14 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_precision)
 
     // 2. If precision is undefined, return ! ToString(x).
     if (precision_value.is_undefined())
-        return PrimitiveString::create(vm, MUST(number_value.to_deprecated_string(vm)));
+        return PrimitiveString::create(vm, MUST(number_value.to_byte_string(vm)));
 
     // 3. Let p be ? ToIntegerOrInfinity(precision).
     auto precision = TRY(precision_value.to_integer_or_infinity(vm));
 
     // 4. If x is not finite, return Number::toString(x).
     if (!number_value.is_finite_number())
-        return PrimitiveString::create(vm, MUST(number_value.to_deprecated_string(vm)));
+        return PrimitiveString::create(vm, MUST(number_value.to_byte_string(vm)));
 
     // 5. If p < 1 or p > 100, throw a RangeError exception.
     if ((precision < 1) || (precision > 100))
@@ -308,7 +308,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_precision)
     // 7. Let s be the empty String.
     auto sign = ""sv;
 
-    DeprecatedString number_string;
+    ByteString number_string;
     int exponent = 0;
 
     // 8. If x < 0, then
@@ -323,7 +323,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_precision)
     // 9. If x = 0, then
     if (number == 0) {
         // a. Let m be the String value consisting of p occurrences of the code unit 0x0030 (DIGIT ZERO).
-        number_string = DeprecatedString::repeated('0', precision);
+        number_string = ByteString::repeated('0', precision);
 
         // b. Let e be 0.
         exponent = 0;
@@ -336,7 +336,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_precision)
         number = round(number / pow(10, exponent - precision + 1));
 
         // b. Let m be the String value consisting of the digits of the decimal representation of n (in order, with no leading zeroes).
-        number_string = number_to_deprecated_string(number, NumberToStringMode::WithoutExponent);
+        number_string = number_to_byte_string(number, NumberToStringMode::WithoutExponent);
 
         // c. If e < -6 or e ≥ p, then
         if ((exponent < -6) || (exponent >= precision)) {
@@ -352,7 +352,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_precision)
                 auto second = number_string.substring_view(1);
 
                 // 3. Set m to the string-concatenation of a, ".", and b.
-                number_string = DeprecatedString::formatted("{}.{}", first, second);
+                number_string = ByteString::formatted("{}.{}", first, second);
             }
 
             char exponent_sign = 0;
@@ -375,21 +375,21 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_precision)
             }
 
             // v. Let d be the String value consisting of the digits of the decimal representation of e (in order, with no leading zeroes).
-            auto exponent_string = DeprecatedString::number(exponent);
+            auto exponent_string = ByteString::number(exponent);
 
             // vi. Return the string-concatenation of s, m, the code unit 0x0065 (LATIN SMALL LETTER E), c, and d.
-            return PrimitiveString::create(vm, DeprecatedString::formatted("{}{}e{}{}", sign, number_string, exponent_sign, exponent_string));
+            return PrimitiveString::create(vm, ByteString::formatted("{}{}e{}{}", sign, number_string, exponent_sign, exponent_string));
         }
     }
 
     // 11. If e = p - 1, return the string-concatenation of s and m.
     if (exponent == precision - 1)
-        return PrimitiveString::create(vm, DeprecatedString::formatted("{}{}", sign, number_string));
+        return PrimitiveString::create(vm, ByteString::formatted("{}{}", sign, number_string));
 
     // 12. If e ≥ 0, then
     if (exponent >= 0) {
         // a. Set m to the string-concatenation of the first e + 1 code units of m, the code unit 0x002E (FULL STOP), and the remaining p - (e + 1) code units of m.
-        number_string = DeprecatedString::formatted(
+        number_string = ByteString::formatted(
             "{}.{}",
             number_string.substring_view(0, exponent + 1),
             number_string.substring_view(exponent + 1));
@@ -397,14 +397,14 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_precision)
     // 13. Else,
     else {
         // a. Set m to the string-concatenation of the code unit 0x0030 (DIGIT ZERO), the code unit 0x002E (FULL STOP), -(e + 1) occurrences of the code unit 0x0030 (DIGIT ZERO), and the String m.
-        number_string = DeprecatedString::formatted(
+        number_string = ByteString::formatted(
             "0.{}{}",
-            DeprecatedString::repeated('0', -1 * (exponent + 1)),
+            ByteString::repeated('0', -1 * (exponent + 1)),
             number_string);
     }
 
     // 14. Return the string-concatenation of s and m.
-    return PrimitiveString::create(vm, DeprecatedString::formatted("{}{}", sign, number_string));
+    return PrimitiveString::create(vm, ByteString::formatted("{}{}", sign, number_string));
 }
 
 // 21.1.3.6 Number.prototype.toString ( [ radix ] ), https://tc39.es/ecma262/#sec-number.prototype.tostring
@@ -428,7 +428,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_string)
 
     // 5. If radixMV = 10, return ! ToString(x).
     if (radix_mv == 10)
-        return PrimitiveString::create(vm, MUST(number_value.to_deprecated_string(vm)));
+        return PrimitiveString::create(vm, MUST(number_value.to_byte_string(vm)));
 
     // 6. Return the String representation of this Number value using the radix specified by radixMV. Letters a-z are used for digits with values 10 through 35. The precise algorithm is implementation-defined, however the algorithm should be a generalization of that specified in 6.1.6.1.20.
     if (number_value.is_positive_infinity())
@@ -487,7 +487,7 @@ JS_DEFINE_NATIVE_FUNCTION(NumberPrototype::to_string)
             characters.take_last();
     }
 
-    return PrimitiveString::create(vm, DeprecatedString(characters.data(), characters.size()));
+    return PrimitiveString::create(vm, ByteString(characters.data(), characters.size()));
 }
 
 // 21.1.3.7 Number.prototype.valueOf ( ), https://tc39.es/ecma262/#sec-number.prototype.valueof
diff --git a/Userland/Libraries/LibJS/Runtime/Object.cpp b/Userland/Libraries/LibJS/Runtime/Object.cpp
index bfef37348b1..eace11ef0e0 100644
--- a/Userland/Libraries/LibJS/Runtime/Object.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Object.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/TypeCasts.h>
 #include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/Accessor.h>
@@ -1042,7 +1042,7 @@ ThrowCompletionOr<MarkedVector<Value>> Object::internal_own_property_keys() cons
     // 2. For each own property key P of O such that P is an array index, in ascending numeric index order, do
     for (auto& entry : m_indexed_properties) {
         // a. Add P as the last element of keys.
-        keys.append(PrimitiveString::create(vm, DeprecatedString::number(entry.index())));
+        keys.append(PrimitiveString::create(vm, ByteString::number(entry.index())));
     }
 
     // 3. For each own property key P of O such that Type(P) is String and P is not an array index, in ascending chronological order of property creation, do
@@ -1347,7 +1347,7 @@ Optional<Completion> Object::enumerate_object_properties(Function<Optional<Compl
         for (auto& key : own_keys) {
             if (!key.is_string())
                 continue;
-            DeprecatedFlyString property_key = key.as_string().deprecated_string();
+            DeprecatedFlyString property_key = key.as_string().byte_string();
             if (visited.contains(property_key))
                 continue;
             auto descriptor = TRY(target->internal_get_own_property(property_key));
diff --git a/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp b/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp
index 4479b7273b1..f0adc944e91 100644
--- a/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ObjectConstructor.cpp
@@ -278,7 +278,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectConstructor::from_entries)
     // 6. Return ? AddEntriesFromIterable(obj, iterable, adder).
     (void)TRY(get_iterator_values(vm, iterable, [&](Value iterator_value) -> Optional<Completion> {
         if (!iterator_value.is_object())
-            return vm.throw_completion<TypeError>(ErrorType::NotAnObject, DeprecatedString::formatted("Iterator value {}", iterator_value.to_string_without_side_effects()));
+            return vm.throw_completion<TypeError>(ErrorType::NotAnObject, ByteString::formatted("Iterator value {}", iterator_value.to_string_without_side_effects()));
 
         auto key = TRY(iterator_value.as_object().get(0));
         auto value = TRY(iterator_value.as_object().get(1));
diff --git a/Userland/Libraries/LibJS/Runtime/ObjectPrototype.cpp b/Userland/Libraries/LibJS/Runtime/ObjectPrototype.cpp
index ffa394a06c5..e00f2c6e9a9 100644
--- a/Userland/Libraries/LibJS/Runtime/ObjectPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ObjectPrototype.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/Accessor.h>
@@ -147,7 +147,7 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectPrototype::to_string)
     // 4. Let isArray be ? IsArray(O).
     auto is_array = TRY(Value(object).is_array(vm));
 
-    DeprecatedString builtin_tag;
+    ByteString builtin_tag;
 
     // 5. If isArray is true, let builtinTag be "Array".
     if (is_array)
@@ -184,16 +184,16 @@ JS_DEFINE_NATIVE_FUNCTION(ObjectPrototype::to_string)
     auto to_string_tag = TRY(object->get(vm.well_known_symbol_to_string_tag()));
 
     // Optimization: Instead of creating another PrimitiveString from builtin_tag, we separate tag and to_string_tag and add an additional branch to step 16.
-    DeprecatedString tag;
+    ByteString tag;
 
     // 16. If Type(tag) is not String, set tag to builtinTag.
     if (!to_string_tag.is_string())
         tag = move(builtin_tag);
     else
-        tag = to_string_tag.as_string().deprecated_string();
+        tag = to_string_tag.as_string().byte_string();
 
     // 17. Return the string-concatenation of "[object ", tag, and "]".
-    return PrimitiveString::create(vm, DeprecatedString::formatted("[object {}]", tag));
+    return PrimitiveString::create(vm, ByteString::formatted("[object {}]", tag));
 }
 
 // 20.1.3.7 Object.prototype.valueOf ( ), https://tc39.es/ecma262/#sec-object.prototype.valueof
diff --git a/Userland/Libraries/LibJS/Runtime/PrimitiveString.cpp b/Userland/Libraries/LibJS/Runtime/PrimitiveString.cpp
index 577e08889e6..4095daab761 100644
--- a/Userland/Libraries/LibJS/Runtime/PrimitiveString.cpp
+++ b/Userland/Libraries/LibJS/Runtime/PrimitiveString.cpp
@@ -33,8 +33,8 @@ PrimitiveString::PrimitiveString(String string)
 {
 }
 
-PrimitiveString::PrimitiveString(DeprecatedString string)
-    : m_deprecated_string(move(string))
+PrimitiveString::PrimitiveString(ByteString string)
+    : m_byte_string(move(string))
 {
 }
 
@@ -47,8 +47,8 @@ PrimitiveString::~PrimitiveString()
 {
     if (has_utf8_string())
         vm().string_cache().remove(*m_utf8_string);
-    if (has_deprecated_string())
-        vm().deprecated_string_cache().remove(*m_deprecated_string);
+    if (has_byte_string())
+        vm().byte_string_cache().remove(*m_byte_string);
 }
 
 void PrimitiveString::visit_edges(Cell::Visitor& visitor)
@@ -71,8 +71,8 @@ bool PrimitiveString::is_empty() const
         return m_utf16_string->is_empty();
     if (has_utf8_string())
         return m_utf8_string->is_empty();
-    if (has_deprecated_string())
-        return m_deprecated_string->is_empty();
+    if (has_byte_string())
+        return m_byte_string->is_empty();
     VERIFY_NOT_REACHED();
 }
 
@@ -81,8 +81,8 @@ String PrimitiveString::utf8_string() const
     resolve_rope_if_needed(EncodingPreference::UTF8);
 
     if (!has_utf8_string()) {
-        if (has_deprecated_string())
-            m_utf8_string = MUST(String::from_deprecated_string(*m_deprecated_string));
+        if (has_byte_string())
+            m_utf8_string = MUST(String::from_byte_string(*m_byte_string));
         else if (has_utf16_string())
             m_utf8_string = m_utf16_string->to_utf8();
         else
@@ -98,20 +98,20 @@ StringView PrimitiveString::utf8_string_view() const
     return m_utf8_string->bytes_as_string_view();
 }
 
-DeprecatedString PrimitiveString::deprecated_string() const
+ByteString PrimitiveString::byte_string() const
 {
     resolve_rope_if_needed(EncodingPreference::UTF8);
 
-    if (!has_deprecated_string()) {
+    if (!has_byte_string()) {
         if (has_utf8_string())
-            m_deprecated_string = m_utf8_string->to_deprecated_string();
+            m_byte_string = m_utf8_string->to_byte_string();
         else if (has_utf16_string())
-            m_deprecated_string = m_utf16_string->to_deprecated_string();
+            m_byte_string = m_utf16_string->to_byte_string();
         else
             VERIFY_NOT_REACHED();
     }
 
-    return *m_deprecated_string;
+    return *m_byte_string;
 }
 
 Utf16String PrimitiveString::utf16_string() const
@@ -122,8 +122,8 @@ Utf16String PrimitiveString::utf16_string() const
         if (has_utf8_string()) {
             m_utf16_string = Utf16String::create(m_utf8_string->bytes_as_string_view());
         } else {
-            VERIFY(has_deprecated_string());
-            m_utf16_string = Utf16String::create(*m_deprecated_string);
+            VERIFY(has_byte_string());
+            m_utf16_string = Utf16String::create(*m_byte_string);
         }
     }
 
@@ -200,7 +200,7 @@ NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, StringView string)
     return create(vm, String::from_utf8(string).release_value());
 }
 
-NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, DeprecatedString string)
+NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, ByteString string)
 {
     if (string.is_empty())
         return vm.empty_string();
@@ -211,7 +211,7 @@ NonnullGCPtr<PrimitiveString> PrimitiveString::create(VM& vm, DeprecatedString s
             return vm.single_ascii_character_string(ch);
     }
 
-    auto& string_cache = vm.deprecated_string_cache();
+    auto& string_cache = vm.byte_string_cache();
     auto it = string_cache.find(string);
     if (it == string_cache.end()) {
         auto new_string = vm.heap().allocate_without_realm<PrimitiveString>(string);
diff --git a/Userland/Libraries/LibJS/Runtime/PrimitiveString.h b/Userland/Libraries/LibJS/Runtime/PrimitiveString.h
index 88f3c175d31..3519f1b0048 100644
--- a/Userland/Libraries/LibJS/Runtime/PrimitiveString.h
+++ b/Userland/Libraries/LibJS/Runtime/PrimitiveString.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <AK/String.h>
 #include <AK/StringView.h>
@@ -28,7 +28,7 @@ public:
     [[nodiscard]] static NonnullGCPtr<PrimitiveString> create(VM&, Utf16String);
     [[nodiscard]] static NonnullGCPtr<PrimitiveString> create(VM&, String);
     [[nodiscard]] static NonnullGCPtr<PrimitiveString> create(VM&, FlyString const&);
-    [[nodiscard]] static NonnullGCPtr<PrimitiveString> create(VM&, DeprecatedString);
+    [[nodiscard]] static NonnullGCPtr<PrimitiveString> create(VM&, ByteString);
     [[nodiscard]] static NonnullGCPtr<PrimitiveString> create(VM&, DeprecatedFlyString const&);
     [[nodiscard]] static NonnullGCPtr<PrimitiveString> create(VM&, PrimitiveString&, PrimitiveString&);
     [[nodiscard]] static NonnullGCPtr<PrimitiveString> create(VM&, StringView);
@@ -44,8 +44,8 @@ public:
     [[nodiscard]] StringView utf8_string_view() const;
     bool has_utf8_string() const { return m_utf8_string.has_value(); }
 
-    [[nodiscard]] DeprecatedString deprecated_string() const;
-    bool has_deprecated_string() const { return m_deprecated_string.has_value(); }
+    [[nodiscard]] ByteString byte_string() const;
+    bool has_byte_string() const { return m_byte_string.has_value(); }
 
     [[nodiscard]] Utf16String utf16_string() const;
     [[nodiscard]] Utf16View utf16_string_view() const;
@@ -56,7 +56,7 @@ public:
 private:
     explicit PrimitiveString(PrimitiveString&, PrimitiveString&);
     explicit PrimitiveString(String);
-    explicit PrimitiveString(DeprecatedString);
+    explicit PrimitiveString(ByteString);
     explicit PrimitiveString(Utf16String);
 
     virtual void visit_edges(Cell::Visitor&) override;
@@ -73,7 +73,7 @@ private:
     mutable GCPtr<PrimitiveString> m_rhs;
 
     mutable Optional<String> m_utf8_string;
-    mutable Optional<DeprecatedString> m_deprecated_string;
+    mutable Optional<ByteString> m_byte_string;
     mutable Optional<Utf16String> m_utf16_string;
 };
 
diff --git a/Userland/Libraries/LibJS/Runtime/PropertyAttributes.h b/Userland/Libraries/LibJS/Runtime/PropertyAttributes.h
index dd11fd96fa7..1ab8a251fbc 100644
--- a/Userland/Libraries/LibJS/Runtime/PropertyAttributes.h
+++ b/Userland/Libraries/LibJS/Runtime/PropertyAttributes.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/Types.h>
 #include <AK/Vector.h>
@@ -76,11 +76,11 @@ template<>
 struct Formatter<JS::PropertyAttributes> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, JS::PropertyAttributes const& property_attributes)
     {
-        Vector<DeprecatedString> parts;
-        parts.append(DeprecatedString::formatted("[[Writable]]: {}", property_attributes.is_writable()));
-        parts.append(DeprecatedString::formatted("[[Enumerable]]: {}", property_attributes.is_enumerable()));
-        parts.append(DeprecatedString::formatted("[[Configurable]]: {}", property_attributes.is_configurable()));
-        return Formatter<StringView>::format(builder, DeprecatedString::formatted("PropertyAttributes {{ {} }}", DeprecatedString::join(", "sv, parts)));
+        Vector<ByteString> parts;
+        parts.append(ByteString::formatted("[[Writable]]: {}", property_attributes.is_writable()));
+        parts.append(ByteString::formatted("[[Enumerable]]: {}", property_attributes.is_enumerable()));
+        parts.append(ByteString::formatted("[[Configurable]]: {}", property_attributes.is_configurable()));
+        return Formatter<StringView>::format(builder, ByteString::formatted("PropertyAttributes {{ {} }}", ByteString::join(", "sv, parts)));
     }
 };
 
diff --git a/Userland/Libraries/LibJS/Runtime/PropertyKey.h b/Userland/Libraries/LibJS/Runtime/PropertyKey.h
index 0d0203a908d..7645a45f995 100644
--- a/Userland/Libraries/LibJS/Runtime/PropertyKey.h
+++ b/Userland/Libraries/LibJS/Runtime/PropertyKey.h
@@ -35,7 +35,7 @@ public:
             return PropertyKey { value.as_symbol() };
         if (value.is_integral_number() && value.as_double() >= 0 && value.as_double() < NumericLimits<u32>::max())
             return static_cast<u32>(value.as_double());
-        return TRY(value.to_deprecated_string(vm));
+        return TRY(value.to_byte_string(vm));
     }
 
     PropertyKey() = default;
@@ -48,7 +48,7 @@ public:
         VERIFY(index >= 0);
         if constexpr (NumericLimits<T>::max() >= NumericLimits<u32>::max()) {
             if (index >= NumericLimits<u32>::max()) {
-                m_string = DeprecatedString::number(index);
+                m_string = ByteString::number(index);
                 m_type = Type::String;
                 m_string_may_be_number = false;
                 return;
@@ -65,7 +65,7 @@ public:
     {
     }
 
-    PropertyKey(DeprecatedString const& string)
+    PropertyKey(ByteString const& string)
         : m_type(Type::String)
         , m_string(DeprecatedFlyString(string))
     {
@@ -164,13 +164,13 @@ public:
         return m_symbol;
     }
 
-    DeprecatedString to_string() const
+    ByteString to_string() const
     {
         VERIFY(is_valid());
         VERIFY(!is_symbol());
         if (is_string())
             return as_string();
-        return DeprecatedString::number(as_number());
+        return ByteString::number(as_number());
     }
 
     StringOrSymbol to_string_or_symbol() const
diff --git a/Userland/Libraries/LibJS/Runtime/ProxyObject.cpp b/Userland/Libraries/LibJS/Runtime/ProxyObject.cpp
index 3e14b17cbed..1bcd9a4a4e4 100644
--- a/Userland/Libraries/LibJS/Runtime/ProxyObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ProxyObject.cpp
@@ -40,7 +40,7 @@ static Value property_key_to_value(VM& vm, PropertyKey const& property_key)
         return PrimitiveString::create(vm, property_key.as_string());
 
     VERIFY(property_key.is_number());
-    return PrimitiveString::create(vm, DeprecatedString::number(property_key.as_number()));
+    return PrimitiveString::create(vm, ByteString::number(property_key.as_number()));
 }
 
 // 10.5.1 [[GetPrototypeOf]] ( ), https://tc39.es/ecma262/#sec-proxy-object-internal-methods-and-internal-slots-getprototypeof
diff --git a/Userland/Libraries/LibJS/Runtime/RegExpObject.cpp b/Userland/Libraries/LibJS/Runtime/RegExpObject.cpp
index e86f9a1e270..6ea6e7b4bd8 100644
--- a/Userland/Libraries/LibJS/Runtime/RegExpObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/RegExpObject.cpp
@@ -18,7 +18,7 @@ namespace JS {
 
 JS_DEFINE_ALLOCATOR(RegExpObject);
 
-Result<regex::RegexOptions<ECMAScriptFlags>, DeprecatedString> regex_flags_from_string(StringView flags)
+Result<regex::RegexOptions<ECMAScriptFlags>, ByteString> regex_flags_from_string(StringView flags)
 {
     bool d = false, g = false, i = false, m = false, s = false, u = false, y = false, v = false;
     auto options = RegExpObject::default_flags;
@@ -27,42 +27,42 @@ Result<regex::RegexOptions<ECMAScriptFlags>, DeprecatedString> regex_flags_from_
         switch (ch) {
         case 'd':
             if (d)
-                return DeprecatedString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
+                return ByteString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
             d = true;
             break;
         case 'g':
             if (g)
-                return DeprecatedString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
+                return ByteString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
             g = true;
             options |= regex::ECMAScriptFlags::Global;
             break;
         case 'i':
             if (i)
-                return DeprecatedString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
+                return ByteString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
             i = true;
             options |= regex::ECMAScriptFlags::Insensitive;
             break;
         case 'm':
             if (m)
-                return DeprecatedString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
+                return ByteString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
             m = true;
             options |= regex::ECMAScriptFlags::Multiline;
             break;
         case 's':
             if (s)
-                return DeprecatedString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
+                return ByteString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
             s = true;
             options |= regex::ECMAScriptFlags::SingleLine;
             break;
         case 'u':
             if (u)
-                return DeprecatedString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
+                return ByteString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
             u = true;
             options |= regex::ECMAScriptFlags::Unicode;
             break;
         case 'y':
             if (y)
-                return DeprecatedString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
+                return ByteString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
             y = true;
             // Now for the more interesting flag, 'sticky' actually unsets 'global', part of which is the default.
             options.reset_flag(regex::ECMAScriptFlags::Global);
@@ -74,12 +74,12 @@ Result<regex::RegexOptions<ECMAScriptFlags>, DeprecatedString> regex_flags_from_
             break;
         case 'v':
             if (v)
-                return DeprecatedString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
+                return ByteString::formatted(ErrorType::RegExpObjectRepeatedFlag.message(), ch);
             v = true;
             options |= regex::ECMAScriptFlags::UnicodeSets;
             break;
         default:
-            return DeprecatedString::formatted(ErrorType::RegExpObjectBadFlag.message(), ch);
+            return ByteString::formatted(ErrorType::RegExpObjectBadFlag.message(), ch);
         }
     }
 
@@ -87,10 +87,10 @@ Result<regex::RegexOptions<ECMAScriptFlags>, DeprecatedString> regex_flags_from_
 }
 
 // 22.2.3.4 Static Semantics: ParsePattern ( patternText, u, v ), https://tc39.es/ecma262/#sec-parsepattern
-ErrorOr<DeprecatedString, ParseRegexPatternError> parse_regex_pattern(StringView pattern, bool unicode, bool unicode_sets)
+ErrorOr<ByteString, ParseRegexPatternError> parse_regex_pattern(StringView pattern, bool unicode, bool unicode_sets)
 {
     if (unicode && unicode_sets)
-        return ParseRegexPatternError { DeprecatedString::formatted(ErrorType::RegExpObjectIncompatibleFlags.message(), 'u', 'v') };
+        return ParseRegexPatternError { ByteString::formatted(ErrorType::RegExpObjectIncompatibleFlags.message(), 'u', 'v') };
 
     auto utf16_pattern_result = AK::utf8_to_utf16(pattern);
     if (utf16_pattern_result.is_error())
@@ -132,11 +132,11 @@ ErrorOr<DeprecatedString, ParseRegexPatternError> parse_regex_pattern(StringView
             previous_code_unit_was_backslash = false;
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // 22.2.3.4 Static Semantics: ParsePattern ( patternText, u, v ), https://tc39.es/ecma262/#sec-parsepattern
-ThrowCompletionOr<DeprecatedString> parse_regex_pattern(VM& vm, StringView pattern, bool unicode, bool unicode_sets)
+ThrowCompletionOr<ByteString> parse_regex_pattern(VM& vm, StringView pattern, bool unicode, bool unicode_sets)
 {
     auto result = parse_regex_pattern(pattern, unicode, unicode_sets);
     if (result.is_error())
@@ -150,7 +150,7 @@ NonnullGCPtr<RegExpObject> RegExpObject::create(Realm& realm)
     return realm.heap().allocate<RegExpObject>(realm, realm.intrinsics().regexp_prototype());
 }
 
-NonnullGCPtr<RegExpObject> RegExpObject::create(Realm& realm, Regex<ECMA262> regex, DeprecatedString pattern, DeprecatedString flags)
+NonnullGCPtr<RegExpObject> RegExpObject::create(Realm& realm, Regex<ECMA262> regex, ByteString pattern, ByteString flags)
 {
     return realm.heap().allocate<RegExpObject>(realm, move(regex), move(pattern), move(flags), realm.intrinsics().regexp_prototype());
 }
@@ -160,7 +160,7 @@ RegExpObject::RegExpObject(Object& prototype)
 {
 }
 
-RegExpObject::RegExpObject(Regex<ECMA262> regex, DeprecatedString pattern, DeprecatedString flags, Object& prototype)
+RegExpObject::RegExpObject(Regex<ECMA262> regex, ByteString pattern, ByteString flags, Object& prototype)
     : Object(ConstructWithPrototypeTag::Tag, prototype)
     , m_pattern(move(pattern))
     , m_flags(move(flags))
@@ -183,14 +183,14 @@ ThrowCompletionOr<NonnullGCPtr<RegExpObject>> RegExpObject::regexp_initialize(VM
     // 1. If pattern is undefined, let P be the empty String.
     // 2. Else, let P be ? ToString(pattern).
     auto pattern = pattern_value.is_undefined()
-        ? DeprecatedString::empty()
-        : TRY(pattern_value.to_deprecated_string(vm));
+        ? ByteString::empty()
+        : TRY(pattern_value.to_byte_string(vm));
 
     // 3. If flags is undefined, let F be the empty String.
     // 4. Else, let F be ? ToString(flags).
     auto flags = flags_value.is_undefined()
-        ? DeprecatedString::empty()
-        : TRY(flags_value.to_deprecated_string(vm));
+        ? ByteString::empty()
+        : TRY(flags_value.to_byte_string(vm));
 
     // 5. If F contains any code unit other than "d", "g", "i", "m", "s", "u", "v", or "y", or if F contains any code unit more than once, throw a SyntaxError exception.
     // 6. If F contains "i", let i be true; else let i be false.
@@ -203,7 +203,7 @@ ThrowCompletionOr<NonnullGCPtr<RegExpObject>> RegExpObject::regexp_initialize(VM
         return vm.throw_completion<SyntaxError>(parsed_flags_or_error.release_error());
     auto parsed_flags = parsed_flags_or_error.release_value();
 
-    auto parsed_pattern = DeprecatedString::empty();
+    auto parsed_pattern = ByteString::empty();
     if (!pattern.is_empty()) {
         bool unicode = parsed_flags.has_flag_set(regex::ECMAScriptFlags::Unicode);
         bool unicode_sets = parsed_flags.has_flag_set(regex::ECMAScriptFlags::UnicodeSets);
@@ -244,7 +244,7 @@ ThrowCompletionOr<NonnullGCPtr<RegExpObject>> RegExpObject::regexp_initialize(VM
 }
 
 // 22.2.6.13.1 EscapeRegExpPattern ( P, F ), https://tc39.es/ecma262/#sec-escaperegexppattern
-DeprecatedString RegExpObject::escape_regexp_pattern() const
+ByteString RegExpObject::escape_regexp_pattern() const
 {
     // 1. Let S be a String in the form of a Pattern[~UnicodeMode] (Pattern[+UnicodeMode] if F contains "u") equivalent
     //    to P interpreted as UTF-16 encoded Unicode code points (6.1.4), in which certain code points are escaped as
@@ -301,7 +301,7 @@ DeprecatedString RegExpObject::escape_regexp_pattern() const
         }
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // 22.2.3.1 RegExpCreate ( P, F ), https://tc39.es/ecma262/#sec-regexpcreate
diff --git a/Userland/Libraries/LibJS/Runtime/RegExpObject.h b/Userland/Libraries/LibJS/Runtime/RegExpObject.h
index 3dacd0b68eb..2ea9074ceb1 100644
--- a/Userland/Libraries/LibJS/Runtime/RegExpObject.h
+++ b/Userland/Libraries/LibJS/Runtime/RegExpObject.h
@@ -16,12 +16,12 @@ namespace JS {
 ThrowCompletionOr<NonnullGCPtr<RegExpObject>> regexp_create(VM&, Value pattern, Value flags);
 ThrowCompletionOr<NonnullGCPtr<RegExpObject>> regexp_alloc(VM&, FunctionObject& new_target);
 
-Result<regex::RegexOptions<ECMAScriptFlags>, DeprecatedString> regex_flags_from_string(StringView flags);
+Result<regex::RegexOptions<ECMAScriptFlags>, ByteString> regex_flags_from_string(StringView flags);
 struct ParseRegexPatternError {
-    DeprecatedString error;
+    ByteString error;
 };
-ErrorOr<DeprecatedString, ParseRegexPatternError> parse_regex_pattern(StringView pattern, bool unicode, bool unicode_sets);
-ThrowCompletionOr<DeprecatedString> parse_regex_pattern(VM& vm, StringView pattern, bool unicode, bool unicode_sets);
+ErrorOr<ByteString, ParseRegexPatternError> parse_regex_pattern(StringView pattern, bool unicode, bool unicode_sets);
+ThrowCompletionOr<ByteString> parse_regex_pattern(VM& vm, StringView pattern, bool unicode, bool unicode_sets);
 
 class RegExpObject : public Object {
     JS_OBJECT(RegExpObject, Object);
@@ -38,16 +38,16 @@ public:
     };
 
     static NonnullGCPtr<RegExpObject> create(Realm&);
-    static NonnullGCPtr<RegExpObject> create(Realm&, Regex<ECMA262> regex, DeprecatedString pattern, DeprecatedString flags);
+    static NonnullGCPtr<RegExpObject> create(Realm&, Regex<ECMA262> regex, ByteString pattern, ByteString flags);
 
     ThrowCompletionOr<NonnullGCPtr<RegExpObject>> regexp_initialize(VM&, Value pattern, Value flags);
-    DeprecatedString escape_regexp_pattern() const;
+    ByteString escape_regexp_pattern() const;
 
     virtual void initialize(Realm&) override;
     virtual ~RegExpObject() override = default;
 
-    DeprecatedString const& pattern() const { return m_pattern; }
-    DeprecatedString const& flags() const { return m_flags; }
+    ByteString const& pattern() const { return m_pattern; }
+    ByteString const& flags() const { return m_flags; }
     Regex<ECMA262> const& regex() { return *m_regex; }
     Regex<ECMA262> const& regex() const { return *m_regex; }
     Realm& realm() { return *m_realm; }
@@ -58,10 +58,10 @@ public:
 
 private:
     RegExpObject(Object& prototype);
-    RegExpObject(Regex<ECMA262> regex, DeprecatedString pattern, DeprecatedString flags, Object& prototype);
+    RegExpObject(Regex<ECMA262> regex, ByteString pattern, ByteString flags, Object& prototype);
 
-    DeprecatedString m_pattern;
-    DeprecatedString m_flags;
+    ByteString m_pattern;
+    ByteString m_flags;
     bool m_legacy_features_enabled { false }; // [[LegacyFeaturesEnabled]]
     // Note: This is initialized in RegExpAlloc, but will be non-null afterwards
     GCPtr<Realm> m_realm; // [[Realm]]
diff --git a/Userland/Libraries/LibJS/Runtime/RegExpPrototype.cpp b/Userland/Libraries/LibJS/Runtime/RegExpPrototype.cpp
index 096e1fb536f..82ce3c09596 100644
--- a/Userland/Libraries/LibJS/Runtime/RegExpPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/RegExpPrototype.cpp
@@ -513,7 +513,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::flags)
 #undef __JS_ENUMERATE
 
     // 20. Return result.
-    return PrimitiveString::create(vm, builder.to_deprecated_string());
+    return PrimitiveString::create(vm, builder.to_byte_string());
 }
 
 // 22.2.6.8 RegExp.prototype [ @@match ] ( string ), https://tc39.es/ecma262/#sec-regexp.prototype-@@match
@@ -530,7 +530,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::symbol_match)
 
     // 4. Let flags be ? ToString(? Get(rx, "flags")).
     auto flags_value = TRY(regexp_object->get(vm.names.flags));
-    auto flags = TRY(flags_value.to_deprecated_string(vm));
+    auto flags = TRY(flags_value.to_byte_string(vm));
 
     // 5. If flags does not contain "g", then
     if (!flags.contains('g')) {
@@ -573,7 +573,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::symbol_match)
 
         // 1. Let matchStr be ? ToString(? Get(result, "0")).
         auto match_value = TRY(result.get(0));
-        auto match_str = TRY(match_value.to_deprecated_string(vm));
+        auto match_str = TRY(match_value.to_byte_string(vm));
 
         // 2. Perform ! CreateDataPropertyOrThrow(A, ! ToString(𝔽(n)), matchStr).
         MUST(array->create_data_property_or_throw(n, PrimitiveString::create(vm, match_str)));
@@ -606,7 +606,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::symbol_match_all)
 
     // 5. Let flags be ? ToString(? Get(R, "flags")).
     auto flags_value = TRY(regexp_object->get(vm.names.flags));
-    auto flags = TRY(flags_value.to_deprecated_string(vm));
+    auto flags = TRY(flags_value.to_byte_string(vm));
 
     // Steps 9-12 are performed early so that flags can be moved.
 
@@ -651,13 +651,13 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::symbol_replace)
     // 6. If functionalReplace is false, then
     if (!replace_value.is_function()) {
         // a. Set replaceValue to ? ToString(replaceValue).
-        auto replace_string = TRY(replace_value.to_deprecated_string(vm));
+        auto replace_string = TRY(replace_value.to_byte_string(vm));
         replace_value = PrimitiveString::create(vm, move(replace_string));
     }
 
     // 7. Let flags be ? ToString(? Get(rx, "flags")).
     auto flags_value = TRY(regexp_object->get(vm.names.flags));
-    auto flags = TRY(flags_value.to_deprecated_string(vm));
+    auto flags = TRY(flags_value.to_byte_string(vm));
 
     // 8. If flags contains "g", let global be true. Otherwise, let global be false.
     bool global = flags.contains('g');
@@ -694,7 +694,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::symbol_replace)
 
         // 1. Let matchStr be ? ToString(? Get(result, "0")).
         auto match_value = TRY(result.get(vm, 0));
-        auto match_str = TRY(match_value.to_deprecated_string(vm));
+        auto match_str = TRY(match_value.to_byte_string(vm));
 
         // 2. If matchStr is the empty String, then
         if (match_str.is_empty()) {
@@ -746,7 +746,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::symbol_replace)
             // ii. If capN is not undefined, then
             if (!capture.is_undefined()) {
                 // 1. Set capN to ? ToString(capN).
-                capture = PrimitiveString::create(vm, TRY(capture.to_deprecated_string(vm)));
+                capture = PrimitiveString::create(vm, TRY(capture.to_byte_string(vm)));
             }
 
             // iii. Append capN as the last element of captures.
@@ -810,13 +810,13 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::symbol_replace)
 
     // 16. If nextSourcePosition ≥ lengthS, return accumulatedResult.
     if (next_source_position >= string.length_in_code_units())
-        return PrimitiveString::create(vm, accumulated_result.to_deprecated_string());
+        return PrimitiveString::create(vm, accumulated_result.to_byte_string());
 
     // 17. Return the string-concatenation of accumulatedResult and the substring of S from nextSourcePosition.
     auto substring = string.substring_view(next_source_position);
     accumulated_result.append(substring);
 
-    return PrimitiveString::create(vm, accumulated_result.to_deprecated_string());
+    return PrimitiveString::create(vm, accumulated_result.to_byte_string());
 }
 
 // 22.2.6.12 RegExp.prototype [ @@search ] ( string ), https://tc39.es/ecma262/#sec-regexp.prototype-@@search
@@ -901,7 +901,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::symbol_split)
 
     // 5. Let flags be ? ToString(? Get(rx, "flags")).
     auto flags_value = TRY(regexp_object->get(vm.names.flags));
-    auto flags = TRY(flags_value.to_deprecated_string(vm));
+    auto flags = TRY(flags_value.to_byte_string(vm));
 
     // 6. If flags contains "u" or flags contains "v", let unicodeMatching be true.
     // 7. Else, let unicodeMatching be false.
@@ -909,7 +909,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::symbol_split)
 
     // 8. If flags contains "y", let newFlags be flags.
     // 9. Else, let newFlags be the string-concatenation of flags and "y".
-    auto new_flags = flags.find('y').has_value() ? move(flags) : DeprecatedString::formatted("{}y", flags);
+    auto new_flags = flags.find('y').has_value() ? move(flags) : ByteString::formatted("{}y", flags);
 
     // 10. Let splitter be ? Construct(C, « rx, newFlags »).
     auto splitter = TRY(construct(vm, *constructor, regexp_object, PrimitiveString::create(vm, move(new_flags))));
@@ -1066,15 +1066,15 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpPrototype::to_string)
 
     // 3. Let pattern be ? ToString(? Get(R, "source")).
     auto source_attr = TRY(regexp_object->get(vm.names.source));
-    auto pattern = TRY(source_attr.to_deprecated_string(vm));
+    auto pattern = TRY(source_attr.to_byte_string(vm));
 
     // 4. Let flags be ? ToString(? Get(R, "flags")).
     auto flags_attr = TRY(regexp_object->get(vm.names.flags));
-    auto flags = TRY(flags_attr.to_deprecated_string(vm));
+    auto flags = TRY(flags_attr.to_byte_string(vm));
 
     // 5. Let result be the string-concatenation of "/", pattern, "/", and flags.
     // 6. Return result.
-    return PrimitiveString::create(vm, DeprecatedString::formatted("/{}/{}", pattern, flags));
+    return PrimitiveString::create(vm, ByteString::formatted("/{}/{}", pattern, flags));
 }
 
 // B.2.4.1 RegExp.prototype.compile ( pattern, flags ), https://tc39.es/ecma262/#sec-regexp.prototype.compile
diff --git a/Userland/Libraries/LibJS/Runtime/RegExpStringIteratorPrototype.cpp b/Userland/Libraries/LibJS/Runtime/RegExpStringIteratorPrototype.cpp
index 58bb744a075..c3330b89f9e 100644
--- a/Userland/Libraries/LibJS/Runtime/RegExpStringIteratorPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/RegExpStringIteratorPrototype.cpp
@@ -53,7 +53,7 @@ JS_DEFINE_NATIVE_FUNCTION(RegExpStringIteratorPrototype::next)
 
     auto match_object = TRY(match.to_object(vm));
     auto match_string_value = TRY(match_object->get(0));
-    auto match_string = TRY(match_string_value.to_deprecated_string(vm));
+    auto match_string = TRY(match_string_value.to_byte_string(vm));
     if (match_string.is_empty()) {
         auto last_index_value = TRY(iterator->regexp_object().get(vm.names.lastIndex));
         auto last_index = TRY(last_index_value.to_length(vm));
diff --git a/Userland/Libraries/LibJS/Runtime/ShadowRealm.cpp b/Userland/Libraries/LibJS/Runtime/ShadowRealm.cpp
index 68ed68a1a61..007301a15b7 100644
--- a/Userland/Libraries/LibJS/Runtime/ShadowRealm.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ShadowRealm.cpp
@@ -89,7 +89,7 @@ ThrowCompletionOr<void> copy_name_and_length(VM& vm, FunctionObject& function, F
         target_name = PrimitiveString::create(vm, String {});
 
     // 8. Perform SetFunctionName(F, targetName, prefix).
-    function.set_function_name({ target_name.as_string().deprecated_string() }, move(prefix));
+    function.set_function_name({ target_name.as_string().byte_string() }, move(prefix));
 
     return {};
 }
@@ -214,7 +214,7 @@ ThrowCompletionOr<Value> perform_shadow_realm_eval(VM& vm, StringView source_tex
 }
 
 // 3.1.4 ShadowRealmImportValue ( specifierString: a String, exportNameString: a String, callerRealm: a Realm Record, evalRealm: a Realm Record, evalContext: an execution context, ), https://tc39.es/proposal-shadowrealm/#sec-shadowrealmimportvalue
-ThrowCompletionOr<Value> shadow_realm_import_value(VM& vm, DeprecatedString specifier_string, DeprecatedString export_name_string, Realm& caller_realm, Realm& eval_realm, ExecutionContext& eval_context)
+ThrowCompletionOr<Value> shadow_realm_import_value(VM& vm, ByteString specifier_string, ByteString export_name_string, Realm& caller_realm, Realm& eval_realm, ExecutionContext& eval_context)
 {
     // FIXME: evalRealm isn't being used anywhere in this AO (spec issue)
     (void)eval_realm;
diff --git a/Userland/Libraries/LibJS/Runtime/ShadowRealm.h b/Userland/Libraries/LibJS/Runtime/ShadowRealm.h
index 777a5a1489a..b183e81e0d3 100644
--- a/Userland/Libraries/LibJS/Runtime/ShadowRealm.h
+++ b/Userland/Libraries/LibJS/Runtime/ShadowRealm.h
@@ -37,7 +37,7 @@ private:
 
 ThrowCompletionOr<void> copy_name_and_length(VM&, FunctionObject& function, FunctionObject& target, Optional<StringView> prefix = {}, Optional<unsigned> arg_count = {});
 ThrowCompletionOr<Value> perform_shadow_realm_eval(VM&, StringView source_text, Realm& caller_realm, Realm& eval_realm);
-ThrowCompletionOr<Value> shadow_realm_import_value(VM&, DeprecatedString specifier_string, DeprecatedString export_name_string, Realm& caller_realm, Realm& eval_realm, ExecutionContext& eval_context);
+ThrowCompletionOr<Value> shadow_realm_import_value(VM&, ByteString specifier_string, ByteString export_name_string, Realm& caller_realm, Realm& eval_realm, ExecutionContext& eval_context);
 ThrowCompletionOr<Value> get_wrapped_value(VM&, Realm& caller_realm, Value);
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/ShadowRealmPrototype.cpp b/Userland/Libraries/LibJS/Runtime/ShadowRealmPrototype.cpp
index de7285c02ee..86d46a284f0 100644
--- a/Userland/Libraries/LibJS/Runtime/ShadowRealmPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ShadowRealmPrototype.cpp
@@ -51,7 +51,7 @@ JS_DEFINE_NATIVE_FUNCTION(ShadowRealmPrototype::evaluate)
     auto& eval_realm = object->shadow_realm();
 
     // 6. Return ? PerformShadowRealmEval(sourceText, callerRealm, evalRealm).
-    return perform_shadow_realm_eval(vm, source_text.as_string().deprecated_string(), *caller_realm, eval_realm);
+    return perform_shadow_realm_eval(vm, source_text.as_string().byte_string(), *caller_realm, eval_realm);
 }
 
 // 3.4.2 ShadowRealm.prototype.importValue ( specifier, exportName ), https://tc39.es/proposal-shadowrealm/#sec-shadowrealm.prototype.importvalue
@@ -65,7 +65,7 @@ JS_DEFINE_NATIVE_FUNCTION(ShadowRealmPrototype::import_value)
     auto object = TRY(typed_this_object(vm));
 
     // 3. Let specifierString be ? ToString(specifier).
-    auto specifier_string = TRY(specifier.to_deprecated_string(vm));
+    auto specifier_string = TRY(specifier.to_byte_string(vm));
 
     // 4. If Type(exportName) is not String, throw a TypeError exception.
     if (!export_name.is_string())
@@ -81,7 +81,7 @@ JS_DEFINE_NATIVE_FUNCTION(ShadowRealmPrototype::import_value)
     auto& eval_context = object->execution_context();
 
     // 8. Return ? ShadowRealmImportValue(specifierString, exportNameString, callerRealm, evalRealm, evalContext).
-    return shadow_realm_import_value(vm, move(specifier_string), export_name.as_string().deprecated_string(), *caller_realm, eval_realm, eval_context);
+    return shadow_realm_import_value(vm, move(specifier_string), export_name.as_string().byte_string(), *caller_realm, eval_realm, eval_context);
 }
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/StringConstructor.cpp b/Userland/Libraries/LibJS/Runtime/StringConstructor.cpp
index af5b2cec105..ce6f376e23b 100644
--- a/Userland/Libraries/LibJS/Runtime/StringConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/StringConstructor.cpp
@@ -167,13 +167,13 @@ JS_DEFINE_NATIVE_FUNCTION(StringConstructor::raw)
     // 7. Let nextIndex be 0.
     // 8. Repeat,
     for (size_t i = 0; i < literal_count; ++i) {
-        auto next_key = DeprecatedString::number(i);
+        auto next_key = ByteString::number(i);
 
         // a. Let nextLiteralVal be ? Get(literals, ! ToString(𝔽(nextIndex))).
         auto next_literal_value = TRY(literals->get(next_key));
 
         // b. Let nextLiteral be ? ToString(nextLiteralVal).
-        auto next_literal = TRY(next_literal_value.to_deprecated_string(vm));
+        auto next_literal = TRY(next_literal_value.to_byte_string(vm));
 
         // c. Set R to the string-concatenation of R and nextLiteral.
         builder.append(next_literal);
@@ -188,7 +188,7 @@ JS_DEFINE_NATIVE_FUNCTION(StringConstructor::raw)
             auto next_substitution_value = vm.argument(i + 1);
 
             // ii. Let nextSub be ? ToString(nextSubVal).
-            auto next_substitution = TRY(next_substitution_value.to_deprecated_string(vm));
+            auto next_substitution = TRY(next_substitution_value.to_byte_string(vm));
 
             // iii. Set R to the string-concatenation of R and nextSub.
             builder.append(next_substitution);
@@ -196,7 +196,7 @@ JS_DEFINE_NATIVE_FUNCTION(StringConstructor::raw)
 
         // f. Set nextIndex to nextIndex + 1.
     }
-    return PrimitiveString::create(vm, builder.to_deprecated_string());
+    return PrimitiveString::create(vm, builder.to_byte_string());
 }
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/StringOrSymbol.h b/Userland/Libraries/LibJS/Runtime/StringOrSymbol.h
index 9d5037d8770..d2d23aa999e 100644
--- a/Userland/Libraries/LibJS/Runtime/StringOrSymbol.h
+++ b/Userland/Libraries/LibJS/Runtime/StringOrSymbol.h
@@ -22,7 +22,7 @@ public:
     {
     }
 
-    StringOrSymbol(DeprecatedString const& string)
+    StringOrSymbol(ByteString const& string)
         : StringOrSymbol(DeprecatedFlyString(string))
     {
     }
@@ -74,12 +74,12 @@ public:
         return reinterpret_cast<Symbol const*>(bits() & ~1ul);
     }
 
-    DeprecatedString to_display_string() const
+    ByteString to_display_string() const
     {
         if (is_string())
             return as_string();
         if (is_symbol())
-            return as_symbol()->descriptive_string().release_value_but_fixme_should_propagate_errors().to_deprecated_string();
+            return as_symbol()->descriptive_string().release_value_but_fixme_should_propagate_errors().to_byte_string();
         VERIFY_NOT_REACHED();
     }
 
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp
index e22d38a9c08..e6adb2bd54b 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp
@@ -527,7 +527,7 @@ ThrowCompletionOr<Optional<String>> get_temporal_unit(VM& vm, Object const& norm
 
     // 10. If value is undefined and default is required, throw a RangeError exception.
     if (option_value.is_undefined() && default_.has<TemporalUnitRequired>())
-        return vm.throw_completion<RangeError>(ErrorType::IsUndefined, DeprecatedString::formatted("{} option value", key.as_string()));
+        return vm.throw_completion<RangeError>(ErrorType::IsUndefined, ByteString::formatted("{} option value", key.as_string()));
 
     auto value = option_value.is_undefined()
         ? Optional<String> {}
@@ -1794,7 +1794,7 @@ ThrowCompletionOr<Object*> prepare_temporal_fields(VM& vm, Object const& fields,
     // 3. For each value property of fieldNames, do
     for (auto& property : field_names) {
         // a. Let value be ? Get(fields, property).
-        auto value = TRY(fields.get(property.to_deprecated_string()));
+        auto value = TRY(fields.get(property.to_byte_string()));
 
         // b. If value is not undefined, then
         if (!value.is_undefined()) {
@@ -1823,7 +1823,7 @@ ThrowCompletionOr<Object*> prepare_temporal_fields(VM& vm, Object const& fields,
             }
 
             // iii. Perform ! CreateDataPropertyOrThrow(result, property, value).
-            MUST(result->create_data_property_or_throw(property.to_deprecated_string(), value));
+            MUST(result->create_data_property_or_throw(property.to_byte_string(), value));
         }
         // c. Else if requiredFields is a List, then
         else if (required_fields.has<Vector<StringView>>()) {
@@ -1840,7 +1840,7 @@ ThrowCompletionOr<Object*> prepare_temporal_fields(VM& vm, Object const& fields,
             }
 
             // iii. Perform ! CreateDataPropertyOrThrow(result, property, value).
-            MUST(result->create_data_property_or_throw(property.to_deprecated_string(), value));
+            MUST(result->create_data_property_or_throw(property.to_byte_string(), value));
         }
     }
 
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
index a517b02b7bb..1f2be4a6a63 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
@@ -787,7 +787,7 @@ ThrowCompletionOr<double> resolve_iso_month(VM& vm, Object const& fields)
 
     // 6. Assert: Type(monthCode) is String.
     VERIFY(month_code.is_string());
-    auto month_code_string = month_code.as_string().deprecated_string();
+    auto month_code_string = month_code.as_string().byte_string();
 
     // 7. If the length of monthCode is not 3, throw a RangeError exception.
     auto month_length = month_code_string.length();
@@ -963,7 +963,7 @@ ThrowCompletionOr<Object*> default_merge_calendar_fields(VM& vm, Object const& f
     // 3. For each element key of fieldsKeys, do
     for (auto& key : fields_keys) {
         // a. If key is not "month" or "monthCode", then
-        if (!key.as_string().deprecated_string().is_one_of(vm.names.month.as_string(), vm.names.monthCode.as_string())) {
+        if (!key.as_string().byte_string().is_one_of(vm.names.month.as_string(), vm.names.monthCode.as_string())) {
             auto property_key = MUST(PropertyKey::from_value(vm, key));
 
             // i. Let propValue be ? Get(fields, key).
@@ -997,7 +997,7 @@ ThrowCompletionOr<Object*> default_merge_calendar_fields(VM& vm, Object const& f
         }
 
         // See comment above.
-        additional_fields_keys_contains_month_or_month_code_property |= key.as_string().deprecated_string() == vm.names.month.as_string() || key.as_string().deprecated_string() == vm.names.monthCode.as_string();
+        additional_fields_keys_contains_month_or_month_code_property |= key.as_string().byte_string() == vm.names.month.as_string() || key.as_string().byte_string() == vm.names.monthCode.as_string();
     }
 
     // 6. If additionalFieldsKeys does not contain either "month" or "monthCode", then
diff --git a/Userland/Libraries/LibJS/Runtime/TypedArray.h b/Userland/Libraries/LibJS/Runtime/TypedArray.h
index 76d7a0c7b54..4aed96a29e4 100644
--- a/Userland/Libraries/LibJS/Runtime/TypedArray.h
+++ b/Userland/Libraries/LibJS/Runtime/TypedArray.h
@@ -402,7 +402,7 @@ public:
             // a. For each integer i starting with 0 such that i < O.[[ArrayLength]], in ascending order, do
             for (size_t i = 0; i < m_array_length; ++i) {
                 // i. Add ! ToString(𝔽(i)) as the last element of keys.
-                keys.append(PrimitiveString::create(vm, DeprecatedString::number(i)));
+                keys.append(PrimitiveString::create(vm, ByteString::number(i)));
             }
         }
 
diff --git a/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp b/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp
index f0a5979aade..ab5b7b148d5 100644
--- a/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/TypedArrayPrototype.cpp
@@ -90,7 +90,7 @@ static ThrowCompletionOr<TypedArrayBase*> validate_typed_array_from_this(VM& vm)
     return typed_array;
 }
 
-static ThrowCompletionOr<FunctionObject*> callback_from_args(VM& vm, DeprecatedString const& name)
+static ThrowCompletionOr<FunctionObject*> callback_from_args(VM& vm, ByteString const& name)
 {
     if (vm.argument_count() < 1)
         return vm.throw_completion<TypeError>(ErrorType::TypedArrayPrototypeOneArg, name);
@@ -100,7 +100,7 @@ static ThrowCompletionOr<FunctionObject*> callback_from_args(VM& vm, DeprecatedS
     return &callback.as_function();
 }
 
-static ThrowCompletionOr<void> for_each_item(VM& vm, DeprecatedString const& name, Function<IterationDecision(size_t index, Value value, Value callback_result)> callback)
+static ThrowCompletionOr<void> for_each_item(VM& vm, ByteString const& name, Function<IterationDecision(size_t index, Value value, Value callback_result)> callback)
 {
     auto* typed_array = TRY(validate_typed_array_from_this(vm));
 
@@ -122,7 +122,7 @@ static ThrowCompletionOr<void> for_each_item(VM& vm, DeprecatedString const& nam
     return {};
 }
 
-static ThrowCompletionOr<void> for_each_item_from_last(VM& vm, DeprecatedString const& name, Function<IterationDecision(size_t index, Value value, Value callback_result)> callback)
+static ThrowCompletionOr<void> for_each_item_from_last(VM& vm, ByteString const& name, Function<IterationDecision(size_t index, Value value, Value callback_result)> callback)
 {
     auto* typed_array = TRY(validate_typed_array_from_this(vm));
 
@@ -803,9 +803,9 @@ JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::join)
 
     // 4. If separator is undefined, let sep be ",".
     // 5. Else, let sep be ? ToString(separator).
-    DeprecatedString separator = ",";
+    ByteString separator = ",";
     if (!vm.argument(0).is_undefined())
-        separator = TRY(vm.argument(0).to_deprecated_string(vm));
+        separator = TRY(vm.argument(0).to_byte_string(vm));
 
     // 6. Let R be the empty String.
     StringBuilder builder;
@@ -823,7 +823,7 @@ JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::join)
         // c. If element is undefined, let next be the empty String; otherwise, let next be ! ToString(element).
         if (element.is_undefined())
             continue;
-        auto next = MUST(element.to_deprecated_string(vm));
+        auto next = MUST(element.to_byte_string(vm));
 
         // d. Set R to the string-concatenation of R and next.
         builder.append(next);
@@ -832,7 +832,7 @@ JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::join)
     }
 
     // 9. Return R.
-    return PrimitiveString::create(vm, builder.to_deprecated_string());
+    return PrimitiveString::create(vm, builder.to_byte_string());
 }
 
 // 23.2.3.19 %TypedArray%.prototype.keys ( ), https://tc39.es/ecma262/#sec-%typedarray%.prototype.keys
@@ -1643,7 +1643,7 @@ JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::to_locale_string)
         if (!next_element.is_nullish()) {
             // i. Let S be ? ToString(? Invoke(nextElement, "toLocaleString", « locales, options »)).
             auto locale_string_value = TRY(next_element.invoke(vm, vm.names.toLocaleString, locales, options));
-            auto locale_string = TRY(locale_string_value.to_deprecated_string(vm));
+            auto locale_string = TRY(locale_string_value.to_byte_string(vm));
 
             // ii. Set R to the string-concatenation of R and S.
             builder.append(locale_string);
@@ -1653,7 +1653,7 @@ JS_DEFINE_NATIVE_FUNCTION(TypedArrayPrototype::to_locale_string)
     }
 
     // 7. Return R.
-    return PrimitiveString::create(vm, builder.to_deprecated_string());
+    return PrimitiveString::create(vm, builder.to_byte_string());
 }
 
 // 23.2.3.32 %TypedArray%.prototype.toReversed ( ), https://tc39.es/ecma262/#sec-%typedarray%.prototype.toreversed
diff --git a/Userland/Libraries/LibJS/Runtime/Utf16String.cpp b/Userland/Libraries/LibJS/Runtime/Utf16String.cpp
index d0f1fb118e9..295165e8f8c 100644
--- a/Userland/Libraries/LibJS/Runtime/Utf16String.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Utf16String.cpp
@@ -107,9 +107,9 @@ String Utf16String::to_utf8() const
     return MUST(view().to_utf8(Utf16View::AllowInvalidCodeUnits::Yes));
 }
 
-DeprecatedString Utf16String::to_deprecated_string() const
+ByteString Utf16String::to_byte_string() const
 {
-    return MUST(view().to_deprecated_string(Utf16View::AllowInvalidCodeUnits::Yes));
+    return MUST(view().to_byte_string(Utf16View::AllowInvalidCodeUnits::Yes));
 }
 
 u16 Utf16String::code_unit_at(size_t index) const
diff --git a/Userland/Libraries/LibJS/Runtime/Utf16String.h b/Userland/Libraries/LibJS/Runtime/Utf16String.h
index 2319dcd4135..4e08afa4aa8 100644
--- a/Userland/Libraries/LibJS/Runtime/Utf16String.h
+++ b/Userland/Libraries/LibJS/Runtime/Utf16String.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefCounted.h>
 #include <AK/Types.h>
@@ -51,7 +51,7 @@ public:
     Utf16View substring_view(size_t code_unit_offset) const;
 
     [[nodiscard]] String to_utf8() const;
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
+    [[nodiscard]] ByteString to_byte_string() const;
     u16 code_unit_at(size_t index) const;
 
     size_t length_in_code_units() const;
diff --git a/Userland/Libraries/LibJS/Runtime/VM.cpp b/Userland/Libraries/LibJS/Runtime/VM.cpp
index ee473b9cb44..3a35127b5b5 100644
--- a/Userland/Libraries/LibJS/Runtime/VM.cpp
+++ b/Userland/Libraries/LibJS/Runtime/VM.cpp
@@ -106,7 +106,7 @@ VM::VM(OwnPtr<CustomData> custom_data, ErrorMessages error_messages)
     };
 
     host_get_supported_import_attributes = [&] {
-        return Vector<DeprecatedString> { "type" };
+        return Vector<ByteString> { "type" };
     };
 
     // 19.2.1.2 HostEnsureCanCompileStrings ( callerRealm, calleeRealm ), https://tc39.es/ecma262/#sec-hostensurecancompilestrings
@@ -746,7 +746,7 @@ ScriptOrModule VM::get_active_script_or_module() const
     return m_execution_context_stack[0]->script_or_module;
 }
 
-VM::StoredModule* VM::get_stored_module(ImportedModuleReferrer const&, DeprecatedString const& filename, DeprecatedString const&)
+VM::StoredModule* VM::get_stored_module(ImportedModuleReferrer const&, ByteString const& filename, ByteString const&)
 {
     // Note the spec says:
     // If this operation is called multiple times with the same (referrer, specifier) pair and it performs
@@ -803,7 +803,7 @@ ThrowCompletionOr<void> VM::link_and_eval_module(CyclicModule& module)
     return {};
 }
 
-static DeprecatedString resolve_module_filename(StringView filename, StringView module_type)
+static ByteString resolve_module_filename(StringView filename, StringView module_type)
 {
     auto extensions = Vector<StringView, 2> { "js"sv, "mjs"sv };
     if (module_type == "json"sv)
@@ -811,14 +811,14 @@ static DeprecatedString resolve_module_filename(StringView filename, StringView
     if (!FileSystem::exists(filename)) {
         for (auto extension : extensions) {
             // import "./foo" -> import "./foo.ext"
-            auto resolved_filepath = DeprecatedString::formatted("{}.{}", filename, extension);
+            auto resolved_filepath = ByteString::formatted("{}.{}", filename, extension);
             if (FileSystem::exists(resolved_filepath))
                 return resolved_filepath;
         }
     } else if (FileSystem::is_directory(filename)) {
         for (auto extension : extensions) {
             // import "./foo" -> import "./foo/index.ext"
-            auto resolved_filepath = LexicalPath::join(filename, DeprecatedString::formatted("index.{}", extension)).string();
+            auto resolved_filepath = LexicalPath::join(filename, ByteString::formatted("index.{}", extension)).string();
             if (FileSystem::exists(resolved_filepath))
                 return resolved_filepath;
         }
@@ -853,7 +853,7 @@ void VM::load_imported_module(ImportedModuleReferrer referrer, ModuleRequest con
         return;
     }
 
-    DeprecatedString module_type;
+    ByteString module_type;
     for (auto& attribute : module_request.attributes) {
         if (attribute.key == "type"sv) {
             module_type = attribute.value;
@@ -890,15 +890,15 @@ void VM::load_imported_module(ImportedModuleReferrer referrer, ModuleRequest con
     dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] resolved filename: '{}'", filename);
 
 #if JS_MODULE_DEBUG
-    DeprecatedString referencing_module_string = referrer.visit(
-        [&](Empty) -> DeprecatedString {
+    ByteString referencing_module_string = referrer.visit(
+        [&](Empty) -> ByteString {
             return ".";
         },
         [&](auto& script_or_module) {
             if constexpr (IsSame<Script*, decltype(script_or_module)>) {
-                return DeprecatedString::formatted("Script @ {}", script_or_module.ptr());
+                return ByteString::formatted("Script @ {}", script_or_module.ptr());
             }
-            return DeprecatedString::formatted("Module @ {}", script_or_module.ptr());
+            return ByteString::formatted("Module @ {}", script_or_module.ptr());
         });
 
     dbgln_if(JS_MODULE_DEBUG, "[JS MODULE] load_imported_module({}, {})", referencing_module_string, filename);
@@ -949,14 +949,14 @@ void VM::load_imported_module(ImportedModuleReferrer referrer, ModuleRequest con
 
         if (module_or_errors.is_error()) {
             VERIFY(module_or_errors.error().size() > 0);
-            return throw_completion<SyntaxError>(module_or_errors.error().first().to_deprecated_string());
+            return throw_completion<SyntaxError>(module_or_errors.error().first().to_byte_string());
         }
 
         auto module = module_or_errors.release_value();
         m_loaded_modules.empend(
             referrer,
             module->filename(),
-            DeprecatedString {}, // Null type
+            ByteString {}, // Null type
             make_handle<Module>(*module),
             true);
 
diff --git a/Userland/Libraries/LibJS/Runtime/VM.h b/Userland/Libraries/LibJS/Runtime/VM.h
index c7514d301fa..78ec07adf4c 100644
--- a/Userland/Libraries/LibJS/Runtime/VM.h
+++ b/Userland/Libraries/LibJS/Runtime/VM.h
@@ -65,9 +65,9 @@ public:
         return m_string_cache;
     }
 
-    HashMap<DeprecatedString, GCPtr<PrimitiveString>>& deprecated_string_cache()
+    HashMap<ByteString, GCPtr<PrimitiveString>>& byte_string_cache()
     {
-        return m_deprecated_string_cache;
+        return m_byte_string_cache;
     }
 
     PrimitiveString& empty_string() { return *m_empty_string; }
@@ -186,7 +186,7 @@ public:
     template<typename T, typename... Args>
     Completion throw_completion(ErrorType type, Args&&... args)
     {
-        return throw_completion<T>(DeprecatedString::formatted(type.message(), forward<Args>(args)...));
+        return throw_completion<T>(ByteString::formatted(type.message(), forward<Args>(args)...));
     }
 
     Value get_new_target();
@@ -234,7 +234,7 @@ public:
     Function<HashMap<PropertyKey, Value>(SourceTextModule&)> host_get_import_meta_properties;
     Function<void(Object*, SourceTextModule const&)> host_finalize_import_meta;
 
-    Function<Vector<DeprecatedString>()> host_get_supported_import_attributes;
+    Function<Vector<ByteString>()> host_get_supported_import_attributes;
 
     void set_dynamic_imports_allowed(bool value) { m_dynamic_imports_allowed = value; }
 
@@ -275,7 +275,7 @@ private:
     Vector<FlatPtr> get_native_stack_trace() const;
 
     HashMap<String, GCPtr<PrimitiveString>> m_string_cache;
-    HashMap<DeprecatedString, GCPtr<PrimitiveString>> m_deprecated_string_cache;
+    HashMap<ByteString, GCPtr<PrimitiveString>> m_byte_string_cache;
 
     Heap m_heap;
 
@@ -298,13 +298,13 @@ private:
 
     struct StoredModule {
         ImportedModuleReferrer referrer;
-        DeprecatedString filename;
-        DeprecatedString type;
+        ByteString filename;
+        ByteString type;
         Handle<Module> module;
         bool has_once_started_linking { false };
     };
 
-    StoredModule* get_stored_module(ImportedModuleReferrer const& script_or_module, DeprecatedString const& filename, DeprecatedString const& type);
+    StoredModule* get_stored_module(ImportedModuleReferrer const& script_or_module, ByteString const& filename, ByteString const& type);
 
     Vector<StoredModule> m_loaded_modules;
 
diff --git a/Userland/Libraries/LibJS/Runtime/Value.cpp b/Userland/Libraries/LibJS/Runtime/Value.cpp
index 9198086a583..c89297c74fc 100644
--- a/Userland/Libraries/LibJS/Runtime/Value.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Value.cpp
@@ -8,8 +8,8 @@
 
 #include <AK/AllOf.h>
 #include <AK/Assertions.h>
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/FloatingPointStringConversions.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringFloatingPointConversions.h>
@@ -212,11 +212,11 @@ String number_to_string(double d, NumberToStringMode mode)
     return builder.to_string().release_value();
 }
 
-DeprecatedString number_to_deprecated_string(double d, NumberToStringMode mode)
+ByteString number_to_byte_string(double d, NumberToStringMode mode)
 {
     StringBuilder builder;
     number_to_string_impl(builder, d, mode);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // 7.2.2 IsArray ( argument ), https://tc39.es/ecma262/#sec-isarray
@@ -439,9 +439,9 @@ ThrowCompletionOr<String> Value::to_string(VM& vm) const
 }
 
 // 7.1.17 ToString ( argument ), https://tc39.es/ecma262/#sec-tostring
-ThrowCompletionOr<DeprecatedString> Value::to_deprecated_string(VM& vm) const
+ThrowCompletionOr<ByteString> Value::to_byte_string(VM& vm) const
 {
-    return TRY(to_string(vm)).to_deprecated_string();
+    return TRY(to_string(vm)).to_byte_string();
 }
 
 ThrowCompletionOr<Utf16String> Value::to_utf16_string(VM& vm) const
@@ -500,7 +500,7 @@ ThrowCompletionOr<Value> Value::to_primitive_slow_case(VM& vm, PreferredType pre
 
         // b. If exoticToPrim is not undefined, then
         if (exotic_to_primitive) {
-            auto hint = [&]() -> DeprecatedString {
+            auto hint = [&]() -> ByteString {
                 switch (preferred_type) {
                 // i. If preferredType is not present, let hint be "default".
                 case PreferredType::Default:
@@ -655,7 +655,7 @@ static Optional<NumberParseResult> parse_number_text(StringView text)
 double string_to_number(StringView string)
 {
     // 1. Let text be StringToCodePoints(str).
-    DeprecatedString text = Utf8View(string).trim(whitespace_characters, AK::TrimMode::Both).as_string();
+    ByteString text = Utf8View(string).trim(whitespace_characters, AK::TrimMode::Both).as_string();
 
     // 2. Let literal be ParseText(text, StringNumericLiteral).
     if (text.is_empty())
@@ -710,7 +710,7 @@ ThrowCompletionOr<Value> Value::to_number_slow_case(VM& vm) const
         return Value(as_bool() ? 1 : 0);
     // 6. If argument is a String, return StringToNumber(argument).
     case STRING_TAG:
-        return string_to_number(as_string().deprecated_string());
+        return string_to_number(as_string().byte_string());
     // 7. Assert: argument is an Object.
     case OBJECT_TAG: {
         // 8. Let primValue be ? ToPrimitive(argument, number).
@@ -764,7 +764,7 @@ ThrowCompletionOr<NonnullGCPtr<BigInt>> Value::to_bigint(VM& vm) const
         return primitive.as_bigint();
     case STRING_TAG: {
         // 1. Let n be ! StringToBigInt(prim).
-        auto bigint = string_to_bigint(vm, primitive.as_string().deprecated_string());
+        auto bigint = string_to_bigint(vm, primitive.as_string().byte_string());
 
         // 2. If n is undefined, throw a SyntaxError exception.
         if (!bigint.has_value())
@@ -894,7 +894,7 @@ ThrowCompletionOr<PropertyKey> Value::to_property_key(VM& vm) const
     }
 
     // 3. Return ! ToString(key).
-    return MUST(key.to_deprecated_string(vm));
+    return MUST(key.to_byte_string(vm));
 }
 
 // 7.1.6 ToInt32 ( argument ), https://tc39.es/ecma262/#sec-toint32
@@ -2212,7 +2212,7 @@ bool same_value_non_number(Value lhs, Value rhs)
     // 5. If x is a String, then
     if (lhs.is_string()) {
         // a. If x and y are exactly the same sequence of code units (same length and same code units at corresponding indices), return true; otherwise, return false.
-        return lhs.as_string().deprecated_string() == rhs.as_string().deprecated_string();
+        return lhs.as_string().byte_string() == rhs.as_string().byte_string();
     }
 
     // 3. If x is undefined, return true.
@@ -2293,7 +2293,7 @@ ThrowCompletionOr<bool> is_loosely_equal(VM& vm, Value lhs, Value rhs)
     // 7. If Type(x) is BigInt and Type(y) is String, then
     if (lhs.is_bigint() && rhs.is_string()) {
         // a. Let n be StringToBigInt(y).
-        auto bigint = string_to_bigint(vm, rhs.as_string().deprecated_string());
+        auto bigint = string_to_bigint(vm, rhs.as_string().byte_string());
 
         // b. If n is undefined, return false.
         if (!bigint.has_value())
@@ -2374,8 +2374,8 @@ ThrowCompletionOr<TriState> is_less_than(VM& vm, Value lhs, Value rhs, bool left
 
     // 3. If px is a String and py is a String, then
     if (x_primitive.is_string() && y_primitive.is_string()) {
-        auto x_string = x_primitive.as_string().deprecated_string();
-        auto y_string = y_primitive.as_string().deprecated_string();
+        auto x_string = x_primitive.as_string().byte_string();
+        auto y_string = y_primitive.as_string().byte_string();
 
         Utf8View x_code_points { x_string };
         Utf8View y_code_points { y_string };
@@ -2410,7 +2410,7 @@ ThrowCompletionOr<TriState> is_less_than(VM& vm, Value lhs, Value rhs, bool left
     // a. If px is a BigInt and py is a String, then
     if (x_primitive.is_bigint() && y_primitive.is_string()) {
         // i. Let ny be StringToBigInt(py).
-        auto y_bigint = string_to_bigint(vm, y_primitive.as_string().deprecated_string());
+        auto y_bigint = string_to_bigint(vm, y_primitive.as_string().byte_string());
 
         // ii. If ny is undefined, return undefined.
         if (!y_bigint.has_value())
@@ -2425,7 +2425,7 @@ ThrowCompletionOr<TriState> is_less_than(VM& vm, Value lhs, Value rhs, bool left
     // b. If px is a String and py is a BigInt, then
     if (x_primitive.is_string() && y_primitive.is_bigint()) {
         // i. Let nx be StringToBigInt(px).
-        auto x_bigint = string_to_bigint(vm, x_primitive.as_string().deprecated_string());
+        auto x_bigint = string_to_bigint(vm, x_primitive.as_string().byte_string());
 
         // ii. If nx is undefined, return undefined.
         if (!x_bigint.has_value())
diff --git a/Userland/Libraries/LibJS/Runtime/Value.h b/Userland/Libraries/LibJS/Runtime/Value.h
index 2a968628813..da72d718b39 100644
--- a/Userland/Libraries/LibJS/Runtime/Value.h
+++ b/Userland/Libraries/LibJS/Runtime/Value.h
@@ -10,7 +10,7 @@
 
 #include <AK/Assertions.h>
 #include <AK/BitCast.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/Forward.h>
 #include <AK/Function.h>
@@ -374,7 +374,7 @@ public:
     u64 encoded() const { return m_value.encoded; }
 
     ThrowCompletionOr<String> to_string(VM&) const;
-    ThrowCompletionOr<DeprecatedString> to_deprecated_string(VM&) const;
+    ThrowCompletionOr<ByteString> to_byte_string(VM&) const;
     ThrowCompletionOr<Utf16String> to_utf16_string(VM&) const;
     ThrowCompletionOr<NonnullGCPtr<PrimitiveString>> to_primitive_string(VM&);
     ThrowCompletionOr<Value> to_primitive(VM&, PreferredType preferred_type = PreferredType::Default) const;
@@ -575,7 +575,7 @@ enum class NumberToStringMode {
     WithoutExponent,
 };
 [[nodiscard]] String number_to_string(double, NumberToStringMode = NumberToStringMode::WithExponent);
-[[nodiscard]] DeprecatedString number_to_deprecated_string(double, NumberToStringMode = NumberToStringMode::WithExponent);
+[[nodiscard]] ByteString number_to_byte_string(double, NumberToStringMode = NumberToStringMode::WithExponent);
 double string_to_number(StringView);
 
 inline bool Value::operator==(Value const& value) const { return same_value(*this, value); }
diff --git a/Userland/Libraries/LibJS/Runtime/ValueTraits.h b/Userland/Libraries/LibJS/Runtime/ValueTraits.h
index a3c63ddb87a..a8109773aa8 100644
--- a/Userland/Libraries/LibJS/Runtime/ValueTraits.h
+++ b/Userland/Libraries/LibJS/Runtime/ValueTraits.h
@@ -19,7 +19,7 @@ struct ValueTraits : public Traits<Value> {
         VERIFY(!value.is_empty());
         if (value.is_string()) {
             // FIXME: Propagate this error.
-            return value.as_string().deprecated_string().hash();
+            return value.as_string().byte_string().hash();
         }
 
         if (value.is_bigint())
diff --git a/Userland/Libraries/LibJS/Runtime/WeakMapConstructor.cpp b/Userland/Libraries/LibJS/Runtime/WeakMapConstructor.cpp
index eff6e31194b..60815613655 100644
--- a/Userland/Libraries/LibJS/Runtime/WeakMapConstructor.cpp
+++ b/Userland/Libraries/LibJS/Runtime/WeakMapConstructor.cpp
@@ -64,7 +64,7 @@ ThrowCompletionOr<NonnullGCPtr<Object>> WeakMapConstructor::construct(FunctionOb
     // 7. Return ? AddEntriesFromIterable(map, iterable, adder).
     (void)TRY(get_iterator_values(vm, iterable, [&](Value iterator_value) -> Optional<Completion> {
         if (!iterator_value.is_object())
-            return vm.throw_completion<TypeError>(ErrorType::NotAnObject, DeprecatedString::formatted("Iterator value {}", iterator_value.to_string_without_side_effects()));
+            return vm.throw_completion<TypeError>(ErrorType::NotAnObject, ByteString::formatted("Iterator value {}", iterator_value.to_string_without_side_effects()));
 
         auto key = TRY(iterator_value.as_object().get(0));
         auto value = TRY(iterator_value.as_object().get(1));
diff --git a/Userland/Libraries/LibJS/Script.h b/Userland/Libraries/LibJS/Script.h
index ad0cd703a02..115ee878a93 100644
--- a/Userland/Libraries/LibJS/Script.h
+++ b/Userland/Libraries/LibJS/Script.h
@@ -47,7 +47,7 @@ private:
     Vector<ModuleWithSpecifier> m_loaded_modules; // [[LoadedModules]]
 
     // Needed for potential lookups of modules.
-    DeprecatedString m_filename;
+    ByteString m_filename;
     HostDefined* m_host_defined { nullptr }; // [[HostDefined]]
 };
 
diff --git a/Userland/Libraries/LibJS/SourceRange.h b/Userland/Libraries/LibJS/SourceRange.h
index eec5e3c7df9..abd8f67b6e6 100644
--- a/Userland/Libraries/LibJS/SourceRange.h
+++ b/Userland/Libraries/LibJS/SourceRange.h
@@ -22,7 +22,7 @@ struct SourceRange {
     Position start;
     Position end;
 
-    DeprecatedString filename() const;
+    ByteString filename() const;
 };
 
 struct UnrealizedSourceRange {
diff --git a/Userland/Libraries/LibJS/Token.cpp b/Userland/Libraries/LibJS/Token.cpp
index 42f0234fc8b..7e9b2a4ca37 100644
--- a/Userland/Libraries/LibJS/Token.cpp
+++ b/Userland/Libraries/LibJS/Token.cpp
@@ -93,14 +93,14 @@ static u32 hex2int(char x)
     return 10u + (to_ascii_lowercase(x) - 'a');
 }
 
-DeprecatedString Token::string_value(StringValueStatus& status) const
+ByteString Token::string_value(StringValueStatus& status) const
 {
     VERIFY(type() == TokenType::StringLiteral || type() == TokenType::TemplateLiteralString);
 
     auto is_template = type() == TokenType::TemplateLiteralString;
     GenericLexer lexer(is_template ? value() : value().substring_view(1, value().length() - 2));
 
-    auto encoding_failure = [&status](StringValueStatus parse_status) -> DeprecatedString {
+    auto encoding_failure = [&status](StringValueStatus parse_status) -> ByteString {
         status = parse_status;
         return {};
     };
@@ -174,7 +174,7 @@ DeprecatedString Token::string_value(StringValueStatus& status) const
 
         // In non-strict mode LegacyOctalEscapeSequence is allowed in strings:
         // https://tc39.es/ecma262/#sec-additional-syntax-string-literals
-        Optional<DeprecatedString> octal_str;
+        Optional<ByteString> octal_str;
 
         auto is_octal_digit = [](char ch) { return ch >= '0' && ch <= '7'; };
         auto is_zero_to_three = [](char ch) { return ch >= '0' && ch <= '3'; };
@@ -210,11 +210,11 @@ DeprecatedString Token::string_value(StringValueStatus& status) const
         lexer.retreat();
         builder.append(lexer.consume_escaped_character('\\', "b\bf\fn\nr\rt\tv\v"sv));
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // 12.8.6.2 Static Semantics: TRV, https://tc39.es/ecma262/#sec-static-semantics-trv
-DeprecatedString Token::raw_template_value() const
+ByteString Token::raw_template_value() const
 {
     return value().replace("\r\n"sv, "\n"sv, ReplaceMode::All).replace("\r"sv, "\n"sv, ReplaceMode::All);
 }
diff --git a/Userland/Libraries/LibJS/Token.h b/Userland/Libraries/LibJS/Token.h
index 9f2d2d3821a..4058e4202b4 100644
--- a/Userland/Libraries/LibJS/Token.h
+++ b/Userland/Libraries/LibJS/Token.h
@@ -233,8 +233,8 @@ public:
         UnicodeEscapeOverflow,
         LegacyOctalEscapeSequence,
     };
-    DeprecatedString string_value(StringValueStatus& status) const;
-    DeprecatedString raw_template_value() const;
+    ByteString string_value(StringValueStatus& status) const;
+    ByteString raw_template_value() const;
 
     void set_identifier_value(DeprecatedFlyString value)
     {
diff --git a/Userland/Libraries/LibKeyboard/CharacterMap.cpp b/Userland/Libraries/LibKeyboard/CharacterMap.cpp
index 220304bebad..9b6cf632154 100644
--- a/Userland/Libraries/LibKeyboard/CharacterMap.cpp
+++ b/Userland/Libraries/LibKeyboard/CharacterMap.cpp
@@ -12,14 +12,14 @@
 
 namespace Keyboard {
 
-ErrorOr<CharacterMap> CharacterMap::load_from_file(DeprecatedString const& map_name)
+ErrorOr<CharacterMap> CharacterMap::load_from_file(ByteString const& map_name)
 {
     auto result = TRY(CharacterMapFile::load_from_file(map_name));
 
     return CharacterMap(map_name, result);
 }
 
-CharacterMap::CharacterMap(DeprecatedString const& map_name, CharacterMapData const& map_data)
+CharacterMap::CharacterMap(ByteString const& map_name, CharacterMapData const& map_data)
     : m_character_map_data(map_data)
     , m_character_map_name(map_name)
 {
@@ -41,7 +41,7 @@ ErrorOr<CharacterMap> CharacterMap::fetch_system_map()
     return CharacterMap { keymap_name, map_data };
 }
 
-DeprecatedString const& CharacterMap::character_map_name() const
+ByteString const& CharacterMap::character_map_name() const
 {
     return m_character_map_name;
 }
diff --git a/Userland/Libraries/LibKeyboard/CharacterMap.h b/Userland/Libraries/LibKeyboard/CharacterMap.h
index fa4591014e4..40c1d979617 100644
--- a/Userland/Libraries/LibKeyboard/CharacterMap.h
+++ b/Userland/Libraries/LibKeyboard/CharacterMap.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <LibKeyboard/CharacterMapData.h>
 
@@ -15,18 +15,18 @@ namespace Keyboard {
 class CharacterMap {
 
 public:
-    CharacterMap(DeprecatedString const& map_name, CharacterMapData const& map_data);
-    static ErrorOr<CharacterMap> load_from_file(DeprecatedString const& filename);
+    CharacterMap(ByteString const& map_name, CharacterMapData const& map_data);
+    static ErrorOr<CharacterMap> load_from_file(ByteString const& filename);
 
     int set_system_map();
     static ErrorOr<CharacterMap> fetch_system_map();
 
     CharacterMapData const& character_map_data() const { return m_character_map_data; }
-    DeprecatedString const& character_map_name() const;
+    ByteString const& character_map_name() const;
 
 private:
     CharacterMapData m_character_map_data;
-    DeprecatedString m_character_map_name;
+    ByteString m_character_map_name;
 };
 
 }
diff --git a/Userland/Libraries/LibKeyboard/CharacterMapFile.cpp b/Userland/Libraries/LibKeyboard/CharacterMapFile.cpp
index 56efd8c2072..c87f5b0e47d 100644
--- a/Userland/Libraries/LibKeyboard/CharacterMapFile.cpp
+++ b/Userland/Libraries/LibKeyboard/CharacterMapFile.cpp
@@ -11,7 +11,7 @@
 
 namespace Keyboard {
 
-ErrorOr<CharacterMapData> CharacterMapFile::load_from_file(DeprecatedString const& filename)
+ErrorOr<CharacterMapData> CharacterMapFile::load_from_file(ByteString const& filename)
 {
     auto path = filename;
     if (!path.ends_with(".json"sv)) {
@@ -19,7 +19,7 @@ ErrorOr<CharacterMapData> CharacterMapFile::load_from_file(DeprecatedString cons
         full_path.append("/res/keymaps/"sv);
         full_path.append(filename);
         full_path.append(".json"sv);
-        path = full_path.to_deprecated_string();
+        path = full_path.to_byte_string();
     }
 
     auto file = TRY(Core::File::open(path, Core::File::OpenMode::Read));
@@ -55,7 +55,7 @@ ErrorOr<CharacterMapData> CharacterMapFile::load_from_file(DeprecatedString cons
     return character_map;
 }
 
-Vector<u32> CharacterMapFile::read_map(JsonObject const& json, DeprecatedString const& name)
+Vector<u32> CharacterMapFile::read_map(JsonObject const& json, ByteString const& name)
 {
     if (!json.has(name))
         return {};
diff --git a/Userland/Libraries/LibKeyboard/CharacterMapFile.h b/Userland/Libraries/LibKeyboard/CharacterMapFile.h
index 0843ca54afc..2bdb9dd867c 100644
--- a/Userland/Libraries/LibKeyboard/CharacterMapFile.h
+++ b/Userland/Libraries/LibKeyboard/CharacterMapFile.h
@@ -14,10 +14,10 @@ namespace Keyboard {
 class CharacterMapFile {
 
 public:
-    static ErrorOr<CharacterMapData> load_from_file(DeprecatedString const& filename);
+    static ErrorOr<CharacterMapData> load_from_file(ByteString const& filename);
 
 private:
-    static Vector<u32> read_map(JsonObject const& json, DeprecatedString const& name);
+    static Vector<u32> read_map(JsonObject const& json, ByteString const& name);
 };
 
 }
diff --git a/Userland/Libraries/LibLine/Editor.cpp b/Userland/Libraries/LibLine/Editor.cpp
index c64ac498f3a..a431c95a8c1 100644
--- a/Userland/Libraries/LibLine/Editor.cpp
+++ b/Userland/Libraries/LibLine/Editor.cpp
@@ -230,11 +230,11 @@ void Editor::get_terminal_size()
     m_num_lines = ws.ws_row;
 }
 
-void Editor::add_to_history(DeprecatedString const& line)
+void Editor::add_to_history(ByteString const& line)
 {
     if (line.is_empty())
         return;
-    DeprecatedString histcontrol = getenv("HISTCONTROL");
+    ByteString histcontrol = getenv("HISTCONTROL");
     auto ignoredups = histcontrol == "ignoredups" || histcontrol == "ignoreboth";
     auto ignorespace = histcontrol == "ignorespace" || histcontrol == "ignoreboth";
     if (ignoredups && !m_history.is_empty() && line == m_history.last().entry)
@@ -270,7 +270,7 @@ ErrorOr<Vector<Editor::HistoryEntry>> Editor::try_load_history(StringView path)
     return history;
 }
 
-bool Editor::load_history(DeprecatedString const& path)
+bool Editor::load_history(ByteString const& path)
 {
     auto history_or_error = try_load_history(path);
     if (history_or_error.is_error())
@@ -322,7 +322,7 @@ static void merge(It0&& begin0, It0 const& end0, It1&& begin1, It1 const& end1,
     }
 }
 
-bool Editor::save_history(DeprecatedString const& path)
+bool Editor::save_history(ByteString const& path)
 {
     // Note: Use a dummy entry to simplify merging.
     Vector<HistoryEntry> final_history { { "", 0 } };
@@ -345,7 +345,7 @@ bool Editor::save_history(DeprecatedString const& path)
     // Skip the dummy entry:
     for (auto iter = final_history.begin() + 1; iter != final_history.end(); ++iter) {
         auto const& entry = *iter;
-        auto buffer = DeprecatedString::formatted("{}::{}\n\n", entry.timestamp, entry.entry);
+        auto buffer = ByteString::formatted("{}::{}\n\n", entry.timestamp, entry.entry);
         auto maybe_error = file->write_until_depleted(buffer.bytes());
         if (maybe_error.is_error())
             return false;
@@ -373,7 +373,7 @@ void Editor::insert(Utf32View const& string)
         insert(string.code_points()[i]);
 }
 
-void Editor::insert(DeprecatedString const& string)
+void Editor::insert(ByteString const& string)
 {
     for (auto ch : Utf8View { string })
         insert(ch);
@@ -389,7 +389,7 @@ void Editor::insert(u32 const cp)
 {
     StringBuilder builder;
     builder.append(Utf32View(&cp, 1));
-    auto str = builder.to_deprecated_string();
+    auto str = builder.to_byte_string();
     if (m_pending_chars.try_append(str.characters(), str.length()).is_error())
         return;
 
@@ -419,7 +419,7 @@ void Editor::register_key_input_callback(KeyBinding const& binding)
         return register_key_input_callback(binding.keys, move(internal_function));
     }
 
-    return register_key_input_callback(binding.keys, [binding = DeprecatedString(binding.binding)](auto& editor) {
+    return register_key_input_callback(binding.keys, [binding = ByteString(binding.binding)](auto& editor) {
         editor.insert(binding);
         return false;
     });
@@ -703,7 +703,7 @@ ErrorOr<void> Editor::really_quit_event_loop()
     return {};
 }
 
-auto Editor::get_line(DeprecatedString const& prompt) -> Result<DeprecatedString, Editor::Error>
+auto Editor::get_line(ByteString const& prompt) -> Result<ByteString, Editor::Error>
 {
     initialize();
     m_is_editing = true;
@@ -727,7 +727,7 @@ auto Editor::get_line(DeprecatedString const& prompt) -> Result<DeprecatedString
         }
         restore();
         if (line) {
-            DeprecatedString result { line, (size_t)line_length, Chomp };
+            ByteString result { line, (size_t)line_length, Chomp };
             free(line);
             return result;
         }
@@ -787,7 +787,7 @@ auto Editor::get_line(DeprecatedString const& prompt) -> Result<DeprecatedString
     if (loop.exec() == Retry)
         return get_line(prompt);
 
-    return m_input_error.has_value() ? Result<DeprecatedString, Editor::Error> { m_input_error.value() } : Result<DeprecatedString, Editor::Error> { m_returned_line };
+    return m_input_error.has_value() ? Result<ByteString, Editor::Error> { m_input_error.value() } : Result<ByteString, Editor::Error> { m_returned_line };
 }
 
 ErrorOr<void> Editor::try_update_once()
@@ -944,7 +944,7 @@ ErrorOr<void> Editor::handle_read_event()
         case InputState::CSIExpectFinal: {
             m_state = m_previous_free_state;
             auto is_in_paste = m_state == InputState::Paste;
-            for (auto& parameter : DeprecatedString::copy(csi_parameter_bytes).split(';')) {
+            for (auto& parameter : ByteString::copy(csi_parameter_bytes).split(';')) {
                 if (auto value = parameter.to_uint(); value.has_value())
                     csi_parameters.append(value.value());
                 else
@@ -1532,14 +1532,14 @@ ErrorOr<void> Editor::refresh_display()
             dbgln("Drawn Spans:");
             for (auto& sentry : m_drawn_spans.m_spans_starting) {
                 for (auto& entry : sentry.value) {
-                    dbgln("{}-{}: {}", sentry.key, entry.key, entry.value.to_deprecated_string());
+                    dbgln("{}-{}: {}", sentry.key, entry.key, entry.value.to_byte_string());
                 }
             }
             dbgln("==========================================================================");
             dbgln("Current Spans:");
             for (auto& sentry : m_current_spans.m_spans_starting) {
                 for (auto& entry : sentry.value) {
-                    dbgln("{}-{}: {}", sentry.key, entry.key, entry.value.to_deprecated_string());
+                    dbgln("{}-{}: {}", sentry.key, entry.key, entry.value.to_byte_string());
                 }
             }
         }
@@ -1613,7 +1613,7 @@ ErrorOr<void> Editor::reposition_cursor(Stream& stream, bool to_end)
 
 ErrorOr<void> VT::move_absolute(u32 row, u32 col, Stream& stream)
 {
-    return stream.write_until_depleted(DeprecatedString::formatted("\033[{};{}H", row, col).bytes());
+    return stream.write_until_depleted(ByteString::formatted("\033[{};{}H", row, col).bytes());
 }
 
 ErrorOr<void> VT::move_relative(int row, int col, Stream& stream)
@@ -1630,9 +1630,9 @@ ErrorOr<void> VT::move_relative(int row, int col, Stream& stream)
         col = -col;
 
     if (row > 0)
-        TRY(stream.write_until_depleted(DeprecatedString::formatted("\033[{}{}", row, x_op).bytes()));
+        TRY(stream.write_until_depleted(ByteString::formatted("\033[{}{}", row, x_op).bytes()));
     if (col > 0)
-        TRY(stream.write_until_depleted(DeprecatedString::formatted("\033[{}{}", col, y_op).bytes()));
+        TRY(stream.write_until_depleted(ByteString::formatted("\033[{}{}", col, y_op).bytes()));
 
     return {};
 }
@@ -1662,36 +1662,36 @@ Style Editor::find_applicable_style(size_t offset) const
     return style;
 }
 
-DeprecatedString Style::Background::to_vt_escape() const
+ByteString Style::Background::to_vt_escape() const
 {
     if (is_default())
         return "";
 
     if (m_is_rgb) {
-        return DeprecatedString::formatted("\e[48;2;{};{};{}m", m_rgb_color[0], m_rgb_color[1], m_rgb_color[2]);
+        return ByteString::formatted("\e[48;2;{};{};{}m", m_rgb_color[0], m_rgb_color[1], m_rgb_color[2]);
     } else {
-        return DeprecatedString::formatted("\e[{}m", (u8)m_xterm_color + 40);
+        return ByteString::formatted("\e[{}m", (u8)m_xterm_color + 40);
     }
 }
 
-DeprecatedString Style::Foreground::to_vt_escape() const
+ByteString Style::Foreground::to_vt_escape() const
 {
     if (is_default())
         return "";
 
     if (m_is_rgb) {
-        return DeprecatedString::formatted("\e[38;2;{};{};{}m", m_rgb_color[0], m_rgb_color[1], m_rgb_color[2]);
+        return ByteString::formatted("\e[38;2;{};{};{}m", m_rgb_color[0], m_rgb_color[1], m_rgb_color[2]);
     } else {
-        return DeprecatedString::formatted("\e[{}m", (u8)m_xterm_color + 30);
+        return ByteString::formatted("\e[{}m", (u8)m_xterm_color + 30);
     }
 }
 
-DeprecatedString Style::Hyperlink::to_vt_escape(bool starting) const
+ByteString Style::Hyperlink::to_vt_escape(bool starting) const
 {
     if (is_empty())
         return "";
 
-    return DeprecatedString::formatted("\e]8;;{}\e\\", starting ? m_link : DeprecatedString::empty());
+    return ByteString::formatted("\e]8;;{}\e\\", starting ? m_link : ByteString::empty());
 }
 
 void Style::unify_with(Style const& other, bool prefer_other)
@@ -1720,7 +1720,7 @@ void Style::unify_with(Style const& other, bool prefer_other)
     m_is_empty &= other.m_is_empty;
 }
 
-DeprecatedString Style::to_deprecated_string() const
+ByteString Style::to_byte_string() const
 {
     StringBuilder builder;
     builder.append("Style { "sv);
@@ -1767,13 +1767,13 @@ DeprecatedString Style::to_deprecated_string() const
 
     builder.append('}');
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 ErrorOr<void> VT::apply_style(Style const& style, Stream& stream, bool is_starting)
 {
     if (is_starting) {
-        TRY(stream.write_until_depleted(DeprecatedString::formatted("\033[{};{};{}m{}{}{}",
+        TRY(stream.write_until_depleted(ByteString::formatted("\033[{};{};{}m{}{}{}",
             style.bold() ? 1 : 22,
             style.underline() ? 4 : 24,
             style.italic() ? 3 : 23,
@@ -1795,7 +1795,7 @@ ErrorOr<void> VT::clear_lines(size_t count_above, size_t count_below, Stream& st
     } else {
         // Go down count_below lines.
         if (count_below > 0)
-            TRY(stream.write_until_depleted(DeprecatedString::formatted("\033[{}B", count_below).bytes()));
+            TRY(stream.write_until_depleted(ByteString::formatted("\033[{}B", count_below).bytes()));
         // Then clear lines going upwards.
         for (size_t i = count_below + count_above; i > 0; --i) {
             TRY(stream.write_until_depleted("\033[2K"sv.bytes()));
@@ -2190,11 +2190,11 @@ Result<Vector<size_t, 2>, Editor::Error> Editor::vt_dsr()
     return Vector<size_t, 2> { row, col };
 }
 
-DeprecatedString Editor::line(size_t up_to_index) const
+ByteString Editor::line(size_t up_to_index) const
 {
     StringBuilder builder;
     builder.append(Utf32View { m_buffer.data(), min(m_buffer.size(), up_to_index) });
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 void Editor::remove_at_index(size_t index)
@@ -2316,11 +2316,11 @@ bool Editor::Spans::contains_up_to_offset(Spans const& other, size_t offset) con
                     if constexpr (LINE_EDITOR_DEBUG) {
                         dbgln("Compare for {}-{} failed, no entry", entry.key, left_entry.key);
                         for (auto& x : entry.value)
-                            dbgln("Have: {}-{} = {}", entry.key, x.key, x.value.to_deprecated_string());
+                            dbgln("Have: {}-{} = {}", entry.key, x.key, x.value.to_byte_string());
                     }
                     return false;
                 } else if (value_it->value != left_entry.value) {
-                    dbgln_if(LINE_EDITOR_DEBUG, "Compare for {}-{} failed, different values: {} != {}", entry.key, left_entry.key, value_it->value.to_deprecated_string(), left_entry.value.to_deprecated_string());
+                    dbgln_if(LINE_EDITOR_DEBUG, "Compare for {}-{} failed, different values: {} != {}", entry.key, left_entry.key, value_it->value.to_byte_string(), left_entry.value.to_byte_string());
                     return false;
                 }
             }
diff --git a/Userland/Libraries/LibLine/Editor.h b/Userland/Libraries/LibLine/Editor.h
index 923d76d1b76..ef5c32f20a1 100644
--- a/Userland/Libraries/LibLine/Editor.h
+++ b/Userland/Libraries/LibLine/Editor.h
@@ -9,7 +9,7 @@
 
 #include <AK/BinarySearch.h>
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
@@ -42,7 +42,7 @@ struct KeyBinding {
         InternalFunction,
         Insertion,
     } kind { Kind::InternalFunction };
-    DeprecatedString binding;
+    ByteString binding;
 };
 
 struct Configuration {
@@ -67,7 +67,7 @@ struct Configuration {
     };
 
     struct DefaultTextEditor {
-        DeprecatedString command;
+        ByteString command;
     };
 
     Configuration()
@@ -97,7 +97,7 @@ struct Configuration {
     SignalHandler m_signal_mode { SignalHandler::WithSignalHandlers };
     OperationMode operation_mode { OperationMode::Unset };
     Vector<KeyBinding> keybindings;
-    DeprecatedString m_default_text_editor {};
+    ByteString m_default_text_editor {};
     bool enable_bracketed_paste { false };
 };
 
@@ -144,15 +144,15 @@ public:
 
     ~Editor();
 
-    Result<DeprecatedString, Error> get_line(DeprecatedString const& prompt);
+    Result<ByteString, Error> get_line(ByteString const& prompt);
 
     void initialize();
 
     void refetch_default_termios();
 
-    void add_to_history(DeprecatedString const& line);
-    bool load_history(DeprecatedString const& path);
-    bool save_history(DeprecatedString const& path);
+    void add_to_history(ByteString const& line);
+    bool load_history(ByteString const& path);
+    bool save_history(ByteString const& path);
     auto const& history() const { return m_history; }
     bool is_history_dirty() const { return m_history_dirty; }
 
@@ -194,11 +194,11 @@ public:
     }
     Vector<u32, 1024> const& buffer() const { return m_buffer; }
     u32 buffer_at(size_t pos) const { return m_buffer.at(pos); }
-    DeprecatedString line() const { return line(m_buffer.size()); }
-    DeprecatedString line(size_t up_to_index) const;
+    ByteString line() const { return line(m_buffer.size()); }
+    ByteString line(size_t up_to_index) const;
 
     // Only makes sense inside a character_input callback or on_* callback.
-    void set_prompt(DeprecatedString const& prompt)
+    void set_prompt(ByteString const& prompt)
     {
         if (m_cached_prompt_valid)
             m_old_prompt_metrics = m_cached_prompt_metrics;
@@ -208,7 +208,7 @@ public:
     }
 
     void clear_line();
-    void insert(DeprecatedString const&);
+    void insert(ByteString const&);
     void insert(StringView);
     void insert(Utf32View const&);
     void insert(const u32);
@@ -315,7 +315,7 @@ private:
         m_prompt_lines_at_suggestion_initiation = 0;
         m_refresh_needed = true;
         m_input_error.clear();
-        m_returned_line = DeprecatedString::empty();
+        m_returned_line = ByteString::empty();
         m_chars_touched_in_the_middle = 0;
         m_drawn_end_of_line_offset = 0;
         m_drawn_spans = {};
@@ -417,7 +417,7 @@ private:
     ByteBuffer m_pending_chars;
     Vector<char, 512> m_incomplete_data;
     Optional<Error> m_input_error;
-    DeprecatedString m_returned_line;
+    ByteString m_returned_line;
 
     size_t m_cursor { 0 };
     size_t m_drawn_cursor { 0 };
@@ -444,7 +444,7 @@ private:
     OwnPtr<SuggestionDisplay> m_suggestion_display;
     Vector<u32, 32> m_remembered_suggestion_static_data;
 
-    DeprecatedString m_new_prompt;
+    ByteString m_new_prompt;
 
     SuggestionManager m_suggestion_manager;
 
@@ -468,7 +468,7 @@ private:
 
     // FIXME: This should be something more take_first()-friendly.
     struct HistoryEntry {
-        DeprecatedString entry;
+        ByteString entry;
         time_t timestamp;
     };
     Vector<HistoryEntry> m_history;
diff --git a/Userland/Libraries/LibLine/InternalFunctions.cpp b/Userland/Libraries/LibLine/InternalFunctions.cpp
index 098ce00b01d..20cfc674e9f 100644
--- a/Userland/Libraries/LibLine/InternalFunctions.cpp
+++ b/Userland/Libraries/LibLine/InternalFunctions.cpp
@@ -37,7 +37,7 @@ void Editor::search_forwards()
     ScopedValueRollback inline_search_cursor_rollback { m_inline_search_cursor };
     StringBuilder builder;
     builder.append(Utf32View { m_buffer.data(), m_inline_search_cursor });
-    auto search_phrase = builder.to_deprecated_string();
+    auto search_phrase = builder.to_byte_string();
     if (m_search_offset_state == SearchOffsetState::Backwards)
         --m_search_offset;
     if (m_search_offset > 0) {
@@ -64,7 +64,7 @@ void Editor::search_backwards()
     ScopedValueRollback inline_search_cursor_rollback { m_inline_search_cursor };
     StringBuilder builder;
     builder.append(Utf32View { m_buffer.data(), m_inline_search_cursor });
-    auto search_phrase = builder.to_deprecated_string();
+    auto search_phrase = builder.to_byte_string();
     if (m_search_offset_state == SearchOffsetState::Forwards)
         ++m_search_offset;
     if (search(search_phrase, true)) {
@@ -257,7 +257,7 @@ void Editor::enter_search()
 
             StringBuilder builder;
             builder.append(Utf32View { search_editor.buffer().data(), search_editor.buffer().size() });
-            if (!search(builder.to_deprecated_string(), false, false)) {
+            if (!search(builder.to_byte_string(), false, false)) {
                 m_chars_touched_in_the_middle = m_buffer.size();
                 m_refresh_needed = true;
                 m_buffer.clear();
diff --git a/Userland/Libraries/LibLine/Style.h b/Userland/Libraries/LibLine/Style.h
index e05bf5fa9e7..458e1ba4740 100644
--- a/Userland/Libraries/LibLine/Style.h
+++ b/Userland/Libraries/LibLine/Style.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Types.h>
 #include <AK/Utf8View.h>
 #include <AK/Vector.h>
@@ -71,7 +71,7 @@ public:
             : Color(r, g, b)
         {
         }
-        DeprecatedString to_vt_escape() const;
+        ByteString to_vt_escape() const;
     };
 
     struct Foreground : public Color {
@@ -84,7 +84,7 @@ public:
         {
         }
 
-        DeprecatedString to_vt_escape() const;
+        ByteString to_vt_escape() const;
     };
 
     struct Hyperlink {
@@ -98,11 +98,11 @@ public:
 
         Hyperlink() = default;
 
-        DeprecatedString to_vt_escape(bool starting) const;
+        ByteString to_vt_escape(bool starting) const;
 
         bool is_empty() const { return !m_has_link; }
 
-        DeprecatedString m_link;
+        ByteString m_link;
         bool m_has_link { false };
     };
 
@@ -123,7 +123,7 @@ public:
         {
         }
 
-        DeprecatedString replacement;
+        ByteString replacement;
         mutable Utf8View replacement_view;
         Mode mode;
     };
@@ -179,7 +179,7 @@ public:
     bool is_anchored() const { return m_is_anchored; }
     bool is_empty() const { return m_is_empty; }
 
-    DeprecatedString to_deprecated_string() const;
+    ByteString to_byte_string() const;
 
 private:
     bool m_underline { false };
diff --git a/Userland/Libraries/LibLine/SuggestionManager.cpp b/Userland/Libraries/LibLine/SuggestionManager.cpp
index d2625d170eb..9e58306a934 100644
--- a/Userland/Libraries/LibLine/SuggestionManager.cpp
+++ b/Userland/Libraries/LibLine/SuggestionManager.cpp
@@ -106,7 +106,7 @@ SuggestionManager::CompletionAttemptResult SuggestionManager::attempt_completion
             result.avoid_committing_to_single_suggestion = true;
             m_last_shown_suggestion_display_length = 0;
             m_last_shown_suggestion_was_complete = false;
-            m_last_shown_suggestion = DeprecatedString::empty();
+            m_last_shown_suggestion = ByteString::empty();
             return result;
         }
 
@@ -158,7 +158,7 @@ SuggestionManager::CompletionAttemptResult SuggestionManager::attempt_completion
             }
             result.new_completion_mode = CompletionMode::ShowSuggestions;
             m_last_shown_suggestion_was_complete = false;
-            m_last_shown_suggestion = DeprecatedString::empty();
+            m_last_shown_suggestion = ByteString::empty();
         } else {
             result.insert.append(suggestion.text_view().substring_view(suggestion.invariant_offset, suggestion.text_view().length() - suggestion.invariant_offset));
             // Add in the trivia of the last selected suggestion.
diff --git a/Userland/Libraries/LibLine/SuggestionManager.h b/Userland/Libraries/LibLine/SuggestionManager.h
index 4d18a3e4767..b18d4c7e79b 100644
--- a/Userland/Libraries/LibLine/SuggestionManager.h
+++ b/Userland/Libraries/LibLine/SuggestionManager.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/String.h>
 #include <AK/Utf32View.h>
@@ -24,7 +24,7 @@ public:
     static constexpr ForSearchTag ForSearch {};
 
     // Intentionally not explicit. (To allow suggesting bare strings)
-    CompletionSuggestion(DeprecatedString const& completion)
+    CompletionSuggestion(ByteString const& completion)
         : CompletionSuggestion(completion, ""sv, {})
     {
     }
@@ -118,7 +118,7 @@ public:
 
     void reset()
     {
-        m_last_shown_suggestion = DeprecatedString::empty();
+        m_last_shown_suggestion = ByteString::empty();
         m_last_shown_suggestion_display_length = 0;
         m_suggestions.clear();
         m_last_displayed_suggestion_index = 0;
@@ -131,7 +131,7 @@ private:
     }
 
     Vector<CompletionSuggestion> m_suggestions;
-    CompletionSuggestion m_last_shown_suggestion { DeprecatedString::empty() };
+    CompletionSuggestion m_last_shown_suggestion { ByteString::empty() };
     size_t m_last_shown_suggestion_display_length { 0 };
     bool m_last_shown_suggestion_was_complete { false };
     mutable size_t m_next_suggestion_index { 0 };
diff --git a/Userland/Libraries/LibLine/XtermSuggestionDisplay.cpp b/Userland/Libraries/LibLine/XtermSuggestionDisplay.cpp
index 6d4ede13e95..f7af1e7394f 100644
--- a/Userland/Libraries/LibLine/XtermSuggestionDisplay.cpp
+++ b/Userland/Libraries/LibLine/XtermSuggestionDisplay.cpp
@@ -118,8 +118,8 @@ ErrorOr<void> XtermSuggestionDisplay::display(SuggestionManager const& manager)
             TRY(stderr_stream->write_until_depleted(suggestion.text_string().bytes()));
             TRY(stderr_stream->write_until_depleted(suggestion.display_trivia_string().bytes()));
         } else {
-            auto field = DeprecatedString::formatted("{: <{}}  {}", suggestion.text_string(), longest_suggestion_byte_length_without_trivia, suggestion.display_trivia_string());
-            TRY(stderr_stream->write_until_depleted(DeprecatedString::formatted("{: <{}}", field, longest_suggestion_byte_length + 2).bytes()));
+            auto field = ByteString::formatted("{: <{}}  {}", suggestion.text_string(), longest_suggestion_byte_length_without_trivia, suggestion.display_trivia_string());
+            TRY(stderr_stream->write_until_depleted(ByteString::formatted("{: <{}}", field, longest_suggestion_byte_length + 2).bytes()));
             num_printed += longest_suggestion_length + 2;
         }
 
@@ -141,7 +141,7 @@ ErrorOr<void> XtermSuggestionDisplay::display(SuggestionManager const& manager)
     if (m_pages.size() > 1) {
         auto left_arrow = page_index > 0 ? '<' : ' ';
         auto right_arrow = page_index < m_pages.size() - 1 ? '>' : ' ';
-        auto string = DeprecatedString::formatted("{:c} page {} of {} {:c}", left_arrow, page_index + 1, m_pages.size(), right_arrow);
+        auto string = ByteString::formatted("{:c} page {} of {} {:c}", left_arrow, page_index + 1, m_pages.size(), right_arrow);
 
         if (string.length() > m_num_columns - 1) {
             // This would overflow into the next line, so just don't print an indicator.
diff --git a/Userland/Libraries/LibManual/SectionNode.cpp b/Userland/Libraries/LibManual/SectionNode.cpp
index d033235ebbd..6949a03225c 100644
--- a/Userland/Libraries/LibManual/SectionNode.cpp
+++ b/Userland/Libraries/LibManual/SectionNode.cpp
@@ -44,9 +44,9 @@ ErrorOr<void> SectionNode::reify_if_needed() const
     m_reified = true;
 
     auto own_path = TRY(path());
-    Core::DirIterator dir_iterator { own_path.to_deprecated_string(), Core::DirIterator::Flags::SkipDots };
-    Vector<DeprecatedString> directories;
-    HashTable<DeprecatedString> files;
+    Core::DirIterator dir_iterator { own_path.to_byte_string(), Core::DirIterator::Flags::SkipDots };
+    Vector<ByteString> directories;
+    HashTable<ByteString> files;
     while (dir_iterator.has_next()) {
         auto entry = dir_iterator.next();
         if (entry->type == Core::DirectoryEntry::Type::Directory)
@@ -64,7 +64,7 @@ ErrorOr<void> SectionNode::reify_if_needed() const
     for (auto const& directory : directories) {
         LexicalPath lexical_path(directory);
         RefPtr<PageNode> associated_page;
-        auto matching_page_name = DeprecatedString::formatted("{}.md", directory);
+        auto matching_page_name = ByteString::formatted("{}.md", directory);
         if (files.remove(matching_page_name))
             associated_page = TRY(try_make_ref_counted<PageNode>(*this, TRY(String::from_utf8(lexical_path.title()))));
 
diff --git a/Userland/Libraries/LibMarkdown/Block.h b/Userland/Libraries/LibMarkdown/Block.h
index ef4cd706d56..c764c3ba18d 100644
--- a/Userland/Libraries/LibMarkdown/Block.h
+++ b/Userland/Libraries/LibMarkdown/Block.h
@@ -18,8 +18,8 @@ class Block {
 public:
     virtual ~Block() = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const = 0;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const = 0;
+    virtual ByteString render_to_html(bool tight = false) const = 0;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const = 0;
     virtual RecursionDecision walk(Visitor&) const = 0;
 };
 
diff --git a/Userland/Libraries/LibMarkdown/BlockQuote.cpp b/Userland/Libraries/LibMarkdown/BlockQuote.cpp
index ac40a2650ba..7066a1d71b1 100644
--- a/Userland/Libraries/LibMarkdown/BlockQuote.cpp
+++ b/Userland/Libraries/LibMarkdown/BlockQuote.cpp
@@ -11,21 +11,21 @@
 
 namespace Markdown {
 
-DeprecatedString BlockQuote::render_to_html(bool) const
+ByteString BlockQuote::render_to_html(bool) const
 {
     StringBuilder builder;
     builder.append("<blockquote>\n"sv);
     builder.append(m_contents->render_to_html());
     builder.append("</blockquote>\n"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-Vector<DeprecatedString> BlockQuote::render_lines_for_terminal(size_t view_width) const
+Vector<ByteString> BlockQuote::render_lines_for_terminal(size_t view_width) const
 {
-    Vector<DeprecatedString> lines;
+    Vector<ByteString> lines;
     size_t child_width = view_width < 4 ? 0 : view_width - 4;
     for (auto& line : m_contents->render_lines_for_terminal(child_width))
-        lines.append(DeprecatedString::formatted("    {}", line));
+        lines.append(ByteString::formatted("    {}", line));
 
     return lines;
 }
diff --git a/Userland/Libraries/LibMarkdown/BlockQuote.h b/Userland/Libraries/LibMarkdown/BlockQuote.h
index e09912e16c0..e20e4678d58 100644
--- a/Userland/Libraries/LibMarkdown/BlockQuote.h
+++ b/Userland/Libraries/LibMarkdown/BlockQuote.h
@@ -21,8 +21,8 @@ public:
     }
     virtual ~BlockQuote() override = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const override;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const override;
+    virtual ByteString render_to_html(bool tight = false) const override;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const override;
     virtual RecursionDecision walk(Visitor&) const override;
 
     static OwnPtr<BlockQuote> parse(LineIterator& lines);
diff --git a/Userland/Libraries/LibMarkdown/CodeBlock.cpp b/Userland/Libraries/LibMarkdown/CodeBlock.cpp
index 71eb00c03b9..6f897390283 100644
--- a/Userland/Libraries/LibMarkdown/CodeBlock.cpp
+++ b/Userland/Libraries/LibMarkdown/CodeBlock.cpp
@@ -14,7 +14,7 @@
 
 namespace Markdown {
 
-DeprecatedString CodeBlock::render_to_html(bool) const
+ByteString CodeBlock::render_to_html(bool) const
 {
     StringBuilder builder;
 
@@ -51,12 +51,12 @@ DeprecatedString CodeBlock::render_to_html(bool) const
 
     builder.append("</pre>\n"sv);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-Vector<DeprecatedString> CodeBlock::render_lines_for_terminal(size_t) const
+Vector<ByteString> CodeBlock::render_lines_for_terminal(size_t) const
 {
-    Vector<DeprecatedString> lines;
+    Vector<ByteString> lines;
 
     // Do not indent too much if we are in the synopsis
     auto indentation = "    "sv;
@@ -67,7 +67,7 @@ Vector<DeprecatedString> CodeBlock::render_lines_for_terminal(size_t) const
     }
 
     for (auto const& line : m_code.split('\n', SplitBehavior::KeepEmpty))
-        lines.append(DeprecatedString::formatted("{}{}", indentation, line));
+        lines.append(ByteString::formatted("{}{}", indentation, line));
 
     return lines;
 }
@@ -173,7 +173,7 @@ OwnPtr<CodeBlock> CodeBlock::parse_backticks(LineIterator& lines, Heading* curre
         builder.append('\n');
     }
 
-    return make<CodeBlock>(language, style, builder.to_deprecated_string(), current_section);
+    return make<CodeBlock>(language, style, builder.to_byte_string(), current_section);
 }
 
 OwnPtr<CodeBlock> CodeBlock::parse_indent(LineIterator& lines)
@@ -196,6 +196,6 @@ OwnPtr<CodeBlock> CodeBlock::parse_indent(LineIterator& lines)
         builder.append('\n');
     }
 
-    return make<CodeBlock>("", "", builder.to_deprecated_string(), nullptr);
+    return make<CodeBlock>("", "", builder.to_byte_string(), nullptr);
 }
 }
diff --git a/Userland/Libraries/LibMarkdown/CodeBlock.h b/Userland/Libraries/LibMarkdown/CodeBlock.h
index 1163cf252e8..0667e80eaec 100644
--- a/Userland/Libraries/LibMarkdown/CodeBlock.h
+++ b/Userland/Libraries/LibMarkdown/CodeBlock.h
@@ -17,7 +17,7 @@ namespace Markdown {
 
 class CodeBlock final : public Block {
 public:
-    CodeBlock(DeprecatedString const& language, DeprecatedString const& style, DeprecatedString const& code, Heading* current_section)
+    CodeBlock(ByteString const& language, ByteString const& style, ByteString const& code, Heading* current_section)
         : m_code(move(code))
         , m_language(language)
         , m_style(style)
@@ -26,15 +26,15 @@ public:
     }
     virtual ~CodeBlock() override = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const override;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const override;
+    virtual ByteString render_to_html(bool tight = false) const override;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const override;
     virtual RecursionDecision walk(Visitor&) const override;
     static OwnPtr<CodeBlock> parse(LineIterator& lines, Heading* current_section);
 
 private:
-    DeprecatedString m_code;
-    DeprecatedString m_language;
-    DeprecatedString m_style;
+    ByteString m_code;
+    ByteString m_language;
+    ByteString m_style;
     Heading* m_current_section;
 
     static OwnPtr<CodeBlock> parse_backticks(LineIterator& lines, Heading* current_section);
diff --git a/Userland/Libraries/LibMarkdown/CommentBlock.cpp b/Userland/Libraries/LibMarkdown/CommentBlock.cpp
index b885b32e941..e7054fbeadc 100644
--- a/Userland/Libraries/LibMarkdown/CommentBlock.cpp
+++ b/Userland/Libraries/LibMarkdown/CommentBlock.cpp
@@ -11,7 +11,7 @@
 
 namespace Markdown {
 
-DeprecatedString CommentBlock::render_to_html(bool) const
+ByteString CommentBlock::render_to_html(bool) const
 {
     StringBuilder builder;
 
@@ -20,12 +20,12 @@ DeprecatedString CommentBlock::render_to_html(bool) const
     // TODO: This is probably incorrect, because we technically need to escape "--" in some form. However, Browser does not care about this.
     builder.append("-->\n"sv);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-Vector<DeprecatedString> CommentBlock::render_lines_for_terminal(size_t) const
+Vector<ByteString> CommentBlock::render_lines_for_terminal(size_t) const
 {
-    return Vector<DeprecatedString> {};
+    return Vector<ByteString> {};
 }
 
 RecursionDecision CommentBlock::walk(Visitor& visitor) const
@@ -69,7 +69,7 @@ OwnPtr<CommentBlock> CommentBlock::parse(LineIterator& lines)
         line = *lines;
     }
 
-    return make<CommentBlock>(builder.to_deprecated_string());
+    return make<CommentBlock>(builder.to_byte_string());
 }
 
 }
diff --git a/Userland/Libraries/LibMarkdown/CommentBlock.h b/Userland/Libraries/LibMarkdown/CommentBlock.h
index 381c5361452..388d7eab63f 100644
--- a/Userland/Libraries/LibMarkdown/CommentBlock.h
+++ b/Userland/Libraries/LibMarkdown/CommentBlock.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/OwnPtr.h>
 #include <LibMarkdown/Block.h>
 #include <LibMarkdown/LineIterator.h>
@@ -16,19 +16,19 @@ namespace Markdown {
 
 class CommentBlock final : public Block {
 public:
-    CommentBlock(DeprecatedString const& comment)
+    CommentBlock(ByteString const& comment)
         : m_comment(comment)
     {
     }
     virtual ~CommentBlock() override = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const override;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const override;
+    virtual ByteString render_to_html(bool tight = false) const override;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const override;
     virtual RecursionDecision walk(Visitor&) const override;
     static OwnPtr<CommentBlock> parse(LineIterator& lines);
 
 private:
-    DeprecatedString m_comment;
+    ByteString m_comment;
 };
 
 }
diff --git a/Userland/Libraries/LibMarkdown/ContainerBlock.cpp b/Userland/Libraries/LibMarkdown/ContainerBlock.cpp
index 7baf3e1afb7..45ae36ef2b4 100644
--- a/Userland/Libraries/LibMarkdown/ContainerBlock.cpp
+++ b/Userland/Libraries/LibMarkdown/ContainerBlock.cpp
@@ -17,7 +17,7 @@
 
 namespace Markdown {
 
-DeprecatedString ContainerBlock::render_to_html(bool tight) const
+ByteString ContainerBlock::render_to_html(bool tight) const
 {
     StringBuilder builder;
 
@@ -37,12 +37,12 @@ DeprecatedString ContainerBlock::render_to_html(bool tight) const
         }
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-Vector<DeprecatedString> ContainerBlock::render_lines_for_terminal(size_t view_width) const
+Vector<ByteString> ContainerBlock::render_lines_for_terminal(size_t view_width) const
 {
-    Vector<DeprecatedString> lines;
+    Vector<ByteString> lines;
 
     for (auto& block : m_blocks) {
         for (auto& line : block->render_lines_for_terminal(view_width))
@@ -97,7 +97,7 @@ OwnPtr<ContainerBlock> ContainerBlock::parse(LineIterator& lines)
     auto flush_paragraph = [&] {
         if (paragraph_text.is_empty())
             return;
-        auto paragraph = make<Paragraph>(Text::parse(paragraph_text.to_deprecated_string()));
+        auto paragraph = make<Paragraph>(Text::parse(paragraph_text.to_byte_string()));
         blocks.append(move(paragraph));
         paragraph_text.clear();
     };
diff --git a/Userland/Libraries/LibMarkdown/ContainerBlock.h b/Userland/Libraries/LibMarkdown/ContainerBlock.h
index dfcd8d94709..aaed1c0a506 100644
--- a/Userland/Libraries/LibMarkdown/ContainerBlock.h
+++ b/Userland/Libraries/LibMarkdown/ContainerBlock.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/OwnPtr.h>
 #include <LibMarkdown/Block.h>
 #include <LibMarkdown/LineIterator.h>
@@ -25,8 +25,8 @@ public:
 
     virtual ~ContainerBlock() override = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const override;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const override;
+    virtual ByteString render_to_html(bool tight = false) const override;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const override;
     virtual RecursionDecision walk(Visitor&) const override;
 
     static OwnPtr<ContainerBlock> parse(LineIterator& lines);
diff --git a/Userland/Libraries/LibMarkdown/Document.cpp b/Userland/Libraries/LibMarkdown/Document.cpp
index 09127445390..3dfb21461ac 100644
--- a/Userland/Libraries/LibMarkdown/Document.cpp
+++ b/Userland/Libraries/LibMarkdown/Document.cpp
@@ -12,7 +12,7 @@
 
 namespace Markdown {
 
-DeprecatedString Document::render_to_html(StringView extra_head_contents) const
+ByteString Document::render_to_html(StringView extra_head_contents) const
 {
     StringBuilder builder;
     builder.append(R"~~~(<!DOCTYPE html>
@@ -35,10 +35,10 @@ DeprecatedString Document::render_to_html(StringView extra_head_contents) const
 </body>
 </html>)~~~"sv);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Document::render_to_inline_html() const
+ByteString Document::render_to_inline_html() const
 {
     return m_container->render_to_html();
 }
diff --git a/Userland/Libraries/LibMarkdown/Document.h b/Userland/Libraries/LibMarkdown/Document.h
index 26016e3bc8a..bdb211dfc5e 100644
--- a/Userland/Libraries/LibMarkdown/Document.h
+++ b/Userland/Libraries/LibMarkdown/Document.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/OwnPtr.h>
 #include <AK/String.h>
 #include <LibMarkdown/Block.h>
@@ -20,8 +20,8 @@ public:
         : m_container(move(container))
     {
     }
-    DeprecatedString render_to_html(StringView extra_head_contents = ""sv) const;
-    DeprecatedString render_to_inline_html() const;
+    ByteString render_to_html(StringView extra_head_contents = ""sv) const;
+    ByteString render_to_inline_html() const;
     ErrorOr<String> render_for_terminal(size_t view_width = 0) const;
 
     /*
diff --git a/Userland/Libraries/LibMarkdown/Heading.cpp b/Userland/Libraries/LibMarkdown/Heading.cpp
index cd3b215be3e..09ea084a909 100644
--- a/Userland/Libraries/LibMarkdown/Heading.cpp
+++ b/Userland/Libraries/LibMarkdown/Heading.cpp
@@ -12,14 +12,14 @@
 
 namespace Markdown {
 
-DeprecatedString Heading::render_to_html(bool) const
+ByteString Heading::render_to_html(bool) const
 {
     auto input = Unicode::normalize(m_text.render_for_raw_print().view(), Unicode::NormalizationForm::NFD);
     auto slugified = MUST(AK::slugify(input));
-    return DeprecatedString::formatted("<h{} id='{}'><a href='#{}'>#</a> {}</h{}>\n", m_level, slugified, slugified, m_text.render_to_html(), m_level);
+    return ByteString::formatted("<h{} id='{}'><a href='#{}'>#</a> {}</h{}>\n", m_level, slugified, slugified, m_text.render_to_html(), m_level);
 }
 
-Vector<DeprecatedString> Heading::render_lines_for_terminal(size_t) const
+Vector<ByteString> Heading::render_lines_for_terminal(size_t) const
 {
     StringBuilder builder;
 
@@ -36,7 +36,7 @@ Vector<DeprecatedString> Heading::render_lines_for_terminal(size_t) const
         break;
     }
 
-    return Vector<DeprecatedString> { builder.to_deprecated_string() };
+    return Vector<ByteString> { builder.to_byte_string() };
 }
 
 RecursionDecision Heading::walk(Visitor& visitor) const
diff --git a/Userland/Libraries/LibMarkdown/Heading.h b/Userland/Libraries/LibMarkdown/Heading.h
index 37da2d0b972..04247a9774b 100644
--- a/Userland/Libraries/LibMarkdown/Heading.h
+++ b/Userland/Libraries/LibMarkdown/Heading.h
@@ -26,8 +26,8 @@ public:
     }
     virtual ~Heading() override = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const override;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const override;
+    virtual ByteString render_to_html(bool tight = false) const override;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const override;
     virtual RecursionDecision walk(Visitor&) const override;
     static OwnPtr<Heading> parse(LineIterator& lines);
 
diff --git a/Userland/Libraries/LibMarkdown/HorizontalRule.cpp b/Userland/Libraries/LibMarkdown/HorizontalRule.cpp
index 4c37a0ad853..416b2e28ff6 100644
--- a/Userland/Libraries/LibMarkdown/HorizontalRule.cpp
+++ b/Userland/Libraries/LibMarkdown/HorizontalRule.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <LibMarkdown/HorizontalRule.h>
 #include <LibMarkdown/Visitor.h>
@@ -12,18 +12,18 @@
 
 namespace Markdown {
 
-DeprecatedString HorizontalRule::render_to_html(bool) const
+ByteString HorizontalRule::render_to_html(bool) const
 {
     return "<hr />\n";
 }
 
-Vector<DeprecatedString> HorizontalRule::render_lines_for_terminal(size_t view_width) const
+Vector<ByteString> HorizontalRule::render_lines_for_terminal(size_t view_width) const
 {
     StringBuilder builder(view_width + 1);
     for (size_t i = 0; i < view_width; ++i)
         builder.append('-');
     builder.append("\n\n"sv);
-    return Vector<DeprecatedString> { builder.to_deprecated_string() };
+    return Vector<ByteString> { builder.to_byte_string() };
 }
 
 RecursionDecision HorizontalRule::walk(Visitor& visitor) const
diff --git a/Userland/Libraries/LibMarkdown/HorizontalRule.h b/Userland/Libraries/LibMarkdown/HorizontalRule.h
index 5512358b1be..bdbc206d57f 100644
--- a/Userland/Libraries/LibMarkdown/HorizontalRule.h
+++ b/Userland/Libraries/LibMarkdown/HorizontalRule.h
@@ -20,8 +20,8 @@ public:
     HorizontalRule() = default;
     virtual ~HorizontalRule() override = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const override;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const override;
+    virtual ByteString render_to_html(bool tight = false) const override;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const override;
     virtual RecursionDecision walk(Visitor&) const override;
     static OwnPtr<HorizontalRule> parse(LineIterator& lines);
 };
diff --git a/Userland/Libraries/LibMarkdown/List.cpp b/Userland/Libraries/LibMarkdown/List.cpp
index 2ac30be6997..67682858370 100644
--- a/Userland/Libraries/LibMarkdown/List.cpp
+++ b/Userland/Libraries/LibMarkdown/List.cpp
@@ -13,7 +13,7 @@
 
 namespace Markdown {
 
-DeprecatedString List::render_to_html(bool) const
+ByteString List::render_to_html(bool) const
 {
     StringBuilder builder;
 
@@ -35,12 +35,12 @@ DeprecatedString List::render_to_html(bool) const
 
     builder.appendff("</{}>\n", tag);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-Vector<DeprecatedString> List::render_lines_for_terminal(size_t view_width) const
+Vector<ByteString> List::render_lines_for_terminal(size_t view_width) const
 {
-    Vector<DeprecatedString> lines;
+    Vector<ByteString> lines;
 
     int i = 0;
     for (auto& item : m_items) {
@@ -57,13 +57,13 @@ Vector<DeprecatedString> List::render_lines_for_terminal(size_t view_width) cons
 
         builder.append(first_line);
 
-        lines.append(builder.to_deprecated_string());
+        lines.append(builder.to_byte_string());
 
         for (auto& line : item_lines) {
             builder.clear();
-            builder.append(DeprecatedString::repeated(' ', item_indentation));
+            builder.append(ByteString::repeated(' ', item_indentation));
             builder.append(line);
-            lines.append(builder.to_deprecated_string());
+            lines.append(builder.to_byte_string());
         }
     }
 
diff --git a/Userland/Libraries/LibMarkdown/List.h b/Userland/Libraries/LibMarkdown/List.h
index 12779f4ad79..1ac888c584f 100644
--- a/Userland/Libraries/LibMarkdown/List.h
+++ b/Userland/Libraries/LibMarkdown/List.h
@@ -25,8 +25,8 @@ public:
     }
     virtual ~List() override = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const override;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const override;
+    virtual ByteString render_to_html(bool tight = false) const override;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const override;
     virtual RecursionDecision walk(Visitor&) const override;
 
     static OwnPtr<List> parse(LineIterator& lines);
diff --git a/Userland/Libraries/LibMarkdown/Paragraph.cpp b/Userland/Libraries/LibMarkdown/Paragraph.cpp
index 3ad5e509671..4110d26c590 100644
--- a/Userland/Libraries/LibMarkdown/Paragraph.cpp
+++ b/Userland/Libraries/LibMarkdown/Paragraph.cpp
@@ -11,7 +11,7 @@
 
 namespace Markdown {
 
-DeprecatedString Paragraph::render_to_html(bool tight) const
+ByteString Paragraph::render_to_html(bool tight) const
 {
     StringBuilder builder;
 
@@ -25,12 +25,12 @@ DeprecatedString Paragraph::render_to_html(bool tight) const
 
     builder.append('\n');
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-Vector<DeprecatedString> Paragraph::render_lines_for_terminal(size_t) const
+Vector<ByteString> Paragraph::render_lines_for_terminal(size_t) const
 {
-    return Vector<DeprecatedString> { DeprecatedString::formatted("  {}", m_text.render_for_terminal()), "" };
+    return Vector<ByteString> { ByteString::formatted("  {}", m_text.render_for_terminal()), "" };
 }
 
 RecursionDecision Paragraph::walk(Visitor& visitor) const
diff --git a/Userland/Libraries/LibMarkdown/Paragraph.h b/Userland/Libraries/LibMarkdown/Paragraph.h
index cad78a5e75b..ed2599b5bcb 100644
--- a/Userland/Libraries/LibMarkdown/Paragraph.h
+++ b/Userland/Libraries/LibMarkdown/Paragraph.h
@@ -22,8 +22,8 @@ public:
 
     virtual ~Paragraph() override = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const override;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const override;
+    virtual ByteString render_to_html(bool tight = false) const override;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const override;
     virtual RecursionDecision walk(Visitor&) const override;
 
 private:
diff --git a/Userland/Libraries/LibMarkdown/Table.cpp b/Userland/Libraries/LibMarkdown/Table.cpp
index d526e7acffa..d65dfdf69e8 100644
--- a/Userland/Libraries/LibMarkdown/Table.cpp
+++ b/Userland/Libraries/LibMarkdown/Table.cpp
@@ -12,11 +12,11 @@
 
 namespace Markdown {
 
-Vector<DeprecatedString> Table::render_lines_for_terminal(size_t view_width) const
+Vector<ByteString> Table::render_lines_for_terminal(size_t view_width) const
 {
     auto unit_width_length = view_width == 0 ? 4 : ((float)(view_width - m_columns.size()) / (float)m_total_width);
     StringBuilder builder;
-    Vector<DeprecatedString> lines;
+    Vector<ByteString> lines;
 
     auto write_aligned = [&](auto const& text, auto width, auto alignment) {
         size_t original_length = text.terminal_length();
@@ -44,12 +44,12 @@ Vector<DeprecatedString> Table::render_lines_for_terminal(size_t view_width) con
         write_aligned(col.header, width, col.alignment);
     }
 
-    lines.append(builder.to_deprecated_string());
+    lines.append(builder.to_byte_string());
     builder.clear();
 
     for (size_t i = 0; i < view_width; ++i)
         builder.append('-');
-    lines.append(builder.to_deprecated_string());
+    lines.append(builder.to_byte_string());
     builder.clear();
 
     for (size_t i = 0; i < m_row_count; ++i) {
@@ -65,7 +65,7 @@ Vector<DeprecatedString> Table::render_lines_for_terminal(size_t view_width) con
             size_t width = col.relative_width * unit_width_length;
             write_aligned(cell, width, col.alignment);
         }
-        lines.append(builder.to_deprecated_string());
+        lines.append(builder.to_byte_string());
         builder.clear();
     }
 
@@ -74,7 +74,7 @@ Vector<DeprecatedString> Table::render_lines_for_terminal(size_t view_width) con
     return lines;
 }
 
-DeprecatedString Table::render_to_html(bool) const
+ByteString Table::render_to_html(bool) const
 {
     auto alignment_string = [](Alignment alignment) {
         switch (alignment) {
@@ -114,7 +114,7 @@ DeprecatedString Table::render_to_html(bool) const
     builder.append("</tbody>"sv);
     builder.append("</table>"sv);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 RecursionDecision Table::walk(Visitor& visitor) const
diff --git a/Userland/Libraries/LibMarkdown/Table.h b/Userland/Libraries/LibMarkdown/Table.h
index 554f970f61e..a147ad015da 100644
--- a/Userland/Libraries/LibMarkdown/Table.h
+++ b/Userland/Libraries/LibMarkdown/Table.h
@@ -33,8 +33,8 @@ public:
     Table() = default;
     virtual ~Table() override = default;
 
-    virtual DeprecatedString render_to_html(bool tight = false) const override;
-    virtual Vector<DeprecatedString> render_lines_for_terminal(size_t view_width = 0) const override;
+    virtual ByteString render_to_html(bool tight = false) const override;
+    virtual Vector<ByteString> render_lines_for_terminal(size_t view_width = 0) const override;
     virtual RecursionDecision walk(Visitor&) const override;
     static OwnPtr<Table> parse(LineIterator& lines);
 
diff --git a/Userland/Libraries/LibMarkdown/Text.cpp b/Userland/Libraries/LibMarkdown/Text.cpp
index 1f5d92ad08c..365fa1f1cb9 100644
--- a/Userland/Libraries/LibMarkdown/Text.cpp
+++ b/Userland/Libraries/LibMarkdown/Text.cpp
@@ -298,25 +298,25 @@ size_t Text::terminal_length() const
     return m_node->terminal_length();
 }
 
-DeprecatedString Text::render_to_html() const
+ByteString Text::render_to_html() const
 {
     StringBuilder builder;
     m_node->render_to_html(builder);
-    return builder.to_deprecated_string().trim(" \n\t"sv);
+    return builder.to_byte_string().trim(" \n\t"sv);
 }
 
-DeprecatedString Text::render_for_raw_print() const
+ByteString Text::render_for_raw_print() const
 {
     StringBuilder builder;
     m_node->render_for_raw_print(builder);
-    return builder.to_deprecated_string().trim(" \n\t"sv);
+    return builder.to_byte_string().trim(" \n\t"sv);
 }
 
-DeprecatedString Text::render_for_terminal() const
+ByteString Text::render_for_terminal() const
 {
     StringBuilder builder;
     m_node->render_for_terminal(builder);
-    return builder.to_deprecated_string().trim(" \n\t"sv);
+    return builder.to_byte_string().trim(" \n\t"sv);
 }
 
 RecursionDecision Text::walk(Visitor& visitor) const
@@ -366,7 +366,7 @@ Vector<Text::Token> Text::tokenize(StringView str)
             return;
 
         tokens.append({
-            current_token.to_deprecated_string(),
+            current_token.to_byte_string(),
             left_flanking,
             right_flanking,
             punct_before,
@@ -671,11 +671,11 @@ NonnullOwnPtr<Text::Node> Text::parse_link(Vector<Token>::ConstIterator& tokens)
         if (*iterator == ")"sv) {
             tokens = iterator;
 
-            DeprecatedString href = address.to_deprecated_string().trim_whitespace();
+            ByteString href = address.to_byte_string().trim_whitespace();
 
             // Add file:// if the link is an absolute path otherwise it will be assumed relative.
             if (AK::StringUtils::starts_with(href, "/"sv, CaseSensitivity::CaseSensitive))
-                href = DeprecatedString::formatted("file://{}", href);
+                href = ByteString::formatted("file://{}", href);
 
             return make<LinkNode>(is_image, move(link_text), move(href), image_width, image_height);
         }
diff --git a/Userland/Libraries/LibMarkdown/Text.h b/Userland/Libraries/LibMarkdown/Text.h
index 40ee75198ac..eeb719b5a7a 100644
--- a/Userland/Libraries/LibMarkdown/Text.h
+++ b/Userland/Libraries/LibMarkdown/Text.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Noncopyable.h>
 #include <AK/OwnPtr.h>
 #include <AK/RecursionDecision.h>
@@ -75,7 +75,7 @@ public:
 
     class TextNode : public Node {
     public:
-        DeprecatedString text;
+        ByteString text;
         bool collapsible;
 
         TextNode(StringView text)
@@ -101,11 +101,11 @@ public:
     public:
         bool is_image;
         NonnullOwnPtr<Node> text;
-        DeprecatedString href;
+        ByteString href;
         Optional<int> image_width;
         Optional<int> image_height;
 
-        LinkNode(bool is_image, NonnullOwnPtr<Node> text, DeprecatedString href, Optional<int> image_width, Optional<int> image_height)
+        LinkNode(bool is_image, NonnullOwnPtr<Node> text, ByteString href, Optional<int> image_width, Optional<int> image_height)
             : is_image(is_image)
             , text(move(text))
             , href(move(href))
@@ -154,16 +154,16 @@ public:
 
     size_t terminal_length() const;
 
-    DeprecatedString render_to_html() const;
-    DeprecatedString render_for_terminal() const;
-    DeprecatedString render_for_raw_print() const;
+    ByteString render_to_html() const;
+    ByteString render_for_terminal() const;
+    ByteString render_for_raw_print() const;
     RecursionDecision walk(Visitor&) const;
 
     static Text parse(StringView);
 
 private:
     struct Token {
-        DeprecatedString data;
+        ByteString data;
         // Flanking basically means that a delimiter run has a non-whitespace,
         // non-punctuation character on the corresponding side. For a more exact
         // definition, see the CommonMark spec.
diff --git a/Userland/Libraries/LibMarkdown/Visitor.h b/Userland/Libraries/LibMarkdown/Visitor.h
index 3f4c730588d..14a33da9f4d 100644
--- a/Userland/Libraries/LibMarkdown/Visitor.h
+++ b/Userland/Libraries/LibMarkdown/Visitor.h
@@ -47,7 +47,7 @@ public:
     virtual RecursionDecision visit(Text::StrikeThroughNode const&) { return RecursionDecision::Recurse; }
     virtual RecursionDecision visit(Text::TextNode const&) { return RecursionDecision::Recurse; }
 
-    virtual RecursionDecision visit(DeprecatedString const&) { return RecursionDecision::Recurse; }
+    virtual RecursionDecision visit(ByteString const&) { return RecursionDecision::Recurse; }
 };
 
 }
diff --git a/Userland/Libraries/LibPCIDB/Database.cpp b/Userland/Libraries/LibPCIDB/Database.cpp
index 18705a5b20d..a51c9845c47 100644
--- a/Userland/Libraries/LibPCIDB/Database.cpp
+++ b/Userland/Libraries/LibPCIDB/Database.cpp
@@ -12,7 +12,7 @@
 
 namespace PCIDB {
 
-RefPtr<Database> Database::open(DeprecatedString const& filename)
+RefPtr<Database> Database::open(ByteString const& filename)
 {
     auto file_or_error = Core::MappedFile::map(filename);
     if (file_or_error.is_error())
diff --git a/Userland/Libraries/LibPCIDB/Database.h b/Userland/Libraries/LibPCIDB/Database.h
index fbc714b1ef8..72cef6b7211 100644
--- a/Userland/Libraries/LibPCIDB/Database.h
+++ b/Userland/Libraries/LibPCIDB/Database.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/RefCounted.h>
@@ -53,7 +53,7 @@ struct Class {
 
 class Database : public RefCounted<Database> {
 public:
-    static RefPtr<Database> open(DeprecatedString const& filename);
+    static RefPtr<Database> open(ByteString const& filename);
     static RefPtr<Database> open() { return open("/res/pci.ids"); }
 
     const StringView get_vendor(u16 vendor_id) const;
diff --git a/Userland/Libraries/LibPDF/ColorSpace.cpp b/Userland/Libraries/LibPDF/ColorSpace.cpp
index 46a54892d21..c420f4e002f 100644
--- a/Userland/Libraries/LibPDF/ColorSpace.cpp
+++ b/Userland/Libraries/LibPDF/ColorSpace.cpp
@@ -164,7 +164,7 @@ PDFErrorOr<NonnullRefPtr<DeviceNColorSpace>> DeviceNColorSpace::create(Document*
     // "The names parameter is an array of name objects specifying the individual color components.
     //  The length of the array determines the number of components in the DeviceN color space"
     auto names_array = TRY(document->resolve_to<ArrayObject>(parameters[0]));
-    Vector<DeprecatedString> names;
+    Vector<ByteString> names;
     for (size_t i = 0; i < names_array->size(); ++i)
         names.append(names_array->get_name_at(i)->name());
 
diff --git a/Userland/Libraries/LibPDF/ColorSpace.h b/Userland/Libraries/LibPDF/ColorSpace.h
index 4ba6dea891c..61431e69c69 100644
--- a/Userland/Libraries/LibPDF/ColorSpace.h
+++ b/Userland/Libraries/LibPDF/ColorSpace.h
@@ -131,7 +131,7 @@ public:
 private:
     DeviceNColorSpace(NonnullRefPtr<ColorSpace>, NonnullRefPtr<Function>);
 
-    Vector<DeprecatedString> m_names;
+    Vector<ByteString> m_names;
     NonnullRefPtr<ColorSpace> m_alternate_space;
     NonnullRefPtr<Function> m_tint_transform;
     Vector<float> mutable m_tint_input_values;
@@ -247,7 +247,7 @@ public:
 private:
     SeparationColorSpace(NonnullRefPtr<ColorSpace>, NonnullRefPtr<Function>);
 
-    DeprecatedString m_name;
+    ByteString m_name;
     NonnullRefPtr<ColorSpace> m_alternate_space;
     NonnullRefPtr<Function> m_tint_transform;
     Vector<Value> mutable m_tint_output_values;
diff --git a/Userland/Libraries/LibPDF/Document.cpp b/Userland/Libraries/LibPDF/Document.cpp
index 995e8529bc4..9137cb0fe47 100644
--- a/Userland/Libraries/LibPDF/Document.cpp
+++ b/Userland/Libraries/LibPDF/Document.cpp
@@ -11,14 +11,14 @@
 
 namespace PDF {
 
-DeprecatedString OutlineItem::to_deprecated_string(int indent) const
+ByteString OutlineItem::to_byte_string(int indent) const
 {
-    auto indent_str = DeprecatedString::repeated("  "sv, indent + 1);
+    auto indent_str = ByteString::repeated("  "sv, indent + 1);
 
     StringBuilder child_builder;
     child_builder.append('[');
     for (auto& child : children)
-        child_builder.appendff("{}\n", child->to_deprecated_string(indent + 1));
+        child_builder.appendff("{}\n", child->to_byte_string(indent + 1));
     child_builder.appendff("{}]", indent_str);
 
     StringBuilder builder;
@@ -29,62 +29,62 @@ DeprecatedString OutlineItem::to_deprecated_string(int indent) const
     builder.appendff("{}color={}\n", indent_str, color);
     builder.appendff("{}italic={}\n", indent_str, italic);
     builder.appendff("{}bold={}\n", indent_str, bold);
-    builder.appendff("{}children={}\n", indent_str, child_builder.to_deprecated_string());
-    builder.appendff("{}}}", DeprecatedString::repeated("  "sv, indent));
+    builder.appendff("{}children={}\n", indent_str, child_builder.to_byte_string());
+    builder.appendff("{}}}", ByteString::repeated("  "sv, indent));
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-PDFErrorOr<Optional<DeprecatedString>> InfoDict::title() const
+PDFErrorOr<Optional<ByteString>> InfoDict::title() const
 {
     return get_text(CommonNames::Title);
 }
 
-PDFErrorOr<Optional<DeprecatedString>> InfoDict::author() const
+PDFErrorOr<Optional<ByteString>> InfoDict::author() const
 {
     return get_text(CommonNames::Author);
 }
 
-PDFErrorOr<Optional<DeprecatedString>> InfoDict::subject() const
+PDFErrorOr<Optional<ByteString>> InfoDict::subject() const
 {
     return get_text(CommonNames::Subject);
 }
 
-PDFErrorOr<Optional<DeprecatedString>> InfoDict::keywords() const
+PDFErrorOr<Optional<ByteString>> InfoDict::keywords() const
 {
     return get_text(CommonNames::Keywords);
 }
 
-PDFErrorOr<Optional<DeprecatedString>> InfoDict::creator() const
+PDFErrorOr<Optional<ByteString>> InfoDict::creator() const
 {
     return get_text(CommonNames::Creator);
 }
 
-PDFErrorOr<Optional<DeprecatedString>> InfoDict::producer() const
+PDFErrorOr<Optional<ByteString>> InfoDict::producer() const
 {
     return get_text(CommonNames::Producer);
 }
 
-PDFErrorOr<Optional<DeprecatedString>> InfoDict::creation_date() const
+PDFErrorOr<Optional<ByteString>> InfoDict::creation_date() const
 {
     return get(CommonNames::CreationDate);
 }
 
-PDFErrorOr<Optional<DeprecatedString>> InfoDict::modification_date() const
+PDFErrorOr<Optional<ByteString>> InfoDict::modification_date() const
 {
     return get(CommonNames::ModDate);
 }
 
-PDFErrorOr<Optional<DeprecatedString>> InfoDict::get_text(DeprecatedFlyString const& name) const
+PDFErrorOr<Optional<ByteString>> InfoDict::get_text(DeprecatedFlyString const& name) const
 {
     return TRY(get(name)).map(Document::text_string_to_utf8);
 }
 
-DeprecatedString Document::text_string_to_utf8(DeprecatedString const& text_string)
+ByteString Document::text_string_to_utf8(ByteString const& text_string)
 {
     if (text_string.bytes().starts_with(Array<u8, 2> { 0xfe, 0xff })) {
         // The string is encoded in UTF16-BE
-        return TextCodec::decoder_for("utf-16be"sv)->to_utf8(text_string).release_value_but_fixme_should_propagate_errors().to_deprecated_string();
+        return TextCodec::decoder_for("utf-16be"sv)->to_utf8(text_string).release_value_but_fixme_should_propagate_errors().to_byte_string();
     }
 
     if (text_string.bytes().starts_with(Array<u8, 3> { 239, 187, 191 })) {
@@ -92,7 +92,7 @@ DeprecatedString Document::text_string_to_utf8(DeprecatedString const& text_stri
         return text_string.substring(3);
     }
 
-    return TextCodec::decoder_for("PDFDocEncoding"sv)->to_utf8(text_string).release_value_but_fixme_should_propagate_errors().to_deprecated_string();
+    return TextCodec::decoder_for("PDFDocEncoding"sv)->to_utf8(text_string).release_value_but_fixme_should_propagate_errors().to_byte_string();
 }
 
 PDFErrorOr<NonnullRefPtr<Document>> Document::create(ReadonlyBytes bytes)
@@ -197,7 +197,7 @@ static PDFErrorOr<void> dump_tree(Document& document, size_t index, HashTable<in
 
     auto const& value = TRY(document.get_or_load_value(index));
     outln("{} 0 obj", index);
-    outln("{}", value.to_deprecated_string(0));
+    outln("{}", value.to_byte_string(0));
     outln("endobj");
 
     Vector<int> referenced_indices;
@@ -392,7 +392,7 @@ PDFErrorOr<NonnullRefPtr<Object>> Document::find_in_name_tree_nodes(NonnullRefPt
             return find_in_name_tree(sibling, name);
         }
     }
-    return Error { Error::Type::MalformedPDF, DeprecatedString::formatted("Didn't find node in name tree containing name {}", name) };
+    return Error { Error::Type::MalformedPDF, ByteString::formatted("Didn't find node in name tree containing name {}", name) };
 }
 
 PDFErrorOr<NonnullRefPtr<Object>> Document::find_in_key_value_array(NonnullRefPtr<ArrayObject> key_value_array, DeprecatedFlyString name)
@@ -405,7 +405,7 @@ PDFErrorOr<NonnullRefPtr<Object>> Document::find_in_key_value_array(NonnullRefPt
             return key_value_array->get_object_at(this, 2 * i + 1);
         }
     }
-    return Error { Error::Type::MalformedPDF, DeprecatedString::formatted("Didn't find expected name {} in key/value array", name) };
+    return Error { Error::Type::MalformedPDF, ByteString::formatted("Didn't find expected name {} in key/value array", name) };
 }
 
 PDFErrorOr<void> Document::build_outline()
diff --git a/Userland/Libraries/LibPDF/Document.h b/Userland/Libraries/LibPDF/Document.h
index 39fb571fad2..7b2f90cf66b 100644
--- a/Userland/Libraries/LibPDF/Document.h
+++ b/Userland/Libraries/LibPDF/Document.h
@@ -40,7 +40,7 @@ struct OutlineItem final : public RefCounted<OutlineItem>
     , public Weakable<OutlineItem> {
     WeakPtr<OutlineItem> parent;
     Vector<NonnullRefPtr<OutlineItem>> children;
-    DeprecatedString title; // Already converted to UTF-8.
+    ByteString title; // Already converted to UTF-8.
     i32 count { 0 };
     Destination dest;
     Gfx::Color color { Color::NamedColor::Black }; // 'C' in the PDF spec
@@ -49,7 +49,7 @@ struct OutlineItem final : public RefCounted<OutlineItem>
 
     OutlineItem() = default;
 
-    DeprecatedString to_deprecated_string(int indent) const;
+    ByteString to_byte_string(int indent) const;
 };
 
 struct OutlineDict final : public RefCounted<OutlineDict> {
@@ -69,30 +69,30 @@ public:
 
     // These all return strings that are already converted to UTF-8.
 
-    PDFErrorOr<Optional<DeprecatedString>> title() const;
-    PDFErrorOr<Optional<DeprecatedString>> author() const;
-    PDFErrorOr<Optional<DeprecatedString>> subject() const;
-    PDFErrorOr<Optional<DeprecatedString>> keywords() const;
+    PDFErrorOr<Optional<ByteString>> title() const;
+    PDFErrorOr<Optional<ByteString>> author() const;
+    PDFErrorOr<Optional<ByteString>> subject() const;
+    PDFErrorOr<Optional<ByteString>> keywords() const;
 
     // Name of the program that created the original, non-PDF file.
-    PDFErrorOr<Optional<DeprecatedString>> creator() const;
+    PDFErrorOr<Optional<ByteString>> creator() const;
 
     // Name of the program that converted the file to PDF.
-    PDFErrorOr<Optional<DeprecatedString>> producer() const;
+    PDFErrorOr<Optional<ByteString>> producer() const;
 
     // FIXME: Provide some helper for parsing the date strings returned by these two methods.
-    PDFErrorOr<Optional<DeprecatedString>> creation_date() const;
-    PDFErrorOr<Optional<DeprecatedString>> modification_date() const;
+    PDFErrorOr<Optional<ByteString>> creation_date() const;
+    PDFErrorOr<Optional<ByteString>> modification_date() const;
 
 private:
-    PDFErrorOr<Optional<DeprecatedString>> get(DeprecatedFlyString const& name) const
+    PDFErrorOr<Optional<ByteString>> get(DeprecatedFlyString const& name) const
     {
         if (!m_info_dict->contains(name))
             return OptionalNone {};
         return TRY(m_info_dict->get_string(m_document, name))->string();
     }
 
-    PDFErrorOr<Optional<DeprecatedString>> get_text(DeprecatedFlyString const& name) const;
+    PDFErrorOr<Optional<ByteString>> get_text(DeprecatedFlyString const& name) const;
 
     WeakPtr<Document> m_document;
     NonnullRefPtr<DictObject> m_info_dict;
@@ -103,7 +103,7 @@ class Document final
     , public Weakable<Document> {
 public:
     // Converts a text string (PDF 1.7 spec, 3.8.1. "String Types") to UTF-8.
-    static DeprecatedString text_string_to_utf8(DeprecatedString const&);
+    static ByteString text_string_to_utf8(ByteString const&);
 
     static PDFErrorOr<NonnullRefPtr<Document>> create(ReadonlyBytes bytes);
 
@@ -254,7 +254,7 @@ template<>
 struct Formatter<PDF::OutlineItem> : Formatter<FormatString> {
     ErrorOr<void> format(FormatBuilder& builder, PDF::OutlineItem const& item)
     {
-        return builder.put_string(item.to_deprecated_string(0));
+        return builder.put_string(item.to_byte_string(0));
     }
 };
 
@@ -265,11 +265,11 @@ struct Formatter<PDF::OutlineDict> : Formatter<FormatString> {
         StringBuilder child_builder;
         child_builder.append('[');
         for (auto& child : dict.children)
-            child_builder.appendff("{}\n", child->to_deprecated_string(2));
+            child_builder.appendff("{}\n", child->to_byte_string(2));
         child_builder.append("  ]"sv);
 
         return Formatter<FormatString>::format(builder,
-            "OutlineDict {{\n  count={}\n  children={}\n}}"sv, dict.count, child_builder.to_deprecated_string());
+            "OutlineDict {{\n  count={}\n  children={}\n}}"sv, dict.count, child_builder.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/DocumentParser.cpp b/Userland/Libraries/LibPDF/DocumentParser.cpp
index ee13f0d7c53..d147d854d5c 100644
--- a/Userland/Libraries/LibPDF/DocumentParser.cpp
+++ b/Userland/Libraries/LibPDF/DocumentParser.cpp
@@ -482,12 +482,12 @@ PDFErrorOr<NonnullRefPtr<XRefTable>> DocumentParser::parse_xref_table()
         auto object_count = object_count_value.get<int>();
 
         for (int i = 0; i < object_count; i++) {
-            auto offset_string = DeprecatedString(m_reader.bytes().slice(m_reader.offset(), 10));
+            auto offset_string = ByteString(m_reader.bytes().slice(m_reader.offset(), 10));
             m_reader.move_by(10);
             if (!m_reader.consume(' '))
                 return error("Malformed xref entry");
 
-            auto generation_string = DeprecatedString(m_reader.bytes().slice(m_reader.offset(), 5));
+            auto generation_string = ByteString(m_reader.bytes().slice(m_reader.offset(), 5));
             m_reader.move_by(5);
             if (!m_reader.consume(' '))
                 return error("Malformed xref entry");
@@ -747,7 +747,7 @@ PDFErrorOr<RefPtr<DictObject>> DocumentParser::conditionally_parse_page_tree_nod
     auto dict_value = TRY(parse_object_with_index(object_index));
     auto dict_object = dict_value.get<NonnullRefPtr<Object>>();
     if (!dict_object->is<DictObject>())
-        return error(DeprecatedString::formatted("Invalid page tree with xref index {}", object_index));
+        return error(ByteString::formatted("Invalid page tree with xref index {}", object_index));
 
     auto dict = dict_object->cast<DictObject>();
     if (!dict->contains_any_of(CommonNames::Type, CommonNames::Parent, CommonNames::Kids, CommonNames::Count))
@@ -787,7 +787,7 @@ struct Formatter<PDF::DocumentParser::LinearizationDictionary> : Formatter<Strin
         builder.appendff("  offset_of_main_xref_table={}\n", dict.offset_of_main_xref_table);
         builder.appendff("  first_page={}\n", dict.first_page);
         builder.append('}');
-        return Formatter<StringView>::format(format_builder, builder.to_deprecated_string());
+        return Formatter<StringView>::format(format_builder, builder.to_byte_string());
     }
 };
 
@@ -811,7 +811,7 @@ struct Formatter<PDF::DocumentParser::PageOffsetHintTable> : Formatter<StringVie
         builder.appendff("  bits_required_for_fraction_numerator={}\n", table.bits_required_for_fraction_numerator);
         builder.appendff("  shared_object_reference_fraction_denominator={}\n", table.shared_object_reference_fraction_denominator);
         builder.append('}');
-        return Formatter<StringView>::format(format_builder, builder.to_deprecated_string());
+        return Formatter<StringView>::format(format_builder, builder.to_byte_string());
     }
 };
 
@@ -835,7 +835,7 @@ struct Formatter<PDF::DocumentParser::PageOffsetHintTableEntry> : Formatter<Stri
         builder.appendff("  page_content_stream_offset_number={}\n", entry.page_content_stream_offset_number);
         builder.appendff("  page_content_stream_length_number={}\n", entry.page_content_stream_length_number);
         builder.append('}');
-        return Formatter<StringView>::format(format_builder, builder.to_deprecated_string());
+        return Formatter<StringView>::format(format_builder, builder.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/Encoding.cpp b/Userland/Libraries/LibPDF/Encoding.cpp
index 79ff2dd4d45..95f7b364ef6 100644
--- a/Userland/Libraries/LibPDF/Encoding.cpp
+++ b/Userland/Libraries/LibPDF/Encoding.cpp
@@ -164,7 +164,7 @@ NonnullRefPtr<Encoding> Encoding::zapf_encoding()
     return encoding;
 }
 
-u16 Encoding::get_char_code(DeprecatedString const& name) const
+u16 Encoding::get_char_code(ByteString const& name) const
 {
     auto code_iterator = m_name_mapping.find(name);
     if (code_iterator != m_name_mapping.end())
diff --git a/Userland/Libraries/LibPDF/Encoding.h b/Userland/Libraries/LibPDF/Encoding.h
index 0116867130d..ac071639a4b 100644
--- a/Userland/Libraries/LibPDF/Encoding.h
+++ b/Userland/Libraries/LibPDF/Encoding.h
@@ -638,16 +638,16 @@ public:
     static NonnullRefPtr<Encoding> symbol_encoding();
     static NonnullRefPtr<Encoding> zapf_encoding();
 
-    HashMap<DeprecatedString, CharCodeType> const& name_mapping() const { return m_name_mapping; }
+    HashMap<ByteString, CharCodeType> const& name_mapping() const { return m_name_mapping; }
 
-    u16 get_char_code(DeprecatedString const&) const;
+    u16 get_char_code(ByteString const&) const;
     DeprecatedFlyString get_name(u8 char_code) const;
 
     void set(CharCodeType char_code, DeprecatedFlyString const& glyph_name);
 
 protected:
     HashMap<CharCodeType, DeprecatedFlyString> m_descriptors;
-    HashMap<DeprecatedString, CharCodeType> m_name_mapping;
+    HashMap<ByteString, CharCodeType> m_name_mapping;
 
     bool m_windows { false };
 };
diff --git a/Userland/Libraries/LibPDF/Encryption.cpp b/Userland/Libraries/LibPDF/Encryption.cpp
index f76359035fe..d0e6576f8e2 100644
--- a/Userland/Libraries/LibPDF/Encryption.cpp
+++ b/Userland/Libraries/LibPDF/Encryption.cpp
@@ -67,7 +67,7 @@ struct CryptFilter {
     int length_in_bits { 0 };
 };
 
-static PDFErrorOr<CryptFilter> parse_v4_or_newer_crypt(Document* document, NonnullRefPtr<DictObject> encryption_dict, DeprecatedString filter)
+static PDFErrorOr<CryptFilter> parse_v4_or_newer_crypt(Document* document, NonnullRefPtr<DictObject> encryption_dict, ByteString filter)
 {
     // See 3.5 Encryption, Table 3.18 "Entries common to all encryption dictionaries" for StmF and StrF,
     // and 3.5.4 Crypt Filters in the 1.7 spec, in particular Table 3.22 "Entries common to all crypt filter dictionaries".
@@ -139,11 +139,11 @@ PDFErrorOr<NonnullRefPtr<StandardSecurityHandler>> StandardSecurityHandler::crea
 
     if (v >= 4) {
         // "Default value: Identity"
-        DeprecatedString stream_filter = "Identity";
+        ByteString stream_filter = "Identity";
         if (encryption_dict->contains(CommonNames::StmF))
             stream_filter = TRY(encryption_dict->get_name(document, CommonNames::StmF))->name();
 
-        DeprecatedString string_filter = "Identity";
+        ByteString string_filter = "Identity";
         if (encryption_dict->contains(CommonNames::StrF))
             string_filter = TRY(encryption_dict->get_name(document, CommonNames::StrF))->name();
 
@@ -166,7 +166,7 @@ PDFErrorOr<NonnullRefPtr<StandardSecurityHandler>> StandardSecurityHandler::crea
     if (encryption_dict->contains(CommonNames::EncryptMetadata))
         encryption_dict->get_value(CommonNames::EncryptMetadata).get<bool>();
 
-    DeprecatedString oe, ue, perms;
+    ByteString oe, ue, perms;
     if (v >= 5) {
         oe = TRY(encryption_dict->get_string(document, CommonNames::OE))->string();
         ue = TRY(encryption_dict->get_string(document, CommonNames::UE))->string();
@@ -193,7 +193,7 @@ PDFErrorOr<NonnullRefPtr<StandardSecurityHandler>> StandardSecurityHandler::crea
     return adopt_ref(*new StandardSecurityHandler(document, revision, o, oe, u, ue, perms, p, encrypt_metadata, length, method));
 }
 
-StandardSecurityHandler::StandardSecurityHandler(Document* document, size_t revision, DeprecatedString const& o_entry, DeprecatedString const& oe_entry, DeprecatedString const& u_entry, DeprecatedString const& ue_entry, DeprecatedString const& perms_entry, u32 flags, bool encrypt_metadata, size_t length, CryptFilterMethod method)
+StandardSecurityHandler::StandardSecurityHandler(Document* document, size_t revision, ByteString const& o_entry, ByteString const& oe_entry, ByteString const& u_entry, ByteString const& ue_entry, ByteString const& perms_entry, u32 flags, bool encrypt_metadata, size_t length, CryptFilterMethod method)
     : m_document(document)
     , m_revision(revision)
     , m_o_entry(o_entry)
@@ -686,7 +686,7 @@ void StandardSecurityHandler::crypt(NonnullRefPtr<Object> object, Reference refe
         auto string = object->cast<StringObject>();
         bytes = string->string().bytes();
         assign = [&object](ByteBuffer buffer) {
-            object->cast<StringObject>()->set_string(DeprecatedString(buffer.bytes()));
+            object->cast<StringObject>()->set_string(ByteString(buffer.bytes()));
         };
     } else {
         VERIFY_NOT_REACHED();
diff --git a/Userland/Libraries/LibPDF/Encryption.h b/Userland/Libraries/LibPDF/Encryption.h
index 6d627c390bd..cf3dede12a6 100644
--- a/Userland/Libraries/LibPDF/Encryption.h
+++ b/Userland/Libraries/LibPDF/Encryption.h
@@ -39,7 +39,7 @@ class StandardSecurityHandler : public SecurityHandler {
 public:
     static PDFErrorOr<NonnullRefPtr<StandardSecurityHandler>> create(Document*, NonnullRefPtr<DictObject> encryption_dict);
 
-    StandardSecurityHandler(Document*, size_t revision, DeprecatedString const& o_entry, DeprecatedString const& oe_entry, DeprecatedString const& u_entry, DeprecatedString const& ue_entry, DeprecatedString const& perms, u32 flags, bool encrypt_metadata, size_t length, CryptFilterMethod method);
+    StandardSecurityHandler(Document*, size_t revision, ByteString const& o_entry, ByteString const& oe_entry, ByteString const& u_entry, ByteString const& ue_entry, ByteString const& perms, u32 flags, bool encrypt_metadata, size_t length, CryptFilterMethod method);
 
     ~StandardSecurityHandler() override = default;
 
@@ -73,11 +73,11 @@ private:
     Document* m_document;
     size_t m_revision;
     Optional<ByteBuffer> m_encryption_key;
-    DeprecatedString m_o_entry;
-    DeprecatedString m_oe_entry;
-    DeprecatedString m_u_entry;
-    DeprecatedString m_ue_entry;
-    DeprecatedString m_perms_entry;
+    ByteString m_o_entry;
+    ByteString m_oe_entry;
+    ByteString m_u_entry;
+    ByteString m_ue_entry;
+    ByteString m_perms_entry;
     u32 m_flags;
     bool m_encrypt_metadata;
     size_t m_length;
diff --git a/Userland/Libraries/LibPDF/Error.h b/Userland/Libraries/LibPDF/Error.h
index 9ddc7a7684e..d4a8f640d9b 100644
--- a/Userland/Libraries/LibPDF/Error.h
+++ b/Userland/Libraries/LibPDF/Error.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/String.h>
 #include <AK/Vector.h>
 
@@ -23,12 +23,12 @@ public:
 
     Error(AK::Error error)
         : m_type(Type::Internal)
-        , m_message(DeprecatedString::formatted("Internal error while processing PDF file: {}", error.string_literal()))
+        , m_message(ByteString::formatted("Internal error while processing PDF file: {}", error.string_literal()))
     {
     }
 
-    Error(Type type, DeprecatedString const& message)
-        : Error(type, String::from_deprecated_string(message).release_value_but_fixme_should_propagate_errors())
+    Error(Type type, ByteString const& message)
+        : Error(type, String::from_byte_string(message).release_value_but_fixme_should_propagate_errors())
     {
     }
 
@@ -37,22 +37,22 @@ public:
     {
         switch (type) {
         case Type::Parse:
-            m_message = DeprecatedString::formatted("Failed to parse PDF file: {}", message);
+            m_message = ByteString::formatted("Failed to parse PDF file: {}", message);
             break;
         case Type::Internal:
-            m_message = DeprecatedString::formatted("Internal error while processing PDF file: {}", message);
+            m_message = ByteString::formatted("Internal error while processing PDF file: {}", message);
             break;
         case Type::MalformedPDF:
-            m_message = DeprecatedString::formatted("Malformed PDF file: {}", message);
+            m_message = ByteString::formatted("Malformed PDF file: {}", message);
             break;
         case Type::RenderingUnsupported:
-            m_message = DeprecatedString::formatted("Rendering of feature not supported: {}", message);
+            m_message = ByteString::formatted("Rendering of feature not supported: {}", message);
             break;
         }
     }
 
     Type type() const { return m_type; }
-    DeprecatedString const& message() const { return m_message; }
+    ByteString const& message() const { return m_message; }
 
 #define DEFINE_STATIC_ERROR_FUNCTIONS(name, type)                                                           \
     static Error name##_error(StringView message)                                                           \
@@ -73,7 +73,7 @@ public:
 
 private:
     Type m_type;
-    DeprecatedString m_message;
+    ByteString m_message;
 
     static Error maybe_with_string(Type type, ErrorOr<String> maybe_string)
     {
diff --git a/Userland/Libraries/LibPDF/Fonts/CFF.cpp b/Userland/Libraries/LibPDF/Fonts/CFF.cpp
index 7b6898f5069..ba850c58829 100644
--- a/Userland/Libraries/LibPDF/Fonts/CFF.cpp
+++ b/Userland/Libraries/LibPDF/Fonts/CFF.cpp
@@ -812,7 +812,7 @@ PDFErrorOr<Vector<u8>> CFF::parse_encoding(Reader&& reader, HashMap<Card8, SID>&
                 TRY(encoding_codes.try_append(code));
         }
     } else
-        return error(DeprecatedString::formatted("Invalid encoding format: {}", format));
+        return error(ByteString::formatted("Invalid encoding format: {}", format));
 
     if (format_raw & 0x80) {
         // CFF spec, "Table 14 Supplemental Encoding Data"
@@ -975,6 +975,6 @@ PDFErrorOr<CFF::DictOperand> CFF::load_dict_operand(u8 b0, Reader& reader)
         return load_float_dict_operand(reader);
     if (b0 >= 28)
         return load_int_dict_operand(b0, reader);
-    return Error { Error::Type::MalformedPDF, DeprecatedString::formatted("Unknown CFF dict element prefix: {}", b0) };
+    return Error { Error::Type::MalformedPDF, ByteString::formatted("Unknown CFF dict element prefix: {}", b0) };
 }
 }
diff --git a/Userland/Libraries/LibPDF/Fonts/PDFFont.h b/Userland/Libraries/LibPDF/Fonts/PDFFont.h
index bed0cb3c0dd..722bf139006 100644
--- a/Userland/Libraries/LibPDF/Fonts/PDFFont.h
+++ b/Userland/Libraries/LibPDF/Fonts/PDFFont.h
@@ -23,7 +23,7 @@ public:
     virtual ~PDFFont() = default;
 
     virtual void set_font_size(float font_size) = 0;
-    virtual PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, DeprecatedString const&, Renderer const&) = 0;
+    virtual PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&, Renderer const&) = 0;
 
 protected:
     virtual PDFErrorOr<void> initialize(Document* document, NonnullRefPtr<DictObject> const& dict, float font_size);
diff --git a/Userland/Libraries/LibPDF/Fonts/PS1FontProgram.cpp b/Userland/Libraries/LibPDF/Fonts/PS1FontProgram.cpp
index fd6623b2858..17a3f6713e4 100644
--- a/Userland/Libraries/LibPDF/Fonts/PS1FontProgram.cpp
+++ b/Userland/Libraries/LibPDF/Fonts/PS1FontProgram.cpp
@@ -167,7 +167,7 @@ PDFErrorOr<Vector<float>> PS1FontProgram::parse_number_array(Reader& reader, siz
     return array;
 }
 
-PDFErrorOr<DeprecatedString> PS1FontProgram::parse_word(Reader& reader)
+PDFErrorOr<ByteString> PS1FontProgram::parse_word(Reader& reader)
 {
     reader.consume_whitespace();
 
@@ -186,7 +186,7 @@ PDFErrorOr<DeprecatedString> PS1FontProgram::parse_word(Reader& reader)
 PDFErrorOr<float> PS1FontProgram::parse_float(Reader& reader)
 {
     auto word = TRY(parse_word(reader));
-    return strtof(DeprecatedString(word).characters(), nullptr);
+    return strtof(ByteString(word).characters(), nullptr);
 }
 
 PDFErrorOr<int> PS1FontProgram::parse_int(Reader& reader)
@@ -216,7 +216,7 @@ PDFErrorOr<ByteBuffer> PS1FontProgram::decrypt(ReadonlyBytes const& encrypted, u
     return decrypted;
 }
 
-bool PS1FontProgram::seek_name(Reader& reader, DeprecatedString const& name)
+bool PS1FontProgram::seek_name(Reader& reader, ByteString const& name)
 {
     auto start = reader.offset();
 
diff --git a/Userland/Libraries/LibPDF/Fonts/PS1FontProgram.h b/Userland/Libraries/LibPDF/Fonts/PS1FontProgram.h
index df80e76a490..96198a1622f 100644
--- a/Userland/Libraries/LibPDF/Fonts/PS1FontProgram.h
+++ b/Userland/Libraries/LibPDF/Fonts/PS1FontProgram.h
@@ -26,12 +26,12 @@ private:
     PDFErrorOr<void> parse_encrypted_portion(ByteBuffer const&);
     PDFErrorOr<Vector<ByteBuffer>> parse_subroutines(Reader&) const;
     static PDFErrorOr<Vector<float>> parse_number_array(Reader&, size_t length);
-    static PDFErrorOr<DeprecatedString> parse_word(Reader&);
+    static PDFErrorOr<ByteString> parse_word(Reader&);
     static PDFErrorOr<float> parse_float(Reader&);
     static PDFErrorOr<int> parse_int(Reader&);
 
     static PDFErrorOr<ByteBuffer> decrypt(ReadonlyBytes const&, u16 key, size_t skip);
-    static bool seek_name(Reader&, DeprecatedString const&);
+    static bool seek_name(Reader&, ByteString const&);
 
     u16 m_encryption_key { 4330 };
     int m_lenIV { 4 };
diff --git a/Userland/Libraries/LibPDF/Fonts/SimpleFont.cpp b/Userland/Libraries/LibPDF/Fonts/SimpleFont.cpp
index 1f1846460b1..060e334922a 100644
--- a/Userland/Libraries/LibPDF/Fonts/SimpleFont.cpp
+++ b/Userland/Libraries/LibPDF/Fonts/SimpleFont.cpp
@@ -46,7 +46,7 @@ PDFErrorOr<void> SimpleFont::initialize(Document* document, NonnullRefPtr<DictOb
     return {};
 }
 
-PDFErrorOr<Gfx::FloatPoint> SimpleFont::draw_string(Gfx::Painter& painter, Gfx::FloatPoint glyph_position, DeprecatedString const& string, Renderer const& renderer)
+PDFErrorOr<Gfx::FloatPoint> SimpleFont::draw_string(Gfx::Painter& painter, Gfx::FloatPoint glyph_position, ByteString const& string, Renderer const& renderer)
 {
     auto const& text_rendering_matrix = renderer.calculate_text_rendering_matrix();
     auto font_size = text_rendering_matrix.x_scale() * renderer.text_state().font_size;
diff --git a/Userland/Libraries/LibPDF/Fonts/SimpleFont.h b/Userland/Libraries/LibPDF/Fonts/SimpleFont.h
index df9fccef5fc..e5b767b0f6b 100644
--- a/Userland/Libraries/LibPDF/Fonts/SimpleFont.h
+++ b/Userland/Libraries/LibPDF/Fonts/SimpleFont.h
@@ -13,7 +13,7 @@ namespace PDF {
 
 class SimpleFont : public PDFFont {
 public:
-    PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, DeprecatedString const&, Renderer const&) override;
+    PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&, Renderer const&) override;
 
 protected:
     PDFErrorOr<void> initialize(Document* document, NonnullRefPtr<DictObject> const& dict, float font_size) override;
diff --git a/Userland/Libraries/LibPDF/Fonts/Type0Font.cpp b/Userland/Libraries/LibPDF/Fonts/Type0Font.cpp
index ecb953caef6..62b8143339d 100644
--- a/Userland/Libraries/LibPDF/Fonts/Type0Font.cpp
+++ b/Userland/Libraries/LibPDF/Fonts/Type0Font.cpp
@@ -13,15 +13,15 @@ namespace PDF {
 class CIDFontType {
 public:
     virtual ~CIDFontType() = default;
-    virtual PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, DeprecatedString const&) = 0;
+    virtual PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&) = 0;
 };
 
 class CIDFontType0 : public CIDFontType {
 public:
-    PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, DeprecatedString const&) override;
+    PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&) override;
 };
 
-PDFErrorOr<Gfx::FloatPoint> CIDFontType0::draw_string(Gfx::Painter&, Gfx::FloatPoint, DeprecatedString const&)
+PDFErrorOr<Gfx::FloatPoint> CIDFontType0::draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&)
 {
     // ISO 32000 (PDF 2.0) 9.7.4.2 Glyph selection in CIDFonts
     // "When the CIDFont contains an embedded font program that is represented in the Compact Font Format (CFF),
@@ -39,7 +39,7 @@ class CIDFontType2 : public CIDFontType {
 public:
     static PDFErrorOr<NonnullOwnPtr<CIDFontType2>> create(Document*, NonnullRefPtr<DictObject> const& descendant, float font_size);
 
-    PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, DeprecatedString const&) override;
+    PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&) override;
 };
 
 PDFErrorOr<NonnullOwnPtr<CIDFontType2>> CIDFontType2::create(Document* document, NonnullRefPtr<DictObject> const& descendant, float font_size)
@@ -70,7 +70,7 @@ PDFErrorOr<NonnullOwnPtr<CIDFontType2>> CIDFontType2::create(Document* document,
     return TRY(adopt_nonnull_own_or_enomem(new (nothrow) CIDFontType2()));
 }
 
-PDFErrorOr<Gfx::FloatPoint> CIDFontType2::draw_string(Gfx::Painter&, Gfx::FloatPoint, DeprecatedString const&)
+PDFErrorOr<Gfx::FloatPoint> CIDFontType2::draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&)
 {
     // ISO 32000 (PDF 2.0) 9.7.4.2 Glyph selection in CIDFonts
     // "For Type 2, the CIDFont program is actually a TrueType font program, which has no native notion of CIDs.
@@ -175,7 +175,7 @@ void Type0Font::set_font_size(float)
 {
 }
 
-PDFErrorOr<Gfx::FloatPoint> Type0Font::draw_string(Gfx::Painter& painter, Gfx::FloatPoint glyph_position, DeprecatedString const& string, Renderer const&)
+PDFErrorOr<Gfx::FloatPoint> Type0Font::draw_string(Gfx::Painter& painter, Gfx::FloatPoint glyph_position, ByteString const& string, Renderer const&)
 {
     // Type0 fonts map bytes to character IDs ("CIDs"), and then CIDs to glyphs.
 
diff --git a/Userland/Libraries/LibPDF/Fonts/Type0Font.h b/Userland/Libraries/LibPDF/Fonts/Type0Font.h
index ebaf233fab3..812e582cf93 100644
--- a/Userland/Libraries/LibPDF/Fonts/Type0Font.h
+++ b/Userland/Libraries/LibPDF/Fonts/Type0Font.h
@@ -15,8 +15,8 @@ namespace PDF {
 class CIDFontType;
 
 struct CIDSystemInfo {
-    DeprecatedString registry;
-    DeprecatedString ordering;
+    ByteString registry;
+    ByteString ordering;
     u8 supplement;
 };
 
@@ -26,7 +26,7 @@ public:
     ~Type0Font();
 
     void set_font_size(float font_size) override;
-    PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, DeprecatedString const&, Renderer const&) override;
+    PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&, Renderer const&) override;
 
     DeprecatedFlyString base_font_name() const { return m_base_font_name; }
 
diff --git a/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.cpp b/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.cpp
index 8a94bf9290e..1907e3dbb93 100644
--- a/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.cpp
+++ b/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.cpp
@@ -387,7 +387,7 @@ PDFErrorOr<Type1FontProgram::Glyph> Type1FontProgram::parse_glyph(ReadonlyBytes
 
             case CallGsubr:
                 if (!is_type2)
-                    return error(DeprecatedString::formatted("CFF Gsubr only valid in type2 data"));
+                    return error(ByteString::formatted("CFF Gsubr only valid in type2 data"));
                 [[fallthrough]];
             case CallSubr: {
                 Vector<ByteBuffer> const& subroutines = v == CallSubr ? local_subroutines : global_subroutines;
@@ -725,7 +725,7 @@ PDFErrorOr<Type1FontProgram::Glyph> Type1FontProgram::parse_glyph(ReadonlyBytes
 }
 
 Error Type1FontProgram::error(
-    DeprecatedString const& message
+    ByteString const& message
 #ifdef PDF_DEBUG
     ,
     SourceLocation loc
diff --git a/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.h b/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.h
index 8462e6611d7..0f7be522140 100644
--- a/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.h
+++ b/Userland/Libraries/LibPDF/Fonts/Type1FontProgram.h
@@ -86,7 +86,7 @@ protected:
     static PDFErrorOr<Glyph> parse_glyph(ReadonlyBytes const&, Vector<ByteBuffer> const& local_subroutines, Vector<ByteBuffer> const& global_subroutines, GlyphParserState&, bool is_type2);
 
     static Error error(
-        DeprecatedString const& message
+        ByteString const& message
 #ifdef PDF_DEBUG
         ,
         SourceLocation loc = SourceLocation::current()
diff --git a/Userland/Libraries/LibPDF/Object.h b/Userland/Libraries/LibPDF/Object.h
index 0be2e9bee4c..6a2e98039f8 100644
--- a/Userland/Libraries/LibPDF/Object.h
+++ b/Userland/Libraries/LibPDF/Object.h
@@ -75,7 +75,7 @@ public:
     }
 
     virtual char const* type_name() const = 0;
-    virtual DeprecatedString to_deprecated_string(int indent) const = 0;
+    virtual ByteString to_byte_string(int indent) const = 0;
 
 protected:
 #define ENUMERATE_TYPE(_, name)    \
@@ -98,7 +98,7 @@ template<PDF::IsObject T>
 struct Formatter<T> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, T const& object)
     {
-        return Formatter<StringView>::format(builder, object.to_deprecated_string(0));
+        return Formatter<StringView>::format(builder, object.to_byte_string(0));
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/ObjectDerivatives.cpp b/Userland/Libraries/LibPDF/ObjectDerivatives.cpp
index 3b9f1b66e4e..62e513d27d3 100644
--- a/Userland/Libraries/LibPDF/ObjectDerivatives.cpp
+++ b/Userland/Libraries/LibPDF/ObjectDerivatives.cpp
@@ -53,18 +53,18 @@ static void append_indent(StringBuilder& builder, int indent)
         builder.append("  "sv);
 }
 
-DeprecatedString StringObject::to_deprecated_string(int) const
+ByteString StringObject::to_byte_string(int) const
 {
     if (is_binary())
-        return DeprecatedString::formatted("<{}>", encode_hex(string().bytes()).to_uppercase());
-    return DeprecatedString::formatted("({})", string());
+        return ByteString::formatted("<{}>", encode_hex(string().bytes()).to_uppercase());
+    return ByteString::formatted("({})", string());
 }
 
-DeprecatedString NameObject::to_deprecated_string(int) const
+ByteString NameObject::to_byte_string(int) const
 {
     StringBuilder builder;
     builder.appendff("/{}", this->name());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 Vector<float> ArrayObject::float_elements() const
@@ -77,7 +77,7 @@ Vector<float> ArrayObject::float_elements() const
     return values;
 }
 
-DeprecatedString ArrayObject::to_deprecated_string(int indent) const
+ByteString ArrayObject::to_byte_string(int indent) const
 {
     StringBuilder builder;
     builder.append("[\n"sv);
@@ -88,16 +88,16 @@ DeprecatedString ArrayObject::to_deprecated_string(int indent) const
             builder.append("\n"sv);
         first = false;
         append_indent(builder, indent + 1);
-        builder.appendff("{}", element.to_deprecated_string(indent));
+        builder.appendff("{}", element.to_byte_string(indent));
     }
 
     builder.append('\n');
     append_indent(builder, indent);
     builder.append(']');
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString DictObject::to_deprecated_string(int indent) const
+ByteString DictObject::to_byte_string(int indent) const
 {
     StringBuilder builder;
     append_indent(builder, indent);
@@ -110,19 +110,19 @@ DeprecatedString DictObject::to_deprecated_string(int indent) const
         first = false;
         append_indent(builder, indent + 1);
         builder.appendff("/{} ", key);
-        builder.appendff("{}", value.to_deprecated_string(indent + 1));
+        builder.appendff("{}", value.to_byte_string(indent + 1));
     }
 
     builder.append('\n');
     append_indent(builder, indent);
     builder.append(">>"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString StreamObject::to_deprecated_string(int indent) const
+ByteString StreamObject::to_byte_string(int indent) const
 {
     StringBuilder builder;
-    builder.appendff("{}\n", dict()->to_deprecated_string(indent));
+    builder.appendff("{}\n", dict()->to_byte_string(indent));
     builder.append("stream\n"sv);
 
     size_t ascii_count = 0;
@@ -156,19 +156,19 @@ DeprecatedString StreamObject::to_deprecated_string(int indent) const
     }
 
     builder.append("endstream"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString IndirectValue::to_deprecated_string(int indent) const
+ByteString IndirectValue::to_byte_string(int indent) const
 {
     StringBuilder builder;
     builder.appendff("{} {} obj\n", index(), generation_index());
     append_indent(builder, indent + 1);
-    builder.append(value().to_deprecated_string(indent + 1));
+    builder.append(value().to_byte_string(indent + 1));
     builder.append('\n');
     append_indent(builder, indent);
     builder.append("endobj"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/Userland/Libraries/LibPDF/ObjectDerivatives.h b/Userland/Libraries/LibPDF/ObjectDerivatives.h
index ef2f78f7ebd..e407a331e31 100644
--- a/Userland/Libraries/LibPDF/ObjectDerivatives.h
+++ b/Userland/Libraries/LibPDF/ObjectDerivatives.h
@@ -19,7 +19,7 @@ namespace PDF {
 
 class StringObject final : public Object {
 public:
-    StringObject(DeprecatedString string, bool is_binary)
+    StringObject(ByteString string, bool is_binary)
         : m_string(move(string))
         , m_is_binary(is_binary)
     {
@@ -27,18 +27,18 @@ public:
 
     ~StringObject() override = default;
 
-    [[nodiscard]] ALWAYS_INLINE DeprecatedString const& string() const { return m_string; }
+    [[nodiscard]] ALWAYS_INLINE ByteString const& string() const { return m_string; }
     [[nodiscard]] ALWAYS_INLINE bool is_binary() const { return m_is_binary; }
-    void set_string(DeprecatedString string) { m_string = move(string); }
+    void set_string(ByteString string) { m_string = move(string); }
 
     char const* type_name() const override { return "string"; }
-    DeprecatedString to_deprecated_string(int indent) const override;
+    ByteString to_byte_string(int indent) const override;
 
 protected:
     bool is_string() const override { return true; }
 
 private:
-    DeprecatedString m_string;
+    ByteString m_string;
     bool m_is_binary;
 };
 
@@ -54,7 +54,7 @@ public:
     [[nodiscard]] ALWAYS_INLINE DeprecatedFlyString const& name() const { return m_name; }
 
     char const* type_name() const override { return "name"; }
-    DeprecatedString to_deprecated_string(int indent) const override;
+    ByteString to_byte_string(int indent) const override;
 
 protected:
     bool is_name() const override { return true; }
@@ -95,7 +95,7 @@ public:
     {
         return "array";
     }
-    DeprecatedString to_deprecated_string(int indent) const override;
+    ByteString to_byte_string(int indent) const override;
 
 protected:
     bool is_array() const override { return true; }
@@ -142,7 +142,7 @@ public:
     {
         return "dict";
     }
-    DeprecatedString to_deprecated_string(int indent) const override;
+    ByteString to_byte_string(int indent) const override;
 
 protected:
     bool is_dict() const override { return true; }
@@ -166,7 +166,7 @@ public:
     [[nodiscard]] ByteBuffer& buffer() { return m_buffer; }
 
     char const* type_name() const override { return "stream"; }
-    DeprecatedString to_deprecated_string(int indent) const override;
+    ByteString to_byte_string(int indent) const override;
 
 private:
     bool is_stream() const override { return true; }
@@ -190,7 +190,7 @@ public:
     [[nodiscard]] ALWAYS_INLINE Value const& value() const { return m_value; }
 
     char const* type_name() const override { return "indirect_object"; }
-    DeprecatedString to_deprecated_string(int indent) const override;
+    ByteString to_byte_string(int indent) const override;
 
 protected:
     bool is_indirect_value() const override { return true; }
diff --git a/Userland/Libraries/LibPDF/Operator.h b/Userland/Libraries/LibPDF/Operator.h
index 0a05c7f4478..d043a146a75 100644
--- a/Userland/Libraries/LibPDF/Operator.h
+++ b/Userland/Libraries/LibPDF/Operator.h
@@ -179,7 +179,7 @@ struct Formatter<PDF::Operator> : Formatter<StringView> {
             builder.append(" ]"sv);
         }
 
-        return Formatter<StringView>::format(format_builder, builder.to_deprecated_string());
+        return Formatter<StringView>::format(format_builder, builder.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/Page.h b/Userland/Libraries/LibPDF/Page.h
index eb8d59a5cde..5fefa058e17 100644
--- a/Userland/Libraries/LibPDF/Page.h
+++ b/Userland/Libraries/LibPDF/Page.h
@@ -55,8 +55,8 @@ struct Formatter<PDF::Page> : Formatter<FormatString> {
     {
         return Formatter<FormatString>::format(builder,
             "Page {{\n  resources={}\n  contents={}\n  media_box={}\n  crop_box={}\n  user_unit={}\n  rotate={}\n}}"sv,
-            page.resources->to_deprecated_string(1),
-            page.contents->to_deprecated_string(1),
+            page.resources->to_byte_string(1),
+            page.contents->to_byte_string(1),
             page.media_box,
             page.crop_box,
             page.user_unit,
diff --git a/Userland/Libraries/LibPDF/Parser.cpp b/Userland/Libraries/LibPDF/Parser.cpp
index a80ef1c17c4..16b678ec53c 100644
--- a/Userland/Libraries/LibPDF/Parser.cpp
+++ b/Userland/Libraries/LibPDF/Parser.cpp
@@ -36,7 +36,7 @@ void Parser::set_document(WeakPtr<Document> const& document)
     m_document = document;
 }
 
-DeprecatedString Parser::parse_comment()
+ByteString Parser::parse_comment()
 {
     StringBuilder comment;
     while (true) {
@@ -52,7 +52,7 @@ DeprecatedString Parser::parse_comment()
         m_reader.consume_eol();
         m_reader.consume_whitespace();
     }
-    return comment.to_deprecated_string();
+    return comment.to_byte_string();
 }
 
 PDFErrorOr<Value> Parser::parse_value(CanBeIndirectValue can_be_indirect_value)
@@ -198,7 +198,7 @@ PDFErrorOr<Value> Parser::parse_number()
 
     m_reader.consume_whitespace();
 
-    auto string = DeprecatedString(m_reader.bytes().slice(start_offset, m_reader.offset() - start_offset));
+    auto string = ByteString(m_reader.bytes().slice(start_offset, m_reader.offset() - start_offset));
     if (is_float)
         return Value(strtof(string.characters(), nullptr));
 
@@ -238,14 +238,14 @@ PDFErrorOr<NonnullRefPtr<NameObject>> Parser::parse_name()
 
     m_reader.consume_whitespace();
 
-    return make_object<NameObject>(builder.to_deprecated_string());
+    return make_object<NameObject>(builder.to_byte_string());
 }
 
 PDFErrorOr<NonnullRefPtr<StringObject>> Parser::parse_string()
 {
     ScopeGuard guard([&] { m_reader.consume_whitespace(); });
 
-    DeprecatedString string;
+    ByteString string;
     bool is_binary_string;
 
     if (m_reader.matches('(')) {
@@ -264,7 +264,7 @@ PDFErrorOr<NonnullRefPtr<StringObject>> Parser::parse_string()
     return string_object;
 }
 
-PDFErrorOr<DeprecatedString> Parser::parse_literal_string()
+PDFErrorOr<ByteString> Parser::parse_literal_string()
 {
     VERIFY(m_reader.consume('('));
     StringBuilder builder;
@@ -342,10 +342,10 @@ PDFErrorOr<DeprecatedString> Parser::parse_literal_string()
         }
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-PDFErrorOr<DeprecatedString> Parser::parse_hex_string()
+PDFErrorOr<ByteString> Parser::parse_hex_string()
 {
     VERIFY(m_reader.consume('<'));
 
@@ -354,7 +354,7 @@ PDFErrorOr<DeprecatedString> Parser::parse_hex_string()
     while (true) {
         if (m_reader.matches('>')) {
             m_reader.consume();
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         } else {
             int hex_value = 0;
 
@@ -367,7 +367,7 @@ PDFErrorOr<DeprecatedString> Parser::parse_hex_string()
                     m_reader.consume();
                     hex_value *= 16;
                     builder.append(static_cast<char>(hex_value));
-                    return builder.to_deprecated_string();
+                    return builder.to_byte_string();
                 }
 
                 if (!isxdigit(ch))
@@ -602,7 +602,7 @@ PDFErrorOr<Vector<Operator>> Parser::parse_operators()
 }
 
 Error Parser::error(
-    DeprecatedString const& message
+    ByteString const& message
 #ifdef PDF_DEBUG
     ,
     SourceLocation loc
diff --git a/Userland/Libraries/LibPDF/Parser.h b/Userland/Libraries/LibPDF/Parser.h
index c79de2924d0..1e24d913aae 100644
--- a/Userland/Libraries/LibPDF/Parser.h
+++ b/Userland/Libraries/LibPDF/Parser.h
@@ -33,7 +33,7 @@ public:
 
     void set_document(WeakPtr<Document> const&);
 
-    DeprecatedString parse_comment();
+    ByteString parse_comment();
 
     void move_by(size_t count) { m_reader.move_by(count); }
     void move_to(size_t offset) { m_reader.move_to(offset); }
@@ -50,8 +50,8 @@ public:
     PDFErrorOr<Value> parse_number();
     PDFErrorOr<NonnullRefPtr<NameObject>> parse_name();
     PDFErrorOr<NonnullRefPtr<StringObject>> parse_string();
-    PDFErrorOr<DeprecatedString> parse_literal_string();
-    PDFErrorOr<DeprecatedString> parse_hex_string();
+    PDFErrorOr<ByteString> parse_literal_string();
+    PDFErrorOr<ByteString> parse_hex_string();
     PDFErrorOr<NonnullRefPtr<ArrayObject>> parse_array();
     PDFErrorOr<HashMap<DeprecatedFlyString, Value>> parse_dict_contents_until(char const*);
     PDFErrorOr<NonnullRefPtr<DictObject>> parse_dict();
@@ -73,7 +73,7 @@ public:
 
 protected:
     Error error(
-        DeprecatedString const& message
+        ByteString const& message
 #ifdef PDF_DEBUG
         ,
         SourceLocation loc = SourceLocation::current()
diff --git a/Userland/Libraries/LibPDF/Reader.h b/Userland/Libraries/LibPDF/Reader.h
index 3df2d0e5d78..17b9c9543ff 100644
--- a/Userland/Libraries/LibPDF/Reader.h
+++ b/Userland/Libraries/LibPDF/Reader.h
@@ -6,8 +6,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Function.h>
 #include <AK/ScopeGuard.h>
 #include <AK/Span.h>
@@ -64,7 +64,7 @@ public:
     PDFErrorOr<T> try_read()
     {
         if (sizeof(T) + m_offset > m_bytes.size()) {
-            auto message = DeprecatedString::formatted("Cannot read {} bytes at offset {} of ReadonlyBytes of size {}", sizeof(T), m_offset, m_bytes.size());
+            auto message = ByteString::formatted("Cannot read {} bytes at offset {} of ReadonlyBytes of size {}", sizeof(T), m_offset, m_bytes.size());
             return Error { Error::Type::Parse, message };
         }
         return read<T>();
@@ -92,7 +92,7 @@ public:
 
     bool matches(char const* chars) const
     {
-        DeprecatedString string(chars);
+        ByteString string(chars);
         if (remaining() < string.length())
             return false;
 
@@ -163,7 +163,7 @@ public:
 
         for (auto i = from; i <= to; i++) {
             char value = static_cast<char>(bytes().at(i));
-            auto line = DeprecatedString::formatted("  {}: '{}' (value={:3d}) ", i, value, static_cast<u8>(value));
+            auto line = ByteString::formatted("  {}: '{}' (value={:3d}) ", i, value, static_cast<u8>(value));
             if (i == offset()) {
                 dbgln("{} <<< current location, forwards={}", line, m_forwards);
             } else {
diff --git a/Userland/Libraries/LibPDF/Renderer.cpp b/Userland/Libraries/LibPDF/Renderer.cpp
index 862c6ef68fd..e2476997e17 100644
--- a/Userland/Libraries/LibPDF/Renderer.cpp
+++ b/Userland/Libraries/LibPDF/Renderer.cpp
@@ -829,7 +829,7 @@ PDFErrorOr<void> Renderer::set_graphics_state_from_dict(NonnullRefPtr<DictObject
     return {};
 }
 
-PDFErrorOr<void> Renderer::show_text(DeprecatedString const& string)
+PDFErrorOr<void> Renderer::show_text(ByteString const& string)
 {
     if (!text_state().font)
         return Error::rendering_unsupported_error("Can't draw text because an invalid font was in use");
diff --git a/Userland/Libraries/LibPDF/Renderer.h b/Userland/Libraries/LibPDF/Renderer.h
index ae5e1023c1e..dd0856d8d23 100644
--- a/Userland/Libraries/LibPDF/Renderer.h
+++ b/Userland/Libraries/LibPDF/Renderer.h
@@ -76,7 +76,7 @@ struct GraphicsState {
     RefPtr<ColorSpace> paint_color_space { DeviceGrayColorSpace::the() };
     ColorOrStyle stroke_style { Color::Black };
     ColorOrStyle paint_style { Color::Black };
-    DeprecatedString color_rendering_intent { "RelativeColorimetric"sv };
+    ByteString color_rendering_intent { "RelativeColorimetric"sv };
     float flatness_tolerance { 0.0f };
     float line_width { 1.0f };
     LineCapStyle line_cap_style { LineCapStyle::ButtCap };
@@ -132,7 +132,7 @@ private:
     void begin_path_paint();
     void end_path_paint();
     PDFErrorOr<void> set_graphics_state_from_dict(NonnullRefPtr<DictObject>);
-    PDFErrorOr<void> show_text(DeprecatedString const&);
+    PDFErrorOr<void> show_text(ByteString const&);
     PDFErrorOr<NonnullRefPtr<Gfx::Bitmap>> load_image(NonnullRefPtr<StreamObject>);
     PDFErrorOr<void> show_image(NonnullRefPtr<StreamObject>);
     void show_empty_image(int width, int height);
@@ -235,7 +235,7 @@ struct Formatter<PDF::LineDashPattern> : Formatter<StringView> {
         }
 
         builder.appendff("] {}", pattern.phase);
-        return format_builder.put_string(builder.to_deprecated_string());
+        return format_builder.put_string(builder.to_byte_string());
     }
 };
 
@@ -279,7 +279,7 @@ struct Formatter<PDF::TextState> : Formatter<StringView> {
         builder.appendff("    rise={}\n", state.rise);
         builder.appendff("    knockout={}\n", state.knockout);
         builder.append(" }"sv);
-        return format_builder.put_string(builder.to_deprecated_string());
+        return format_builder.put_string(builder.to_byte_string());
     }
 };
 
@@ -309,7 +309,7 @@ struct Formatter<PDF::GraphicsState> : Formatter<StringView> {
         builder.appendff("  line_dash_pattern={}\n", state.line_dash_pattern);
         builder.appendff("  text_state={}\n", state.text_state);
         builder.append('}');
-        return format_builder.put_string(builder.to_deprecated_string());
+        return format_builder.put_string(builder.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/Value.cpp b/Userland/Libraries/LibPDF/Value.cpp
index 1f652fdfee0..e0435413030 100644
--- a/Userland/Libraries/LibPDF/Value.cpp
+++ b/Userland/Libraries/LibPDF/Value.cpp
@@ -9,30 +9,30 @@
 
 namespace PDF {
 
-DeprecatedString Value::to_deprecated_string(int indent) const
+ByteString Value::to_byte_string(int indent) const
 {
     return visit(
-        [&](Empty const&) -> DeprecatedString {
+        [&](Empty const&) -> ByteString {
             // Return type deduction means that we can't use implicit conversions.
             return "<empty>";
         },
-        [&](nullptr_t const&) -> DeprecatedString {
+        [&](nullptr_t const&) -> ByteString {
             return "null";
         },
-        [&](bool const& b) -> DeprecatedString {
+        [&](bool const& b) -> ByteString {
             return b ? "true" : "false";
         },
         [&](int const& i) {
-            return DeprecatedString::number(i);
+            return ByteString::number(i);
         },
         [&](float const& f) {
-            return DeprecatedString::number(f);
+            return ByteString::number(f);
         },
         [&](Reference const& ref) {
-            return DeprecatedString::formatted("{} {} R", ref.as_ref_index(), ref.as_ref_generation_index());
+            return ByteString::formatted("{} {} R", ref.as_ref_index(), ref.as_ref_generation_index());
         },
         [&](NonnullRefPtr<Object> const& object) {
-            return object->to_deprecated_string(indent);
+            return object->to_byte_string(indent);
         });
 }
 
diff --git a/Userland/Libraries/LibPDF/Value.h b/Userland/Libraries/LibPDF/Value.h
index 68080329690..cb6911b9d47 100644
--- a/Userland/Libraries/LibPDF/Value.h
+++ b/Userland/Libraries/LibPDF/Value.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/RefPtr.h>
 #include <AK/Variant.h>
@@ -36,7 +36,7 @@ public:
         set<NonnullRefPtr<Object>>(*refptr);
     }
 
-    [[nodiscard]] DeprecatedString to_deprecated_string(int indent = 0) const;
+    [[nodiscard]] ByteString to_byte_string(int indent = 0) const;
 
     [[nodiscard]] ALWAYS_INLINE bool has_number() const { return has<int>() || has<float>(); }
 
@@ -95,7 +95,7 @@ template<>
 struct Formatter<PDF::Value> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, PDF::Value const& value)
     {
-        return Formatter<StringView>::format(builder, value.to_deprecated_string());
+        return Formatter<StringView>::format(builder, value.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibPDF/XRefTable.h b/Userland/Libraries/LibPDF/XRefTable.h
index 387949c833b..e7431f3bfa2 100644
--- a/Userland/Libraries/LibPDF/XRefTable.h
+++ b/Userland/Libraries/LibPDF/XRefTable.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/RefCounted.h>
 #include <AK/Vector.h>
@@ -126,7 +126,7 @@ struct Formatter<PDF::XRefEntry> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, PDF::XRefEntry const& entry)
     {
         return Formatter<StringView>::format(builder,
-            DeprecatedString::formatted("XRefEntry {{ offset={} generation={} used={} }}",
+            ByteString::formatted("XRefEntry {{ offset={} generation={} used={} }}",
                 entry.byte_offset,
                 entry.generation_number,
                 entry.in_use));
@@ -142,7 +142,7 @@ struct Formatter<PDF::XRefTable> : Formatter<StringView> {
         for (auto& entry : table.m_entries)
             builder.appendff("\n  {}", entry);
         builder.append("\n}"sv);
-        return Formatter<StringView>::format(format_builder, builder.to_deprecated_string());
+        return Formatter<StringView>::format(format_builder, builder.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibProtocol/Request.cpp b/Userland/Libraries/LibProtocol/Request.cpp
index 5260ba8f54e..325c8b9dc4f 100644
--- a/Userland/Libraries/LibProtocol/Request.cpp
+++ b/Userland/Libraries/LibProtocol/Request.cpp
@@ -116,7 +116,7 @@ void Request::did_progress(Badge<RequestClient>, Optional<u64> total_size, u64 d
         on_progress(total_size, downloaded_size);
 }
 
-void Request::did_receive_headers(Badge<RequestClient>, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code)
+void Request::did_receive_headers(Badge<RequestClient>, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code)
 {
     if (on_headers_received)
         on_headers_received(response_headers, response_code);
diff --git a/Userland/Libraries/LibProtocol/Request.h b/Userland/Libraries/LibProtocol/Request.h
index 83e59d157db..9a92f09b16f 100644
--- a/Userland/Libraries/LibProtocol/Request.h
+++ b/Userland/Libraries/LibProtocol/Request.h
@@ -8,7 +8,7 @@
 
 #include <AK/Badge.h>
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/MemoryStream.h>
 #include <AK/RefCounted.h>
@@ -23,8 +23,8 @@ class RequestClient;
 class Request : public RefCounted<Request> {
 public:
     struct CertificateAndKey {
-        DeprecatedString certificate;
-        DeprecatedString key;
+        ByteString certificate;
+        ByteString key;
     };
 
     static NonnullRefPtr<Request> create_from_id(Badge<RequestClient>, RequestClient& client, i32 request_id)
@@ -43,15 +43,15 @@ public:
     void set_should_buffer_all_input(bool);
 
     /// Note: Must be set before `set_should_buffer_all_input(true)`.
-    Function<void(bool success, u64 total_size, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code, ReadonlyBytes payload)> on_buffered_request_finish;
+    Function<void(bool success, u64 total_size, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code, ReadonlyBytes payload)> on_buffered_request_finish;
     Function<void(bool success, u64 total_size)> on_finish;
     Function<void(Optional<u64> total_size, u64 downloaded_size)> on_progress;
-    Function<void(HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code)> on_headers_received;
+    Function<void(HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code)> on_headers_received;
     Function<CertificateAndKey()> on_certificate_requested;
 
     void did_finish(Badge<RequestClient>, bool success, u64 total_size);
     void did_progress(Badge<RequestClient>, Optional<u64> total_size, u64 downloaded_size);
-    void did_receive_headers(Badge<RequestClient>, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code);
+    void did_receive_headers(Badge<RequestClient>, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code);
     void did_request_certificates(Badge<RequestClient>);
 
     RefPtr<Core::Notifier>& write_notifier(Badge<RequestClient>) { return m_write_notifier; }
@@ -68,7 +68,7 @@ private:
 
     struct InternalBufferedData {
         AllocatingMemoryStream payload_stream;
-        HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> response_headers;
+        HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> response_headers;
         Optional<u32> response_code;
     };
 
diff --git a/Userland/Libraries/LibProtocol/RequestClient.cpp b/Userland/Libraries/LibProtocol/RequestClient.cpp
index c4ba73f1a2e..de1d603c7e1 100644
--- a/Userland/Libraries/LibProtocol/RequestClient.cpp
+++ b/Userland/Libraries/LibProtocol/RequestClient.cpp
@@ -20,9 +20,9 @@ void RequestClient::ensure_connection(URL const& url, ::RequestServer::CacheLeve
 }
 
 template<typename RequestHashMapTraits>
-RefPtr<Request> RequestClient::start_request(DeprecatedString const& method, URL const& url, HashMap<DeprecatedString, DeprecatedString, RequestHashMapTraits> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const& proxy_data)
+RefPtr<Request> RequestClient::start_request(ByteString const& method, URL const& url, HashMap<ByteString, ByteString, RequestHashMapTraits> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const& proxy_data)
 {
-    auto headers_or_error = request_headers.template clone<Traits<DeprecatedString>>();
+    auto headers_or_error = request_headers.template clone<Traits<ByteString>>();
     if (headers_or_error.is_error())
         return nullptr;
     auto body_result = ByteBuffer::copy(request_body);
@@ -47,7 +47,7 @@ bool RequestClient::stop_request(Badge<Request>, Request& request)
     return IPCProxy::stop_request(request.id());
 }
 
-bool RequestClient::set_certificate(Badge<Request>, Request& request, DeprecatedString certificate, DeprecatedString key)
+bool RequestClient::set_certificate(Badge<Request>, Request& request, ByteString certificate, ByteString key)
 {
     if (!m_requests.contains(request.id()))
         return false;
@@ -70,7 +70,7 @@ void RequestClient::request_progress(i32 request_id, Optional<u64> const& total_
     }
 }
 
-void RequestClient::headers_became_available(i32 request_id, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> const& status_code)
+void RequestClient::headers_became_available(i32 request_id, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> const& status_code)
 {
     auto request = const_cast<Request*>(m_requests.get(request_id).value_or(nullptr));
     if (!request) {
@@ -95,5 +95,5 @@ void RequestClient::certificate_requested(i32 request_id)
 
 }
 
-template RefPtr<Protocol::Request> Protocol::RequestClient::start_request(DeprecatedString const& method, URL const&, HashMap<DeprecatedString, DeprecatedString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&);
-template RefPtr<Protocol::Request> Protocol::RequestClient::start_request(DeprecatedString const& method, URL const&, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&);
+template RefPtr<Protocol::Request> Protocol::RequestClient::start_request(ByteString const& method, URL const&, HashMap<ByteString, ByteString> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&);
+template RefPtr<Protocol::Request> Protocol::RequestClient::start_request(ByteString const& method, URL const&, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& request_headers, ReadonlyBytes request_body, Core::ProxyData const&);
diff --git a/Userland/Libraries/LibProtocol/RequestClient.h b/Userland/Libraries/LibProtocol/RequestClient.h
index 937601fa706..720d6abef29 100644
--- a/Userland/Libraries/LibProtocol/RequestClient.h
+++ b/Userland/Libraries/LibProtocol/RequestClient.h
@@ -23,19 +23,19 @@ class RequestClient final
 public:
     explicit RequestClient(NonnullOwnPtr<Core::LocalSocket>);
 
-    template<typename RequestHashMapTraits = Traits<DeprecatedString>>
-    RefPtr<Request> start_request(DeprecatedString const& method, URL const&, HashMap<DeprecatedString, DeprecatedString, RequestHashMapTraits> const& request_headers = {}, ReadonlyBytes request_body = {}, Core::ProxyData const& = {});
+    template<typename RequestHashMapTraits = Traits<ByteString>>
+    RefPtr<Request> start_request(ByteString const& method, URL const&, HashMap<ByteString, ByteString, RequestHashMapTraits> const& request_headers = {}, ReadonlyBytes request_body = {}, Core::ProxyData const& = {});
 
     void ensure_connection(URL const&, ::RequestServer::CacheLevel);
 
     bool stop_request(Badge<Request>, Request&);
-    bool set_certificate(Badge<Request>, Request&, DeprecatedString, DeprecatedString);
+    bool set_certificate(Badge<Request>, Request&, ByteString, ByteString);
 
 private:
     virtual void request_progress(i32, Optional<u64> const&, u64) override;
     virtual void request_finished(i32, bool, u64) override;
     virtual void certificate_requested(i32) override;
-    virtual void headers_became_available(i32, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const&, Optional<u32> const&) override;
+    virtual void headers_became_available(i32, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const&, Optional<u32> const&) override;
 
     HashMap<i32, RefPtr<Request>> m_requests;
 };
diff --git a/Userland/Libraries/LibProtocol/WebSocket.cpp b/Userland/Libraries/LibProtocol/WebSocket.cpp
index 7d5b3cbe659..9f6d51f8765 100644
--- a/Userland/Libraries/LibProtocol/WebSocket.cpp
+++ b/Userland/Libraries/LibProtocol/WebSocket.cpp
@@ -20,7 +20,7 @@ WebSocket::ReadyState WebSocket::ready_state()
     return (WebSocket::ReadyState)m_client->ready_state({}, *this);
 }
 
-DeprecatedString WebSocket::subprotocol_in_use()
+ByteString WebSocket::subprotocol_in_use()
 {
     return m_client->subprotocol_in_use({}, *this);
 }
@@ -35,7 +35,7 @@ void WebSocket::send(StringView text_message)
     send(ByteBuffer::copy(text_message.bytes()).release_value_but_fixme_should_propagate_errors(), true);
 }
 
-void WebSocket::close(u16 code, DeprecatedString reason)
+void WebSocket::close(u16 code, ByteString reason)
 {
     m_client->close({}, *this, code, move(reason));
 }
@@ -58,7 +58,7 @@ void WebSocket::did_error(Badge<WebSocketClient>, i32 error_code)
         on_error((WebSocket::Error)error_code);
 }
 
-void WebSocket::did_close(Badge<WebSocketClient>, u16 code, DeprecatedString reason, bool was_clean)
+void WebSocket::did_close(Badge<WebSocketClient>, u16 code, ByteString reason, bool was_clean)
 {
     if (on_close)
         on_close(code, move(reason), was_clean);
diff --git a/Userland/Libraries/LibProtocol/WebSocket.h b/Userland/Libraries/LibProtocol/WebSocket.h
index eb7d859cbaa..cc3f9e64ae9 100644
--- a/Userland/Libraries/LibProtocol/WebSocket.h
+++ b/Userland/Libraries/LibProtocol/WebSocket.h
@@ -8,7 +8,7 @@
 
 #include <AK/Badge.h>
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/RefCounted.h>
 #include <AK/WeakPtr.h>
@@ -22,8 +22,8 @@ class WebSocketClient;
 class WebSocket : public RefCounted<WebSocket> {
 public:
     struct CertificateAndKey {
-        DeprecatedString certificate;
-        DeprecatedString key;
+        ByteString certificate;
+        ByteString key;
     };
 
     struct Message {
@@ -53,22 +53,22 @@ public:
 
     ReadyState ready_state();
 
-    DeprecatedString subprotocol_in_use();
+    ByteString subprotocol_in_use();
 
     void send(ByteBuffer binary_or_text_message, bool is_text);
     void send(StringView text_message);
-    void close(u16 code = 1005, DeprecatedString reason = {});
+    void close(u16 code = 1005, ByteString reason = {});
 
     Function<void()> on_open;
     Function<void(Message)> on_message;
     Function<void(Error)> on_error;
-    Function<void(u16 code, DeprecatedString reason, bool was_clean)> on_close;
+    Function<void(u16 code, ByteString reason, bool was_clean)> on_close;
     Function<CertificateAndKey()> on_certificate_requested;
 
     void did_open(Badge<WebSocketClient>);
     void did_receive(Badge<WebSocketClient>, ByteBuffer, bool);
     void did_error(Badge<WebSocketClient>, i32);
-    void did_close(Badge<WebSocketClient>, u16, DeprecatedString, bool);
+    void did_close(Badge<WebSocketClient>, u16, ByteString, bool);
     void did_request_certificates(Badge<WebSocketClient>);
 
 private:
diff --git a/Userland/Libraries/LibProtocol/WebSocketClient.cpp b/Userland/Libraries/LibProtocol/WebSocketClient.cpp
index 652bec081fd..0f5d52ea441 100644
--- a/Userland/Libraries/LibProtocol/WebSocketClient.cpp
+++ b/Userland/Libraries/LibProtocol/WebSocketClient.cpp
@@ -14,7 +14,7 @@ WebSocketClient::WebSocketClient(NonnullOwnPtr<Core::LocalSocket> socket)
 {
 }
 
-RefPtr<WebSocket> WebSocketClient::connect(const URL& url, DeprecatedString const& origin, Vector<DeprecatedString> const& protocols, Vector<DeprecatedString> const& extensions, HashMap<DeprecatedString, DeprecatedString> const& request_headers)
+RefPtr<WebSocket> WebSocketClient::connect(const URL& url, ByteString const& origin, Vector<ByteString> const& protocols, Vector<ByteString> const& extensions, HashMap<ByteString, ByteString> const& request_headers)
 {
     auto headers_or_error = request_headers.clone();
     if (headers_or_error.is_error())
@@ -34,10 +34,10 @@ u32 WebSocketClient::ready_state(Badge<WebSocket>, WebSocket& connection)
     return IPCProxy::ready_state(connection.id());
 }
 
-DeprecatedString WebSocketClient::subprotocol_in_use(Badge<WebSocket>, WebSocket& connection)
+ByteString WebSocketClient::subprotocol_in_use(Badge<WebSocket>, WebSocket& connection)
 {
     if (!m_connections.contains(connection.id()))
-        return DeprecatedString::empty();
+        return ByteString::empty();
     return IPCProxy::subprotocol_in_use(connection.id());
 }
 
@@ -48,14 +48,14 @@ void WebSocketClient::send(Badge<WebSocket>, WebSocket& connection, ByteBuffer d
     async_send(connection.id(), is_text, move(data));
 }
 
-void WebSocketClient::close(Badge<WebSocket>, WebSocket& connection, u16 code, DeprecatedString message)
+void WebSocketClient::close(Badge<WebSocket>, WebSocket& connection, u16 code, ByteString message)
 {
     if (!m_connections.contains(connection.id()))
         return;
     async_close(connection.id(), code, move(message));
 }
 
-bool WebSocketClient::set_certificate(Badge<WebSocket>, WebSocket& connection, DeprecatedString certificate, DeprecatedString key)
+bool WebSocketClient::set_certificate(Badge<WebSocket>, WebSocket& connection, ByteString certificate, ByteString key)
 {
     if (!m_connections.contains(connection.id()))
         return false;
@@ -83,7 +83,7 @@ void WebSocketClient::errored(i32 connection_id, i32 message)
         maybe_connection.value()->did_error({}, message);
 }
 
-void WebSocketClient::closed(i32 connection_id, u16 code, DeprecatedString const& reason, bool clean)
+void WebSocketClient::closed(i32 connection_id, u16 code, ByteString const& reason, bool clean)
 {
     auto maybe_connection = m_connections.get(connection_id);
     if (maybe_connection.has_value())
diff --git a/Userland/Libraries/LibProtocol/WebSocketClient.h b/Userland/Libraries/LibProtocol/WebSocketClient.h
index 4eb94dcde38..aab80123e5f 100644
--- a/Userland/Libraries/LibProtocol/WebSocketClient.h
+++ b/Userland/Libraries/LibProtocol/WebSocketClient.h
@@ -23,19 +23,19 @@ class WebSocketClient final
 public:
     explicit WebSocketClient(NonnullOwnPtr<Core::LocalSocket>);
 
-    RefPtr<WebSocket> connect(const URL&, DeprecatedString const& origin = {}, Vector<DeprecatedString> const& protocols = {}, Vector<DeprecatedString> const& extensions = {}, HashMap<DeprecatedString, DeprecatedString> const& request_headers = {});
+    RefPtr<WebSocket> connect(const URL&, ByteString const& origin = {}, Vector<ByteString> const& protocols = {}, Vector<ByteString> const& extensions = {}, HashMap<ByteString, ByteString> const& request_headers = {});
 
     u32 ready_state(Badge<WebSocket>, WebSocket&);
-    DeprecatedString subprotocol_in_use(Badge<WebSocket>, WebSocket&);
+    ByteString subprotocol_in_use(Badge<WebSocket>, WebSocket&);
     void send(Badge<WebSocket>, WebSocket&, ByteBuffer, bool is_text);
-    void close(Badge<WebSocket>, WebSocket&, u16 code, DeprecatedString reason);
-    bool set_certificate(Badge<WebSocket>, WebSocket&, DeprecatedString, DeprecatedString);
+    void close(Badge<WebSocket>, WebSocket&, u16 code, ByteString reason);
+    bool set_certificate(Badge<WebSocket>, WebSocket&, ByteString, ByteString);
 
 private:
     virtual void connected(i32) override;
     virtual void received(i32, bool, ByteBuffer const&) override;
     virtual void errored(i32, i32) override;
-    virtual void closed(i32, u16, DeprecatedString const&, bool) override;
+    virtual void closed(i32, u16, ByteString const&, bool) override;
     virtual void certificate_requested(i32) override;
 
     HashMap<i32, NonnullRefPtr<WebSocket>> m_connections;
diff --git a/Userland/Libraries/LibRegex/C/Regex.cpp b/Userland/Libraries/LibRegex/C/Regex.cpp
index 1281d04816a..0b8a988ca5e 100644
--- a/Userland/Libraries/LibRegex/C/Regex.cpp
+++ b/Userland/Libraries/LibRegex/C/Regex.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <AK/Variant.h>
 #include <LibRegex/Regex.h>
@@ -23,7 +23,7 @@ struct internal_regex_t {
     Optional<Variant<NonnullOwnPtr<Regex<PosixExtended>>, NonnullOwnPtr<Regex<PosixBasic>>>> re;
     size_t re_pat_errpos;
     ReError re_pat_err;
-    DeprecatedString re_pat;
+    ByteString re_pat;
 };
 
 static internal_regex_t* impl_from(regex_t* re)
@@ -55,7 +55,7 @@ int regcomp(regex_t* reg, char const* pattern, int cflags)
 
     preg->cflags = cflags;
 
-    DeprecatedString pattern_str(pattern);
+    ByteString pattern_str(pattern);
     if (is_extended)
         preg->re = make<Regex<PosixExtended>>(pattern_str, PosixOptions {} | (PosixFlags)cflags | PosixFlags::SkipTrimEmptyMatches);
     else
@@ -193,7 +193,7 @@ static StringView get_error(ReError errcode)
 
 size_t regerror(int errcode, regex_t const* reg, char* errbuf, size_t errbuf_size)
 {
-    DeprecatedString error;
+    ByteString error;
     auto const* preg = impl_from(reg);
 
     if (!preg)
diff --git a/Userland/Libraries/LibRegex/RegexByteCode.cpp b/Userland/Libraries/LibRegex/RegexByteCode.cpp
index c5ecf5d7267..77467d7b934 100644
--- a/Userland/Libraries/LibRegex/RegexByteCode.cpp
+++ b/Userland/Libraries/LibRegex/RegexByteCode.cpp
@@ -381,7 +381,7 @@ ALWAYS_INLINE ExecutionResult OpCode_SaveRightCaptureGroup::execute(MatchInput c
     auto view = input.view.substring_view(start_position, length);
 
     if (input.regex_options & AllFlags::StringCopyMatches) {
-        match = { view.to_deprecated_string(), input.line, start_position, input.global_offset + start_position }; // create a copy of the original string
+        match = { view.to_byte_string(), input.line, start_position, input.global_offset + start_position }; // create a copy of the original string
     } else {
         match = { view, input.line, start_position, input.global_offset + start_position }; // take view to original string
     }
@@ -406,7 +406,7 @@ ALWAYS_INLINE ExecutionResult OpCode_SaveRightNamedCaptureGroup::execute(MatchIn
     auto view = input.view.substring_view(start_position, length);
 
     if (input.regex_options & AllFlags::StringCopyMatches) {
-        match = { view.to_deprecated_string(), name(), input.line, start_position, input.global_offset + start_position }; // create a copy of the original string
+        match = { view.to_byte_string(), name(), input.line, start_position, input.global_offset + start_position }; // create a copy of the original string
     } else {
         match = { view, name(), input.line, start_position, input.global_offset + start_position }; // take view to original string
     }
@@ -509,7 +509,7 @@ ALWAYS_INLINE ExecutionResult OpCode_Compare::execute(MatchInput const& input, M
             if (input.view.length() < state.string_position + length)
                 return ExecutionResult::Failed_ExecuteLowPrioForks;
 
-            Optional<DeprecatedString> str;
+            Optional<ByteString> str;
             Utf16Data utf16;
             Vector<u32> data;
             data.ensure_capacity(length);
@@ -893,9 +893,9 @@ ALWAYS_INLINE void OpCode_Compare::compare_script_extension(MatchInput const& in
     }
 }
 
-DeprecatedString OpCode_Compare::arguments_string() const
+ByteString OpCode_Compare::arguments_string() const
 {
-    return DeprecatedString::formatted("argc={}, args={} ", arguments_count(), arguments_size());
+    return ByteString::formatted("argc={}, args={} ", arguments_count(), arguments_size());
 }
 
 Vector<CompareTypeAndValuePair> OpCode_Compare::flat_compares() const
@@ -941,16 +941,16 @@ Vector<CompareTypeAndValuePair> OpCode_Compare::flat_compares() const
     return result;
 }
 
-Vector<DeprecatedString> OpCode_Compare::variable_arguments_to_deprecated_string(Optional<MatchInput const&> input) const
+Vector<ByteString> OpCode_Compare::variable_arguments_to_byte_string(Optional<MatchInput const&> input) const
 {
-    Vector<DeprecatedString> result;
+    Vector<ByteString> result;
 
     size_t offset { state().instruction_position + 3 };
     RegexStringView const& view = ((input.has_value()) ? input.value().view : StringView {});
 
     for (size_t i = 0; i < arguments_count(); ++i) {
         auto compare_type = (CharacterCompareType)m_bytecode->at(offset++);
-        result.empend(DeprecatedString::formatted("type={} [{}]", (size_t)compare_type, character_compare_type_name(compare_type)));
+        result.empend(ByteString::formatted("type={} [{}]", (size_t)compare_type, character_compare_type_name(compare_type)));
 
         auto string_start_offset = state().string_position_before_match;
 
@@ -958,39 +958,39 @@ Vector<DeprecatedString> OpCode_Compare::variable_arguments_to_deprecated_string
             auto ch = m_bytecode->at(offset++);
             auto is_ascii = is_ascii_printable(ch);
             if (is_ascii)
-                result.empend(DeprecatedString::formatted(" value='{:c}'", static_cast<char>(ch)));
+                result.empend(ByteString::formatted(" value='{:c}'", static_cast<char>(ch)));
             else
-                result.empend(DeprecatedString::formatted(" value={:x}", ch));
+                result.empend(ByteString::formatted(" value={:x}", ch));
 
             if (!view.is_null() && view.length() > string_start_offset) {
                 if (is_ascii) {
-                    result.empend(DeprecatedString::formatted(
+                    result.empend(ByteString::formatted(
                         " compare against: '{}'",
-                        view.substring_view(string_start_offset, string_start_offset > view.length() ? 0 : 1).to_deprecated_string()));
+                        view.substring_view(string_start_offset, string_start_offset > view.length() ? 0 : 1).to_byte_string()));
                 } else {
-                    auto str = view.substring_view(string_start_offset, string_start_offset > view.length() ? 0 : 1).to_deprecated_string();
+                    auto str = view.substring_view(string_start_offset, string_start_offset > view.length() ? 0 : 1).to_byte_string();
                     u8 buf[8] { 0 };
                     __builtin_memcpy(buf, str.characters(), min(str.length(), sizeof(buf)));
-                    result.empend(DeprecatedString::formatted(" compare against: {:x},{:x},{:x},{:x},{:x},{:x},{:x},{:x}",
+                    result.empend(ByteString::formatted(" compare against: {:x},{:x},{:x},{:x},{:x},{:x},{:x},{:x}",
                         buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]));
                 }
             }
         } else if (compare_type == CharacterCompareType::Reference) {
             auto ref = m_bytecode->at(offset++);
-            result.empend(DeprecatedString::formatted(" number={}", ref));
+            result.empend(ByteString::formatted(" number={}", ref));
             if (input.has_value()) {
                 if (state().capture_group_matches.size() > input->match_index) {
                     auto& match = state().capture_group_matches[input->match_index];
                     if (match.size() > ref) {
                         auto& group = match[ref];
-                        result.empend(DeprecatedString::formatted(" left={}", group.left_column));
-                        result.empend(DeprecatedString::formatted(" right={}", group.left_column + group.view.length_in_code_units()));
-                        result.empend(DeprecatedString::formatted(" contents='{}'", group.view));
+                        result.empend(ByteString::formatted(" left={}", group.left_column));
+                        result.empend(ByteString::formatted(" right={}", group.left_column + group.view.length_in_code_units()));
+                        result.empend(ByteString::formatted(" contents='{}'", group.view));
                     } else {
-                        result.empend(DeprecatedString::formatted(" (invalid ref, max={})", match.size() - 1));
+                        result.empend(ByteString::formatted(" (invalid ref, max={})", match.size() - 1));
                     }
                 } else {
-                    result.empend(DeprecatedString::formatted(" (invalid index {}, max={})", input->match_index, state().capture_group_matches.size() - 1));
+                    result.empend(ByteString::formatted(" (invalid index {}, max={})", input->match_index, state().capture_group_matches.size() - 1));
                 }
             }
         } else if (compare_type == CharacterCompareType::String) {
@@ -998,42 +998,42 @@ Vector<DeprecatedString> OpCode_Compare::variable_arguments_to_deprecated_string
             StringBuilder str_builder;
             for (size_t i = 0; i < length; ++i)
                 str_builder.append(m_bytecode->at(offset++));
-            result.empend(DeprecatedString::formatted(" value=\"{}\"", str_builder.string_view().substring_view(0, length)));
+            result.empend(ByteString::formatted(" value=\"{}\"", str_builder.string_view().substring_view(0, length)));
             if (!view.is_null() && view.length() > state().string_position)
-                result.empend(DeprecatedString::formatted(
+                result.empend(ByteString::formatted(
                     " compare against: \"{}\"",
-                    input.value().view.substring_view(string_start_offset, string_start_offset + length > view.length() ? 0 : length).to_deprecated_string()));
+                    input.value().view.substring_view(string_start_offset, string_start_offset + length > view.length() ? 0 : length).to_byte_string()));
         } else if (compare_type == CharacterCompareType::CharClass) {
             auto character_class = (CharClass)m_bytecode->at(offset++);
-            result.empend(DeprecatedString::formatted(" ch_class={} [{}]", (size_t)character_class, character_class_name(character_class)));
+            result.empend(ByteString::formatted(" ch_class={} [{}]", (size_t)character_class, character_class_name(character_class)));
             if (!view.is_null() && view.length() > state().string_position)
-                result.empend(DeprecatedString::formatted(
+                result.empend(ByteString::formatted(
                     " compare against: '{}'",
-                    input.value().view.substring_view(string_start_offset, state().string_position > view.length() ? 0 : 1).to_deprecated_string()));
+                    input.value().view.substring_view(string_start_offset, state().string_position > view.length() ? 0 : 1).to_byte_string()));
         } else if (compare_type == CharacterCompareType::CharRange) {
             auto value = (CharRange)m_bytecode->at(offset++);
-            result.empend(DeprecatedString::formatted(" ch_range={:x}-{:x}", value.from, value.to));
+            result.empend(ByteString::formatted(" ch_range={:x}-{:x}", value.from, value.to));
             if (!view.is_null() && view.length() > state().string_position)
-                result.empend(DeprecatedString::formatted(
+                result.empend(ByteString::formatted(
                     " compare against: '{}'",
-                    input.value().view.substring_view(string_start_offset, state().string_position > view.length() ? 0 : 1).to_deprecated_string()));
+                    input.value().view.substring_view(string_start_offset, state().string_position > view.length() ? 0 : 1).to_byte_string()));
         } else if (compare_type == CharacterCompareType::LookupTable) {
             auto count = m_bytecode->at(offset++);
             for (size_t j = 0; j < count; ++j) {
                 auto range = (CharRange)m_bytecode->at(offset++);
-                result.append(DeprecatedString::formatted(" {:x}-{:x}", range.from, range.to));
+                result.append(ByteString::formatted(" {:x}-{:x}", range.from, range.to));
             }
             if (!view.is_null() && view.length() > state().string_position)
-                result.empend(DeprecatedString::formatted(
+                result.empend(ByteString::formatted(
                     " compare against: '{}'",
-                    input.value().view.substring_view(string_start_offset, state().string_position > view.length() ? 0 : 1).to_deprecated_string()));
+                    input.value().view.substring_view(string_start_offset, state().string_position > view.length() ? 0 : 1).to_byte_string()));
         } else if (compare_type == CharacterCompareType::GeneralCategory
             || compare_type == CharacterCompareType::Property
             || compare_type == CharacterCompareType::Script
             || compare_type == CharacterCompareType::ScriptExtension) {
 
             auto value = m_bytecode->at(offset++);
-            result.empend(DeprecatedString::formatted(" value={}", value));
+            result.empend(ByteString::formatted(" value={}", value));
         }
     }
     return result;
diff --git a/Userland/Libraries/LibRegex/RegexByteCode.h b/Userland/Libraries/LibRegex/RegexByteCode.h
index 6dc0b8845ac..631f6fafd1b 100644
--- a/Userland/Libraries/LibRegex/RegexByteCode.h
+++ b/Userland/Libraries/LibRegex/RegexByteCode.h
@@ -583,12 +583,12 @@ public:
         return *m_state;
     }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
-        return DeprecatedString::formatted("[{:#02X}] {}", (int)opcode_id(), name(opcode_id()));
+        return ByteString::formatted("[{:#02X}] {}", (int)opcode_id(), name(opcode_id()));
     }
 
-    virtual DeprecatedString arguments_string() const = 0;
+    virtual ByteString arguments_string() const = 0;
 
     ALWAYS_INLINE ByteCode const& bytecode() const { return *m_bytecode; }
 
@@ -602,7 +602,7 @@ public:
     ExecutionResult execute(MatchInput const& input, MatchState& state) const override;
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::Exit; }
     ALWAYS_INLINE size_t size() const override { return 1; }
-    DeprecatedString arguments_string() const override { return DeprecatedString::empty(); }
+    ByteString arguments_string() const override { return ByteString::empty(); }
 };
 
 class OpCode_FailForks final : public OpCode {
@@ -610,7 +610,7 @@ public:
     ExecutionResult execute(MatchInput const& input, MatchState& state) const override;
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::FailForks; }
     ALWAYS_INLINE size_t size() const override { return 1; }
-    DeprecatedString arguments_string() const override { return DeprecatedString::empty(); }
+    ByteString arguments_string() const override { return ByteString::empty(); }
 };
 
 class OpCode_Save final : public OpCode {
@@ -618,7 +618,7 @@ public:
     ExecutionResult execute(MatchInput const& input, MatchState& state) const override;
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::Save; }
     ALWAYS_INLINE size_t size() const override { return 1; }
-    DeprecatedString arguments_string() const override { return DeprecatedString::empty(); }
+    ByteString arguments_string() const override { return ByteString::empty(); }
 };
 
 class OpCode_Restore final : public OpCode {
@@ -626,7 +626,7 @@ public:
     ExecutionResult execute(MatchInput const& input, MatchState& state) const override;
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::Restore; }
     ALWAYS_INLINE size_t size() const override { return 1; }
-    DeprecatedString arguments_string() const override { return DeprecatedString::empty(); }
+    ByteString arguments_string() const override { return ByteString::empty(); }
 };
 
 class OpCode_GoBack final : public OpCode {
@@ -635,7 +635,7 @@ public:
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::GoBack; }
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE size_t count() const { return argument(0); }
-    DeprecatedString arguments_string() const override { return DeprecatedString::formatted("count={}", count()); }
+    ByteString arguments_string() const override { return ByteString::formatted("count={}", count()); }
 };
 
 class OpCode_Jump final : public OpCode {
@@ -644,9 +644,9 @@ public:
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::Jump; }
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE ssize_t offset() const { return argument(0); }
-    DeprecatedString arguments_string() const override
+    ByteString arguments_string() const override
     {
-        return DeprecatedString::formatted("offset={} [&{}]", offset(), state().instruction_position + size() + offset());
+        return ByteString::formatted("offset={} [&{}]", offset(), state().instruction_position + size() + offset());
     }
 };
 
@@ -656,9 +656,9 @@ public:
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::ForkJump; }
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE ssize_t offset() const { return argument(0); }
-    DeprecatedString arguments_string() const override
+    ByteString arguments_string() const override
     {
-        return DeprecatedString::formatted("offset={} [&{}], sp: {}", offset(), state().instruction_position + size() + offset(), state().string_position);
+        return ByteString::formatted("offset={} [&{}], sp: {}", offset(), state().instruction_position + size() + offset(), state().string_position);
     }
 };
 
@@ -674,9 +674,9 @@ public:
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::ForkStay; }
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE ssize_t offset() const { return argument(0); }
-    DeprecatedString arguments_string() const override
+    ByteString arguments_string() const override
     {
-        return DeprecatedString::formatted("offset={} [&{}], sp: {}", offset(), state().instruction_position + size() + offset(), state().string_position);
+        return ByteString::formatted("offset={} [&{}], sp: {}", offset(), state().instruction_position + size() + offset(), state().string_position);
     }
 };
 
@@ -691,7 +691,7 @@ public:
     ExecutionResult execute(MatchInput const& input, MatchState& state) const override;
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::CheckBegin; }
     ALWAYS_INLINE size_t size() const override { return 1; }
-    DeprecatedString arguments_string() const override { return DeprecatedString::empty(); }
+    ByteString arguments_string() const override { return ByteString::empty(); }
 };
 
 class OpCode_CheckEnd final : public OpCode {
@@ -699,7 +699,7 @@ public:
     ExecutionResult execute(MatchInput const& input, MatchState& state) const override;
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::CheckEnd; }
     ALWAYS_INLINE size_t size() const override { return 1; }
-    DeprecatedString arguments_string() const override { return DeprecatedString::empty(); }
+    ByteString arguments_string() const override { return ByteString::empty(); }
 };
 
 class OpCode_CheckBoundary final : public OpCode {
@@ -709,7 +709,7 @@ public:
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE size_t arguments_count() const { return 1; }
     ALWAYS_INLINE BoundaryCheckType type() const { return static_cast<BoundaryCheckType>(argument(0)); }
-    DeprecatedString arguments_string() const override { return DeprecatedString::formatted("kind={} ({})", (long unsigned int)argument(0), boundary_check_type_name(type())); }
+    ByteString arguments_string() const override { return ByteString::formatted("kind={} ({})", (long unsigned int)argument(0), boundary_check_type_name(type())); }
 };
 
 class OpCode_ClearCaptureGroup final : public OpCode {
@@ -718,7 +718,7 @@ public:
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::ClearCaptureGroup; }
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE size_t id() const { return argument(0); }
-    DeprecatedString arguments_string() const override { return DeprecatedString::formatted("id={}", id()); }
+    ByteString arguments_string() const override { return ByteString::formatted("id={}", id()); }
 };
 
 class OpCode_SaveLeftCaptureGroup final : public OpCode {
@@ -727,7 +727,7 @@ public:
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::SaveLeftCaptureGroup; }
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE size_t id() const { return argument(0); }
-    DeprecatedString arguments_string() const override { return DeprecatedString::formatted("id={}", id()); }
+    ByteString arguments_string() const override { return ByteString::formatted("id={}", id()); }
 };
 
 class OpCode_SaveRightCaptureGroup final : public OpCode {
@@ -736,7 +736,7 @@ public:
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::SaveRightCaptureGroup; }
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE size_t id() const { return argument(0); }
-    DeprecatedString arguments_string() const override { return DeprecatedString::formatted("id={}", id()); }
+    ByteString arguments_string() const override { return ByteString::formatted("id={}", id()); }
 };
 
 class OpCode_SaveRightNamedCaptureGroup final : public OpCode {
@@ -747,9 +747,9 @@ public:
     ALWAYS_INLINE StringView name() const { return { reinterpret_cast<char*>(argument(0)), length() }; }
     ALWAYS_INLINE size_t length() const { return argument(1); }
     ALWAYS_INLINE size_t id() const { return argument(2); }
-    DeprecatedString arguments_string() const override
+    ByteString arguments_string() const override
     {
-        return DeprecatedString::formatted("name={}, length={}", name(), length());
+        return ByteString::formatted("name={}, length={}", name(), length());
     }
 };
 
@@ -760,8 +760,8 @@ public:
     ALWAYS_INLINE size_t size() const override { return arguments_size() + 3; }
     ALWAYS_INLINE size_t arguments_count() const { return argument(0); }
     ALWAYS_INLINE size_t arguments_size() const { return argument(1); }
-    DeprecatedString arguments_string() const override;
-    Vector<DeprecatedString> variable_arguments_to_deprecated_string(Optional<MatchInput const&> input = {}) const;
+    ByteString arguments_string() const override;
+    Vector<ByteString> variable_arguments_to_byte_string(Optional<MatchInput const&> input = {}) const;
     Vector<CompareTypeAndValuePair> flat_compares() const;
     static bool matches_character_class(CharClass, u32, bool insensitive);
 
@@ -784,10 +784,10 @@ public:
     ALWAYS_INLINE size_t offset() const { return argument(0); }
     ALWAYS_INLINE u64 count() const { return argument(1); }
     ALWAYS_INLINE size_t id() const { return argument(2); }
-    DeprecatedString arguments_string() const override
+    ByteString arguments_string() const override
     {
         auto reps = id() < state().repetition_marks.size() ? state().repetition_marks.at(id()) : 0;
-        return DeprecatedString::formatted("offset={} count={} id={} rep={}, sp: {}", offset(), count() + 1, id(), reps + 1, state().string_position);
+        return ByteString::formatted("offset={} count={} id={} rep={}, sp: {}", offset(), count() + 1, id(), reps + 1, state().string_position);
     }
 };
 
@@ -797,10 +797,10 @@ public:
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::ResetRepeat; }
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE size_t id() const { return argument(0); }
-    DeprecatedString arguments_string() const override
+    ByteString arguments_string() const override
     {
         auto reps = id() < state().repetition_marks.size() ? state().repetition_marks.at(id()) : 0;
-        return DeprecatedString::formatted("id={} rep={}", id(), reps + 1);
+        return ByteString::formatted("id={} rep={}", id(), reps + 1);
     }
 };
 
@@ -810,7 +810,7 @@ public:
     ALWAYS_INLINE OpCodeId opcode_id() const override { return OpCodeId::Checkpoint; }
     ALWAYS_INLINE size_t size() const override { return 2; }
     ALWAYS_INLINE size_t id() const { return argument(0); }
-    DeprecatedString arguments_string() const override { return DeprecatedString::formatted("id={}", id()); }
+    ByteString arguments_string() const override { return ByteString::formatted("id={}", id()); }
 };
 
 class OpCode_JumpNonEmpty final : public OpCode {
@@ -821,9 +821,9 @@ public:
     ALWAYS_INLINE ssize_t offset() const { return argument(0); }
     ALWAYS_INLINE ssize_t checkpoint() const { return argument(1); }
     ALWAYS_INLINE OpCodeId form() const { return (OpCodeId)argument(2); }
-    DeprecatedString arguments_string() const override
+    ByteString arguments_string() const override
     {
-        return DeprecatedString::formatted("{} offset={} [&{}], cp={}",
+        return ByteString::formatted("{} offset={} [&{}], cp={}",
             opcode_id_name(form()),
             offset(), state().instruction_position + size() + offset(),
             checkpoint());
diff --git a/Userland/Libraries/LibRegex/RegexDebug.h b/Userland/Libraries/LibRegex/RegexDebug.h
index 8c1f9eb4a25..165c0ca3ec2 100644
--- a/Userland/Libraries/LibRegex/RegexDebug.h
+++ b/Userland/Libraries/LibRegex/RegexDebug.h
@@ -54,19 +54,19 @@ public:
         fflush(m_file);
     }
 
-    void print_opcode(DeprecatedString const& system, OpCode& opcode, MatchState& state, size_t recursion = 0, bool newline = true) const
+    void print_opcode(ByteString const& system, OpCode& opcode, MatchState& state, size_t recursion = 0, bool newline = true) const
     {
         out(m_file, "{:15} | {:5} | {:9} | {:35} | {:30} | {:20}",
             system.characters(),
             state.instruction_position,
             recursion,
-            opcode.to_deprecated_string().characters(),
+            opcode.to_byte_string().characters(),
             opcode.arguments_string().characters(),
-            DeprecatedString::formatted("ip: {:3},   sp: {:3}", state.instruction_position, state.string_position));
+            ByteString::formatted("ip: {:3},   sp: {:3}", state.instruction_position, state.string_position));
         if (newline)
             outln();
         if (newline && is<OpCode_Compare>(opcode)) {
-            for (auto& line : to<OpCode_Compare>(opcode).variable_arguments_to_deprecated_string())
+            for (auto& line : to<OpCode_Compare>(opcode).variable_arguments_to_byte_string())
                 outln(m_file, "{:15} | {:5} | {:9} | {:35} | {:30} | {:20}", "", "", "", "", line, "");
         }
     }
@@ -84,10 +84,10 @@ public:
             builder.appendff(", next ip: {}", state.instruction_position + opcode.size());
         }
 
-        outln(m_file, " | {:20}", builder.to_deprecated_string());
+        outln(m_file, " | {:20}", builder.to_byte_string());
 
         if (is<OpCode_Compare>(opcode)) {
-            for (auto& line : to<OpCode_Compare>(opcode).variable_arguments_to_deprecated_string(input)) {
+            for (auto& line : to<OpCode_Compare>(opcode).variable_arguments_to_byte_string(input)) {
                 outln(m_file, "{:15} | {:5} | {:9} | {:35} | {:30} | {:20}", "", "", "", "", line, "");
             }
         }
@@ -103,7 +103,7 @@ public:
         for (size_t i = 0; i < length; ++i) {
             builder.append('=');
         }
-        auto str = builder.to_deprecated_string();
+        auto str = builder.to_byte_string();
         VERIFY(!str.is_empty());
 
         outln(m_file, "{}", str);
@@ -114,11 +114,11 @@ public:
             builder.append('-');
         }
         builder.append('\n');
-        m_debug_stripline = builder.to_deprecated_string();
+        m_debug_stripline = builder.to_byte_string();
     }
 
 private:
-    DeprecatedString m_debug_stripline;
+    ByteString m_debug_stripline;
     FILE* m_file;
 };
 
diff --git a/Userland/Libraries/LibRegex/RegexMatch.h b/Userland/Libraries/LibRegex/RegexMatch.h
index a09eb25aaf3..3a13280b21e 100644
--- a/Userland/Libraries/LibRegex/RegexMatch.h
+++ b/Userland/Libraries/LibRegex/RegexMatch.h
@@ -10,8 +10,8 @@
 #include "RegexOptions.h"
 #include <AK/Error.h>
 
+#include <AK/ByteString.h>
 #include <AK/DeprecatedFlyString.h>
-#include <AK/DeprecatedString.h>
 #include <AK/HashMap.h>
 #include <AK/MemMem.h>
 #include <AK/RedBlackTree.h>
@@ -158,7 +158,7 @@ class RegexStringView {
 public:
     RegexStringView() = default;
 
-    RegexStringView(DeprecatedString const& string)
+    RegexStringView(ByteString const& string)
         : m_view(string.view())
     {
     }
@@ -188,7 +188,7 @@ public:
     {
     }
 
-    explicit RegexStringView(DeprecatedString&&) = delete;
+    explicit RegexStringView(ByteString&&) = delete;
 
     bool is_string_view() const
     {
@@ -277,14 +277,14 @@ public:
         return view;
     }
 
-    RegexStringView construct_as_same(Span<u32> data, Optional<DeprecatedString>& optional_string_storage, Utf16Data& optional_utf16_storage) const
+    RegexStringView construct_as_same(Span<u32> data, Optional<ByteString>& optional_string_storage, Utf16Data& optional_utf16_storage) const
     {
         auto view = m_view.visit(
             [&]<typename T>(T const&) {
                 StringBuilder builder;
                 for (auto ch : data)
                     builder.append(ch); // Note: The type conversion is intentional.
-                optional_string_storage = builder.to_deprecated_string();
+                optional_string_storage = builder.to_byte_string();
                 return RegexStringView { T { *optional_string_storage } };
             },
             [&](Utf32View) {
@@ -392,16 +392,16 @@ public:
         return view;
     }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
         return m_view.visit(
-            [](StringView view) { return view.to_deprecated_string(); },
-            [](Utf16View view) { return view.to_deprecated_string(Utf16View::AllowInvalidCodeUnits::Yes).release_value_but_fixme_should_propagate_errors(); },
+            [](StringView view) { return view.to_byte_string(); },
+            [](Utf16View view) { return view.to_byte_string(Utf16View::AllowInvalidCodeUnits::Yes).release_value_but_fixme_should_propagate_errors(); },
             [](auto& view) {
                 StringBuilder builder;
                 for (auto it = view.begin(); it != view.end(); ++it)
                     builder.append_code_point(*it);
-                return builder.to_deprecated_string();
+                return builder.to_byte_string();
             });
     }
 
@@ -481,17 +481,17 @@ public:
     bool operator==(char const* cstring) const
     {
         return m_view.visit(
-            [&](Utf32View) { return to_deprecated_string() == cstring; },
-            [&](Utf16View) { return to_deprecated_string() == cstring; },
+            [&](Utf32View) { return to_byte_string() == cstring; },
+            [&](Utf16View) { return to_byte_string() == cstring; },
             [&](Utf8View const& view) { return view.as_string() == cstring; },
             [&](StringView view) { return view == cstring; });
     }
 
-    bool operator==(DeprecatedString const& string) const
+    bool operator==(ByteString const& string) const
     {
         return m_view.visit(
-            [&](Utf32View) { return to_deprecated_string() == string; },
-            [&](Utf16View) { return to_deprecated_string() == string; },
+            [&](Utf32View) { return to_byte_string() == string; },
+            [&](Utf16View) { return to_byte_string() == string; },
             [&](Utf8View const& view) { return view.as_string() == string; },
             [&](StringView view) { return view == string; });
     }
@@ -499,8 +499,8 @@ public:
     bool operator==(StringView string) const
     {
         return m_view.visit(
-            [&](Utf32View) { return to_deprecated_string() == string; },
-            [&](Utf16View) { return to_deprecated_string() == string; },
+            [&](Utf32View) { return to_byte_string() == string; },
+            [&](Utf16View) { return to_byte_string() == string; },
             [&](Utf8View const& view) { return view.as_string() == string; },
             [&](StringView view) { return view == string; });
     }
@@ -511,25 +511,25 @@ public:
             [&](Utf32View view) {
                 return view.length() == other.length() && __builtin_memcmp(view.code_points(), other.code_points(), view.length() * sizeof(u32)) == 0;
             },
-            [&](Utf16View) { return to_deprecated_string() == RegexStringView { other }.to_deprecated_string(); },
-            [&](Utf8View const& view) { return view.as_string() == RegexStringView { other }.to_deprecated_string(); },
-            [&](StringView view) { return view == RegexStringView { other }.to_deprecated_string(); });
+            [&](Utf16View) { return to_byte_string() == RegexStringView { other }.to_byte_string(); },
+            [&](Utf8View const& view) { return view.as_string() == RegexStringView { other }.to_byte_string(); },
+            [&](StringView view) { return view == RegexStringView { other }.to_byte_string(); });
     }
 
     bool operator==(Utf16View const& other) const
     {
         return m_view.visit(
-            [&](Utf32View) { return to_deprecated_string() == RegexStringView { other }.to_deprecated_string(); },
+            [&](Utf32View) { return to_byte_string() == RegexStringView { other }.to_byte_string(); },
             [&](Utf16View const& view) { return view == other; },
-            [&](Utf8View const& view) { return view.as_string() == RegexStringView { other }.to_deprecated_string(); },
-            [&](StringView view) { return view == RegexStringView { other }.to_deprecated_string(); });
+            [&](Utf8View const& view) { return view.as_string() == RegexStringView { other }.to_byte_string(); },
+            [&](StringView view) { return view == RegexStringView { other }.to_byte_string(); });
     }
 
     bool operator==(Utf8View const& other) const
     {
         return m_view.visit(
-            [&](Utf32View) { return to_deprecated_string() == other.as_string(); },
-            [&](Utf16View) { return to_deprecated_string() == other.as_string(); },
+            [&](Utf32View) { return to_byte_string() == other.as_string(); },
+            [&](Utf16View) { return to_byte_string() == other.as_string(); },
             [&](Utf8View const& view) { return view.as_string() == other.as_string(); },
             [&](StringView view) { return other.as_string() == view; });
     }
@@ -620,7 +620,7 @@ public:
     {
     }
 
-    Match(DeprecatedString string_, size_t const line_, size_t const column_, size_t const global_offset_)
+    Match(ByteString string_, size_t const line_, size_t const column_, size_t const global_offset_)
         : string(move(string_))
         , view(string.value().view())
         , line(line_)
@@ -700,7 +700,7 @@ template<>
 struct AK::Formatter<regex::RegexStringView> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, regex::RegexStringView value)
     {
-        auto string = value.to_deprecated_string();
+        auto string = value.to_byte_string();
         return Formatter<StringView>::format(builder, string);
     }
 };
diff --git a/Userland/Libraries/LibRegex/RegexMatcher.cpp b/Userland/Libraries/LibRegex/RegexMatcher.cpp
index b91b31f7260..b4b9910b9e0 100644
--- a/Userland/Libraries/LibRegex/RegexMatcher.cpp
+++ b/Userland/Libraries/LibRegex/RegexMatcher.cpp
@@ -5,8 +5,8 @@
  */
 
 #include <AK/BumpAllocator.h>
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/StringBuilder.h>
 #include <LibRegex/RegexMatcher.h>
 #include <LibRegex/RegexParser.h>
@@ -31,7 +31,7 @@ regex::Parser::Result Regex<Parser>::parse_pattern(StringView pattern, typename
 }
 
 template<class Parser>
-Regex<Parser>::Regex(DeprecatedString pattern, typename ParserTraits<Parser>::OptionsType regex_options)
+Regex<Parser>::Regex(ByteString pattern, typename ParserTraits<Parser>::OptionsType regex_options)
     : pattern_value(move(pattern))
 {
     regex::Lexer lexer(pattern_value);
@@ -45,7 +45,7 @@ Regex<Parser>::Regex(DeprecatedString pattern, typename ParserTraits<Parser>::Op
 }
 
 template<class Parser>
-Regex<Parser>::Regex(regex::Parser::Result parse_result, DeprecatedString pattern, typename ParserTraits<Parser>::OptionsType regex_options)
+Regex<Parser>::Regex(regex::Parser::Result parse_result, ByteString pattern, typename ParserTraits<Parser>::OptionsType regex_options)
     : pattern_value(move(pattern))
     , parser_result(move(parse_result))
 {
@@ -87,7 +87,7 @@ typename ParserTraits<Parser>::OptionsType Regex<Parser>::options() const
 }
 
 template<class Parser>
-DeprecatedString Regex<Parser>::error_string(Optional<DeprecatedString> message) const
+ByteString Regex<Parser>::error_string(Optional<ByteString> message) const
 {
     StringBuilder eb;
     eb.append("Error during parsing of regular expression:\n"sv);
@@ -96,7 +96,7 @@ DeprecatedString Regex<Parser>::error_string(Optional<DeprecatedString> message)
         eb.append(' ');
 
     eb.appendff("^---- {}", message.value_or(get_error_string(parser_result.error)));
-    return eb.to_deprecated_string();
+    return eb.to_byte_string();
 }
 
 template<typename Parser>
@@ -169,7 +169,7 @@ RegexResult Matcher<Parser>::match(Vector<RegexStringView> const& views, Optiona
 
         VERIFY(start_position + state.string_position - start_position <= input.view.length());
         if (input.regex_options.has_flag_set(AllFlags::StringCopyMatches)) {
-            state.matches.at(input.match_index) = { input.view.substring_view(start_position, state.string_position - start_position).to_deprecated_string(), input.line, start_position, input.global_offset + start_position };
+            state.matches.at(input.match_index) = { input.view.substring_view(start_position, state.string_position - start_position).to_byte_string(), input.line, start_position, input.global_offset + start_position };
         } else { // let the view point to the original string ...
             state.matches.at(input.match_index) = { input.view.substring_view(start_position, state.string_position - start_position), input.line, start_position, input.global_offset + start_position };
         }
diff --git a/Userland/Libraries/LibRegex/RegexMatcher.h b/Userland/Libraries/LibRegex/RegexMatcher.h
index 7f1ef652c32..6554447afd3 100644
--- a/Userland/Libraries/LibRegex/RegexMatcher.h
+++ b/Userland/Libraries/LibRegex/RegexMatcher.h
@@ -82,21 +82,21 @@ private:
 template<class Parser>
 class Regex final {
 public:
-    DeprecatedString pattern_value;
+    ByteString pattern_value;
     regex::Parser::Result parser_result;
     OwnPtr<Matcher<Parser>> matcher { nullptr };
     mutable size_t start_offset { 0 };
 
     static regex::Parser::Result parse_pattern(StringView pattern, typename ParserTraits<Parser>::OptionsType regex_options = {});
 
-    explicit Regex(DeprecatedString pattern, typename ParserTraits<Parser>::OptionsType regex_options = {});
-    Regex(regex::Parser::Result parse_result, DeprecatedString pattern, typename ParserTraits<Parser>::OptionsType regex_options = {});
+    explicit Regex(ByteString pattern, typename ParserTraits<Parser>::OptionsType regex_options = {});
+    Regex(regex::Parser::Result parse_result, ByteString pattern, typename ParserTraits<Parser>::OptionsType regex_options = {});
     ~Regex() = default;
     Regex(Regex&&);
     Regex& operator=(Regex&&);
 
     typename ParserTraits<Parser>::OptionsType options() const;
-    DeprecatedString error_string(Optional<DeprecatedString> message = {}) const;
+    ByteString error_string(Optional<ByteString> message = {}) const;
 
     RegexResult match(RegexStringView view, Optional<typename ParserTraits<Parser>::OptionsType> regex_options = {}) const
     {
@@ -112,7 +112,7 @@ public:
         return matcher->match(views, regex_options);
     }
 
-    DeprecatedString replace(RegexStringView view, StringView replacement_pattern, Optional<typename ParserTraits<Parser>::OptionsType> regex_options = {}) const
+    ByteString replace(RegexStringView view, StringView replacement_pattern, Optional<typename ParserTraits<Parser>::OptionsType> regex_options = {}) const
     {
         if (!matcher || parser_result.error != Error::NoError)
             return {};
@@ -121,11 +121,11 @@ public:
         size_t start_offset = 0;
         RegexResult result = matcher->match(view, regex_options);
         if (!result.success)
-            return view.to_deprecated_string();
+            return view.to_byte_string();
 
         for (size_t i = 0; i < result.matches.size(); ++i) {
             auto& match = result.matches[i];
-            builder.append(view.substring_view(start_offset, match.global_offset - start_offset).to_deprecated_string());
+            builder.append(view.substring_view(start_offset, match.global_offset - start_offset).to_byte_string());
             start_offset = match.global_offset + match.view.length();
             GenericLexer lexer(replacement_pattern);
             while (!lexer.is_eof()) {
@@ -136,7 +136,7 @@ public:
                     }
                     auto number = lexer.consume_while(isdigit);
                     if (auto index = number.to_uint(); index.has_value() && result.n_capture_groups >= index.value()) {
-                        builder.append(result.capture_group_matches[i][index.value() - 1].view.to_deprecated_string());
+                        builder.append(result.capture_group_matches[i][index.value() - 1].view.to_byte_string());
                     } else {
                         builder.appendff("\\{}", number);
                     }
@@ -146,9 +146,9 @@ public:
             }
         }
 
-        builder.append(view.substring_view(start_offset, view.length() - start_offset).to_deprecated_string());
+        builder.append(view.substring_view(start_offset, view.length() - start_offset).to_byte_string());
 
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 
     // FIXME: replace(Vector<RegexStringView> const , ...)
diff --git a/Userland/Libraries/LibRegex/RegexOptimizer.cpp b/Userland/Libraries/LibRegex/RegexOptimizer.cpp
index 5da5375008d..914821ce27d 100644
--- a/Userland/Libraries/LibRegex/RegexOptimizer.cpp
+++ b/Userland/Libraries/LibRegex/RegexOptimizer.cpp
@@ -568,7 +568,7 @@ bool Regex<Parser>::attempt_rewrite_entire_match_as_substring_search(BasicBlockL
         state.instruction_position += opcode.size();
     }
 
-    parser_result.optimization_data.pure_substring_search = final_string.to_deprecated_string();
+    parser_result.optimization_data.pure_substring_search = final_string.to_byte_string();
     return true;
 }
 
@@ -960,10 +960,10 @@ void Optimizer::append_alternation(ByteCode& target, Span<ByteCode> alternatives
 
     if constexpr (REGEX_DEBUG) {
         Function<void(decltype(trie)&, size_t)> print_tree = [&](decltype(trie)& node, size_t indent = 0) mutable {
-            DeprecatedString name = "(no ip)";
-            DeprecatedString insn;
+            ByteString name = "(no ip)";
+            ByteString insn;
             if (node.has_metadata()) {
-                name = DeprecatedString::formatted(
+                name = ByteString::formatted(
                     "{}@{} ({} node{})",
                     node.metadata_value().first().instruction_position,
                     node.metadata_value().first().alternative_index,
@@ -973,7 +973,7 @@ void Optimizer::append_alternation(ByteCode& target, Span<ByteCode> alternatives
                 MatchState state;
                 state.instruction_position = node.metadata_value().first().instruction_position;
                 auto& opcode = alternatives[node.metadata_value().first().alternative_index].get_opcode(state);
-                insn = DeprecatedString::formatted("{} {}", opcode.to_deprecated_string(), opcode.arguments_string());
+                insn = ByteString::formatted("{} {}", opcode.to_byte_string(), opcode.arguments_string());
             }
             dbgln("{:->{}}| {} -- {}", "", indent * 2, name, insn);
             for (auto& child : node.children())
diff --git a/Userland/Libraries/LibRegex/RegexParser.cpp b/Userland/Libraries/LibRegex/RegexParser.cpp
index 38632fdfc47..c5d4073bf7d 100644
--- a/Userland/Libraries/LibRegex/RegexParser.cpp
+++ b/Userland/Libraries/LibRegex/RegexParser.cpp
@@ -8,9 +8,9 @@
 #include "RegexParser.h"
 #include "RegexDebug.h"
 #include <AK/AnyOf.h>
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/GenericLexer.h>
 #include <AK/ScopeGuard.h>
 #include <AK/StringBuilder.h>
@@ -75,7 +75,7 @@ ALWAYS_INLINE Token Parser::consume(TokenType type, Error error)
     return consume();
 }
 
-ALWAYS_INLINE bool Parser::consume(DeprecatedString const& str)
+ALWAYS_INLINE bool Parser::consume(ByteString const& str)
 {
     size_t potentially_go_back { 1 };
     for (auto ch : str) {
@@ -615,7 +615,7 @@ ALWAYS_INLINE bool PosixExtendedParser::parse_repetition_symbol(ByteCode& byteco
             number_builder.append(consume().value());
         }
 
-        auto maybe_minimum = number_builder.to_deprecated_string().to_uint();
+        auto maybe_minimum = number_builder.to_byte_string().to_uint();
         if (!maybe_minimum.has_value())
             return set_error(Error::InvalidBraceContent);
 
@@ -644,7 +644,7 @@ ALWAYS_INLINE bool PosixExtendedParser::parse_repetition_symbol(ByteCode& byteco
             number_builder.append(consume().value());
         }
         if (!number_builder.is_empty()) {
-            auto value = number_builder.to_deprecated_string().to_uint();
+            auto value = number_builder.to_byte_string().to_uint();
             if (!value.has_value() || minimum > value.value() || *value > s_maximum_repetition_count)
                 return set_error(Error::InvalidBraceContent);
 
@@ -2560,7 +2560,7 @@ DeprecatedFlyString ECMA262Parser::read_capture_group_specifier(bool take_starti
         builder.append_code_point(code_point);
     }
 
-    DeprecatedFlyString name = builder.to_deprecated_string();
+    DeprecatedFlyString name = builder.to_byte_string();
     if (!hit_end || name.is_empty())
         set_error(Error::InvalidNameForCaptureGroup);
 
diff --git a/Userland/Libraries/LibRegex/RegexParser.h b/Userland/Libraries/LibRegex/RegexParser.h
index d2923484ed6..bb01ce56423 100644
--- a/Userland/Libraries/LibRegex/RegexParser.h
+++ b/Userland/Libraries/LibRegex/RegexParser.h
@@ -57,7 +57,7 @@ public:
         AllOptions options;
 
         struct {
-            Optional<DeprecatedString> pure_substring_search;
+            Optional<ByteString> pure_substring_search;
         } optimization_data {};
     };
 
@@ -86,7 +86,7 @@ protected:
     ALWAYS_INLINE bool match_ordinary_characters();
     ALWAYS_INLINE Token consume();
     ALWAYS_INLINE Token consume(TokenType type, Error error);
-    ALWAYS_INLINE bool consume(DeprecatedString const&);
+    ALWAYS_INLINE bool consume(ByteString const&);
     ALWAYS_INLINE Optional<u32> consume_escaped_code_point(bool unicode);
     ALWAYS_INLINE bool try_skip(StringView);
     ALWAYS_INLINE bool lookahead_any(StringView);
diff --git a/Userland/Libraries/LibSQL/AST/AST.h b/Userland/Libraries/LibSQL/AST/AST.h
index 639609594a0..e007c93cdc6 100644
--- a/Userland/Libraries/LibSQL/AST/AST.h
+++ b/Userland/Libraries/LibSQL/AST/AST.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefCounted.h>
 #include <AK/RefPtr.h>
@@ -54,53 +54,53 @@ private:
 
 class TypeName : public ASTNode {
 public:
-    TypeName(DeprecatedString name, Vector<NonnullRefPtr<SignedNumber>> signed_numbers)
+    TypeName(ByteString name, Vector<NonnullRefPtr<SignedNumber>> signed_numbers)
         : m_name(move(name))
         , m_signed_numbers(move(signed_numbers))
     {
         VERIFY(m_signed_numbers.size() <= 2);
     }
 
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
     Vector<NonnullRefPtr<SignedNumber>> const& signed_numbers() const { return m_signed_numbers; }
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
     Vector<NonnullRefPtr<SignedNumber>> m_signed_numbers;
 };
 
 class ColumnDefinition : public ASTNode {
 public:
-    ColumnDefinition(DeprecatedString name, NonnullRefPtr<TypeName> type_name)
+    ColumnDefinition(ByteString name, NonnullRefPtr<TypeName> type_name)
         : m_name(move(name))
         , m_type_name(move(type_name))
     {
     }
 
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
     NonnullRefPtr<TypeName> const& type_name() const { return m_type_name; }
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
     NonnullRefPtr<TypeName> m_type_name;
 };
 
 class CommonTableExpression : public ASTNode {
 public:
-    CommonTableExpression(DeprecatedString table_name, Vector<DeprecatedString> column_names, NonnullRefPtr<Select> select_statement)
+    CommonTableExpression(ByteString table_name, Vector<ByteString> column_names, NonnullRefPtr<Select> select_statement)
         : m_table_name(move(table_name))
         , m_column_names(move(column_names))
         , m_select_statement(move(select_statement))
     {
     }
 
-    DeprecatedString const& table_name() const { return m_table_name; }
-    Vector<DeprecatedString> const& column_names() const { return m_column_names; }
+    ByteString const& table_name() const { return m_table_name; }
+    Vector<ByteString> const& column_names() const { return m_column_names; }
     NonnullRefPtr<Select> const& select_statement() const { return m_select_statement; }
 
 private:
-    DeprecatedString m_table_name;
-    Vector<DeprecatedString> m_column_names;
+    ByteString m_table_name;
+    Vector<ByteString> m_column_names;
     NonnullRefPtr<Select> m_select_statement;
 };
 
@@ -123,28 +123,28 @@ private:
 
 class QualifiedTableName : public ASTNode {
 public:
-    QualifiedTableName(DeprecatedString schema_name, DeprecatedString table_name, DeprecatedString alias)
+    QualifiedTableName(ByteString schema_name, ByteString table_name, ByteString alias)
         : m_schema_name(move(schema_name))
         , m_table_name(move(table_name))
         , m_alias(move(alias))
     {
     }
 
-    DeprecatedString const& schema_name() const { return m_schema_name; }
-    DeprecatedString const& table_name() const { return m_table_name; }
-    DeprecatedString const& alias() const { return m_alias; }
+    ByteString const& schema_name() const { return m_schema_name; }
+    ByteString const& table_name() const { return m_table_name; }
+    ByteString const& alias() const { return m_alias; }
 
 private:
-    DeprecatedString m_schema_name;
-    DeprecatedString m_table_name;
-    DeprecatedString m_alias;
+    ByteString m_schema_name;
+    ByteString m_table_name;
+    ByteString m_alias;
 };
 
 class ReturningClause : public ASTNode {
 public:
     struct ColumnClause {
         NonnullRefPtr<Expression> expression;
-        DeprecatedString column_alias;
+        ByteString column_alias;
     };
 
     ReturningClause() = default;
@@ -171,13 +171,13 @@ class ResultColumn : public ASTNode {
 public:
     ResultColumn() = default;
 
-    explicit ResultColumn(DeprecatedString table_name)
+    explicit ResultColumn(ByteString table_name)
         : m_type(ResultType::Table)
         , m_table_name(move(table_name))
     {
     }
 
-    ResultColumn(NonnullRefPtr<Expression> expression, DeprecatedString column_alias)
+    ResultColumn(NonnullRefPtr<Expression> expression, ByteString column_alias)
         : m_type(ResultType::Expression)
         , m_expression(move(expression))
         , m_column_alias(move(column_alias))
@@ -187,19 +187,19 @@ public:
     ResultType type() const { return m_type; }
 
     bool select_from_table() const { return m_table_name.has_value(); }
-    Optional<DeprecatedString> const& table_name() const { return m_table_name; }
+    Optional<ByteString> const& table_name() const { return m_table_name; }
 
     bool select_from_expression() const { return !m_expression.is_null(); }
     RefPtr<Expression> const& expression() const { return m_expression; }
-    DeprecatedString const& column_alias() const { return m_column_alias; }
+    ByteString const& column_alias() const { return m_column_alias; }
 
 private:
     ResultType m_type { ResultType::All };
 
-    Optional<DeprecatedString> m_table_name {};
+    Optional<ByteString> m_table_name {};
 
     RefPtr<Expression> m_expression {};
-    DeprecatedString m_column_alias {};
+    ByteString m_column_alias {};
 };
 
 class GroupByClause : public ASTNode {
@@ -223,7 +223,7 @@ class TableOrSubquery : public ASTNode {
 public:
     TableOrSubquery() = default;
 
-    TableOrSubquery(DeprecatedString schema_name, DeprecatedString table_name, DeprecatedString table_alias)
+    TableOrSubquery(ByteString schema_name, ByteString table_name, ByteString table_alias)
         : m_is_table(true)
         , m_schema_name(move(schema_name))
         , m_table_name(move(table_name))
@@ -238,18 +238,18 @@ public:
     }
 
     bool is_table() const { return m_is_table; }
-    DeprecatedString const& schema_name() const { return m_schema_name; }
-    DeprecatedString const& table_name() const { return m_table_name; }
-    DeprecatedString const& table_alias() const { return m_table_alias; }
+    ByteString const& schema_name() const { return m_schema_name; }
+    ByteString const& table_name() const { return m_table_name; }
+    ByteString const& table_alias() const { return m_table_alias; }
 
     bool is_subquery() const { return m_is_subquery; }
     Vector<NonnullRefPtr<TableOrSubquery>> const& subqueries() const { return m_subqueries; }
 
 private:
     bool m_is_table { false };
-    DeprecatedString m_schema_name {};
-    DeprecatedString m_table_name {};
-    DeprecatedString m_table_alias {};
+    ByteString m_schema_name {};
+    ByteString m_table_name {};
+    ByteString m_table_alias {};
 
     bool m_is_subquery { false };
     Vector<NonnullRefPtr<TableOrSubquery>> m_subqueries {};
@@ -257,7 +257,7 @@ private:
 
 class OrderingTerm : public ASTNode {
 public:
-    OrderingTerm(NonnullRefPtr<Expression> expression, DeprecatedString collation_name, Order order, Nulls nulls)
+    OrderingTerm(NonnullRefPtr<Expression> expression, ByteString collation_name, Order order, Nulls nulls)
         : m_expression(move(expression))
         , m_collation_name(move(collation_name))
         , m_order(order)
@@ -266,13 +266,13 @@ public:
     }
 
     NonnullRefPtr<Expression> const& expression() const { return m_expression; }
-    DeprecatedString const& collation_name() const { return m_collation_name; }
+    ByteString const& collation_name() const { return m_collation_name; }
     Order order() const { return m_order; }
     Nulls nulls() const { return m_nulls; }
 
 private:
     NonnullRefPtr<Expression> m_expression;
-    DeprecatedString m_collation_name;
+    ByteString m_collation_name;
     Order m_order;
     Nulls m_nulls;
 };
@@ -331,29 +331,29 @@ private:
 
 class StringLiteral : public Expression {
 public:
-    explicit StringLiteral(DeprecatedString value)
+    explicit StringLiteral(ByteString value)
         : m_value(move(value))
     {
     }
 
-    DeprecatedString const& value() const { return m_value; }
+    ByteString const& value() const { return m_value; }
     virtual ResultOr<Value> evaluate(ExecutionContext&) const override;
 
 private:
-    DeprecatedString m_value;
+    ByteString m_value;
 };
 
 class BlobLiteral : public Expression {
 public:
-    explicit BlobLiteral(DeprecatedString value)
+    explicit BlobLiteral(ByteString value)
         : m_value(move(value))
     {
     }
 
-    DeprecatedString const& value() const { return m_value; }
+    ByteString const& value() const { return m_value; }
 
 private:
-    DeprecatedString m_value;
+    ByteString m_value;
 };
 
 class BooleanLiteral : public Expression {
@@ -455,22 +455,22 @@ private:
 
 class ColumnNameExpression : public Expression {
 public:
-    ColumnNameExpression(DeprecatedString schema_name, DeprecatedString table_name, DeprecatedString column_name)
+    ColumnNameExpression(ByteString schema_name, ByteString table_name, ByteString column_name)
         : m_schema_name(move(schema_name))
         , m_table_name(move(table_name))
         , m_column_name(move(column_name))
     {
     }
 
-    DeprecatedString const& schema_name() const { return m_schema_name; }
-    DeprecatedString const& table_name() const { return m_table_name; }
-    DeprecatedString const& column_name() const { return m_column_name; }
+    ByteString const& schema_name() const { return m_schema_name; }
+    ByteString const& table_name() const { return m_table_name; }
+    ByteString const& column_name() const { return m_column_name; }
     virtual ResultOr<Value> evaluate(ExecutionContext&) const override;
 
 private:
-    DeprecatedString m_schema_name;
-    DeprecatedString m_table_name;
-    DeprecatedString m_column_name;
+    ByteString m_schema_name;
+    ByteString m_table_name;
+    ByteString m_column_name;
 };
 
 #define __enum_UnaryOperator(S) \
@@ -641,16 +641,16 @@ private:
 
 class CollateExpression : public NestedExpression {
 public:
-    CollateExpression(NonnullRefPtr<Expression> expression, DeprecatedString collation_name)
+    CollateExpression(NonnullRefPtr<Expression> expression, ByteString collation_name)
         : NestedExpression(move(expression))
         , m_collation_name(move(collation_name))
     {
     }
 
-    DeprecatedString const& collation_name() const { return m_collation_name; }
+    ByteString const& collation_name() const { return m_collation_name; }
 
 private:
-    DeprecatedString m_collation_name;
+    ByteString m_collation_name;
 };
 
 enum class MatchOperator {
@@ -738,19 +738,19 @@ private:
 
 class InTableExpression : public InvertibleNestedExpression {
 public:
-    InTableExpression(NonnullRefPtr<Expression> expression, DeprecatedString schema_name, DeprecatedString table_name, bool invert_expression)
+    InTableExpression(NonnullRefPtr<Expression> expression, ByteString schema_name, ByteString table_name, bool invert_expression)
         : InvertibleNestedExpression(move(expression), invert_expression)
         , m_schema_name(move(schema_name))
         , m_table_name(move(table_name))
     {
     }
 
-    DeprecatedString const& schema_name() const { return m_schema_name; }
-    DeprecatedString const& table_name() const { return m_table_name; }
+    ByteString const& schema_name() const { return m_schema_name; }
+    ByteString const& table_name() const { return m_table_name; }
 
 private:
-    DeprecatedString m_schema_name;
-    DeprecatedString m_table_name;
+    ByteString m_schema_name;
+    ByteString m_table_name;
 };
 
 //==================================================================================================
@@ -772,25 +772,25 @@ class ErrorStatement final : public Statement {
 
 class CreateSchema : public Statement {
 public:
-    CreateSchema(DeprecatedString schema_name, bool is_error_if_schema_exists)
+    CreateSchema(ByteString schema_name, bool is_error_if_schema_exists)
         : m_schema_name(move(schema_name))
         , m_is_error_if_schema_exists(is_error_if_schema_exists)
     {
     }
 
-    DeprecatedString const& schema_name() const { return m_schema_name; }
+    ByteString const& schema_name() const { return m_schema_name; }
     bool is_error_if_schema_exists() const { return m_is_error_if_schema_exists; }
 
     ResultOr<ResultSet> execute(ExecutionContext&) const override;
 
 private:
-    DeprecatedString m_schema_name;
+    ByteString m_schema_name;
     bool m_is_error_if_schema_exists;
 };
 
 class CreateTable : public Statement {
 public:
-    CreateTable(DeprecatedString schema_name, DeprecatedString table_name, RefPtr<Select> select_statement, bool is_temporary, bool is_error_if_table_exists)
+    CreateTable(ByteString schema_name, ByteString table_name, RefPtr<Select> select_statement, bool is_temporary, bool is_error_if_table_exists)
         : m_schema_name(move(schema_name))
         , m_table_name(move(table_name))
         , m_select_statement(move(select_statement))
@@ -799,7 +799,7 @@ public:
     {
     }
 
-    CreateTable(DeprecatedString schema_name, DeprecatedString table_name, Vector<NonnullRefPtr<ColumnDefinition>> columns, bool is_temporary, bool is_error_if_table_exists)
+    CreateTable(ByteString schema_name, ByteString table_name, Vector<NonnullRefPtr<ColumnDefinition>> columns, bool is_temporary, bool is_error_if_table_exists)
         : m_schema_name(move(schema_name))
         , m_table_name(move(table_name))
         , m_columns(move(columns))
@@ -808,8 +808,8 @@ public:
     {
     }
 
-    DeprecatedString const& schema_name() const { return m_schema_name; }
-    DeprecatedString const& table_name() const { return m_table_name; }
+    ByteString const& schema_name() const { return m_schema_name; }
+    ByteString const& table_name() const { return m_table_name; }
 
     bool has_selection() const { return !m_select_statement.is_null(); }
     RefPtr<Select> const& select_statement() const { return m_select_statement; }
@@ -823,8 +823,8 @@ public:
     ResultOr<ResultSet> execute(ExecutionContext&) const override;
 
 private:
-    DeprecatedString m_schema_name;
-    DeprecatedString m_table_name;
+    ByteString m_schema_name;
+    ByteString m_table_name;
     RefPtr<Select> m_select_statement;
     Vector<NonnullRefPtr<ColumnDefinition>> m_columns;
     bool m_is_temporary;
@@ -833,55 +833,55 @@ private:
 
 class AlterTable : public Statement {
 public:
-    DeprecatedString const& schema_name() const { return m_schema_name; }
-    DeprecatedString const& table_name() const { return m_table_name; }
+    ByteString const& schema_name() const { return m_schema_name; }
+    ByteString const& table_name() const { return m_table_name; }
 
 protected:
-    AlterTable(DeprecatedString schema_name, DeprecatedString table_name)
+    AlterTable(ByteString schema_name, ByteString table_name)
         : m_schema_name(move(schema_name))
         , m_table_name(move(table_name))
     {
     }
 
 private:
-    DeprecatedString m_schema_name;
-    DeprecatedString m_table_name;
+    ByteString m_schema_name;
+    ByteString m_table_name;
 };
 
 class RenameTable : public AlterTable {
 public:
-    RenameTable(DeprecatedString schema_name, DeprecatedString table_name, DeprecatedString new_table_name)
+    RenameTable(ByteString schema_name, ByteString table_name, ByteString new_table_name)
         : AlterTable(move(schema_name), move(table_name))
         , m_new_table_name(move(new_table_name))
     {
     }
 
-    DeprecatedString const& new_table_name() const { return m_new_table_name; }
+    ByteString const& new_table_name() const { return m_new_table_name; }
 
 private:
-    DeprecatedString m_new_table_name;
+    ByteString m_new_table_name;
 };
 
 class RenameColumn : public AlterTable {
 public:
-    RenameColumn(DeprecatedString schema_name, DeprecatedString table_name, DeprecatedString column_name, DeprecatedString new_column_name)
+    RenameColumn(ByteString schema_name, ByteString table_name, ByteString column_name, ByteString new_column_name)
         : AlterTable(move(schema_name), move(table_name))
         , m_column_name(move(column_name))
         , m_new_column_name(move(new_column_name))
     {
     }
 
-    DeprecatedString const& column_name() const { return m_column_name; }
-    DeprecatedString const& new_column_name() const { return m_new_column_name; }
+    ByteString const& column_name() const { return m_column_name; }
+    ByteString const& new_column_name() const { return m_new_column_name; }
 
 private:
-    DeprecatedString m_column_name;
-    DeprecatedString m_new_column_name;
+    ByteString m_column_name;
+    ByteString m_new_column_name;
 };
 
 class AddColumn : public AlterTable {
 public:
-    AddColumn(DeprecatedString schema_name, DeprecatedString table_name, NonnullRefPtr<ColumnDefinition> column)
+    AddColumn(ByteString schema_name, ByteString table_name, NonnullRefPtr<ColumnDefinition> column)
         : AlterTable(move(schema_name), move(table_name))
         , m_column(move(column))
     {
@@ -895,34 +895,34 @@ private:
 
 class DropColumn : public AlterTable {
 public:
-    DropColumn(DeprecatedString schema_name, DeprecatedString table_name, DeprecatedString column_name)
+    DropColumn(ByteString schema_name, ByteString table_name, ByteString column_name)
         : AlterTable(move(schema_name), move(table_name))
         , m_column_name(move(column_name))
     {
     }
 
-    DeprecatedString const& column_name() const { return m_column_name; }
+    ByteString const& column_name() const { return m_column_name; }
 
 private:
-    DeprecatedString m_column_name;
+    ByteString m_column_name;
 };
 
 class DropTable : public Statement {
 public:
-    DropTable(DeprecatedString schema_name, DeprecatedString table_name, bool is_error_if_table_does_not_exist)
+    DropTable(ByteString schema_name, ByteString table_name, bool is_error_if_table_does_not_exist)
         : m_schema_name(move(schema_name))
         , m_table_name(move(table_name))
         , m_is_error_if_table_does_not_exist(is_error_if_table_does_not_exist)
     {
     }
 
-    DeprecatedString const& schema_name() const { return m_schema_name; }
-    DeprecatedString const& table_name() const { return m_table_name; }
+    ByteString const& schema_name() const { return m_schema_name; }
+    ByteString const& table_name() const { return m_table_name; }
     bool is_error_if_table_does_not_exist() const { return m_is_error_if_table_does_not_exist; }
 
 private:
-    DeprecatedString m_schema_name;
-    DeprecatedString m_table_name;
+    ByteString m_schema_name;
+    ByteString m_table_name;
     bool m_is_error_if_table_does_not_exist;
 };
 
@@ -936,7 +936,7 @@ enum class ConflictResolution {
 
 class Insert : public Statement {
 public:
-    Insert(RefPtr<CommonTableExpressionList> common_table_expression_list, ConflictResolution conflict_resolution, DeprecatedString schema_name, DeprecatedString table_name, DeprecatedString alias, Vector<DeprecatedString> column_names, Vector<NonnullRefPtr<ChainedExpression>> chained_expressions)
+    Insert(RefPtr<CommonTableExpressionList> common_table_expression_list, ConflictResolution conflict_resolution, ByteString schema_name, ByteString table_name, ByteString alias, Vector<ByteString> column_names, Vector<NonnullRefPtr<ChainedExpression>> chained_expressions)
         : m_common_table_expression_list(move(common_table_expression_list))
         , m_conflict_resolution(conflict_resolution)
         , m_schema_name(move(schema_name))
@@ -947,7 +947,7 @@ public:
     {
     }
 
-    Insert(RefPtr<CommonTableExpressionList> common_table_expression_list, ConflictResolution conflict_resolution, DeprecatedString schema_name, DeprecatedString table_name, DeprecatedString alias, Vector<DeprecatedString> column_names, RefPtr<Select> select_statement)
+    Insert(RefPtr<CommonTableExpressionList> common_table_expression_list, ConflictResolution conflict_resolution, ByteString schema_name, ByteString table_name, ByteString alias, Vector<ByteString> column_names, RefPtr<Select> select_statement)
         : m_common_table_expression_list(move(common_table_expression_list))
         , m_conflict_resolution(conflict_resolution)
         , m_schema_name(move(schema_name))
@@ -958,7 +958,7 @@ public:
     {
     }
 
-    Insert(RefPtr<CommonTableExpressionList> common_table_expression_list, ConflictResolution conflict_resolution, DeprecatedString schema_name, DeprecatedString table_name, DeprecatedString alias, Vector<DeprecatedString> column_names)
+    Insert(RefPtr<CommonTableExpressionList> common_table_expression_list, ConflictResolution conflict_resolution, ByteString schema_name, ByteString table_name, ByteString alias, Vector<ByteString> column_names)
         : m_common_table_expression_list(move(common_table_expression_list))
         , m_conflict_resolution(conflict_resolution)
         , m_schema_name(move(schema_name))
@@ -970,10 +970,10 @@ public:
 
     RefPtr<CommonTableExpressionList> const& common_table_expression_list() const { return m_common_table_expression_list; }
     ConflictResolution conflict_resolution() const { return m_conflict_resolution; }
-    DeprecatedString const& schema_name() const { return m_schema_name; }
-    DeprecatedString const& table_name() const { return m_table_name; }
-    DeprecatedString const& alias() const { return m_alias; }
-    Vector<DeprecatedString> const& column_names() const { return m_column_names; }
+    ByteString const& schema_name() const { return m_schema_name; }
+    ByteString const& table_name() const { return m_table_name; }
+    ByteString const& alias() const { return m_alias; }
+    Vector<ByteString> const& column_names() const { return m_column_names; }
 
     bool default_values() const { return !has_expressions() && !has_selection(); }
 
@@ -988,10 +988,10 @@ public:
 private:
     RefPtr<CommonTableExpressionList> m_common_table_expression_list;
     ConflictResolution m_conflict_resolution;
-    DeprecatedString m_schema_name;
-    DeprecatedString m_table_name;
-    DeprecatedString m_alias;
-    Vector<DeprecatedString> m_column_names;
+    ByteString m_schema_name;
+    ByteString m_table_name;
+    ByteString m_alias;
+    Vector<ByteString> m_column_names;
     Vector<NonnullRefPtr<ChainedExpression>> m_chained_expressions;
     RefPtr<Select> m_select_statement;
 };
@@ -999,7 +999,7 @@ private:
 class Update : public Statement {
 public:
     struct UpdateColumns {
-        Vector<DeprecatedString> column_names;
+        Vector<ByteString> column_names;
         NonnullRefPtr<Expression> expression;
     };
 
diff --git a/Userland/Libraries/LibSQL/AST/Expression.cpp b/Userland/Libraries/LibSQL/AST/Expression.cpp
index 9bdb71b86c8..f032aed1e8c 100644
--- a/Userland/Libraries/LibSQL/AST/Expression.cpp
+++ b/Userland/Libraries/LibSQL/AST/Expression.cpp
@@ -68,9 +68,9 @@ ResultOr<Value> BinaryOperatorExpression::evaluate(ExecutionContext& context) co
             return Result { SQLCommand::Unknown, SQLErrorCode::BooleanOperatorTypeMismatch, BinaryOperator_name(type()) };
 
         AK::StringBuilder builder;
-        builder.append(lhs_value.to_deprecated_string());
-        builder.append(rhs_value.to_deprecated_string());
-        return Value(builder.to_deprecated_string());
+        builder.append(lhs_value.to_byte_string());
+        builder.append(rhs_value.to_byte_string());
+        return Value(builder.to_byte_string());
     }
     case BinaryOperator::Multiplication:
         return lhs_value.multiply(rhs_value);
@@ -181,7 +181,7 @@ ResultOr<Value> MatchExpression::evaluate(ExecutionContext& context) const
 
         char escape_char = '\0';
         if (escape()) {
-            auto escape_str = TRY(escape()->evaluate(context)).to_deprecated_string();
+            auto escape_str = TRY(escape()->evaluate(context)).to_byte_string();
             if (escape_str.length() != 1)
                 return Result { SQLCommand::Unknown, SQLErrorCode::SyntaxError, "ESCAPE should be a single character" };
             escape_char = escape_str[0];
@@ -192,7 +192,7 @@ ResultOr<Value> MatchExpression::evaluate(ExecutionContext& context) const
         bool escaped = false;
         AK::StringBuilder builder;
         builder.append('^');
-        for (auto c : rhs_value.to_deprecated_string()) {
+        for (auto c : rhs_value.to_byte_string()) {
             if (escape() && c == escape_char && !escaped) {
                 escaped = true;
             } else if (s_posix_basic_metacharacters.contains(c)) {
@@ -211,25 +211,25 @@ ResultOr<Value> MatchExpression::evaluate(ExecutionContext& context) const
         builder.append('$');
 
         // FIXME: We should probably cache this regex.
-        auto regex = Regex<PosixBasic>(builder.to_deprecated_string());
-        auto result = regex.match(lhs_value.to_deprecated_string(), PosixFlags::Insensitive | PosixFlags::Unicode);
+        auto regex = Regex<PosixBasic>(builder.to_byte_string());
+        auto result = regex.match(lhs_value.to_byte_string(), PosixFlags::Insensitive | PosixFlags::Unicode);
         return Value(invert_expression() ? !result.success : result.success);
     }
     case MatchOperator::Regexp: {
         Value lhs_value = TRY(lhs()->evaluate(context));
         Value rhs_value = TRY(rhs()->evaluate(context));
 
-        auto regex = Regex<PosixExtended>(rhs_value.to_deprecated_string());
+        auto regex = Regex<PosixExtended>(rhs_value.to_byte_string());
         auto err = regex.parser_result.error;
         if (err != regex::Error::NoError) {
             StringBuilder builder;
             builder.append("Regular expression: "sv);
             builder.append(get_error_string(err));
 
-            return Result { SQLCommand::Unknown, SQLErrorCode::SyntaxError, builder.to_deprecated_string() };
+            return Result { SQLCommand::Unknown, SQLErrorCode::SyntaxError, builder.to_byte_string() };
         }
 
-        auto result = regex.match(lhs_value.to_deprecated_string(), PosixFlags::Insensitive | PosixFlags::Unicode);
+        auto result = regex.match(lhs_value.to_byte_string(), PosixFlags::Insensitive | PosixFlags::Unicode);
         return Value(invert_expression() ? !result.success : result.success);
     }
     case MatchOperator::Glob:
diff --git a/Userland/Libraries/LibSQL/AST/Insert.cpp b/Userland/Libraries/LibSQL/AST/Insert.cpp
index 43f7e5022fd..233395040a9 100644
--- a/Userland/Libraries/LibSQL/AST/Insert.cpp
+++ b/Userland/Libraries/LibSQL/AST/Insert.cpp
@@ -37,7 +37,7 @@ ResultOr<ResultSet> Insert::execute(ExecutionContext& context) const
         auto values = row_value.to_vector().release_value();
 
         if (m_column_names.is_empty() && values.size() != row.size())
-            return Result { SQLCommand::Insert, SQLErrorCode::InvalidNumberOfValues, DeprecatedString::empty() };
+            return Result { SQLCommand::Insert, SQLErrorCode::InvalidNumberOfValues, ByteString::empty() };
 
         for (auto ix = 0u; ix < values.size(); ix++) {
             auto& tuple_descriptor = *row.descriptor();
diff --git a/Userland/Libraries/LibSQL/AST/Lexer.cpp b/Userland/Libraries/LibSQL/AST/Lexer.cpp
index dfc857ef25c..01ef0c025b8 100644
--- a/Userland/Libraries/LibSQL/AST/Lexer.cpp
+++ b/Userland/Libraries/LibSQL/AST/Lexer.cpp
@@ -11,9 +11,9 @@
 
 namespace SQL::AST {
 
-HashMap<DeprecatedString, TokenType> Lexer::s_keywords;
+HashMap<ByteString, TokenType> Lexer::s_keywords;
 HashMap<char, TokenType> Lexer::s_one_char_tokens;
-HashMap<DeprecatedString, TokenType> Lexer::s_two_char_tokens;
+HashMap<ByteString, TokenType> Lexer::s_two_char_tokens;
 
 Lexer::Lexer(StringView source)
     : m_source(source)
@@ -109,7 +109,7 @@ Token Lexer::next()
         }
     }
 
-    Token token(token_type, current_token.to_deprecated_string(),
+    Token token(token_type, current_token.to_byte_string(),
         { value_start_line_number, value_start_column_number },
         { m_line_number, m_line_column });
 
diff --git a/Userland/Libraries/LibSQL/AST/Lexer.h b/Userland/Libraries/LibSQL/AST/Lexer.h
index 9a0cd0e354f..2cfce615528 100644
--- a/Userland/Libraries/LibSQL/AST/Lexer.h
+++ b/Userland/Libraries/LibSQL/AST/Lexer.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include "Token.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/StringView.h>
 
@@ -46,9 +46,9 @@ private:
     bool is_line_break() const;
     bool is_eof() const;
 
-    static HashMap<DeprecatedString, TokenType> s_keywords;
+    static HashMap<ByteString, TokenType> s_keywords;
     static HashMap<char, TokenType> s_one_char_tokens;
-    static HashMap<DeprecatedString, TokenType> s_two_char_tokens;
+    static HashMap<ByteString, TokenType> s_two_char_tokens;
 
     StringView m_source;
     size_t m_line_number { 1 };
diff --git a/Userland/Libraries/LibSQL/AST/Parser.cpp b/Userland/Libraries/LibSQL/AST/Parser.cpp
index 5bcba3137ff..38d2298e72c 100644
--- a/Userland/Libraries/LibSQL/AST/Parser.cpp
+++ b/Userland/Libraries/LibSQL/AST/Parser.cpp
@@ -91,7 +91,7 @@ NonnullRefPtr<CreateSchema> Parser::parse_create_schema_statement()
         is_error_if_exists = false;
     }
 
-    DeprecatedString schema_name = consume(TokenType::Identifier).value();
+    ByteString schema_name = consume(TokenType::Identifier).value();
     return create_ast_node<CreateSchema>(move(schema_name), is_error_if_exists);
 }
 
@@ -112,8 +112,8 @@ NonnullRefPtr<CreateTable> Parser::parse_create_table_statement()
         is_error_if_table_exists = false;
     }
 
-    DeprecatedString schema_name;
-    DeprecatedString table_name;
+    ByteString schema_name;
+    ByteString table_name;
     parse_schema_and_table_name(schema_name, table_name);
 
     if (consume_if(TokenType::As)) {
@@ -135,8 +135,8 @@ NonnullRefPtr<AlterTable> Parser::parse_alter_table_statement()
     consume(TokenType::Alter);
     consume(TokenType::Table);
 
-    DeprecatedString schema_name;
-    DeprecatedString table_name;
+    ByteString schema_name;
+    ByteString table_name;
     parse_schema_and_table_name(schema_name, table_name);
 
     if (consume_if(TokenType::Add)) {
@@ -177,8 +177,8 @@ NonnullRefPtr<DropTable> Parser::parse_drop_table_statement()
         is_error_if_table_does_not_exist = false;
     }
 
-    DeprecatedString schema_name;
-    DeprecatedString table_name;
+    ByteString schema_name;
+    ByteString table_name;
     parse_schema_and_table_name(schema_name, table_name);
 
     return create_ast_node<DropTable>(move(schema_name), move(table_name), is_error_if_table_does_not_exist);
@@ -201,15 +201,15 @@ NonnullRefPtr<Insert> Parser::parse_insert_statement(RefPtr<CommonTableExpressio
     auto conflict_resolution = parse_conflict_resolution();
     consume(TokenType::Into);
 
-    DeprecatedString schema_name;
-    DeprecatedString table_name;
+    ByteString schema_name;
+    ByteString table_name;
     parse_schema_and_table_name(schema_name, table_name);
 
-    DeprecatedString alias;
+    ByteString alias;
     if (consume_if(TokenType::As))
         alias = consume(TokenType::Identifier).value();
 
-    Vector<DeprecatedString> column_names;
+    Vector<ByteString> column_names;
     if (match(TokenType::ParenOpen))
         parse_comma_separated_list(true, [&]() { column_names.append(consume(TokenType::Identifier).value()); });
 
@@ -260,7 +260,7 @@ NonnullRefPtr<Update> Parser::parse_update_statement(RefPtr<CommonTableExpressio
 
     Vector<Update::UpdateColumns> update_columns;
     parse_comma_separated_list(false, [&]() {
-        Vector<DeprecatedString> column_names;
+        Vector<ByteString> column_names;
         if (match(TokenType::ParenOpen)) {
             parse_comma_separated_list(true, [&]() { column_names.append(consume(TokenType::Identifier).value()); });
         } else {
@@ -391,7 +391,7 @@ RefPtr<CommonTableExpressionList> Parser::parse_common_table_expression_list()
 NonnullRefPtr<Expression> Parser::parse_expression()
 {
     if (++m_parser_state.m_current_expression_depth > Limits::maximum_expression_tree_depth) {
-        syntax_error(DeprecatedString::formatted("Exceeded maximum expression tree depth of {}", Limits::maximum_expression_tree_depth));
+        syntax_error(ByteString::formatted("Exceeded maximum expression tree depth of {}", Limits::maximum_expression_tree_depth));
         return create_ast_node<ErrorExpression>();
     }
 
@@ -558,7 +558,7 @@ RefPtr<Expression> Parser::parse_bind_parameter_expression()
     if (consume_if(TokenType::Placeholder)) {
         auto parameter = m_parser_state.m_bound_parameters;
         if (++m_parser_state.m_bound_parameters > Limits::maximum_bound_parameters)
-            syntax_error(DeprecatedString::formatted("Exceeded maximum number of bound parameters {}", Limits::maximum_bound_parameters));
+            syntax_error(ByteString::formatted("Exceeded maximum number of bound parameters {}", Limits::maximum_bound_parameters));
 
         return create_ast_node<Placeholder>(parameter);
     }
@@ -566,23 +566,23 @@ RefPtr<Expression> Parser::parse_bind_parameter_expression()
     return {};
 }
 
-RefPtr<Expression> Parser::parse_column_name_expression(Optional<DeprecatedString> with_parsed_identifier, bool with_parsed_period)
+RefPtr<Expression> Parser::parse_column_name_expression(Optional<ByteString> with_parsed_identifier, bool with_parsed_period)
 {
     if (!with_parsed_identifier.has_value() && !match(TokenType::Identifier))
         return {};
 
-    DeprecatedString first_identifier;
+    ByteString first_identifier;
     if (!with_parsed_identifier.has_value())
         first_identifier = consume(TokenType::Identifier).value();
     else
         first_identifier = with_parsed_identifier.release_value();
 
-    DeprecatedString schema_name;
-    DeprecatedString table_name;
-    DeprecatedString column_name;
+    ByteString schema_name;
+    ByteString table_name;
+    ByteString column_name;
 
     if (with_parsed_period || consume_if(TokenType::Period)) {
-        DeprecatedString second_identifier = consume(TokenType::Identifier).value();
+        ByteString second_identifier = consume(TokenType::Identifier).value();
 
         if (consume_if(TokenType::Period)) {
             schema_name = move(first_identifier);
@@ -762,7 +762,7 @@ RefPtr<Expression> Parser::parse_collate_expression(NonnullRefPtr<Expression> ex
         return {};
 
     consume();
-    DeprecatedString collation_name = consume(TokenType::Identifier).value();
+    ByteString collation_name = consume(TokenType::Identifier).value();
 
     return create_ast_node<CollateExpression>(move(expression), move(collation_name));
 }
@@ -879,8 +879,8 @@ RefPtr<Expression> Parser::parse_in_expression(NonnullRefPtr<Expression> express
         return create_ast_node<InChainedExpression>(move(expression), move(chain), invert_expression);
     }
 
-    DeprecatedString schema_name;
-    DeprecatedString table_name;
+    ByteString schema_name;
+    ByteString table_name;
     parse_schema_and_table_name(schema_name, table_name);
 
     if (match(TokenType::ParenOpen)) {
@@ -948,7 +948,7 @@ NonnullRefPtr<CommonTableExpression> Parser::parse_common_table_expression()
     // https://sqlite.org/syntax/common-table-expression.html
     auto table_name = consume(TokenType::Identifier).value();
 
-    Vector<DeprecatedString> column_names;
+    Vector<ByteString> column_names;
     if (match(TokenType::ParenOpen))
         parse_comma_separated_list(true, [&]() { column_names.append(consume(TokenType::Identifier).value()); });
 
@@ -963,11 +963,11 @@ NonnullRefPtr<CommonTableExpression> Parser::parse_common_table_expression()
 NonnullRefPtr<QualifiedTableName> Parser::parse_qualified_table_name()
 {
     // https://sqlite.org/syntax/qualified-table-name.html
-    DeprecatedString schema_name;
-    DeprecatedString table_name;
+    ByteString schema_name;
+    ByteString table_name;
     parse_schema_and_table_name(schema_name, table_name);
 
-    DeprecatedString alias;
+    ByteString alias;
     if (consume_if(TokenType::As))
         alias = consume(TokenType::Identifier).value();
 
@@ -991,7 +991,7 @@ NonnullRefPtr<ReturningClause> Parser::parse_returning_clause()
     parse_comma_separated_list(false, [&]() {
         auto expression = parse_expression();
 
-        DeprecatedString column_alias;
+        ByteString column_alias;
         if (consume_if(TokenType::As) || match(TokenType::Identifier))
             column_alias = consume(TokenType::Identifier).value();
 
@@ -1010,7 +1010,7 @@ NonnullRefPtr<ResultColumn> Parser::parse_result_column()
     // If we match an identifier now, we don't know whether it is a table-name of the form "table-name.*", or if it is the start of a
     // column-name-expression, until we try to parse the asterisk. So if we consume an identifier and a period, but don't find an
     // asterisk, hold onto that information to form a column-name-expression later.
-    Optional<DeprecatedString> table_name;
+    Optional<ByteString> table_name;
     bool parsed_period = false;
 
     if (match(TokenType::Identifier)) {
@@ -1024,7 +1024,7 @@ NonnullRefPtr<ResultColumn> Parser::parse_result_column()
         ? parse_expression()
         : static_cast<NonnullRefPtr<Expression>>(*parse_column_name_expression(move(table_name), parsed_period));
 
-    DeprecatedString column_alias;
+    ByteString column_alias;
     if (consume_if(TokenType::As) || match(TokenType::Identifier))
         column_alias = consume(TokenType::Identifier).value();
 
@@ -1034,17 +1034,17 @@ NonnullRefPtr<ResultColumn> Parser::parse_result_column()
 NonnullRefPtr<TableOrSubquery> Parser::parse_table_or_subquery()
 {
     if (++m_parser_state.m_current_subquery_depth > Limits::maximum_subquery_depth)
-        syntax_error(DeprecatedString::formatted("Exceeded maximum subquery depth of {}", Limits::maximum_subquery_depth));
+        syntax_error(ByteString::formatted("Exceeded maximum subquery depth of {}", Limits::maximum_subquery_depth));
 
     ScopeGuard guard([&]() { --m_parser_state.m_current_subquery_depth; });
 
     // https://sqlite.org/syntax/table-or-subquery.html
     if (match(TokenType::Identifier)) {
-        DeprecatedString schema_name;
-        DeprecatedString table_name;
+        ByteString schema_name;
+        ByteString table_name;
         parse_schema_and_table_name(schema_name, table_name);
 
-        DeprecatedString table_alias;
+        ByteString table_alias;
         if (consume_if(TokenType::As) || match(TokenType::Identifier))
             table_alias = consume(TokenType::Identifier).value();
 
@@ -1064,7 +1064,7 @@ NonnullRefPtr<OrderingTerm> Parser::parse_ordering_term()
     // https://sqlite.org/syntax/ordering-term.html
     auto expression = parse_expression();
 
-    DeprecatedString collation_name;
+    ByteString collation_name;
     if (is<CollateExpression>(*expression)) {
         auto const& collate = static_cast<CollateExpression const&>(*expression);
         collation_name = collate.collation_name();
@@ -1089,9 +1089,9 @@ NonnullRefPtr<OrderingTerm> Parser::parse_ordering_term()
     return create_ast_node<OrderingTerm>(move(expression), move(collation_name), order, nulls);
 }
 
-void Parser::parse_schema_and_table_name(DeprecatedString& schema_name, DeprecatedString& table_name)
+void Parser::parse_schema_and_table_name(ByteString& schema_name, ByteString& table_name)
 {
-    DeprecatedString schema_or_table_name = consume(TokenType::Identifier).value();
+    ByteString schema_or_table_name = consume(TokenType::Identifier).value();
 
     if (consume_if(TokenType::Period)) {
         schema_name = move(schema_or_table_name);
@@ -1153,10 +1153,10 @@ bool Parser::match(TokenType type) const
 
 void Parser::expected(StringView what)
 {
-    syntax_error(DeprecatedString::formatted("Unexpected token {}, expected {}", m_parser_state.m_token.name(), what));
+    syntax_error(ByteString::formatted("Unexpected token {}, expected {}", m_parser_state.m_token.name(), what));
 }
 
-void Parser::syntax_error(DeprecatedString message)
+void Parser::syntax_error(ByteString message)
 {
     m_parser_state.m_errors.append({ move(message), position() });
 }
diff --git a/Userland/Libraries/LibSQL/AST/Parser.h b/Userland/Libraries/LibSQL/AST/Parser.h
index 3fbadf47253..2ec59354897 100644
--- a/Userland/Libraries/LibSQL/AST/Parser.h
+++ b/Userland/Libraries/LibSQL/AST/Parser.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringView.h>
 #include <LibSQL/AST/AST.h>
 #include <LibSQL/AST/Lexer.h>
@@ -24,12 +24,12 @@ constexpr size_t maximum_bound_parameters = 1000;
 
 class Parser {
     struct Error {
-        DeprecatedString message;
+        ByteString message;
         SourcePosition position;
 
-        DeprecatedString to_deprecated_string() const
+        ByteString to_byte_string() const
         {
-            return DeprecatedString::formatted("{} (line: {}, column: {})", message, position.line, position.column);
+            return ByteString::formatted("{} (line: {}, column: {})", message, position.line, position.column);
         }
     };
 
@@ -74,7 +74,7 @@ private:
     bool match_secondary_expression() const;
     RefPtr<Expression> parse_literal_value_expression();
     RefPtr<Expression> parse_bind_parameter_expression();
-    RefPtr<Expression> parse_column_name_expression(Optional<DeprecatedString> with_parsed_identifier = {}, bool with_parsed_period = false);
+    RefPtr<Expression> parse_column_name_expression(Optional<ByteString> with_parsed_identifier = {}, bool with_parsed_period = false);
     RefPtr<Expression> parse_unary_operator_expression();
     RefPtr<Expression> parse_binary_operator_expression(NonnullRefPtr<Expression> lhs);
     RefPtr<Expression> parse_chained_expression(bool surrounded_by_parentheses = true);
@@ -97,7 +97,7 @@ private:
     NonnullRefPtr<ResultColumn> parse_result_column();
     NonnullRefPtr<TableOrSubquery> parse_table_or_subquery();
     NonnullRefPtr<OrderingTerm> parse_ordering_term();
-    void parse_schema_and_table_name(DeprecatedString& schema_name, DeprecatedString& table_name);
+    void parse_schema_and_table_name(ByteString& schema_name, ByteString& table_name);
     ConflictResolution parse_conflict_resolution();
 
     template<typename ParseCallback>
@@ -125,7 +125,7 @@ private:
     bool match(TokenType type) const;
 
     void expected(StringView what);
-    void syntax_error(DeprecatedString message);
+    void syntax_error(ByteString message);
 
     SourcePosition position() const;
 
diff --git a/Userland/Libraries/LibSQL/AST/Select.cpp b/Userland/Libraries/LibSQL/AST/Select.cpp
index 96806ff837c..b2d690842f7 100644
--- a/Userland/Libraries/LibSQL/AST/Select.cpp
+++ b/Userland/Libraries/LibSQL/AST/Select.cpp
@@ -12,10 +12,10 @@
 
 namespace SQL::AST {
 
-static DeprecatedString result_column_name(ResultColumn const& column, size_t column_index)
+static ByteString result_column_name(ResultColumn const& column, size_t column_index)
 {
     auto fallback_column_name = [column_index]() {
-        return DeprecatedString::formatted("Column{}", column_index);
+        return ByteString::formatted("Column{}", column_index);
     };
 
     if (auto const& alias = column.column_alias(); !alias.is_empty())
@@ -40,7 +40,7 @@ static DeprecatedString result_column_name(ResultColumn const& column, size_t co
 ResultOr<ResultSet> Select::execute(ExecutionContext& context) const
 {
     Vector<NonnullRefPtr<ResultColumn const>> columns;
-    Vector<DeprecatedString> column_names;
+    Vector<ByteString> column_names;
 
     auto const& result_column_list = this->result_column_list();
     VERIFY(!result_column_list.is_empty());
diff --git a/Userland/Libraries/LibSQL/AST/Token.cpp b/Userland/Libraries/LibSQL/AST/Token.cpp
index dcc394824c5..baf2a5f7358 100644
--- a/Userland/Libraries/LibSQL/AST/Token.cpp
+++ b/Userland/Libraries/LibSQL/AST/Token.cpp
@@ -6,7 +6,7 @@
 
 #include "Token.h"
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <stdlib.h>
 
 namespace SQL::AST {
@@ -40,7 +40,7 @@ TokenCategory Token::category(TokenType type)
 double Token::double_value() const
 {
     VERIFY(type() == TokenType::NumericLiteral);
-    DeprecatedString value(m_value);
+    ByteString value(m_value);
 
     if (value[0] == '0' && value.length() >= 2) {
         if (value[1] == 'x' || value[1] == 'X')
diff --git a/Userland/Libraries/LibSQL/AST/Token.h b/Userland/Libraries/LibSQL/AST/Token.h
index 59b889ab0a8..aec43bead1a 100644
--- a/Userland/Libraries/LibSQL/AST/Token.h
+++ b/Userland/Libraries/LibSQL/AST/Token.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/StringView.h>
 
@@ -224,7 +224,7 @@ struct SourcePosition {
 
 class Token {
 public:
-    Token(TokenType type, DeprecatedString value, SourcePosition start_position, SourcePosition end_position)
+    Token(TokenType type, ByteString value, SourcePosition start_position, SourcePosition end_position)
         : m_type(type)
         , m_value(move(value))
         , m_start_position(start_position)
@@ -239,7 +239,7 @@ public:
     TokenType type() const { return m_type; }
     TokenCategory category() const { return category(m_type); }
 
-    DeprecatedString const& value() const { return m_value; }
+    ByteString const& value() const { return m_value; }
     double double_value() const;
 
     SourcePosition const& start_position() const { return m_start_position; }
@@ -247,7 +247,7 @@ public:
 
 private:
     TokenType m_type;
-    DeprecatedString m_value;
+    ByteString m_value;
     SourcePosition m_start_position;
     SourcePosition m_end_position;
 };
diff --git a/Userland/Libraries/LibSQL/BTree.h b/Userland/Libraries/LibSQL/BTree.h
index 4dc1fd1f050..7d0798232a5 100644
--- a/Userland/Libraries/LibSQL/BTree.h
+++ b/Userland/Libraries/LibSQL/BTree.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/Optional.h>
@@ -75,7 +75,7 @@ public:
 
 private:
     TreeNode(BTree&, TreeNode*, DownPointer&, u32 = 0);
-    void dump_if(int, DeprecatedString&& = "");
+    void dump_if(int, ByteString&& = "");
     bool insert_in_leaf(Key const&);
     void just_insert(Key const&, TreeNode* = nullptr);
     void split();
diff --git a/Userland/Libraries/LibSQL/Database.cpp b/Userland/Libraries/LibSQL/Database.cpp
index d567f3918cb..3c3fa16091b 100644
--- a/Userland/Libraries/LibSQL/Database.cpp
+++ b/Userland/Libraries/LibSQL/Database.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibSQL/BTree.h>
 #include <LibSQL/Database.h>
 #include <LibSQL/Heap.h>
@@ -15,7 +15,7 @@
 
 namespace SQL {
 
-ErrorOr<NonnullRefPtr<Database>> Database::create(DeprecatedString name)
+ErrorOr<NonnullRefPtr<Database>> Database::create(ByteString name)
 {
     auto heap = TRY(Heap::create(move(name)));
     return adopt_nonnull_ref_or_enomem(new (nothrow) Database(move(heap)));
@@ -96,14 +96,14 @@ ResultOr<void> Database::add_schema(SchemaDef const& schema)
     return {};
 }
 
-Key Database::get_schema_key(DeprecatedString const& schema_name)
+Key Database::get_schema_key(ByteString const& schema_name)
 {
     auto key = SchemaDef::make_key();
     key["schema_name"] = schema_name;
     return key;
 }
 
-ResultOr<NonnullRefPtr<SchemaDef>> Database::get_schema(DeprecatedString const& schema)
+ResultOr<NonnullRefPtr<SchemaDef>> Database::get_schema(ByteString const& schema)
 {
     VERIFY(is_open());
 
@@ -139,14 +139,14 @@ ResultOr<void> Database::add_table(TableDef& table)
     return {};
 }
 
-Key Database::get_table_key(DeprecatedString const& schema_name, DeprecatedString const& table_name)
+Key Database::get_table_key(ByteString const& schema_name, ByteString const& table_name)
 {
     auto key = TableDef::make_key(get_schema_key(schema_name));
     key["table_name"] = table_name;
     return key;
 }
 
-ResultOr<NonnullRefPtr<TableDef>> Database::get_table(DeprecatedString const& schema, DeprecatedString const& name)
+ResultOr<NonnullRefPtr<TableDef>> Database::get_table(ByteString const& schema, ByteString const& name)
 {
     VERIFY(is_open());
 
@@ -160,7 +160,7 @@ ResultOr<NonnullRefPtr<TableDef>> Database::get_table(DeprecatedString const& sc
 
     auto table_iterator = m_tables->find(key);
     if (table_iterator.is_end() || (*table_iterator != key))
-        return Result { SQLCommand::Unknown, SQLErrorCode::TableDoesNotExist, DeprecatedString::formatted("{}.{}", schema_name, name) };
+        return Result { SQLCommand::Unknown, SQLErrorCode::TableDoesNotExist, ByteString::formatted("{}.{}", schema_name, name) };
 
     auto schema_def = TRY(get_schema(schema));
     auto table_def = TRY(TableDef::create(schema_def, name));
diff --git a/Userland/Libraries/LibSQL/Database.h b/Userland/Libraries/LibSQL/Database.h
index bef605414e4..863e2327f8e 100644
--- a/Userland/Libraries/LibSQL/Database.h
+++ b/Userland/Libraries/LibSQL/Database.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefPtr.h>
 #include <LibSQL/Forward.h>
@@ -25,7 +25,7 @@ namespace SQL {
  */
 class Database : public RefCounted<Database> {
 public:
-    static ErrorOr<NonnullRefPtr<Database>> create(DeprecatedString);
+    static ErrorOr<NonnullRefPtr<Database>> create(ByteString);
     ~Database();
 
     ResultOr<void> open();
@@ -34,12 +34,12 @@ public:
     ErrorOr<size_t> file_size_in_bytes() const { return m_heap->file_size_in_bytes(); }
 
     ResultOr<void> add_schema(SchemaDef const&);
-    static Key get_schema_key(DeprecatedString const&);
-    ResultOr<NonnullRefPtr<SchemaDef>> get_schema(DeprecatedString const&);
+    static Key get_schema_key(ByteString const&);
+    ResultOr<NonnullRefPtr<SchemaDef>> get_schema(ByteString const&);
 
     ResultOr<void> add_table(TableDef& table);
-    static Key get_table_key(DeprecatedString const&, DeprecatedString const&);
-    ResultOr<NonnullRefPtr<TableDef>> get_table(DeprecatedString const&, DeprecatedString const&);
+    static Key get_table_key(ByteString const&, ByteString const&);
+    ResultOr<NonnullRefPtr<TableDef>> get_table(ByteString const&, ByteString const&);
 
     ErrorOr<Vector<Row>> select_all(TableDef&);
     ErrorOr<Vector<Row>> match(TableDef&, Key const&);
diff --git a/Userland/Libraries/LibSQL/Heap.cpp b/Userland/Libraries/LibSQL/Heap.cpp
index f2d419d8840..6796b75b866 100644
--- a/Userland/Libraries/LibSQL/Heap.cpp
+++ b/Userland/Libraries/LibSQL/Heap.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/QuickSort.h>
 #include <LibCore/System.h>
@@ -14,12 +14,12 @@
 
 namespace SQL {
 
-ErrorOr<NonnullRefPtr<Heap>> Heap::create(DeprecatedString file_name)
+ErrorOr<NonnullRefPtr<Heap>> Heap::create(ByteString file_name)
 {
     return adopt_nonnull_ref_or_enomem(new (nothrow) Heap(move(file_name)));
 }
 
-Heap::Heap(DeprecatedString file_name)
+Heap::Heap(ByteString file_name)
     : m_name(move(file_name))
 {
 }
diff --git a/Userland/Libraries/LibSQL/Heap.h b/Userland/Libraries/LibSQL/Heap.h
index 8178a2c6a8d..b3fe5f30189 100644
--- a/Userland/Libraries/LibSQL/Heap.h
+++ b/Userland/Libraries/LibSQL/Heap.h
@@ -8,8 +8,8 @@
 #pragma once
 
 #include <AK/Array.h>
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/HashMap.h>
 #include <AK/RefCounted.h>
 #include <AK/Vector.h>
@@ -68,10 +68,10 @@ class Heap : public RefCounted<Heap> {
 public:
     static constexpr u32 VERSION = 4;
 
-    static ErrorOr<NonnullRefPtr<Heap>> create(DeprecatedString);
+    static ErrorOr<NonnullRefPtr<Heap>> create(ByteString);
     virtual ~Heap();
 
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
 
     ErrorOr<void> open();
     ErrorOr<size_t> file_size_in_bytes() const;
@@ -122,7 +122,7 @@ public:
     ErrorOr<void> flush();
 
 private:
-    explicit Heap(DeprecatedString);
+    explicit Heap(ByteString);
 
     ErrorOr<ByteBuffer> read_raw_block(Block::Index);
     ErrorOr<void> write_raw_block(Block::Index, ReadonlyBytes);
@@ -136,7 +136,7 @@ private:
     ErrorOr<void> initialize_zero_block();
     ErrorOr<void> update_zero_block();
 
-    DeprecatedString m_name;
+    ByteString m_name;
 
     OwnPtr<Core::InputBufferedFile> m_file;
     Block::Index m_highest_block_written { 0 };
diff --git a/Userland/Libraries/LibSQL/Meta.cpp b/Userland/Libraries/LibSQL/Meta.cpp
index 0fa07706936..caeae9d2bac 100644
--- a/Userland/Libraries/LibSQL/Meta.cpp
+++ b/Userland/Libraries/LibSQL/Meta.cpp
@@ -15,17 +15,17 @@ u32 Relation::hash() const
     return key().hash();
 }
 
-ErrorOr<NonnullRefPtr<SchemaDef>> SchemaDef::create(DeprecatedString name)
+ErrorOr<NonnullRefPtr<SchemaDef>> SchemaDef::create(ByteString name)
 {
     return adopt_nonnull_ref_or_enomem(new (nothrow) SchemaDef(move(name)));
 }
 
 ErrorOr<NonnullRefPtr<SchemaDef>> SchemaDef::create(Key const& key)
 {
-    return create(key["schema_name"].to_deprecated_string());
+    return create(key["schema_name"].to_byte_string());
 }
 
-SchemaDef::SchemaDef(DeprecatedString name)
+SchemaDef::SchemaDef(ByteString name)
     : Relation(move(name))
 {
 }
@@ -52,12 +52,12 @@ NonnullRefPtr<IndexDef> SchemaDef::index_def()
     return s_index_def;
 }
 
-ErrorOr<NonnullRefPtr<ColumnDef>> ColumnDef::create(Relation* parent, size_t column_number, DeprecatedString name, SQLType sql_type)
+ErrorOr<NonnullRefPtr<ColumnDef>> ColumnDef::create(Relation* parent, size_t column_number, ByteString name, SQLType sql_type)
 {
     return adopt_nonnull_ref_or_enomem(new (nothrow) ColumnDef(parent, column_number, move(name), sql_type));
 }
 
-ColumnDef::ColumnDef(Relation* parent, size_t column_number, DeprecatedString name, SQLType sql_type)
+ColumnDef::ColumnDef(Relation* parent, size_t column_number, ByteString name, SQLType sql_type)
     : Relation(move(name), parent)
     , m_index(column_number)
     , m_type(sql_type)
@@ -100,35 +100,35 @@ NonnullRefPtr<IndexDef> ColumnDef::index_def()
     return s_index_def;
 }
 
-ErrorOr<NonnullRefPtr<KeyPartDef>> KeyPartDef::create(IndexDef* index, DeprecatedString name, SQLType sql_type, Order sort_order)
+ErrorOr<NonnullRefPtr<KeyPartDef>> KeyPartDef::create(IndexDef* index, ByteString name, SQLType sql_type, Order sort_order)
 {
     return adopt_nonnull_ref_or_enomem(new (nothrow) KeyPartDef(index, move(name), sql_type, sort_order));
 }
 
-KeyPartDef::KeyPartDef(IndexDef* index, DeprecatedString name, SQLType sql_type, Order sort_order)
+KeyPartDef::KeyPartDef(IndexDef* index, ByteString name, SQLType sql_type, Order sort_order)
     : ColumnDef(index, index->size(), move(name), sql_type)
     , m_sort_order(sort_order)
 {
 }
 
-ErrorOr<NonnullRefPtr<IndexDef>> IndexDef::create(TableDef* table, DeprecatedString name, bool unique, u32 pointer)
+ErrorOr<NonnullRefPtr<IndexDef>> IndexDef::create(TableDef* table, ByteString name, bool unique, u32 pointer)
 {
     return adopt_nonnull_ref_or_enomem(new (nothrow) IndexDef(table, move(name), unique, pointer));
 }
 
-ErrorOr<NonnullRefPtr<IndexDef>> IndexDef::create(DeprecatedString name, bool unique, u32 pointer)
+ErrorOr<NonnullRefPtr<IndexDef>> IndexDef::create(ByteString name, bool unique, u32 pointer)
 {
     return create(nullptr, move(name), unique, pointer);
 }
 
-IndexDef::IndexDef(TableDef* table, DeprecatedString name, bool unique, u32 pointer)
+IndexDef::IndexDef(TableDef* table, ByteString name, bool unique, u32 pointer)
     : Relation(move(name), pointer, table)
     , m_key_definition()
     , m_unique(unique)
 {
 }
 
-void IndexDef::append_column(DeprecatedString name, SQLType sql_type, Order sort_order)
+void IndexDef::append_column(ByteString name, SQLType sql_type, Order sort_order)
 {
     auto part = KeyPartDef::create(this, move(name), sql_type, sort_order).release_value_but_fixme_should_propagate_errors();
     m_key_definition.append(part);
@@ -170,12 +170,12 @@ NonnullRefPtr<IndexDef> IndexDef::index_def()
     return s_index_def;
 }
 
-ErrorOr<NonnullRefPtr<TableDef>> TableDef::create(SchemaDef* schema, DeprecatedString name)
+ErrorOr<NonnullRefPtr<TableDef>> TableDef::create(SchemaDef* schema, ByteString name)
 {
     return adopt_nonnull_ref_or_enomem(new (nothrow) TableDef(schema, move(name)));
 }
 
-TableDef::TableDef(SchemaDef* schema, DeprecatedString name)
+TableDef::TableDef(SchemaDef* schema, ByteString name)
     : Relation(move(name), schema)
     , m_columns()
     , m_indexes()
@@ -200,7 +200,7 @@ Key TableDef::key() const
     return key;
 }
 
-void TableDef::append_column(DeprecatedString name, SQLType sql_type)
+void TableDef::append_column(ByteString name, SQLType sql_type)
 {
     auto column = ColumnDef::create(this, num_columns(), move(name), sql_type).release_value_but_fixme_should_propagate_errors();
     m_columns.append(column);
@@ -211,7 +211,7 @@ void TableDef::append_column(Key const& column)
     auto column_type = column["column_type"].to_int<UnderlyingType<SQLType>>();
     VERIFY(column_type.has_value());
 
-    append_column(column["column_name"].to_deprecated_string(), static_cast<SQLType>(*column_type));
+    append_column(column["column_name"].to_byte_string(), static_cast<SQLType>(*column_type));
 }
 
 Key TableDef::make_key(SchemaDef const& schema_def)
diff --git a/Userland/Libraries/LibSQL/Meta.h b/Userland/Libraries/LibSQL/Meta.h
index 7a51ebb475c..997752680d3 100644
--- a/Userland/Libraries/LibSQL/Meta.h
+++ b/Userland/Libraries/LibSQL/Meta.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefCounted.h>
 #include <AK/Result.h>
@@ -28,7 +28,7 @@ class Relation : public RefCounted<Relation> {
 public:
     virtual ~Relation() = default;
 
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
     Relation const* parent() const { return m_parent; }
 
     u32 hash() const;
@@ -37,27 +37,27 @@ public:
     virtual Key key() const = 0;
 
 protected:
-    Relation(DeprecatedString name, Block::Index block_index, Relation* parent = nullptr)
+    Relation(ByteString name, Block::Index block_index, Relation* parent = nullptr)
         : m_name(move(name))
         , m_block_index(block_index)
         , m_parent(parent)
     {
     }
 
-    explicit Relation(DeprecatedString name, Relation* parent = nullptr)
+    explicit Relation(ByteString name, Relation* parent = nullptr)
         : Relation(move(name), 0, parent)
     {
     }
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
     Block::Index m_block_index { 0 };
     Relation const* m_parent { nullptr };
 };
 
 class SchemaDef : public Relation {
 public:
-    static ErrorOr<NonnullRefPtr<SchemaDef>> create(DeprecatedString name);
+    static ErrorOr<NonnullRefPtr<SchemaDef>> create(ByteString name);
     static ErrorOr<NonnullRefPtr<SchemaDef>> create(Key const&);
 
     Key key() const override;
@@ -65,12 +65,12 @@ public:
     static Key make_key();
 
 private:
-    explicit SchemaDef(DeprecatedString);
+    explicit SchemaDef(ByteString);
 };
 
 class ColumnDef : public Relation {
 public:
-    static ErrorOr<NonnullRefPtr<ColumnDef>> create(Relation*, size_t, DeprecatedString, SQLType);
+    static ErrorOr<NonnullRefPtr<ColumnDef>> create(Relation*, size_t, ByteString, SQLType);
 
     Key key() const override;
     SQLType type() const { return m_type; }
@@ -84,7 +84,7 @@ public:
     static Key make_key(TableDef const&);
 
 protected:
-    ColumnDef(Relation*, size_t, DeprecatedString, SQLType);
+    ColumnDef(Relation*, size_t, ByteString, SQLType);
 
 private:
     size_t m_index;
@@ -95,32 +95,32 @@ private:
 
 class KeyPartDef : public ColumnDef {
 public:
-    static ErrorOr<NonnullRefPtr<KeyPartDef>> create(IndexDef*, DeprecatedString, SQLType, Order = Order::Ascending);
+    static ErrorOr<NonnullRefPtr<KeyPartDef>> create(IndexDef*, ByteString, SQLType, Order = Order::Ascending);
 
     Order sort_order() const { return m_sort_order; }
 
 private:
-    KeyPartDef(IndexDef*, DeprecatedString, SQLType, Order);
+    KeyPartDef(IndexDef*, ByteString, SQLType, Order);
 
     Order m_sort_order { Order::Ascending };
 };
 
 class IndexDef : public Relation {
 public:
-    static ErrorOr<NonnullRefPtr<IndexDef>> create(TableDef*, DeprecatedString, bool unique = true, u32 pointer = 0);
-    static ErrorOr<NonnullRefPtr<IndexDef>> create(DeprecatedString, bool unique = true, u32 pointer = 0);
+    static ErrorOr<NonnullRefPtr<IndexDef>> create(TableDef*, ByteString, bool unique = true, u32 pointer = 0);
+    static ErrorOr<NonnullRefPtr<IndexDef>> create(ByteString, bool unique = true, u32 pointer = 0);
 
     Vector<NonnullRefPtr<KeyPartDef>> const& key_definition() const { return m_key_definition; }
     bool unique() const { return m_unique; }
     [[nodiscard]] size_t size() const { return m_key_definition.size(); }
-    void append_column(DeprecatedString, SQLType, Order = Order::Ascending);
+    void append_column(ByteString, SQLType, Order = Order::Ascending);
     Key key() const override;
     [[nodiscard]] NonnullRefPtr<TupleDescriptor> to_tuple_descriptor() const;
     static NonnullRefPtr<IndexDef> index_def();
     static Key make_key(TableDef const& table_def);
 
 private:
-    IndexDef(TableDef*, DeprecatedString, bool unique, u32 pointer);
+    IndexDef(TableDef*, ByteString, bool unique, u32 pointer);
 
     Vector<NonnullRefPtr<KeyPartDef>> m_key_definition;
     bool m_unique { false };
@@ -130,10 +130,10 @@ private:
 
 class TableDef : public Relation {
 public:
-    static ErrorOr<NonnullRefPtr<TableDef>> create(SchemaDef*, DeprecatedString);
+    static ErrorOr<NonnullRefPtr<TableDef>> create(SchemaDef*, ByteString);
 
     Key key() const override;
-    void append_column(DeprecatedString, SQLType);
+    void append_column(ByteString, SQLType);
     void append_column(Key const&);
     size_t num_columns() { return m_columns.size(); }
     size_t num_indexes() { return m_indexes.size(); }
@@ -146,7 +146,7 @@ public:
     static Key make_key(Key const& schema_key);
 
 private:
-    explicit TableDef(SchemaDef*, DeprecatedString);
+    explicit TableDef(SchemaDef*, ByteString);
 
     Vector<NonnullRefPtr<ColumnDef>> m_columns;
     Vector<NonnullRefPtr<IndexDef>> m_indexes;
diff --git a/Userland/Libraries/LibSQL/Result.cpp b/Userland/Libraries/LibSQL/Result.cpp
index 2a902da8690..b809e12a458 100644
--- a/Userland/Libraries/LibSQL/Result.cpp
+++ b/Userland/Libraries/LibSQL/Result.cpp
@@ -9,7 +9,7 @@
 
 namespace SQL {
 
-DeprecatedString Result::error_string() const
+ByteString Result::error_string() const
 {
     VERIFY(is_error());
 
@@ -41,7 +41,7 @@ DeprecatedString Result::error_string() const
         builder.append(error_description);
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/Userland/Libraries/LibSQL/Result.h b/Userland/Libraries/LibSQL/Result.h
index f6832b78dc2..0aacf2bfbd0 100644
--- a/Userland/Libraries/LibSQL/Result.h
+++ b/Userland/Libraries/LibSQL/Result.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Noncopyable.h>
 #include <LibSQL/Type.h>
@@ -90,7 +90,7 @@ public:
     {
     }
 
-    ALWAYS_INLINE Result(SQLCommand command, SQLErrorCode error, DeprecatedString error_message)
+    ALWAYS_INLINE Result(SQLCommand command, SQLErrorCode error, ByteString error_message)
         : m_command(command)
         , m_error(error)
         , m_error_message(move(error_message))
@@ -105,7 +105,7 @@ public:
 
     SQLCommand command() const { return m_command; }
     SQLErrorCode error() const { return m_error; }
-    DeprecatedString error_string() const;
+    ByteString error_string() const;
 
     // These are for compatibility with the TRY() macro in AK.
     [[nodiscard]] bool is_error() const { return m_error != SQLErrorCode::NoError; }
@@ -123,7 +123,7 @@ private:
     SQLCommand m_command { SQLCommand::Unknown };
 
     SQLErrorCode m_error { SQLErrorCode::NoError };
-    Optional<DeprecatedString> m_error_message {};
+    Optional<ByteString> m_error_message {};
 };
 
 template<typename ValueType>
diff --git a/Userland/Libraries/LibSQL/ResultSet.h b/Userland/Libraries/LibSQL/ResultSet.h
index 765fc52e73b..6c5f8683330 100644
--- a/Userland/Libraries/LibSQL/ResultSet.h
+++ b/Userland/Libraries/LibSQL/ResultSet.h
@@ -25,14 +25,14 @@ public:
     {
     }
 
-    ALWAYS_INLINE ResultSet(SQLCommand command, Vector<DeprecatedString> column_names)
+    ALWAYS_INLINE ResultSet(SQLCommand command, Vector<ByteString> column_names)
         : m_command(command)
         , m_column_names(move(column_names))
     {
     }
 
     SQLCommand command() const { return m_command; }
-    Vector<DeprecatedString> const& column_names() const { return m_column_names; }
+    Vector<ByteString> const& column_names() const { return m_column_names; }
 
     void insert_row(Tuple const& row, Tuple const& sort_key);
     void limit(size_t offset, size_t limit);
@@ -41,7 +41,7 @@ private:
     size_t binary_search(Tuple const& sort_key, size_t low, size_t high);
 
     SQLCommand m_command { SQLCommand::Unknown };
-    Vector<DeprecatedString> m_column_names;
+    Vector<ByteString> m_column_names;
 };
 
 }
diff --git a/Userland/Libraries/LibSQL/SQLClient.cpp b/Userland/Libraries/LibSQL/SQLClient.cpp
index 53479fb1245..6a3bca1d941 100644
--- a/Userland/Libraries/LibSQL/SQLClient.cpp
+++ b/Userland/Libraries/LibSQL/SQLClient.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/String.h>
 #include <LibSQL/SQLClient.h>
 
@@ -23,7 +23,7 @@ namespace SQL {
 #if !defined(AK_OS_SERENITY)
 
 // This is heavily based on how SystemServer's Service creates its socket.
-static ErrorOr<int> create_database_socket(DeprecatedString const& socket_path)
+static ErrorOr<int> create_database_socket(ByteString const& socket_path)
 {
     if (FileSystem::exists(socket_path))
         TRY(Core::System::unlink(socket_path));
@@ -51,7 +51,7 @@ static ErrorOr<int> create_database_socket(DeprecatedString const& socket_path)
     return socket_fd;
 }
 
-static ErrorOr<void> launch_server(DeprecatedString const& socket_path, DeprecatedString const& pid_path, Vector<String> candidate_server_paths)
+static ErrorOr<void> launch_server(ByteString const& socket_path, ByteString const& pid_path, Vector<String> candidate_server_paths)
 {
     auto server_fd_or_error = create_database_socket(socket_path);
     if (server_fd_or_error.is_error()) {
@@ -73,14 +73,14 @@ static ErrorOr<void> launch_server(DeprecatedString const& socket_path, Deprecat
 
         if (server_pid != 0) {
             auto server_pid_file = TRY(Core::File::open(pid_path, Core::File::OpenMode::Write));
-            TRY(server_pid_file->write_until_depleted(DeprecatedString::number(server_pid).bytes()));
+            TRY(server_pid_file->write_until_depleted(ByteString::number(server_pid).bytes()));
 
             TRY(Core::System::kill(getpid(), SIGTERM));
         }
 
         server_fd = TRY(Core::System::dup(server_fd));
 
-        auto takeover_string = DeprecatedString::formatted("SQLServer:{}", server_fd);
+        auto takeover_string = ByteString::formatted("SQLServer:{}", server_fd);
         TRY(Core::System::setenv("SOCKET_TAKEOVER"sv, takeover_string, true));
 
         ErrorOr<void> result;
@@ -110,7 +110,7 @@ static ErrorOr<void> launch_server(DeprecatedString const& socket_path, Deprecat
     return {};
 }
 
-static ErrorOr<bool> should_launch_server(DeprecatedString const& pid_path)
+static ErrorOr<bool> should_launch_server(ByteString const& pid_path)
 {
     if (!FileSystem::exists(pid_path))
         return true;
@@ -149,8 +149,8 @@ static ErrorOr<bool> should_launch_server(DeprecatedString const& pid_path)
 ErrorOr<NonnullRefPtr<SQLClient>> SQLClient::launch_server_and_create_client(Vector<String> candidate_server_paths)
 {
     auto runtime_directory = TRY(Core::StandardPaths::runtime_directory());
-    auto socket_path = DeprecatedString::formatted("{}/SQLServer.socket", runtime_directory);
-    auto pid_path = DeprecatedString::formatted("{}/SQLServer.pid", runtime_directory);
+    auto socket_path = ByteString::formatted("{}/SQLServer.socket", runtime_directory);
+    auto pid_path = ByteString::formatted("{}/SQLServer.pid", runtime_directory);
 
     if (TRY(should_launch_server(pid_path)))
         TRY(launch_server(socket_path, pid_path, move(candidate_server_paths)));
@@ -163,7 +163,7 @@ ErrorOr<NonnullRefPtr<SQLClient>> SQLClient::launch_server_and_create_client(Vec
 
 #endif
 
-void SQLClient::execution_success(u64 statement_id, u64 execution_id, Vector<DeprecatedString> const& column_names, bool has_results, size_t created, size_t updated, size_t deleted)
+void SQLClient::execution_success(u64 statement_id, u64 execution_id, Vector<ByteString> const& column_names, bool has_results, size_t created, size_t updated, size_t deleted)
 {
     if (!on_execution_success) {
         outln("{} row(s) created, {} updated, {} deleted", created, updated, deleted);
@@ -173,7 +173,7 @@ void SQLClient::execution_success(u64 statement_id, u64 execution_id, Vector<Dep
     ExecutionSuccess success {
         .statement_id = statement_id,
         .execution_id = execution_id,
-        .column_names = move(const_cast<Vector<DeprecatedString>&>(column_names)),
+        .column_names = move(const_cast<Vector<ByteString>&>(column_names)),
         .has_results = has_results,
         .rows_created = created,
         .rows_updated = updated,
@@ -183,7 +183,7 @@ void SQLClient::execution_success(u64 statement_id, u64 execution_id, Vector<Dep
     on_execution_success(move(success));
 }
 
-void SQLClient::execution_error(u64 statement_id, u64 execution_id, SQLErrorCode const& code, DeprecatedString const& message)
+void SQLClient::execution_error(u64 statement_id, u64 execution_id, SQLErrorCode const& code, ByteString const& message)
 {
     if (!on_execution_error) {
         warnln("Execution error for statement_id {}: {} ({})", statement_id, message, to_underlying(code));
@@ -194,7 +194,7 @@ void SQLClient::execution_error(u64 statement_id, u64 execution_id, SQLErrorCode
         .statement_id = statement_id,
         .execution_id = execution_id,
         .error_code = code,
-        .error_message = move(const_cast<DeprecatedString&>(message)),
+        .error_message = move(const_cast<ByteString&>(message)),
     };
 
     on_execution_error(move(error));
diff --git a/Userland/Libraries/LibSQL/SQLClient.h b/Userland/Libraries/LibSQL/SQLClient.h
index fb8bda0deb6..ef3b2ca570c 100644
--- a/Userland/Libraries/LibSQL/SQLClient.h
+++ b/Userland/Libraries/LibSQL/SQLClient.h
@@ -19,7 +19,7 @@ struct ExecutionSuccess {
     u64 statement_id { 0 };
     u64 execution_id { 0 };
 
-    Vector<DeprecatedString> column_names;
+    Vector<ByteString> column_names;
     bool has_results { false };
     size_t rows_created { 0 };
     size_t rows_updated { 0 };
@@ -31,7 +31,7 @@ struct ExecutionError {
     u64 execution_id { 0 };
 
     SQLErrorCode error_code;
-    DeprecatedString error_message;
+    ByteString error_message;
 };
 
 struct ExecutionResult {
@@ -71,8 +71,8 @@ private:
     {
     }
 
-    virtual void execution_success(u64 statement_id, u64 execution_id, Vector<DeprecatedString> const& column_names, bool has_results, size_t created, size_t updated, size_t deleted) override;
-    virtual void execution_error(u64 statement_id, u64 execution_id, SQLErrorCode const& code, DeprecatedString const& message) override;
+    virtual void execution_success(u64 statement_id, u64 execution_id, Vector<ByteString> const& column_names, bool has_results, size_t created, size_t updated, size_t deleted) override;
+    virtual void execution_error(u64 statement_id, u64 execution_id, SQLErrorCode const& code, ByteString const& message) override;
     virtual void next_result(u64 statement_id, u64 execution_id, Vector<SQL::Value> const&) override;
     virtual void results_exhausted(u64 statement_id, u64 execution_id, size_t total_rows) override;
 };
diff --git a/Userland/Libraries/LibSQL/Serializer.cpp b/Userland/Libraries/LibSQL/Serializer.cpp
index ae83dc2c466..e9bf24e08cc 100644
--- a/Userland/Libraries/LibSQL/Serializer.cpp
+++ b/Userland/Libraries/LibSQL/Serializer.cpp
@@ -8,18 +8,18 @@
 
 namespace SQL {
 
-void Serializer::serialize(DeprecatedString const& text)
+void Serializer::serialize(ByteString const& text)
 {
     serialize<u32>(text.length());
     if (!text.is_empty())
         write((u8 const*)text.characters(), text.length());
 }
 
-void Serializer::deserialize_to(DeprecatedString& text)
+void Serializer::deserialize_to(ByteString& text)
 {
     auto length = deserialize<u32>();
     if (length > 0) {
-        text = DeprecatedString(reinterpret_cast<char const*>(read(length)), length);
+        text = ByteString(reinterpret_cast<char const*>(read(length)), length);
     } else {
         text = "";
     }
diff --git a/Userland/Libraries/LibSQL/Serializer.h b/Userland/Libraries/LibSQL/Serializer.h
index f64fe97789f..991091f5387 100644
--- a/Userland/Libraries/LibSQL/Serializer.h
+++ b/Userland/Libraries/LibSQL/Serializer.h
@@ -7,8 +7,8 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <LibSQL/Forward.h>
 #include <LibSQL/Heap.h>
@@ -64,7 +64,7 @@ public:
             t.deserialize(*this);
     }
 
-    void deserialize_to(DeprecatedString& text);
+    void deserialize_to(ByteString& text);
 
     template<typename T, typename... Args>
     NonnullOwnPtr<T> make_and_deserialize(Args&&... args)
@@ -99,7 +99,7 @@ public:
             t.serialize(*this);
     }
 
-    void serialize(DeprecatedString const&);
+    void serialize(ByteString const&);
 
     template<typename T>
     bool serialize_and_write(T const& t)
@@ -145,17 +145,17 @@ private:
         return buffer_ptr;
     }
 
-    static void dump(u8 const* ptr, size_t sz, DeprecatedString const& prefix)
+    static void dump(u8 const* ptr, size_t sz, ByteString const& prefix)
     {
         StringBuilder builder;
         builder.appendff("{0} {1:04x} | ", prefix, sz);
-        Vector<DeprecatedString> bytes;
+        Vector<ByteString> bytes;
         for (auto ix = 0u; ix < sz; ++ix)
-            bytes.append(DeprecatedString::formatted("{0:02x}", *(ptr + ix)));
+            bytes.append(ByteString::formatted("{0:02x}", *(ptr + ix)));
         StringBuilder bytes_builder;
         bytes_builder.join(' ', bytes);
-        builder.append(bytes_builder.to_deprecated_string());
-        dbgln(builder.to_deprecated_string());
+        builder.append(bytes_builder.to_byte_string());
+        dbgln(builder.to_byte_string());
     }
 
     ByteBuffer m_buffer {};
diff --git a/Userland/Libraries/LibSQL/TreeNode.cpp b/Userland/Libraries/LibSQL/TreeNode.cpp
index 7802366ea65..39fc5770039 100644
--- a/Userland/Libraries/LibSQL/TreeNode.cpp
+++ b/Userland/Libraries/LibSQL/TreeNode.cpp
@@ -151,7 +151,7 @@ size_t TreeNode::length() const
 
 bool TreeNode::insert(Key const& key)
 {
-    dbgln_if(SQL_DEBUG, "[#{}] INSERT({})", block_index(), key.to_deprecated_string());
+    dbgln_if(SQL_DEBUG, "[#{}] INSERT({})", block_index(), key.to_byte_string());
     if (!is_leaf())
         return node_for(key)->insert_in_leaf(key);
     return insert_in_leaf(key);
@@ -159,14 +159,14 @@ bool TreeNode::insert(Key const& key)
 
 bool TreeNode::update_key_pointer(Key const& key)
 {
-    dbgln_if(SQL_DEBUG, "[#{}] UPDATE({}, {})", block_index(), key.to_deprecated_string(), key.block_index());
+    dbgln_if(SQL_DEBUG, "[#{}] UPDATE({}, {})", block_index(), key.to_byte_string(), key.block_index());
     if (!is_leaf())
         return node_for(key)->update_key_pointer(key);
 
     for (auto ix = 0u; ix < size(); ix++) {
         if (key == m_entries[ix]) {
             dbgln_if(SQL_DEBUG, "[#{}] {} == {}",
-                block_index(), key.to_deprecated_string(), m_entries[ix].to_deprecated_string());
+                block_index(), key.to_byte_string(), m_entries[ix].to_byte_string());
             if (m_entries[ix].block_index() != key.block_index()) {
                 m_entries[ix].set_block_index(key.block_index());
                 dump_if(SQL_DEBUG, "To WAL");
@@ -184,13 +184,13 @@ bool TreeNode::insert_in_leaf(Key const& key)
     if (!m_tree.duplicates_allowed()) {
         for (auto& entry : m_entries) {
             if (key == entry) {
-                dbgln_if(SQL_DEBUG, "[#{}] duplicate key {}", block_index(), key.to_deprecated_string());
+                dbgln_if(SQL_DEBUG, "[#{}] duplicate key {}", block_index(), key.to_byte_string());
                 return false;
             }
         }
     }
 
-    dbgln_if(SQL_DEBUG, "[#{}] insert_in_leaf({})", block_index(), key.to_deprecated_string());
+    dbgln_if(SQL_DEBUG, "[#{}] insert_in_leaf({})", block_index(), key.to_byte_string());
     just_insert(key, nullptr);
     return true;
 }
@@ -207,56 +207,56 @@ TreeNode* TreeNode::down_node(size_t ix)
 
 TreeNode* TreeNode::node_for(Key const& key)
 {
-    dump_if(SQL_DEBUG, DeprecatedString::formatted("node_for(Key {})", key.to_deprecated_string()));
+    dump_if(SQL_DEBUG, ByteString::formatted("node_for(Key {})", key.to_byte_string()));
     if (is_leaf())
         return this;
     for (size_t ix = 0; ix < size(); ix++) {
         if (key < m_entries[ix]) {
             dbgln_if(SQL_DEBUG, "[{}] {} < {} v{}",
-                block_index(), (DeprecatedString)key, (DeprecatedString)m_entries[ix], m_down[ix].block_index());
+                block_index(), (ByteString)key, (ByteString)m_entries[ix], m_down[ix].block_index());
             return down_node(ix)->node_for(key);
         }
     }
     dbgln_if(SQL_DEBUG, "[#{}] {} >= {} v{}",
-        block_index(), key.to_deprecated_string(), (DeprecatedString)m_entries[size() - 1], m_down[size()].block_index());
+        block_index(), key.to_byte_string(), (ByteString)m_entries[size() - 1], m_down[size()].block_index());
     return down_node(size())->node_for(key);
 }
 
 Optional<u32> TreeNode::get(Key& key)
 {
-    dump_if(SQL_DEBUG, DeprecatedString::formatted("get({})", key.to_deprecated_string()));
+    dump_if(SQL_DEBUG, ByteString::formatted("get({})", key.to_byte_string()));
     for (auto ix = 0u; ix < size(); ix++) {
         if (key < m_entries[ix]) {
             if (is_leaf()) {
                 dbgln_if(SQL_DEBUG, "[#{}] {} < {} -> 0",
-                    block_index(), key.to_deprecated_string(), (DeprecatedString)m_entries[ix]);
+                    block_index(), key.to_byte_string(), (ByteString)m_entries[ix]);
                 return {};
             } else {
                 dbgln_if(SQL_DEBUG, "[{}] {} < {} ({} -> {})",
-                    block_index(), key.to_deprecated_string(), (DeprecatedString)m_entries[ix],
+                    block_index(), key.to_byte_string(), (ByteString)m_entries[ix],
                     ix, m_down[ix].block_index());
                 return down_node(ix)->get(key);
             }
         }
         if (key == m_entries[ix]) {
             dbgln_if(SQL_DEBUG, "[#{}] {} == {} -> {}",
-                block_index(), key.to_deprecated_string(), (DeprecatedString)m_entries[ix],
+                block_index(), key.to_byte_string(), (ByteString)m_entries[ix],
                 m_entries[ix].block_index());
             key.set_block_index(m_entries[ix].block_index());
             return m_entries[ix].block_index();
         }
     }
     if (m_entries.is_empty()) {
-        dbgln_if(SQL_DEBUG, "[#{}] {} Empty node??", block_index(), key.to_deprecated_string());
+        dbgln_if(SQL_DEBUG, "[#{}] {} Empty node??", block_index(), key.to_byte_string());
         VERIFY_NOT_REACHED();
     }
     if (is_leaf()) {
         dbgln_if(SQL_DEBUG, "[#{}] {} > {} -> 0",
-            block_index(), key.to_deprecated_string(), (DeprecatedString)m_entries[size() - 1]);
+            block_index(), key.to_byte_string(), (ByteString)m_entries[size() - 1]);
         return {};
     }
     dbgln_if(SQL_DEBUG, "[#{}] {} > {} ({} -> {})",
-        block_index(), key.to_deprecated_string(), (DeprecatedString)m_entries[size() - 1],
+        block_index(), key.to_byte_string(), (ByteString)m_entries[size() - 1],
         size(), m_down[size()].block_index());
     return down_node(size())->get(key);
 }
@@ -264,7 +264,7 @@ Optional<u32> TreeNode::get(Key& key)
 void TreeNode::just_insert(Key const& key, TreeNode* right)
 {
     dbgln_if(SQL_DEBUG, "[#{}] just_insert({}, right = {})",
-        block_index(), (DeprecatedString)key, (right) ? right->block_index() : 0);
+        block_index(), (ByteString)key, (right) ? right->block_index() : 0);
     dump_if(SQL_DEBUG, "Before");
     for (auto ix = 0u; ix < size(); ix++) {
         if (key < m_entries[ix]) {
@@ -331,7 +331,7 @@ void TreeNode::split()
     m_up->just_insert(median, new_node);
 }
 
-void TreeNode::dump_if(int flag, DeprecatedString&& msg)
+void TreeNode::dump_if(int flag, ByteString&& msg)
 {
     if (!flag)
         return;
@@ -349,7 +349,7 @@ void TreeNode::dump_if(int flag, DeprecatedString&& msg)
             builder.appendff("[v{}] ", m_down[ix].block_index());
         else
             VERIFY(m_down[ix].block_index() == 0);
-        builder.appendff("'{}' ", (DeprecatedString)m_entries[ix]);
+        builder.appendff("'{}' ", (ByteString)m_entries[ix]);
     }
     if (!is_leaf())
         builder.appendff("[v{}]", m_down[size()].block_index());
@@ -359,7 +359,7 @@ void TreeNode::dump_if(int flag, DeprecatedString&& msg)
     if (is_leaf())
         builder.append(", leaf"sv);
     builder.append(')');
-    dbgln(builder.to_deprecated_string());
+    dbgln(builder.to_byte_string());
 }
 
 void TreeNode::list_node(int indent)
@@ -374,7 +374,7 @@ void TreeNode::list_node(int indent)
         if (!is_leaf())
             down_node(ix)->list_node(indent + 2);
         do_indent();
-        warnln("{}", m_entries[ix].to_deprecated_string());
+        warnln("{}", m_entries[ix].to_byte_string());
     }
     if (!is_leaf())
         down_node(size())->list_node(indent + 2);
diff --git a/Userland/Libraries/LibSQL/Tuple.cpp b/Userland/Libraries/LibSQL/Tuple.cpp
index 543db547465..bd5da323a4d 100644
--- a/Userland/Libraries/LibSQL/Tuple.cpp
+++ b/Userland/Libraries/LibSQL/Tuple.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <LibSQL/Serializer.h>
 #include <LibSQL/Tuple.h>
@@ -84,14 +84,14 @@ Optional<size_t> Tuple::index_of(StringView name) const
     return {};
 }
 
-Value const& Tuple::operator[](DeprecatedString const& name) const
+Value const& Tuple::operator[](ByteString const& name) const
 {
     auto index = index_of(name);
     VERIFY(index.has_value());
     return (*this)[index.value()];
 }
 
-Value& Tuple::operator[](DeprecatedString const& name)
+Value& Tuple::operator[](ByteString const& name)
 {
     auto index = index_of(name);
     VERIFY(index.has_value());
@@ -132,17 +132,17 @@ size_t Tuple::length() const
     return len;
 }
 
-DeprecatedString Tuple::to_deprecated_string() const
+ByteString Tuple::to_byte_string() const
 {
     StringBuilder builder;
     for (auto& part : m_data) {
         if (!builder.is_empty())
             builder.append('|');
-        builder.append(part.to_deprecated_string());
+        builder.append(part.to_byte_string());
     }
     if (block_index() != 0)
         builder.appendff(":{}", block_index());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 void Tuple::copy_from(Tuple const& other)
diff --git a/Userland/Libraries/LibSQL/Tuple.h b/Userland/Libraries/LibSQL/Tuple.h
index ba757107c52..3aa06cbdabb 100644
--- a/Userland/Libraries/LibSQL/Tuple.h
+++ b/Userland/Libraries/LibSQL/Tuple.h
@@ -34,8 +34,8 @@ public:
 
     Tuple& operator=(Tuple const&);
 
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
-    explicit operator DeprecatedString() const { return to_deprecated_string(); }
+    [[nodiscard]] ByteString to_byte_string() const;
+    explicit operator ByteString() const { return to_byte_string(); }
 
     bool operator<(Tuple const& other) const { return compare(other) < 0; }
     bool operator<=(Tuple const& other) const { return compare(other) <= 0; }
@@ -45,12 +45,12 @@ public:
     bool operator>=(Tuple const& other) const { return compare(other) >= 0; }
 
     [[nodiscard]] bool is_null() const { return m_data.is_empty(); }
-    [[nodiscard]] bool has(DeprecatedString const& name) const { return index_of(name).has_value(); }
+    [[nodiscard]] bool has(ByteString const& name) const { return index_of(name).has_value(); }
 
     Value const& operator[](size_t ix) const { return m_data[ix]; }
     Value& operator[](size_t ix) { return m_data[ix]; }
-    Value const& operator[](DeprecatedString const& name) const;
-    Value& operator[](DeprecatedString const& name);
+    Value const& operator[](ByteString const& name) const;
+    Value& operator[](ByteString const& name);
     void append(Value const&);
     Tuple& operator+=(Value const&);
     void extend(Tuple const&);
diff --git a/Userland/Libraries/LibSQL/TupleDescriptor.h b/Userland/Libraries/LibSQL/TupleDescriptor.h
index 2082e7f3daf..4ecfd27dcad 100644
--- a/Userland/Libraries/LibSQL/TupleDescriptor.h
+++ b/Userland/Libraries/LibSQL/TupleDescriptor.h
@@ -13,9 +13,9 @@
 namespace SQL {
 
 struct TupleElementDescriptor {
-    DeprecatedString schema { "" };
-    DeprecatedString table { "" };
-    DeprecatedString name { "" };
+    ByteString schema { "" };
+    ByteString table { "" };
+    ByteString name { "" };
     SQLType type { SQLType::Text };
     Order order { Order::Ascending };
 
@@ -29,7 +29,7 @@ struct TupleElementDescriptor {
     }
     void deserialize(Serializer& serializer)
     {
-        name = serializer.deserialize<DeprecatedString>();
+        name = serializer.deserialize<ByteString>();
         type = (SQLType)serializer.deserialize<u8>();
         order = (Order)serializer.deserialize<u8>();
     }
@@ -39,9 +39,9 @@ struct TupleElementDescriptor {
         return sizeof(u32) + name.length() + 2 * sizeof(u8);
     }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
-        return DeprecatedString::formatted("  name: {} type: {} order: {}", name, SQLType_name(type), Order_name(order));
+        return ByteString::formatted("  name: {} type: {} order: {}", name, SQLType_name(type), Order_name(order));
     }
 };
 
@@ -90,12 +90,12 @@ public:
         return len;
     }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
-        Vector<DeprecatedString> elements;
+        Vector<ByteString> elements;
         for (auto& element : *this)
-            elements.append(element.to_deprecated_string());
-        return DeprecatedString::formatted("[\n{}\n]", DeprecatedString::join('\n', elements));
+            elements.append(element.to_byte_string());
+        return ByteString::formatted("[\n{}\n]", ByteString::join('\n', elements));
     }
 
     using Vector<TupleElementDescriptor>::operator==;
diff --git a/Userland/Libraries/LibSQL/Value.cpp b/Userland/Libraries/LibSQL/Value.cpp
index 6b0bb84edd9..57fddf23a4a 100644
--- a/Userland/Libraries/LibSQL/Value.cpp
+++ b/Userland/Libraries/LibSQL/Value.cpp
@@ -97,7 +97,7 @@ Value::Value(SQLType type)
 {
 }
 
-Value::Value(DeprecatedString value)
+Value::Value(ByteString value)
     : m_type(SQLType::Text)
     , m_value(move(value))
 {
@@ -214,24 +214,24 @@ bool Value::is_int() const
     return m_value.has_value() && (m_value->has<i64>() || m_value->has<u64>());
 }
 
-DeprecatedString Value::to_deprecated_string() const
+ByteString Value::to_byte_string() const
 {
     if (is_null())
         return "(null)"sv;
 
     return m_value->visit(
-        [](DeprecatedString const& value) -> DeprecatedString { return value; },
-        [](Integer auto value) -> DeprecatedString { return DeprecatedString::number(value); },
-        [](double value) -> DeprecatedString { return DeprecatedString::number(value); },
-        [](bool value) -> DeprecatedString { return value ? "true"sv : "false"sv; },
-        [](TupleValue const& value) -> DeprecatedString {
+        [](ByteString const& value) -> ByteString { return value; },
+        [](Integer auto value) -> ByteString { return ByteString::number(value); },
+        [](double value) -> ByteString { return ByteString::number(value); },
+        [](bool value) -> ByteString { return value ? "true"sv : "false"sv; },
+        [](TupleValue const& value) -> ByteString {
             StringBuilder builder;
 
             builder.append('(');
             builder.join(',', value.values);
             builder.append(')');
 
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         });
 }
 
@@ -241,7 +241,7 @@ Optional<double> Value::to_double() const
         return {};
 
     return m_value->visit(
-        [](DeprecatedString const& value) -> Optional<double> { return value.to_double(); },
+        [](ByteString const& value) -> Optional<double> { return value.to_double(); },
         [](Integer auto value) -> Optional<double> { return static_cast<double>(value); },
         [](double value) -> Optional<double> { return value; },
         [](bool value) -> Optional<double> { return static_cast<double>(value); },
@@ -254,7 +254,7 @@ Optional<bool> Value::to_bool() const
         return {};
 
     return m_value->visit(
-        [](DeprecatedString const& value) -> Optional<bool> {
+        [](ByteString const& value) -> Optional<bool> {
             if (value.equals_ignoring_ascii_case("true"sv) || value.equals_ignoring_ascii_case("t"sv))
                 return true;
             if (value.equals_ignoring_ascii_case("false"sv) || value.equals_ignoring_ascii_case("f"sv))
@@ -293,7 +293,7 @@ Value& Value::operator=(Value value)
     return *this;
 }
 
-Value& Value::operator=(DeprecatedString value)
+Value& Value::operator=(ByteString value)
 {
     m_type = SQLType::Text;
     m_value = move(value);
@@ -361,7 +361,7 @@ size_t Value::length() const
 
     // FIXME: This seems to be more of an encoded byte size rather than a length.
     return m_value->visit(
-        [](DeprecatedString const& value) -> size_t { return sizeof(u32) + value.length(); },
+        [](ByteString const& value) -> size_t { return sizeof(u32) + value.length(); },
         [](Integer auto value) -> size_t {
             return downsize_integer(value, [](auto integer, auto) {
                 return sizeof(integer);
@@ -385,7 +385,7 @@ u32 Value::hash() const
         return 0;
 
     return m_value->visit(
-        [](DeprecatedString const& value) -> u32 { return value.hash(); },
+        [](ByteString const& value) -> u32 { return value.hash(); },
         [](Integer auto value) -> u32 {
             return downsize_integer(value, [](auto integer, auto) {
                 if constexpr (sizeof(decltype(integer)) == 8)
@@ -418,7 +418,7 @@ int Value::compare(Value const& other) const
         return 1;
 
     return m_value->visit(
-        [&](DeprecatedString const& value) -> int { return value.view().compare(other.to_deprecated_string()); },
+        [&](ByteString const& value) -> int { return value.view().compare(other.to_byte_string()); },
         [&](Integer auto value) -> int {
             auto casted = other.to_int<IntegerType<decltype(value)>>();
             if (!casted.has_value())
@@ -479,7 +479,7 @@ bool Value::operator==(Value const& value) const
 
 bool Value::operator==(StringView value) const
 {
-    return to_deprecated_string() == value;
+    return to_byte_string() == value;
 }
 
 bool Value::operator==(double value) const
@@ -749,7 +749,7 @@ void Value::deserialize(Serializer& serializer)
     case SQLType::Null:
         VERIFY_NOT_REACHED();
     case SQLType::Text:
-        m_value = serializer.deserialize<DeprecatedString>();
+        m_value = serializer.deserialize<ByteString>();
         break;
     case SQLType::Integer:
         switch (type_data) {
@@ -834,7 +834,7 @@ ErrorOr<void> IPC::encode(Encoder& encoder, SQL::Value const& value)
     case SQL::SQLType::Null:
         return {};
     case SQL::SQLType::Text:
-        return encoder.encode(value.to_deprecated_string());
+        return encoder.encode(value.to_byte_string());
     case SQL::SQLType::Integer:
         return SQL::downsize_integer(value, [&](auto integer, auto) {
             return encoder.encode(integer);
@@ -865,7 +865,7 @@ ErrorOr<SQL::Value> IPC::decode(Decoder& decoder)
     case SQL::SQLType::Null:
         return SQL::Value {};
     case SQL::SQLType::Text:
-        return SQL::Value { TRY(decoder.decode<DeprecatedString>()) };
+        return SQL::Value { TRY(decoder.decode<ByteString>()) };
     case SQL::SQLType::Integer:
         switch (type_data) {
         case SQL::TypeData::Int8:
diff --git a/Userland/Libraries/LibSQL/Value.h b/Userland/Libraries/LibSQL/Value.h
index ad65999dcc0..e0436770faa 100644
--- a/Userland/Libraries/LibSQL/Value.h
+++ b/Userland/Libraries/LibSQL/Value.h
@@ -7,8 +7,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/Checked.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Format.h>
 #include <AK/Optional.h>
 #include <AK/StringView.h>
@@ -39,7 +39,7 @@ class Value {
 
 public:
     explicit Value(SQLType sql_type = SQLType::Null);
-    explicit Value(DeprecatedString);
+    explicit Value(ByteString);
     explicit Value(double);
     Value(Value const&);
     Value(Value&&);
@@ -74,7 +74,7 @@ public:
         return *m_value;
     }
 
-    [[nodiscard]] DeprecatedString to_deprecated_string() const;
+    [[nodiscard]] ByteString to_byte_string() const;
     [[nodiscard]] Optional<double> to_double() const;
     [[nodiscard]] Optional<bool> to_bool() const;
     [[nodiscard]] Optional<Vector<Value>> to_vector() const;
@@ -86,7 +86,7 @@ public:
             return {};
 
         return m_value->visit(
-            [](DeprecatedString const& value) -> Optional<T> {
+            [](ByteString const& value) -> Optional<T> {
                 if constexpr (IsSigned<T>)
                     return value.to_int<T>();
                 else
@@ -107,7 +107,7 @@ public:
     }
 
     Value& operator=(Value);
-    Value& operator=(DeprecatedString);
+    Value& operator=(ByteString);
     Value& operator=(double);
 
     Value& operator=(Integer auto value)
@@ -171,7 +171,7 @@ private:
         Vector<Value> values;
     };
 
-    using ValueType = Variant<DeprecatedString, i64, u64, double, bool, TupleValue>;
+    using ValueType = Variant<ByteString, i64, u64, double, bool, TupleValue>;
 
     static ResultOr<NonnullRefPtr<TupleDescriptor>> infer_tuple_descriptor(Vector<Value> const& values);
     Value(NonnullRefPtr<TupleDescriptor> descriptor, Vector<Value> values);
@@ -186,7 +186,7 @@ template<>
 struct AK::Formatter<SQL::Value> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, SQL::Value const& value)
     {
-        return Formatter<StringView>::format(builder, value.to_deprecated_string());
+        return Formatter<StringView>::format(builder, value.to_byte_string());
     }
 };
 
diff --git a/Userland/Libraries/LibSymbolication/Symbolication.cpp b/Userland/Libraries/LibSymbolication/Symbolication.cpp
index d2c0cff7656..7304c8531c4 100644
--- a/Userland/Libraries/LibSymbolication/Symbolication.cpp
+++ b/Userland/Libraries/LibSymbolication/Symbolication.cpp
@@ -24,7 +24,7 @@ struct CachedELF {
     NonnullOwnPtr<ELF::Image> image;
 };
 
-static HashMap<DeprecatedString, OwnPtr<CachedELF>> s_cache;
+static HashMap<ByteString, OwnPtr<CachedELF>> s_cache;
 
 enum class KernelBaseState {
     Uninitialized,
@@ -50,7 +50,7 @@ Optional<FlatPtr> kernel_base()
             return {};
         }
 
-        auto kernel_base_str = DeprecatedString { file_content.value(), NoChomp };
+        auto kernel_base_str = ByteString { file_content.value(), NoChomp };
         using AddressType = u64;
         auto maybe_kernel_base = kernel_base_str.to_uint<AddressType>();
         if (!maybe_kernel_base.has_value()) {
@@ -65,9 +65,9 @@ Optional<FlatPtr> kernel_base()
     return s_kernel_base;
 }
 
-Optional<Symbol> symbolicate(DeprecatedString const& path, FlatPtr address, IncludeSourcePosition include_source_positions)
+Optional<Symbol> symbolicate(ByteString const& path, FlatPtr address, IncludeSourcePosition include_source_positions)
 {
-    DeprecatedString full_path = path;
+    ByteString full_path = path;
     if (!path.starts_with('/')) {
         Array<StringView, 2> search_paths { "/usr/lib"sv, "/usr/local/lib"sv };
         bool found = false;
@@ -139,7 +139,7 @@ Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid, IncludeSourcePosition in
     struct RegionWithSymbols {
         FlatPtr base { 0 };
         size_t size { 0 };
-        DeprecatedString path;
+        ByteString path;
     };
 
     Vector<FlatPtr> stack;
@@ -154,7 +154,7 @@ Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid, IncludeSourcePosition in
     }
 
     {
-        auto stack_path = DeprecatedString::formatted("/proc/{}/stacks/{}", pid, tid);
+        auto stack_path = ByteString::formatted("/proc/{}/stacks/{}", pid, tid);
         auto file_or_error = Core::File::open(stack_path, Core::File::OpenMode::Read);
         if (file_or_error.is_error()) {
             warnln("Could not open {}: {}", stack_path, file_or_error.error());
@@ -180,7 +180,7 @@ Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid, IncludeSourcePosition in
     }
 
     {
-        auto vm_path = DeprecatedString::formatted("/proc/{}/vm", pid);
+        auto vm_path = ByteString::formatted("/proc/{}/vm", pid);
         auto file_or_error = Core::File::open(vm_path, Core::File::OpenMode::Read);
         if (file_or_error.is_error()) {
             warnln("Could not open {}: {}", vm_path, file_or_error.error());
@@ -201,11 +201,11 @@ Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid, IncludeSourcePosition in
 
         for (auto& region_value : json.value().as_array().values()) {
             auto& region = region_value.as_object();
-            auto name = region.get_deprecated_string("name"sv).value_or({});
+            auto name = region.get_byte_string("name"sv).value_or({});
             auto address = region.get_addr("address"sv).value_or(0);
             auto size = region.get_addr("size"sv).value_or(0);
 
-            DeprecatedString path;
+            ByteString path;
             if (name == "/usr/lib/Loader.so") {
                 path = name;
             } else if (name.ends_with(": .text"sv) || name.ends_with(": .rodata"sv)) {
diff --git a/Userland/Libraries/LibSymbolication/Symbolication.h b/Userland/Libraries/LibSymbolication/Symbolication.h
index 6df75b5269a..5c324098c02 100644
--- a/Userland/Libraries/LibSymbolication/Symbolication.h
+++ b/Userland/Libraries/LibSymbolication/Symbolication.h
@@ -6,15 +6,15 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibDebug/DebugInfo.h>
 
 namespace Symbolication {
 
 struct Symbol {
     FlatPtr address { 0 };
-    DeprecatedString name {};
-    DeprecatedString object {};
+    ByteString name {};
+    ByteString object {};
     u32 offset { 0 };
     Vector<Debug::DebugInfo::SourcePosition> source_positions;
     bool operator==(Symbol const&) const = default;
@@ -27,6 +27,6 @@ enum class IncludeSourcePosition {
 
 Optional<FlatPtr> kernel_base();
 Vector<Symbol> symbolicate_thread(pid_t pid, pid_t tid, IncludeSourcePosition = IncludeSourcePosition::Yes);
-Optional<Symbol> symbolicate(DeprecatedString const& path, FlatPtr address, IncludeSourcePosition = IncludeSourcePosition::Yes);
+Optional<Symbol> symbolicate(ByteString const& path, FlatPtr address, IncludeSourcePosition = IncludeSourcePosition::Yes);
 
 }
diff --git a/Userland/Libraries/LibSyntax/Document.cpp b/Userland/Libraries/LibSyntax/Document.cpp
index 08a1f5c2d54..ad9923353ec 100644
--- a/Userland/Libraries/LibSyntax/Document.cpp
+++ b/Userland/Libraries/LibSyntax/Document.cpp
@@ -4,9 +4,9 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/QuickSort.h>
 #include <AK/StringBuilder.h>
 #include <AK/Utf8View.h>
@@ -65,11 +65,11 @@ size_t TextDocumentLine::leading_spaces() const
     return count;
 }
 
-DeprecatedString TextDocumentLine::to_utf8() const
+ByteString TextDocumentLine::to_utf8() const
 {
     StringBuilder builder;
     builder.append(view());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 TextDocumentLine::TextDocumentLine(Document& document)
diff --git a/Userland/Libraries/LibSyntax/Document.h b/Userland/Libraries/LibSyntax/Document.h
index 0e46088fe4e..b759ad60d11 100644
--- a/Userland/Libraries/LibSyntax/Document.h
+++ b/Userland/Libraries/LibSyntax/Document.h
@@ -33,7 +33,7 @@ public:
     explicit TextDocumentLine(Document&);
     explicit TextDocumentLine(Document&, StringView);
 
-    DeprecatedString to_utf8() const;
+    ByteString to_utf8() const;
 
     Utf32View view() const { return { code_points(), length() }; }
     u32 const* code_points() const { return m_text.data(); }
diff --git a/Userland/Libraries/LibSyntax/Highlighter.h b/Userland/Libraries/LibSyntax/Highlighter.h
index 1fa86821035..fd95d9e6eb7 100644
--- a/Userland/Libraries/LibSyntax/Highlighter.h
+++ b/Userland/Libraries/LibSyntax/Highlighter.h
@@ -131,7 +131,7 @@ private:
     virtual Vector<TextDocumentFoldingRegion>& folding_regions() override { return m_folding_regions; }
     virtual Vector<TextDocumentFoldingRegion> const& folding_regions() const override { return m_folding_regions; }
 
-    virtual DeprecatedString highlighter_did_request_text() const override { return m_text; }
+    virtual ByteString highlighter_did_request_text() const override { return m_text; }
     virtual void highlighter_did_request_update() override { }
     virtual Document& highlighter_did_request_document() override { return m_document; }
     virtual TextPosition highlighter_did_request_cursor() const override { return {}; }
diff --git a/Userland/Libraries/LibSyntax/HighlighterClient.h b/Userland/Libraries/LibSyntax/HighlighterClient.h
index c524d6b60e9..7292db2ffb4 100644
--- a/Userland/Libraries/LibSyntax/HighlighterClient.h
+++ b/Userland/Libraries/LibSyntax/HighlighterClient.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <LibSyntax/Document.h>
 #include <LibSyntax/TextPosition.h>
@@ -25,7 +25,7 @@ public:
     virtual Vector<TextDocumentFoldingRegion>& folding_regions() = 0;
     virtual Vector<TextDocumentFoldingRegion> const& folding_regions() const = 0;
 
-    virtual DeprecatedString highlighter_did_request_text() const = 0;
+    virtual ByteString highlighter_did_request_text() const = 0;
     virtual void highlighter_did_request_update() = 0;
     virtual Document& highlighter_did_request_document() = 0;
     virtual TextPosition highlighter_did_request_cursor() const = 0;
@@ -36,7 +36,7 @@ public:
     void do_set_folding_regions(Vector<TextDocumentFoldingRegion> folding_regions) { highlighter_did_set_folding_regions(move(folding_regions)); }
     void do_update() { highlighter_did_request_update(); }
 
-    DeprecatedString get_text() const { return highlighter_did_request_text(); }
+    ByteString get_text() const { return highlighter_did_request_text(); }
     Document& get_document() { return highlighter_did_request_document(); }
     TextPosition get_cursor() const { return highlighter_did_request_cursor(); }
 
diff --git a/Userland/Libraries/LibTLS/HandshakeServer.cpp b/Userland/Libraries/LibTLS/HandshakeServer.cpp
index 6e236992dab..a0b42479ee9 100644
--- a/Userland/Libraries/LibTLS/HandshakeServer.cpp
+++ b/Userland/Libraries/LibTLS/HandshakeServer.cpp
@@ -146,7 +146,7 @@ ssize_t TLSv12::handle_server_hello(ReadonlyBytes buffer, WritePacketStage& writ
                 // Read out the host_name
                 if (buffer.size() - res < sni_name_length)
                     return (i8)Error::NeedMoreData;
-                m_context.extensions.SNI = DeprecatedString { (char const*)buffer.offset_pointer(res), sni_name_length };
+                m_context.extensions.SNI = ByteString { (char const*)buffer.offset_pointer(res), sni_name_length };
                 res += sni_name_length;
                 dbgln("SNI host_name: {}", m_context.extensions.SNI);
             }
@@ -160,7 +160,7 @@ ssize_t TLSv12::handle_server_hello(ReadonlyBytes buffer, WritePacketStage& writ
                         u8 alpn_size = alpn[alpn_position++];
                         if (alpn_size + alpn_position >= extension_length)
                             break;
-                        DeprecatedString alpn_str { (char const*)alpn + alpn_position, alpn_length };
+                        ByteString alpn_str { (char const*)alpn + alpn_position, alpn_length };
                         if (alpn_size && m_context.alpn.contains_slow(alpn_str)) {
                             m_context.negotiated_alpn = alpn_str;
                             dbgln("negotiated alpn: {}", alpn_str);
diff --git a/Userland/Libraries/LibTLS/Socket.cpp b/Userland/Libraries/LibTLS/Socket.cpp
index e29eb737bc0..c1a964a78ae 100644
--- a/Userland/Libraries/LibTLS/Socket.cpp
+++ b/Userland/Libraries/LibTLS/Socket.cpp
@@ -51,7 +51,7 @@ ErrorOr<size_t> TLSv12::write_some(ReadonlyBytes bytes)
     return bytes.size();
 }
 
-ErrorOr<NonnullOwnPtr<TLSv12>> TLSv12::connect(DeprecatedString const& host, u16 port, Options options)
+ErrorOr<NonnullOwnPtr<TLSv12>> TLSv12::connect(ByteString const& host, u16 port, Options options)
 {
     Core::EventLoop loop;
     OwnPtr<Core::Socket> tcp_socket = TRY(Core::TCPSocket::connect(host, port));
@@ -73,7 +73,7 @@ ErrorOr<NonnullOwnPtr<TLSv12>> TLSv12::connect(DeprecatedString const& host, u16
     return AK::Error::from_string_view(enum_to_string(static_cast<AlertDescription>(256 - result)));
 }
 
-ErrorOr<NonnullOwnPtr<TLSv12>> TLSv12::connect(DeprecatedString const& host, Core::Socket& underlying_stream, Options options)
+ErrorOr<NonnullOwnPtr<TLSv12>> TLSv12::connect(ByteString const& host, Core::Socket& underlying_stream, Options options)
 {
     TRY(underlying_stream.set_blocking(false));
     auto tls_socket = make<TLSv12>(&underlying_stream, move(options));
diff --git a/Userland/Libraries/LibTLS/TLSv12.cpp b/Userland/Libraries/LibTLS/TLSv12.cpp
index 877d377ef47..355ff1e48f3 100644
--- a/Userland/Libraries/LibTLS/TLSv12.cpp
+++ b/Userland/Libraries/LibTLS/TLSv12.cpp
@@ -107,12 +107,12 @@ bool Certificate::is_valid() const
     auto now = Core::DateTime::now();
 
     if (now < validity.not_before) {
-        dbgln("certificate expired (not yet valid, signed for {})", validity.not_before.to_deprecated_string());
+        dbgln("certificate expired (not yet valid, signed for {})", validity.not_before.to_byte_string());
         return false;
     }
 
     if (validity.not_after < now) {
-        dbgln("certificate expired (expiry date {})", validity.not_after.to_deprecated_string());
+        dbgln("certificate expired (expiry date {})", validity.not_after.to_byte_string());
         return false;
     }
 
@@ -212,7 +212,7 @@ void TLSv12::set_root_certificates(Vector<Certificate> certificates)
         }
         // FIXME: Figure out what we should do when our root certs are invalid.
 
-        m_context.root_certificates.set(MUST(cert.subject.to_string()).to_deprecated_string(), cert);
+        m_context.root_certificates.set(MUST(cert.subject.to_string()).to_byte_string(), cert);
     }
     dbgln_if(TLS_DEBUG, "{}: Set {} root certificates", this, m_context.root_certificates.size());
 }
@@ -294,7 +294,7 @@ bool Context::verify_chain(StringView host) const
             return false;
         }
 
-        auto maybe_root_certificate = root_certificates.get(issuer_string.to_deprecated_string());
+        auto maybe_root_certificate = root_certificates.get(issuer_string.to_byte_string());
         if (maybe_root_certificate.has_value()) {
             auto& root_certificate = *maybe_root_certificate;
             auto verification_correct = verify_certificate_pair(cert, root_certificate);
diff --git a/Userland/Libraries/LibTLS/TLSv12.h b/Userland/Libraries/LibTLS/TLSv12.h
index 06d404e2dac..b9ced4ba3b3 100644
--- a/Userland/Libraries/LibTLS/TLSv12.h
+++ b/Userland/Libraries/LibTLS/TLSv12.h
@@ -243,7 +243,7 @@ struct Context {
 
     struct {
         // Server Name Indicator
-        DeprecatedString SNI; // I hate your existence
+        ByteString SNI; // I hate your existence
         bool extended_master_secret { false };
     } extensions;
 
@@ -260,9 +260,9 @@ struct Context {
     // message flags
     u8 handshake_messages[11] { 0 };
     ByteBuffer user_data;
-    HashMap<DeprecatedString, Certificate> root_certificates;
+    HashMap<ByteString, Certificate> root_certificates;
 
-    Vector<DeprecatedString> alpn;
+    Vector<ByteString> alpn;
     StringView negotiated_alpn;
 
     size_t send_retries { 0 };
@@ -317,8 +317,8 @@ public:
 
     virtual void set_notifications_enabled(bool enabled) override { underlying_stream().set_notifications_enabled(enabled); }
 
-    static ErrorOr<NonnullOwnPtr<TLSv12>> connect(DeprecatedString const& host, u16 port, Options = {});
-    static ErrorOr<NonnullOwnPtr<TLSv12>> connect(DeprecatedString const& host, Core::Socket& underlying_stream, Options = {});
+    static ErrorOr<NonnullOwnPtr<TLSv12>> connect(ByteString const& host, u16 port, Options = {});
+    static ErrorOr<NonnullOwnPtr<TLSv12>> connect(ByteString const& host, Core::Socket& underlying_stream, Options = {});
 
     using StreamVariantType = Variant<OwnPtr<Core::Socket>, Core::Socket*>;
     explicit TLSv12(StreamVariantType, Options);
diff --git a/Userland/Libraries/LibTest/CrashTest.cpp b/Userland/Libraries/LibTest/CrashTest.cpp
index e642e17e513..c0b1e272f0f 100644
--- a/Userland/Libraries/LibTest/CrashTest.cpp
+++ b/Userland/Libraries/LibTest/CrashTest.cpp
@@ -18,7 +18,7 @@
 
 namespace Test {
 
-Crash::Crash(DeprecatedString test_type, Function<Crash::Failure()> crash_function, int crash_signal)
+Crash::Crash(ByteString test_type, Function<Crash::Failure()> crash_function, int crash_signal)
     : m_type(move(test_type))
     , m_crash_function(move(crash_function))
     , m_crash_signal(crash_signal)
diff --git a/Userland/Libraries/LibTest/CrashTest.h b/Userland/Libraries/LibTest/CrashTest.h
index bfc18c9a9c9..be730ebda22 100644
--- a/Userland/Libraries/LibTest/CrashTest.h
+++ b/Userland/Libraries/LibTest/CrashTest.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/Variant.h>
 
@@ -28,7 +28,7 @@ public:
 
     static constexpr int ANY_SIGNAL = -1;
 
-    Crash(DeprecatedString test_type, Function<Crash::Failure()> crash_function, int crash_signal = ANY_SIGNAL);
+    Crash(ByteString test_type, Function<Crash::Failure()> crash_function, int crash_signal = ANY_SIGNAL);
 
     bool run(RunType run_type = RunType::UsingChildProcess);
 
@@ -36,7 +36,7 @@ private:
     using Report = Variant<Failure, int>;
     bool do_report(Report report);
 
-    DeprecatedString m_type;
+    ByteString m_type;
     Function<Crash::Failure()> m_crash_function;
     int m_crash_signal;
 };
diff --git a/Userland/Libraries/LibTest/JavaScriptTestRunner.h b/Userland/Libraries/LibTest/JavaScriptTestRunner.h
index 8c6d43cf812..072570467a7 100644
--- a/Userland/Libraries/LibTest/JavaScriptTestRunner.h
+++ b/Userland/Libraries/LibTest/JavaScriptTestRunner.h
@@ -87,16 +87,16 @@
     } __testjs_flag_hook_##flag;
 
 #define TEST_ROOT(path) \
-    DeprecatedString Test::JS::g_test_root_fragment = path
+    ByteString Test::JS::g_test_root_fragment = path
 
-#define TESTJS_RUN_FILE_FUNCTION(...)                                                                                  \
-    struct __TestJS_run_file {                                                                                         \
-        __TestJS_run_file()                                                                                            \
-        {                                                                                                              \
-            ::Test::JS::g_run_file = hook;                                                                             \
-        }                                                                                                              \
-        static ::Test::JS::IntermediateRunFileResult hook(DeprecatedString const&, JS::Realm&, JS::ExecutionContext&); \
-    } __testjs_common_run_file {};                                                                                     \
+#define TESTJS_RUN_FILE_FUNCTION(...)                                                                            \
+    struct __TestJS_run_file {                                                                                   \
+        __TestJS_run_file()                                                                                      \
+        {                                                                                                        \
+            ::Test::JS::g_run_file = hook;                                                                       \
+        }                                                                                                        \
+        static ::Test::JS::IntermediateRunFileResult hook(ByteString const&, JS::Realm&, JS::ExecutionContext&); \
+    } __testjs_common_run_file {};                                                                               \
     ::Test::JS::IntermediateRunFileResult __TestJS_run_file::hook(__VA_ARGS__)
 
 namespace Test::JS {
@@ -116,33 +116,33 @@ static consteval size_t __testjs_last()
 static constexpr auto TOP_LEVEL_TEST_NAME = "__$$TOP_LEVEL$$__";
 extern RefPtr<JS::VM> g_vm;
 extern bool g_collect_on_every_allocation;
-extern DeprecatedString g_currently_running_test;
+extern ByteString g_currently_running_test;
 struct FunctionWithLength {
     JS::ThrowCompletionOr<JS::Value> (*function)(JS::VM&);
     size_t length { 0 };
 };
-extern HashMap<DeprecatedString, FunctionWithLength> s_exposed_global_functions;
-extern DeprecatedString g_test_root_fragment;
-extern DeprecatedString g_test_root;
+extern HashMap<ByteString, FunctionWithLength> s_exposed_global_functions;
+extern ByteString g_test_root_fragment;
+extern ByteString g_test_root;
 extern int g_test_argc;
 extern char** g_test_argv;
 extern Function<void()> g_main_hook;
-extern HashMap<bool*, Tuple<DeprecatedString, DeprecatedString, char>> g_extra_args;
+extern HashMap<bool*, Tuple<ByteString, ByteString, char>> g_extra_args;
 
 struct ParserError {
     JS::ParserError error;
-    DeprecatedString hint;
+    ByteString hint;
 };
 
 struct JSFileResult {
-    DeprecatedString name;
+    ByteString name;
     Optional<ParserError> error {};
     double time_taken { 0 };
     // A failed test takes precedence over a skipped test, which both have
     // precedence over a passed test
     Test::Result most_severe_test_result { Test::Result::Pass };
     Vector<Test::Suite> suites {};
-    Vector<DeprecatedString> logged_messages {};
+    Vector<ByteString> logged_messages {};
 };
 
 enum class RunFileHookResult {
@@ -151,11 +151,11 @@ enum class RunFileHookResult {
 };
 
 using IntermediateRunFileResult = AK::Result<JSFileResult, RunFileHookResult>;
-extern IntermediateRunFileResult (*g_run_file)(DeprecatedString const&, JS::Realm&, JS::ExecutionContext&);
+extern IntermediateRunFileResult (*g_run_file)(ByteString const&, JS::Realm&, JS::ExecutionContext&);
 
 class TestRunner : public ::Test::TestRunner {
 public:
-    TestRunner(DeprecatedString test_root, DeprecatedString common_path, bool print_times, bool print_progress, bool print_json, bool detailed_json)
+    TestRunner(ByteString test_root, ByteString common_path, bool print_times, bool print_progress, bool print_json, bool detailed_json)
         : ::Test::TestRunner(move(test_root), print_times, print_progress, print_json, detailed_json)
         , m_common_path(move(common_path))
     {
@@ -165,12 +165,12 @@ public:
     virtual ~TestRunner() = default;
 
 protected:
-    virtual void do_run_single_test(DeprecatedString const& test_path, size_t, size_t) override;
-    virtual Vector<DeprecatedString> get_test_paths() const override;
-    virtual JSFileResult run_file_test(DeprecatedString const& test_path);
+    virtual void do_run_single_test(ByteString const& test_path, size_t, size_t) override;
+    virtual Vector<ByteString> get_test_paths() const override;
+    virtual JSFileResult run_file_test(ByteString const& test_path);
     void print_file_result(JSFileResult const& file_result) const;
 
-    DeprecatedString m_common_path;
+    ByteString m_common_path;
 };
 
 class TestRunnerGlobalObject final : public JS::GlobalObject {
@@ -253,7 +253,7 @@ inline ErrorOr<JsonValue> get_test_results(JS::Realm& realm)
     return JsonValue();
 }
 
-inline void TestRunner::do_run_single_test(DeprecatedString const& test_path, size_t, size_t)
+inline void TestRunner::do_run_single_test(ByteString const& test_path, size_t, size_t)
 {
     auto file_result = run_file_test(test_path);
     if (!m_print_json)
@@ -263,10 +263,10 @@ inline void TestRunner::do_run_single_test(DeprecatedString const& test_path, si
         ensure_suites().extend(file_result.suites);
 }
 
-inline Vector<DeprecatedString> TestRunner::get_test_paths() const
+inline Vector<ByteString> TestRunner::get_test_paths() const
 {
-    Vector<DeprecatedString> paths;
-    iterate_directory_recursively(m_test_root, [&](DeprecatedString const& file_path) {
+    Vector<ByteString> paths;
+    iterate_directory_recursively(m_test_root, [&](ByteString const& file_path) {
         if (!file_path.ends_with(".js"sv))
             return;
         if (!file_path.ends_with("test-common.js"sv))
@@ -276,7 +276,7 @@ inline Vector<DeprecatedString> TestRunner::get_test_paths() const
     return paths;
 }
 
-inline JSFileResult TestRunner::run_file_test(DeprecatedString const& test_path)
+inline JSFileResult TestRunner::run_file_test(ByteString const& test_path)
 {
     g_currently_running_test = test_path;
 
@@ -342,7 +342,7 @@ inline JSFileResult TestRunner::run_file_test(DeprecatedString const& test_path)
     auto result = parse_script(m_common_path, *realm);
     if (result.is_error()) {
         warnln("Unable to parse test-common.js");
-        warnln("{}", result.error().error.to_deprecated_string());
+        warnln("{}", result.error().error.to_byte_string());
         warnln("{}", result.error().hint);
         cleanup_and_exit();
     }
@@ -376,21 +376,21 @@ inline JSFileResult TestRunner::run_file_test(DeprecatedString const& test_path)
     auto& arr = user_output.as_array();
     for (auto& entry : arr.indexed_properties()) {
         auto message = MUST(arr.get(entry.index()));
-        file_result.logged_messages.append(message.to_string_without_side_effects().to_deprecated_string());
+        file_result.logged_messages.append(message.to_string_without_side_effects().to_byte_string());
     }
 
-    test_json.value().as_object().for_each_member([&](DeprecatedString const& suite_name, JsonValue const& suite_value) {
+    test_json.value().as_object().for_each_member([&](ByteString const& suite_name, JsonValue const& suite_value) {
         Test::Suite suite { test_path, suite_name };
 
         VERIFY(suite_value.is_object());
 
-        suite_value.as_object().for_each_member([&](const DeprecatedString& test_name, const JsonValue& test_value) {
+        suite_value.as_object().for_each_member([&](const ByteString& test_name, const JsonValue& test_value) {
             Test::Case test { test_name, Test::Result::Fail, "", 0 };
 
             VERIFY(test_value.is_object());
             VERIFY(test_value.as_object().has("result"sv));
 
-            auto result = test_value.as_object().get_deprecated_string("result"sv);
+            auto result = test_value.as_object().get_byte_string("result"sv);
             VERIFY(result.has_value());
             auto result_string = result.value();
             if (result_string == "pass") {
@@ -401,7 +401,7 @@ inline JSFileResult TestRunner::run_file_test(DeprecatedString const& test_path)
                 m_counts.tests_failed++;
                 suite.most_severe_test_result = Test::Result::Fail;
                 VERIFY(test_value.as_object().has("details"sv));
-                auto details = test_value.as_object().get_deprecated_string("details"sv);
+                auto details = test_value.as_object().get_byte_string("details"sv);
                 VERIFY(result.has_value());
                 test.details = details.value();
             } else if (result_string == "xfail") {
@@ -462,9 +462,9 @@ inline JSFileResult TestRunner::run_file_test(DeprecatedString const& test_path)
                 detail_builder.append(error_as_error.stack_string());
             }
 
-            test_case.details = detail_builder.to_deprecated_string();
+            test_case.details = detail_builder.to_byte_string();
         } else {
-            test_case.details = error.to_string_without_side_effects().to_deprecated_string();
+            test_case.details = error.to_string_without_side_effects().to_byte_string();
         }
 
         suite.tests.append(move(test_case));
@@ -542,7 +542,7 @@ inline void TestRunner::print_file_result(JSFileResult const& file_result) const
             outln("         {}", message);
         }
         print_modifiers({ FG_RED });
-        outln("         {}", test_error.error.to_deprecated_string());
+        outln("         {}", test_error.error.to_byte_string());
         outln();
         return;
     }
diff --git a/Userland/Libraries/LibTest/JavaScriptTestRunnerMain.cpp b/Userland/Libraries/LibTest/JavaScriptTestRunnerMain.cpp
index a80438e3e6e..0111996162a 100644
--- a/Userland/Libraries/LibTest/JavaScriptTestRunnerMain.cpp
+++ b/Userland/Libraries/LibTest/JavaScriptTestRunnerMain.cpp
@@ -20,12 +20,12 @@ namespace JS {
 
 RefPtr<::JS::VM> g_vm;
 bool g_collect_on_every_allocation = false;
-DeprecatedString g_currently_running_test;
-HashMap<DeprecatedString, FunctionWithLength> s_exposed_global_functions;
+ByteString g_currently_running_test;
+HashMap<ByteString, FunctionWithLength> s_exposed_global_functions;
 Function<void()> g_main_hook;
-HashMap<bool*, Tuple<DeprecatedString, DeprecatedString, char>> g_extra_args;
-IntermediateRunFileResult (*g_run_file)(DeprecatedString const&, JS::Realm&, JS::ExecutionContext&) = nullptr;
-DeprecatedString g_test_root;
+HashMap<bool*, Tuple<ByteString, ByteString, char>> g_extra_args;
+IntermediateRunFileResult (*g_run_file)(ByteString const&, JS::Realm&, JS::ExecutionContext&) = nullptr;
+ByteString g_test_root;
 int g_test_argc;
 char** g_test_argv;
 
@@ -93,8 +93,8 @@ int main(int argc, char** argv)
     bool print_json = false;
     bool per_file = false;
     StringView specified_test_root;
-    DeprecatedString common_path;
-    DeprecatedString test_glob;
+    ByteString common_path;
+    ByteString test_glob;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(print_times, "Show duration of each test", "show-time", 't');
@@ -128,27 +128,27 @@ int main(int argc, char** argv)
     if (per_file)
         print_json = true;
 
-    test_glob = DeprecatedString::formatted("*{}*", test_glob);
+    test_glob = ByteString::formatted("*{}*", test_glob);
 
     if (getenv("DISABLE_DBG_OUTPUT")) {
         AK::set_debug_enabled(false);
     }
 
-    DeprecatedString test_root;
+    ByteString test_root;
 
     if (!specified_test_root.is_empty()) {
-        test_root = DeprecatedString { specified_test_root };
+        test_root = ByteString { specified_test_root };
     } else {
 #ifdef AK_OS_SERENITY
-        test_root = LexicalPath::join("/home/anon/Tests"sv, DeprecatedString::formatted("{}-tests", program_name.split_view('-').last())).string();
+        test_root = LexicalPath::join("/home/anon/Tests"sv, ByteString::formatted("{}-tests", program_name.split_view('-').last())).string();
 #else
         char* serenity_source_dir = getenv("SERENITY_SOURCE_DIR");
         if (!serenity_source_dir) {
             warnln("No test root given, {} requires the SERENITY_SOURCE_DIR environment variable to be set", g_program_name);
             return 1;
         }
-        test_root = DeprecatedString::formatted("{}/{}", serenity_source_dir, g_test_root_fragment);
-        common_path = DeprecatedString::formatted("{}/Userland/Libraries/LibJS/Tests/test-common.js", serenity_source_dir);
+        test_root = ByteString::formatted("{}/{}", serenity_source_dir, g_test_root_fragment);
+        common_path = ByteString::formatted("{}/Userland/Libraries/LibJS/Tests/test-common.js", serenity_source_dir);
 #endif
     }
     if (!FileSystem::is_directory(test_root)) {
@@ -165,7 +165,7 @@ int main(int argc, char** argv)
             warnln("No test root given, {} requires the SERENITY_SOURCE_DIR environment variable to be set", g_program_name);
             return 1;
         }
-        common_path = DeprecatedString::formatted("{}/Userland/Libraries/LibJS/Tests/test-common.js", serenity_source_dir);
+        common_path = ByteString::formatted("{}/Userland/Libraries/LibJS/Tests/test-common.js", serenity_source_dir);
 #endif
     }
 
@@ -174,14 +174,14 @@ int main(int argc, char** argv)
         warnln("Failed to resolve test root: {}", test_root_or_error.error());
         return 1;
     }
-    test_root = test_root_or_error.release_value().to_deprecated_string();
+    test_root = test_root_or_error.release_value().to_byte_string();
 
     auto common_path_or_error = FileSystem::real_path(common_path);
     if (common_path_or_error.is_error()) {
         warnln("Failed to resolve common path: {}", common_path_or_error.error());
         return 1;
     }
-    common_path = common_path_or_error.release_value().to_deprecated_string();
+    common_path = common_path_or_error.release_value().to_byte_string();
 
     if (chdir(test_root.characters()) < 0) {
         auto saved_errno = errno;
diff --git a/Userland/Libraries/LibTest/Results.h b/Userland/Libraries/LibTest/Results.h
index 04ff756953d..b3a3fd37d50 100644
--- a/Userland/Libraries/LibTest/Results.h
+++ b/Userland/Libraries/LibTest/Results.h
@@ -9,7 +9,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 
 namespace Test {
@@ -23,15 +23,15 @@ enum class Result {
 };
 
 struct Case {
-    DeprecatedString name;
+    ByteString name;
     Result result;
-    DeprecatedString details;
+    ByteString details;
     u64 duration_us;
 };
 
 struct Suite {
-    DeprecatedString path;
-    DeprecatedString name;
+    ByteString path;
+    ByteString name;
     // A failed test takes precedence over a skipped test, which both have
     // precedence over a passed test
     Result most_severe_test_result { Result::Pass };
diff --git a/Userland/Libraries/LibTest/TestCase.h b/Userland/Libraries/LibTest/TestCase.h
index 066e5e893af..59fb065f546 100644
--- a/Userland/Libraries/LibTest/TestCase.h
+++ b/Userland/Libraries/LibTest/TestCase.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/NonnullRefPtr.h>
 #include <AK/RefCounted.h>
@@ -31,7 +31,7 @@ inline void run_with_randomness_source(Randomized::RandomnessSource source, Test
 
 class TestCase : public RefCounted<TestCase> {
 public:
-    TestCase(DeprecatedString const& name, TestFunction&& fn, bool is_benchmark)
+    TestCase(ByteString const& name, TestFunction&& fn, bool is_benchmark)
         : m_name(name)
         , m_function(move(fn))
         , m_is_benchmark(is_benchmark)
@@ -39,10 +39,10 @@ public:
     }
 
     bool is_benchmark() const { return m_is_benchmark; }
-    DeprecatedString const& name() const { return m_name; }
+    ByteString const& name() const { return m_name; }
     TestFunction const& func() const { return m_function; }
 
-    static NonnullRefPtr<TestCase> randomized(DeprecatedString const& name, TestFunction&& test_function)
+    static NonnullRefPtr<TestCase> randomized(ByteString const& name, TestFunction&& test_function)
     {
         using namespace Randomized;
 
@@ -101,7 +101,7 @@ public:
     }
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
     TestFunction m_function;
     bool m_is_benchmark;
 };
diff --git a/Userland/Libraries/LibTest/TestRunner.h b/Userland/Libraries/LibTest/TestRunner.h
index a4c0b606349..485f26514a1 100644
--- a/Userland/Libraries/LibTest/TestRunner.h
+++ b/Userland/Libraries/LibTest/TestRunner.h
@@ -10,7 +10,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonValue.h>
@@ -29,7 +29,7 @@ public:
         return s_the;
     }
 
-    TestRunner(DeprecatedString test_root, bool print_times, bool print_progress, bool print_json, bool detailed_json = false)
+    TestRunner(ByteString test_root, bool print_times, bool print_progress, bool print_json, bool detailed_json = false)
         : m_test_root(move(test_root))
         , m_print_times(print_times)
         , m_print_progress(print_progress)
@@ -42,7 +42,7 @@ public:
 
     virtual ~TestRunner() { s_the = nullptr; }
 
-    virtual void run(DeprecatedString test_glob);
+    virtual void run(ByteString test_glob);
 
     Test::Counts const& counts() const { return m_counts; }
 
@@ -64,11 +64,11 @@ protected:
     void print_test_results() const;
     void print_test_results_as_json() const;
 
-    virtual Vector<DeprecatedString> get_test_paths() const = 0;
-    virtual void do_run_single_test(DeprecatedString const&, size_t current_test_index, size_t num_tests) = 0;
-    virtual Vector<DeprecatedString> const* get_failed_test_names() const { return nullptr; }
+    virtual Vector<ByteString> get_test_paths() const = 0;
+    virtual void do_run_single_test(ByteString const&, size_t current_test_index, size_t num_tests) = 0;
+    virtual Vector<ByteString> const* get_failed_test_names() const { return nullptr; }
 
-    DeprecatedString m_test_root;
+    ByteString m_test_root;
     bool m_print_times;
     bool m_print_progress;
     bool m_print_json;
@@ -92,7 +92,7 @@ inline void cleanup()
     exit(1);
 }
 
-inline void TestRunner::run(DeprecatedString test_glob)
+inline void TestRunner::run(ByteString test_glob)
 {
     size_t progress_counter = 0;
     auto test_paths = get_test_paths();
@@ -243,11 +243,11 @@ inline void TestRunner::print_test_results_as_json() const
 
                 auto name = suite.name;
                 if (name == "__$$TOP_LEVEL$$__"sv)
-                    name = DeprecatedString::empty();
+                    name = ByteString::empty();
 
                 auto path = LexicalPath::relative_path(suite.path, m_test_root);
 
-                tests.set(DeprecatedString::formatted("{}/{}::{}", path, name, case_.name), result_name);
+                tests.set(ByteString::formatted("{}/{}::{}", path, name, case_.name), result_name);
             }
         }
 
@@ -274,7 +274,7 @@ inline void TestRunner::print_test_results_as_json() const
         root.set("files_total", m_counts.files_total);
         root.set("duration", m_total_elapsed_time_in_ms / 1000.0);
     }
-    outln("{}", root.to_deprecated_string());
+    outln("{}", root.to_byte_string());
 }
 
 }
diff --git a/Userland/Libraries/LibTest/TestRunnerUtil.h b/Userland/Libraries/LibTest/TestRunnerUtil.h
index 05689d50606..119b4add775 100644
--- a/Userland/Libraries/LibTest/TestRunnerUtil.h
+++ b/Userland/Libraries/LibTest/TestRunnerUtil.h
@@ -22,7 +22,7 @@ inline double get_time_in_ms()
 }
 
 template<typename Callback>
-inline void iterate_directory_recursively(DeprecatedString const& directory_path, Callback callback)
+inline void iterate_directory_recursively(ByteString const& directory_path, Callback callback)
 {
     Core::DirIterator directory_iterator(directory_path, Core::DirIterator::Flags::SkipDots);
 
@@ -32,7 +32,7 @@ inline void iterate_directory_recursively(DeprecatedString const& directory_path
         if (fstatat(directory_iterator.fd(), name.characters(), &st, AT_SYMLINK_NOFOLLOW) < 0)
             continue;
         bool is_directory = S_ISDIR(st.st_mode);
-        auto full_path = DeprecatedString::formatted("{}/{}", directory_path, name);
+        auto full_path = ByteString::formatted("{}/{}", directory_path, name);
         if (is_directory && name != "/Fixtures"sv) {
             iterate_directory_recursively(full_path, callback);
         } else if (!is_directory) {
diff --git a/Userland/Libraries/LibTest/TestSuite.cpp b/Userland/Libraries/LibTest/TestSuite.cpp
index 632f14f8baa..6c99d12cca3 100644
--- a/Userland/Libraries/LibTest/TestSuite.cpp
+++ b/Userland/Libraries/LibTest/TestSuite.cpp
@@ -99,7 +99,7 @@ void disable_reporting()
     TestSuite::the().disable_reporting();
 }
 
-static DeprecatedString test_result_to_string(TestResult result)
+static ByteString test_result_to_string(TestResult result)
 {
     switch (result) {
     case TestResult::NotRun:
@@ -117,7 +117,7 @@ static DeprecatedString test_result_to_string(TestResult result)
     }
 }
 
-int TestSuite::main(DeprecatedString const& suite_name, Span<StringView> arguments)
+int TestSuite::main(ByteString const& suite_name, Span<StringView> arguments)
 {
     m_suite_name = suite_name;
 
@@ -154,7 +154,7 @@ int TestSuite::main(DeprecatedString const& suite_name, Span<StringView> argumen
     return run(matching_tests);
 }
 
-Vector<NonnullRefPtr<TestCase>> TestSuite::find_cases(DeprecatedString const& search, bool find_tests, bool find_benchmarks)
+Vector<NonnullRefPtr<TestCase>> TestSuite::find_cases(ByteString const& search, bool find_tests, bool find_benchmarks)
 {
     Vector<NonnullRefPtr<TestCase>> matches;
     for (auto& t : m_cases) {
diff --git a/Userland/Libraries/LibTest/TestSuite.h b/Userland/Libraries/LibTest/TestSuite.h
index 5080e39a4f0..2cb486e156a 100644
--- a/Userland/Libraries/LibTest/TestSuite.h
+++ b/Userland/Libraries/LibTest/TestSuite.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/Vector.h>
 #include <LibTest/Macros.h>
@@ -34,8 +34,8 @@ public:
     }
 
     int run(Vector<NonnullRefPtr<TestCase>> const&);
-    int main(DeprecatedString const& suite_name, Span<StringView> arguments);
-    Vector<NonnullRefPtr<TestCase>> find_cases(DeprecatedString const& search, bool find_tests, bool find_benchmarks);
+    int main(ByteString const& suite_name, Span<StringView> arguments);
+    Vector<NonnullRefPtr<TestCase>> find_cases(ByteString const& search, bool find_tests, bool find_benchmarks);
     void add_case(NonnullRefPtr<TestCase> const& test_case)
     {
         m_cases.append(test_case);
@@ -67,7 +67,7 @@ private:
     Vector<NonnullRefPtr<TestCase>> m_cases;
     u64 m_testtime = 0;
     u64 m_benchtime = 0;
-    DeprecatedString m_suite_name;
+    ByteString m_suite_name;
     u64 m_benchmark_repetitions = 1;
     u64 m_randomized_runs = 100;
     Function<void()> m_setup;
diff --git a/Userland/Libraries/LibThreading/Thread.cpp b/Userland/Libraries/LibThreading/Thread.cpp
index ce2fa7e3cfc..28f265830b4 100644
--- a/Userland/Libraries/LibThreading/Thread.cpp
+++ b/Userland/Libraries/LibThreading/Thread.cpp
@@ -46,7 +46,7 @@ ErrorOr<int> Thread::get_priority() const
     return scheduling_parameters.sched_priority;
 }
 
-DeprecatedString Thread::thread_name() const { return m_thread_name; }
+ByteString Thread::thread_name() const { return m_thread_name; }
 
 pthread_t Thread::tid() const { return m_tid; }
 
diff --git a/Userland/Libraries/LibThreading/Thread.h b/Userland/Libraries/LibThreading/Thread.h
index b3e7030fe3f..87a649ab6ab 100644
--- a/Userland/Libraries/LibThreading/Thread.h
+++ b/Userland/Libraries/LibThreading/Thread.h
@@ -9,7 +9,7 @@
 
 #include <AK/Assertions.h>
 #include <AK/AtomicRefCounted.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/DistinctNumeric.h>
 #include <AK/Function.h>
 #include <AK/Result.h>
@@ -69,7 +69,7 @@ public:
     template<typename T = void>
     Result<T, ThreadError> join();
 
-    DeprecatedString thread_name() const;
+    ByteString thread_name() const;
     pthread_t tid() const;
     ThreadState state() const;
     bool is_started() const;
@@ -80,7 +80,7 @@ private:
     explicit Thread(Function<intptr_t()> action, StringView thread_name = {});
     Function<intptr_t()> m_action;
     pthread_t m_tid { 0 };
-    DeprecatedString m_thread_name;
+    ByteString m_thread_name;
     Atomic<ThreadState> m_state { ThreadState::Startable };
 };
 
@@ -120,7 +120,7 @@ template<>
 struct AK::Formatter<Threading::ThreadState> : AK::Formatter<FormatString> {
     ErrorOr<void> format(FormatBuilder& builder, Threading::ThreadState state)
     {
-        DeprecatedString name = "";
+        ByteString name = "";
         switch (state) {
         case Threading::ThreadState::Detached:
             name = "Detached";
diff --git a/Userland/Libraries/LibTimeZone/TimeZone.cpp b/Userland/Libraries/LibTimeZone/TimeZone.cpp
index 4a1ef8a3b3b..03870f067d3 100644
--- a/Userland/Libraries/LibTimeZone/TimeZone.cpp
+++ b/Userland/Libraries/LibTimeZone/TimeZone.cpp
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/ScopeGuard.h>
 #include <LibTimeZone/TimeZone.h>
 #include <limits.h>
@@ -45,7 +45,7 @@ public:
         }
     }
 
-    ErrorOr<DeprecatedString> read_time_zone()
+    ErrorOr<ByteString> read_time_zone()
     {
         if (!m_file)
             return Error::from_string_literal("Could not open /etc/timezone");
@@ -56,7 +56,7 @@ public:
         if (bytes == 0)
             return Error::from_string_literal("Could not read time zone from /etc/timezone");
 
-        return DeprecatedString(buffer.span().slice(0, bytes)).trim_whitespace();
+        return ByteString(buffer.span().slice(0, bytes)).trim_whitespace();
     }
 
     ErrorOr<void> write_time_zone(StringView time_zone)
diff --git a/Userland/Libraries/LibTimeZone/TimeZone.h b/Userland/Libraries/LibTimeZone/TimeZone.h
index 5f1b18ef805..a345cc9eaa0 100644
--- a/Userland/Libraries/LibTimeZone/TimeZone.h
+++ b/Userland/Libraries/LibTimeZone/TimeZone.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <AK/Array.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Format.h>
 #include <AK/Optional.h>
@@ -40,7 +40,7 @@ struct Offset {
 };
 
 struct NamedOffset : public Offset {
-    DeprecatedString name;
+    ByteString name;
 };
 
 struct Coordinate {
diff --git a/Userland/Libraries/LibUSBDB/Database.cpp b/Userland/Libraries/LibUSBDB/Database.cpp
index d384f1a35a8..4e43a232c69 100644
--- a/Userland/Libraries/LibUSBDB/Database.cpp
+++ b/Userland/Libraries/LibUSBDB/Database.cpp
@@ -12,7 +12,7 @@
 
 namespace USBDB {
 
-RefPtr<Database> Database::open(DeprecatedString const& filename)
+RefPtr<Database> Database::open(ByteString const& filename)
 {
     auto file_or_error = Core::MappedFile::map(filename);
     if (file_or_error.is_error())
diff --git a/Userland/Libraries/LibUSBDB/Database.h b/Userland/Libraries/LibUSBDB/Database.h
index b0028fb83ae..6ad4880d39f 100644
--- a/Userland/Libraries/LibUSBDB/Database.h
+++ b/Userland/Libraries/LibUSBDB/Database.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/RefCounted.h>
@@ -52,7 +52,7 @@ struct Class {
 
 class Database : public RefCounted<Database> {
 public:
-    static RefPtr<Database> open(DeprecatedString const& filename);
+    static RefPtr<Database> open(ByteString const& filename);
     static RefPtr<Database> open() { return open("/res/usb.ids"); }
 
     const StringView get_vendor(u16 vendor_id) const;
diff --git a/Userland/Libraries/LibUnicode/CharacterTypes.cpp b/Userland/Libraries/LibUnicode/CharacterTypes.cpp
index 416243d21a1..f68b2affd32 100644
--- a/Userland/Libraries/LibUnicode/CharacterTypes.cpp
+++ b/Userland/Libraries/LibUnicode/CharacterTypes.cpp
@@ -20,7 +20,7 @@
 
 namespace Unicode {
 
-Optional<DeprecatedString> __attribute__((weak)) code_point_display_name(u32) { return {}; }
+Optional<ByteString> __attribute__((weak)) code_point_display_name(u32) { return {}; }
 Optional<StringView> __attribute__((weak)) code_point_block_display_name(u32) { return {}; }
 Optional<StringView> __attribute__((weak)) code_point_abbreviation(u32) { return {}; }
 u32 __attribute__((weak)) canonical_combining_class(u32) { return {}; }
diff --git a/Userland/Libraries/LibUnicode/CharacterTypes.h b/Userland/Libraries/LibUnicode/CharacterTypes.h
index 23c48cc9aef..e0060f8c86f 100644
--- a/Userland/Libraries/LibUnicode/CharacterTypes.h
+++ b/Userland/Libraries/LibUnicode/CharacterTypes.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/Optional.h>
 #include <AK/Span.h>
@@ -34,7 +34,7 @@ struct BlockName {
     StringView display_name;
 };
 
-Optional<DeprecatedString> code_point_display_name(u32 code_point);
+Optional<ByteString> code_point_display_name(u32 code_point);
 Optional<StringView> code_point_block_display_name(u32 code_point);
 Optional<StringView> code_point_abbreviation(u32 code_point);
 
diff --git a/Userland/Libraries/LibVT/Attribute.h b/Userland/Libraries/LibVT/Attribute.h
index bf73995c8a6..e3f7409feed 100644
--- a/Userland/Libraries/LibVT/Attribute.h
+++ b/Userland/Libraries/LibVT/Attribute.h
@@ -13,7 +13,7 @@
 #include <LibVT/XtermColors.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #endif
 
 namespace VT {
@@ -37,8 +37,8 @@ struct Attribute {
     Color background_color { default_background_color };
 
 #ifndef KERNEL
-    DeprecatedString href;
-    Optional<DeprecatedString> href_id;
+    ByteString href;
+    Optional<ByteString> href_id;
 #endif
 
     enum class Flags : u8 {
diff --git a/Userland/Libraries/LibVT/Terminal.cpp b/Userland/Libraries/LibVT/Terminal.cpp
index dcc642c328d..48619af7f66 100644
--- a/Userland/Libraries/LibVT/Terminal.cpp
+++ b/Userland/Libraries/LibVT/Terminal.cpp
@@ -1264,7 +1264,7 @@ void Terminal::execute_osc_sequence(OscParameters parameters, u8 last_byte)
             // FIXME: the split breaks titles containing semicolons.
             // Should we expose the raw OSC string from the parser? Or join by semicolon?
 #ifndef KERNEL
-            m_current_window_title = stringview_ify(1).to_deprecated_string();
+            m_current_window_title = stringview_ify(1).to_byte_string();
             m_client.set_window_title(m_current_window_title);
 #endif
         }
@@ -1280,7 +1280,7 @@ void Terminal::execute_osc_sequence(OscParameters parameters, u8 last_byte)
         } else {
             m_current_state.attribute.href = stringview_ify(2);
             // FIXME: Respect the provided ID
-            m_current_state.attribute.href_id = DeprecatedString::number(m_next_href_id++);
+            m_current_state.attribute.href_id = ByteString::number(m_next_href_id++);
         }
 #endif
         break;
diff --git a/Userland/Libraries/LibVT/Terminal.h b/Userland/Libraries/LibVT/Terminal.h
index 6e3b12dd195..fdbefb88d61 100644
--- a/Userland/Libraries/LibVT/Terminal.h
+++ b/Userland/Libraries/LibVT/Terminal.h
@@ -16,7 +16,7 @@
 #include <LibVT/Position.h>
 
 #ifndef KERNEL
-#    include <AK/DeprecatedString.h>
+#    include <AK/ByteString.h>
 #    include <LibVT/Attribute.h>
 #    include <LibVT/Line.h>
 #else
@@ -435,8 +435,8 @@ protected:
     Attribute m_saved_attribute;
 
 #ifndef KERNEL
-    DeprecatedString m_current_window_title;
-    Vector<DeprecatedString> m_title_stack;
+    ByteString m_current_window_title;
+    Vector<ByteString> m_title_stack;
 #endif
 
 #ifndef KERNEL
diff --git a/Userland/Libraries/LibVT/TerminalWidget.cpp b/Userland/Libraries/LibVT/TerminalWidget.cpp
index bfa1cbb805d..607a7e5f5ef 100644
--- a/Userland/Libraries/LibVT/TerminalWidget.cpp
+++ b/Userland/Libraries/LibVT/TerminalWidget.cpp
@@ -7,7 +7,7 @@
  */
 
 #include "TerminalWidget.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/StdLibExtras.h>
 #include <AK/StringBuilder.h>
@@ -982,7 +982,7 @@ int TerminalWidget::scroll_length() const
     return m_scrollbar->step();
 }
 
-DeprecatedString TerminalWidget::selected_text() const
+ByteString TerminalWidget::selected_text() const
 {
     StringBuilder builder;
 
@@ -1008,7 +1008,7 @@ DeprecatedString TerminalWidget::selected_text() const
         }
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 int TerminalWidget::first_selection_column_on_row(int row) const
@@ -1133,7 +1133,7 @@ void TerminalWidget::context_menu_event(GUI::ContextMenuEvent& event)
             auto af = Desktop::AppFile::get_for_app(LexicalPath::basename(handler));
             if (!af->is_valid())
                 continue;
-            auto action = GUI::Action::create(DeprecatedString::formatted("&Open in {}", af->name()), af->icon().bitmap_for_size(16), [this, handler](auto&) {
+            auto action = GUI::Action::create(ByteString::formatted("&Open in {}", af->name()), af->icon().bitmap_for_size(16), [this, handler](auto&) {
                 Desktop::Launcher::open(m_context_menu_href, handler);
             });
 
@@ -1181,7 +1181,7 @@ void TerminalWidget::drop_event(GUI::DropEvent& event)
             if (url.scheme() == "file")
                 send_non_user_input(url.serialize_path().bytes());
             else
-                send_non_user_input(url.to_deprecated_string().bytes());
+                send_non_user_input(url.to_byte_string().bytes());
 
             first = false;
         }
@@ -1360,7 +1360,7 @@ Optional<VT::CursorShape> TerminalWidget::parse_cursor_shape(StringView cursor_s
     return {};
 }
 
-DeprecatedString TerminalWidget::stringify_cursor_shape(VT::CursorShape cursor_shape)
+ByteString TerminalWidget::stringify_cursor_shape(VT::CursorShape cursor_shape)
 {
     switch (cursor_shape) {
     case VT::CursorShape::Block:
diff --git a/Userland/Libraries/LibVT/TerminalWidget.h b/Userland/Libraries/LibVT/TerminalWidget.h
index 6f85565d579..5293cff423b 100644
--- a/Userland/Libraries/LibVT/TerminalWidget.h
+++ b/Userland/Libraries/LibVT/TerminalWidget.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/ElapsedTimer.h>
 #include <LibCore/Notifier.h>
 #include <LibCore/Timer.h>
@@ -57,7 +57,7 @@ public:
 
     bool has_selection() const;
     bool selection_contains(const VT::Position&) const;
-    DeprecatedString selected_text() const;
+    ByteString selected_text() const;
     VT::Range normalized_selection() const { return m_selection.normalized(); }
     void set_selection(const VT::Range& selection);
     VT::Position buffer_position_at(Gfx::IntPoint) const;
@@ -103,7 +103,7 @@ public:
     virtual void set_cursor_shape(CursorShape) override;
 
     static Optional<VT::CursorShape> parse_cursor_shape(StringView);
-    static DeprecatedString stringify_cursor_shape(VT::CursorShape);
+    static ByteString stringify_cursor_shape(VT::CursorShape);
 
 private:
     TerminalWidget(int ptm_fd, bool automatic_size_policy);
@@ -136,7 +136,7 @@ private:
     virtual void emit(u8 const*, size_t) override;
 
     // ^GUI::Clipboard::ClipboardClient
-    virtual void clipboard_content_did_change(DeprecatedString const&) override { update_paste_action(); }
+    virtual void clipboard_content_did_change(ByteString const&) override { update_paste_action(); }
 
     void send_non_user_input(ReadonlyBytes);
 
@@ -167,21 +167,21 @@ private:
 
     VT::Range m_selection;
 
-    DeprecatedString m_hovered_href;
-    Optional<DeprecatedString> m_hovered_href_id;
+    ByteString m_hovered_href;
+    Optional<ByteString> m_hovered_href_id;
 
-    DeprecatedString m_active_href;
-    Optional<DeprecatedString> m_active_href_id;
+    ByteString m_active_href;
+    Optional<ByteString> m_active_href_id;
 
     // Snapshot of m_hovered_href when opening a context menu for a hyperlink.
-    DeprecatedString m_context_menu_href;
+    ByteString m_context_menu_href;
 
     Gfx::Color m_colors[256];
     Gfx::Color m_default_foreground_color;
     Gfx::Color m_default_background_color;
     bool m_show_bold_text_as_bright { true };
 
-    DeprecatedString m_color_scheme_name;
+    ByteString m_color_scheme_name;
 
     BellMode m_bell_mode { BellMode::Visible };
     bool m_alt_key_held { false };
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Document.h b/Userland/Libraries/LibVideo/Containers/Matroska/Document.h
index 39cce17ae56..861f230ba00 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Document.h
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Document.h
@@ -7,8 +7,8 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
+#include <AK/ByteString.h>
 #include <AK/DeprecatedFlyString.h>
-#include <AK/DeprecatedString.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/Time.h>
@@ -18,7 +18,7 @@
 namespace Video::Matroska {
 
 struct EBMLHeader {
-    DeprecatedString doc_type;
+    ByteString doc_type;
     u32 doc_type_version;
 };
 
@@ -27,9 +27,9 @@ public:
     u64 timestamp_scale() const { return m_timestamp_scale; }
     void set_timestamp_scale(u64 timestamp_scale) { m_timestamp_scale = timestamp_scale; }
     Utf8View muxing_app() const { return Utf8View(m_muxing_app); }
-    void set_muxing_app(DeprecatedString muxing_app) { m_muxing_app = move(muxing_app); }
+    void set_muxing_app(ByteString muxing_app) { m_muxing_app = move(muxing_app); }
     Utf8View writing_app() const { return Utf8View(m_writing_app); }
-    void set_writing_app(DeprecatedString writing_app) { m_writing_app = move(writing_app); }
+    void set_writing_app(ByteString writing_app) { m_writing_app = move(writing_app); }
     Optional<double> duration_unscaled() const { return m_duration_unscaled; }
     void set_duration_unscaled(double duration) { m_duration_unscaled.emplace(duration); }
     Optional<Duration> duration() const
@@ -41,8 +41,8 @@ public:
 
 private:
     u64 m_timestamp_scale { 1'000'000 };
-    DeprecatedString m_muxing_app;
-    DeprecatedString m_writing_app;
+    ByteString m_muxing_app;
+    ByteString m_writing_app;
     Optional<double> m_duration_unscaled;
 };
 
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
index 754e55ee35d..d5ac59420dd 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.cpp
@@ -980,13 +980,13 @@ DecoderErrorOr<void> SampleIterator::seek_to_cue_point(CuePoint const& cue_point
     return {};
 }
 
-ErrorOr<DeprecatedString> Streamer::read_string()
+ErrorOr<ByteString> Streamer::read_string()
 {
     auto string_length = TRY(read_variable_size_integer());
     if (remaining() < string_length)
         return Error::from_string_literal("String length extends past the end of the stream");
     auto string_data = data_as_chars();
-    auto string_value = DeprecatedString(string_data, strnlen(string_data, string_length));
+    auto string_value = ByteString(string_data, strnlen(string_data, string_length));
     TRY(read_raw_octets(string_length));
     return string_value;
 }
diff --git a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.h b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.h
index 6c7e352adee..9b297ec4e7c 100644
--- a/Userland/Libraries/LibVideo/Containers/Matroska/Reader.h
+++ b/Userland/Libraries/LibVideo/Containers/Matroska/Reader.h
@@ -145,7 +145,7 @@ public:
     ErrorOr<u64> read_u64();
     ErrorOr<double> read_float();
 
-    ErrorOr<DeprecatedString> read_string();
+    ErrorOr<ByteString> read_string();
 
     ErrorOr<void> read_unknown_element();
 
diff --git a/Userland/Libraries/LibVideo/DecoderError.h b/Userland/Libraries/LibVideo/DecoderError.h
index bca03e1c188..fc97442c58c 100644
--- a/Userland/Libraries/LibVideo/DecoderError.h
+++ b/Userland/Libraries/LibVideo/DecoderError.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Format.h>
 #include <AK/SourceLocation.h>
@@ -43,7 +43,7 @@ public:
     static DecoderError format(DecoderErrorCategory category, CheckedFormatString<Parameters...>&& format_string, Parameters const&... parameters)
     {
         AK::VariadicFormatParams<AK::AllowDebugOnlyFormatters::No, Parameters...> variadic_format_params { parameters... };
-        return DecoderError::with_description(category, DeprecatedString::vformatted(format_string.view(), variadic_format_params));
+        return DecoderError::with_description(category, ByteString::vformatted(format_string.view(), variadic_format_params));
     }
 
     static DecoderError from_source_location(DecoderErrorCategory category, StringView description, SourceLocation location = SourceLocation::current())
@@ -66,14 +66,14 @@ public:
     StringView string_literal() const { return m_description; }
 
 private:
-    DecoderError(DecoderErrorCategory category, DeprecatedString description)
+    DecoderError(DecoderErrorCategory category, ByteString description)
         : m_category(category)
         , m_description(move(description))
     {
     }
 
     DecoderErrorCategory m_category { DecoderErrorCategory::Unknown };
-    DeprecatedString m_description;
+    ByteString m_description;
 };
 
 #define DECODER_TRY(category, expression)                                                  \
diff --git a/Userland/Libraries/LibVideo/PlaybackManager.cpp b/Userland/Libraries/LibVideo/PlaybackManager.cpp
index cae18759987..05ca12a620d 100644
--- a/Userland/Libraries/LibVideo/PlaybackManager.cpp
+++ b/Userland/Libraries/LibVideo/PlaybackManager.cpp
@@ -495,7 +495,7 @@ private:
                 debug_string_builder.append("a future frame"sv);
             }
             debug_string_builder.append(", checking for error and buffering"sv);
-            dbgln_if(PLAYBACK_MANAGER_DEBUG, debug_string_builder.to_deprecated_string());
+            dbgln_if(PLAYBACK_MANAGER_DEBUG, debug_string_builder.to_byte_string());
 #endif
             if (future_frame_item.has_value()) {
                 if (future_frame_item->is_error()) {
diff --git a/Userland/Libraries/LibVideo/PlaybackManager.h b/Userland/Libraries/LibVideo/PlaybackManager.h
index f3a5bf7a941..3d85b11ad47 100644
--- a/Userland/Libraries/LibVideo/PlaybackManager.h
+++ b/Userland/Libraries/LibVideo/PlaybackManager.h
@@ -63,11 +63,11 @@ public:
 
     bool is_empty() const { return m_data.has<Empty>(); }
 
-    DeprecatedString debug_string() const
+    ByteString debug_string() const
     {
         if (is_error())
-            return DeprecatedString::formatted("{} at {}ms", error().string_literal(), timestamp().to_milliseconds());
-        return DeprecatedString::formatted("frame at {}ms", timestamp().to_milliseconds());
+            return ByteString::formatted("{} at {}ms", error().string_literal(), timestamp().to_milliseconds());
+        return ByteString::formatted("frame at {}ms", timestamp().to_milliseconds());
     }
 
 private:
diff --git a/Userland/Libraries/LibWasm/AbstractMachine/AbstractMachine.cpp b/Userland/Libraries/LibWasm/AbstractMachine/AbstractMachine.cpp
index fb00605619c..70d40456e52 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/AbstractMachine.cpp
+++ b/Userland/Libraries/LibWasm/AbstractMachine/AbstractMachine.cpp
@@ -141,7 +141,7 @@ ErrorOr<void, ValidationError> AbstractMachine::validate(Module& module)
 InstantiationResult AbstractMachine::instantiate(Module const& module, Vector<ExternValue> externs)
 {
     if (auto result = validate(const_cast<Module&>(module)); result.is_error())
-        return InstantiationError { DeprecatedString::formatted("Validation failed: {}", result.error()) };
+        return InstantiationError { ByteString::formatted("Validation failed: {}", result.error()) };
 
     auto main_module_instance_pointer = make<ModuleInstance>();
     auto& main_module_instance = *main_module_instance_pointer;
@@ -187,7 +187,7 @@ InstantiationResult AbstractMachine::instantiate(Module const& module, Vector<Ex
             });
             auto result = config.execute(interpreter).assert_wasm_result();
             if (result.is_trap())
-                instantiation_result = InstantiationError { DeprecatedString::formatted("Global value construction trapped: {}", result.trap().reason) };
+                instantiation_result = InstantiationError { ByteString::formatted("Global value construction trapped: {}", result.trap().reason) };
             else
                 global_values.append(result.values().first());
         }
@@ -214,7 +214,7 @@ InstantiationResult AbstractMachine::instantiate(Module const& module, Vector<Ex
                 });
                 auto result = config.execute(interpreter).assert_wasm_result();
                 if (result.is_trap()) {
-                    instantiation_result = InstantiationError { DeprecatedString::formatted("Element construction trapped: {}", result.trap().reason) };
+                    instantiation_result = InstantiationError { ByteString::formatted("Element construction trapped: {}", result.trap().reason) };
                     return IterationDecision::Continue;
                 }
 
@@ -267,7 +267,7 @@ InstantiationResult AbstractMachine::instantiate(Module const& module, Vector<Ex
             });
             auto result = config.execute(interpreter).assert_wasm_result();
             if (result.is_trap()) {
-                instantiation_result = InstantiationError { DeprecatedString::formatted("Element section initialisation trapped: {}", result.trap().reason) };
+                instantiation_result = InstantiationError { ByteString::formatted("Element section initialisation trapped: {}", result.trap().reason) };
                 return IterationDecision::Break;
             }
             auto d = result.values().first().to<i32>();
@@ -327,7 +327,7 @@ InstantiationResult AbstractMachine::instantiate(Module const& module, Vector<Ex
                     });
                     auto result = config.execute(interpreter).assert_wasm_result();
                     if (result.is_trap()) {
-                        instantiation_result = InstantiationError { DeprecatedString::formatted("Data section initialisation trapped: {}", result.trap().reason) };
+                        instantiation_result = InstantiationError { ByteString::formatted("Data section initialisation trapped: {}", result.trap().reason) };
                         return;
                     }
                     size_t offset = 0;
@@ -339,7 +339,7 @@ InstantiationResult AbstractMachine::instantiate(Module const& module, Vector<Ex
                         return;
                     if (main_module_instance.memories().size() <= data.index.value()) {
                         instantiation_result = InstantiationError {
-                            DeprecatedString::formatted("Data segment referenced out-of-bounds memory ({}) of max {} entries",
+                            ByteString::formatted("Data segment referenced out-of-bounds memory ({}) of max {} entries",
                                 data.index.value(), main_module_instance.memories().size())
                         };
                         return;
@@ -358,7 +358,7 @@ InstantiationResult AbstractMachine::instantiate(Module const& module, Vector<Ex
                         if (auto max = instance->type().limits().max(); max.has_value()) {
                             if (*max * Constants::page_size < data.init.size() + offset) {
                                 instantiation_result = InstantiationError {
-                                    DeprecatedString::formatted("Data segment attempted to write to out-of-bounds memory ({}) of max {} bytes",
+                                    ByteString::formatted("Data segment attempted to write to out-of-bounds memory ({}) of max {} bytes",
                                         data.init.size() + offset, instance->type().limits().max().value())
                                 };
                                 return;
@@ -384,7 +384,7 @@ InstantiationResult AbstractMachine::instantiate(Module const& module, Vector<Ex
         auto& functions = main_module_instance.functions();
         auto index = section.function().index();
         if (functions.size() <= index.value()) {
-            instantiation_result = InstantiationError { DeprecatedString::formatted("Start section function referenced invalid index {} of max {} entries", index.value(), functions.size()) };
+            instantiation_result = InstantiationError { ByteString::formatted("Start section function referenced invalid index {} of max {} entries", index.value(), functions.size()) };
             return;
         }
         invoke(functions[index.value()], {});
diff --git a/Userland/Libraries/LibWasm/AbstractMachine/AbstractMachine.h b/Userland/Libraries/LibWasm/AbstractMachine/AbstractMachine.h
index 18dbe58efd5..c4e5441dadd 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/AbstractMachine.h
+++ b/Userland/Libraries/LibWasm/AbstractMachine/AbstractMachine.h
@@ -24,13 +24,13 @@ class Configuration;
 struct Interpreter;
 
 struct InstantiationError {
-    DeprecatedString error { "Unknown error" };
+    ByteString error { "Unknown error" };
 };
 struct LinkError {
     enum OtherErrors {
         InvalidImportedModule,
     };
-    Vector<DeprecatedString> missing_imports;
+    Vector<ByteString> missing_imports;
     Vector<OtherErrors> other_errors;
 };
 
@@ -192,7 +192,7 @@ private:
 };
 
 struct Trap {
-    DeprecatedString reason;
+    ByteString reason;
 };
 
 // A variant of Result that does not include external reasons for error (JS::Completion, for now).
@@ -270,7 +270,7 @@ using ExternValue = Variant<FunctionAddress, TableAddress, MemoryAddress, Global
 
 class ExportInstance {
 public:
-    explicit ExportInstance(DeprecatedString name, ExternValue value)
+    explicit ExportInstance(ByteString name, ExternValue value)
         : m_name(move(name))
         , m_value(move(value))
     {
@@ -280,7 +280,7 @@ public:
     auto& value() const { return m_value; }
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
     ExternValue m_value;
 };
 
@@ -633,8 +633,8 @@ private:
 class Linker {
 public:
     struct Name {
-        DeprecatedString module;
-        DeprecatedString name;
+        ByteString module;
+        ByteString name;
         ImportSection::Import::ImportDesc type;
     };
 
diff --git a/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp b/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
index 8513c8ff83d..f38684dba65 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
+++ b/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.cpp
@@ -1250,7 +1250,7 @@ void BytecodeInterpreter::interpret(Configuration& configuration, InstructionPoi
     default:
     unimplemented:;
         dbgln_if(WASM_TRACE_DEBUG, "Instruction '{}' not implemented", instruction_name(instruction.opcode()));
-        m_trap = Trap { DeprecatedString::formatted("Unimplemented instruction {}", instruction_name(instruction.opcode())) };
+        m_trap = Trap { ByteString::formatted("Unimplemented instruction {}", instruction_name(instruction.opcode())) };
         return;
     }
 }
diff --git a/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.h b/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.h
index db5ab5467bd..168a18346ab 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.h
+++ b/Userland/Libraries/LibWasm/AbstractMachine/BytecodeInterpreter.h
@@ -21,12 +21,12 @@ struct BytecodeInterpreter : public Interpreter {
     virtual void interpret(Configuration&) override;
     virtual ~BytecodeInterpreter() override = default;
     virtual bool did_trap() const override { return !m_trap.has<Empty>(); }
-    virtual DeprecatedString trap_reason() const override
+    virtual ByteString trap_reason() const override
     {
         return m_trap.visit(
-            [](Empty) -> DeprecatedString { VERIFY_NOT_REACHED(); },
+            [](Empty) -> ByteString { VERIFY_NOT_REACHED(); },
             [](Trap const& trap) { return trap.reason; },
-            [](JS::Completion const& completion) { return completion.value()->to_string_without_side_effects().to_deprecated_string(); });
+            [](JS::Completion const& completion) { return completion.value()->to_string_without_side_effects().to_byte_string(); });
     }
     virtual void clear_trap() override { m_trap = Empty {}; }
 
diff --git a/Userland/Libraries/LibWasm/AbstractMachine/Interpreter.h b/Userland/Libraries/LibWasm/AbstractMachine/Interpreter.h
index 3928c8f5c37..cce7ad5b3a7 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/Interpreter.h
+++ b/Userland/Libraries/LibWasm/AbstractMachine/Interpreter.h
@@ -14,7 +14,7 @@ struct Interpreter {
     virtual ~Interpreter() = default;
     virtual void interpret(Configuration&) = 0;
     virtual bool did_trap() const = 0;
-    virtual DeprecatedString trap_reason() const = 0;
+    virtual ByteString trap_reason() const = 0;
     virtual void clear_trap() = 0;
 };
 
diff --git a/Userland/Libraries/LibWasm/AbstractMachine/Validator.cpp b/Userland/Libraries/LibWasm/AbstractMachine/Validator.cpp
index a82d04f5172..1815a937a4b 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/Validator.cpp
+++ b/Userland/Libraries/LibWasm/AbstractMachine/Validator.cpp
@@ -328,7 +328,7 @@ ErrorOr<void, ValidationError> Validator::validate(Limits const& limits, size_t
 template<u64 opcode>
 ErrorOr<void, ValidationError> Validator::validate_instruction(Instruction const& instruction, Stack&, bool&)
 {
-    return Errors::invalid(DeprecatedString::formatted("instruction opcode (0x{:x}) (missing validation!)", instruction.opcode().value()));
+    return Errors::invalid(ByteString::formatted("instruction opcode (0x{:x}) (missing validation!)", instruction.opcode().value()));
 }
 
 #define VALIDATE_INSTRUCTION(name) \
@@ -3774,7 +3774,7 @@ ErrorOr<void, ValidationError> Validator::validate(Instruction const& instructio
 #undef M
     default:
         is_constant = false;
-        return Errors::invalid(DeprecatedString::formatted("instruction opcode (0x{:x})", instruction.opcode().value()));
+        return Errors::invalid(ByteString::formatted("instruction opcode (0x{:x})", instruction.opcode().value()));
     }
 }
 
@@ -3851,16 +3851,16 @@ bool Validator::Stack::operator==(Stack const& other) const
     return true;
 }
 
-DeprecatedString Validator::Errors::find_instruction_name(SourceLocation const& location)
+ByteString Validator::Errors::find_instruction_name(SourceLocation const& location)
 {
     auto index = location.function_name().find('<');
     auto end_index = location.function_name().find('>');
     if (!index.has_value() || !end_index.has_value())
-        return DeprecatedString::formatted("{}", location);
+        return ByteString::formatted("{}", location);
 
     auto opcode = location.function_name().substring_view(index.value() + 1, end_index.value() - index.value() - 1).to_uint();
     if (!opcode.has_value())
-        return DeprecatedString::formatted("{}", location);
+        return ByteString::formatted("{}", location);
 
     return instruction_name(OpCode { *opcode });
 }
diff --git a/Userland/Libraries/LibWasm/AbstractMachine/Validator.h b/Userland/Libraries/LibWasm/AbstractMachine/Validator.h
index ad3710c3983..bcf7377487e 100644
--- a/Userland/Libraries/LibWasm/AbstractMachine/Validator.h
+++ b/Userland/Libraries/LibWasm/AbstractMachine/Validator.h
@@ -32,13 +32,13 @@ struct Context {
 };
 
 struct ValidationError : public Error {
-    ValidationError(DeprecatedString error)
+    ValidationError(ByteString error)
         : Error(Error::from_string_view(error.view()))
         , error_string(move(error))
     {
     }
 
-    DeprecatedString error_string;
+    ByteString error_string;
 };
 
 class Validator {
@@ -267,27 +267,27 @@ private:
     }
 
     struct Errors {
-        static ValidationError invalid(StringView name) { return DeprecatedString::formatted("Invalid {}", name); }
+        static ValidationError invalid(StringView name) { return ByteString::formatted("Invalid {}", name); }
 
         template<typename Expected, typename Given>
         static ValidationError invalid(StringView name, Expected expected, Given given, SourceLocation location = SourceLocation::current())
         {
             if constexpr (WASM_VALIDATOR_DEBUG)
-                return DeprecatedString::formatted("Invalid {} in {}, expected {} but got {}", name, find_instruction_name(location), expected, given);
+                return ByteString::formatted("Invalid {} in {}, expected {} but got {}", name, find_instruction_name(location), expected, given);
             else
-                return DeprecatedString::formatted("Invalid {}, expected {} but got {}", name, expected, given);
+                return ByteString::formatted("Invalid {}, expected {} but got {}", name, expected, given);
         }
 
         template<typename... Args>
         static ValidationError non_conforming_types(StringView name, Args... args)
         {
-            return DeprecatedString::formatted("Non-conforming types for {}: {}", name, Vector { args... });
+            return ByteString::formatted("Non-conforming types for {}: {}", name, Vector { args... });
         }
 
-        static ValidationError duplicate_export_name(StringView name) { return DeprecatedString::formatted("Duplicate exported name '{}'", name); }
+        static ValidationError duplicate_export_name(StringView name) { return ByteString::formatted("Duplicate exported name '{}'", name); }
 
         template<typename T, typename U, typename V>
-        static ValidationError out_of_bounds(StringView name, V value, T min, U max) { return DeprecatedString::formatted("Value {} for {} is out of bounds ({},{})", value, name, min, max); }
+        static ValidationError out_of_bounds(StringView name, V value, T min, U max) { return ByteString::formatted("Value {} for {} is out of bounds ({},{})", value, name, min, max); }
 
         template<typename... Expected>
         static ValidationError invalid_stack_state(Stack const& stack, Tuple<Expected...> expected, SourceLocation location = SourceLocation::current())
@@ -318,11 +318,11 @@ private:
                 }
             }
             builder.append(']');
-            return { builder.to_deprecated_string() };
+            return { builder.to_byte_string() };
         }
 
     private:
-        static DeprecatedString find_instruction_name(SourceLocation const&);
+        static ByteString find_instruction_name(SourceLocation const&);
     };
 
     enum class ChildScopeKind {
diff --git a/Userland/Libraries/LibWasm/Parser/Parser.cpp b/Userland/Libraries/LibWasm/Parser/Parser.cpp
index 0465cc29f5d..8a11fbdba44 100644
--- a/Userland/Libraries/LibWasm/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWasm/Parser/Parser.cpp
@@ -75,14 +75,14 @@ static auto parse_vector(Stream& stream)
     }
 }
 
-static ParseResult<DeprecatedString> parse_name(Stream& stream)
+static ParseResult<ByteString> parse_name(Stream& stream)
 {
     ScopeLogger<WASM_BINPARSER_DEBUG> logger;
     auto data = parse_vector<u8>(stream);
     if (data.is_error())
         return data.error();
 
-    return DeprecatedString::copy(data.value());
+    return ByteString::copy(data.value());
 }
 
 template<typename T>
@@ -1725,7 +1725,7 @@ bool Module::populate_sections()
     return is_ok;
 }
 
-DeprecatedString parse_error_to_deprecated_string(ParseError error)
+ByteString parse_error_to_byte_string(ParseError error)
 {
     switch (error) {
     case ParseError::UnexpectedEof:
diff --git a/Userland/Libraries/LibWasm/Printer/Printer.cpp b/Userland/Libraries/LibWasm/Printer/Printer.cpp
index 23858e46c1f..28d6571bcef 100644
--- a/Userland/Libraries/LibWasm/Printer/Printer.cpp
+++ b/Userland/Libraries/LibWasm/Printer/Printer.cpp
@@ -12,11 +12,11 @@
 namespace Wasm {
 
 struct Names {
-    static HashMap<OpCode, DeprecatedString> instruction_names;
-    static HashMap<DeprecatedString, OpCode> instructions_by_name;
+    static HashMap<OpCode, ByteString> instruction_names;
+    static HashMap<ByteString, OpCode> instructions_by_name;
 };
 
-DeprecatedString instruction_name(OpCode const& opcode)
+ByteString instruction_name(OpCode const& opcode)
 {
     return Names::instruction_names.get(opcode).value_or("<unknown>");
 }
@@ -131,13 +131,13 @@ void Printer::print(Wasm::DataSection::Data const& data)
             [this](DataSection::Data::Passive const& value) {
                 print_indent();
                 print("(passive init {}xu8 (", value.init.size());
-                print(DeprecatedString::join(' ', value.init, "{:x}"sv));
+                print(ByteString::join(' ', value.init, "{:x}"sv));
                 print(")\n");
             },
             [this](DataSection::Data::Active const& value) {
                 print_indent();
                 print("(active init {}xu8 (", value.init.size());
-                print(DeprecatedString::join(' ', value.init, "{:x}"sv));
+                print(ByteString::join(' ', value.init, "{:x}"sv));
                 print("\n");
                 {
                     TemporaryChange change { m_indent, m_indent + 1 };
@@ -450,7 +450,7 @@ void Printer::print(Wasm::Instruction const& instruction)
                 TemporaryChange change { m_indent, m_indent + 1 };
                 print(args.block_type);
                 print_indent();
-                print("(else {}) (end {}))", args.else_ip.has_value() ? DeprecatedString::number(args.else_ip->value()) : "(none)", args.end_ip.value());
+                print("(else {}) (end {}))", args.else_ip.has_value() ? ByteString::number(args.else_ip->value()) : "(none)", args.end_ip.value());
             },
             [&](Instruction::TableBranchArgs const& args) {
                 print("(table_branch");
@@ -650,15 +650,15 @@ void Printer::print(Wasm::Value const& value)
     print_indent();
     print("{} ", value.value().visit([&]<typename T>(T const& value) {
         if constexpr (IsSame<Wasm::Reference, T>) {
-            return DeprecatedString::formatted(
+            return ByteString::formatted(
                 "addr({})",
                 value.ref().visit(
-                    [](Wasm::Reference::Null const&) { return DeprecatedString("null"); },
-                    [](auto const& ref) { return DeprecatedString::number(ref.address.value()); }));
+                    [](Wasm::Reference::Null const&) { return ByteString("null"); },
+                    [](auto const& ref) { return ByteString::number(ref.address.value()); }));
         } else if constexpr (IsSame<u128, T>) {
-            return DeprecatedString::formatted("v128({:x})", value);
+            return ByteString::formatted("v128({:x})", value);
         } else {
-            return DeprecatedString::formatted("{}", value);
+            return ByteString::formatted("{}", value);
         }
     }));
     TemporaryChange<size_t> change { m_indent, 0 };
@@ -671,12 +671,12 @@ void Printer::print(Wasm::Reference const& value)
     print(
         "addr({})\n",
         value.ref().visit(
-            [](Wasm::Reference::Null const&) { return DeprecatedString("null"); },
-            [](auto const& ref) { return DeprecatedString::number(ref.address.value()); }));
+            [](Wasm::Reference::Null const&) { return ByteString("null"); },
+            [](auto const& ref) { return ByteString::number(ref.address.value()); }));
 }
 }
 
-HashMap<Wasm::OpCode, DeprecatedString> Wasm::Names::instruction_names {
+HashMap<Wasm::OpCode, ByteString> Wasm::Names::instruction_names {
     { Instructions::unreachable, "unreachable" },
     { Instructions::nop, "nop" },
     { Instructions::block, "block" },
@@ -1115,4 +1115,4 @@ HashMap<Wasm::OpCode, DeprecatedString> Wasm::Names::instruction_names {
     { Instructions::structured_else, "synthetic:else" },
     { Instructions::structured_end, "synthetic:end" },
 };
-HashMap<DeprecatedString, Wasm::OpCode> Wasm::Names::instructions_by_name;
+HashMap<ByteString, Wasm::OpCode> Wasm::Names::instructions_by_name;
diff --git a/Userland/Libraries/LibWasm/Printer/Printer.h b/Userland/Libraries/LibWasm/Printer/Printer.h
index 760e2533829..4d1b87322c4 100644
--- a/Userland/Libraries/LibWasm/Printer/Printer.h
+++ b/Userland/Libraries/LibWasm/Printer/Printer.h
@@ -13,7 +13,7 @@ namespace Wasm {
 class Reference;
 class Value;
 
-DeprecatedString instruction_name(OpCode const& opcode);
+ByteString instruction_name(OpCode const& opcode);
 Optional<OpCode> instruction_from_name(StringView name);
 
 struct Printer {
diff --git a/Userland/Libraries/LibWasm/Types.h b/Userland/Libraries/LibWasm/Types.h
index fb4f3015827..31891e810a0 100644
--- a/Userland/Libraries/LibWasm/Types.h
+++ b/Userland/Libraries/LibWasm/Types.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <AK/Badge.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/DistinctNumeric.h>
 #include <AK/LEB128.h>
 #include <AK/Result.h>
@@ -55,7 +55,7 @@ enum class ParseError {
     NotImplemented,
 };
 
-DeprecatedString parse_error_to_deprecated_string(ParseError);
+ByteString parse_error_to_byte_string(ParseError);
 
 template<typename T>
 using ParseResult = Result<T, ParseError>;
@@ -178,7 +178,7 @@ public:
 
     static ParseResult<ValueType> parse(Stream& stream);
 
-    static DeprecatedString kind_name(Kind kind)
+    static ByteString kind_name(Kind kind)
     {
         switch (kind) {
         case I32:
@@ -501,7 +501,7 @@ class CustomSection {
 public:
     static constexpr u8 section_id = 0;
 
-    CustomSection(DeprecatedString name, ByteBuffer contents)
+    CustomSection(ByteString name, ByteBuffer contents)
         : m_name(move(name))
         , m_contents(move(contents))
     {
@@ -513,7 +513,7 @@ public:
     static ParseResult<CustomSection> parse(Stream& stream);
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
     ByteBuffer m_contents;
 };
 
@@ -539,7 +539,7 @@ public:
     class Import {
     public:
         using ImportDesc = Variant<TypeIndex, TableType, MemoryType, GlobalType, FunctionType>;
-        Import(DeprecatedString module, DeprecatedString name, ImportDesc description)
+        Import(ByteString module, ByteString name, ImportDesc description)
             : m_module(move(module))
             , m_name(move(name))
             , m_description(move(description))
@@ -562,8 +562,8 @@ public:
             return Import { module.release_value(), name.release_value(), result.release_value() };
         }
 
-        DeprecatedString m_module;
-        DeprecatedString m_name;
+        ByteString m_module;
+        ByteString m_name;
         ImportDesc m_description;
     };
 
@@ -724,7 +724,7 @@ private:
 public:
     class Export {
     public:
-        explicit Export(DeprecatedString name, ExportDesc description)
+        explicit Export(ByteString name, ExportDesc description)
             : m_name(move(name))
             , m_description(move(description))
         {
@@ -736,7 +736,7 @@ public:
         static ParseResult<Export> parse(Stream& stream);
 
     private:
-        DeprecatedString m_name;
+        ByteString m_name;
         ExportDesc m_description;
     };
 
@@ -1077,7 +1077,7 @@ public:
     void set_validation_status(ValidationStatus status, Badge<Validator>) { set_validation_status(status); }
     ValidationStatus validation_status() const { return m_validation_status; }
     StringView validation_error() const { return *m_validation_error; }
-    void set_validation_error(DeprecatedString error) { m_validation_error = move(error); }
+    void set_validation_error(ByteString error) { m_validation_error = move(error); }
 
     static ParseResult<Module> parse(Stream& stream);
 
@@ -1088,6 +1088,6 @@ private:
     Vector<AnySection> m_sections;
     Vector<Function> m_functions;
     ValidationStatus m_validation_status { ValidationStatus::Unchecked };
-    Optional<DeprecatedString> m_validation_error;
+    Optional<ByteString> m_validation_error;
 };
 }
diff --git a/Userland/Libraries/LibWasm/WASI/Wasi.cpp b/Userland/Libraries/LibWasm/WASI/Wasi.cpp
index c00f756ce22..d5aed595a47 100644
--- a/Userland/Libraries/LibWasm/WASI/Wasi.cpp
+++ b/Userland/Libraries/LibWasm/WASI/Wasi.cpp
@@ -519,7 +519,7 @@ ErrorOr<Result<FileStat>> Implementation::impl$path_filestat_get(Configuration&
         [&](PreopenedDirectoryDescriptor descriptor) {
             auto& entry = preopened_directories()[descriptor.value()];
             dir_fd = entry.opened_fd.value_or_lazy_evaluated([&] {
-                DeprecatedString path = entry.host_path.string();
+                ByteString path = entry.host_path.string();
                 return open(path.characters(), O_DIRECTORY, 0);
             });
             entry.opened_fd = dir_fd;
@@ -537,7 +537,7 @@ ErrorOr<Result<FileStat>> Implementation::impl$path_filestat_get(Configuration&
         options |= AT_SYMLINK_NOFOLLOW;
 
     auto slice = TRY(slice_typed_memory(configuration, path, path_len));
-    auto null_terminated_string = DeprecatedString::copy(slice);
+    auto null_terminated_string = ByteString::copy(slice);
 
     struct stat stat_buf;
     if (fstatat(dir_fd, null_terminated_string.characters(), &stat_buf, options) < 0)
@@ -582,7 +582,7 @@ ErrorOr<Result<void>> Implementation::impl$path_create_directory(Configuration&
         [&](PreopenedDirectoryDescriptor descriptor) {
             auto& entry = preopened_directories()[descriptor.value()];
             dir_fd = entry.opened_fd.value_or_lazy_evaluated([&] {
-                DeprecatedString path = entry.host_path.string();
+                ByteString path = entry.host_path.string();
                 return open(path.characters(), O_DIRECTORY, 0);
             });
             entry.opened_fd = dir_fd;
@@ -596,7 +596,7 @@ ErrorOr<Result<void>> Implementation::impl$path_create_directory(Configuration&
         return errno_value_from_errno(errno);
 
     auto slice = TRY(slice_typed_memory(configuration, path, path_len));
-    auto null_terminated_string = DeprecatedString::copy(slice);
+    auto null_terminated_string = ByteString::copy(slice);
 
     if (mkdirat(dir_fd, null_terminated_string.characters(), 0755) < 0)
         return errno_value_from_errno(errno);
@@ -613,7 +613,7 @@ ErrorOr<Result<FD>> Implementation::impl$path_open(Configuration& configuration,
         [&](PreopenedDirectoryDescriptor descriptor) {
             auto& entry = preopened_directories()[descriptor.value()];
             dir_fd = entry.opened_fd.value_or_lazy_evaluated([&] {
-                DeprecatedString path = entry.host_path.string();
+                ByteString path = entry.host_path.string();
                 return open(path.characters(), O_DIRECTORY, 0);
             });
             entry.opened_fd = dir_fd;
@@ -649,7 +649,7 @@ ErrorOr<Result<FD>> Implementation::impl$path_open(Configuration& configuration,
         open_flags |= O_NOFOLLOW;
 
     auto path_data = TRY(slice_typed_memory(configuration, path, path_len));
-    auto path_string = DeprecatedString::copy(path_data);
+    auto path_string = ByteString::copy(path_data);
 
     dbgln_if(WASI_FINE_GRAINED_DEBUG, "path_open: dir_fd={}, path={}, open_flags={}", dir_fd, path_string, open_flags);
 
@@ -705,7 +705,7 @@ ErrorOr<Result<FileStat>> Implementation::impl$fd_filestat_get(Configuration&, F
         [&](PreopenedDirectoryDescriptor descriptor) {
             auto& entry = preopened_directories()[descriptor.value()];
             resolved_fd = entry.opened_fd.value_or_lazy_evaluated([&] {
-                DeprecatedString path = entry.host_path.string();
+                ByteString path = entry.host_path.string();
                 return open(path.characters(), O_DIRECTORY, 0);
             });
             entry.opened_fd = resolved_fd;
@@ -937,7 +937,7 @@ struct InvocationOf<impl> {
                 auto result = args.apply_as_args([&](auto&&... impl_args) { return (self.*impl)(configuration, impl_args...); });
                 dbgln_if(WASI_DEBUG, "WASI: {}({}) = {}", function_name, arguments, result);
                 if (result.is_error())
-                    return Wasm::Trap { DeprecatedString::formatted("Invalid call to {}() = {}", function_name, result.error()) };
+                    return Wasm::Trap { ByteString::formatted("Invalid call to {}() = {}", function_name, result.error()) };
 
                 auto value = result.release_value();
                 if (value.is_error())
diff --git a/Userland/Libraries/LibWeb/Bindings/LegacyPlatformObject.cpp b/Userland/Libraries/LibWeb/Bindings/LegacyPlatformObject.cpp
index 95f2ee7f087..fdaf1363af1 100644
--- a/Userland/Libraries/LibWeb/Bindings/LegacyPlatformObject.cpp
+++ b/Userland/Libraries/LibWeb/Bindings/LegacyPlatformObject.cpp
@@ -174,7 +174,7 @@ JS::ThrowCompletionOr<bool> LegacyPlatformObject::internal_set(JS::PropertyKey c
         // 2. If O implements an interface with a named property setter and Type(P) is String, then:
         if (has_named_property_setter() && property_name.is_string()) {
             // 1. Invoke the named property setter on O with P and V.
-            TRY(throw_dom_exception_if_needed(vm, [&] { return invoke_named_property_setter(MUST(String::from_deprecated_string(property_name.as_string())), value); }));
+            TRY(throw_dom_exception_if_needed(vm, [&] { return invoke_named_property_setter(MUST(String::from_byte_string(property_name.as_string())), value); }));
 
             // 2. Return true.
             return true;
@@ -220,7 +220,7 @@ JS::ThrowCompletionOr<bool> LegacyPlatformObject::internal_define_own_property(J
         // 1. Let creating be true if P is not a supported property name, and false otherwise.
         // NOTE: This is in it's own variable to enforce the type.
         Vector<String> supported_property_names = this->supported_property_names();
-        bool creating = !supported_property_names.contains_slow(MUST(String::from_deprecated_string(property_name_as_string)));
+        bool creating = !supported_property_names.contains_slow(MUST(String::from_byte_string(property_name_as_string)));
 
         // 2. If O implements an interface with the [LegacyOverrideBuiltIns] extended attribute or O does not have an own property named P, then:
         // NOTE: Own property lookup has to be done manually instead of using Object::has_own_property, as that would use the overridden internal_get_own_property.
@@ -236,7 +236,7 @@ JS::ThrowCompletionOr<bool> LegacyPlatformObject::internal_define_own_property(J
                     return false;
 
                 // 2. Invoke the named property setter on O with P and Desc.[[Value]].
-                TRY(throw_dom_exception_if_needed(vm, [&] { return invoke_named_property_setter(MUST(String::from_deprecated_string(property_name_as_string)), property_descriptor.value.value()); }));
+                TRY(throw_dom_exception_if_needed(vm, [&] { return invoke_named_property_setter(MUST(String::from_byte_string(property_name_as_string)), property_descriptor.value.value()); }));
 
                 // 3. Return true.
                 return true;
@@ -291,7 +291,7 @@ JS::ThrowCompletionOr<bool> LegacyPlatformObject::internal_delete(JS::PropertyKe
         // 4. Otherwise, operation was defined with an identifier:
         //    1. Perform method steps of operation with O as this and « P » as the argument values.
         //    2. If operation was declared with a return type of boolean and the steps returned false, then return false.
-        auto did_deletion_fail = TRY(throw_dom_exception_if_needed(vm, [&] { return delete_value(MUST(String::from_deprecated_string(property_name_string))); }));
+        auto did_deletion_fail = TRY(throw_dom_exception_if_needed(vm, [&] { return delete_value(MUST(String::from_byte_string(property_name_string))); }));
         if (!named_property_deleter_has_identifier())
             VERIFY(did_deletion_fail != DidDeletionFail::NotRelevant);
 
@@ -348,7 +348,7 @@ JS::ThrowCompletionOr<JS::MarkedVector<JS::Value>> LegacyPlatformObject::interna
     // 3. If O supports named properties, then for each P of O’s supported property names that is visible according to the named property visibility algorithm, append P to keys.
     if (supports_named_properties()) {
         for (auto& named_property : supported_property_names()) {
-            if (TRY(WebIDL::is_named_property_exposed_on_object({ this }, named_property.to_deprecated_string())))
+            if (TRY(WebIDL::is_named_property_exposed_on_object({ this }, named_property.to_byte_string())))
                 keys.append(JS::PrimitiveString::create(vm, named_property));
         }
     }
diff --git a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
index 18fef149ccf..6973af2d61b 100644
--- a/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
+++ b/Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp
@@ -377,7 +377,7 @@ ErrorOr<void> initialize_main_thread_vm()
 
             // 2. Let url be the result of resolving a module specifier given moduleScript and specifier.
             auto url = TRY(Bindings::throw_dom_exception_if_needed(vm, [&] {
-                return HTML::resolve_module_specifier(*module_script, specifier_string.to_deprecated_string());
+                return HTML::resolve_module_specifier(*module_script, specifier_string.to_byte_string());
             }));
 
             // 3. Return the serialization of url.
@@ -399,7 +399,7 @@ ErrorOr<void> initialize_main_thread_vm()
     // FIXME: Implement 8.1.5.5.3 HostResolveImportedModule(referencingScriptOrModule, moduleRequest), https://html.spec.whatwg.org/multipage/webappapis.html#hostresolveimportedmodule(referencingscriptormodule,-modulerequest)
 
     // 8.1.6.5.2 HostGetSupportedImportAttributes(), https://html.spec.whatwg.org/multipage/webappapis.html#hostgetsupportedimportassertions
-    s_main_thread_vm->host_get_supported_import_attributes = []() -> Vector<DeprecatedString> {
+    s_main_thread_vm->host_get_supported_import_attributes = []() -> Vector<ByteString> {
         // 1. Return « "type" ».
         return { "type"sv };
     };
@@ -487,7 +487,7 @@ ErrorOr<void> initialize_main_thread_vm()
             auto completion = [&]() -> JS::ThrowCompletionOr<JS::NonnullGCPtr<JS::Module>> {
                 // 2. If moduleScript is null, then set completion to Completion Record { [[Type]]: throw, [[Value]]: a new TypeError, [[Target]]: empty }.
                 if (!module_script) {
-                    return JS::throw_completion(JS::TypeError::create(realm, DeprecatedString::formatted("Loading imported module '{}' failed.", module_request.module_specifier)));
+                    return JS::throw_completion(JS::TypeError::create(realm, ByteString::formatted("Loading imported module '{}' failed.", module_request.module_specifier)));
                 }
                 // 3. Otherwise, if moduleScript's parse error is not null, then:
                 else if (!module_script->parse_error().is_null()) {
diff --git a/Userland/Libraries/LibWeb/Bindings/PlatformObject.h b/Userland/Libraries/LibWeb/Bindings/PlatformObject.h
index 5e855376d83..f63abc9149f 100644
--- a/Userland/Libraries/LibWeb/Bindings/PlatformObject.h
+++ b/Userland/Libraries/LibWeb/Bindings/PlatformObject.h
@@ -12,13 +12,13 @@
 
 namespace Web::Bindings {
 
-#define WEB_PLATFORM_OBJECT(class_, base_class)                                         \
-    JS_OBJECT(class_, base_class)                                                       \
-    virtual bool implements_interface(DeprecatedString const& interface) const override \
-    {                                                                                   \
-        if (interface == #class_)                                                       \
-            return true;                                                                \
-        return Base::implements_interface(interface);                                   \
+#define WEB_PLATFORM_OBJECT(class_, base_class)                                   \
+    JS_OBJECT(class_, base_class)                                                 \
+    virtual bool implements_interface(ByteString const& interface) const override \
+    {                                                                             \
+        if (interface == #class_)                                                 \
+            return true;                                                          \
+        return Base::implements_interface(interface);                             \
     }
 
 // https://webidl.spec.whatwg.org/#dfn-platform-object
@@ -37,7 +37,7 @@ public:
 
     // https://webidl.spec.whatwg.org/#implements
     // This is implemented by overrides that get generated by the WEB_PLATFORM_OBJECT macro.
-    [[nodiscard]] virtual bool implements_interface(DeprecatedString const&) const { return false; }
+    [[nodiscard]] virtual bool implements_interface(ByteString const&) const { return false; }
 
 protected:
     explicit PlatformObject(JS::Realm&, MayInterfereWithIndexedPropertyAccess = MayInterfereWithIndexedPropertyAccess::No);
diff --git a/Userland/Libraries/LibWeb/DOM/Document.cpp b/Userland/Libraries/LibWeb/DOM/Document.cpp
index 8df330c9c42..c3d2b1627e9 100644
--- a/Userland/Libraries/LibWeb/DOM/Document.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Document.cpp
@@ -291,7 +291,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Document>> Document::create_and_initialize(
 
         // 3. If referrer is a URL record, then set document's referrer to the serialization of referrer.
         if (referrer.has<AK::URL>()) {
-            document->m_referrer = MUST(String::from_deprecated_string(referrer.get<AK::URL>().serialize()));
+            document->m_referrer = MUST(String::from_byte_string(referrer.get<AK::URL>().serialize()));
         }
     }
 
@@ -804,7 +804,7 @@ WebIDL::ExceptionOr<void> Document::set_title(String const& title)
     }
 
     if (browsing_context() == &page().top_level_browsing_context())
-        page().client().page_did_change_title(title.to_deprecated_string());
+        page().client().page_did_change_title(title.to_byte_string());
 
     return {};
 }
@@ -1206,7 +1206,7 @@ void Document::set_hovered_node(Node* node)
 
 JS::NonnullGCPtr<HTMLCollection> Document::get_elements_by_name(String const& name)
 {
-    auto deprecated_name = name.to_deprecated_string();
+    auto deprecated_name = name.to_byte_string();
     return HTMLCollection::create(*this, HTMLCollection::Scope::Descendants, [deprecated_name](Element const& element) {
         return element.name() == deprecated_name;
     });
@@ -1349,7 +1349,7 @@ HTML::EnvironmentSettingsObject& Document::relevant_settings_object() const
 // https://dom.spec.whatwg.org/#dom-document-createelement
 WebIDL::ExceptionOr<JS::NonnullGCPtr<Element>> Document::create_element(String const& a_local_name, Variant<String, ElementCreationOptions> const& options)
 {
-    auto local_name = a_local_name.to_deprecated_string();
+    auto local_name = a_local_name.to_byte_string();
 
     // 1. If localName does not match the Name production, then throw an "InvalidCharacterError" DOMException.
     if (!is_valid_name(a_local_name))
@@ -1427,7 +1427,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<ProcessingInstruction>> Document::create_pr
     // FIXME: 2. If data contains the string "?>", then throw an "InvalidCharacterError" DOMException.
 
     // 3. Return a new ProcessingInstruction node, with target set to target, data set to data, and node document set to this.
-    return heap().allocate<ProcessingInstruction>(realm(), *this, data.to_deprecated_string(), target.to_deprecated_string());
+    return heap().allocate<ProcessingInstruction>(realm(), *this, data.to_byte_string(), target.to_byte_string());
 }
 
 JS::NonnullGCPtr<Range> Document::create_range()
@@ -1974,7 +1974,7 @@ void Document::completely_finish_loading()
 
 String Document::cookie(Cookie::Source source)
 {
-    return MUST(String::from_deprecated_string(page().client().page_did_request_cookie(m_url, source)));
+    return MUST(String::from_byte_string(page().client().page_did_request_cookie(m_url, source)));
 }
 
 void Document::set_cookie(StringView cookie_string, Cookie::Source source)
@@ -3021,7 +3021,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Attr>> Document::create_attribute(String co
 
     // 2. If this is an HTML document, then set localName to localName in ASCII lowercase.
     // 3. Return a new attribute whose local name is localName and node document is this.
-    auto deprecated_local_name = local_name.to_deprecated_string();
+    auto deprecated_local_name = local_name.to_byte_string();
     return Attr::create(*this, MUST(FlyString::from_deprecated_fly_string(is_html_document() ? deprecated_local_name.to_lowercase() : deprecated_local_name)));
 }
 
diff --git a/Userland/Libraries/LibWeb/DOM/DocumentLoading.cpp b/Userland/Libraries/LibWeb/DOM/DocumentLoading.cpp
index f85e321b81d..529e11887f3 100644
--- a/Userland/Libraries/LibWeb/DOM/DocumentLoading.cpp
+++ b/Userland/Libraries/LibWeb/DOM/DocumentLoading.cpp
@@ -88,7 +88,7 @@ static bool build_text_document(DOM::Document& document, ByteBuffer const& data)
     auto title_element = DOM::create_element(document, HTML::TagNames::title, Namespace::HTML).release_value_but_fixme_should_propagate_errors();
     MUST(head_element->append_child(title_element));
 
-    auto title_text = document.create_text_node(MUST(String::from_deprecated_string(document.url().basename())));
+    auto title_text = document.create_text_node(MUST(String::from_byte_string(document.url().basename())));
     MUST(title_element->append_child(title_text));
 
     auto body_element = DOM::create_element(document, HTML::TagNames::body, Namespace::HTML).release_value_but_fixme_should_propagate_errors();
@@ -137,7 +137,7 @@ static bool build_gemini_document(DOM::Document& document, ByteBuffer const& dat
 {
     StringView gemini_data { data };
     auto gemini_document = Gemini::Document::parse(gemini_data, document.url());
-    DeprecatedString html_data = gemini_document->render_to_html();
+    ByteString html_data = gemini_document->render_to_html();
 
     dbgln_if(GEMINI_DEBUG, "Gemini data:\n\"\"\"{}\"\"\"", gemini_data);
     dbgln_if(GEMINI_DEBUG, "Converted to HTML:\n\"\"\"{}\"\"\"", html_data);
diff --git a/Userland/Libraries/LibWeb/DOM/Element.cpp b/Userland/Libraries/LibWeb/DOM/Element.cpp
index df276a5f29a..c2a8a5c2102 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Element.cpp
@@ -120,27 +120,27 @@ Optional<String> Element::get_attribute(StringView name) const
     return attribute->value();
 }
 
-DeprecatedString Element::deprecated_get_attribute(StringView name) const
+ByteString Element::deprecated_get_attribute(StringView name) const
 {
     auto maybe_attribute = get_attribute(name);
     if (!maybe_attribute.has_value())
-        return DeprecatedString::empty();
+        return ByteString::empty();
 
-    return maybe_attribute->to_deprecated_string();
+    return maybe_attribute->to_byte_string();
 }
 
 // https://dom.spec.whatwg.org/#concept-element-attributes-get-value
-DeprecatedString Element::get_attribute_value(FlyString const& local_name, Optional<FlyString> const& namespace_) const
+ByteString Element::get_attribute_value(FlyString const& local_name, Optional<FlyString> const& namespace_) const
 {
     // 1. Let attr be the result of getting an attribute given namespace, localName, and element.
     auto const* attribute = m_attributes->get_attribute_ns(namespace_, local_name);
 
     // 2. If attr is null, then return the empty string.
     if (!attribute)
-        return DeprecatedString::empty();
+        return ByteString::empty();
 
     // 3. Return attr’s value.
-    return attribute->value().to_deprecated_string();
+    return attribute->value().to_byte_string();
 }
 
 // https://dom.spec.whatwg.org/#dom-element-getattributenode
@@ -247,7 +247,7 @@ void Element::append_attribute(Attr& attribute)
 }
 
 // https://dom.spec.whatwg.org/#concept-element-attributes-set-value
-void Element::set_attribute_value(FlyString const& local_name, DeprecatedString const& value, Optional<FlyString> const& prefix, Optional<FlyString> const& namespace_)
+void Element::set_attribute_value(FlyString const& local_name, ByteString const& value, Optional<FlyString> const& prefix, Optional<FlyString> const& namespace_)
 {
     // 1. Let attribute be the result of getting an attribute given namespace, localName, and element.
     auto* attribute = m_attributes->get_attribute_ns(namespace_, local_name);
@@ -258,14 +258,14 @@ void Element::set_attribute_value(FlyString const& local_name, DeprecatedString
     if (!attribute) {
         QualifiedName name { local_name, prefix, namespace_ };
 
-        auto new_attribute = Attr::create(document(), move(name), MUST(String::from_deprecated_string(value)));
+        auto new_attribute = Attr::create(document(), move(name), MUST(String::from_byte_string(value)));
         m_attributes->append_attribute(new_attribute);
 
         return;
     }
 
     // 3. Change attribute to value.
-    attribute->change_attribute(MUST(String::from_deprecated_string(value)));
+    attribute->change_attribute(MUST(String::from_byte_string(value)));
 }
 
 // https://dom.spec.whatwg.org/#dom-element-setattributenode
@@ -1457,7 +1457,7 @@ WebIDL::ExceptionOr<void> Element::insert_adjacent_html(String const& position,
 }
 
 // https://dom.spec.whatwg.org/#insert-adjacent
-WebIDL::ExceptionOr<JS::GCPtr<Node>> Element::insert_adjacent(DeprecatedString const& where, JS::NonnullGCPtr<Node> node)
+WebIDL::ExceptionOr<JS::GCPtr<Node>> Element::insert_adjacent(ByteString const& where, JS::NonnullGCPtr<Node> node)
 {
     // To insert adjacent, given an element element, string where, and a node node, run the steps associated with the first ASCII case-insensitive match for where:
     if (Infra::is_ascii_case_insensitive_match(where, "beforebegin"sv)) {
@@ -1501,7 +1501,7 @@ WebIDL::ExceptionOr<JS::GCPtr<Node>> Element::insert_adjacent(DeprecatedString c
 WebIDL::ExceptionOr<JS::GCPtr<Element>> Element::insert_adjacent_element(String const& where, JS::NonnullGCPtr<Element> element)
 {
     // The insertAdjacentElement(where, element) method steps are to return the result of running insert adjacent, give this, where, and element.
-    auto returned_node = TRY(insert_adjacent(where.to_deprecated_string(), move(element)));
+    auto returned_node = TRY(insert_adjacent(where.to_byte_string(), move(element)));
     if (!returned_node)
         return JS::GCPtr<Element> { nullptr };
     return JS::GCPtr<Element> { verify_cast<Element>(*returned_node) };
@@ -1515,7 +1515,7 @@ WebIDL::ExceptionOr<void> Element::insert_adjacent_text(String const& where, Str
 
     // 2. Run insert adjacent, given this, where, and text.
     // Spec Note: This method returns nothing because it existed before we had a chance to design it.
-    (void)TRY(insert_adjacent(where.to_deprecated_string(), text));
+    (void)TRY(insert_adjacent(where.to_byte_string(), text));
     return {};
 }
 
@@ -2019,10 +2019,10 @@ void Element::for_each_attribute(Function<void(Attr const&)> callback) const
         callback(*m_attributes->item(i));
 }
 
-void Element::for_each_attribute(Function<void(FlyString const&, DeprecatedString const&)> callback) const
+void Element::for_each_attribute(Function<void(FlyString const&, ByteString const&)> callback) const
 {
     for_each_attribute([&callback](Attr const& attr) {
-        callback(attr.name(), attr.value().to_deprecated_string());
+        callback(attr.name(), attr.value().to_byte_string());
     });
 }
 
diff --git a/Userland/Libraries/LibWeb/DOM/Element.h b/Userland/Libraries/LibWeb/DOM/Element.h
index 6105ccdd2fc..8b0a6d0f873 100644
--- a/Userland/Libraries/LibWeb/DOM/Element.h
+++ b/Userland/Libraries/LibWeb/DOM/Element.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibWeb/ARIA/ARIAMixin.h>
 #include <LibWeb/Bindings/ElementPrototype.h>
 #include <LibWeb/Bindings/Intrinsics.h>
@@ -82,7 +82,7 @@ public:
 
     // NOTE: This is for the JS bindings
     FlyString const& tag_name() const { return html_uppercased_qualified_name(); }
-    DeprecatedString deprecated_tag_name() const { return html_uppercased_qualified_name().to_deprecated_fly_string(); }
+    ByteString deprecated_tag_name() const { return html_uppercased_qualified_name().to_deprecated_fly_string(); }
 
     Optional<FlyString> const& prefix() const { return m_qualified_name.prefix(); }
 
@@ -97,19 +97,19 @@ public:
     bool has_attributes() const;
 
     // FIXME: This should be taking a 'FlyString const&'
-    DeprecatedString deprecated_attribute(StringView name) const { return deprecated_get_attribute(name); }
+    ByteString deprecated_attribute(StringView name) const { return deprecated_get_attribute(name); }
     Optional<String> attribute(StringView name) const { return get_attribute(name); }
 
     // FIXME: This should be taking a 'FlyString const&' / 'Optional<FlyString> const&'
     Optional<String> get_attribute(StringView name) const;
-    DeprecatedString deprecated_get_attribute(StringView name) const;
-    DeprecatedString get_attribute_value(FlyString const& local_name, Optional<FlyString> const& namespace_ = {}) const;
+    ByteString deprecated_get_attribute(StringView name) const;
+    ByteString get_attribute_value(FlyString const& local_name, Optional<FlyString> const& namespace_ = {}) const;
 
     WebIDL::ExceptionOr<void> set_attribute(FlyString const& name, String const& value);
 
     // FIXME: This should be taking an Optional<FlyString>
     WebIDL::ExceptionOr<void> set_attribute_ns(Optional<String> const& namespace_, FlyString const& qualified_name, FlyString const& value);
-    void set_attribute_value(FlyString const& local_name, DeprecatedString const& value, Optional<FlyString> const& prefix = {}, Optional<FlyString> const& namespace_ = {});
+    void set_attribute_value(FlyString const& local_name, ByteString const& value, Optional<FlyString> const& prefix = {}, Optional<FlyString> const& namespace_ = {});
     WebIDL::ExceptionOr<JS::GCPtr<Attr>> set_attribute_node(Attr&);
     WebIDL::ExceptionOr<JS::GCPtr<Attr>> set_attribute_node_ns(Attr&);
 
@@ -140,7 +140,7 @@ public:
 
     void for_each_attribute(Function<void(Attr const&)>) const;
 
-    void for_each_attribute(Function<void(FlyString const&, DeprecatedString const&)>) const;
+    void for_each_attribute(Function<void(FlyString const&, ByteString const&)>) const;
 
     bool has_class(FlyString const&, CaseSensitivity = CaseSensitivity::CaseSensitive) const;
     Vector<FlyString> const& class_names() const { return m_classes; }
@@ -179,7 +179,7 @@ public:
     Layout::NodeWithStyle* layout_node();
     Layout::NodeWithStyle const* layout_node() const;
 
-    DeprecatedString name() const { return deprecated_attribute(HTML::AttributeNames::name); }
+    ByteString name() const { return deprecated_attribute(HTML::AttributeNames::name); }
 
     CSS::StyleProperties* computed_css_values() { return m_computed_css_values.ptr(); }
     CSS::StyleProperties const* computed_css_values() const { return m_computed_css_values.ptr(); }
@@ -395,7 +395,7 @@ private:
 
     void invalidate_style_after_attribute_change(FlyString const& attribute_name);
 
-    WebIDL::ExceptionOr<JS::GCPtr<Node>> insert_adjacent(DeprecatedString const& where, JS::NonnullGCPtr<Node> node);
+    WebIDL::ExceptionOr<JS::GCPtr<Node>> insert_adjacent(ByteString const& where, JS::NonnullGCPtr<Node> node);
 
     void enqueue_an_element_on_the_appropriate_element_queue();
 
diff --git a/Userland/Libraries/LibWeb/DOM/EventTarget.cpp b/Userland/Libraries/LibWeb/DOM/EventTarget.cpp
index 48d82057284..11d709b0d5b 100644
--- a/Userland/Libraries/LibWeb/DOM/EventTarget.cpp
+++ b/Userland/Libraries/LibWeb/DOM/EventTarget.cpp
@@ -364,7 +364,7 @@ WebIDL::CallbackType* EventTarget::get_current_value_of_event_handler(FlyString
     auto& event_handler = event_handler_iterator->value;
 
     // 3. If eventHandler's value is an internal raw uncompiled handler, then:
-    if (event_handler->value.has<DeprecatedString>()) {
+    if (event_handler->value.has<ByteString>()) {
         // 1. If eventTarget is an element, then let element be eventTarget, and document be element's node document.
         //    Otherwise, eventTarget is a Window object, let element be null, and document be eventTarget's associated Document.
         JS::GCPtr<Element> element;
@@ -387,7 +387,7 @@ WebIDL::CallbackType* EventTarget::get_current_value_of_event_handler(FlyString
             return nullptr;
 
         // 3. Let body be the uncompiled script body in eventHandler's value.
-        auto& body = event_handler->value.get<DeprecatedString>();
+        auto& body = event_handler->value.get<ByteString>();
 
         // FIXME: 4. Let location be the location where the script body originated, as given by eventHandler's value.
 
@@ -418,7 +418,7 @@ WebIDL::CallbackType* EventTarget::get_current_value_of_event_handler(FlyString
             builder.appendff("function {}(event) {{\n{}\n}}", name, body);
         }
 
-        auto source_text = builder.to_deprecated_string();
+        auto source_text = builder.to_byte_string();
 
         auto parser = JS::Parser(JS::Lexer(source_text));
 
@@ -486,7 +486,7 @@ WebIDL::CallbackType* EventTarget::get_current_value_of_event_handler(FlyString
 
         //  6. Return scope. (NOTE: Not necessary)
 
-        auto function = JS::ECMAScriptFunctionObject::create(realm, name.to_deprecated_fly_string(), builder.to_deprecated_string(), program->body(), program->parameters(), program->function_length(), program->local_variables_names(), scope, nullptr, JS::FunctionKind::Normal, program->is_strict_mode(), program->might_need_arguments_object(), is_arrow_function);
+        auto function = JS::ECMAScriptFunctionObject::create(realm, name.to_deprecated_fly_string(), builder.to_byte_string(), program->body(), program->parameters(), program->function_length(), program->local_variables_names(), scope, nullptr, JS::FunctionKind::Normal, program->is_strict_mode(), program->might_need_arguments_object(), is_arrow_function);
 
         // 10. Remove settings object's realm execution context from the JavaScript execution context stack.
         VERIFY(vm.execution_context_stack().last() == &settings_object.realm_execution_context());
@@ -747,7 +747,7 @@ void EventTarget::element_event_handler_attribute_changed(FlyString const& local
     // NOTE: See the optimization comments in set_event_handler_attribute.
 
     if (event_handler_iterator == handler_map.end()) {
-        auto new_event_handler = heap().allocate_without_realm<HTML::EventHandler>(value->to_deprecated_string());
+        auto new_event_handler = heap().allocate_without_realm<HTML::EventHandler>(value->to_byte_string());
 
         //  6. Activate an event handler given eventTarget and name.
         event_target->activate_event_handler(local_name, *new_event_handler);
@@ -759,7 +759,7 @@ void EventTarget::element_event_handler_attribute_changed(FlyString const& local
     auto& event_handler = event_handler_iterator->value;
 
     //  6. Activate an event handler given eventTarget and name.
-    event_handler->value = value->to_deprecated_string();
+    event_handler->value = value->to_byte_string();
     event_target->activate_event_handler(local_name, *event_handler);
 }
 
diff --git a/Userland/Libraries/LibWeb/DOM/NamedNodeMap.cpp b/Userland/Libraries/LibWeb/DOM/NamedNodeMap.cpp
index 46b83d7c68a..9c5ea50f610 100644
--- a/Userland/Libraries/LibWeb/DOM/NamedNodeMap.cpp
+++ b/Userland/Libraries/LibWeb/DOM/NamedNodeMap.cpp
@@ -233,7 +233,7 @@ WebIDL::ExceptionOr<JS::GCPtr<Attr>> NamedNodeMap::set_attribute(Attr& attribute
 
     // 2. Let oldAttr be the result of getting an attribute given attr’s namespace, attr’s local name, and element.
     size_t old_attribute_index = 0;
-    DeprecatedString deprecated_namespace_uri;
+    ByteString deprecated_namespace_uri;
     if (attribute.namespace_uri().has_value())
         deprecated_namespace_uri = attribute.namespace_uri().value().to_deprecated_fly_string();
 
diff --git a/Userland/Libraries/LibWeb/DOM/NamedNodeMap.h b/Userland/Libraries/LibWeb/DOM/NamedNodeMap.h
index b5157ca7c3e..747231f5ddf 100644
--- a/Userland/Libraries/LibWeb/DOM/NamedNodeMap.h
+++ b/Userland/Libraries/LibWeb/DOM/NamedNodeMap.h
@@ -9,7 +9,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringView.h>
 #include <LibWeb/Bindings/LegacyPlatformObject.h>
 #include <LibWeb/Forward.h>
diff --git a/Userland/Libraries/LibWeb/DOM/Node.cpp b/Userland/Libraries/LibWeb/DOM/Node.cpp
index fc041b8a89d..0a908a165d8 100644
--- a/Userland/Libraries/LibWeb/DOM/Node.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Node.cpp
@@ -819,7 +819,7 @@ JS::NonnullGCPtr<Node> Node::clone_node(Document* document, bool clone_children)
         element.for_each_attribute([&](auto& name, auto& value) {
             // 1. Let copyAttribute be a clone of attribute.
             // 2. Append copyAttribute to copy.
-            MUST(element_copy->set_attribute(name, MUST(String::from_deprecated_string(value))));
+            MUST(element_copy->set_attribute(name, MUST(String::from_byte_string(value))));
         });
         copy = move(element_copy);
 
@@ -872,7 +872,7 @@ JS::NonnullGCPtr<Node> Node::clone_node(Document* document, bool clone_children)
         auto processing_instruction = verify_cast<ProcessingInstruction>(this);
 
         // Set copy’s target and data to those of node.
-        auto processing_instruction_copy = heap().allocate<ProcessingInstruction>(realm(), *document, processing_instruction->data().to_deprecated_string(), processing_instruction->target());
+        auto processing_instruction_copy = heap().allocate<ProcessingInstruction>(realm(), *document, processing_instruction->data().to_byte_string(), processing_instruction->target());
         copy = processing_instruction_copy;
     }
     // Otherwise, Do nothing.
@@ -1783,8 +1783,8 @@ ErrorOr<String> Node::name_or_description(NameOrDescription target, Document con
         //   process its IDREFs in the order they occur:
         auto aria_labelled_by = element->aria_labelled_by();
         auto aria_described_by = element->aria_described_by();
-        if ((target == NameOrDescription::Name && aria_labelled_by.has_value() && Node::first_valid_id(aria_labelled_by->to_deprecated_string(), document).has_value())
-            || (target == NameOrDescription::Description && aria_described_by.has_value() && Node::first_valid_id(aria_described_by->to_deprecated_string(), document).has_value())) {
+        if ((target == NameOrDescription::Name && aria_labelled_by.has_value() && Node::first_valid_id(aria_labelled_by->to_byte_string(), document).has_value())
+            || (target == NameOrDescription::Description && aria_described_by.has_value() && Node::first_valid_id(aria_described_by->to_byte_string(), document).has_value())) {
 
             // i. Set the accumulated text to the empty string.
             total_accumulated_text.clear();
diff --git a/Userland/Libraries/LibWeb/DOM/NodeOperations.cpp b/Userland/Libraries/LibWeb/DOM/NodeOperations.cpp
index a18ff863ac9..fb67b1c70fa 100644
--- a/Userland/Libraries/LibWeb/DOM/NodeOperations.cpp
+++ b/Userland/Libraries/LibWeb/DOM/NodeOperations.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <LibWeb/DOM/Document.h>
 #include <LibWeb/DOM/DocumentFragment.h>
diff --git a/Userland/Libraries/LibWeb/DOM/ProcessingInstruction.cpp b/Userland/Libraries/LibWeb/DOM/ProcessingInstruction.cpp
index b50286b6255..82512f64ab2 100644
--- a/Userland/Libraries/LibWeb/DOM/ProcessingInstruction.cpp
+++ b/Userland/Libraries/LibWeb/DOM/ProcessingInstruction.cpp
@@ -13,8 +13,8 @@ namespace Web::DOM {
 
 JS_DEFINE_ALLOCATOR(ProcessingInstruction);
 
-ProcessingInstruction::ProcessingInstruction(Document& document, DeprecatedString const& data, DeprecatedString const& target)
-    : CharacterData(document, NodeType::PROCESSING_INSTRUCTION_NODE, MUST(String::from_deprecated_string(data)))
+ProcessingInstruction::ProcessingInstruction(Document& document, ByteString const& data, ByteString const& target)
+    : CharacterData(document, NodeType::PROCESSING_INSTRUCTION_NODE, MUST(String::from_byte_string(data)))
     , m_target(target)
 {
 }
diff --git a/Userland/Libraries/LibWeb/DOM/ProcessingInstruction.h b/Userland/Libraries/LibWeb/DOM/ProcessingInstruction.h
index 859045c8485..ba2dfe6103e 100644
--- a/Userland/Libraries/LibWeb/DOM/ProcessingInstruction.h
+++ b/Userland/Libraries/LibWeb/DOM/ProcessingInstruction.h
@@ -19,14 +19,14 @@ public:
 
     virtual FlyString node_name() const override { return MUST(FlyString::from_deprecated_fly_string(m_target)); }
 
-    DeprecatedString const& target() const { return m_target; }
+    ByteString const& target() const { return m_target; }
 
 private:
-    ProcessingInstruction(Document&, DeprecatedString const& data, DeprecatedString const& target);
+    ProcessingInstruction(Document&, ByteString const& data, ByteString const& target);
 
     virtual void initialize(JS::Realm&) override;
 
-    DeprecatedString m_target;
+    ByteString m_target;
 };
 
 template<>
diff --git a/Userland/Libraries/LibWeb/DOM/Range.cpp b/Userland/Libraries/LibWeb/DOM/Range.cpp
index cbb1e86e3d0..1a35748bf25 100644
--- a/Userland/Libraries/LibWeb/DOM/Range.cpp
+++ b/Userland/Libraries/LibWeb/DOM/Range.cpp
@@ -1187,7 +1187,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<DocumentFragment>> Range::create_contextual
     }
 
     // 3. Let fragment node be the result of invoking the fragment parsing algorithm with fragment as markup, and element as the context element.
-    auto fragment_node = TRY(DOMParsing::parse_fragment(fragment.to_deprecated_string(), *element));
+    auto fragment_node = TRY(DOMParsing::parse_fragment(fragment.to_byte_string(), *element));
 
     // 4. Unmark all scripts in fragment node as "already started" and as "parser-inserted".
     fragment_node->for_each_in_subtree_of_type<HTML::HTMLScriptElement>([&](HTML::HTMLScriptElement& script_element) {
diff --git a/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp b/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
index 1628f6666ba..802ca333626 100644
--- a/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
+++ b/Userland/Libraries/LibWeb/Fetch/Fetching/Fetching.cpp
@@ -1424,7 +1424,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_network_or_cache_fet
                     // FIXME: Getting to the page client reliably is way too complicated, and going via the document won't work in workers.
                     auto document = Bindings::host_defined_environment_settings_object(realm).responsible_document();
                     if (!document)
-                        return DeprecatedString::empty();
+                        return ByteString::empty();
                     return document->page().client().page_did_request_cookie(http_request->current_url(), Cookie::Source::Http);
                 })();
 
@@ -1604,8 +1604,8 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> http_network_or_cache_fet
                 // FIXME: 2. Let username and password be the result of prompting the end user for a username and password,
                 //           respectively, in request’s window.
                 dbgln("Fetch: Username/password prompt is not implemented, using empty strings. This request will probably fail.");
-                auto username = DeprecatedString::empty();
-                auto password = DeprecatedString::empty();
+                auto username = ByteString::empty();
+                auto password = ByteString::empty();
 
                 // 3. Set the username given request’s current URL and username.
                 MUST(request->current_url().set_username(username));
@@ -1729,9 +1729,9 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<PendingResponse>> nonstandard_resource_load
     LoadRequest load_request;
     load_request.set_url(request->current_url());
     load_request.set_page(page);
-    load_request.set_method(DeprecatedString::copy(request->method()));
+    load_request.set_method(ByteString::copy(request->method()));
     for (auto const& header : *request->header_list())
-        load_request.set_header(DeprecatedString::copy(header.name), DeprecatedString::copy(header.value));
+        load_request.set_header(ByteString::copy(header.name), ByteString::copy(header.value));
     if (auto const* body = request->body().get_pointer<JS::NonnullGCPtr<Infrastructure::Body>>()) {
         TRY((*body)->source().visit(
             [&](ByteBuffer const& byte_buffer) -> WebIDL::ExceptionOr<void> {
diff --git a/Userland/Libraries/LibWeb/Fetch/Infrastructure/HTTP/Requests.cpp b/Userland/Libraries/LibWeb/Fetch/Infrastructure/HTTP/Requests.cpp
index 36bcb63349f..67f55c912e7 100644
--- a/Userland/Libraries/LibWeb/Fetch/Infrastructure/HTTP/Requests.cpp
+++ b/Userland/Libraries/LibWeb/Fetch/Infrastructure/HTTP/Requests.cpp
@@ -196,7 +196,7 @@ ErrorOr<String> Request::serialize_origin() const
         return "null"_string;
 
     // 2. Return request’s origin, serialized.
-    return String::from_deprecated_string(m_origin.get<HTML::Origin>().serialize());
+    return String::from_byte_string(m_origin.get<HTML::Origin>().serialize());
 }
 
 // https://fetch.spec.whatwg.org/#byte-serializing-a-request-origin
diff --git a/Userland/Libraries/LibWeb/Fetch/Request.cpp b/Userland/Libraries/LibWeb/Fetch/Request.cpp
index 85725d799d2..8bb7e16d8c9 100644
--- a/Userland/Libraries/LibWeb/Fetch/Request.cpp
+++ b/Userland/Libraries/LibWeb/Fetch/Request.cpp
@@ -514,7 +514,7 @@ WebIDL::ExceptionOr<String> Request::url() const
     auto& vm = this->vm();
 
     // The url getter steps are to return this’s request’s URL, serialized.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_request->url().serialize()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(m_request->url().serialize()));
 }
 
 // https://fetch.spec.whatwg.org/#dom-request-headers
@@ -550,7 +550,7 @@ WebIDL::ExceptionOr<String> Request::referrer() const
         },
         [&](AK::URL const& url) -> WebIDL::ExceptionOr<String> {
             // 3. Return this’s request’s referrer, serialized.
-            return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(url.serialize()));
+            return TRY_OR_THROW_OOM(vm, String::from_byte_string(url.serialize()));
         });
 }
 
diff --git a/Userland/Libraries/LibWeb/Fetch/Response.cpp b/Userland/Libraries/LibWeb/Fetch/Response.cpp
index 68e5de352b4..775409aff77 100644
--- a/Userland/Libraries/LibWeb/Fetch/Response.cpp
+++ b/Userland/Libraries/LibWeb/Fetch/Response.cpp
@@ -239,7 +239,7 @@ WebIDL::ExceptionOr<String> Response::url() const
     // The url getter steps are to return the empty string if this’s response’s URL is null; otherwise this’s response’s URL, serialized with exclude fragment set to true.
     return !m_response->url().has_value()
         ? String {}
-        : TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_response->url()->serialize(AK::URL::ExcludeFragment::Yes)));
+        : TRY_OR_THROW_OOM(vm, String::from_byte_string(m_response->url()->serialize(AK::URL::ExcludeFragment::Yes)));
 }
 
 // https://fetch.spec.whatwg.org/#dom-response-redirected
diff --git a/Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp b/Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp
index eb54fa8fd7e..26330f5a2a0 100644
--- a/Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp
+++ b/Userland/Libraries/LibWeb/HTML/BrowsingContext.cpp
@@ -226,7 +226,7 @@ WebIDL::ExceptionOr<BrowsingContext::BrowsingContextAndDocument> BrowsingContext
     // 15. If creator is non-null, then:
     if (creator) {
         // 1. Set document's referrer to the serialization of creator's URL.
-        document->set_referrer(MUST(String::from_deprecated_string(creator->url().serialize())));
+        document->set_referrer(MUST(String::from_byte_string(creator->url().serialize())));
 
         // FIXME: 2. Set document's policy container to a clone of creator's policy container.
 
@@ -412,7 +412,7 @@ void BrowsingContext::set_cursor_position(JS::NonnullGCPtr<DOM::Position> positi
     reset_cursor_blink_cycle();
 }
 
-static DeprecatedString visible_text_in_range(DOM::Range const& range)
+static ByteString visible_text_in_range(DOM::Range const& range)
 {
     // NOTE: This is an adaption of Range stringification, but we skip over DOM nodes that don't have a corresponding layout node.
     StringBuilder builder;
@@ -420,7 +420,7 @@ static DeprecatedString visible_text_in_range(DOM::Range const& range)
     if (range.start_container() == range.end_container() && is<DOM::Text>(*range.start_container())) {
         if (!range.start_container()->layout_node())
             return ""sv;
-        return MUST(static_cast<DOM::Text const&>(*range.start_container()).data().substring_from_byte_offset(range.start_offset(), range.end_offset() - range.start_offset())).to_deprecated_string();
+        return MUST(static_cast<DOM::Text const&>(*range.start_container()).data().substring_from_byte_offset(range.start_offset(), range.end_offset() - range.start_offset())).to_byte_string();
     }
 
     if (is<DOM::Text>(*range.start_container()) && range.start_container()->layout_node())
@@ -434,10 +434,10 @@ static DeprecatedString visible_text_in_range(DOM::Range const& range)
     if (is<DOM::Text>(*range.end_container()) && range.end_container()->layout_node())
         builder.append(static_cast<DOM::Text const&>(*range.end_container()).data().bytes_as_string_view().substring_view(0, range.end_offset()));
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString BrowsingContext::selected_text() const
+ByteString BrowsingContext::selected_text() const
 {
     auto* document = active_document();
     if (!document)
diff --git a/Userland/Libraries/LibWeb/HTML/BrowsingContext.h b/Userland/Libraries/LibWeb/HTML/BrowsingContext.h
index 6017aa6e182..f0ef53c3a0a 100644
--- a/Userland/Libraries/LibWeb/HTML/BrowsingContext.h
+++ b/Userland/Libraries/LibWeb/HTML/BrowsingContext.h
@@ -151,7 +151,7 @@ public:
 
     bool cursor_blink_state() const { return m_cursor_blink_state; }
 
-    DeprecatedString selected_text() const;
+    ByteString selected_text() const;
     void select_all();
 
     void did_edit(Badge<EditEventHandler>);
@@ -222,7 +222,7 @@ private:
     RefPtr<Core::Timer> m_cursor_blink_timer;
     bool m_cursor_blink_state { false };
 
-    DeprecatedString m_name;
+    ByteString m_name;
 
     // https://html.spec.whatwg.org/multipage/browsers.html#tlbc-group
     JS::GCPtr<BrowsingContextGroup> m_group;
diff --git a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasDrawPath.h b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasDrawPath.h
index eba6d8daca5..cefa427ec0e 100644
--- a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasDrawPath.h
+++ b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasDrawPath.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibWeb/HTML/Path2D.h>
 
 namespace Web::HTML {
diff --git a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasState.h b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasState.h
index e5d460ffc30..88ee2565884 100644
--- a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasState.h
+++ b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasState.h
@@ -58,7 +58,7 @@ public:
         {
             return m_fill_or_stroke_style.visit(
                 [&](Gfx::Color color) -> JsFillOrStrokeStyle {
-                    return MUST(String::from_deprecated_string(color.to_deprecated_string()));
+                    return MUST(String::from_byte_string(color.to_byte_string()));
                 },
                 [&](auto handle) -> JsFillOrStrokeStyle {
                     return handle;
diff --git a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasText.h b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasText.h
index 220b5b9c93d..262bca9f275 100644
--- a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasText.h
+++ b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasText.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <LibWeb/HTML/TextMetrics.h>
 
diff --git a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasTextDrawingStyles.h b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasTextDrawingStyles.h
index 56b01004403..6e945a82c9f 100644
--- a/Userland/Libraries/LibWeb/HTML/Canvas/CanvasTextDrawingStyles.h
+++ b/Userland/Libraries/LibWeb/HTML/Canvas/CanvasTextDrawingStyles.h
@@ -20,7 +20,7 @@ class CanvasTextDrawingStyles {
 public:
     ~CanvasTextDrawingStyles() = default;
 
-    DeprecatedString font() const
+    ByteString font() const
     {
         // When font style value is empty return default string
         if (!my_drawing_state().font_style_value) {
@@ -33,7 +33,7 @@ public:
         auto font_weight = font_style_value.longhand(CSS::PropertyID::FontWeight);
         auto font_size = font_style_value.longhand(CSS::PropertyID::FontSize);
         auto font_family = font_style_value.longhand(CSS::PropertyID::FontFamily);
-        return DeprecatedString::formatted("{} {} {} {}", font_style->to_string(), font_weight->to_string(), font_size->to_string(), font_family->to_string());
+        return ByteString::formatted("{} {} {} {}", font_style->to_string(), font_weight->to_string(), font_size->to_string(), font_family->to_string());
     }
 
     void set_font(StringView font)
diff --git a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp
index 2a632daa62f..54d8e47033c 100644
--- a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp
+++ b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.cpp
@@ -440,7 +440,7 @@ RefPtr<Gfx::Font const> CanvasRenderingContext2D::current_font()
 }
 
 // https://html.spec.whatwg.org/multipage/canvas.html#text-preparation-algorithm
-CanvasRenderingContext2D::PreparedText CanvasRenderingContext2D::prepare_text(DeprecatedString const& text, float max_width)
+CanvasRenderingContext2D::PreparedText CanvasRenderingContext2D::prepare_text(ByteString const& text, float max_width)
 {
     // 1. If maxWidth was provided but is less than or equal to zero or equal to NaN, then return an empty array.
     if (max_width <= 0 || max_width != max_width) {
@@ -452,7 +452,7 @@ CanvasRenderingContext2D::PreparedText CanvasRenderingContext2D::prepare_text(De
     for (auto c : text) {
         builder.append(Infra::is_ascii_whitespace(c) ? ' ' : c);
     }
-    auto replaced_text = builder.to_deprecated_string();
+    auto replaced_text = builder.to_byte_string();
 
     // 3. Let font be the current font of target, as given by that object's font attribute.
     auto font = current_font();
diff --git a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.h b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.h
index bbffcf841cc..cce9f5a3f43 100644
--- a/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.h
+++ b/Userland/Libraries/LibWeb/HTML/CanvasRenderingContext2D.h
@@ -138,7 +138,7 @@ private:
 
     RefPtr<Gfx::Font const> current_font();
 
-    PreparedText prepare_text(DeprecatedString const& text, float max_width = INFINITY);
+    PreparedText prepare_text(ByteString const& text, float max_width = INFINITY);
 
     Gfx::Painter* painter();
     Optional<Gfx::AntiAliasingPainter> antialiased_painter();
diff --git a/Userland/Libraries/LibWeb/HTML/CrossOrigin/CrossOriginPropertyDescriptorMap.h b/Userland/Libraries/LibWeb/HTML/CrossOrigin/CrossOriginPropertyDescriptorMap.h
index e08c05072a4..be1a4c0a7ca 100644
--- a/Userland/Libraries/LibWeb/HTML/CrossOrigin/CrossOriginPropertyDescriptorMap.h
+++ b/Userland/Libraries/LibWeb/HTML/CrossOrigin/CrossOriginPropertyDescriptorMap.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/Optional.h>
 #include <AK/Traits.h>
@@ -16,7 +16,7 @@
 namespace Web::HTML {
 
 struct CrossOriginProperty {
-    DeprecatedString property;
+    ByteString property;
     Optional<bool> needs_get {};
     Optional<bool> needs_set {};
 };
diff --git a/Userland/Libraries/LibWeb/HTML/DOMStringMap.cpp b/Userland/Libraries/LibWeb/HTML/DOMStringMap.cpp
index e3c2ce426dd..01e158fd6f4 100644
--- a/Userland/Libraries/LibWeb/HTML/DOMStringMap.cpp
+++ b/Userland/Libraries/LibWeb/HTML/DOMStringMap.cpp
@@ -82,7 +82,7 @@ Vector<DOMStringMap::NameValuePair> DOMStringMap::get_name_value_pairs() const
             builder.append(current_character);
         }
 
-        list.append({ MUST(builder.to_string()), MUST(String::from_deprecated_string(value)) });
+        list.append({ MUST(builder.to_string()), MUST(String::from_byte_string(value)) });
     });
 
     // 4. Return list.
@@ -190,7 +190,7 @@ WebIDL::ExceptionOr<Bindings::LegacyPlatformObject::DidDeletionFail> DOMStringMa
     }
 
     // Remove an attribute by name given name and the DOMStringMap's associated element.
-    auto data_name = builder.to_deprecated_string();
+    auto data_name = builder.to_byte_string();
     m_associated_element->remove_attribute(data_name);
 
     // The spec doesn't have the step. This indicates that the deletion was successful.
diff --git a/Userland/Libraries/LibWeb/HTML/Dates.cpp b/Userland/Libraries/LibWeb/HTML/Dates.cpp
index 2d44e5b9cab..4d3ec37d07c 100644
--- a/Userland/Libraries/LibWeb/HTML/Dates.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Dates.cpp
@@ -111,7 +111,7 @@ bool is_valid_date_string(StringView value)
     if (parts.size() != 3)
         return false;
 
-    if (!is_valid_month_string(DeprecatedString::formatted("{}-{}", parts[0], parts[1])))
+    if (!is_valid_month_string(ByteString::formatted("{}-{}", parts[0], parts[1])))
         return false;
 
     if (parts[2].length() != 2)
diff --git a/Userland/Libraries/LibWeb/HTML/EventHandler.cpp b/Userland/Libraries/LibWeb/HTML/EventHandler.cpp
index bcc31d6cce2..994bd6ccb4e 100644
--- a/Userland/Libraries/LibWeb/HTML/EventHandler.cpp
+++ b/Userland/Libraries/LibWeb/HTML/EventHandler.cpp
@@ -11,7 +11,7 @@ namespace Web::HTML {
 
 JS_DEFINE_ALLOCATOR(EventHandler);
 
-EventHandler::EventHandler(DeprecatedString s)
+EventHandler::EventHandler(ByteString s)
     : value(move(s))
 {
 }
diff --git a/Userland/Libraries/LibWeb/HTML/EventHandler.h b/Userland/Libraries/LibWeb/HTML/EventHandler.h
index 9e7374386e8..5319809bf6c 100644
--- a/Userland/Libraries/LibWeb/HTML/EventHandler.h
+++ b/Userland/Libraries/LibWeb/HTML/EventHandler.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Variant.h>
 #include <LibJS/Heap/Cell.h>
 #include <LibJS/Heap/CellAllocator.h>
@@ -19,7 +19,7 @@ class EventHandler final : public JS::Cell {
     JS_DECLARE_ALLOCATOR(EventHandler);
 
 public:
-    explicit EventHandler(DeprecatedString);
+    explicit EventHandler(ByteString);
     explicit EventHandler(WebIDL::CallbackType&);
 
     // Either uncompiled source code or a callback.
@@ -27,7 +27,7 @@ public:
     // NOTE: This does not contain Empty as part of the optimization of not allocating all event handler attributes up front.
     // FIXME: The string should actually be an "internal raw uncompiled handler" struct. This struct is just the uncompiled source code plus a source location for reporting parse errors.
     //        https://html.spec.whatwg.org/multipage/webappapis.html#internal-raw-uncompiled-handler
-    Variant<DeprecatedString, JS::GCPtr<WebIDL::CallbackType>> value;
+    Variant<ByteString, JS::GCPtr<WebIDL::CallbackType>> value;
 
     // https://html.spec.whatwg.org/multipage/webappapis.html#event-handler-listener
     JS::GCPtr<DOM::DOMEventListener> listener;
diff --git a/Userland/Libraries/LibWeb/HTML/Focus.cpp b/Userland/Libraries/LibWeb/HTML/Focus.cpp
index 0b9b6e6aadf..12e1d7ef096 100644
--- a/Userland/Libraries/LibWeb/HTML/Focus.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Focus.cpp
@@ -170,7 +170,7 @@ static Vector<JS::Handle<DOM::Node>> focus_chain(DOM::Node* subject)
 
 // https://html.spec.whatwg.org/multipage/interaction.html#focusing-steps
 // FIXME: This should accept more types.
-void run_focusing_steps(DOM::Node* new_focus_target, DOM::Node* fallback_target, [[maybe_unused]] Optional<DeprecatedString> focus_trigger)
+void run_focusing_steps(DOM::Node* new_focus_target, DOM::Node* fallback_target, [[maybe_unused]] Optional<ByteString> focus_trigger)
 {
     // FIXME: 1. If new focus target is not a focusable area, then set new focus target
     //           to the result of getting the focusable area for new focus target,
diff --git a/Userland/Libraries/LibWeb/HTML/Focus.h b/Userland/Libraries/LibWeb/HTML/Focus.h
index 111d2ffdc19..03ab002b947 100644
--- a/Userland/Libraries/LibWeb/HTML/Focus.h
+++ b/Userland/Libraries/LibWeb/HTML/Focus.h
@@ -6,13 +6,13 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <LibWeb/Forward.h>
 
 namespace Web::HTML {
 
-void run_focusing_steps(DOM::Node* new_focus_target, DOM::Node* fallback_target = nullptr, Optional<DeprecatedString> focus_trigger = {});
+void run_focusing_steps(DOM::Node* new_focus_target, DOM::Node* fallback_target = nullptr, Optional<ByteString> focus_trigger = {});
 void run_unfocusing_steps(DOM::Node* old_focus_target);
 
 }
diff --git a/Userland/Libraries/LibWeb/HTML/FormControlInfrastructure.cpp b/Userland/Libraries/LibWeb/HTML/FormControlInfrastructure.cpp
index 7ce44682967..54e318631be 100644
--- a/Userland/Libraries/LibWeb/HTML/FormControlInfrastructure.cpp
+++ b/Userland/Libraries/LibWeb/HTML/FormControlInfrastructure.cpp
@@ -107,13 +107,13 @@ WebIDL::ExceptionOr<Optional<Vector<XHR::FormDataEntry>>> construct_entry_list(J
             continue;
 
         // 5. Let name be the value of the field element's name attribute.
-        auto name = TRY_OR_THROW_OOM(vm, String::from_deprecated_string(control->name()));
+        auto name = TRY_OR_THROW_OOM(vm, String::from_byte_string(control->name()));
 
         // 6. If the field element is a select element, then for each option element in the select element's list of options whose selectedness is true and that is not disabled, create an entry with name and the value of the option element, and append it to entry list.
         if (auto* select_element = dynamic_cast<HTML::HTMLSelectElement*>(control.ptr())) {
             for (auto const& option_element : select_element->list_of_options()) {
                 if (option_element->selected() && !option_element->disabled()) {
-                    auto option_name = TRY_OR_THROW_OOM(vm, String::from_deprecated_string(option_element->name()));
+                    auto option_name = TRY_OR_THROW_OOM(vm, String::from_byte_string(option_element->name()));
                     auto option_value = option_element->value();
                     TRY_OR_THROW_OOM(vm, entry_list.try_append(XHR::FormDataEntry { .name = move(option_name), .value = move(option_value) }));
                 }
@@ -127,7 +127,7 @@ WebIDL::ExceptionOr<Optional<Vector<XHR::FormDataEntry>>> construct_entry_list(J
                 value = "on"_string;
 
             // 2. Create an entry with name and value, and append it to entry list.
-            auto checkbox_or_radio_element_name = TRY_OR_THROW_OOM(vm, String::from_deprecated_string(checkbox_or_radio_element->name()));
+            auto checkbox_or_radio_element_name = TRY_OR_THROW_OOM(vm, String::from_byte_string(checkbox_or_radio_element->name()));
             TRY_OR_THROW_OOM(vm, entry_list.try_append(XHR::FormDataEntry { .name = move(checkbox_or_radio_element_name), .value = move(value) }));
         }
         // 8. Otherwise, if the field element is an input element whose type attribute is in the File Upload state, then:
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLAnchorElement.h b/Userland/Libraries/LibWeb/HTML/HTMLAnchorElement.h
index ef454c9b732..00681f9afc9 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLAnchorElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLAnchorElement.h
@@ -20,9 +20,9 @@ class HTMLAnchorElement final
 public:
     virtual ~HTMLAnchorElement() override;
 
-    DeprecatedString rel() const { return deprecated_attribute(HTML::AttributeNames::rel); }
-    DeprecatedString target() const { return deprecated_attribute(HTML::AttributeNames::target); }
-    DeprecatedString download() const { return deprecated_attribute(HTML::AttributeNames::download); }
+    ByteString rel() const { return deprecated_attribute(HTML::AttributeNames::rel); }
+    ByteString target() const { return deprecated_attribute(HTML::AttributeNames::target); }
+    ByteString download() const { return deprecated_attribute(HTML::AttributeNames::download); }
 
     String text() const;
     void set_text(String const&);
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLBodyElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLBodyElement.cpp
index 47cf404eb40..72f3df83699 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLBodyElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLBodyElement.cpp
@@ -62,17 +62,17 @@ void HTMLBodyElement::attribute_changed(FlyString const& name, Optional<String>
     HTMLElement::attribute_changed(name, value);
     if (name.equals_ignoring_ascii_case("link"sv)) {
         // https://html.spec.whatwg.org/multipage/rendering.html#the-page:rules-for-parsing-a-legacy-colour-value-3
-        auto color = parse_legacy_color_value(value.value_or(String {}).to_deprecated_string());
+        auto color = parse_legacy_color_value(value.value_or(String {}).to_byte_string());
         if (color.has_value())
             document().set_link_color(color.value());
     } else if (name.equals_ignoring_ascii_case("alink"sv)) {
         // https://html.spec.whatwg.org/multipage/rendering.html#the-page:rules-for-parsing-a-legacy-colour-value-5
-        auto color = parse_legacy_color_value(value.value_or(String {}).to_deprecated_string());
+        auto color = parse_legacy_color_value(value.value_or(String {}).to_byte_string());
         if (color.has_value())
             document().set_active_link_color(color.value());
     } else if (name.equals_ignoring_ascii_case("vlink"sv)) {
         // https://html.spec.whatwg.org/multipage/rendering.html#the-page:rules-for-parsing-a-legacy-colour-value-4
-        auto color = parse_legacy_color_value(value.value_or(String {}).to_deprecated_string());
+        auto color = parse_legacy_color_value(value.value_or(String {}).to_byte_string());
         if (color.has_value())
             document().set_visited_link_color(color.value());
     } else if (name.equals_ignoring_ascii_case("background"sv)) {
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLFormElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLFormElement.cpp
index 953eec60dcb..39adfef2562 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLFormElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLFormElement.cpp
@@ -162,7 +162,7 @@ WebIDL::ExceptionOr<void> HTMLFormElement::submit_form(JS::NonnullGCPtr<HTMLElem
 
     // 13. If action is the empty string, let action be the URL of the form document.
     if (action.is_empty())
-        action = form_document->url_string().to_deprecated_string();
+        action = form_document->url_string().to_byte_string();
 
     // 14. Parse a URL given action, relative to the submitter element's node document. If this fails, return.
     // 15. Let parsed action be the resulting URL record.
@@ -302,7 +302,7 @@ void HTMLFormElement::remove_associated_element(Badge<FormAssociatedElement>, HT
 }
 
 // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#concept-fs-action
-DeprecatedString HTMLFormElement::action_from_form_element(JS::NonnullGCPtr<HTMLElement> element) const
+ByteString HTMLFormElement::action_from_form_element(JS::NonnullGCPtr<HTMLElement> element) const
 {
     // The action of an element is the value of the element's formaction attribute, if the element is a submit button
     // and has such an attribute, or the value of its form owner's action attribute, if it has one, or else the empty
@@ -314,7 +314,7 @@ DeprecatedString HTMLFormElement::action_from_form_element(JS::NonnullGCPtr<HTML
     if (this->has_attribute(AttributeNames::action))
         return deprecated_attribute(AttributeNames::action);
 
-    return DeprecatedString::empty();
+    return ByteString::empty();
 }
 
 // https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#form-submission-attributes:attr-fs-method-2
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLFormElement.h b/Userland/Libraries/LibWeb/HTML/HTMLFormElement.h
index 346cdd5ec88..b5f24864ce2 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLFormElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLFormElement.h
@@ -35,7 +35,7 @@ class HTMLFormElement final : public HTMLElement {
 public:
     virtual ~HTMLFormElement() override;
 
-    DeprecatedString action_from_form_element(JS::NonnullGCPtr<HTMLElement> element) const;
+    ByteString action_from_form_element(JS::NonnullGCPtr<HTMLElement> element) const;
 
     enum class MethodAttributeState {
 #define __ENUMERATE_FORM_METHOD_ATTRIBUTE(_, state) state,
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp b/Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp
index 4040ca9e246..388806680fe 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp
@@ -50,7 +50,7 @@ String HTMLHyperlinkElementUtils::origin() const
         return String {};
 
     // 3. Return the serialization of this element's url's origin.
-    return MUST(String::from_deprecated_string(m_url->serialize_origin()));
+    return MUST(String::from_byte_string(m_url->serialize_origin()));
 }
 
 // https://html.spec.whatwg.org/multipage/links.html#dom-hyperlink-protocol
@@ -294,7 +294,7 @@ String HTMLHyperlinkElementUtils::pathname() const
     // 4. If url's cannot-be-a-base-URL is true, then return url's path[0].
     // 5. If url's path is empty, then return the empty string.
     // 6. Return "/", followed by the strings in url's path (including empty strings), separated from each other by "/".
-    return MUST(String::from_deprecated_string(m_url->serialize_path()));
+    return MUST(String::from_byte_string(m_url->serialize_path()));
 }
 
 // https://html.spec.whatwg.org/multipage/links.html#dom-hyperlink-pathname
@@ -437,7 +437,7 @@ String HTMLHyperlinkElementUtils::href() const
         return href_content_attribute.release_value();
 
     // 5. Return url, serialized.
-    return MUST(String::from_deprecated_string(url->serialize()));
+    return MUST(String::from_byte_string(url->serialize()));
 }
 
 // https://html.spec.whatwg.org/multipage/links.html#dom-hyperlink-href
@@ -505,7 +505,7 @@ void HTMLHyperlinkElementUtils::follow_the_hyperlink(Optional<String> hyperlink_
         return;
 
     // 10. If that is successful, let URL be the resulting URL string.
-    auto url_string = url.to_deprecated_string();
+    auto url_string = url.to_byte_string();
 
     // 12. If hyperlinkSuffix is non-null, then append it to URL.
     if (hyperlink_suffix.has_value()) {
@@ -513,7 +513,7 @@ void HTMLHyperlinkElementUtils::follow_the_hyperlink(Optional<String> hyperlink_
         url_builder.append(url_string);
         url_builder.append(*hyperlink_suffix);
 
-        url_string = url_builder.to_deprecated_string();
+        url_string = url_builder.to_byte_string();
     }
 
     // FIXME: 12. If subject's link types includes the noreferrer keyword, then set referrerPolicy to "no-referrer".
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLImageElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLImageElement.cpp
index e2dc91aed6d..62188dd08aa 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLImageElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLImageElement.cpp
@@ -349,7 +349,7 @@ ErrorOr<void> HTMLImageElement::update_the_image_data(bool restart_animations, b
     //    then set selected source to the value of the element's src attribute
     //    and set selected pixel density to 1.0.
     if (!uses_srcset_or_picture() && has_attribute(HTML::AttributeNames::src) && !deprecated_attribute(HTML::AttributeNames::src).is_empty()) {
-        selected_source = TRY(String::from_deprecated_string(deprecated_attribute(HTML::AttributeNames::src)));
+        selected_source = TRY(String::from_byte_string(deprecated_attribute(HTML::AttributeNames::src)));
         selected_pixel_density = 1.0f;
     }
 
@@ -361,7 +361,7 @@ ErrorOr<void> HTMLImageElement::update_the_image_data(bool restart_animations, b
         // 1. Parse selected source, relative to the element's node document.
         //    If that is not successful, then abort this inner set of steps.
         //    Otherwise, let urlString be the resulting URL string.
-        auto url_string = document().parse_url(selected_source.value().to_deprecated_string());
+        auto url_string = document().parse_url(selected_source.value().to_byte_string());
         if (!url_string.is_valid())
             goto after_step_7;
 
@@ -460,7 +460,7 @@ after_step_7:
         }
 
         // 12. Parse selected source, relative to the element's node document, and let urlString be the resulting URL string.
-        auto url_string = document().parse_url(selected_source.value().url.to_deprecated_string());
+        auto url_string = document().parse_url(selected_source.value().url.to_byte_string());
         // If that is not successful, then:
         if (!url_string.is_valid()) {
             // 1. Abort the image request for the current request and the pending request.
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLImageElement.h b/Userland/Libraries/LibWeb/HTML/HTMLImageElement.h
index 9bd5e573a26..8e5a1f117a8 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLImageElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLImageElement.h
@@ -39,8 +39,8 @@ public:
 
     virtual void attribute_changed(FlyString const& name, Optional<String> const& value) override;
 
-    DeprecatedString alt() const { return deprecated_attribute(HTML::AttributeNames::alt); }
-    DeprecatedString src() const { return deprecated_attribute(HTML::AttributeNames::src); }
+    ByteString alt() const { return deprecated_attribute(HTML::AttributeNames::alt); }
+    ByteString src() const { return deprecated_attribute(HTML::AttributeNames::src); }
 
     RefPtr<Gfx::ImmutableBitmap> immutable_bitmap() const;
     RefPtr<Gfx::Bitmap const> bitmap() const;
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
index b7cb84e2a26..65583849380 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.cpp
@@ -519,7 +519,7 @@ String HTMLInputElement::placeholder() const
 }
 
 // https://html.spec.whatwg.org/multipage/input.html#attr-input-placeholder
-Optional<DeprecatedString> HTMLInputElement::placeholder_value() const
+Optional<ByteString> HTMLInputElement::placeholder_value() const
 {
     if (!m_text_node || !m_text_node->data().is_empty())
         return {};
@@ -527,7 +527,7 @@ Optional<DeprecatedString> HTMLInputElement::placeholder_value() const
         return {};
     if (!has_attribute(HTML::AttributeNames::placeholder))
         return {};
-    return placeholder().to_deprecated_string();
+    return placeholder().to_byte_string();
 }
 
 void HTMLInputElement::create_shadow_tree_if_needed()
@@ -966,7 +966,7 @@ void HTMLInputElement::legacy_pre_activation_behavior()
     // has its checkedness set to true, if any, and then set this element's
     // checkedness to true.
     if (type_state() == TypeAttributeState::RadioButton) {
-        DeprecatedString name = this->name();
+        ByteString name = this->name();
 
         document().for_each_in_inclusive_subtree_of_type<HTML::HTMLInputElement>([&](auto& element) {
             if (element.checked() && is_in_same_radio_button_group(*this, element)) {
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h
index df1754f9dc0..c3b1717f4ec 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLInputElement.h
@@ -63,8 +63,8 @@ public:
     TypeAttributeState type_state() const { return m_type; }
     WebIDL::ExceptionOr<void> set_type(String const&);
 
-    DeprecatedString default_value() const { return deprecated_attribute(HTML::AttributeNames::value); }
-    DeprecatedString name() const { return deprecated_attribute(HTML::AttributeNames::name); }
+    ByteString default_value() const { return deprecated_attribute(HTML::AttributeNames::value); }
+    ByteString name() const { return deprecated_attribute(HTML::AttributeNames::name); }
 
     virtual String value() const override;
     WebIDL::ExceptionOr<void> set_value(String const&);
@@ -72,7 +72,7 @@ public:
     void commit_pending_changes();
 
     String placeholder() const;
-    Optional<DeprecatedString> placeholder_value() const;
+    Optional<ByteString> placeholder_value() const;
 
     bool checked() const { return m_checked; }
     enum class ChangeSource {
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLLinkElement.h b/Userland/Libraries/LibWeb/HTML/HTMLLinkElement.h
index 20f824c185b..fb7418fa1a1 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLLinkElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLLinkElement.h
@@ -29,9 +29,9 @@ public:
 
     virtual void inserted() override;
 
-    DeprecatedString rel() const { return deprecated_attribute(HTML::AttributeNames::rel); }
-    DeprecatedString type() const { return deprecated_attribute(HTML::AttributeNames::type); }
-    DeprecatedString href() const { return deprecated_attribute(HTML::AttributeNames::href); }
+    ByteString rel() const { return deprecated_attribute(HTML::AttributeNames::rel); }
+    ByteString type() const { return deprecated_attribute(HTML::AttributeNames::type); }
+    ByteString href() const { return deprecated_attribute(HTML::AttributeNames::href); }
 
     bool has_loaded_icon() const;
     bool load_favicon_and_use_if_window_is_active();
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLMediaElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLMediaElement.cpp
index f8d34bd1c91..4f2b6910eb3 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLMediaElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLMediaElement.cpp
@@ -578,7 +578,7 @@ public:
         //    empty string, then end the synchronous section, and jump down to the failed with elements step below.
         String candiate_src;
         if (m_candidate->has_attribute(HTML::AttributeNames::src))
-            candiate_src = TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_candidate->deprecated_attribute(HTML::AttributeNames::src)));
+            candiate_src = TRY_OR_THROW_OOM(vm, String::from_byte_string(m_candidate->deprecated_attribute(HTML::AttributeNames::src)));
 
         if (candiate_src.is_empty()) {
             TRY(failed_with_elements());
@@ -589,7 +589,7 @@ public:
         //    would have resulted from parsing the URL specified by candidate's src attribute's value relative to the
         //    candidate's node document when the src attribute was last changed.
         auto url_record = m_candidate->document().parse_url(candiate_src);
-        auto url_string = TRY_OR_THROW_OOM(vm, String::from_deprecated_string(url_record.to_deprecated_string()));
+        auto url_string = TRY_OR_THROW_OOM(vm, String::from_byte_string(url_record.to_byte_string()));
 
         // 4. ⌛ If urlString was not obtained successfully, then end the synchronous section, and jump down to the failed
         //    with elements step below.
@@ -837,7 +837,7 @@ WebIDL::ExceptionOr<void> HTMLMediaElement::select_resource()
 
         // 3. ⌛ If urlString was obtained successfully, set the currentSrc attribute to urlString.
         if (url_record.is_valid())
-            m_current_src = TRY_OR_THROW_OOM(vm, String::from_deprecated_string(url_record.to_deprecated_string()));
+            m_current_src = TRY_OR_THROW_OOM(vm, String::from_byte_string(url_record.to_byte_string()));
 
         // 4. End the synchronous section, continuing the remaining steps in parallel.
 
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLObjectElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLObjectElement.cpp
index eeb80a2aac0..3bb5602500e 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLObjectElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLObjectElement.cpp
@@ -170,7 +170,7 @@ void HTMLObjectElement::resource_did_load()
     // 4.8. Determine the resource type, as follows:
 
     // 1. Let the resource type be unknown.
-    Optional<DeprecatedString> resource_type;
+    Optional<ByteString> resource_type;
 
     // FIXME: 2. If the user agent is configured to strictly obey Content-Type headers for this resource, and the resource has associated Content-Type metadata, then let the resource type be the type specified in the resource's Content-Type metadata, and jump to the step below labeled handler.
     // FIXME: 3. If there is a type attribute present on the object element, and that attribute's value is not a type that the user agent supports, but it is a type that a plugin supports, then let the resource type be the type specified in that type attribute, and jump to the step below labeled handler.
@@ -203,7 +203,7 @@ void HTMLObjectElement::resource_did_load()
     }
     // * Otherwise, if the resource does not have associated Content-Type metadata
     else {
-        Optional<DeprecatedString> tentative_type;
+        Optional<ByteString> tentative_type;
 
         // 1. If there is a type attribute present on the object element, then let the tentative type be the type specified in that type attribute.
         //    Otherwise, let tentative type be the computed type of the resource.
@@ -235,7 +235,7 @@ static bool is_xml_mime_type(StringView resource_type)
 }
 
 // https://html.spec.whatwg.org/multipage/iframe-embed-object.html#the-object-element:plugin-11
-void HTMLObjectElement::run_object_representation_handler_steps(Optional<DeprecatedString> resource_type)
+void HTMLObjectElement::run_object_representation_handler_steps(Optional<ByteString> resource_type)
 {
     // 4.9. Handler: Handle the content as given by the first of the following cases that matches:
 
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLObjectElement.h b/Userland/Libraries/LibWeb/HTML/HTMLObjectElement.h
index 580d3d63725..252ccb04f60 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLObjectElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLObjectElement.h
@@ -40,7 +40,7 @@ public:
     String data() const;
     void set_data(String const& data) { MUST(set_attribute(HTML::AttributeNames::data, data)); }
 
-    DeprecatedString type() const { return deprecated_attribute(HTML::AttributeNames::type); }
+    ByteString type() const { return deprecated_attribute(HTML::AttributeNames::type); }
 
     // ^FormAssociatedElement
     // https://html.spec.whatwg.org/multipage/forms.html#category-listed
@@ -58,7 +58,7 @@ private:
     bool has_ancestor_media_element_or_object_element_not_showing_fallback_content() const;
 
     void queue_element_task_to_run_object_representation_steps();
-    void run_object_representation_handler_steps(Optional<DeprecatedString> resource_type);
+    void run_object_representation_handler_steps(Optional<ByteString> resource_type);
     void run_object_representation_completed_steps(Representation);
     void run_object_representation_fallback_steps();
 
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLOutputElement.h b/Userland/Libraries/LibWeb/HTML/HTMLOutputElement.h
index 8d046329f76..45d5925c25f 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLOutputElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLOutputElement.h
@@ -23,9 +23,9 @@ class HTMLOutputElement final
 public:
     virtual ~HTMLOutputElement() override;
 
-    DeprecatedString const& type() const
+    ByteString const& type() const
     {
-        static DeprecatedString output = "output";
+        static ByteString output = "output";
         return output;
     }
 
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLScriptElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLScriptElement.cpp
index 1e273fcf6a3..a0ea466d717 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLScriptElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLScriptElement.cpp
@@ -177,7 +177,7 @@ void HTMLScriptElement::prepare_script()
     //    - el has a type attribute whose value is the empty string;
     //    - el has no type attribute but it has a language attribute and that attribute's value is the empty string; or
     //    - el has neither a type attribute nor a language attribute
-    DeprecatedString script_block_type;
+    ByteString script_block_type;
     bool has_type_attribute = has_attribute(HTML::AttributeNames::type);
     bool has_language_attribute = has_attribute(HTML::AttributeNames::language);
     if ((has_type_attribute && deprecated_attribute(HTML::AttributeNames::type).is_empty())
@@ -194,7 +194,7 @@ void HTMLScriptElement::prepare_script()
     // Otherwise, el has a non-empty language attribute;
     else if (!deprecated_attribute(HTML::AttributeNames::language).is_empty()) {
         // let the script block's type string be the concatenation of "text/" and the value of el's language attribute.
-        script_block_type = DeprecatedString::formatted("text/{}", deprecated_attribute(HTML::AttributeNames::language));
+        script_block_type = ByteString::formatted("text/{}", deprecated_attribute(HTML::AttributeNames::language));
     }
 
     // 9. If the script block's type string is a JavaScript MIME type essence match,
@@ -307,7 +307,7 @@ void HTMLScriptElement::prepare_script()
     String integrity_metadata;
     if (has_attribute(HTML::AttributeNames::integrity)) {
         auto integrity = deprecated_attribute(HTML::AttributeNames::integrity);
-        integrity_metadata = String::from_deprecated_string(integrity).release_value_but_fixme_should_propagate_errors();
+        integrity_metadata = String::from_byte_string(integrity).release_value_but_fixme_should_propagate_errors();
     }
 
     // 26. Let referrer policy be the current state of el's referrerpolicy content attribute.
@@ -409,7 +409,7 @@ void HTMLScriptElement::prepare_script()
         if (m_script_type == ScriptType::Classic) {
             // 1. Let script be the result of creating a classic script using source text, settings object, base URL, and options.
             // FIXME: Pass options.
-            auto script = ClassicScript::create(m_document->url().to_deprecated_string(), source_text, settings_object, base_url, m_source_line_number);
+            auto script = ClassicScript::create(m_document->url().to_byte_string(), source_text, settings_object, base_url, m_source_line_number);
 
             // 2. Mark as ready el given script.
             mark_as_ready(Result(move(script)));
@@ -429,7 +429,7 @@ void HTMLScriptElement::prepare_script()
 
             // 2. Fetch an inline module script graph, given source text, base URL, settings object, options, and with the following steps given result:
             // FIXME: Pass options
-            fetch_inline_module_script_graph(realm(), m_document->url().to_deprecated_string(), source_text.to_deprecated_string(), base_url, document().relevant_settings_object(), steps);
+            fetch_inline_module_script_graph(realm(), m_document->url().to_byte_string(), source_text.to_byte_string(), base_url, document().relevant_settings_object(), steps);
         }
         // -> "importmap"
         else if (m_script_type == ScriptType::ImportMap) {
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLTableElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLTableElement.cpp
index a26b714df12..e8de4a22848 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLTableElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLTableElement.cpp
@@ -44,7 +44,7 @@ void HTMLTableElement::visit_edges(Cell::Visitor& visitor)
     visitor.visit(m_t_bodies);
 }
 
-static unsigned parse_border(DeprecatedString const& value)
+static unsigned parse_border(ByteString const& value)
 {
     return value.to_uint().value_or(0);
 }
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLTitleElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLTitleElement.cpp
index a5630ce6c58..46951fe7c7e 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLTitleElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLTitleElement.cpp
@@ -30,15 +30,15 @@ void HTMLTitleElement::children_changed()
 {
     HTMLElement::children_changed();
     if (navigable() && navigable()->is_traversable()) {
-        navigable()->traversable_navigable()->page().client().page_did_change_title(document().title().to_deprecated_string());
+        navigable()->traversable_navigable()->page().client().page_did_change_title(document().title().to_byte_string());
     }
 }
 
 // https://html.spec.whatwg.org/multipage/semantics.html#dom-title-text
-DeprecatedString HTMLTitleElement::text()
+ByteString HTMLTitleElement::text()
 {
     // The text attribute's getter must return this title element's child text content.
-    return child_text_content().to_deprecated_string();
+    return child_text_content().to_byte_string();
 }
 
 // https://html.spec.whatwg.org/multipage/semantics.html#dom-title-text
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLTitleElement.h b/Userland/Libraries/LibWeb/HTML/HTMLTitleElement.h
index a42bc295169..5e2496c980a 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLTitleElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLTitleElement.h
@@ -17,7 +17,7 @@ class HTMLTitleElement final : public HTMLElement {
 public:
     virtual ~HTMLTitleElement() override;
 
-    DeprecatedString text();
+    ByteString text();
     void set_text(String const& value);
 
 private:
diff --git a/Userland/Libraries/LibWeb/HTML/History.cpp b/Userland/Libraries/LibWeb/HTML/History.cpp
index 5ada1f616b3..c0d8087c028 100644
--- a/Userland/Libraries/LibWeb/HTML/History.cpp
+++ b/Userland/Libraries/LibWeb/HTML/History.cpp
@@ -172,7 +172,7 @@ WebIDL::ExceptionOr<void> History::shared_history_push_replace_state(JS::Value v
     if (url.has_value() && !url->is_empty()) {
 
         // 1. Parse url, relative to the relevant settings object of history.
-        auto parsed_url = relevant_settings_object(*this).parse_url(url->to_deprecated_string());
+        auto parsed_url = relevant_settings_object(*this).parse_url(url->to_byte_string());
 
         // 2. If that fails, then throw a "SecurityError" DOMException.
         if (!parsed_url.is_valid())
diff --git a/Userland/Libraries/LibWeb/HTML/Location.cpp b/Userland/Libraries/LibWeb/HTML/Location.cpp
index 338b73ae75a..8bc0b98a0d3 100644
--- a/Userland/Libraries/LibWeb/HTML/Location.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Location.cpp
@@ -116,7 +116,7 @@ WebIDL::ExceptionOr<String> Location::href() const
         return WebIDL::SecurityError::create(realm(), "Location's relevant document is not same origin-domain with the entry settings object's origin"_fly_string);
 
     // 2. Return this's url, serialized.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(url().serialize()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(url().serialize()));
 }
 
 // https://html.spec.whatwg.org/multipage/history.html#the-location-interface:dom-location-href-2
@@ -131,7 +131,7 @@ WebIDL::ExceptionOr<void> Location::set_href(String const& new_href)
         return {};
 
     // 2. Parse the given value relative to the entry settings object. If that failed, throw a TypeError exception.
-    auto href_url = window.associated_document().parse_url(new_href.to_deprecated_string());
+    auto href_url = window.associated_document().parse_url(new_href.to_byte_string());
     if (!href_url.is_valid())
         return vm.throw_completion<JS::URIError>(TRY_OR_THROW_OOM(vm, String::formatted("Invalid URL '{}'", new_href)));
 
@@ -152,7 +152,7 @@ WebIDL::ExceptionOr<String> Location::origin() const
         return WebIDL::SecurityError::create(realm(), "Location's relevant document is not same origin-domain with the entry settings object's origin"_fly_string);
 
     // 2. Return the serialization of this's url's origin.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(url().serialize_origin()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(url().serialize_origin()));
 }
 
 // https://html.spec.whatwg.org/multipage/history.html#dom-location-protocol
@@ -269,7 +269,7 @@ WebIDL::ExceptionOr<String> Location::pathname() const
         return WebIDL::SecurityError::create(realm(), "Location's relevant document is not same origin-domain with the entry settings object's origin"_fly_string);
 
     // 2. Return the result of URL path serializing this Location object's url.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(url().serialize_path()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(url().serialize_path()));
 }
 
 WebIDL::ExceptionOr<void> Location::set_pathname(String const&)
diff --git a/Userland/Libraries/LibWeb/HTML/Navigable.cpp b/Userland/Libraries/LibWeb/HTML/Navigable.cpp
index be3d373d5dd..3ad62b3c485 100644
--- a/Userland/Libraries/LibWeb/HTML/Navigable.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Navigable.cpp
@@ -674,7 +674,7 @@ static WebIDL::ExceptionOr<Variant<Empty, NavigationParams, NonFetchSchemeNaviga
     request->set_credentials_mode(Fetch::Infrastructure::Request::CredentialsMode::Include);
     request->set_use_url_credentials(true);
     request->set_redirect_mode(Fetch::Infrastructure::Request::RedirectMode::Manual);
-    auto replaces_client_id = TRY_OR_THROW_OOM(vm, String::from_deprecated_string(active_document.relevant_settings_object().id));
+    auto replaces_client_id = TRY_OR_THROW_OOM(vm, String::from_byte_string(active_document.relevant_settings_object().id));
     request->set_replaces_client_id(replaces_client_id);
     request->set_mode(Fetch::Infrastructure::Request::Mode::Navigate);
     request->set_referrer(entry->document_state->request_referrer());
diff --git a/Userland/Libraries/LibWeb/HTML/NavigationDestination.cpp b/Userland/Libraries/LibWeb/HTML/NavigationDestination.cpp
index 202eebee0f6..d42591b1a88 100644
--- a/Userland/Libraries/LibWeb/HTML/NavigationDestination.cpp
+++ b/Userland/Libraries/LibWeb/HTML/NavigationDestination.cpp
@@ -43,7 +43,7 @@ void NavigationDestination::visit_edges(JS::Cell::Visitor& visitor)
 WebIDL::ExceptionOr<String> NavigationDestination::url() const
 {
     // The url getter steps are to return this's URL, serialized.
-    return TRY_OR_THROW_OOM(vm(), String::from_deprecated_string(m_url.serialize()));
+    return TRY_OR_THROW_OOM(vm(), String::from_byte_string(m_url.serialize()));
 }
 
 // https://html.spec.whatwg.org/multipage/nav-history-apis.html#dom-navigationdestination-key
diff --git a/Userland/Libraries/LibWeb/HTML/NavigationHistoryEntry.cpp b/Userland/Libraries/LibWeb/HTML/NavigationHistoryEntry.cpp
index 787798c98a2..d4f6500a315 100644
--- a/Userland/Libraries/LibWeb/HTML/NavigationHistoryEntry.cpp
+++ b/Userland/Libraries/LibWeb/HTML/NavigationHistoryEntry.cpp
@@ -65,7 +65,7 @@ WebIDL::ExceptionOr<Optional<String>> NavigationHistoryEntry::url() const
         return OptionalNone {};
 
     // 5. Return she's URL, serialized.
-    return TRY_OR_THROW_OOM(vm(), String::from_deprecated_string(she->url.serialize()));
+    return TRY_OR_THROW_OOM(vm(), String::from_byte_string(she->url.serialize()));
 }
 
 // https://html.spec.whatwg.org/multipage/nav-history-apis.html#concept-navigationhistoryentry-key
diff --git a/Userland/Libraries/LibWeb/HTML/NavigatorID.cpp b/Userland/Libraries/LibWeb/HTML/NavigatorID.cpp
index 74bcefa5fd9..0a67784628f 100644
--- a/Userland/Libraries/LibWeb/HTML/NavigatorID.cpp
+++ b/Userland/Libraries/LibWeb/HTML/NavigatorID.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibWeb/HTML/NavigatorID.h>
 #include <LibWeb/Loader/ResourceLoader.h>
 
diff --git a/Userland/Libraries/LibWeb/HTML/NavigatorID.h b/Userland/Libraries/LibWeb/HTML/NavigatorID.h
index 93ff9981cd6..e1c23fd5b9e 100644
--- a/Userland/Libraries/LibWeb/HTML/NavigatorID.h
+++ b/Userland/Libraries/LibWeb/HTML/NavigatorID.h
@@ -45,7 +45,7 @@ public:
 
     // NOTE: If the navigator compatibility mode is Gecko, then the user agent must also support the following partial interface:
     //       bool taint_enabled()
-    //       DeprecatedString oscpu()
+    //       ByteString oscpu()
 };
 
 }
diff --git a/Userland/Libraries/LibWeb/HTML/Origin.h b/Userland/Libraries/LibWeb/HTML/Origin.h
index 44bcddac02e..f98d5e82cc9 100644
--- a/Userland/Libraries/LibWeb/HTML/Origin.h
+++ b/Userland/Libraries/LibWeb/HTML/Origin.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/URL.h>
 #include <AK/URLParser.h>
 
@@ -16,7 +16,7 @@ namespace Web::HTML {
 class Origin {
 public:
     Origin() = default;
-    Origin(Optional<DeprecatedString> const& scheme, AK::URL::Host const& host, u16 port)
+    Origin(Optional<ByteString> const& scheme, AK::URL::Host const& host, u16 port)
         : m_scheme(scheme)
         , m_host(host)
         , m_port(port)
@@ -72,7 +72,7 @@ public:
     }
 
     // https://html.spec.whatwg.org/multipage/origin.html#ascii-serialisation-of-an-origin
-    DeprecatedString serialize() const
+    ByteString serialize() const
     {
         // 1. If origin is an opaque origin, then return "null"
         if (is_opaque())
@@ -86,15 +86,15 @@ public:
         result.append("://"sv);
 
         // 4. Append origin's host, serialized, to result.
-        result.append(URLParser::serialize_host(host()).release_value_but_fixme_should_propagate_errors().to_deprecated_string());
+        result.append(URLParser::serialize_host(host()).release_value_but_fixme_should_propagate_errors().to_byte_string());
 
         // 5. If origin's port is non-null, append a U+003A COLON character (:), and origin's port, serialized, to result.
         if (port() != 0) {
             result.append(':');
-            result.append(DeprecatedString::number(port()));
+            result.append(ByteString::number(port()));
         }
         // 6. Return result
-        return result.to_deprecated_string();
+        return result.to_byte_string();
     }
 
     // https://html.spec.whatwg.org/multipage/origin.html#concept-origin-effective-domain
@@ -113,7 +113,7 @@ public:
     bool operator==(Origin const& other) const { return is_same_origin(other); }
 
 private:
-    Optional<DeprecatedString> m_scheme;
+    Optional<ByteString> m_scheme;
     AK::URL::Host m_host;
     u16 m_port { 0 };
 };
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLEncodingDetection.cpp b/Userland/Libraries/LibWeb/HTML/Parser/HTMLEncodingDetection.cpp
index cd1cf48f50c..0adde20be72 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLEncodingDetection.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLEncodingDetection.cpp
@@ -35,7 +35,7 @@ bool prescan_skip_whitespace_and_slashes(ByteBuffer const& input, size_t& positi
 }
 
 // https://html.spec.whatwg.org/multipage/urls-and-fetching.html#algorithm-for-extracting-a-character-encoding-from-a-meta-element
-Optional<StringView> extract_character_encoding_from_meta_element(DeprecatedString const& string)
+Optional<StringView> extract_character_encoding_from_meta_element(ByteString const& string)
 {
     // Checking for "charset" is case insensitive, as is getting an encoding.
     // Therefore, stick to lowercase from the start for simplicity.
@@ -158,7 +158,7 @@ value:
 }
 
 // https://html.spec.whatwg.org/multipage/parsing.html#prescan-a-byte-stream-to-determine-its-encoding
-Optional<DeprecatedString> run_prescan_byte_stream_algorithm(DOM::Document& document, ByteBuffer const& input)
+Optional<ByteString> run_prescan_byte_stream_algorithm(DOM::Document& document, ByteBuffer const& input)
 {
     // https://html.spec.whatwg.org/multipage/parsing.html#prescan-a-byte-stream-to-determine-its-encoding
 
@@ -191,7 +191,7 @@ Optional<DeprecatedString> run_prescan_byte_stream_algorithm(DOM::Document& docu
             Vector<FlyString> attribute_list {};
             bool got_pragma = false;
             Optional<bool> need_pragma {};
-            Optional<DeprecatedString> charset {};
+            Optional<ByteString> charset {};
 
             while (true) {
                 auto attribute = prescan_get_attribute(document, input, position);
@@ -205,7 +205,7 @@ Optional<DeprecatedString> run_prescan_byte_stream_algorithm(DOM::Document& docu
                 if (attribute_name == "http-equiv") {
                     got_pragma = attribute->value() == "content-type";
                 } else if (attribute_name == "content") {
-                    auto encoding = extract_character_encoding_from_meta_element(attribute->value().to_deprecated_string());
+                    auto encoding = extract_character_encoding_from_meta_element(attribute->value().to_byte_string());
                     if (encoding.has_value() && !charset.has_value()) {
                         charset = encoding.value();
                         need_pragma = true;
@@ -213,7 +213,7 @@ Optional<DeprecatedString> run_prescan_byte_stream_algorithm(DOM::Document& docu
                 } else if (attribute_name == "charset") {
                     auto maybe_charset = TextCodec::get_standardized_encoding(attribute->value());
                     if (maybe_charset.has_value()) {
-                        charset = Optional<DeprecatedString> { maybe_charset };
+                        charset = Optional<ByteString> { maybe_charset };
                         need_pragma = { false };
                     }
                 }
@@ -247,7 +247,7 @@ Optional<DeprecatedString> run_prescan_byte_stream_algorithm(DOM::Document& docu
 }
 
 // https://html.spec.whatwg.org/multipage/parsing.html#determining-the-character-encoding
-DeprecatedString run_encoding_sniffing_algorithm(DOM::Document& document, ByteBuffer const& input)
+ByteString run_encoding_sniffing_algorithm(DOM::Document& document, ByteBuffer const& input)
 {
     if (input.size() >= 2) {
         if (input[0] == 0xFE && input[1] == 0xFF) {
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLEncodingDetection.h b/Userland/Libraries/LibWeb/HTML/Parser/HTMLEncodingDetection.h
index cbade5f4670..22a63013312 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLEncodingDetection.h
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLEncodingDetection.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <LibJS/Heap/GCPtr.h>
 #include <LibWeb/Forward.h>
@@ -16,9 +16,9 @@ namespace Web::HTML {
 bool prescan_should_abort(ByteBuffer const& input, size_t const& position);
 bool prescan_is_whitespace_or_slash(u8 const& byte);
 bool prescan_skip_whitespace_and_slashes(ByteBuffer const& input, size_t& position);
-Optional<StringView> extract_character_encoding_from_meta_element(DeprecatedString const&);
+Optional<StringView> extract_character_encoding_from_meta_element(ByteString const&);
 JS::GCPtr<DOM::Attr> prescan_get_attribute(DOM::Document&, ByteBuffer const& input, size_t& position);
-Optional<DeprecatedString> run_prescan_byte_stream_algorithm(DOM::Document&, ByteBuffer const& input);
-DeprecatedString run_encoding_sniffing_algorithm(DOM::Document&, ByteBuffer const& input);
+Optional<ByteString> run_prescan_byte_stream_algorithm(DOM::Document&, ByteBuffer const& input);
+ByteString run_encoding_sniffing_algorithm(DOM::Document&, ByteBuffer const& input);
 
 }
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
index 57d9adbd31d..c1d6672506f 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.cpp
@@ -132,7 +132,7 @@ static bool is_html_integration_point(DOM::Element const& element)
     return false;
 }
 
-HTMLParser::HTMLParser(DOM::Document& document, StringView input, DeprecatedString const& encoding)
+HTMLParser::HTMLParser(DOM::Document& document, StringView input, ByteString const& encoding)
     : m_tokenizer(input, encoding)
     , m_scripting_enabled(document.is_scripting_enabled())
     , m_document(JS::make_handle(document))
@@ -219,7 +219,7 @@ void HTMLParser::run()
 void HTMLParser::run(const AK::URL& url)
 {
     m_document->set_url(url);
-    m_document->set_source(MUST(String::from_deprecated_string(m_tokenizer.source())));
+    m_document->set_source(MUST(String::from_byte_string(m_tokenizer.source())));
     run();
     the_end();
     m_document->detach_parser({});
@@ -4223,13 +4223,13 @@ JS::NonnullGCPtr<HTMLParser> HTMLParser::create_for_scripting(DOM::Document& doc
 JS::NonnullGCPtr<HTMLParser> HTMLParser::create_with_uncertain_encoding(DOM::Document& document, ByteBuffer const& input)
 {
     if (document.has_encoding())
-        return document.heap().allocate_without_realm<HTMLParser>(document, input, document.encoding().value().to_deprecated_string());
+        return document.heap().allocate_without_realm<HTMLParser>(document, input, document.encoding().value().to_byte_string());
     auto encoding = run_encoding_sniffing_algorithm(document, input);
     dbgln_if(HTML_PARSER_DEBUG, "The encoding sniffing algorithm returned encoding '{}'", encoding);
     return document.heap().allocate_without_realm<HTMLParser>(document, input, encoding);
 }
 
-JS::NonnullGCPtr<HTMLParser> HTMLParser::create(DOM::Document& document, StringView input, DeprecatedString const& encoding)
+JS::NonnullGCPtr<HTMLParser> HTMLParser::create(DOM::Document& document, StringView input, ByteString const& encoding)
 {
     return document.heap().allocate_without_realm<HTMLParser>(document, input, encoding);
 }
@@ -4545,7 +4545,7 @@ RefPtr<CSS::StyleValue> parse_nonzero_dimension_value(StringView string)
 }
 
 // https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#rules-for-parsing-a-legacy-colour-value
-Optional<Color> parse_legacy_color_value(DeprecatedString input)
+Optional<Color> parse_legacy_color_value(ByteString input)
 {
     // 1. Let input be the string being parsed
     // 2. If input is the empty string, then return an error.
@@ -4591,7 +4591,7 @@ Optional<Color> parse_legacy_color_value(DeprecatedString input)
     }
 
     // 7. Replace any code points greater than U+FFFF in input (i.e., any characters that are not in the basic multilingual plane) with the two-character string "00".
-    auto replace_non_basic_multilingual_code_points = [](StringView string) -> DeprecatedString {
+    auto replace_non_basic_multilingual_code_points = [](StringView string) -> ByteString {
         StringBuilder builder;
         for (auto code_point : Utf8View { string }) {
             if (code_point > 0xFFFF)
@@ -4599,7 +4599,7 @@ Optional<Color> parse_legacy_color_value(DeprecatedString input)
             else
                 builder.append_code_point(code_point);
         }
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
     input = replace_non_basic_multilingual_code_points(input);
 
@@ -4612,7 +4612,7 @@ Optional<Color> parse_legacy_color_value(DeprecatedString input)
         input = input.substring(1);
 
     // 10. Replace any character in input that is not an ASCII hex digit with the character U+0030 DIGIT ZERO (0).
-    auto replace_non_ascii_hex = [](StringView string) -> DeprecatedString {
+    auto replace_non_ascii_hex = [](StringView string) -> ByteString {
         StringBuilder builder;
         for (auto code_point : Utf8View { string }) {
             if (is_ascii_hex_digit(code_point))
@@ -4620,7 +4620,7 @@ Optional<Color> parse_legacy_color_value(DeprecatedString input)
             else
                 builder.append_code_point('0');
         }
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
     input = replace_non_ascii_hex(input);
 
@@ -4629,7 +4629,7 @@ Optional<Color> parse_legacy_color_value(DeprecatedString input)
     builder.append(input);
     while (builder.length() == 0 || (builder.length() % 3 != 0))
         builder.append_code_point('0');
-    input = builder.to_deprecated_string();
+    input = builder.to_byte_string();
 
     // 12. Split input into three strings of equal code point length, to obtain three components. Let length be the code point length that all of those components have (one third the code point length of input).
     auto length = input.length() / 3;
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.h b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.h
index 9f9c3e2e5f6..5ac01829190 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.h
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLParser.h
@@ -51,7 +51,7 @@ public:
 
     static JS::NonnullGCPtr<HTMLParser> create_for_scripting(DOM::Document&);
     static JS::NonnullGCPtr<HTMLParser> create_with_uncertain_encoding(DOM::Document&, ByteBuffer const& input);
-    static JS::NonnullGCPtr<HTMLParser> create(DOM::Document&, StringView input, DeprecatedString const& encoding);
+    static JS::NonnullGCPtr<HTMLParser> create(DOM::Document&, StringView input, ByteString const& encoding);
 
     void run();
     void run(const AK::URL&);
@@ -82,7 +82,7 @@ public:
     size_t script_nesting_level() const { return m_script_nesting_level; }
 
 private:
-    HTMLParser(DOM::Document&, StringView input, DeprecatedString const& encoding);
+    HTMLParser(DOM::Document&, StringView input, ByteString const& encoding);
     HTMLParser(DOM::Document&);
 
     virtual void visit_edges(Cell::Visitor&) override;
@@ -202,6 +202,6 @@ private:
 
 RefPtr<CSS::StyleValue> parse_dimension_value(StringView);
 RefPtr<CSS::StyleValue> parse_nonzero_dimension_value(StringView);
-Optional<Color> parse_legacy_color_value(DeprecatedString input);
+Optional<Color> parse_legacy_color_value(ByteString input);
 
 }
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLTokenizer.cpp b/Userland/Libraries/LibWeb/HTML/Parser/HTMLTokenizer.cpp
index 9330fdde957..fe9a4a0d529 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLTokenizer.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLTokenizer.cpp
@@ -2788,11 +2788,11 @@ HTMLTokenizer::HTMLTokenizer()
     m_source_positions.empend(0u, 0u);
 }
 
-HTMLTokenizer::HTMLTokenizer(StringView input, DeprecatedString const& encoding)
+HTMLTokenizer::HTMLTokenizer(StringView input, ByteString const& encoding)
 {
     auto decoder = TextCodec::decoder_for(encoding);
     VERIFY(decoder.has_value());
-    m_decoded_input = decoder->to_utf8(input).release_value_but_fixme_should_propagate_errors().to_deprecated_string();
+    m_decoded_input = decoder->to_utf8(input).release_value_but_fixme_should_propagate_errors().to_byte_string();
     m_utf8_view = Utf8View(m_decoded_input);
     m_utf8_iterator = m_utf8_view.begin();
     m_prev_utf8_iterator = m_utf8_view.begin();
@@ -2808,7 +2808,7 @@ void HTMLTokenizer::insert_input_at_insertion_point(StringView input)
     builder.append(m_decoded_input.substring(0, m_insertion_point.position));
     builder.append(input);
     builder.append(m_decoded_input.substring(m_insertion_point.position));
-    m_decoded_input = builder.to_deprecated_string();
+    m_decoded_input = builder.to_byte_string();
 
     m_utf8_view = Utf8View(m_decoded_input);
     m_utf8_iterator = m_utf8_view.iterator_at_byte_offset(utf8_iterator_byte_offset);
diff --git a/Userland/Libraries/LibWeb/HTML/Parser/HTMLTokenizer.h b/Userland/Libraries/LibWeb/HTML/Parser/HTMLTokenizer.h
index c4619e86ad7..f7364b8cd9b 100644
--- a/Userland/Libraries/LibWeb/HTML/Parser/HTMLTokenizer.h
+++ b/Userland/Libraries/LibWeb/HTML/Parser/HTMLTokenizer.h
@@ -103,7 +103,7 @@ namespace Web::HTML {
 class HTMLTokenizer {
 public:
     explicit HTMLTokenizer();
-    explicit HTMLTokenizer(StringView input, DeprecatedString const& encoding);
+    explicit HTMLTokenizer(StringView input, ByteString const& encoding);
 
     enum class State {
 #define __ENUMERATE_TOKENIZER_STATE(state) state,
@@ -124,7 +124,7 @@ public:
     void set_blocked(bool b) { m_blocked = b; }
     bool is_blocked() const { return m_blocked; }
 
-    DeprecatedString source() const { return m_decoded_input; }
+    ByteString source() const { return m_decoded_input; }
 
     void insert_input_at_insertion_point(StringView input);
     void insert_eof();
@@ -184,7 +184,7 @@ private:
 
     Vector<u32> m_temporary_buffer;
 
-    DeprecatedString m_decoded_input;
+    ByteString m_decoded_input;
 
     struct InsertionPoint {
         size_t position { 0 };
@@ -200,7 +200,7 @@ private:
     HTMLToken m_current_token;
     StringBuilder m_current_builder;
 
-    Optional<DeprecatedString> m_last_emitted_start_tag_name;
+    Optional<ByteString> m_last_emitted_start_tag_name;
 
     bool m_explicit_eof_inserted { false };
     bool m_has_emitted_eof { false };
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.cpp
index 2f498a10ad7..a0e16584b1d 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.cpp
@@ -18,7 +18,7 @@ namespace Web::HTML {
 JS_DEFINE_ALLOCATOR(ClassicScript);
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#creating-a-classic-script
-JS::NonnullGCPtr<ClassicScript> ClassicScript::create(DeprecatedString filename, StringView source, EnvironmentSettingsObject& environment_settings_object, AK::URL base_url, size_t source_line_number, MutedErrors muted_errors)
+JS::NonnullGCPtr<ClassicScript> ClassicScript::create(ByteString filename, StringView source, EnvironmentSettingsObject& environment_settings_object, AK::URL base_url, size_t source_line_number, MutedErrors muted_errors)
 {
     auto& vm = environment_settings_object.realm().vm();
 
@@ -56,7 +56,7 @@ JS::NonnullGCPtr<ClassicScript> ClassicScript::create(DeprecatedString filename,
     // 11. If result is a list of errors, then:
     if (result.is_error()) {
         auto& parse_error = result.error().first();
-        dbgln_if(HTML_SCRIPT_DEBUG, "ClassicScript: Failed to parse: {}", parse_error.to_deprecated_string());
+        dbgln_if(HTML_SCRIPT_DEBUG, "ClassicScript: Failed to parse: {}", parse_error.to_byte_string());
 
         // 1. Set script's parse error and its error to rethrow to result[0].
         script->set_parse_error(JS::SyntaxError::create(environment_settings_object.realm(), parse_error.to_string().release_value_but_fixme_should_propagate_errors()));
@@ -147,7 +147,7 @@ JS::Completion ClassicScript::run(RethrowErrors rethrow_errors, JS::GCPtr<JS::En
     //            Return Completion { [[Type]]: throw, [[Value]]: a new "QuotaExceededError" DOMException, [[Target]]: empty }.
 }
 
-ClassicScript::ClassicScript(AK::URL base_url, DeprecatedString filename, EnvironmentSettingsObject& environment_settings_object)
+ClassicScript::ClassicScript(AK::URL base_url, ByteString filename, EnvironmentSettingsObject& environment_settings_object)
     : Script(move(base_url), move(filename), environment_settings_object)
 {
 }
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.h b/Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.h
index 8935baece9f..38a658873f1 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.h
@@ -24,7 +24,7 @@ public:
         No,
         Yes,
     };
-    static JS::NonnullGCPtr<ClassicScript> create(DeprecatedString filename, StringView source, EnvironmentSettingsObject&, AK::URL base_url, size_t source_line_number = 1, MutedErrors = MutedErrors::No);
+    static JS::NonnullGCPtr<ClassicScript> create(ByteString filename, StringView source, EnvironmentSettingsObject&, AK::URL base_url, size_t source_line_number = 1, MutedErrors = MutedErrors::No);
 
     JS::Script* script_record() { return m_script_record; }
     JS::Script const* script_record() const { return m_script_record; }
@@ -38,7 +38,7 @@ public:
     MutedErrors muted_errors() const { return m_muted_errors; }
 
 private:
-    ClassicScript(AK::URL base_url, DeprecatedString filename, EnvironmentSettingsObject& environment_settings_object);
+    ClassicScript(AK::URL base_url, ByteString filename, EnvironmentSettingsObject& environment_settings_object);
 
     virtual void visit_edges(Cell::Visitor&) override;
 
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp
index 4d7635bb2c9..117b9c5861d 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp
@@ -308,7 +308,7 @@ bool EnvironmentSettingsObject::is_scripting_disabled() const
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#module-type-allowed
-bool EnvironmentSettingsObject::module_type_allowed(AK::DeprecatedString const& module_type) const
+bool EnvironmentSettingsObject::module_type_allowed(AK::ByteString const& module_type) const
 {
     // 1. If moduleType is not "javascript", "css", or "json", then return false.
     if (module_type != "javascript"sv && module_type != "css"sv && module_type != "json"sv)
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.h b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.h
index eba3946dbaf..28d7800cd33 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/Environments.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/Environments.h
@@ -20,7 +20,7 @@ struct Environment {
     virtual ~Environment() = default;
 
     // An id https://html.spec.whatwg.org/multipage/webappapis.html#concept-environment-id
-    DeprecatedString id;
+    ByteString id;
 
     // https://html.spec.whatwg.org/multipage/webappapis.html#concept-environment-creation-url
     AK::URL creation_url;
@@ -69,7 +69,7 @@ struct EnvironmentSettingsObject
     virtual JS::GCPtr<DOM::Document> responsible_document() = 0;
 
     // https://html.spec.whatwg.org/multipage/webappapis.html#api-url-character-encoding
-    virtual DeprecatedString api_url_character_encoding() = 0;
+    virtual ByteString api_url_character_encoding() = 0;
 
     // https://html.spec.whatwg.org/multipage/webappapis.html#api-base-url
     virtual AK::URL api_base_url() = 0;
@@ -111,7 +111,7 @@ struct EnvironmentSettingsObject
     bool is_scripting_enabled() const;
     bool is_scripting_disabled() const;
 
-    bool module_type_allowed(DeprecatedString const& module_type) const;
+    bool module_type_allowed(ByteString const& module_type) const;
 
     void disallow_further_import_maps();
 
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/Fetching.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/Fetching.cpp
index 8a65efd4d3e..55956ceea5b 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/Fetching.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/Fetching.cpp
@@ -54,10 +54,10 @@ ScriptFetchOptions default_classic_script_fetch_options()
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#module-type-from-module-request
-DeprecatedString module_type_from_module_request(JS::ModuleRequest const& module_request)
+ByteString module_type_from_module_request(JS::ModuleRequest const& module_request)
 {
     // 1. Let moduleType be "javascript".
-    DeprecatedString module_type = "javascript"sv;
+    ByteString module_type = "javascript"sv;
 
     // 2. If moduleRequest.[[Attributes]] has a Record entry such that entry.[[Key]] is "type", then:
     for (auto const& entry : module_request.attributes) {
@@ -77,7 +77,7 @@ DeprecatedString module_type_from_module_request(JS::ModuleRequest const& module
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#resolve-a-module-specifier
-WebIDL::ExceptionOr<AK::URL> resolve_module_specifier(Optional<Script&> referring_script, DeprecatedString const& specifier)
+WebIDL::ExceptionOr<AK::URL> resolve_module_specifier(Optional<Script&> referring_script, ByteString const& specifier)
 {
     // 1. Let settingsObject and baseURL be null.
     Optional<EnvironmentSettingsObject&> settings_object;
@@ -153,7 +153,7 @@ WebIDL::ExceptionOr<AK::URL> resolve_module_specifier(Optional<Script&> referrin
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#resolving-an-imports-match
-WebIDL::ExceptionOr<Optional<AK::URL>> resolve_imports_match(DeprecatedString const& normalized_specifier, Optional<AK::URL> as_url, ModuleSpecifierMap const& specifier_map)
+WebIDL::ExceptionOr<Optional<AK::URL>> resolve_imports_match(ByteString const& normalized_specifier, Optional<AK::URL> as_url, ModuleSpecifierMap const& specifier_map)
 {
     // 1. For each specifierKey → resolutionResult of specifierMap:
     for (auto const& [specifier_key, resolution_result] : specifier_map) {
@@ -220,7 +220,7 @@ WebIDL::ExceptionOr<Optional<AK::URL>> resolve_imports_match(DeprecatedString co
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#resolving-a-url-like-module-specifier
-Optional<AK::URL> resolve_url_like_module_specifier(DeprecatedString const& specifier, AK::URL const& base_url)
+Optional<AK::URL> resolve_url_like_module_specifier(ByteString const& specifier, AK::URL const& base_url)
 {
     // 1. If specifier starts with "/", "./", or "../", then:
     if (specifier.starts_with("/"sv) || specifier.starts_with("./"sv) || specifier.starts_with("../"sv)) {
@@ -331,7 +331,7 @@ WebIDL::ExceptionOr<void> fetch_classic_script(JS::NonnullGCPtr<HTMLScriptElemen
         //    options, and muted errors.
         // FIXME: Pass options.
         auto response_url = response->url().value_or({});
-        auto script = ClassicScript::create(response_url.to_deprecated_string(), source_text, settings_object, response_url, 1, muted_errors);
+        auto script = ClassicScript::create(response_url.to_byte_string(), source_text, settings_object, response_url, 1, muted_errors);
 
         // 8. Run onComplete given script.
         on_complete->function()(script);
@@ -401,7 +401,7 @@ WebIDL::ExceptionOr<void> fetch_classic_worker_script(AK::URL const& url, Enviro
         // 5. Let script be the result of creating a classic script using sourceText, settingsObject,
         //    response's URL, and the default classic script fetch options.
         auto response_url = response->url().value_or({});
-        auto script = ClassicScript::create(response_url.to_deprecated_string(), source_text, settings_object, response_url);
+        auto script = ClassicScript::create(response_url.to_byte_string(), source_text, settings_object, response_url);
 
         // 6. Run onComplete given script.
         on_complete->function()(script);
@@ -562,7 +562,7 @@ void fetch_single_module_script(JS::Realm& realm,
     OnFetchScriptComplete on_complete)
 {
     // 1. Let moduleType be "javascript".
-    DeprecatedString module_type = "javascript"sv;
+    ByteString module_type = "javascript"sv;
 
     // 2. If moduleRequest was given, then set moduleType to the result of running the module type from module request steps given moduleRequest.
     if (module_request.has_value())
@@ -688,7 +688,7 @@ void fetch_external_module_script_graph(JS::Realm& realm, AK::URL const& url, En
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#fetch-an-inline-module-script-graph
-void fetch_inline_module_script_graph(JS::Realm& realm, DeprecatedString const& filename, DeprecatedString const& source_text, AK::URL const& base_url, EnvironmentSettingsObject& settings_object, OnFetchScriptComplete on_complete)
+void fetch_inline_module_script_graph(JS::Realm& realm, ByteString const& filename, ByteString const& source_text, AK::URL const& base_url, EnvironmentSettingsObject& settings_object, OnFetchScriptComplete on_complete)
 {
     // 1. Disallow further import maps given settingsObject.
     settings_object.disallow_further_import_maps();
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/Fetching.h b/Userland/Libraries/LibWeb/HTML/Scripting/Fetching.h
index 5abd2a0b95b..364e0e4a042 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/Fetching.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/Fetching.h
@@ -81,16 +81,16 @@ private:
     }
 };
 
-DeprecatedString module_type_from_module_request(JS::ModuleRequest const&);
-WebIDL::ExceptionOr<AK::URL> resolve_module_specifier(Optional<Script&> referring_script, DeprecatedString const& specifier);
-WebIDL::ExceptionOr<Optional<AK::URL>> resolve_imports_match(DeprecatedString const& normalized_specifier, Optional<AK::URL> as_url, ModuleSpecifierMap const&);
-Optional<AK::URL> resolve_url_like_module_specifier(DeprecatedString const& specifier, AK::URL const& base_url);
+ByteString module_type_from_module_request(JS::ModuleRequest const&);
+WebIDL::ExceptionOr<AK::URL> resolve_module_specifier(Optional<Script&> referring_script, ByteString const& specifier);
+WebIDL::ExceptionOr<Optional<AK::URL>> resolve_imports_match(ByteString const& normalized_specifier, Optional<AK::URL> as_url, ModuleSpecifierMap const&);
+Optional<AK::URL> resolve_url_like_module_specifier(ByteString const& specifier, AK::URL const& base_url);
 
 WebIDL::ExceptionOr<void> fetch_classic_script(JS::NonnullGCPtr<HTMLScriptElement>, AK::URL const&, EnvironmentSettingsObject& settings_object, ScriptFetchOptions options, CORSSettingAttribute cors_setting, String character_encoding, OnFetchScriptComplete on_complete);
 WebIDL::ExceptionOr<void> fetch_classic_worker_script(AK::URL const&, EnvironmentSettingsObject& fetch_client, Fetch::Infrastructure::Request::Destination, EnvironmentSettingsObject& settings_object, PerformTheFetchHook, OnFetchScriptComplete);
 void fetch_internal_module_script_graph(JS::Realm&, JS::ModuleRequest const& module_request, EnvironmentSettingsObject& fetch_client_settings_object, Fetch::Infrastructure::Request::Destination, ScriptFetchOptions const&, Script& referring_script, HashTable<ModuleLocationTuple> const& visited_set, OnFetchScriptComplete on_complete);
 void fetch_external_module_script_graph(JS::Realm&, AK::URL const&, EnvironmentSettingsObject& settings_object, ScriptFetchOptions const&, OnFetchScriptComplete on_complete);
-void fetch_inline_module_script_graph(JS::Realm&, DeprecatedString const& filename, DeprecatedString const& source_text, AK::URL const& base_url, EnvironmentSettingsObject& settings_object, OnFetchScriptComplete on_complete);
+void fetch_inline_module_script_graph(JS::Realm&, ByteString const& filename, ByteString const& source_text, AK::URL const& base_url, EnvironmentSettingsObject& settings_object, OnFetchScriptComplete on_complete);
 void fetch_single_imported_module_script(JS::Realm&, AK::URL const&, EnvironmentSettingsObject& fetch_client, Fetch::Infrastructure::Request::Destination, ScriptFetchOptions const&, EnvironmentSettingsObject& settings_object, Fetch::Infrastructure::Request::Referrer, JS::ModuleRequest const&, OnFetchScriptComplete on_complete);
 
 void fetch_descendants_of_a_module_script(JS::Realm&, JavaScriptModuleScript& module_script, EnvironmentSettingsObject& fetch_client_settings_object, Fetch::Infrastructure::Request::Destination, HashTable<ModuleLocationTuple> visited_set, OnFetchScriptComplete callback);
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/ImportMap.h b/Userland/Libraries/LibWeb/HTML/Scripting/ImportMap.h
index 63267d6ae02..463d9e5e068 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/ImportMap.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/ImportMap.h
@@ -10,7 +10,7 @@
 
 namespace Web::HTML {
 
-using ModuleSpecifierMap = HashMap<DeprecatedString, Optional<AK::URL>>;
+using ModuleSpecifierMap = HashMap<ByteString, Optional<AK::URL>>;
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#import-map
 class ImportMap {
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/ModuleMap.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/ModuleMap.cpp
index 655094f32e9..7a11fe8018a 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/ModuleMap.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/ModuleMap.cpp
@@ -21,17 +21,17 @@ void ModuleMap::visit_edges(Visitor& visitor)
             visitor.visit(callback);
 }
 
-bool ModuleMap::is_fetching(AK::URL const& url, DeprecatedString const& type) const
+bool ModuleMap::is_fetching(AK::URL const& url, ByteString const& type) const
 {
     return is(url, type, EntryType::Fetching);
 }
 
-bool ModuleMap::is_failed(AK::URL const& url, DeprecatedString const& type) const
+bool ModuleMap::is_failed(AK::URL const& url, ByteString const& type) const
 {
     return is(url, type, EntryType::Failed);
 }
 
-bool ModuleMap::is(AK::URL const& url, DeprecatedString const& type, EntryType entry_type) const
+bool ModuleMap::is(AK::URL const& url, ByteString const& type, EntryType entry_type) const
 {
     auto value = m_values.get({ url, type });
     if (!value.has_value())
@@ -40,12 +40,12 @@ bool ModuleMap::is(AK::URL const& url, DeprecatedString const& type, EntryType e
     return value->type == entry_type;
 }
 
-Optional<ModuleMap::Entry> ModuleMap::get(AK::URL const& url, DeprecatedString const& type) const
+Optional<ModuleMap::Entry> ModuleMap::get(AK::URL const& url, ByteString const& type) const
 {
     return m_values.get({ url, type });
 }
 
-AK::HashSetResult ModuleMap::set(AK::URL const& url, DeprecatedString const& type, Entry entry)
+AK::HashSetResult ModuleMap::set(AK::URL const& url, ByteString const& type, Entry entry)
 {
     // NOTE: Re-entering this function while firing wait_for_change callbacks is not allowed.
     VERIFY(!m_firing_callbacks);
@@ -63,7 +63,7 @@ AK::HashSetResult ModuleMap::set(AK::URL const& url, DeprecatedString const& typ
     return value;
 }
 
-void ModuleMap::wait_for_change(JS::Heap& heap, AK::URL const& url, DeprecatedString const& type, Function<void(Entry)> callback)
+void ModuleMap::wait_for_change(JS::Heap& heap, AK::URL const& url, ByteString const& type, Function<void(Entry)> callback)
 {
     m_callbacks.ensure({ url, type }).append(JS::create_heap_function(heap, move(callback)));
 }
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/ModuleMap.h b/Userland/Libraries/LibWeb/HTML/Scripting/ModuleMap.h
index 3a699978543..5b9a0fc9e39 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/ModuleMap.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/ModuleMap.h
@@ -15,14 +15,14 @@ namespace Web::HTML {
 
 class ModuleLocationTuple {
 public:
-    ModuleLocationTuple(AK::URL url, DeprecatedString type)
+    ModuleLocationTuple(AK::URL url, ByteString type)
         : m_url(move(url))
         , m_type(move(type))
     {
     }
 
     AK::URL const& url() const { return m_url; }
-    DeprecatedString const& type() const { return m_type; }
+    ByteString const& type() const { return m_type; }
 
     bool operator==(ModuleLocationTuple const& other) const
     {
@@ -31,7 +31,7 @@ public:
 
 private:
     AK::URL m_url;
-    DeprecatedString m_type;
+    ByteString m_type;
 };
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#module-map
@@ -56,16 +56,16 @@ public:
 
     using CallbackFunction = JS::NonnullGCPtr<JS::HeapFunction<void(Entry)>>;
 
-    bool is_fetching(AK::URL const& url, DeprecatedString const& type) const;
-    bool is_failed(AK::URL const& url, DeprecatedString const& type) const;
+    bool is_fetching(AK::URL const& url, ByteString const& type) const;
+    bool is_failed(AK::URL const& url, ByteString const& type) const;
 
-    bool is(AK::URL const& url, DeprecatedString const& type, EntryType) const;
+    bool is(AK::URL const& url, ByteString const& type, EntryType) const;
 
-    Optional<Entry> get(AK::URL const& url, DeprecatedString const& type) const;
+    Optional<Entry> get(AK::URL const& url, ByteString const& type) const;
 
-    AK::HashSetResult set(AK::URL const& url, DeprecatedString const& type, Entry);
+    AK::HashSetResult set(AK::URL const& url, ByteString const& type, Entry);
 
-    void wait_for_change(JS::Heap&, AK::URL const& url, DeprecatedString const& type, Function<void(Entry)> callback);
+    void wait_for_change(JS::Heap&, AK::URL const& url, ByteString const& type, Function<void(Entry)> callback);
 
 private:
     virtual void visit_edges(JS::Cell::Visitor&) override;
@@ -84,7 +84,7 @@ template<>
 struct Traits<Web::HTML::ModuleLocationTuple> : public DefaultTraits<Web::HTML::ModuleLocationTuple> {
     static unsigned hash(Web::HTML::ModuleLocationTuple const& tuple)
     {
-        return pair_int_hash(tuple.url().to_deprecated_string().hash(), tuple.type().hash());
+        return pair_int_hash(tuple.url().to_byte_string().hash(), tuple.type().hash());
     }
 };
 
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/ModuleScript.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/ModuleScript.cpp
index 8bc2cc9cd83..f78fd134476 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/ModuleScript.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/ModuleScript.cpp
@@ -17,20 +17,20 @@ JS_DEFINE_ALLOCATOR(JavaScriptModuleScript);
 
 ModuleScript::~ModuleScript() = default;
 
-ModuleScript::ModuleScript(AK::URL base_url, DeprecatedString filename, EnvironmentSettingsObject& environment_settings_object)
+ModuleScript::ModuleScript(AK::URL base_url, ByteString filename, EnvironmentSettingsObject& environment_settings_object)
     : Script(move(base_url), move(filename), environment_settings_object)
 {
 }
 
 JavaScriptModuleScript::~JavaScriptModuleScript() = default;
 
-JavaScriptModuleScript::JavaScriptModuleScript(AK::URL base_url, DeprecatedString filename, EnvironmentSettingsObject& environment_settings_object)
+JavaScriptModuleScript::JavaScriptModuleScript(AK::URL base_url, ByteString filename, EnvironmentSettingsObject& environment_settings_object)
     : ModuleScript(move(base_url), move(filename), environment_settings_object)
 {
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#creating-a-javascript-module-script
-WebIDL::ExceptionOr<JS::GCPtr<JavaScriptModuleScript>> JavaScriptModuleScript::create(DeprecatedString const& filename, StringView source, EnvironmentSettingsObject& settings_object, AK::URL base_url)
+WebIDL::ExceptionOr<JS::GCPtr<JavaScriptModuleScript>> JavaScriptModuleScript::create(ByteString const& filename, StringView source, EnvironmentSettingsObject& settings_object, AK::URL base_url)
 {
     // 1. If scripting is disabled for settings, then set source to the empty string.
     if (settings_object.is_scripting_disabled())
@@ -59,7 +59,7 @@ WebIDL::ExceptionOr<JS::GCPtr<JavaScriptModuleScript>> JavaScriptModuleScript::c
     // 8. If result is a list of errors, then:
     if (result.is_error()) {
         auto& parse_error = result.error().first();
-        dbgln("JavaScriptModuleScript: Failed to parse: {}", parse_error.to_deprecated_string());
+        dbgln("JavaScriptModuleScript: Failed to parse: {}", parse_error.to_byte_string());
 
         // 1. Set script's parse error to result[0].
         script->set_parse_error(JS::SyntaxError::create(settings_object.realm(), parse_error.to_string().release_value_but_fixme_should_propagate_errors()));
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/ModuleScript.h b/Userland/Libraries/LibWeb/HTML/Scripting/ModuleScript.h
index b2a42373e22..2d2b51a6185 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/ModuleScript.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/ModuleScript.h
@@ -19,7 +19,7 @@ public:
     virtual ~ModuleScript() override;
 
 protected:
-    ModuleScript(AK::URL base_url, DeprecatedString filename, EnvironmentSettingsObject& environment_settings_object);
+    ModuleScript(AK::URL base_url, ByteString filename, EnvironmentSettingsObject& environment_settings_object);
 };
 
 class JavaScriptModuleScript final : public ModuleScript {
@@ -29,7 +29,7 @@ class JavaScriptModuleScript final : public ModuleScript {
 public:
     virtual ~JavaScriptModuleScript() override;
 
-    static WebIDL::ExceptionOr<JS::GCPtr<JavaScriptModuleScript>> create(DeprecatedString const& filename, StringView source, EnvironmentSettingsObject&, AK::URL base_url);
+    static WebIDL::ExceptionOr<JS::GCPtr<JavaScriptModuleScript>> create(ByteString const& filename, StringView source, EnvironmentSettingsObject&, AK::URL base_url);
 
     enum class PreventErrorReporting {
         Yes,
@@ -42,7 +42,7 @@ public:
     JS::SourceTextModule* record() { return m_record.ptr(); }
 
 protected:
-    JavaScriptModuleScript(AK::URL base_url, DeprecatedString filename, EnvironmentSettingsObject& environment_settings_object);
+    JavaScriptModuleScript(AK::URL base_url, ByteString filename, EnvironmentSettingsObject& environment_settings_object);
 
 private:
     virtual void visit_edges(JS::Cell::Visitor&) override;
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/Script.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/Script.cpp
index 4f1fae97bc7..187a0919965 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/Script.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/Script.cpp
@@ -11,7 +11,7 @@ namespace Web::HTML {
 
 JS_DEFINE_ALLOCATOR(Script);
 
-Script::Script(AK::URL base_url, DeprecatedString filename, EnvironmentSettingsObject& environment_settings_object)
+Script::Script(AK::URL base_url, ByteString filename, EnvironmentSettingsObject& environment_settings_object)
     : m_base_url(move(base_url))
     , m_filename(move(filename))
     , m_settings_object(environment_settings_object)
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/Script.h b/Userland/Libraries/LibWeb/HTML/Scripting/Script.h
index dd8a042bc28..d66d8c8a8aa 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/Script.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/Script.h
@@ -24,7 +24,7 @@ public:
     virtual ~Script() override;
 
     AK::URL const& base_url() const { return m_base_url; }
-    DeprecatedString const& filename() const { return m_filename; }
+    ByteString const& filename() const { return m_filename; }
 
     EnvironmentSettingsObject& settings_object() { return m_settings_object; }
 
@@ -35,7 +35,7 @@ public:
     void set_parse_error(JS::Value value) { m_parse_error = value; }
 
 protected:
-    Script(AK::URL base_url, DeprecatedString filename, EnvironmentSettingsObject& environment_settings_object);
+    Script(AK::URL base_url, ByteString filename, EnvironmentSettingsObject& environment_settings_object);
 
     virtual void visit_edges(Visitor&) override;
 
@@ -43,7 +43,7 @@ private:
     virtual void visit_host_defined_self(JS::Cell::Visitor&) override;
 
     AK::URL m_base_url;
-    DeprecatedString m_filename;
+    ByteString m_filename;
     JS::NonnullGCPtr<EnvironmentSettingsObject> m_settings_object;
 
     // https://html.spec.whatwg.org/multipage/webappapis.html#concept-script-parse-error
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.cpp b/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.cpp
index b2e73abc4a2..4d3a7672337 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.cpp
@@ -51,7 +51,7 @@ void WindowEnvironmentSettingsObject::setup(Page& page, AK::URL const& creation_
         settings_object->target_browsing_context = reserved_environment->target_browsing_context;
 
         // 2. Set reservedEnvironment's id to the empty string.
-        reserved_environment->id = DeprecatedString::empty();
+        reserved_environment->id = ByteString::empty();
     }
 
     // 5. Otherwise, ...
@@ -60,7 +60,7 @@ void WindowEnvironmentSettingsObject::setup(Page& page, AK::URL const& creation_
         //        settings object's target browsing context to null,
         //        and settings object's active service worker to null.
         static i64 next_id = 1;
-        settings_object->id = DeprecatedString::number(next_id++);
+        settings_object->id = ByteString::number(next_id++);
         settings_object->target_browsing_context = nullptr;
     }
 
@@ -90,10 +90,10 @@ JS::GCPtr<DOM::Document> WindowEnvironmentSettingsObject::responsible_document()
 }
 
 // https://html.spec.whatwg.org/multipage/window-object.html#script-settings-for-window-objects:api-url-character-encoding
-DeprecatedString WindowEnvironmentSettingsObject::api_url_character_encoding()
+ByteString WindowEnvironmentSettingsObject::api_url_character_encoding()
 {
     // Return the current character encoding of window's associated Document.
-    return m_window->associated_document().encoding_or_default().to_deprecated_string();
+    return m_window->associated_document().encoding_or_default().to_byte_string();
 }
 
 // https://html.spec.whatwg.org/multipage/window-object.html#script-settings-for-window-objects:api-base-url
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.h b/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.h
index 5cc0a04a26a..8a66e1b165a 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/WindowEnvironmentSettingsObject.h
@@ -21,7 +21,7 @@ public:
     virtual ~WindowEnvironmentSettingsObject() override;
 
     virtual JS::GCPtr<DOM::Document> responsible_document() override;
-    virtual DeprecatedString api_url_character_encoding() override;
+    virtual ByteString api_url_character_encoding() override;
     virtual AK::URL api_base_url() override;
     virtual Origin origin() override;
     virtual PolicyContainer policy_container() override;
diff --git a/Userland/Libraries/LibWeb/HTML/Scripting/WorkerEnvironmentSettingsObject.h b/Userland/Libraries/LibWeb/HTML/Scripting/WorkerEnvironmentSettingsObject.h
index 2b7957f048c..d35fd468e36 100644
--- a/Userland/Libraries/LibWeb/HTML/Scripting/WorkerEnvironmentSettingsObject.h
+++ b/Userland/Libraries/LibWeb/HTML/Scripting/WorkerEnvironmentSettingsObject.h
@@ -29,7 +29,7 @@ public:
     virtual ~WorkerEnvironmentSettingsObject() override = default;
 
     JS::GCPtr<DOM::Document> responsible_document() override { return nullptr; }
-    DeprecatedString api_url_character_encoding() override { return m_api_url_character_encoding; }
+    ByteString api_url_character_encoding() override { return m_api_url_character_encoding; }
     AK::URL api_base_url() override { return m_url; }
     Origin origin() override { return m_origin; }
     PolicyContainer policy_container() override { return m_policy_container; }
@@ -38,7 +38,7 @@ public:
 private:
     virtual void visit_edges(JS::Cell::Visitor&) override;
 
-    DeprecatedString m_api_url_character_encoding;
+    ByteString m_api_url_character_encoding;
     AK::URL m_url;
     HTML::Origin m_origin;
     HTML::PolicyContainer m_policy_container;
diff --git a/Userland/Libraries/LibWeb/HTML/SessionHistoryEntry.h b/Userland/Libraries/LibWeb/HTML/SessionHistoryEntry.h
index 0c9feb4f3da..b663d452cb9 100644
--- a/Userland/Libraries/LibWeb/HTML/SessionHistoryEntry.h
+++ b/Userland/Libraries/LibWeb/HTML/SessionHistoryEntry.h
@@ -78,7 +78,7 @@ struct SessionHistoryEntry final : public JS::Cell {
     // FIXME: scroll position data, which is scroll position data for the document's restorable scrollable regions
 
     // browsing context name, a browsing context name or null, initially null
-    Optional<DeprecatedString> browsing_context_name;
+    Optional<ByteString> browsing_context_name;
 
     // https://html.spec.whatwg.org/multipage/browsing-the-web.html#she-other
     // FIXME: persisted user state, which is implementation-defined, initially null
diff --git a/Userland/Libraries/LibWeb/HTML/StructuredSerialize.cpp b/Userland/Libraries/LibWeb/HTML/StructuredSerialize.cpp
index 2d5a4fe682d..3b97aef77d2 100644
--- a/Userland/Libraries/LibWeb/HTML/StructuredSerialize.cpp
+++ b/Userland/Libraries/LibWeb/HTML/StructuredSerialize.cpp
@@ -231,8 +231,8 @@ public:
             // Note: A Regex<ECMA262> object is perfectly happy to be reconstructed with just the source+flags
             //       In the future, we could optimize the work being done on the deserialize step by serializing
             //       more of the internal state (the [[RegExpMatcher]] internal slot)
-            TRY(serialize_string(m_serialized, TRY_OR_THROW_OOM(m_vm, String::from_deprecated_string(regexp_object.pattern()))));
-            TRY(serialize_string(m_serialized, TRY_OR_THROW_OOM(m_vm, String::from_deprecated_string(regexp_object.flags()))));
+            TRY(serialize_string(m_serialized, TRY_OR_THROW_OOM(m_vm, String::from_byte_string(regexp_object.pattern()))));
+            TRY(serialize_string(m_serialized, TRY_OR_THROW_OOM(m_vm, String::from_byte_string(regexp_object.flags()))));
         }
 
         // 13. Otherwise, if value has an [[ArrayBufferData]] internal slot, then:
@@ -847,7 +847,7 @@ public:
                     auto deserialized_value = TRY(deserialize());
 
                     // 2. Let result be ! CreateDataProperty(value, entry.[[Key]], deserializedValue).
-                    auto result = MUST(object.create_data_property(key.to_deprecated_string(), deserialized_value));
+                    auto result = MUST(object.create_data_property(key.to_byte_string(), deserialized_value));
 
                     // 3. Assert: result is true.
                     VERIFY(result);
diff --git a/Userland/Libraries/LibWeb/HTML/Window.cpp b/Userland/Libraries/LibWeb/HTML/Window.cpp
index 9cc191ad9b1..a84dc1d7529 100644
--- a/Userland/Libraries/LibWeb/HTML/Window.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Window.cpp
@@ -7,7 +7,7 @@
  */
 
 #include <AK/Base64.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/GenericLexer.h>
 #include <AK/Utf8View.h>
 #include <LibIPC/File.h>
@@ -165,10 +165,10 @@ static StringView normalize_feature_name(StringView name)
 }
 
 // https://html.spec.whatwg.org/multipage/nav-history-apis.html#concept-window-open-features-tokenize
-static OrderedHashMap<DeprecatedString, DeprecatedString> tokenize_open_features(StringView features)
+static OrderedHashMap<ByteString, ByteString> tokenize_open_features(StringView features)
 {
     // 1. Let tokenizedFeatures be a new ordered map.
-    OrderedHashMap<DeprecatedString, DeprecatedString> tokenized_features;
+    OrderedHashMap<ByteString, ByteString> tokenized_features;
 
     // 2. Let position point at the first code point of features.
     GenericLexer lexer(features);
@@ -181,10 +181,10 @@ static OrderedHashMap<DeprecatedString, DeprecatedString> tokenize_open_features
     // 3. While position is not past the end of features:
     while (!lexer.is_eof()) {
         // 1. Let name be the empty string.
-        DeprecatedString name;
+        ByteString name;
 
         // 2. Let value be the empty string.
-        DeprecatedString value;
+        ByteString value;
 
         // 3. Collect a sequence of code points that are feature separators from features given position. This skips past leading separators before the name.
         lexer.ignore_while(is_feature_separator);
@@ -246,7 +246,7 @@ static T parse_boolean_feature(StringView value)
 }
 
 //  https://html.spec.whatwg.org/multipage/window-object.html#popup-window-is-requested
-static TokenizedFeature::Popup check_if_a_popup_window_is_requested(OrderedHashMap<DeprecatedString, DeprecatedString> const& tokenized_features)
+static TokenizedFeature::Popup check_if_a_popup_window_is_requested(OrderedHashMap<ByteString, ByteString> const& tokenized_features)
 {
     // 1. If tokenizedFeatures is empty, then return false.
     if (tokenized_features.is_empty())
@@ -1078,7 +1078,7 @@ WebIDL::ExceptionOr<void> Window::window_post_message_steps(JS::Value message, W
         // with the origin attribute initialized to origin and the source attribute initialized to source, and then return.
         if (deserialize_record_or_error.is_exception()) {
             MessageEventInit message_event_init {};
-            message_event_init.origin = MUST(String::from_deprecated_string(origin));
+            message_event_init.origin = MUST(String::from_byte_string(origin));
             message_event_init.source = JS::make_handle(source);
 
             auto message_error_event = MessageEvent::create(target_realm, EventNames::messageerror, message_event_init);
@@ -1104,7 +1104,7 @@ WebIDL::ExceptionOr<void> Window::window_post_message_steps(JS::Value message, W
         //    the source attribute initialized to source, the data attribute initialized to messageClone, and the ports attribute
         //    initialized to newPorts.
         MessageEventInit message_event_init {};
-        message_event_init.origin = MUST(String::from_deprecated_string(origin));
+        message_event_init.origin = MUST(String::from_byte_string(origin));
         message_event_init.source = JS::make_handle(source);
         message_event_init.data = message_clone;
         message_event_init.ports = move(new_ports);
diff --git a/Userland/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp b/Userland/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp
index 536936b4eec..bca8068f4dc 100644
--- a/Userland/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp
+++ b/Userland/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp
@@ -70,7 +70,7 @@ WebIDL::ExceptionOr<String> WindowOrWorkerGlobalScopeMixin::origin() const
     auto& vm = this_impl().vm();
 
     // The origin getter steps are to return this's relevant settings object's origin, serialized.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(relevant_settings_object(this_impl()).origin().serialize()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(relevant_settings_object(this_impl()).origin().serialize()));
 }
 
 // https://html.spec.whatwg.org/multipage/webappapis.html#dom-issecurecontext
diff --git a/Userland/Libraries/LibWeb/HTML/WindowProxy.cpp b/Userland/Libraries/LibWeb/HTML/WindowProxy.cpp
index 7dfd310ff88..61f99aec427 100644
--- a/Userland/Libraries/LibWeb/HTML/WindowProxy.cpp
+++ b/Userland/Libraries/LibWeb/HTML/WindowProxy.cpp
@@ -241,7 +241,7 @@ JS::ThrowCompletionOr<JS::MarkedVector<JS::Value>> WindowProxy::internal_own_pro
     // 5. Repeat while index < maxProperties,
     for (size_t i = 0; i < max_properties; ++i) {
         // 1. Add ! ToString(index) as the last element of keys.
-        keys.append(JS::PrimitiveString::create(vm, DeprecatedString::number(i)));
+        keys.append(JS::PrimitiveString::create(vm, ByteString::number(i)));
 
         // 2. Increment index by 1.
     }
diff --git a/Userland/Libraries/LibWeb/HTML/Worker.cpp b/Userland/Libraries/LibWeb/HTML/Worker.cpp
index 70034da7e10..93df48289ad 100644
--- a/Userland/Libraries/LibWeb/HTML/Worker.cpp
+++ b/Userland/Libraries/LibWeb/HTML/Worker.cpp
@@ -61,7 +61,7 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<Worker>> Worker::create(String const& scrip
     auto& outside_settings = document.relevant_settings_object();
 
     // 3. Parse the scriptURL argument relative to outside settings.
-    auto url = document.parse_url(script_url.to_deprecated_string());
+    auto url = document.parse_url(script_url.to_byte_string());
 
     // 4. If this fails, throw a "SyntaxError" DOMException.
     if (!url.is_valid()) {
diff --git a/Userland/Libraries/LibWeb/HTML/WorkerAgent.cpp b/Userland/Libraries/LibWeb/HTML/WorkerAgent.cpp
index efa804192dc..a64b8289c8c 100644
--- a/Userland/Libraries/LibWeb/HTML/WorkerAgent.cpp
+++ b/Userland/Libraries/LibWeb/HTML/WorkerAgent.cpp
@@ -19,7 +19,7 @@ ErrorOr<String> application_directory()
 {
     auto current_executable_path = TRY(Core::System::current_executable_path());
     auto dirname = LexicalPath::dirname(current_executable_path);
-    return String::from_deprecated_string(dirname);
+    return String::from_byte_string(dirname);
 }
 
 ErrorOr<Vector<String>> get_paths_for_helper_process(StringView process_name)
diff --git a/Userland/Libraries/LibWeb/HTML/WorkerLocation.cpp b/Userland/Libraries/LibWeb/HTML/WorkerLocation.cpp
index d2a8fd4a889..5826d5406ed 100644
--- a/Userland/Libraries/LibWeb/HTML/WorkerLocation.cpp
+++ b/Userland/Libraries/LibWeb/HTML/WorkerLocation.cpp
@@ -17,7 +17,7 @@ WebIDL::ExceptionOr<String> WorkerLocation::href() const
 {
     auto& vm = realm().vm();
     // The href getter steps are to return this's WorkerGlobalScope object's url, serialized.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_global_scope->url().serialize()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(m_global_scope->url().serialize()));
 }
 
 // https://html.spec.whatwg.org/multipage/workers.html#dom-workerlocation-origin
@@ -25,7 +25,7 @@ WebIDL::ExceptionOr<String> WorkerLocation::origin() const
 {
     auto& vm = realm().vm();
     // The origin getter steps are to return the serialization of this's WorkerGlobalScope object's url's origin.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_global_scope->url().serialize_origin()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(m_global_scope->url().serialize_origin()));
 }
 
 // https://html.spec.whatwg.org/multipage/workers.html#dom-workerlocation-protocol
@@ -95,7 +95,7 @@ WebIDL::ExceptionOr<String> WorkerLocation::pathname() const
 {
     auto& vm = realm().vm();
     // The pathname getter steps are to return the result of URL path serializing this's WorkerGlobalScope object's url.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_global_scope->url().serialize_path()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(m_global_scope->url().serialize_path()));
 }
 
 // https://html.spec.whatwg.org/multipage/workers.html#dom-workerlocation-search
diff --git a/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.cpp b/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.cpp
index a2db7cc229e..a7686dd461b 100644
--- a/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.cpp
+++ b/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.cpp
@@ -24,25 +24,25 @@ ListItemMarkerBox::ListItemMarkerBox(DOM::Document& document, CSS::ListStyleType
     case CSS::ListStyleType::DisclosureOpen:
         break;
     case CSS::ListStyleType::Decimal:
-        m_text = DeprecatedString::formatted("{}.", m_index);
+        m_text = ByteString::formatted("{}.", m_index);
         break;
     case CSS::ListStyleType::DecimalLeadingZero:
         // This is weird, but in accordance to spec.
-        m_text = m_index < 10 ? DeprecatedString::formatted("0{}.", m_index) : DeprecatedString::formatted("{}.", m_index);
+        m_text = m_index < 10 ? ByteString::formatted("0{}.", m_index) : ByteString::formatted("{}.", m_index);
         break;
     case CSS::ListStyleType::LowerAlpha:
     case CSS::ListStyleType::LowerLatin:
-        m_text = DeprecatedString::bijective_base_from(m_index - 1).to_lowercase();
+        m_text = ByteString::bijective_base_from(m_index - 1).to_lowercase();
         break;
     case CSS::ListStyleType::UpperAlpha:
     case CSS::ListStyleType::UpperLatin:
-        m_text = DeprecatedString::bijective_base_from(m_index - 1);
+        m_text = ByteString::bijective_base_from(m_index - 1);
         break;
     case CSS::ListStyleType::LowerRoman:
-        m_text = DeprecatedString::roman_number_from(m_index).to_lowercase();
+        m_text = ByteString::roman_number_from(m_index).to_lowercase();
         break;
     case CSS::ListStyleType::UpperRoman:
-        m_text = DeprecatedString::roman_number_from(m_index);
+        m_text = ByteString::roman_number_from(m_index);
         break;
     case CSS::ListStyleType::None:
         break;
diff --git a/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.h b/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.h
index f11ed93fc94..aa72b0ead05 100644
--- a/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.h
+++ b/Userland/Libraries/LibWeb/Layout/ListItemMarkerBox.h
@@ -18,7 +18,7 @@ public:
     explicit ListItemMarkerBox(DOM::Document&, CSS::ListStyleType, CSS::ListStylePosition, size_t index, NonnullRefPtr<CSS::StyleProperties>);
     virtual ~ListItemMarkerBox() override;
 
-    Optional<DeprecatedString> const& text() const { return m_text; }
+    Optional<ByteString> const& text() const { return m_text; }
 
     virtual JS::GCPtr<Painting::Paintable> create_paintable() const override;
 
@@ -33,7 +33,7 @@ private:
     CSS::ListStylePosition m_list_style_position { CSS::ListStylePosition::Outside };
     size_t m_index;
 
-    Optional<DeprecatedString> m_text {};
+    Optional<ByteString> m_text {};
 };
 
 template<>
diff --git a/Userland/Libraries/LibWeb/Layout/Node.cpp b/Userland/Libraries/LibWeb/Layout/Node.cpp
index 3130a720ddd..71a94816c35 100644
--- a/Userland/Libraries/LibWeb/Layout/Node.cpp
+++ b/Userland/Libraries/LibWeb/Layout/Node.cpp
@@ -880,7 +880,7 @@ bool Node::is_root_element() const
     return is<HTML::HTMLHtmlElement>(*dom_node());
 }
 
-DeprecatedString Node::debug_description() const
+ByteString Node::debug_description() const
 {
     StringBuilder builder;
     builder.append(class_name());
@@ -896,7 +896,7 @@ DeprecatedString Node::debug_description() const
     } else {
         builder.append("(anonymous)"sv);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 CSS::Display Node::display() const
diff --git a/Userland/Libraries/LibWeb/Layout/Node.h b/Userland/Libraries/LibWeb/Layout/Node.h
index 1698f1352a3..e123355ea4c 100644
--- a/Userland/Libraries/LibWeb/Layout/Node.h
+++ b/Userland/Libraries/LibWeb/Layout/Node.h
@@ -85,7 +85,7 @@ public:
 
     bool is_root_element() const;
 
-    DeprecatedString debug_description() const;
+    ByteString debug_description() const;
 
     bool has_style() const { return m_has_style; }
     bool has_style_or_parent_with_style() const;
diff --git a/Userland/Libraries/LibWeb/Loader/ContentFilter.cpp b/Userland/Libraries/LibWeb/Loader/ContentFilter.cpp
index bf96499b5fa..5c229d44a5c 100644
--- a/Userland/Libraries/LibWeb/Loader/ContentFilter.cpp
+++ b/Userland/Libraries/LibWeb/Loader/ContentFilter.cpp
@@ -24,7 +24,7 @@ bool ContentFilter::is_filtered(const AK::URL& url) const
     if (url.scheme() == "data")
         return false;
 
-    auto url_string = url.to_deprecated_string();
+    auto url_string = url.to_byte_string();
 
     for (auto& pattern : m_patterns) {
         if (url_string.matches(pattern.text, CaseSensitivity::CaseSensitive))
diff --git a/Userland/Libraries/LibWeb/Loader/FileRequest.cpp b/Userland/Libraries/LibWeb/Loader/FileRequest.cpp
index f39e8f3ffd4..a9183b03d06 100644
--- a/Userland/Libraries/LibWeb/Loader/FileRequest.cpp
+++ b/Userland/Libraries/LibWeb/Loader/FileRequest.cpp
@@ -8,13 +8,13 @@
 
 namespace Web {
 
-FileRequest::FileRequest(DeprecatedString path, Function<void(ErrorOr<i32>)> on_file_request_finish_callback)
+FileRequest::FileRequest(ByteString path, Function<void(ErrorOr<i32>)> on_file_request_finish_callback)
     : on_file_request_finish(move(on_file_request_finish_callback))
     , m_path(move(path))
 {
 }
 
-DeprecatedString FileRequest::path() const
+ByteString FileRequest::path() const
 {
     return m_path;
 }
diff --git a/Userland/Libraries/LibWeb/Loader/FileRequest.h b/Userland/Libraries/LibWeb/Loader/FileRequest.h
index afa2b70eade..f898228ff77 100644
--- a/Userland/Libraries/LibWeb/Loader/FileRequest.h
+++ b/Userland/Libraries/LibWeb/Loader/FileRequest.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Function.h>
 
@@ -14,14 +14,14 @@ namespace Web {
 
 class FileRequest {
 public:
-    FileRequest(DeprecatedString path, Function<void(ErrorOr<i32>)> on_file_request_finish);
+    FileRequest(ByteString path, Function<void(ErrorOr<i32>)> on_file_request_finish);
 
-    DeprecatedString path() const;
+    ByteString path() const;
 
     Function<void(ErrorOr<i32>)> on_file_request_finish;
 
 private:
-    DeprecatedString m_path {};
+    ByteString m_path {};
 };
 
 }
diff --git a/Userland/Libraries/LibWeb/Loader/GeneratedPagesLoader.cpp b/Userland/Libraries/LibWeb/Loader/GeneratedPagesLoader.cpp
index 21d0a7b4eec..c293f8274d0 100644
--- a/Userland/Libraries/LibWeb/Loader/GeneratedPagesLoader.cpp
+++ b/Userland/Libraries/LibWeb/Loader/GeneratedPagesLoader.cpp
@@ -54,13 +54,13 @@ ErrorOr<String> load_error_page(AK::URL const& url)
 {
     // Generate HTML error page from error template file
     // FIXME: Use an actual templating engine (our own one when it's built, preferably with a way to check these usages at compile time)
-    auto template_path = AK::URL::create_with_url_or_path(error_page_url().to_deprecated_string()).serialize_path();
+    auto template_path = AK::URL::create_with_url_or_path(error_page_url().to_byte_string()).serialize_path();
     auto template_file = TRY(Core::File::open(template_path, Core::File::OpenMode::Read));
     auto template_contents = TRY(template_file->read_until_eof());
     StringBuilder builder;
     SourceGenerator generator { builder };
     generator.set("resource_directory_url", resource_directory_url());
-    generator.set("failed_url", url.to_deprecated_string());
+    generator.set("failed_url", url.to_byte_string());
     generator.append(template_contents);
     return TRY(String::from_utf8(generator.as_string_view()));
 }
@@ -70,7 +70,7 @@ ErrorOr<String> load_file_directory_page(LoadRequest const& request)
     // Generate HTML contents entries table
     auto lexical_path = LexicalPath(request.url().serialize_path());
     Core::DirIterator dt(lexical_path.string(), Core::DirIterator::Flags::SkipParentAndBaseDir);
-    Vector<DeprecatedString> names;
+    Vector<ByteString> names;
     while (dt.has_next())
         names.append(dt.next_path());
     quick_sort(names);
@@ -88,7 +88,7 @@ ErrorOr<String> load_file_directory_page(LoadRequest const& request)
             contents.appendff("<td><span class=\"{}\"></span></td>", is_directory ? "folder" : "file");
             contents.appendff("<td><a href=\"file://{}\">{}</a></td><td>&nbsp;</td>"sv, path, name);
             contents.appendff("<td>{:10}</td><td>&nbsp;</td>", is_directory ? "-" : human_readable_size(st.st_size));
-            contents.appendff("<td>{}</td>"sv, Core::DateTime::from_timestamp(st.st_mtime).to_deprecated_string());
+            contents.appendff("<td>{}</td>"sv, Core::DateTime::from_timestamp(st.st_mtime).to_byte_string());
             contents.append("</tr>\n"sv);
         }
     }
@@ -96,7 +96,7 @@ ErrorOr<String> load_file_directory_page(LoadRequest const& request)
 
     // Generate HTML directory page from directory template file
     // FIXME: Use an actual templating engine (our own one when it's built, preferably with a way to check these usages at compile time)
-    auto template_path = AK::URL::create_with_url_or_path(directory_page_url().to_deprecated_string()).serialize_path();
+    auto template_path = AK::URL::create_with_url_or_path(directory_page_url().to_byte_string()).serialize_path();
     auto template_file = TRY(Core::File::open(template_path, Core::File::OpenMode::Read));
     auto template_contents = TRY(template_file->read_until_eof());
     StringBuilder builder;
@@ -104,7 +104,7 @@ ErrorOr<String> load_file_directory_page(LoadRequest const& request)
     generator.set("resource_directory_url", resource_directory_url());
     generator.set("path", escape_html_entities(lexical_path.string()));
     generator.set("parent_path", escape_html_entities(lexical_path.parent().string()));
-    generator.set("contents", contents.to_deprecated_string());
+    generator.set("contents", contents.to_byte_string());
     generator.append(template_contents);
     return TRY(String::from_utf8(generator.as_string_view()));
 }
diff --git a/Userland/Libraries/LibWeb/Loader/LoadRequest.cpp b/Userland/Libraries/LibWeb/Loader/LoadRequest.cpp
index 5758408e56c..8ee1e192406 100644
--- a/Userland/Libraries/LibWeb/Loader/LoadRequest.cpp
+++ b/Userland/Libraries/LibWeb/Loader/LoadRequest.cpp
@@ -16,7 +16,7 @@ LoadRequest LoadRequest::create_for_url_on_page(const AK::URL& url, Page* page)
     request.set_url(url);
 
     if (page) {
-        DeprecatedString cookie = page->client().page_did_request_cookie(url, Cookie::Source::Http);
+        ByteString cookie = page->client().page_did_request_cookie(url, Cookie::Source::Http);
         if (!cookie.is_empty())
             request.set_header("Cookie", cookie);
         request.set_page(*page);
diff --git a/Userland/Libraries/LibWeb/Loader/LoadRequest.h b/Userland/Libraries/LibWeb/Loader/LoadRequest.h
index 39bf83cd828..8c90f008d3c 100644
--- a/Userland/Libraries/LibWeb/Loader/LoadRequest.h
+++ b/Userland/Libraries/LibWeb/Loader/LoadRequest.h
@@ -34,8 +34,8 @@ public:
     const AK::URL& url() const { return m_url; }
     void set_url(const AK::URL& url) { m_url = url; }
 
-    DeprecatedString const& method() const { return m_method; }
-    void set_method(DeprecatedString const& method) { m_method = method; }
+    ByteString const& method() const { return m_method; }
+    void set_method(ByteString const& method) { m_method = method; }
 
     ByteBuffer const& body() const { return m_body; }
     void set_body(ByteBuffer body) { m_body = move(body); }
@@ -50,7 +50,7 @@ public:
     {
         auto body_hash = string_hash((char const*)m_body.data(), m_body.size());
         auto body_and_headers_hash = pair_int_hash(body_hash, m_headers.hash());
-        auto url_and_method_hash = pair_int_hash(m_url.to_deprecated_string().hash(), m_method.hash());
+        auto url_and_method_hash = pair_int_hash(m_url.to_byte_string().hash(), m_method.hash());
         return pair_int_hash(body_and_headers_hash, url_and_method_hash);
     }
 
@@ -68,15 +68,15 @@ public:
         return m_url == other.m_url && m_method == other.m_method && m_body == other.m_body;
     }
 
-    void set_header(DeprecatedString const& name, DeprecatedString const& value) { m_headers.set(name, value); }
-    DeprecatedString header(DeprecatedString const& name) const { return m_headers.get(name).value_or({}); }
+    void set_header(ByteString const& name, ByteString const& value) { m_headers.set(name, value); }
+    ByteString header(ByteString const& name) const { return m_headers.get(name).value_or({}); }
 
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& headers() const { return m_headers; }
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& headers() const { return m_headers; }
 
 private:
     AK::URL m_url;
-    DeprecatedString m_method { "GET" };
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> m_headers;
+    ByteString m_method { "GET" };
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> m_headers;
     ByteBuffer m_body;
     Core::ElapsedTimer m_load_timer;
     JS::Handle<Page> m_page;
diff --git a/Userland/Libraries/LibWeb/Loader/ProxyMappings.cpp b/Userland/Libraries/LibWeb/Loader/ProxyMappings.cpp
index 687ea485fea..7edbd02b076 100644
--- a/Userland/Libraries/LibWeb/Loader/ProxyMappings.cpp
+++ b/Userland/Libraries/LibWeb/Loader/ProxyMappings.cpp
@@ -14,7 +14,7 @@ Web::ProxyMappings& Web::ProxyMappings::the()
 
 Core::ProxyData Web::ProxyMappings::proxy_for_url(AK::URL const& url) const
 {
-    auto url_string = url.to_deprecated_string();
+    auto url_string = url.to_byte_string();
     for (auto& it : m_mappings) {
         if (url_string.matches(it.key)) {
             auto result = Core::ProxyData::parse_url(m_proxies[it.value]);
@@ -29,7 +29,7 @@ Core::ProxyData Web::ProxyMappings::proxy_for_url(AK::URL const& url) const
     return {};
 }
 
-void Web::ProxyMappings::set_mappings(Vector<DeprecatedString> proxies, OrderedHashMap<DeprecatedString, size_t> mappings)
+void Web::ProxyMappings::set_mappings(Vector<ByteString> proxies, OrderedHashMap<ByteString, size_t> mappings)
 {
     m_proxies = move(proxies);
     m_mappings = move(mappings);
diff --git a/Userland/Libraries/LibWeb/Loader/ProxyMappings.h b/Userland/Libraries/LibWeb/Loader/ProxyMappings.h
index 900c54d470d..695e98f0208 100644
--- a/Userland/Libraries/LibWeb/Loader/ProxyMappings.h
+++ b/Userland/Libraries/LibWeb/Loader/ProxyMappings.h
@@ -18,14 +18,14 @@ public:
     static ProxyMappings& the();
 
     Core::ProxyData proxy_for_url(AK::URL const&) const;
-    void set_mappings(Vector<DeprecatedString> proxies, OrderedHashMap<DeprecatedString, size_t> mappings);
+    void set_mappings(Vector<ByteString> proxies, OrderedHashMap<ByteString, size_t> mappings);
 
 private:
     ProxyMappings() = default;
     ~ProxyMappings() = default;
 
-    Vector<DeprecatedString> m_proxies;
-    OrderedHashMap<DeprecatedString, size_t> m_mappings;
+    Vector<ByteString> m_proxies;
+    OrderedHashMap<ByteString, size_t> m_mappings;
 };
 
 }
diff --git a/Userland/Libraries/LibWeb/Loader/Resource.cpp b/Userland/Libraries/LibWeb/Loader/Resource.cpp
index cd741769f33..c4037cbdfe5 100644
--- a/Userland/Libraries/LibWeb/Loader/Resource.cpp
+++ b/Userland/Libraries/LibWeb/Loader/Resource.cpp
@@ -54,7 +54,7 @@ void Resource::for_each_client(Function<void(ResourceClient&)> callback)
     }
 }
 
-static Optional<DeprecatedString> encoding_from_content_type(DeprecatedString const& content_type)
+static Optional<ByteString> encoding_from_content_type(ByteString const& content_type)
 {
     auto offset = content_type.find("charset="sv);
     if (offset.has_value()) {
@@ -69,7 +69,7 @@ static Optional<DeprecatedString> encoding_from_content_type(DeprecatedString co
     return {};
 }
 
-static DeprecatedString mime_type_from_content_type(DeprecatedString const& content_type)
+static ByteString mime_type_from_content_type(ByteString const& content_type)
 {
     auto offset = content_type.find(';');
     if (offset.has_value())
@@ -83,7 +83,7 @@ static bool is_valid_encoding(StringView encoding)
     return TextCodec::decoder_for(encoding).has_value();
 }
 
-void Resource::did_load(Badge<ResourceLoader>, ReadonlyBytes data, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& headers, Optional<u32> status_code)
+void Resource::did_load(Badge<ResourceLoader>, ReadonlyBytes data, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& headers, Optional<u32> status_code)
 {
     VERIFY(m_state == State::Pending);
     // FIXME: Handle OOM failure.
@@ -125,7 +125,7 @@ void Resource::did_load(Badge<ResourceLoader>, ReadonlyBytes data, HashMap<Depre
     });
 }
 
-void Resource::did_fail(Badge<ResourceLoader>, DeprecatedString const& error, Optional<u32> status_code)
+void Resource::did_fail(Badge<ResourceLoader>, ByteString const& error, Optional<u32> status_code)
 {
     m_error = error;
     m_status_code = move(status_code);
diff --git a/Userland/Libraries/LibWeb/Loader/Resource.h b/Userland/Libraries/LibWeb/Loader/Resource.h
index 8531bbfff18..3c237002d57 100644
--- a/Userland/Libraries/LibWeb/Loader/Resource.h
+++ b/Userland/Libraries/LibWeb/Loader/Resource.h
@@ -46,14 +46,14 @@ public:
     bool is_loaded() const { return m_state == State::Loaded; }
     bool is_failed() const { return m_state == State::Failed; }
 
-    DeprecatedString const& error() const { return m_error; }
+    ByteString const& error() const { return m_error; }
 
     bool has_encoded_data() const { return !m_encoded_data.is_empty(); }
 
     const AK::URL& url() const { return m_request.url(); }
     ByteBuffer const& encoded_data() const { return m_encoded_data; }
 
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers() const { return m_response_headers; }
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers() const { return m_response_headers; }
 
     [[nodiscard]] Optional<u32> status_code() const { return m_status_code; }
 
@@ -61,13 +61,13 @@ public:
     void unregister_client(Badge<ResourceClient>, ResourceClient&);
 
     bool has_encoding() const { return m_encoding.has_value(); }
-    Optional<DeprecatedString> const& encoding() const { return m_encoding; }
-    DeprecatedString const& mime_type() const { return m_mime_type; }
+    Optional<ByteString> const& encoding() const { return m_encoding; }
+    ByteString const& mime_type() const { return m_mime_type; }
 
     void for_each_client(Function<void(ResourceClient&)>);
 
-    void did_load(Badge<ResourceLoader>, ReadonlyBytes data, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& headers, Optional<u32> status_code);
-    void did_fail(Badge<ResourceLoader>, DeprecatedString const& error, Optional<u32> status_code);
+    void did_load(Badge<ResourceLoader>, ReadonlyBytes data, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& headers, Optional<u32> status_code);
+    void did_fail(Badge<ResourceLoader>, ByteString const& error, Optional<u32> status_code);
 
 protected:
     explicit Resource(Type, LoadRequest const&);
@@ -80,11 +80,11 @@ private:
     ByteBuffer m_encoded_data;
     Type m_type { Type::Generic };
     State m_state { State::Pending };
-    DeprecatedString m_error;
-    Optional<DeprecatedString> m_encoding;
+    ByteString m_error;
+    Optional<ByteString> m_encoding;
 
-    DeprecatedString m_mime_type;
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> m_response_headers;
+    ByteString m_mime_type;
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> m_response_headers;
     Optional<u32> m_status_code;
     HashTable<ResourceClient*> m_clients;
 };
diff --git a/Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp b/Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp
index 9d580985b51..6bdbeb4da95 100644
--- a/Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp
+++ b/Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp
@@ -122,14 +122,14 @@ RefPtr<Resource> ResourceLoader::load_resource(Resource::Type type, LoadRequest&
     return resource;
 }
 
-static DeprecatedString sanitized_url_for_logging(AK::URL const& url)
+static ByteString sanitized_url_for_logging(AK::URL const& url)
 {
     if (url.scheme() == "data"sv)
         return "[data URL]"sv;
-    return url.to_deprecated_string();
+    return url.to_byte_string();
 }
 
-static void emit_signpost(DeprecatedString const& message, int id)
+static void emit_signpost(ByteString const& message, int id)
 {
 #ifdef AK_OS_SERENITY
     auto string_id = perf_register_string(message.characters(), message.length());
@@ -140,7 +140,7 @@ static void emit_signpost(DeprecatedString const& message, int id)
 #endif
 }
 
-static void store_response_cookies(Page& page, AK::URL const& url, DeprecatedString const& cookies)
+static void store_response_cookies(Page& page, AK::URL const& url, ByteString const& cookies)
 {
     auto set_cookie_json_value = MUST(JsonValue::from_string(cookies));
     VERIFY(set_cookie_json_value.type() == JsonValue::Type::Array);
@@ -165,23 +165,23 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
 
     auto id = resource_id++;
     auto url_for_logging = sanitized_url_for_logging(url);
-    emit_signpost(DeprecatedString::formatted("Starting load: {}", url_for_logging), id);
+    emit_signpost(ByteString::formatted("Starting load: {}", url_for_logging), id);
     dbgln_if(SPAM_DEBUG, "ResourceLoader: Starting load of: \"{}\"", url_for_logging);
 
     auto const log_success = [url_for_logging, id](auto const& request) {
         auto load_time_ms = request.load_time().to_milliseconds();
-        emit_signpost(DeprecatedString::formatted("Finished load: {}", url_for_logging), id);
+        emit_signpost(ByteString::formatted("Finished load: {}", url_for_logging), id);
         dbgln_if(SPAM_DEBUG, "ResourceLoader: Finished load of: \"{}\", Duration: {}ms", url_for_logging, load_time_ms);
     };
 
     auto const log_failure = [url_for_logging, id](auto const& request, auto const& error_message) {
         auto load_time_ms = request.load_time().to_milliseconds();
-        emit_signpost(DeprecatedString::formatted("Failed load: {}", url_for_logging), id);
+        emit_signpost(ByteString::formatted("Failed load: {}", url_for_logging), id);
         dbgln("ResourceLoader: Failed load of: \"{}\", \033[31;1mError: {}\033[0m, Duration: {}ms", url_for_logging, error_message, load_time_ms);
     };
 
     if (is_port_blocked(url.port_or_default())) {
-        log_failure(request, DeprecatedString::formatted("The port #{} is blocked", url.port_or_default()));
+        log_failure(request, ByteString::formatted("The port #{} is blocked", url.port_or_default()));
         return;
     }
 
@@ -196,11 +196,11 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
         dbgln_if(SPAM_DEBUG, "Loading about: URL {}", url);
         log_success(request);
 
-        HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> response_headers;
+        HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> response_headers;
         response_headers.set("Content-Type", "text/html; charset=UTF-8");
 
         Platform::EventLoopPlugin::the().deferred_invoke([success_callback = move(success_callback), response_headers = move(response_headers)] {
-            success_callback(DeprecatedString::empty().to_byte_buffer(), response_headers, {});
+            success_callback(ByteString::empty().to_byte_buffer(), response_headers, {});
         });
         return;
     }
@@ -219,8 +219,8 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
             data_url.mime_type,
             StringView(data_url.body.bytes()));
 
-        HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> response_headers;
-        response_headers.set("Content-Type", data_url.mime_type.to_deprecated_string());
+        HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> response_headers;
+        response_headers.set("Content-Type", data_url.mime_type.to_byte_string());
 
         log_success(request);
 
@@ -248,7 +248,7 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
                 log_failure(request, file_or_error.error());
                 if (error_callback) {
                     auto status = file_or_error.error().code() == ENOENT ? 404u : 500u;
-                    error_callback(DeprecatedString::formatted("{}", file_or_error.error()), status, {}, {});
+                    error_callback(ByteString::formatted("{}", file_or_error.error()), status, {}, {});
                 }
                 return;
             }
@@ -262,12 +262,12 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
                 if (maybe_response.is_error()) {
                     log_failure(request, maybe_response.error());
                     if (error_callback)
-                        error_callback(DeprecatedString::formatted("{}", maybe_response.error()), 500u, {}, {});
+                        error_callback(ByteString::formatted("{}", maybe_response.error()), 500u, {}, {});
                     return;
                 }
 
                 log_success(request);
-                HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> response_headers;
+                HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> response_headers;
                 response_headers.set("Content-Type"sv, "text/html"sv);
                 success_callback(maybe_response.release_value().bytes(), response_headers, {});
                 return;
@@ -278,7 +278,7 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
             if (maybe_file.is_error()) {
                 log_failure(request, maybe_file.error());
                 if (error_callback)
-                    error_callback(DeprecatedString::formatted("{}", maybe_file.error()), 500u, {}, {});
+                    error_callback(ByteString::formatted("{}", maybe_file.error()), 500u, {}, {});
                 return;
             }
 
@@ -287,7 +287,7 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
             if (maybe_data.is_error()) {
                 log_failure(request, maybe_data.error());
                 if (error_callback)
-                    error_callback(DeprecatedString::formatted("{}", maybe_data.error()), 500u, {}, {});
+                    error_callback(ByteString::formatted("{}", maybe_data.error()), 500u, {}, {});
                 return;
             }
             auto data = maybe_data.release_value();
@@ -295,7 +295,7 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
 
             // NOTE: For file:// URLs, we have to guess the MIME type, since there's no HTTP header to tell us what this is.
             //       We insert a fake Content-Type header here, so that clients can use it to learn the MIME type.
-            HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> response_headers;
+            HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> response_headers;
             auto mime_type = Core::guess_mime_type_based_on_filename(request.url().serialize_path());
             response_headers.set("Content-Type"sv, mime_type);
 
@@ -314,8 +314,8 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
     if (url.scheme() == "http" || url.scheme() == "https" || url.scheme() == "gemini") {
         auto proxy = ProxyMappings::the().proxy_for_url(url);
 
-        HashMap<DeprecatedString, DeprecatedString> headers;
-        headers.set("User-Agent", m_user_agent.to_deprecated_string());
+        HashMap<ByteString, ByteString> headers;
+        headers.set("User-Agent", m_user_agent.to_byte_string());
         headers.set("Accept-Encoding", "gzip, deflate, br");
 
         for (auto& it : request.headers()) {
@@ -366,7 +366,7 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
                     error_builder.append("Load failed"sv);
                 log_failure(request, error_builder.string_view());
                 if (error_callback)
-                    error_callback(error_builder.to_deprecated_string(), status_code, payload, response_headers);
+                    error_callback(error_builder.to_byte_string(), status_code, payload, response_headers);
                 return;
             }
             log_success(request);
@@ -385,7 +385,7 @@ void ResourceLoader::load(LoadRequest& request, SuccessCallback success_callback
         return;
     }
 
-    auto not_implemented_error = DeprecatedString::formatted("Protocol not implemented: {}", url.scheme());
+    auto not_implemented_error = ByteString::formatted("Protocol not implemented: {}", url.scheme());
     log_failure(request, not_implemented_error);
     if (error_callback)
         error_callback(not_implemented_error, {}, {}, {});
diff --git a/Userland/Libraries/LibWeb/Loader/ResourceLoader.h b/Userland/Libraries/LibWeb/Loader/ResourceLoader.h
index a75e535e6c8..fc107383f88 100644
--- a/Userland/Libraries/LibWeb/Loader/ResourceLoader.h
+++ b/Userland/Libraries/LibWeb/Loader/ResourceLoader.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/URL.h>
@@ -69,8 +69,8 @@ public:
     virtual ~ResourceLoaderConnectorRequest();
 
     struct CertificateAndKey {
-        DeprecatedString certificate;
-        DeprecatedString key;
+        ByteString certificate;
+        ByteString key;
     };
 
     virtual void set_should_buffer_all_input(bool) = 0;
@@ -78,7 +78,7 @@ public:
 
     virtual void stream_into(Stream&) = 0;
 
-    Function<void(bool success, u64 total_size, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code, ReadonlyBytes payload)> on_buffered_request_finish;
+    Function<void(bool success, u64 total_size, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> response_code, ReadonlyBytes payload)> on_buffered_request_finish;
     Function<void(bool success, u64 total_size)> on_finish;
     Function<void(Optional<u64> total_size, u64 downloaded_size)> on_progress;
     Function<CertificateAndKey()> on_certificate_requested;
@@ -94,7 +94,7 @@ public:
     virtual void prefetch_dns(AK::URL const&) = 0;
     virtual void preconnect(AK::URL const&) = 0;
 
-    virtual RefPtr<ResourceLoaderConnectorRequest> start_request(DeprecatedString const& method, AK::URL const&, HashMap<DeprecatedString, DeprecatedString> const& request_headers = {}, ReadonlyBytes request_body = {}, Core::ProxyData const& = {}) = 0;
+    virtual RefPtr<ResourceLoaderConnectorRequest> start_request(ByteString const& method, AK::URL const&, HashMap<ByteString, ByteString> const& request_headers = {}, ReadonlyBytes request_body = {}, Core::ProxyData const& = {}) = 0;
 
 protected:
     explicit ResourceLoaderConnector();
@@ -108,8 +108,8 @@ public:
 
     RefPtr<Resource> load_resource(Resource::Type, LoadRequest&);
 
-    using SuccessCallback = Function<void(ReadonlyBytes, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> status_code)>;
-    using ErrorCallback = Function<void(DeprecatedString const&, Optional<u32> status_code, ReadonlyBytes payload, HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers)>;
+    using SuccessCallback = Function<void(ReadonlyBytes, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers, Optional<u32> status_code)>;
+    using ErrorCallback = Function<void(ByteString const&, Optional<u32> status_code, ReadonlyBytes payload, HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers)>;
     using TimeoutCallback = Function<void()>;
 
     void load(LoadRequest&, SuccessCallback success_callback, ErrorCallback error_callback = nullptr, Optional<u32> timeout = {}, TimeoutCallback timeout_callback = nullptr);
diff --git a/Userland/Libraries/LibWeb/Page/EventHandler.cpp b/Userland/Libraries/LibWeb/Page/EventHandler.cpp
index 5398f00b004..77ecfad460d 100644
--- a/Userland/Libraries/LibWeb/Page/EventHandler.cpp
+++ b/Userland/Libraries/LibWeb/Page/EventHandler.cpp
@@ -533,7 +533,7 @@ bool EventHandler::handle_mousemove(CSSPixelPoint position, CSSPixelPoint screen
     if (hovered_node_changed) {
         JS::GCPtr<HTML::HTMLElement const> hovered_html_element = document.hovered_node() ? document.hovered_node()->enclosing_html_element_with_attribute(HTML::AttributeNames::title) : nullptr;
         if (hovered_html_element && hovered_html_element->title().has_value()) {
-            page.client().page_did_enter_tooltip_area(m_browsing_context->to_top_level_position(position), hovered_html_element->title()->to_deprecated_string());
+            page.client().page_did_enter_tooltip_area(m_browsing_context->to_top_level_position(position), hovered_html_element->title()->to_byte_string());
         } else {
             page.client().page_did_leave_tooltip_area();
         }
diff --git a/Userland/Libraries/LibWeb/Page/Page.cpp b/Userland/Libraries/LibWeb/Page/Page.cpp
index 6ada7e7a5ff..728b0507e60 100644
--- a/Userland/Libraries/LibWeb/Page/Page.cpp
+++ b/Userland/Libraries/LibWeb/Page/Page.cpp
@@ -353,7 +353,7 @@ void Page::select_dropdown_closed(Optional<String> value)
     }
 }
 
-void Page::did_request_media_context_menu(i32 media_id, CSSPixelPoint position, DeprecatedString const& target, unsigned modifiers, MediaContextMenu menu)
+void Page::did_request_media_context_menu(i32 media_id, CSSPixelPoint position, ByteString const& target, unsigned modifiers, MediaContextMenu menu)
 {
     m_media_context_menu_element_id = media_id;
     client().page_did_request_media_context_menu(position, target, modifiers, move(menu));
diff --git a/Userland/Libraries/LibWeb/Page/Page.h b/Userland/Libraries/LibWeb/Page/Page.h
index ae9d466bf90..7fd2d11737b 100644
--- a/Userland/Libraries/LibWeb/Page/Page.h
+++ b/Userland/Libraries/LibWeb/Page/Page.h
@@ -146,7 +146,7 @@ public:
         bool has_user_agent_controls { false };
         bool is_looping { false };
     };
-    void did_request_media_context_menu(i32 media_id, CSSPixelPoint, DeprecatedString const& target, unsigned modifiers, MediaContextMenu);
+    void did_request_media_context_menu(i32 media_id, CSSPixelPoint, ByteString const& target, unsigned modifiers, MediaContextMenu);
     WebIDL::ExceptionOr<void> toggle_media_play_state();
     void toggle_media_mute_state();
     WebIDL::ExceptionOr<void> toggle_media_loop_state();
@@ -224,7 +224,7 @@ public:
     virtual double device_pixels_per_css_pixel() const = 0;
     virtual CSS::PreferredColorScheme preferred_color_scheme() const = 0;
     virtual void paint(DevicePixelRect const&, Gfx::Bitmap&, PaintOptions = {}) = 0;
-    virtual void page_did_change_title(DeprecatedString const&) { }
+    virtual void page_did_change_title(ByteString const&) { }
     virtual void page_did_request_navigate_back() { }
     virtual void page_did_request_navigate_forward() { }
     virtual void page_did_request_refresh() { }
@@ -241,12 +241,12 @@ public:
     virtual void page_did_change_selection() { }
     virtual void page_did_request_cursor_change(Gfx::StandardCursor) { }
     virtual void page_did_request_context_menu(CSSPixelPoint) { }
-    virtual void page_did_request_link_context_menu(CSSPixelPoint, AK::URL const&, [[maybe_unused]] DeprecatedString const& target, [[maybe_unused]] unsigned modifiers) { }
-    virtual void page_did_request_image_context_menu(CSSPixelPoint, AK::URL const&, [[maybe_unused]] DeprecatedString const& target, [[maybe_unused]] unsigned modifiers, Gfx::Bitmap const*) { }
-    virtual void page_did_request_media_context_menu(CSSPixelPoint, [[maybe_unused]] DeprecatedString const& target, [[maybe_unused]] unsigned modifiers, Page::MediaContextMenu) { }
-    virtual void page_did_click_link(const AK::URL&, [[maybe_unused]] DeprecatedString const& target, [[maybe_unused]] unsigned modifiers) { }
-    virtual void page_did_middle_click_link(const AK::URL&, [[maybe_unused]] DeprecatedString const& target, [[maybe_unused]] unsigned modifiers) { }
-    virtual void page_did_enter_tooltip_area(CSSPixelPoint, DeprecatedString const&) { }
+    virtual void page_did_request_link_context_menu(CSSPixelPoint, AK::URL const&, [[maybe_unused]] ByteString const& target, [[maybe_unused]] unsigned modifiers) { }
+    virtual void page_did_request_image_context_menu(CSSPixelPoint, AK::URL const&, [[maybe_unused]] ByteString const& target, [[maybe_unused]] unsigned modifiers, Gfx::Bitmap const*) { }
+    virtual void page_did_request_media_context_menu(CSSPixelPoint, [[maybe_unused]] ByteString const& target, [[maybe_unused]] unsigned modifiers, Page::MediaContextMenu) { }
+    virtual void page_did_click_link(const AK::URL&, [[maybe_unused]] ByteString const& target, [[maybe_unused]] unsigned modifiers) { }
+    virtual void page_did_middle_click_link(const AK::URL&, [[maybe_unused]] ByteString const& target, [[maybe_unused]] unsigned modifiers) { }
+    virtual void page_did_enter_tooltip_area(CSSPixelPoint, ByteString const&) { }
     virtual void page_did_leave_tooltip_area() { }
     virtual void page_did_hover_link(const AK::URL&) { }
     virtual void page_did_unhover_link() { }
@@ -263,8 +263,8 @@ public:
     virtual void page_did_request_accept_dialog() { }
     virtual void page_did_request_dismiss_dialog() { }
     virtual Vector<Web::Cookie::Cookie> page_did_request_all_cookies(AK::URL const&) { return {}; }
-    virtual Optional<Web::Cookie::Cookie> page_did_request_named_cookie(AK::URL const&, DeprecatedString const&) { return {}; }
-    virtual DeprecatedString page_did_request_cookie(const AK::URL&, Cookie::Source) { return {}; }
+    virtual Optional<Web::Cookie::Cookie> page_did_request_named_cookie(AK::URL const&, ByteString const&) { return {}; }
+    virtual ByteString page_did_request_cookie(const AK::URL&, Cookie::Source) { return {}; }
     virtual void page_did_set_cookie(const AK::URL&, Cookie::ParsedCookie const&, Cookie::Source) { }
     virtual void page_did_update_cookie(Web::Cookie::Cookie) { }
     virtual void page_did_update_resource_count(i32) { }
diff --git a/Userland/Libraries/LibWeb/Painting/MediaPaintable.cpp b/Userland/Libraries/LibWeb/Painting/MediaPaintable.cpp
index d7836e03061..52f9e106c8e 100644
--- a/Userland/Libraries/LibWeb/Painting/MediaPaintable.cpp
+++ b/Userland/Libraries/LibWeb/Painting/MediaPaintable.cpp
@@ -351,7 +351,7 @@ MediaPaintable::DispatchEventOfSameName MediaPaintable::handle_mousemove(Badge<E
                 set_volume(media_element, *cached_layout_boxes.volume_scrub_rect, position);
 
                 auto volume = static_cast<u8>(media_element.volume() * 100.0);
-                browsing_context().page().client().page_did_enter_tooltip_area(position, DeprecatedString::formatted("{}%", volume));
+                browsing_context().page().client().page_did_enter_tooltip_area(position, ByteString::formatted("{}%", volume));
             }
 
             break;
diff --git a/Userland/Libraries/LibWeb/Painting/PaintableBox.cpp b/Userland/Libraries/LibWeb/Painting/PaintableBox.cpp
index 21d75ce806a..48dd128da3e 100644
--- a/Userland/Libraries/LibWeb/Painting/PaintableBox.cpp
+++ b/Userland/Libraries/LibWeb/Painting/PaintableBox.cpp
@@ -282,7 +282,7 @@ void PaintableBox::paint(PaintContext& context, PaintPhase phase) const
         else
             builder.append(layout_box().debug_description());
         builder.appendff(" {}x{} @ {},{}", border_rect.width(), border_rect.height(), border_rect.x(), border_rect.y());
-        auto size_text = builder.to_deprecated_string();
+        auto size_text = builder.to_byte_string();
         auto size_text_rect = border_rect;
         size_text_rect.set_y(border_rect.y() + border_rect.height());
         size_text_rect.set_top(size_text_rect.top());
diff --git a/Userland/Libraries/LibWeb/Platform/FontPluginSerenity.cpp b/Userland/Libraries/LibWeb/Platform/FontPluginSerenity.cpp
index c9faa15001a..45359c28951 100644
--- a/Userland/Libraries/LibWeb/Platform/FontPluginSerenity.cpp
+++ b/Userland/Libraries/LibWeb/Platform/FontPluginSerenity.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "FontPluginSerenity.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibGfx/Font/FontDatabase.h>
 
 namespace Web::Platform {
diff --git a/Userland/Libraries/LibWeb/SVG/SVGScriptElement.cpp b/Userland/Libraries/LibWeb/SVG/SVGScriptElement.cpp
index 3fa1d6aac50..540b1f01c1f 100644
--- a/Userland/Libraries/LibWeb/SVG/SVGScriptElement.cpp
+++ b/Userland/Libraries/LibWeb/SVG/SVGScriptElement.cpp
@@ -59,7 +59,7 @@ void SVGScriptElement::process_the_script_element()
     auto& settings_object = document().relevant_settings_object();
     auto base_url = document().base_url();
 
-    m_script = HTML::ClassicScript::create(m_document->url().to_deprecated_string(), inline_script, settings_object, base_url, m_source_line_number);
+    m_script = HTML::ClassicScript::create(m_document->url().to_byte_string(), inline_script, settings_object, base_url, m_source_line_number);
     (void)m_script->run();
 }
 
diff --git a/Userland/Libraries/LibWeb/SVG/SVGTextContentElement.cpp b/Userland/Libraries/LibWeb/SVG/SVGTextContentElement.cpp
index 060d6c917f2..38d374c8927 100644
--- a/Userland/Libraries/LibWeb/SVG/SVGTextContentElement.cpp
+++ b/Userland/Libraries/LibWeb/SVG/SVGTextContentElement.cpp
@@ -45,9 +45,9 @@ Optional<TextAnchor> SVGTextContentElement::text_anchor() const
     }
 }
 
-DeprecatedString SVGTextContentElement::text_contents() const
+ByteString SVGTextContentElement::text_contents() const
 {
-    return child_text_content().to_deprecated_string().trim_whitespace();
+    return child_text_content().to_byte_string().trim_whitespace();
 }
 
 // https://svgwg.org/svg2-draft/text.html#__svg__SVGTextContentElement__getNumberOfChars
diff --git a/Userland/Libraries/LibWeb/SVG/SVGTextContentElement.h b/Userland/Libraries/LibWeb/SVG/SVGTextContentElement.h
index c1a467c48b9..10ea63a8cb3 100644
--- a/Userland/Libraries/LibWeb/SVG/SVGTextContentElement.h
+++ b/Userland/Libraries/LibWeb/SVG/SVGTextContentElement.h
@@ -21,7 +21,7 @@ public:
 
     Optional<TextAnchor> text_anchor() const;
 
-    DeprecatedString text_contents() const;
+    ByteString text_contents() const;
 
 protected:
     SVGTextContentElement(DOM::Document&, DOM::QualifiedName);
diff --git a/Userland/Libraries/LibWeb/SVG/SVGTitleElement.cpp b/Userland/Libraries/LibWeb/SVG/SVGTitleElement.cpp
index efb93c979f9..0c1783d7eaf 100644
--- a/Userland/Libraries/LibWeb/SVG/SVGTitleElement.cpp
+++ b/Userland/Libraries/LibWeb/SVG/SVGTitleElement.cpp
@@ -40,7 +40,7 @@ void SVGTitleElement::children_changed()
     auto* document_element = document().document_element();
 
     if (document_element == parent() && is<SVGElement>(document_element))
-        page.client().page_did_change_title(document().title().to_deprecated_string());
+        page.client().page_did_change_title(document().title().to_byte_string());
 }
 
 }
diff --git a/Userland/Libraries/LibWeb/SVG/SVGUseElement.cpp b/Userland/Libraries/LibWeb/SVG/SVGUseElement.cpp
index c829bf480d1..ca8acab023b 100644
--- a/Userland/Libraries/LibWeb/SVG/SVGUseElement.cpp
+++ b/Userland/Libraries/LibWeb/SVG/SVGUseElement.cpp
@@ -58,13 +58,13 @@ void SVGUseElement::attribute_changed(FlyString const& name, Optional<String> co
         m_y = AttributeParser::parse_coordinate(value.value_or(String {}));
     } else if (name == SVG::AttributeNames::href) {
         // FIXME: Support the xlink:href attribute as a fallback
-        m_referenced_id = parse_id_from_href(value.value_or(String {}).to_deprecated_string());
+        m_referenced_id = parse_id_from_href(value.value_or(String {}).to_byte_string());
 
         clone_element_tree_as_our_shadow_tree(referenced_element());
     }
 }
 
-Optional<FlyString> SVGUseElement::parse_id_from_href(DeprecatedString const& href)
+Optional<FlyString> SVGUseElement::parse_id_from_href(ByteString const& href)
 {
     auto id_seperator = href.find('#');
     if (!id_seperator.has_value()) {
diff --git a/Userland/Libraries/LibWeb/SVG/SVGUseElement.h b/Userland/Libraries/LibWeb/SVG/SVGUseElement.h
index 0e59e258530..c768444b56d 100644
--- a/Userland/Libraries/LibWeb/SVG/SVGUseElement.h
+++ b/Userland/Libraries/LibWeb/SVG/SVGUseElement.h
@@ -48,7 +48,7 @@ private:
 
     virtual JS::GCPtr<Layout::Node> create_layout_node(NonnullRefPtr<CSS::StyleProperties>) override;
 
-    Optional<FlyString> parse_id_from_href(DeprecatedString const& href);
+    Optional<FlyString> parse_id_from_href(ByteString const& href);
 
     JS::GCPtr<DOM::Element> referenced_element();
 
diff --git a/Userland/Libraries/LibWeb/Streams/UnderlyingSource.cpp b/Userland/Libraries/LibWeb/Streams/UnderlyingSource.cpp
index 45e68750ea9..ec6846f4ca0 100644
--- a/Userland/Libraries/LibWeb/Streams/UnderlyingSource.cpp
+++ b/Userland/Libraries/LibWeb/Streams/UnderlyingSource.cpp
@@ -32,7 +32,7 @@ JS::ThrowCompletionOr<UnderlyingSource> UnderlyingSource::from_value(JS::VM& vm,
         if (type_string == "bytes"sv)
             underlying_source.type = ReadableStreamType::Bytes;
         else
-            return vm.throw_completion<JS::TypeError>(DeprecatedString::formatted("Unknown stream type '{}'", type_value));
+            return vm.throw_completion<JS::TypeError>(ByteString::formatted("Unknown stream type '{}'", type_value));
     }
 
     if (TRY(object.has_property("autoAllocateChunkSize")))
diff --git a/Userland/Libraries/LibWeb/URL/URL.cpp b/Userland/Libraries/LibWeb/URL/URL.cpp
index 951bca40238..02545a6806b 100644
--- a/Userland/Libraries/LibWeb/URL/URL.cpp
+++ b/Userland/Libraries/LibWeb/URL/URL.cpp
@@ -148,7 +148,7 @@ WebIDL::ExceptionOr<String> URL::href() const
     auto& vm = realm().vm();
 
     // The href getter steps and the toJSON() method steps are to return the serialization of this’s URL.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_url.serialize()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(m_url.serialize()));
 }
 
 // https://url.spec.whatwg.org/#dom-url-tojson
@@ -157,7 +157,7 @@ WebIDL::ExceptionOr<String> URL::to_json() const
     auto& vm = realm().vm();
 
     // The href getter steps and the toJSON() method steps are to return the serialization of this’s URL.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_url.serialize()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(m_url.serialize()));
 }
 
 // https://url.spec.whatwg.org/#ref-for-dom-url-href②
@@ -193,7 +193,7 @@ WebIDL::ExceptionOr<String> URL::origin() const
     auto& vm = realm().vm();
 
     // The origin getter steps are to return the serialization of this’s URL’s origin. [HTML]
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_url.serialize_origin()));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(m_url.serialize_origin()));
 }
 
 // https://url.spec.whatwg.org/#dom-url-protocol
@@ -355,7 +355,7 @@ WebIDL::ExceptionOr<String> URL::pathname() const
     auto& vm = realm().vm();
 
     // The pathname getter steps are to return the result of URL path serializing this’s URL.
-    return TRY_OR_THROW_OOM(vm, String::from_deprecated_string(m_url.serialize_path(AK::URL::ApplyPercentDecoding::No)));
+    return TRY_OR_THROW_OOM(vm, String::from_byte_string(m_url.serialize_path(AK::URL::ApplyPercentDecoding::No)));
 }
 
 // https://url.spec.whatwg.org/#ref-for-dom-url-pathname%E2%91%A0
@@ -517,14 +517,14 @@ HTML::Origin url_origin(AK::URL const& url)
     // -> "wss"
     if (url.scheme().is_one_of("ftp"sv, "http"sv, "https"sv, "ws"sv, "wss"sv)) {
         // Return the tuple origin (url’s scheme, url’s host, url’s port, null).
-        return HTML::Origin(url.scheme().to_deprecated_string(), url.host(), url.port().value_or(0));
+        return HTML::Origin(url.scheme().to_byte_string(), url.host(), url.port().value_or(0));
     }
 
     // -> "file"
     if (url.scheme() == "file"sv) {
         // Unfortunate as it is, this is left as an exercise to the reader. When in doubt, return a new opaque origin.
         // Note: We must return an origin with the `file://' protocol for `file://' iframes to work from `file://' pages.
-        return HTML::Origin(url.scheme().to_deprecated_string(), String {}, 0);
+        return HTML::Origin(url.scheme().to_byte_string(), String {}, 0);
     }
 
     // -> Otherwise
diff --git a/Userland/Libraries/LibWeb/URL/URL.h b/Userland/Libraries/LibWeb/URL/URL.h
index f8a70748d14..1ea75596167 100644
--- a/Userland/Libraries/LibWeb/URL/URL.h
+++ b/Userland/Libraries/LibWeb/URL/URL.h
@@ -58,9 +58,9 @@ public:
 
     Optional<String> const& fragment() const { return m_url.fragment(); }
 
-    DeprecatedString path_segment_at_index(size_t index) const { return m_url.path_segment_at_index(index); }
+    ByteString path_segment_at_index(size_t index) const { return m_url.path_segment_at_index(index); }
 
-    void set_paths(Vector<DeprecatedString> const& paths) { return m_url.set_paths(paths); }
+    void set_paths(Vector<ByteString> const& paths) { return m_url.set_paths(paths); }
 
     // FIXME: Reimplement this to meet the definition in https://url.spec.whatwg.org/#url-opaque-path once we modernize URL to meet the spec.
     bool cannot_be_a_base_url() const { return m_url.cannot_be_a_base_url(); }
diff --git a/Userland/Libraries/LibWeb/URL/URLSearchParams.cpp b/Userland/Libraries/LibWeb/URL/URLSearchParams.cpp
index 00605a93b63..475ef03d1e9 100644
--- a/Userland/Libraries/LibWeb/URL/URLSearchParams.cpp
+++ b/Userland/Libraries/LibWeb/URL/URLSearchParams.cpp
@@ -109,8 +109,8 @@ ErrorOr<Vector<QueryParam>> url_decode(StringView input)
         auto space_decoded_name = name.replace("+"sv, " "sv, ReplaceMode::All);
 
         // 5. Let nameString and valueString be the result of running UTF-8 decode without BOM on the percent-decoding of name and value, respectively.
-        auto name_string = TRY(String::from_deprecated_string(AK::URL::percent_decode(space_decoded_name)));
-        auto value_string = TRY(String::from_deprecated_string(AK::URL::percent_decode(value)));
+        auto name_string = TRY(String::from_byte_string(AK::URL::percent_decode(space_decoded_name)));
+        auto value_string = TRY(String::from_byte_string(AK::URL::percent_decode(value)));
 
         TRY(output.try_empend(move(name_string), move(value_string)));
     }
diff --git a/Userland/Libraries/LibWeb/WebAssembly/WebAssembly.cpp b/Userland/Libraries/LibWeb/WebAssembly/WebAssembly.cpp
index 7f1600832e5..11fe74d4c21 100644
--- a/Userland/Libraries/LibWeb/WebAssembly/WebAssembly.cpp
+++ b/Userland/Libraries/LibWeb/WebAssembly/WebAssembly.cpp
@@ -207,7 +207,7 @@ JS::ThrowCompletionOr<size_t> instantiate_module(JS::VM& vm, Wasm::Module const&
                             auto values = TRY(JS::iterator_to_list(vm, TRY(JS::get_iterator_from_method(vm, result, *method))));
 
                             if (values.size() != type.results().size())
-                                return vm.throw_completion<JS::TypeError>(DeprecatedString::formatted("Invalid number of return values for multi-value wasm return of {} objects", type.results().size()));
+                                return vm.throw_completion<JS::TypeError>(ByteString::formatted("Invalid number of return values for multi-value wasm return of {} objects", type.results().size()));
 
                             Vector<Wasm::Value> wasm_values;
                             TRY_OR_THROW_OOM(vm, wasm_values.try_ensure_capacity(values.size()));
@@ -320,7 +320,7 @@ JS::ThrowCompletionOr<size_t> parse_module(JS::VM& vm, JS::Object* buffer_object
     auto module_result = Wasm::Module::parse(stream);
     if (module_result.is_error()) {
         // FIXME: Throw CompileError instead.
-        return vm.throw_completion<JS::TypeError>(Wasm::parse_error_to_deprecated_string(module_result.error()));
+        return vm.throw_completion<JS::TypeError>(Wasm::parse_error_to_byte_string(module_result.error()));
     }
 
     if (auto validation_result = s_abstract_machine.validate(module_result.value()); validation_result.is_error()) {
@@ -332,7 +332,7 @@ JS::ThrowCompletionOr<size_t> parse_module(JS::VM& vm, JS::Object* buffer_object
     return s_compiled_modules.size() - 1;
 }
 
-JS::NativeFunction* create_native_function(JS::VM& vm, Wasm::FunctionAddress address, DeprecatedString const& name)
+JS::NativeFunction* create_native_function(JS::VM& vm, Wasm::FunctionAddress address, ByteString const& name)
 {
     auto& realm = *vm.current_realm();
     Optional<Wasm::FunctionType> type;
diff --git a/Userland/Libraries/LibWeb/WebAssembly/WebAssembly.h b/Userland/Libraries/LibWeb/WebAssembly/WebAssembly.h
index 6719b440288..543a963f9f4 100644
--- a/Userland/Libraries/LibWeb/WebAssembly/WebAssembly.h
+++ b/Userland/Libraries/LibWeb/WebAssembly/WebAssembly.h
@@ -30,7 +30,7 @@ namespace Detail {
 
 JS::ThrowCompletionOr<size_t> instantiate_module(JS::VM&, Wasm::Module const&);
 JS::ThrowCompletionOr<size_t> parse_module(JS::VM&, JS::Object* buffer);
-JS::NativeFunction* create_native_function(JS::VM&, Wasm::FunctionAddress address, DeprecatedString const& name);
+JS::NativeFunction* create_native_function(JS::VM&, Wasm::FunctionAddress address, ByteString const& name);
 JS::ThrowCompletionOr<Wasm::Value> to_webassembly_value(JS::VM&, JS::Value value, Wasm::ValueType const& type);
 JS::Value to_js_value(JS::VM&, Wasm::Value& wasm_value);
 
diff --git a/Userland/Libraries/LibWeb/WebDriver/Capabilities.cpp b/Userland/Libraries/LibWeb/WebDriver/Capabilities.cpp
index 415fcb227da..83405eed825 100644
--- a/Userland/Libraries/LibWeb/WebDriver/Capabilities.cpp
+++ b/Userland/Libraries/LibWeb/WebDriver/Capabilities.cpp
@@ -103,7 +103,7 @@ static ErrorOr<JsonObject, Error> validate_capabilities(JsonValue const& capabil
         else if (name.is_one_of("browserName"sv, "browserVersion"sv, "platformName"sv)) {
             // If value is not a string return an error with error code invalid argument. Otherwise, let deserialized be set to value.
             if (!value.is_string())
-                return Error::from_code(ErrorCode::InvalidArgument, DeprecatedString::formatted("Capability {} must be a string", name));
+                return Error::from_code(ErrorCode::InvalidArgument, ByteString::formatted("Capability {} must be a string", name));
             deserialized = value;
         }
 
@@ -149,7 +149,7 @@ static ErrorOr<JsonObject, Error> validate_capabilities(JsonValue const& capabil
         // -> The remote end is an endpoint node
         else {
             // Return an error with error code invalid argument.
-            return Error::from_code(ErrorCode::InvalidArgument, DeprecatedString::formatted("Unrecognized capability: {}", name));
+            return Error::from_code(ErrorCode::InvalidArgument, ByteString::formatted("Unrecognized capability: {}", name));
         }
 
         // d. If deserialized is not null, set a property on result with name name and value deserialized.
@@ -192,7 +192,7 @@ static ErrorOr<JsonObject, Error> merge_capabilities(JsonObject const& primary,
 
         // d. If primary value is not undefined, return an error with error code invalid argument.
         if (primary_value.has_value())
-            return Error::from_code(ErrorCode::InvalidArgument, DeprecatedString::formatted("Unable to merge capability {}", name));
+            return Error::from_code(ErrorCode::InvalidArgument, ByteString::formatted("Unable to merge capability {}", name));
 
         // e. Set a property on result with name name and value value.
         result.set(name, value);
@@ -267,20 +267,20 @@ static JsonValue match_capabilities(JsonObject const& capabilities)
         // -> "browserName"
         if (name == "browserName"sv) {
             // If value is not a string equal to the "browserName" entry in matched capabilities, return success with data null.
-            if (value.as_string() != matched_capabilities.get_deprecated_string(name).value())
+            if (value.as_string() != matched_capabilities.get_byte_string(name).value())
                 return AK::Error::from_string_view("browserName"sv);
         }
         // -> "browserVersion"
         else if (name == "browserVersion"sv) {
             // Compare value to the "browserVersion" entry in matched capabilities using an implementation-defined comparison algorithm. The comparison is to accept a value that places constraints on the version using the "<", "<=", ">", and ">=" operators.
             // If the two values do not match, return success with data null.
-            if (!matches_browser_version(value.as_string(), matched_capabilities.get_deprecated_string(name).value()))
+            if (!matches_browser_version(value.as_string(), matched_capabilities.get_byte_string(name).value()))
                 return AK::Error::from_string_view("browserVersion"sv);
         }
         // -> "platformName"
         else if (name == "platformName"sv) {
             // If value is not a string equal to the "platformName" entry in matched capabilities, return success with data null.
-            if (!matches_platform_name(value.as_string(), matched_capabilities.get_deprecated_string(name).value()))
+            if (!matches_platform_name(value.as_string(), matched_capabilities.get_byte_string(name).value()))
                 return AK::Error::from_string_view("platformName"sv);
         }
         // -> "acceptInsecureCerts"
diff --git a/Userland/Libraries/LibWeb/WebDriver/Client.cpp b/Userland/Libraries/LibWeb/WebDriver/Client.cpp
index 9b28f7efe46..fb9bd98ed98 100644
--- a/Userland/Libraries/LibWeb/WebDriver/Client.cpp
+++ b/Userland/Libraries/LibWeb/WebDriver/Client.cpp
@@ -270,7 +270,7 @@ ErrorOr<void, Client::WrappedError> Client::handle_request(JsonValue body)
     if constexpr (WEBDRIVER_DEBUG) {
         dbgln("Got HTTP request: {} {}", m_request->method_name(), m_request->resource());
         if (!body.is_null())
-            dbgln("Body: {}", body.to_deprecated_string());
+            dbgln("Body: {}", body.to_byte_string());
     }
 
     auto [handler, parameters] = TRY(match_route(*m_request));
@@ -345,7 +345,7 @@ ErrorOr<void, Client::WrappedError> Client::send_error_response(Error const& err
 
 void Client::log_response(unsigned code)
 {
-    outln("{} :: {:03d} :: {} {}", Core::DateTime::now().to_deprecated_string(), code, m_request->method_name(), m_request->resource());
+    outln("{} :: {:03d} :: {} {}", Core::DateTime::now().to_byte_string(), code, m_request->method_name(), m_request->resource());
 }
 
 }
diff --git a/Userland/Libraries/LibWeb/WebDriver/Contexts.cpp b/Userland/Libraries/LibWeb/WebDriver/Contexts.cpp
index a36b08df946..b20171c411b 100644
--- a/Userland/Libraries/LibWeb/WebDriver/Contexts.cpp
+++ b/Userland/Libraries/LibWeb/WebDriver/Contexts.cpp
@@ -25,7 +25,7 @@ JsonObject window_proxy_reference_object(HTML::WindowProxy const& window)
 
     // identifier
     //    Associated window handle of the window’s browsing context.
-    object.set(identifier, window.associated_browsing_context()->window_handle().to_deprecated_string());
+    object.set(identifier, window.associated_browsing_context()->window_handle().to_byte_string());
 
     return object;
 }
diff --git a/Userland/Libraries/LibWeb/WebDriver/Error.cpp b/Userland/Libraries/LibWeb/WebDriver/Error.cpp
index 6073a73fdc7..ad585dd357b 100644
--- a/Userland/Libraries/LibWeb/WebDriver/Error.cpp
+++ b/Userland/Libraries/LibWeb/WebDriver/Error.cpp
@@ -13,7 +13,7 @@ namespace Web::WebDriver {
 struct ErrorCodeData {
     ErrorCode error_code;
     unsigned http_status;
-    DeprecatedString json_error_code;
+    ByteString json_error_code;
 };
 
 // https://w3c.github.io/webdriver/#dfn-error-code
@@ -49,7 +49,7 @@ static Vector<ErrorCodeData> const s_error_code_data = {
     { ErrorCode::OutOfMemory, 500, "out of memory" },
 };
 
-Error Error::from_code(ErrorCode code, DeprecatedString message, Optional<JsonValue> data)
+Error Error::from_code(ErrorCode code, ByteString message, Optional<JsonValue> data)
 {
     auto const& error_code_data = s_error_code_data[to_underlying(code)];
 
@@ -67,7 +67,7 @@ Error::Error(AK::Error const& error)
     *this = from_code(ErrorCode::OutOfMemory, {}, {});
 }
 
-Error::Error(unsigned http_status_, DeprecatedString error_, DeprecatedString message_, Optional<JsonValue> data_)
+Error::Error(unsigned http_status_, ByteString error_, ByteString message_, Optional<JsonValue> data_)
     : http_status(http_status_)
     , error(move(error_))
     , message(move(message_))
diff --git a/Userland/Libraries/LibWeb/WebDriver/Error.h b/Userland/Libraries/LibWeb/WebDriver/Error.h
index fd5aaec2d31..31b216ad0e7 100644
--- a/Userland/Libraries/LibWeb/WebDriver/Error.h
+++ b/Userland/Libraries/LibWeb/WebDriver/Error.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/JsonValue.h>
 
 namespace Web::WebDriver {
@@ -50,13 +50,13 @@ enum class ErrorCode {
 // https://w3c.github.io/webdriver/#errors
 struct Error {
     unsigned http_status;
-    DeprecatedString error;
-    DeprecatedString message;
+    ByteString error;
+    ByteString message;
     Optional<JsonValue> data;
 
-    static Error from_code(ErrorCode, DeprecatedString message, Optional<JsonValue> data = {});
+    static Error from_code(ErrorCode, ByteString message, Optional<JsonValue> data = {});
 
-    Error(unsigned http_status, DeprecatedString error, DeprecatedString message, Optional<JsonValue> data);
+    Error(unsigned http_status, ByteString error, ByteString message, Optional<JsonValue> data);
     Error(AK::Error const&);
 };
 
@@ -66,6 +66,6 @@ template<>
 struct AK::Formatter<Web::WebDriver::Error> : Formatter<StringView> {
     ErrorOr<void> format(FormatBuilder& builder, Web::WebDriver::Error const& error)
     {
-        return Formatter<StringView>::format(builder, DeprecatedString::formatted("Error {}, {}: {}", error.http_status, error.error, error.message));
+        return Formatter<StringView>::format(builder, ByteString::formatted("Error {}, {}: {}", error.http_status, error.error, error.message));
     }
 };
diff --git a/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.cpp b/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.cpp
index 924d4426ddd..51e2ce1c7e9 100644
--- a/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.cpp
+++ b/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.cpp
@@ -99,7 +99,7 @@ static ErrorOr<JsonValue, ExecuteScriptResultType> internal_json_clone_algorithm
     if (value.is_number())
         return JsonValue { value.as_double() };
     if (value.is_string())
-        return JsonValue { value.as_string().deprecated_string() };
+        return JsonValue { value.as_string().byte_string() };
 
     // NOTE: BigInt and Symbol not mentioned anywhere in the WebDriver spec, as it references ES5.
     //       It assumes that all primitives are handled above, and the value is an object for the remaining steps.
@@ -130,7 +130,7 @@ static ErrorOr<JsonValue, ExecuteScriptResultType> internal_json_clone_algorithm
         auto to_json_result = TRY_OR_JS_ERROR(to_json.as_function().internal_call(value, JS::MarkedVector<JS::Value> { vm.heap() }));
         if (!to_json_result.is_string())
             return ExecuteScriptResultType::JavaScriptError;
-        return to_json_result.as_string().deprecated_string();
+        return to_json_result.as_string().byte_string();
     }
 
     // -> Otherwise
@@ -220,7 +220,7 @@ static ErrorOr<JsonValue, ExecuteScriptResultType> clone_an_object(JS::Realm& re
 }
 
 // https://w3c.github.io/webdriver/#dfn-execute-a-function-body
-static JS::ThrowCompletionOr<JS::Value> execute_a_function_body(Web::Page& page, DeprecatedString const& body, JS::MarkedVector<JS::Value> parameters)
+static JS::ThrowCompletionOr<JS::Value> execute_a_function_body(Web::Page& page, ByteString const& body, JS::MarkedVector<JS::Value> parameters)
 {
     // FIXME: If at any point during the algorithm a user prompt appears, immediately return Completion { [[Type]]: normal, [[Value]]: null, [[Target]]: empty }, but continue to run the other steps of this algorithm in parallel.
 
@@ -237,7 +237,7 @@ static JS::ThrowCompletionOr<JS::Value> execute_a_function_body(Web::Page& page,
     auto& realm = window.realm();
 
     bool contains_direct_call_to_eval = false;
-    auto source_text = DeprecatedString::formatted("function() {{ {} }}", body);
+    auto source_text = ByteString::formatted("function() {{ {} }}", body);
     auto parser = JS::Parser { JS::Lexer { source_text } };
     auto function_expression = parser.parse_function_node<JS::FunctionExpression>();
 
@@ -282,7 +282,7 @@ static JS::ThrowCompletionOr<JS::Value> execute_a_function_body(Web::Page& page,
     return completion;
 }
 
-ExecuteScriptResultSerialized execute_script(Web::Page& page, DeprecatedString const& body, JS::MarkedVector<JS::Value> arguments, Optional<u64> const& timeout)
+ExecuteScriptResultSerialized execute_script(Web::Page& page, ByteString const& body, JS::MarkedVector<JS::Value> arguments, Optional<u64> const& timeout)
 {
     // FIXME: Use timeout.
     (void)timeout;
@@ -323,7 +323,7 @@ ExecuteScriptResultSerialized execute_script(Web::Page& page, DeprecatedString c
     return { result.type, json_value_or_error.release_value() };
 }
 
-ExecuteScriptResultSerialized execute_async_script(Web::Page& page, DeprecatedString const& body, JS::MarkedVector<JS::Value> arguments, Optional<u64> const& timeout)
+ExecuteScriptResultSerialized execute_async_script(Web::Page& page, ByteString const& body, JS::MarkedVector<JS::Value> arguments, Optional<u64> const& timeout)
 {
     auto* document = page.top_level_browsing_context().active_document();
     auto* window = page.top_level_browsing_context().active_window();
diff --git a/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.h b/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.h
index 16b2ec7b5fc..0f2aeda8c23 100644
--- a/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.h
+++ b/Userland/Libraries/LibWeb/WebDriver/ExecuteScript.h
@@ -32,7 +32,7 @@ struct ExecuteScriptResultSerialized {
     JsonValue value;
 };
 
-ExecuteScriptResultSerialized execute_script(Page& page, DeprecatedString const& body, JS::MarkedVector<JS::Value> arguments, Optional<u64> const& timeout);
-ExecuteScriptResultSerialized execute_async_script(Page& page, DeprecatedString const& body, JS::MarkedVector<JS::Value> arguments, Optional<u64> const& timeout);
+ExecuteScriptResultSerialized execute_script(Page& page, ByteString const& body, JS::MarkedVector<JS::Value> arguments, Optional<u64> const& timeout);
+ExecuteScriptResultSerialized execute_async_script(Page& page, ByteString const& body, JS::MarkedVector<JS::Value> arguments, Optional<u64> const& timeout);
 
 }
diff --git a/Userland/Libraries/LibWeb/WebDriver/Response.cpp b/Userland/Libraries/LibWeb/WebDriver/Response.cpp
index eb54591db97..0e8cba136c0 100644
--- a/Userland/Libraries/LibWeb/WebDriver/Response.cpp
+++ b/Userland/Libraries/LibWeb/WebDriver/Response.cpp
@@ -58,8 +58,8 @@ ErrorOr<Web::WebDriver::Response> IPC::decode(Decoder& decoder)
 
     case ResponseType::Error: {
         auto http_status = TRY(decoder.decode<unsigned>());
-        auto error = TRY(decoder.decode<DeprecatedString>());
-        auto message = TRY(decoder.decode<DeprecatedString>());
+        auto error = TRY(decoder.decode<ByteString>());
+        auto message = TRY(decoder.decode<ByteString>());
         auto data = TRY(decoder.decode<Optional<JsonValue>>());
 
         return Web::WebDriver::Error { http_status, move(error), move(message), move(data) };
diff --git a/Userland/Libraries/LibWeb/WebGL/WebGLContextAttributes.cpp b/Userland/Libraries/LibWeb/WebGL/WebGLContextAttributes.cpp
index 331a396cb77..d66ecd01446 100644
--- a/Userland/Libraries/LibWeb/WebGL/WebGLContextAttributes.cpp
+++ b/Userland/Libraries/LibWeb/WebGL/WebGLContextAttributes.cpp
@@ -99,7 +99,7 @@ JS::ThrowCompletionOr<WebGLContextAttributes> convert_value_to_context_attribute
     WebGLPowerPreference power_preference_value { WebGLPowerPreference::Default };
 
     if (!power_preference.is_undefined()) {
-        auto power_preference_string = TRY(power_preference.to_deprecated_string(vm));
+        auto power_preference_string = TRY(power_preference.to_byte_string(vm));
 
         if (power_preference_string == "high-performance"sv)
             power_preference_value = WebGLPowerPreference::HighPerformance;
diff --git a/Userland/Libraries/LibWeb/WebIDL/AbstractOperations.cpp b/Userland/Libraries/LibWeb/WebIDL/AbstractOperations.cpp
index 6ff3360c2d6..3aa6393b547 100644
--- a/Userland/Libraries/LibWeb/WebIDL/AbstractOperations.cpp
+++ b/Userland/Libraries/LibWeb/WebIDL/AbstractOperations.cpp
@@ -147,7 +147,7 @@ JS::Completion call_user_object_operation(WebIDL::CallbackType& callback, String
     // 10. If ! IsCallable(O) is false, then:
     if (!object->is_function()) {
         // 1. Let getResult be Get(O, opName).
-        auto get_result = object->get(operation_name.to_deprecated_string());
+        auto get_result = object->get(operation_name.to_byte_string());
 
         // 2. If getResult is an abrupt completion, set completion to getResult and jump to the step labeled return.
         if (get_result.is_throw_completion()) {
@@ -318,7 +318,7 @@ JS::ThrowCompletionOr<bool> is_named_property_exposed_on_object(Variant<Bindings
     // 1. If P is not a supported property name of O, then return false.
     // NOTE: This is in it's own variable to enforce the type.
     Vector<String> supported_property_names = variant.visit([](auto* o) { return o->supported_property_names(); });
-    auto property_key_string = MUST(String::from_deprecated_string(property_key.to_string()));
+    auto property_key_string = MUST(String::from_byte_string(property_key.to_string()));
     if (!supported_property_names.contains_slow(property_key_string))
         return false;
 
diff --git a/Userland/Libraries/LibWeb/WebSockets/WebSocket.cpp b/Userland/Libraries/LibWeb/WebSockets/WebSocket.cpp
index 089eddf865f..7d7b21bc9eb 100644
--- a/Userland/Libraries/LibWeb/WebSockets/WebSocket.cpp
+++ b/Userland/Libraries/LibWeb/WebSockets/WebSocket.cpp
@@ -144,11 +144,11 @@ ErrorOr<void> WebSocket::establish_web_socket_connection(AK::URL& url_record, Ve
     auto& window = verify_cast<HTML::Window>(client.global_object());
     auto origin_string = window.associated_document().origin().serialize();
 
-    Vector<DeprecatedString> protcol_deprecated_strings;
+    Vector<ByteString> protcol_byte_strings;
     for (auto const& protocol : protocols)
-        TRY(protcol_deprecated_strings.try_append(protocol.to_deprecated_string()));
+        TRY(protcol_byte_strings.try_append(protocol.to_byte_string()));
 
-    m_websocket = WebSocketClientManager::the().connect(url_record, origin_string, protcol_deprecated_strings);
+    m_websocket = WebSocketClientManager::the().connect(url_record, origin_string, protcol_byte_strings);
     m_websocket->on_open = [weak_this = make_weak_ptr<WebSocket>()] {
         if (!weak_this)
             return;
@@ -165,7 +165,7 @@ ErrorOr<void> WebSocket::establish_web_socket_connection(AK::URL& url_record, Ve
         if (!weak_this)
             return;
         auto& websocket = const_cast<WebSocket&>(*weak_this);
-        websocket.on_close(code, String::from_deprecated_string(reason).release_value_but_fixme_should_propagate_errors(), was_clean);
+        websocket.on_close(code, String::from_byte_string(reason).release_value_but_fixme_should_propagate_errors(), was_clean);
     };
     m_websocket->on_error = [weak_this = make_weak_ptr<WebSocket>()](auto) {
         if (!weak_this)
@@ -200,7 +200,7 @@ WebIDL::ExceptionOr<String> WebSocket::protocol() const
 {
     if (!m_websocket)
         return String {};
-    return TRY_OR_THROW_OOM(vm(), String::from_deprecated_string(m_websocket->subprotocol_in_use()));
+    return TRY_OR_THROW_OOM(vm(), String::from_byte_string(m_websocket->subprotocol_in_use()));
 }
 
 // https://websockets.spec.whatwg.org/#dom-websocket-close
@@ -226,7 +226,7 @@ WebIDL::ExceptionOr<void> WebSocket::close(Optional<u16> code, Optional<String>
     // -> Otherwise
     // NOTE: All of these are handled by the WebSocket Protocol when calling close()
     // FIXME: LibProtocol does not yet support sending empty Close messages, so we use default values for now
-    m_websocket->close(code.value_or(1000), reason.value_or(String {}).to_deprecated_string());
+    m_websocket->close(code.value_or(1000), reason.value_or(String {}).to_byte_string());
     return {};
 }
 
@@ -294,7 +294,7 @@ void WebSocket::on_message(ByteBuffer message, bool is_text)
     if (m_websocket->ready_state() != WebSocket::ReadyState::Open)
         return;
     if (is_text) {
-        auto text_message = DeprecatedString(ReadonlyBytes(message));
+        auto text_message = ByteString(ReadonlyBytes(message));
         HTML::MessageEventInit event_init;
         event_init.data = JS::PrimitiveString::create(vm(), text_message);
         event_init.origin = url().release_value_but_fixme_should_propagate_errors();
diff --git a/Userland/Libraries/LibWeb/WebSockets/WebSocket.h b/Userland/Libraries/LibWeb/WebSockets/WebSocket.h
index ec71e305ec7..1d102c815b9 100644
--- a/Userland/Libraries/LibWeb/WebSockets/WebSocket.h
+++ b/Userland/Libraries/LibWeb/WebSockets/WebSocket.h
@@ -85,8 +85,8 @@ public:
     virtual ~WebSocketClientSocket();
 
     struct CertificateAndKey {
-        DeprecatedString certificate;
-        DeprecatedString key;
+        ByteString certificate;
+        ByteString key;
     };
 
     struct Message {
@@ -101,16 +101,16 @@ public:
     };
 
     virtual Web::WebSockets::WebSocket::ReadyState ready_state() = 0;
-    virtual DeprecatedString subprotocol_in_use() = 0;
+    virtual ByteString subprotocol_in_use() = 0;
 
     virtual void send(ByteBuffer binary_or_text_message, bool is_text) = 0;
     virtual void send(StringView text_message) = 0;
-    virtual void close(u16 code = 1005, DeprecatedString reason = {}) = 0;
+    virtual void close(u16 code = 1005, ByteString reason = {}) = 0;
 
     Function<void()> on_open;
     Function<void(Message)> on_message;
     Function<void(Error)> on_error;
-    Function<void(u16 code, DeprecatedString reason, bool was_clean)> on_close;
+    Function<void(u16 code, ByteString reason, bool was_clean)> on_close;
     Function<CertificateAndKey()> on_certificate_requested;
 
 protected:
@@ -123,7 +123,7 @@ public:
     static void initialize(RefPtr<WebSocketClientManager>);
     static WebSocketClientManager& the();
 
-    virtual RefPtr<WebSocketClientSocket> connect(AK::URL const&, DeprecatedString const& origin, Vector<DeprecatedString> const& protocols) = 0;
+    virtual RefPtr<WebSocketClientSocket> connect(AK::URL const&, ByteString const& origin, Vector<ByteString> const& protocols) = 0;
 
 protected:
     explicit WebSocketClientManager();
diff --git a/Userland/Libraries/LibWeb/XHR/XMLHttpRequest.cpp b/Userland/Libraries/LibWeb/XHR/XMLHttpRequest.cpp
index ceafda130e2..505ea96d839 100644
--- a/Userland/Libraries/LibWeb/XHR/XMLHttpRequest.cpp
+++ b/Userland/Libraries/LibWeb/XHR/XMLHttpRequest.cpp
@@ -305,7 +305,7 @@ void XMLHttpRequest::set_document_response()
         document = DOM::Document::create(realm());
         if (!charset.has_value())
             if (auto found_charset = HTML::run_prescan_byte_stream_algorithm(*document, m_received_bytes); found_charset.has_value())
-                charset = MUST(String::from_deprecated_string(found_charset.value())).bytes_as_string_view();
+                charset = MUST(String::from_byte_string(found_charset.value())).bytes_as_string_view();
 
         // 5.3. If charset is null, then set charset to UTF-8.
         if (!charset.has_value())
diff --git a/Userland/Libraries/LibWeb/XHR/XMLHttpRequest.h b/Userland/Libraries/LibWeb/XHR/XMLHttpRequest.h
index 8e49692db8f..1ab202b2902 100644
--- a/Userland/Libraries/LibWeb/XHR/XMLHttpRequest.h
+++ b/Userland/Libraries/LibWeb/XHR/XMLHttpRequest.h
@@ -124,7 +124,7 @@ private:
     // https://xhr.spec.whatwg.org/#request-method
     // request method
     //     A method.
-    DeprecatedString m_request_method;
+    ByteString m_request_method;
 
     // https://xhr.spec.whatwg.org/#request-url
     // request URL
diff --git a/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp b/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp
index e08c79ce8dc..2c3186e9cfd 100644
--- a/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp
+++ b/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.cpp
@@ -16,7 +16,7 @@ extern char const* s_xhtml_unified_dtd;
 
 namespace Web {
 
-ErrorOr<DeprecatedString> resolve_xml_resource(XML::SystemID const&, Optional<XML::PublicID> const& public_id)
+ErrorOr<ByteString> resolve_xml_resource(XML::SystemID const&, Optional<XML::PublicID> const& public_id)
 {
     if (!public_id.has_value())
         return Error::from_string_literal("Refusing to load disallowed external entity");
@@ -45,12 +45,12 @@ XMLDocumentBuilder::XMLDocumentBuilder(DOM::Document& document, XMLScriptingSupp
     m_namespace_stack.append({ m_namespace, 1 });
 }
 
-void XMLDocumentBuilder::set_source(DeprecatedString source)
+void XMLDocumentBuilder::set_source(ByteString source)
 {
-    m_document->set_source(MUST(String::from_deprecated_string(source)));
+    m_document->set_source(MUST(String::from_byte_string(source)));
 }
 
-void XMLDocumentBuilder::element_start(const XML::Name& name, HashMap<XML::Name, DeprecatedString> const& attributes)
+void XMLDocumentBuilder::element_start(const XML::Name& name, HashMap<XML::Name, ByteString> const& attributes)
 {
     if (m_has_error)
         return;
@@ -85,7 +85,7 @@ void XMLDocumentBuilder::element_start(const XML::Name& name, HashMap<XML::Name,
     }
 
     for (auto const& attribute : attributes)
-        MUST(node->set_attribute(MUST(FlyString::from_deprecated_fly_string(attribute.key)), MUST(String::from_deprecated_string(attribute.value))));
+        MUST(node->set_attribute(MUST(FlyString::from_deprecated_fly_string(attribute.key)), MUST(String::from_byte_string(attribute.value))));
 
     m_current_node = node.ptr();
 }
@@ -144,11 +144,11 @@ void XMLDocumentBuilder::text(StringView data)
         text_node.set_data(MUST(text_builder.to_string()));
         text_builder.clear();
     } else {
-        auto string = DeprecatedString::empty();
+        auto string = ByteString::empty();
         if (!data.is_null())
-            string = data.to_deprecated_string();
+            string = data.to_byte_string();
         if (!string.is_empty()) {
-            auto node = m_document->create_text_node(MUST(String::from_deprecated_string(string)));
+            auto node = m_document->create_text_node(MUST(String::from_byte_string(string)));
             MUST(m_current_node->append_child(node));
         }
     }
@@ -158,10 +158,10 @@ void XMLDocumentBuilder::comment(StringView data)
 {
     if (m_has_error)
         return;
-    auto string = DeprecatedString::empty();
+    auto string = ByteString::empty();
     if (!data.is_null())
-        string = data.to_deprecated_string();
-    MUST(m_document->append_child(m_document->create_comment(MUST(String::from_deprecated_string(string)))));
+        string = data.to_byte_string();
+    MUST(m_document->append_child(m_document->create_comment(MUST(String::from_byte_string(string)))));
 }
 
 void XMLDocumentBuilder::document_end()
diff --git a/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.h b/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.h
index c7f293e090c..033f15c0eaa 100644
--- a/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.h
+++ b/Userland/Libraries/LibWeb/XML/XMLDocumentBuilder.h
@@ -21,7 +21,7 @@ enum class XMLScriptingSupport {
     Enabled,
 };
 
-ErrorOr<DeprecatedString> resolve_xml_resource(XML::SystemID const&, Optional<XML::PublicID> const&);
+ErrorOr<ByteString> resolve_xml_resource(XML::SystemID const&, Optional<XML::PublicID> const&);
 
 class XMLDocumentBuilder final : public XML::Listener {
 public:
@@ -30,8 +30,8 @@ public:
     bool has_error() const { return m_has_error; }
 
 private:
-    virtual void set_source(DeprecatedString) override;
-    virtual void element_start(XML::Name const& name, HashMap<XML::Name, DeprecatedString> const& attributes) override;
+    virtual void set_source(ByteString) override;
+    virtual void element_start(XML::Name const& name, HashMap<XML::Name, ByteString> const& attributes) override;
     virtual void element_end(XML::Name const& name) override;
     virtual void text(StringView data) override;
     virtual void comment(StringView data) override;
diff --git a/Userland/Libraries/LibWebSocket/ConnectionInfo.cpp b/Userland/Libraries/LibWebSocket/ConnectionInfo.cpp
index dfae4baf477..7446f97dc3e 100644
--- a/Userland/Libraries/LibWebSocket/ConnectionInfo.cpp
+++ b/Userland/Libraries/LibWebSocket/ConnectionInfo.cpp
@@ -20,7 +20,7 @@ bool ConnectionInfo::is_secure() const
     return m_url.scheme().bytes_as_string_view().equals_ignoring_ascii_case("wss"sv);
 }
 
-DeprecatedString ConnectionInfo::resource_name() const
+ByteString ConnectionInfo::resource_name() const
 {
     // RFC 6455 Section 3 :
     // The "resource-name" can be constructed by concatenating the following:
@@ -37,7 +37,7 @@ DeprecatedString ConnectionInfo::resource_name() const
         // the query component
         builder.append(*m_url.query());
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 }
diff --git a/Userland/Libraries/LibWebSocket/ConnectionInfo.h b/Userland/Libraries/LibWebSocket/ConnectionInfo.h
index 8df7cf047ba..c4764102d6c 100644
--- a/Userland/Libraries/LibWebSocket/ConnectionInfo.h
+++ b/Userland/Libraries/LibWebSocket/ConnectionInfo.h
@@ -20,18 +20,18 @@ public:
 
     URL const& url() const { return m_url; }
 
-    DeprecatedString const& origin() const { return m_origin; }
-    void set_origin(DeprecatedString origin) { m_origin = move(origin); }
+    ByteString const& origin() const { return m_origin; }
+    void set_origin(ByteString origin) { m_origin = move(origin); }
 
-    Vector<DeprecatedString> const& protocols() const { return m_protocols; }
-    void set_protocols(Vector<DeprecatedString> protocols) { m_protocols = move(protocols); }
+    Vector<ByteString> const& protocols() const { return m_protocols; }
+    void set_protocols(Vector<ByteString> protocols) { m_protocols = move(protocols); }
 
-    Vector<DeprecatedString> const& extensions() const { return m_extensions; }
-    void set_extensions(Vector<DeprecatedString> extensions) { m_extensions = move(extensions); }
+    Vector<ByteString> const& extensions() const { return m_extensions; }
+    void set_extensions(Vector<ByteString> extensions) { m_extensions = move(extensions); }
 
     struct Header {
-        DeprecatedString name;
-        DeprecatedString value;
+        ByteString name;
+        ByteString value;
     };
     Vector<Header> const& headers() const { return m_headers; }
     void set_headers(Vector<Header> headers) { m_headers = move(headers); }
@@ -40,13 +40,13 @@ public:
     bool is_secure() const;
 
     // "resource-name" or "/resource name/" - defined in RFC 6455 Section 3
-    DeprecatedString resource_name() const;
+    ByteString resource_name() const;
 
 private:
     URL m_url;
-    DeprecatedString m_origin;
-    Vector<DeprecatedString> m_protocols {};
-    Vector<DeprecatedString> m_extensions {};
+    ByteString m_origin;
+    Vector<ByteString> m_protocols {};
+    Vector<ByteString> m_extensions {};
     Vector<Header> m_headers {};
 };
 
diff --git a/Userland/Libraries/LibWebSocket/Impl/WebSocketImpl.h b/Userland/Libraries/LibWebSocket/Impl/WebSocketImpl.h
index 84204bd3c98..7ce8b56ef16 100644
--- a/Userland/Libraries/LibWebSocket/Impl/WebSocketImpl.h
+++ b/Userland/Libraries/LibWebSocket/Impl/WebSocketImpl.h
@@ -9,7 +9,7 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Span.h>
 #include <LibWebSocket/ConnectionInfo.h>
 
@@ -21,7 +21,7 @@ public:
 
     virtual void connect(ConnectionInfo const&) = 0;
     virtual bool can_read_line() = 0;
-    virtual ErrorOr<DeprecatedString> read_line(size_t) = 0;
+    virtual ErrorOr<ByteString> read_line(size_t) = 0;
     virtual ErrorOr<ByteBuffer> read(int max_size) = 0;
     virtual bool send(ReadonlyBytes) = 0;
     virtual bool eof() = 0;
diff --git a/Userland/Libraries/LibWebSocket/Impl/WebSocketImplSerenity.cpp b/Userland/Libraries/LibWebSocket/Impl/WebSocketImplSerenity.cpp
index 80593e3c187..3aa0d5cf416 100644
--- a/Userland/Libraries/LibWebSocket/Impl/WebSocketImplSerenity.cpp
+++ b/Userland/Libraries/LibWebSocket/Impl/WebSocketImplSerenity.cpp
@@ -42,7 +42,7 @@ void WebSocketImplSerenity::connect(ConnectionInfo const& connection_info)
     VERIFY(on_connection_error);
     VERIFY(on_ready_to_read);
     auto socket_result = [&]() -> ErrorOr<NonnullOwnPtr<Core::BufferedSocketBase>> {
-        auto host = TRY(connection_info.url().serialized_host()).to_deprecated_string();
+        auto host = TRY(connection_info.url().serialized_host()).to_byte_string();
         if (connection_info.is_secure()) {
             TLS::Options options;
             options.set_alert_handler([this](auto) {
@@ -82,11 +82,11 @@ ErrorOr<ByteBuffer> WebSocketImplSerenity::read(int max_size)
     return buffer.slice(0, read_bytes.size());
 }
 
-ErrorOr<DeprecatedString> WebSocketImplSerenity::read_line(size_t size)
+ErrorOr<ByteString> WebSocketImplSerenity::read_line(size_t size)
 {
     auto buffer = TRY(ByteBuffer::create_uninitialized(size));
     auto line = TRY(m_socket->read_line(buffer));
-    return line.to_deprecated_string();
+    return line.to_byte_string();
 }
 
 }
diff --git a/Userland/Libraries/LibWebSocket/Impl/WebSocketImplSerenity.h b/Userland/Libraries/LibWebSocket/Impl/WebSocketImplSerenity.h
index a475898dbd5..bb165e0516b 100644
--- a/Userland/Libraries/LibWebSocket/Impl/WebSocketImplSerenity.h
+++ b/Userland/Libraries/LibWebSocket/Impl/WebSocketImplSerenity.h
@@ -19,7 +19,7 @@ public:
 
     virtual void connect(ConnectionInfo const&) override;
     virtual bool can_read_line() override;
-    virtual ErrorOr<DeprecatedString> read_line(size_t) override;
+    virtual ErrorOr<ByteString> read_line(size_t) override;
     virtual ErrorOr<ByteBuffer> read(int max_size) override;
     virtual bool send(ReadonlyBytes) override;
     virtual bool eof() override;
diff --git a/Userland/Libraries/LibWebSocket/Message.h b/Userland/Libraries/LibWebSocket/Message.h
index 8ee230fecc8..811d037faf8 100644
--- a/Userland/Libraries/LibWebSocket/Message.h
+++ b/Userland/Libraries/LibWebSocket/Message.h
@@ -7,14 +7,14 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 
 namespace WebSocket {
 
 class Message {
 public:
-    explicit Message(DeprecatedString const& data)
+    explicit Message(ByteString const& data)
         : m_is_text(true)
         , m_data(ByteBuffer::copy(data.bytes()).release_value_but_fixme_should_propagate_errors()) // FIXME: Handle possible OOM situation.
     {
diff --git a/Userland/Libraries/LibWebSocket/WebSocket.cpp b/Userland/Libraries/LibWebSocket/WebSocket.cpp
index a944c140501..5957efc18bb 100644
--- a/Userland/Libraries/LibWebSocket/WebSocket.cpp
+++ b/Userland/Libraries/LibWebSocket/WebSocket.cpp
@@ -74,7 +74,7 @@ ReadyState WebSocket::ready_state()
     }
 }
 
-DeprecatedString WebSocket::subprotocol_in_use()
+ByteString WebSocket::subprotocol_in_use()
 {
     return m_subprotocol_in_use;
 }
@@ -90,7 +90,7 @@ void WebSocket::send(Message const& message)
         send_frame(WebSocket::OpCode::Binary, message.data(), true);
 }
 
-void WebSocket::close(u16 code, DeprecatedString const& message)
+void WebSocket::close(u16 code, ByteString const& message)
 {
     VERIFY(m_impl);
 
@@ -186,7 +186,7 @@ void WebSocket::send_client_handshake()
     u8 nonce_data[16];
     fill_with_random(nonce_data);
     // FIXME: change to TRY() and make method fallible
-    m_websocket_key = MUST(encode_base64({ nonce_data, 16 })).to_deprecated_string();
+    m_websocket_key = MUST(encode_base64({ nonce_data, 16 })).to_byte_string();
     builder.appendff("Sec-WebSocket-Key: {}\r\n", m_websocket_key);
 
     // 8. Origin (optional field)
@@ -219,7 +219,7 @@ void WebSocket::send_client_handshake()
     builder.append("\r\n"sv);
 
     m_state = WebSocket::InternalState::WaitingForServerHandshake;
-    auto success = m_impl->send(builder.to_deprecated_string().bytes());
+    auto success = m_impl->send(builder.to_byte_string().bytes());
     VERIFY(success);
 }
 
@@ -322,7 +322,7 @@ void WebSocket::read_server_handshake()
 
         if (header_name.equals_ignoring_ascii_case("Sec-WebSocket-Accept"sv)) {
             // 4. |Sec-WebSocket-Accept| should be base64(SHA1(|Sec-WebSocket-Key| + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"))
-            auto expected_content = DeprecatedString::formatted("{}258EAFA5-E914-47DA-95CA-C5AB0DC85B11", m_websocket_key);
+            auto expected_content = ByteString::formatted("{}258EAFA5-E914-47DA-95CA-C5AB0DC85B11", m_websocket_key);
 
             Crypto::Hash::Manager hash;
             hash.initialize(Crypto::Hash::HashKind::SHA1);
@@ -485,7 +485,7 @@ void WebSocket::read_frame()
     if (op_code == WebSocket::OpCode::ConnectionClose) {
         if (payload.size() > 1) {
             m_last_close_code = (((u16)(payload[0] & 0xff) << 8) | ((u16)(payload[1] & 0xff)));
-            m_last_close_message = DeprecatedString(ReadonlyBytes(payload.offset_pointer(2), payload.size() - 2));
+            m_last_close_message = ByteString(ReadonlyBytes(payload.offset_pointer(2), payload.size() - 2));
         }
         m_state = WebSocket::InternalState::Closing;
         return;
@@ -632,7 +632,7 @@ void WebSocket::notify_open()
     on_open();
 }
 
-void WebSocket::notify_close(u16 code, DeprecatedString reason, bool was_clean)
+void WebSocket::notify_close(u16 code, ByteString reason, bool was_clean)
 {
     if (!on_close)
         return;
diff --git a/Userland/Libraries/LibWebSocket/WebSocket.h b/Userland/Libraries/LibWebSocket/WebSocket.h
index 9f6f3952368..11aefd87057 100644
--- a/Userland/Libraries/LibWebSocket/WebSocket.h
+++ b/Userland/Libraries/LibWebSocket/WebSocket.h
@@ -32,7 +32,7 @@ public:
 
     ReadyState ready_state();
 
-    DeprecatedString subprotocol_in_use();
+    ByteString subprotocol_in_use();
 
     // Call this to start the WebSocket connection.
     void start();
@@ -41,10 +41,10 @@ public:
     void send(Message const&);
 
     // This can only be used if the `ready_state` is `ReadyState::Open`
-    void close(u16 code = 1005, DeprecatedString const& reason = {});
+    void close(u16 code = 1005, ByteString const& reason = {});
 
     Function<void()> on_open;
-    Function<void(u16 code, DeprecatedString reason, bool was_clean)> on_close;
+    Function<void(u16 code, ByteString reason, bool was_clean)> on_close;
     Function<void(Message message)> on_message;
 
     enum class Error {
@@ -77,7 +77,7 @@ private:
     void send_frame(OpCode, ReadonlyBytes, bool is_final);
 
     void notify_open();
-    void notify_close(u16 code, DeprecatedString reason, bool was_clean);
+    void notify_close(u16 code, ByteString reason, bool was_clean);
     void notify_error(Error);
     void notify_message(Message);
 
@@ -97,16 +97,16 @@ private:
 
     InternalState m_state { InternalState::NotStarted };
 
-    DeprecatedString m_subprotocol_in_use { DeprecatedString::empty() };
+    ByteString m_subprotocol_in_use { ByteString::empty() };
 
-    DeprecatedString m_websocket_key;
+    ByteString m_websocket_key;
     bool m_has_read_server_handshake_first_line { false };
     bool m_has_read_server_handshake_upgrade { false };
     bool m_has_read_server_handshake_connection { false };
     bool m_has_read_server_handshake_accept { false };
 
     u16 m_last_close_code { 1005 };
-    DeprecatedString m_last_close_message;
+    ByteString m_last_close_message;
 
     ConnectionInfo m_connection;
     RefPtr<WebSocketImpl> m_impl;
diff --git a/Userland/Libraries/LibWebView/CookieJar.cpp b/Userland/Libraries/LibWebView/CookieJar.cpp
index 55f7a2c8514..1688d1693ea 100644
--- a/Userland/Libraries/LibWebView/CookieJar.cpp
+++ b/Userland/Libraries/LibWebView/CookieJar.cpp
@@ -81,7 +81,7 @@ CookieJar::CookieJar(TransientStorage storage)
 {
 }
 
-DeprecatedString CookieJar::get_cookie(const URL& url, Web::Cookie::Source source)
+ByteString CookieJar::get_cookie(const URL& url, Web::Cookie::Source source)
 {
     purge_expired_cookies();
 
@@ -101,7 +101,7 @@ DeprecatedString CookieJar::get_cookie(const URL& url, Web::Cookie::Source sourc
         builder.appendff("{}={}", cookie.name, cookie.value);
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 void CookieJar::set_cookie(const URL& url, Web::Cookie::ParsedCookie const& parsed_cookie, Web::Cookie::Source source)
@@ -163,7 +163,7 @@ void CookieJar::dump_cookies()
         builder.appendff("\t{}SameSite{} = {:s}\n", attribute_color, no_color, Web::Cookie::same_site_to_string(cookie.same_site));
     });
 
-    dbgln("{} cookies stored\n{}", total_cookies, builder.to_deprecated_string());
+    dbgln("{} cookies stored\n{}", total_cookies, builder.to_byte_string());
 }
 
 Vector<Web::Cookie::Cookie> CookieJar::get_all_cookies()
@@ -187,7 +187,7 @@ Vector<Web::Cookie::Cookie> CookieJar::get_all_cookies(URL const& url)
     return get_matching_cookies(url, domain.value(), Web::Cookie::Source::Http, MatchingCookiesSpecMode::WebDriver);
 }
 
-Optional<Web::Cookie::Cookie> CookieJar::get_named_cookie(URL const& url, DeprecatedString const& name)
+Optional<Web::Cookie::Cookie> CookieJar::get_named_cookie(URL const& url, ByteString const& name)
 {
     auto domain = canonicalize_domain(url);
     if (!domain.has_value())
@@ -203,7 +203,7 @@ Optional<Web::Cookie::Cookie> CookieJar::get_named_cookie(URL const& url, Deprec
     return {};
 }
 
-Optional<DeprecatedString> CookieJar::canonicalize_domain(const URL& url)
+Optional<ByteString> CookieJar::canonicalize_domain(const URL& url)
 {
     // https://tools.ietf.org/html/rfc6265#section-5.1.2
     if (!url.is_valid())
@@ -213,10 +213,10 @@ Optional<DeprecatedString> CookieJar::canonicalize_domain(const URL& url)
     if (url.host().has<Empty>())
         return {};
 
-    return url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string().to_lowercase();
+    return url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string().to_lowercase();
 }
 
-bool CookieJar::domain_matches(DeprecatedString const& string, DeprecatedString const& domain_string)
+bool CookieJar::domain_matches(ByteString const& string, ByteString const& domain_string)
 {
     // https://tools.ietf.org/html/rfc6265#section-5.1.3
 
@@ -240,7 +240,7 @@ bool CookieJar::domain_matches(DeprecatedString const& string, DeprecatedString
     return true;
 }
 
-bool CookieJar::path_matches(DeprecatedString const& request_path, DeprecatedString const& cookie_path)
+bool CookieJar::path_matches(ByteString const& request_path, ByteString const& cookie_path)
 {
     // https://tools.ietf.org/html/rfc6265#section-5.1.4
 
@@ -263,12 +263,12 @@ bool CookieJar::path_matches(DeprecatedString const& request_path, DeprecatedStr
     return false;
 }
 
-DeprecatedString CookieJar::default_path(const URL& url)
+ByteString CookieJar::default_path(const URL& url)
 {
     // https://tools.ietf.org/html/rfc6265#section-5.1.4
 
     // 1. Let uri-path be the path portion of the request-uri if such a portion exists (and empty otherwise).
-    DeprecatedString uri_path = url.serialize_path();
+    ByteString uri_path = url.serialize_path();
 
     // 2. If the uri-path is empty or if the first character of the uri-path is not a %x2F ("/") character, output %x2F ("/") and skip the remaining steps.
     if (uri_path.is_empty() || (uri_path[0] != '/'))
@@ -285,7 +285,7 @@ DeprecatedString CookieJar::default_path(const URL& url)
     return uri_path.substring(0, last_separator);
 }
 
-void CookieJar::store_cookie(Web::Cookie::ParsedCookie const& parsed_cookie, const URL& url, DeprecatedString canonicalized_domain, Web::Cookie::Source source)
+void CookieJar::store_cookie(Web::Cookie::ParsedCookie const& parsed_cookie, const URL& url, ByteString canonicalized_domain, Web::Cookie::Source source)
 {
     // https://tools.ietf.org/html/rfc6265#section-5.3
 
@@ -333,7 +333,7 @@ void CookieJar::store_cookie(Web::Cookie::ParsedCookie const& parsed_cookie, con
     // 6. If the domain-attribute is non-empty:
     if (!cookie.domain.is_empty()) {
         // If the canonicalized request-host does not domain-match the domain-attribute: Ignore the cookie entirely and abort these steps.
-        if (!domain_matches(canonicalized_domain, cookie.domain.to_deprecated_string()))
+        if (!domain_matches(canonicalized_domain, cookie.domain.to_byte_string()))
             return;
 
         // Set the cookie's host-only-flag to false. Set the cookie's domain to the domain-attribute.
@@ -341,7 +341,7 @@ void CookieJar::store_cookie(Web::Cookie::ParsedCookie const& parsed_cookie, con
     } else {
         // Set the cookie's host-only-flag to true. Set the cookie's domain to the canonicalized request-host.
         cookie.host_only = true;
-        cookie.domain = MUST(String::from_deprecated_string(canonicalized_domain));
+        cookie.domain = MUST(String::from_byte_string(canonicalized_domain));
     }
 
     // 7. If the cookie-attribute-list contains an attribute with an attribute-name of "Path":
@@ -349,7 +349,7 @@ void CookieJar::store_cookie(Web::Cookie::ParsedCookie const& parsed_cookie, con
         // Set the cookie's path to attribute-value of the last attribute in the cookie-attribute-list with an attribute-name of "Path".
         cookie.path = parsed_cookie.path.value();
     } else {
-        cookie.path = MUST(String::from_deprecated_string(default_path(url)));
+        cookie.path = MUST(String::from_byte_string(default_path(url)));
     }
 
     // 8. If the cookie-attribute-list contains an attribute with an attribute-name of "Secure", set the cookie's secure-only-flag to true.
@@ -393,7 +393,7 @@ void CookieJar::store_cookie(Web::Cookie::ParsedCookie const& parsed_cookie, con
     MUST(sync_promise->await());
 }
 
-Vector<Web::Cookie::Cookie> CookieJar::get_matching_cookies(const URL& url, DeprecatedString const& canonicalized_domain, Web::Cookie::Source source, MatchingCookiesSpecMode mode)
+Vector<Web::Cookie::Cookie> CookieJar::get_matching_cookies(const URL& url, ByteString const& canonicalized_domain, Web::Cookie::Source source, MatchingCookiesSpecMode mode)
 {
     // https://tools.ietf.org/html/rfc6265#section-5.4
 
@@ -404,12 +404,12 @@ Vector<Web::Cookie::Cookie> CookieJar::get_matching_cookies(const URL& url, Depr
         // Either: The cookie's host-only-flag is true and the canonicalized request-host is identical to the cookie's domain.
         // Or: The cookie's host-only-flag is false and the canonicalized request-host domain-matches the cookie's domain.
         bool is_host_only_and_has_identical_domain = cookie.host_only && (canonicalized_domain.view() == cookie.domain);
-        bool is_not_host_only_and_domain_matches = !cookie.host_only && domain_matches(canonicalized_domain, cookie.domain.to_deprecated_string());
+        bool is_not_host_only_and_domain_matches = !cookie.host_only && domain_matches(canonicalized_domain, cookie.domain.to_byte_string());
         if (!is_host_only_and_has_identical_domain && !is_not_host_only_and_domain_matches)
             return;
 
         // The request-uri's path path-matches the cookie's path.
-        if (!path_matches(url.serialize_path(), cookie.path.to_deprecated_string()))
+        if (!path_matches(url.serialize_path(), cookie.path.to_byte_string()))
             return;
 
         // If the cookie's secure-only-flag is true, then the request-uri's scheme must denote a "secure" protocol.
@@ -466,7 +466,7 @@ static ErrorOr<Web::Cookie::Cookie> parse_cookie(ReadonlySpan<SQL::Value> row)
         if (value.type() != SQL::SQLType::Text)
             return Error::from_string_view(name);
 
-        field = MUST(String::from_deprecated_string(value.to_deprecated_string()));
+        field = MUST(String::from_byte_string(value.to_byte_string()));
         return {};
     };
 
@@ -525,21 +525,21 @@ void CookieJar::insert_cookie_into_database(Web::Cookie::Cookie const& cookie)
         [&](PersistedStorage& storage) {
             storage.database.execute_statement(
                 storage.statements.insert_cookie, {}, [this]() { purge_expired_cookies(); }, {},
-                cookie.name.to_deprecated_string(),
-                cookie.value.to_deprecated_string(),
+                cookie.name.to_byte_string(),
+                cookie.value.to_byte_string(),
                 to_underlying(cookie.same_site),
                 cookie.creation_time.seconds_since_epoch(),
                 cookie.last_access_time.seconds_since_epoch(),
                 cookie.expiry_time.seconds_since_epoch(),
-                cookie.domain.to_deprecated_string(),
-                cookie.path.to_deprecated_string(),
+                cookie.domain.to_byte_string(),
+                cookie.path.to_byte_string(),
                 cookie.secure,
                 cookie.http_only,
                 cookie.host_only,
                 cookie.persistent);
         },
         [&](TransientStorage& storage) {
-            CookieStorageKey key { cookie.name.to_deprecated_string(), cookie.domain.to_deprecated_string(), cookie.path.to_deprecated_string() };
+            CookieStorageKey key { cookie.name.to_byte_string(), cookie.domain.to_byte_string(), cookie.path.to_byte_string() };
             storage.set(key, cookie);
         });
 }
@@ -550,7 +550,7 @@ void CookieJar::update_cookie_in_database(Web::Cookie::Cookie const& cookie)
         [&](PersistedStorage& storage) {
             storage.database.execute_statement(
                 storage.statements.update_cookie, {}, [this]() { purge_expired_cookies(); }, {},
-                cookie.value.to_deprecated_string(),
+                cookie.value.to_byte_string(),
                 to_underlying(cookie.same_site),
                 cookie.creation_time.seconds_since_epoch(),
                 cookie.last_access_time.seconds_since_epoch(),
@@ -559,12 +559,12 @@ void CookieJar::update_cookie_in_database(Web::Cookie::Cookie const& cookie)
                 cookie.http_only,
                 cookie.host_only,
                 cookie.persistent,
-                cookie.name.to_deprecated_string(),
-                cookie.domain.to_deprecated_string(),
-                cookie.path.to_deprecated_string());
+                cookie.name.to_byte_string(),
+                cookie.domain.to_byte_string(),
+                cookie.path.to_byte_string());
         },
         [&](TransientStorage& storage) {
-            CookieStorageKey key { cookie.name.to_deprecated_string(), cookie.domain.to_deprecated_string(), cookie.path.to_deprecated_string() };
+            CookieStorageKey key { cookie.name.to_byte_string(), cookie.domain.to_byte_string(), cookie.path.to_byte_string() };
             storage.set(key, cookie);
         });
 }
@@ -601,12 +601,12 @@ void CookieJar::select_cookie_from_database(Web::Cookie::Cookie cookie, OnCookie
                         on_complete_without_results(move(wrapped_cookie->cookie));
                 },
                 {},
-                wrapped_cookie->cookie.name.to_deprecated_string(),
-                wrapped_cookie->cookie.domain.to_deprecated_string(),
-                wrapped_cookie->cookie.path.to_deprecated_string());
+                wrapped_cookie->cookie.name.to_byte_string(),
+                wrapped_cookie->cookie.domain.to_byte_string(),
+                wrapped_cookie->cookie.path.to_byte_string());
         },
         [&](TransientStorage& storage) {
-            CookieStorageKey key { cookie.name.to_deprecated_string(), cookie.domain.to_deprecated_string(), cookie.path.to_deprecated_string() };
+            CookieStorageKey key { cookie.name.to_byte_string(), cookie.domain.to_byte_string(), cookie.path.to_byte_string() };
 
             if (auto it = storage.find(key); it != storage.end())
                 on_result(cookie, it->value);
diff --git a/Userland/Libraries/LibWebView/CookieJar.h b/Userland/Libraries/LibWebView/CookieJar.h
index 18ac7ac402e..b553dffce2a 100644
--- a/Userland/Libraries/LibWebView/CookieJar.h
+++ b/Userland/Libraries/LibWebView/CookieJar.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/Optional.h>
@@ -22,9 +22,9 @@ namespace WebView {
 struct CookieStorageKey {
     bool operator==(CookieStorageKey const&) const = default;
 
-    DeprecatedString name;
-    DeprecatedString domain;
-    DeprecatedString path;
+    ByteString name;
+    ByteString domain;
+    ByteString path;
 };
 
 class CookieJar {
@@ -48,30 +48,30 @@ public:
     static ErrorOr<CookieJar> create(Database&);
     static CookieJar create();
 
-    DeprecatedString get_cookie(const URL& url, Web::Cookie::Source source);
+    ByteString get_cookie(const URL& url, Web::Cookie::Source source);
     void set_cookie(const URL& url, Web::Cookie::ParsedCookie const& parsed_cookie, Web::Cookie::Source source);
     void update_cookie(Web::Cookie::Cookie);
     void dump_cookies();
     Vector<Web::Cookie::Cookie> get_all_cookies();
     Vector<Web::Cookie::Cookie> get_all_cookies(URL const& url);
-    Optional<Web::Cookie::Cookie> get_named_cookie(URL const& url, DeprecatedString const& name);
+    Optional<Web::Cookie::Cookie> get_named_cookie(URL const& url, ByteString const& name);
 
 private:
     explicit CookieJar(PersistedStorage);
     explicit CookieJar(TransientStorage);
 
-    static Optional<DeprecatedString> canonicalize_domain(const URL& url);
-    static bool domain_matches(DeprecatedString const& string, DeprecatedString const& domain_string);
-    static bool path_matches(DeprecatedString const& request_path, DeprecatedString const& cookie_path);
-    static DeprecatedString default_path(const URL& url);
+    static Optional<ByteString> canonicalize_domain(const URL& url);
+    static bool domain_matches(ByteString const& string, ByteString const& domain_string);
+    static bool path_matches(ByteString const& request_path, ByteString const& cookie_path);
+    static ByteString default_path(const URL& url);
 
     enum class MatchingCookiesSpecMode {
         RFC6265,
         WebDriver,
     };
 
-    void store_cookie(Web::Cookie::ParsedCookie const& parsed_cookie, const URL& url, DeprecatedString canonicalized_domain, Web::Cookie::Source source);
-    Vector<Web::Cookie::Cookie> get_matching_cookies(const URL& url, DeprecatedString const& canonicalized_domain, Web::Cookie::Source source, MatchingCookiesSpecMode mode = MatchingCookiesSpecMode::RFC6265);
+    void store_cookie(Web::Cookie::ParsedCookie const& parsed_cookie, const URL& url, ByteString canonicalized_domain, Web::Cookie::Source source);
+    Vector<Web::Cookie::Cookie> get_matching_cookies(const URL& url, ByteString const& canonicalized_domain, Web::Cookie::Source source, MatchingCookiesSpecMode mode = MatchingCookiesSpecMode::RFC6265);
 
     void insert_cookie_into_database(Web::Cookie::Cookie const& cookie);
     void update_cookie_in_database(Web::Cookie::Cookie const& cookie);
diff --git a/Userland/Libraries/LibWebView/History.cpp b/Userland/Libraries/LibWebView/History.cpp
index 04cb4f75982..1d82794ff3f 100644
--- a/Userland/Libraries/LibWebView/History.cpp
+++ b/Userland/Libraries/LibWebView/History.cpp
@@ -23,7 +23,7 @@ Vector<History::URLTitlePair> History::get_all_history_entries()
     return m_items;
 }
 
-void History::push(const URL& url, DeprecatedString const& title)
+void History::push(const URL& url, ByteString const& title)
 {
     if (!m_items.is_empty() && m_items[m_current].url == url)
         return;
@@ -35,7 +35,7 @@ void History::push(const URL& url, DeprecatedString const& title)
     m_current++;
 }
 
-void History::replace_current(const URL& url, DeprecatedString const& title)
+void History::replace_current(const URL& url, ByteString const& title)
 {
     if (m_current == -1)
         return;
@@ -70,7 +70,7 @@ void History::clear()
     m_current = -1;
 }
 
-void History::update_title(DeprecatedString const& title)
+void History::update_title(ByteString const& title)
 {
     if (m_current == -1)
         return;
diff --git a/Userland/Libraries/LibWebView/History.h b/Userland/Libraries/LibWebView/History.h
index c6599065213..817e4c74d1f 100644
--- a/Userland/Libraries/LibWebView/History.h
+++ b/Userland/Libraries/LibWebView/History.h
@@ -15,14 +15,14 @@ class History {
 public:
     struct URLTitlePair {
         URL url;
-        DeprecatedString title;
+        ByteString title;
     };
     void dump() const;
     Vector<URLTitlePair> get_all_history_entries();
 
-    void push(const URL& url, DeprecatedString const& title);
-    void replace_current(const URL& url, DeprecatedString const& title);
-    void update_title(DeprecatedString const& title);
+    void push(const URL& url, ByteString const& title);
+    void replace_current(const URL& url, ByteString const& title);
+    void update_title(ByteString const& title);
     URLTitlePair current() const;
 
     Vector<StringView> const get_back_title_history();
diff --git a/Userland/Libraries/LibWebView/InspectorClient.cpp b/Userland/Libraries/LibWebView/InspectorClient.cpp
index af4d03d11c3..5c4918a5562 100644
--- a/Userland/Libraries/LibWebView/InspectorClient.cpp
+++ b/Userland/Libraries/LibWebView/InspectorClient.cpp
@@ -158,7 +158,7 @@ InspectorClient::InspectorClient(ViewImplementation& content_web_view, ViewImple
     m_inspector_web_view.on_inspector_executed_console_script = [this](auto const& script) {
         append_console_source(script);
 
-        m_content_web_view.js_console_input(script.to_deprecated_string());
+        m_content_web_view.js_console_input(script.to_byte_string());
     };
 
     load_inspector();
@@ -442,7 +442,7 @@ template<typename Generator>
 static void generate_tree(StringBuilder& builder, JsonObject const& node, Generator&& generator)
 {
     if (auto children = node.get_array("children"sv); children.has_value() && !children->is_empty()) {
-        auto name = node.get_deprecated_string("name"sv).value_or({});
+        auto name = node.get_byte_string("name"sv).value_or({});
         builder.append("<details>"sv);
 
         builder.append("<summary>"sv);
@@ -466,8 +466,8 @@ String InspectorClient::generate_dom_tree(JsonObject const& dom_tree)
     StringBuilder builder;
 
     generate_tree(builder, dom_tree, [&](JsonObject const& node) {
-        auto type = node.get_deprecated_string("type"sv).value_or("unknown"sv);
-        auto name = node.get_deprecated_string("name"sv).value_or({});
+        auto type = node.get_byte_string("type"sv).value_or("unknown"sv);
+        auto name = node.get_byte_string("name"sv).value_or({});
 
         StringBuilder data_attributes;
         auto append_data_attribute = [&](auto name, auto value) {
@@ -484,7 +484,7 @@ String InspectorClient::generate_dom_tree(JsonObject const& dom_tree)
         }
 
         if (type == "text"sv) {
-            auto deprecated_text = node.get_deprecated_string("text"sv).release_value();
+            auto deprecated_text = node.get_byte_string("text"sv).release_value();
             deprecated_text = escape_html_entities(deprecated_text);
 
             auto text = MUST(Web::Infra::strip_and_collapse_whitespace(deprecated_text));
@@ -500,7 +500,7 @@ String InspectorClient::generate_dom_tree(JsonObject const& dom_tree)
         }
 
         if (type == "comment"sv) {
-            auto comment = node.get_deprecated_string("data"sv).release_value();
+            auto comment = node.get_byte_string("data"sv).release_value();
             comment = escape_html_entities(comment);
 
             builder.appendff("<span class=\"hoverable comment\" {}>", data_attributes.string_view());
@@ -512,7 +512,7 @@ String InspectorClient::generate_dom_tree(JsonObject const& dom_tree)
         }
 
         if (type == "shadow-root"sv) {
-            auto mode = node.get_deprecated_string("mode"sv).release_value();
+            auto mode = node.get_byte_string("mode"sv).release_value();
 
             builder.appendff("<span class=\"hoverable internal\" {}>", data_attributes.string_view());
             builder.appendff("{} ({})", name, mode);
@@ -559,11 +559,11 @@ String InspectorClient::generate_accessibility_tree(JsonObject const& accessibil
     StringBuilder builder;
 
     generate_tree(builder, accessibility_tree, [&](JsonObject const& node) {
-        auto type = node.get_deprecated_string("type"sv).value_or("unknown"sv);
-        auto role = node.get_deprecated_string("role"sv).value_or({});
+        auto type = node.get_byte_string("type"sv).value_or("unknown"sv);
+        auto role = node.get_byte_string("role"sv).value_or({});
 
         if (type == "text"sv) {
-            auto text = node.get_deprecated_string("text"sv).release_value();
+            auto text = node.get_byte_string("text"sv).release_value();
             text = escape_html_entities(text);
 
             builder.appendff("<span class=\"hoverable\">");
@@ -579,8 +579,8 @@ String InspectorClient::generate_accessibility_tree(JsonObject const& accessibil
             return;
         }
 
-        auto name = node.get_deprecated_string("name"sv).value_or({});
-        auto description = node.get_deprecated_string("description"sv).value_or({});
+        auto name = node.get_byte_string("name"sv).value_or({});
+        auto description = node.get_byte_string("description"sv).value_or({});
 
         builder.appendff("<span class=\"hoverable\">");
         builder.append(role.to_lowercase());
@@ -616,7 +616,7 @@ void InspectorClient::handle_console_message(i32 message_index)
         request_console_messages();
 }
 
-void InspectorClient::handle_console_messages(i32 start_index, ReadonlySpan<DeprecatedString> message_types, ReadonlySpan<DeprecatedString> messages)
+void InspectorClient::handle_console_messages(i32 start_index, ReadonlySpan<ByteString> message_types, ReadonlySpan<ByteString> messages)
 {
     auto end_index = start_index + static_cast<i32>(message_types.size()) - 1;
     if (end_index <= m_highest_received_message_index) {
diff --git a/Userland/Libraries/LibWebView/InspectorClient.h b/Userland/Libraries/LibWebView/InspectorClient.h
index 8dc4192d2ee..90a0f97320b 100644
--- a/Userland/Libraries/LibWebView/InspectorClient.h
+++ b/Userland/Libraries/LibWebView/InspectorClient.h
@@ -50,7 +50,7 @@ private:
 
     void request_console_messages();
     void handle_console_message(i32 message_index);
-    void handle_console_messages(i32 start_index, ReadonlySpan<DeprecatedString> message_types, ReadonlySpan<DeprecatedString> messages);
+    void handle_console_messages(i32 start_index, ReadonlySpan<ByteString> message_types, ReadonlySpan<ByteString> messages);
 
     void append_console_source(StringView);
     void append_console_message(StringView);
diff --git a/Userland/Libraries/LibWebView/OutOfProcessWebView.cpp b/Userland/Libraries/LibWebView/OutOfProcessWebView.cpp
index 18e6b3a120c..96f2b5f0284 100644
--- a/Userland/Libraries/LibWebView/OutOfProcessWebView.cpp
+++ b/Userland/Libraries/LibWebView/OutOfProcessWebView.cpp
@@ -6,7 +6,7 @@
 
 #include "OutOfProcessWebView.h"
 #include "WebContentClient.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibFileSystemAccessClient/Client.h>
 #include <LibGUI/Application.h>
 #include <LibGUI/Desktop.h>
@@ -65,7 +65,7 @@ OutOfProcessWebView::OutOfProcessWebView()
     };
 
     on_enter_tooltip_area = [](auto, auto tooltip) {
-        GUI::Application::the()->show_tooltip(MUST(String::from_deprecated_string(tooltip)), nullptr);
+        GUI::Application::the()->show_tooltip(MUST(String::from_byte_string(tooltip)), nullptr);
     };
 
     on_leave_tooltip_area = []() {
@@ -228,7 +228,7 @@ void OutOfProcessWebView::did_scroll()
     request_repaint();
 }
 
-DeprecatedString OutOfProcessWebView::dump_layout_tree()
+ByteString OutOfProcessWebView::dump_layout_tree()
 {
     return client().dump_layout_tree();
 }
@@ -258,12 +258,12 @@ void OutOfProcessWebView::set_autoplay_allowlist(Vector<String> allowlist)
     client().async_set_autoplay_allowlist(move(allowlist));
 }
 
-void OutOfProcessWebView::set_proxy_mappings(Vector<DeprecatedString> proxies, HashMap<DeprecatedString, size_t> mappings)
+void OutOfProcessWebView::set_proxy_mappings(Vector<ByteString> proxies, HashMap<ByteString, size_t> mappings)
 {
     client().async_set_proxy_mappings(move(proxies), move(mappings));
 }
 
-void OutOfProcessWebView::connect_to_webdriver(DeprecatedString const& webdriver_ipc_path)
+void OutOfProcessWebView::connect_to_webdriver(ByteString const& webdriver_ipc_path)
 {
     client().async_connect_to_webdriver(webdriver_ipc_path);
 }
diff --git a/Userland/Libraries/LibWebView/OutOfProcessWebView.h b/Userland/Libraries/LibWebView/OutOfProcessWebView.h
index f34673a3045..4ec2224d1f9 100644
--- a/Userland/Libraries/LibWebView/OutOfProcessWebView.h
+++ b/Userland/Libraries/LibWebView/OutOfProcessWebView.h
@@ -34,7 +34,7 @@ class OutOfProcessWebView final
 public:
     virtual ~OutOfProcessWebView() override;
 
-    DeprecatedString dump_layout_tree();
+    ByteString dump_layout_tree();
 
     OrderedHashMap<String, String> get_local_storage_entries();
     OrderedHashMap<String, String> get_session_storage_entries();
@@ -42,8 +42,8 @@ public:
     void set_content_filters(Vector<String>);
     void set_autoplay_allowed_on_all_websites();
     void set_autoplay_allowlist(Vector<String>);
-    void set_proxy_mappings(Vector<DeprecatedString> proxies, HashMap<DeprecatedString, size_t> mappings);
-    void connect_to_webdriver(DeprecatedString const& webdriver_ipc_path);
+    void set_proxy_mappings(Vector<ByteString> proxies, HashMap<ByteString, size_t> mappings);
+    void connect_to_webdriver(ByteString const& webdriver_ipc_path);
 
     void set_window_position(Gfx::IntPoint);
     void set_window_size(Gfx::IntSize);
diff --git a/Userland/Libraries/LibWebView/RequestServerAdapter.cpp b/Userland/Libraries/LibWebView/RequestServerAdapter.cpp
index c09899a081e..bb2e01b84e8 100644
--- a/Userland/Libraries/LibWebView/RequestServerAdapter.cpp
+++ b/Userland/Libraries/LibWebView/RequestServerAdapter.cpp
@@ -86,7 +86,7 @@ RequestServerAdapter::RequestServerAdapter(NonnullRefPtr<Protocol::RequestClient
 
 RequestServerAdapter::~RequestServerAdapter() = default;
 
-RefPtr<Web::ResourceLoaderConnectorRequest> RequestServerAdapter::start_request(DeprecatedString const& method, URL const& url, HashMap<DeprecatedString, DeprecatedString> const& headers, ReadonlyBytes body, Core::ProxyData const& proxy)
+RefPtr<Web::ResourceLoaderConnectorRequest> RequestServerAdapter::start_request(ByteString const& method, URL const& url, HashMap<ByteString, ByteString> const& headers, ReadonlyBytes body, Core::ProxyData const& proxy)
 {
     auto protocol_request = m_protocol_client->start_request(method, url, headers, body, proxy);
     if (!protocol_request)
diff --git a/Userland/Libraries/LibWebView/RequestServerAdapter.h b/Userland/Libraries/LibWebView/RequestServerAdapter.h
index d5634e60595..13f13a62a45 100644
--- a/Userland/Libraries/LibWebView/RequestServerAdapter.h
+++ b/Userland/Libraries/LibWebView/RequestServerAdapter.h
@@ -45,7 +45,7 @@ public:
     virtual void prefetch_dns(AK::URL const& url) override;
     virtual void preconnect(AK::URL const& url) override;
 
-    virtual RefPtr<Web::ResourceLoaderConnectorRequest> start_request(DeprecatedString const& method, URL const&, HashMap<DeprecatedString, DeprecatedString> const& request_headers = {}, ReadonlyBytes request_body = {}, Core::ProxyData const& = {}) override;
+    virtual RefPtr<Web::ResourceLoaderConnectorRequest> start_request(ByteString const& method, URL const&, HashMap<ByteString, ByteString> const& request_headers = {}, ReadonlyBytes request_body = {}, Core::ProxyData const& = {}) override;
 
 private:
     RefPtr<Protocol::RequestClient> m_protocol_client;
diff --git a/Userland/Libraries/LibWebView/URL.cpp b/Userland/Libraries/LibWebView/URL.cpp
index 74df088819d..17451ba98bf 100644
--- a/Userland/Libraries/LibWebView/URL.cpp
+++ b/Userland/Libraries/LibWebView/URL.cpp
@@ -24,7 +24,7 @@ static Optional<URL> create_url_with_url_or_path(String const& url_or_path)
     if (!url.is_error() && url.value().is_valid())
         return url.release_value();
 
-    auto path = LexicalPath::canonicalized_path(url_or_path.to_deprecated_string());
+    auto path = LexicalPath::canonicalized_path(url_or_path.to_byte_string());
     auto url_from_path = URL::create_with_file_scheme(path);
     if (url_from_path.is_valid())
         return url_from_path;
@@ -88,7 +88,7 @@ Optional<URL> sanitize_url(StringView url, Optional<StringView> search_engine, A
         if (path.is_error())
             return {};
 
-        return URL::create_with_file_scheme(path.value().to_deprecated_string());
+        return URL::create_with_file_scheme(path.value().to_byte_string());
     }
 
     auto format_search_engine = [&]() -> Optional<URL> {
diff --git a/Userland/Libraries/LibWebView/ViewImplementation.cpp b/Userland/Libraries/LibWebView/ViewImplementation.cpp
index 9d6012966a4..007ff891a59 100644
--- a/Userland/Libraries/LibWebView/ViewImplementation.cpp
+++ b/Userland/Libraries/LibWebView/ViewImplementation.cpp
@@ -123,7 +123,7 @@ void ViewImplementation::set_preferred_color_scheme(Web::CSS::PreferredColorSche
     client().async_set_preferred_color_scheme(color_scheme);
 }
 
-DeprecatedString ViewImplementation::selected_text()
+ByteString ViewImplementation::selected_text()
 {
     return client().get_selected_text();
 }
@@ -162,11 +162,11 @@ ErrorOr<ViewImplementation::DOMNodeProperties> ViewImplementation::inspect_dom_n
     if (!response.has_style())
         return Error::from_string_view("Inspected node returned no style"sv);
     return DOMNodeProperties {
-        .computed_style_json = TRY(String::from_deprecated_string(response.take_computed_style())),
-        .resolved_style_json = TRY(String::from_deprecated_string(response.take_resolved_style())),
-        .custom_properties_json = TRY(String::from_deprecated_string(response.take_custom_properties())),
-        .node_box_sizing_json = TRY(String::from_deprecated_string(response.take_node_box_sizing())),
-        .aria_properties_state_json = TRY(String::from_deprecated_string(response.take_aria_properties_state())),
+        .computed_style_json = TRY(String::from_byte_string(response.take_computed_style())),
+        .resolved_style_json = TRY(String::from_byte_string(response.take_resolved_style())),
+        .custom_properties_json = TRY(String::from_byte_string(response.take_custom_properties())),
+        .node_box_sizing_json = TRY(String::from_byte_string(response.take_node_box_sizing())),
+        .aria_properties_state_json = TRY(String::from_byte_string(response.take_aria_properties_state())),
     };
 }
 
@@ -225,7 +225,7 @@ Optional<String> ViewImplementation::get_dom_node_html(i32 node_id)
     return client().get_dom_node_html(node_id);
 }
 
-void ViewImplementation::debug_request(DeprecatedString const& request, DeprecatedString const& argument)
+void ViewImplementation::debug_request(ByteString const& request, ByteString const& argument)
 {
     client().async_debug_request(request, argument);
 }
@@ -235,7 +235,7 @@ void ViewImplementation::run_javascript(StringView js_source)
     client().async_run_javascript(js_source);
 }
 
-void ViewImplementation::js_console_input(DeprecatedString const& js_source)
+void ViewImplementation::js_console_input(ByteString const& js_source)
 {
     client().async_js_console_input(js_source);
 }
@@ -380,17 +380,17 @@ void ViewImplementation::handle_web_content_process_crash()
     handle_resize();
     StringBuilder builder;
     builder.append("<html><head><title>Crashed: "sv);
-    builder.append(escape_html_entities(m_url.to_deprecated_string()));
+    builder.append(escape_html_entities(m_url.to_byte_string()));
     builder.append("</title></head><body>"sv);
     builder.append("<h1>Web page crashed"sv);
     if (!m_url.host().has<Empty>()) {
         builder.appendff(" on {}", escape_html_entities(m_url.serialized_host().release_value_but_fixme_should_propagate_errors()));
     }
     builder.append("</h1>"sv);
-    auto escaped_url = escape_html_entities(m_url.to_deprecated_string());
+    auto escaped_url = escape_html_entities(m_url.to_byte_string());
     builder.appendff("The web page <a href=\"{}\">{}</a> has crashed.<br><br>You can reload the page to try again.", escaped_url, escaped_url);
     builder.append("</body></html>"sv);
-    load_html(builder.to_deprecated_string());
+    load_html(builder.to_byte_string());
 }
 
 static ErrorOr<LexicalPath> save_screenshot(Gfx::ShareableBitmap const& bitmap)
diff --git a/Userland/Libraries/LibWebView/ViewImplementation.h b/Userland/Libraries/LibWebView/ViewImplementation.h
index c525430c792..d9c4c343df9 100644
--- a/Userland/Libraries/LibWebView/ViewImplementation.h
+++ b/Userland/Libraries/LibWebView/ViewImplementation.h
@@ -54,7 +54,7 @@ public:
 
     void set_preferred_color_scheme(Web::CSS::PreferredColorScheme);
 
-    DeprecatedString selected_text();
+    ByteString selected_text();
     Optional<String> selected_text_with_whitespace_collapsed();
     void select_all();
 
@@ -76,10 +76,10 @@ public:
     void remove_dom_node(i32 node_id);
     Optional<String> get_dom_node_html(i32 node_id);
 
-    void debug_request(DeprecatedString const& request, DeprecatedString const& argument = {});
+    void debug_request(ByteString const& request, ByteString const& argument = {});
 
     void run_javascript(StringView);
-    void js_console_input(DeprecatedString const& js_source);
+    void js_console_input(ByteString const& js_source);
     void js_console_request_messages(i32 start_index);
 
     void alert_closed();
@@ -120,12 +120,12 @@ public:
     Function<void(Gfx::IntPoint screen_position, Web::Page::MediaContextMenu const&)> on_media_context_menu_request;
     Function<void(const AK::URL&)> on_link_hover;
     Function<void()> on_link_unhover;
-    Function<void(const AK::URL&, DeprecatedString const& target, unsigned modifiers)> on_link_click;
-    Function<void(const AK::URL&, DeprecatedString const& target, unsigned modifiers)> on_link_middle_click;
-    Function<void(DeprecatedString const&)> on_title_change;
+    Function<void(const AK::URL&, ByteString const& target, unsigned modifiers)> on_link_click;
+    Function<void(const AK::URL&, ByteString const& target, unsigned modifiers)> on_link_middle_click;
+    Function<void(ByteString const&)> on_title_change;
     Function<void(const AK::URL&, bool)> on_load_start;
     Function<void(const AK::URL&)> on_load_finish;
-    Function<void(DeprecatedString const& path, i32)> on_request_file;
+    Function<void(ByteString const& path, i32)> on_request_file;
     Function<void()> on_navigate_back;
     Function<void()> on_navigate_forward;
     Function<void()> on_refresh;
@@ -134,7 +134,7 @@ public:
     Function<void(Gfx::IntPoint)> on_scroll_to_point;
     Function<void(Gfx::IntRect)> on_scroll_into_view;
     Function<void(Gfx::StandardCursor)> on_cursor_change;
-    Function<void(Gfx::IntPoint, DeprecatedString const&)> on_enter_tooltip_area;
+    Function<void(Gfx::IntPoint, ByteString const&)> on_enter_tooltip_area;
     Function<void()> on_leave_tooltip_area;
     Function<void(String const& message)> on_request_alert;
     Function<void(String const& message)> on_request_confirm;
@@ -142,14 +142,14 @@ public:
     Function<void(String const& message)> on_request_set_prompt_text;
     Function<void()> on_request_accept_dialog;
     Function<void()> on_request_dismiss_dialog;
-    Function<void(const AK::URL&, DeprecatedString const&)> on_received_source;
-    Function<void(DeprecatedString const&)> on_received_dom_tree;
-    Function<void(DeprecatedString const&)> on_received_accessibility_tree;
+    Function<void(const AK::URL&, ByteString const&)> on_received_source;
+    Function<void(ByteString const&)> on_received_dom_tree;
+    Function<void(ByteString const&)> on_received_accessibility_tree;
     Function<void(i32 message_id)> on_received_console_message;
-    Function<void(i32 start_index, Vector<DeprecatedString> const& message_types, Vector<DeprecatedString> const& messages)> on_received_console_messages;
+    Function<void(i32 start_index, Vector<ByteString> const& message_types, Vector<ByteString> const& messages)> on_received_console_messages;
     Function<Vector<Web::Cookie::Cookie>(AK::URL const& url)> on_get_all_cookies;
-    Function<Optional<Web::Cookie::Cookie>(AK::URL const& url, DeprecatedString const& name)> on_get_named_cookie;
-    Function<DeprecatedString(const AK::URL& url, Web::Cookie::Source source)> on_get_cookie;
+    Function<Optional<Web::Cookie::Cookie>(AK::URL const& url, ByteString const& name)> on_get_named_cookie;
+    Function<ByteString(const AK::URL& url, Web::Cookie::Source source)> on_get_cookie;
     Function<void(const AK::URL& url, Web::Cookie::ParsedCookie const& cookie, Web::Cookie::Source source)> on_set_cookie;
     Function<void(Web::Cookie::Cookie const& cookie)> on_update_cookie;
     Function<void(i32 count_waiting)> on_resource_status_change;
diff --git a/Userland/Libraries/LibWebView/WebContentClient.cpp b/Userland/Libraries/LibWebView/WebContentClient.cpp
index 679bf0865bf..51d77c0e696 100644
--- a/Userland/Libraries/LibWebView/WebContentClient.cpp
+++ b/Userland/Libraries/LibWebView/WebContentClient.cpp
@@ -100,7 +100,7 @@ void WebContentClient::did_layout(Gfx::IntSize content_size)
         m_view.on_did_layout(content_size);
 }
 
-void WebContentClient::did_change_title(DeprecatedString const& title)
+void WebContentClient::did_change_title(ByteString const& title)
 {
     dbgln_if(SPAM_DEBUG, "handle: WebContentClient::DidChangeTitle! title={}", title);
 
@@ -108,7 +108,7 @@ void WebContentClient::did_change_title(DeprecatedString const& title)
         return;
 
     if (title.is_empty())
-        m_view.on_title_change(m_view.url().to_deprecated_string());
+        m_view.on_title_change(m_view.url().to_byte_string());
     else
         m_view.on_title_change(title);
 }
@@ -132,7 +132,7 @@ void WebContentClient::did_request_scroll_into_view(Gfx::IntRect const& rect)
         m_view.on_scroll_into_view(rect);
 }
 
-void WebContentClient::did_enter_tooltip_area(Gfx::IntPoint content_position, DeprecatedString const& title)
+void WebContentClient::did_enter_tooltip_area(Gfx::IntPoint content_position, ByteString const& title)
 {
     if (m_view.on_enter_tooltip_area)
         m_view.on_enter_tooltip_area(m_view.to_widget_position(content_position), title);
@@ -160,13 +160,13 @@ void WebContentClient::did_unhover_link()
         m_view.on_link_unhover();
 }
 
-void WebContentClient::did_click_link(AK::URL const& url, DeprecatedString const& target, unsigned modifiers)
+void WebContentClient::did_click_link(AK::URL const& url, ByteString const& target, unsigned modifiers)
 {
     if (m_view.on_link_click)
         m_view.on_link_click(url, target, modifiers);
 }
 
-void WebContentClient::did_middle_click_link(AK::URL const& url, DeprecatedString const& target, unsigned modifiers)
+void WebContentClient::did_middle_click_link(AK::URL const& url, ByteString const& target, unsigned modifiers)
 {
     if (m_view.on_link_middle_click)
         m_view.on_link_middle_click(url, target, modifiers);
@@ -178,37 +178,37 @@ void WebContentClient::did_request_context_menu(Gfx::IntPoint content_position)
         m_view.on_context_menu_request(m_view.to_widget_position(content_position));
 }
 
-void WebContentClient::did_request_link_context_menu(Gfx::IntPoint content_position, AK::URL const& url, DeprecatedString const&, unsigned)
+void WebContentClient::did_request_link_context_menu(Gfx::IntPoint content_position, AK::URL const& url, ByteString const&, unsigned)
 {
     if (m_view.on_link_context_menu_request)
         m_view.on_link_context_menu_request(url, m_view.to_widget_position(content_position));
 }
 
-void WebContentClient::did_request_image_context_menu(Gfx::IntPoint content_position, AK::URL const& url, DeprecatedString const&, unsigned, Gfx::ShareableBitmap const& bitmap)
+void WebContentClient::did_request_image_context_menu(Gfx::IntPoint content_position, AK::URL const& url, ByteString const&, unsigned, Gfx::ShareableBitmap const& bitmap)
 {
     if (m_view.on_image_context_menu_request)
         m_view.on_image_context_menu_request(url, m_view.to_widget_position(content_position), bitmap);
 }
 
-void WebContentClient::did_request_media_context_menu(Gfx::IntPoint content_position, DeprecatedString const&, unsigned, Web::Page::MediaContextMenu const& menu)
+void WebContentClient::did_request_media_context_menu(Gfx::IntPoint content_position, ByteString const&, unsigned, Web::Page::MediaContextMenu const& menu)
 {
     if (m_view.on_media_context_menu_request)
         m_view.on_media_context_menu_request(m_view.to_widget_position(content_position), menu);
 }
 
-void WebContentClient::did_get_source(AK::URL const& url, DeprecatedString const& source)
+void WebContentClient::did_get_source(AK::URL const& url, ByteString const& source)
 {
     if (m_view.on_received_source)
         m_view.on_received_source(url, source);
 }
 
-void WebContentClient::did_get_dom_tree(DeprecatedString const& dom_tree)
+void WebContentClient::did_get_dom_tree(ByteString const& dom_tree)
 {
     if (m_view.on_received_dom_tree)
         m_view.on_received_dom_tree(dom_tree);
 }
 
-void WebContentClient::did_get_accessibility_tree(DeprecatedString const& accessibility_tree)
+void WebContentClient::did_get_accessibility_tree(ByteString const& accessibility_tree)
 {
     if (m_view.on_received_accessibility_tree)
         m_view.on_received_accessibility_tree(accessibility_tree);
@@ -220,7 +220,7 @@ void WebContentClient::did_output_js_console_message(i32 message_index)
         m_view.on_received_console_message(message_index);
 }
 
-void WebContentClient::did_get_js_console_messages(i32 start_index, Vector<DeprecatedString> const& message_types, Vector<DeprecatedString> const& messages)
+void WebContentClient::did_get_js_console_messages(i32 start_index, Vector<ByteString> const& message_types, Vector<ByteString> const& messages)
 {
     if (m_view.on_received_console_messages)
         m_view.on_received_console_messages(start_index, message_types, messages);
@@ -280,7 +280,7 @@ Messages::WebContentClient::DidRequestAllCookiesResponse WebContentClient::did_r
     return Vector<Web::Cookie::Cookie> {};
 }
 
-Messages::WebContentClient::DidRequestNamedCookieResponse WebContentClient::did_request_named_cookie(AK::URL const& url, DeprecatedString const& name)
+Messages::WebContentClient::DidRequestNamedCookieResponse WebContentClient::did_request_named_cookie(AK::URL const& url, ByteString const& name)
 {
     if (m_view.on_get_named_cookie)
         return m_view.on_get_named_cookie(url, name);
@@ -291,7 +291,7 @@ Messages::WebContentClient::DidRequestCookieResponse WebContentClient::did_reque
 {
     if (m_view.on_get_cookie)
         return m_view.on_get_cookie(url, static_cast<Web::Cookie::Source>(source));
-    return DeprecatedString {};
+    return ByteString {};
 }
 
 void WebContentClient::did_set_cookie(AK::URL const& url, Web::Cookie::ParsedCookie const& cookie, u8 source)
@@ -372,7 +372,7 @@ Messages::WebContentClient::DidRequestFullscreenWindowResponse WebContentClient:
     return Gfx::IntRect {};
 }
 
-void WebContentClient::did_request_file(DeprecatedString const& path, i32 request_id)
+void WebContentClient::did_request_file(ByteString const& path, i32 request_id)
 {
     if (m_view.on_request_file)
         m_view.on_request_file(path, request_id);
diff --git a/Userland/Libraries/LibWebView/WebContentClient.h b/Userland/Libraries/LibWebView/WebContentClient.h
index 8e611de0878..a1a281db42a 100644
--- a/Userland/Libraries/LibWebView/WebContentClient.h
+++ b/Userland/Libraries/LibWebView/WebContentClient.h
@@ -39,26 +39,26 @@ private:
     virtual void did_change_selection() override;
     virtual void did_request_cursor_change(i32) override;
     virtual void did_layout(Gfx::IntSize) override;
-    virtual void did_change_title(DeprecatedString const&) override;
+    virtual void did_change_title(ByteString const&) override;
     virtual void did_request_scroll(i32, i32) override;
     virtual void did_request_scroll_to(Gfx::IntPoint) override;
     virtual void did_request_scroll_into_view(Gfx::IntRect const&) override;
-    virtual void did_enter_tooltip_area(Gfx::IntPoint, DeprecatedString const&) override;
+    virtual void did_enter_tooltip_area(Gfx::IntPoint, ByteString const&) override;
     virtual void did_leave_tooltip_area() override;
     virtual void did_hover_link(AK::URL const&) override;
     virtual void did_unhover_link() override;
-    virtual void did_click_link(AK::URL const&, DeprecatedString const&, unsigned) override;
-    virtual void did_middle_click_link(AK::URL const&, DeprecatedString const&, unsigned) override;
+    virtual void did_click_link(AK::URL const&, ByteString const&, unsigned) override;
+    virtual void did_middle_click_link(AK::URL const&, ByteString const&, unsigned) override;
     virtual void did_start_loading(AK::URL const&, bool) override;
     virtual void did_request_context_menu(Gfx::IntPoint) override;
-    virtual void did_request_link_context_menu(Gfx::IntPoint, AK::URL const&, DeprecatedString const&, unsigned) override;
-    virtual void did_request_image_context_menu(Gfx::IntPoint, AK::URL const&, DeprecatedString const&, unsigned, Gfx::ShareableBitmap const&) override;
-    virtual void did_request_media_context_menu(Gfx::IntPoint, DeprecatedString const&, unsigned, Web::Page::MediaContextMenu const&) override;
-    virtual void did_get_source(AK::URL const&, DeprecatedString const&) override;
-    virtual void did_get_dom_tree(DeprecatedString const&) override;
-    virtual void did_get_accessibility_tree(DeprecatedString const&) override;
+    virtual void did_request_link_context_menu(Gfx::IntPoint, AK::URL const&, ByteString const&, unsigned) override;
+    virtual void did_request_image_context_menu(Gfx::IntPoint, AK::URL const&, ByteString const&, unsigned, Gfx::ShareableBitmap const&) override;
+    virtual void did_request_media_context_menu(Gfx::IntPoint, ByteString const&, unsigned, Web::Page::MediaContextMenu const&) override;
+    virtual void did_get_source(AK::URL const&, ByteString const&) override;
+    virtual void did_get_dom_tree(ByteString const&) override;
+    virtual void did_get_accessibility_tree(ByteString const&) override;
     virtual void did_output_js_console_message(i32 message_index) override;
-    virtual void did_get_js_console_messages(i32 start_index, Vector<DeprecatedString> const& message_types, Vector<DeprecatedString> const& messages) override;
+    virtual void did_get_js_console_messages(i32 start_index, Vector<ByteString> const& message_types, Vector<ByteString> const& messages) override;
     virtual void did_change_favicon(Gfx::ShareableBitmap const&) override;
     virtual void did_request_alert(String const&) override;
     virtual void did_request_confirm(String const&) override;
@@ -67,7 +67,7 @@ private:
     virtual void did_request_accept_dialog() override;
     virtual void did_request_dismiss_dialog() override;
     virtual Messages::WebContentClient::DidRequestAllCookiesResponse did_request_all_cookies(AK::URL const&) override;
-    virtual Messages::WebContentClient::DidRequestNamedCookieResponse did_request_named_cookie(AK::URL const&, DeprecatedString const&) override;
+    virtual Messages::WebContentClient::DidRequestNamedCookieResponse did_request_named_cookie(AK::URL const&, ByteString const&) override;
     virtual Messages::WebContentClient::DidRequestCookieResponse did_request_cookie(AK::URL const&, u8) override;
     virtual void did_set_cookie(AK::URL const&, Web::Cookie::ParsedCookie const&, u8) override;
     virtual void did_update_cookie(Web::Cookie::Cookie const&) override;
@@ -81,7 +81,7 @@ private:
     virtual Messages::WebContentClient::DidRequestMaximizeWindowResponse did_request_maximize_window() override;
     virtual Messages::WebContentClient::DidRequestMinimizeWindowResponse did_request_minimize_window() override;
     virtual Messages::WebContentClient::DidRequestFullscreenWindowResponse did_request_fullscreen_window() override;
-    virtual void did_request_file(DeprecatedString const& path, i32) override;
+    virtual void did_request_file(ByteString const& path, i32) override;
     virtual void did_request_color_picker(Color const& current_color) override;
     virtual void did_request_select_dropdown(Gfx::IntPoint content_position, i32 minimum_width, Vector<Web::HTML::SelectItem> const& items) override;
     virtual void did_finish_handling_input_event(bool event_was_accepted) override;
diff --git a/Userland/Libraries/LibWebView/WebSocketClientAdapter.cpp b/Userland/Libraries/LibWebView/WebSocketClientAdapter.cpp
index 9c61b1ebeee..5248c327221 100644
--- a/Userland/Libraries/LibWebView/WebSocketClientAdapter.cpp
+++ b/Userland/Libraries/LibWebView/WebSocketClientAdapter.cpp
@@ -51,7 +51,7 @@ WebSocketClientSocketAdapter::WebSocketClientSocketAdapter(NonnullRefPtr<Protoco
             }
         }
     };
-    m_websocket->on_close = [weak_this = make_weak_ptr()](u16 code, DeprecatedString reason, bool was_clean) {
+    m_websocket->on_close = [weak_this = make_weak_ptr()](u16 code, ByteString reason, bool was_clean) {
         if (auto strong_this = weak_this.strong_ref())
             if (strong_this->on_close)
                 strong_this->on_close(code, move(reason), was_clean);
@@ -87,7 +87,7 @@ Web::WebSockets::WebSocket::ReadyState WebSocketClientSocketAdapter::ready_state
     VERIFY_NOT_REACHED();
 }
 
-DeprecatedString WebSocketClientSocketAdapter::subprotocol_in_use()
+ByteString WebSocketClientSocketAdapter::subprotocol_in_use()
 {
     return m_websocket->subprotocol_in_use();
 }
@@ -102,7 +102,7 @@ void WebSocketClientSocketAdapter::send(StringView text_message)
     m_websocket->send(text_message);
 }
 
-void WebSocketClientSocketAdapter::close(u16 code, DeprecatedString reason)
+void WebSocketClientSocketAdapter::close(u16 code, ByteString reason)
 {
     m_websocket->close(code, reason);
 }
@@ -125,7 +125,7 @@ WebSocketClientManagerAdapter::WebSocketClientManagerAdapter(NonnullRefPtr<Proto
 
 WebSocketClientManagerAdapter::~WebSocketClientManagerAdapter() = default;
 
-RefPtr<Web::WebSockets::WebSocketClientSocket> WebSocketClientManagerAdapter::connect(const AK::URL& url, DeprecatedString const& origin, Vector<DeprecatedString> const& protocols)
+RefPtr<Web::WebSockets::WebSocketClientSocket> WebSocketClientManagerAdapter::connect(const AK::URL& url, ByteString const& origin, Vector<ByteString> const& protocols)
 {
     auto underlying_websocket = m_websocket_client->connect(url, origin, protocols);
     if (!underlying_websocket)
diff --git a/Userland/Libraries/LibWebView/WebSocketClientAdapter.h b/Userland/Libraries/LibWebView/WebSocketClientAdapter.h
index 5ae5590ff1c..58cc955e5f1 100644
--- a/Userland/Libraries/LibWebView/WebSocketClientAdapter.h
+++ b/Userland/Libraries/LibWebView/WebSocketClientAdapter.h
@@ -26,11 +26,11 @@ public:
     virtual ~WebSocketClientSocketAdapter() override;
 
     virtual Web::WebSockets::WebSocket::ReadyState ready_state() override;
-    virtual DeprecatedString subprotocol_in_use() override;
+    virtual ByteString subprotocol_in_use() override;
 
     virtual void send(ByteBuffer binary_or_text_message, bool is_text) override;
     virtual void send(StringView text_message) override;
-    virtual void close(u16 code = 1005, DeprecatedString reason = {}) override;
+    virtual void close(u16 code = 1005, ByteString reason = {}) override;
 
 private:
     WebSocketClientSocketAdapter(NonnullRefPtr<Protocol::WebSocket>);
@@ -45,7 +45,7 @@ public:
 
     virtual ~WebSocketClientManagerAdapter() override;
 
-    virtual RefPtr<Web::WebSockets::WebSocketClientSocket> connect(const AK::URL&, DeprecatedString const& origin, Vector<DeprecatedString> const& protocols) override;
+    virtual RefPtr<Web::WebSockets::WebSocketClientSocket> connect(const AK::URL&, ByteString const& origin, Vector<ByteString> const& protocols) override;
 
 private:
     WebSocketClientManagerAdapter(NonnullRefPtr<Protocol::WebSocketClient>);
diff --git a/Userland/Libraries/LibX86/ELFSymbolProvider.h b/Userland/Libraries/LibX86/ELFSymbolProvider.h
index 52de1a09ac5..f5c3147aab6 100644
--- a/Userland/Libraries/LibX86/ELFSymbolProvider.h
+++ b/Userland/Libraries/LibX86/ELFSymbolProvider.h
@@ -19,7 +19,7 @@ public:
     {
     }
 
-    virtual DeprecatedString symbolicate(FlatPtr address, u32* offset = nullptr) const override
+    virtual ByteString symbolicate(FlatPtr address, u32* offset = nullptr) const override
     {
         return m_elf.symbolicate(address - m_base_address, offset);
     }
diff --git a/Userland/Libraries/LibX86/Instruction.cpp b/Userland/Libraries/LibX86/Instruction.cpp
index 9daf1430806..6fdda96538d 100644
--- a/Userland/Libraries/LibX86/Instruction.cpp
+++ b/Userland/Libraries/LibX86/Instruction.cpp
@@ -1291,107 +1291,107 @@ StringView Instruction::reg64_name() const
     return register_name(static_cast<RegisterIndex64>(register_index()));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_o8(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_o8(Instruction const& insn) const
 {
     if (is_register())
         return register_name(reg8());
-    return DeprecatedString::formatted("[{}]", to_deprecated_string(insn));
+    return ByteString::formatted("[{}]", to_byte_string(insn));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_o16(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_o16(Instruction const& insn) const
 {
     if (is_register())
         return register_name(reg16());
-    return DeprecatedString::formatted("[{}]", to_deprecated_string(insn));
+    return ByteString::formatted("[{}]", to_byte_string(insn));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_o32(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_o32(Instruction const& insn) const
 {
     if (is_register())
         return register_name(reg32());
-    return DeprecatedString::formatted("[{}]", to_deprecated_string(insn));
+    return ByteString::formatted("[{}]", to_byte_string(insn));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_o64(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_o64(Instruction const& insn) const
 {
     if (is_register())
         return register_name(reg64());
-    return DeprecatedString::formatted("[{}]", to_deprecated_string(insn));
+    return ByteString::formatted("[{}]", to_byte_string(insn));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_fpu_reg() const
+ByteString MemoryOrRegisterReference::to_byte_string_fpu_reg() const
 {
     VERIFY(is_register());
     return register_name(reg_fpu());
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_fpu_mem(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_fpu_mem(Instruction const& insn) const
 {
     VERIFY(!is_register());
-    return DeprecatedString::formatted("[{}]", to_deprecated_string(insn));
+    return ByteString::formatted("[{}]", to_byte_string(insn));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_fpu_ax16() const
+ByteString MemoryOrRegisterReference::to_byte_string_fpu_ax16() const
 {
     VERIFY(is_register());
     return register_name(reg16());
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_fpu16(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_fpu16(Instruction const& insn) const
 {
     if (is_register())
         return register_name(reg_fpu());
-    return DeprecatedString::formatted("word ptr [{}]", to_deprecated_string(insn));
+    return ByteString::formatted("word ptr [{}]", to_byte_string(insn));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_fpu32(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_fpu32(Instruction const& insn) const
 {
     if (is_register())
         return register_name(reg_fpu());
-    return DeprecatedString::formatted("dword ptr [{}]", to_deprecated_string(insn));
+    return ByteString::formatted("dword ptr [{}]", to_byte_string(insn));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_fpu64(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_fpu64(Instruction const& insn) const
 {
     if (is_register())
         return register_name(reg_fpu());
-    return DeprecatedString::formatted("qword ptr [{}]", to_deprecated_string(insn));
+    return ByteString::formatted("qword ptr [{}]", to_byte_string(insn));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_fpu80(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_fpu80(Instruction const& insn) const
 {
     VERIFY(!is_register());
-    return DeprecatedString::formatted("tbyte ptr [{}]", to_deprecated_string(insn));
+    return ByteString::formatted("tbyte ptr [{}]", to_byte_string(insn));
 }
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_mm(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_mm(Instruction const& insn) const
 {
     if (is_register())
         return register_name(static_cast<MMXRegisterIndex>(m_register_index));
-    return DeprecatedString::formatted("[{}]", to_deprecated_string(insn));
+    return ByteString::formatted("[{}]", to_byte_string(insn));
 }
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_xmm(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string_xmm(Instruction const& insn) const
 {
     if (is_register())
         return register_name(static_cast<XMMRegisterIndex>(m_register_index));
-    return DeprecatedString::formatted("[{}]", to_deprecated_string(insn));
+    return ByteString::formatted("[{}]", to_byte_string(insn));
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string(Instruction const& insn) const
+ByteString MemoryOrRegisterReference::to_byte_string(Instruction const& insn) const
 {
     switch (insn.address_size()) {
     case AddressSize::Size64:
-        return to_deprecated_string_a64();
+        return to_byte_string_a64();
     case AddressSize::Size32:
-        return insn.mode() == ProcessorMode::Long ? to_deprecated_string_a64() : to_deprecated_string_a32();
+        return insn.mode() == ProcessorMode::Long ? to_byte_string_a64() : to_byte_string_a32();
     case AddressSize::Size16:
-        return to_deprecated_string_a16();
+        return to_byte_string_a16();
     }
     VERIFY_NOT_REACHED();
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a16() const
+ByteString MemoryOrRegisterReference::to_byte_string_a16() const
 {
-    DeprecatedString base;
+    ByteString base;
     bool hasDisplacement = false;
 
     switch (rm()) {
@@ -1418,7 +1418,7 @@ DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a16() const
         break;
     case 6:
         if (mod() == 0)
-            base = DeprecatedString::formatted("{:#04x}", m_displacement16);
+            base = ByteString::formatted("{:#04x}", m_displacement16);
         else
             base = "bp";
         break;
@@ -1433,14 +1433,14 @@ DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a16() const
     if (!hasDisplacement)
         return base;
 
-    return DeprecatedString::formatted("{}{:+#x}", base, (i16)m_displacement16);
+    return ByteString::formatted("{}{:+#x}", base, (i16)m_displacement16);
 }
 
-DeprecatedString MemoryOrRegisterReference::sib_to_deprecated_string(ProcessorMode mode) const
+ByteString MemoryOrRegisterReference::sib_to_byte_string(ProcessorMode mode) const
 {
-    DeprecatedString scale;
-    DeprecatedString index;
-    DeprecatedString base;
+    ByteString scale;
+    ByteString index;
+    ByteString base;
     switch (m_sib_scale) {
     case 0:;
         break;
@@ -1477,10 +1477,10 @@ DeprecatedString MemoryOrRegisterReference::sib_to_deprecated_string(ProcessorMo
         builder.append(index);
         builder.append(scale);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a64() const
+ByteString MemoryOrRegisterReference::to_byte_string_a64() const
 {
     if (is_register())
         return register_name(static_cast<RegisterIndex64>(m_register_index));
@@ -1497,7 +1497,7 @@ DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a64() const
     if (m_has_sib && m_sib_base == 5)
         has_displacement = true;
 
-    DeprecatedString base;
+    ByteString base;
     switch (m_rm) {
     case 5:
         if (mod() == 0)
@@ -1506,7 +1506,7 @@ DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a64() const
             base = "rbp";
         break;
     case 4:
-        base = sib_to_deprecated_string(ProcessorMode::Long);
+        base = sib_to_byte_string(ProcessorMode::Long);
         break;
     default:
         base = register_name(RegisterIndex64(m_rm));
@@ -1515,10 +1515,10 @@ DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a64() const
     if (!has_displacement)
         return base;
 
-    return DeprecatedString::formatted("{}{:+#x}", base, (i32)m_displacement32);
+    return ByteString::formatted("{}{:+#x}", base, (i32)m_displacement32);
 }
 
-DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a32() const
+ByteString MemoryOrRegisterReference::to_byte_string_a32() const
 {
     if (is_register())
         return register_name(static_cast<RegisterIndex32>(m_register_index));
@@ -1532,16 +1532,16 @@ DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a32() const
     if (m_has_sib && m_sib_base == 5)
         has_displacement = true;
 
-    DeprecatedString base;
+    ByteString base;
     switch (m_rm) {
     case 5:
         if (mod() == 0)
-            base = DeprecatedString::formatted("{:x}", m_displacement32);
+            base = ByteString::formatted("{:x}", m_displacement32);
         else
             base = "ebp";
         break;
     case 4:
-        base = sib_to_deprecated_string(ProcessorMode::Protected);
+        base = sib_to_byte_string(ProcessorMode::Protected);
         break;
     default:
         base = register_name(RegisterIndex32(m_rm));
@@ -1550,27 +1550,27 @@ DeprecatedString MemoryOrRegisterReference::to_deprecated_string_a32() const
     if (!has_displacement)
         return base;
 
-    return DeprecatedString::formatted("{}{:+#x}", base, (i32)m_displacement32);
+    return ByteString::formatted("{}{:+#x}", base, (i32)m_displacement32);
 }
 
-static DeprecatedString relative_address(u32 origin, bool x32, i8 imm)
+static ByteString relative_address(u32 origin, bool x32, i8 imm)
 {
     if (x32)
-        return DeprecatedString::formatted("{:x}", origin + imm);
+        return ByteString::formatted("{:x}", origin + imm);
     u16 w = origin & 0xffff;
-    return DeprecatedString::formatted("{:x}", w + imm);
+    return ByteString::formatted("{:x}", w + imm);
 }
 
-static DeprecatedString relative_address(u32 origin, bool x32, i32 imm)
+static ByteString relative_address(u32 origin, bool x32, i32 imm)
 {
     if (x32)
-        return DeprecatedString::formatted("{:x}", origin + imm);
+        return ByteString::formatted("{:x}", origin + imm);
     u16 w = origin & 0xffff;
     i16 si = imm;
-    return DeprecatedString::formatted("{:x}", w + si);
+    return ByteString::formatted("{:x}", w + si);
 }
 
-DeprecatedString Instruction::to_deprecated_string(u32 origin, SymbolProvider const* symbol_provider, bool x32) const
+ByteString Instruction::to_byte_string(u32 origin, SymbolProvider const* symbol_provider, bool x32) const
 {
     StringBuilder builder;
     if (has_segment_prefix())
@@ -1606,18 +1606,18 @@ DeprecatedString Instruction::to_deprecated_string(u32 origin, SymbolProvider co
     // Note: SSE instructions use these to toggle between packed and single data
     if (has_rep_prefix() && !(m_descriptor->format > __SSE && m_descriptor->format < __EndFormatsWithRMByte))
         builder.append(m_rep_prefix == Prefix::REPNZ ? "repnz "sv : "repz "sv);
-    to_deprecated_string_internal(builder, origin, symbol_provider, x32);
-    return builder.to_deprecated_string();
+    to_byte_string_internal(builder, origin, symbol_provider, x32);
+    return builder.to_byte_string();
 }
 
-void Instruction::to_deprecated_string_internal(StringBuilder& builder, u32 origin, SymbolProvider const* symbol_provider, bool x32) const
+void Instruction::to_byte_string_internal(StringBuilder& builder, u32 origin, SymbolProvider const* symbol_provider, bool x32) const
 {
     if (!m_descriptor) {
         builder.appendff("db {:02x}", m_op);
         return;
     }
 
-    DeprecatedString mnemonic = DeprecatedString(m_descriptor->mnemonic).to_lowercase();
+    ByteString mnemonic = ByteString(m_descriptor->mnemonic).to_lowercase();
 
     auto append_mnemonic = [&] { builder.append(mnemonic); };
 
@@ -1636,22 +1636,22 @@ void Instruction::to_deprecated_string_internal(StringBuilder& builder, u32 orig
         }
     };
 
-    auto append_rm8 = [&] { builder.append(m_modrm.to_deprecated_string_o8(*this)); };
-    auto append_rm16 = [&] { builder.append(m_modrm.to_deprecated_string_o16(*this)); };
+    auto append_rm8 = [&] { builder.append(m_modrm.to_byte_string_o8(*this)); };
+    auto append_rm16 = [&] { builder.append(m_modrm.to_byte_string_o16(*this)); };
     auto append_rm32 = [&] {
         if (m_operand_size == OperandSize::Size64)
-            builder.append(m_modrm.to_deprecated_string_o64(*this));
+            builder.append(m_modrm.to_byte_string_o64(*this));
         else
-            builder.append(m_modrm.to_deprecated_string_o32(*this));
+            builder.append(m_modrm.to_byte_string_o32(*this));
     };
-    auto append_rm64 = [&] { builder.append(m_modrm.to_deprecated_string_o64(*this)); };
-    auto append_fpu_reg = [&] { builder.append(m_modrm.to_deprecated_string_fpu_reg()); };
-    auto append_fpu_mem = [&] { builder.append(m_modrm.to_deprecated_string_fpu_mem(*this)); };
-    auto append_fpu_ax16 = [&] { builder.append(m_modrm.to_deprecated_string_fpu_ax16()); };
-    auto append_fpu_rm16 = [&] { builder.append(m_modrm.to_deprecated_string_fpu16(*this)); };
-    auto append_fpu_rm32 = [&] { builder.append(m_modrm.to_deprecated_string_fpu32(*this)); };
-    auto append_fpu_rm64 = [&] { builder.append(m_modrm.to_deprecated_string_fpu64(*this)); };
-    auto append_fpu_rm80 = [&] { builder.append(m_modrm.to_deprecated_string_fpu80(*this)); };
+    auto append_rm64 = [&] { builder.append(m_modrm.to_byte_string_o64(*this)); };
+    auto append_fpu_reg = [&] { builder.append(m_modrm.to_byte_string_fpu_reg()); };
+    auto append_fpu_mem = [&] { builder.append(m_modrm.to_byte_string_fpu_mem(*this)); };
+    auto append_fpu_ax16 = [&] { builder.append(m_modrm.to_byte_string_fpu_ax16()); };
+    auto append_fpu_rm16 = [&] { builder.append(m_modrm.to_byte_string_fpu16(*this)); };
+    auto append_fpu_rm32 = [&] { builder.append(m_modrm.to_byte_string_fpu32(*this)); };
+    auto append_fpu_rm64 = [&] { builder.append(m_modrm.to_byte_string_fpu64(*this)); };
+    auto append_fpu_rm80 = [&] { builder.append(m_modrm.to_byte_string_fpu80(*this)); };
     auto append_imm8 = [&] { builder.appendff("{:#02x}", imm8()); };
     auto append_imm8_2 = [&] { builder.appendff("{:#02x}", imm8_2()); };
     auto append_imm16 = [&] { builder.appendff("{:#04x}", imm16()); };
@@ -1694,12 +1694,12 @@ void Instruction::to_deprecated_string_internal(StringBuilder& builder, u32 orig
     auto append_relative_imm32 = [&] { formatted_address(origin + 5, x32, i32(imm32())); };
 
     auto append_mm = [&] { builder.appendff("mm{}", register_index()); };
-    auto append_mmrm32 = [&] { builder.append(m_modrm.to_deprecated_string_mm(*this)); };
-    auto append_mmrm64 = [&] { builder.append(m_modrm.to_deprecated_string_mm(*this)); };
+    auto append_mmrm32 = [&] { builder.append(m_modrm.to_byte_string_mm(*this)); };
+    auto append_mmrm64 = [&] { builder.append(m_modrm.to_byte_string_mm(*this)); };
     auto append_xmm = [&] { builder.appendff("xmm{}", register_index()); };
-    auto append_xmmrm32 = [&] { builder.append(m_modrm.to_deprecated_string_xmm(*this)); };
-    auto append_xmmrm64 = [&] { builder.append(m_modrm.to_deprecated_string_xmm(*this)); };
-    auto append_xmmrm128 = [&] { builder.append(m_modrm.to_deprecated_string_xmm(*this)); };
+    auto append_xmmrm32 = [&] { builder.append(m_modrm.to_byte_string_xmm(*this)); };
+    auto append_xmmrm64 = [&] { builder.append(m_modrm.to_byte_string_xmm(*this)); };
+    auto append_xmmrm128 = [&] { builder.append(m_modrm.to_byte_string_xmm(*this)); };
 
     auto append_mm_or_xmm = [&] {
         if (has_operand_size_override_prefix())
@@ -2476,12 +2476,12 @@ void Instruction::to_deprecated_string_internal(StringBuilder& builder, u32 orig
     case MultibyteWithSlash:
     case __BeginFormatsWithRMByte:
     case __EndFormatsWithRMByte:
-        builder.append(DeprecatedString::formatted("(!{})", mnemonic));
+        builder.append(ByteString::formatted("(!{})", mnemonic));
         break;
     }
 }
 
-DeprecatedString Instruction::mnemonic() const
+ByteString Instruction::mnemonic() const
 {
     if (!m_descriptor) {
         VERIFY_NOT_REACHED();
diff --git a/Userland/Libraries/LibX86/Instruction.h b/Userland/Libraries/LibX86/Instruction.h
index 6c932e5988f..ce24bb0074f 100644
--- a/Userland/Libraries/LibX86/Instruction.h
+++ b/Userland/Libraries/LibX86/Instruction.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <AK/StdLibExtras.h>
 #include <AK/Types.h>
@@ -21,7 +21,7 @@ typedef void (Interpreter::*InstructionHandler)(Instruction const&);
 
 class SymbolProvider {
 public:
-    virtual DeprecatedString symbolicate(FlatPtr, u32* offset = nullptr) const = 0;
+    virtual ByteString symbolicate(FlatPtr, u32* offset = nullptr) const = 0;
 
 protected:
     virtual ~SymbolProvider() = default;
@@ -519,20 +519,20 @@ class MemoryOrRegisterReference {
     friend class Instruction;
 
 public:
-    DeprecatedString to_deprecated_string_o8(Instruction const&) const;
-    DeprecatedString to_deprecated_string_o16(Instruction const&) const;
-    DeprecatedString to_deprecated_string_o32(Instruction const&) const;
-    DeprecatedString to_deprecated_string_o64(Instruction const&) const;
-    DeprecatedString to_deprecated_string_fpu_reg() const;
-    DeprecatedString to_deprecated_string_fpu_mem(Instruction const&) const;
-    DeprecatedString to_deprecated_string_fpu_ax16() const;
-    DeprecatedString to_deprecated_string_fpu16(Instruction const&) const;
-    DeprecatedString to_deprecated_string_fpu32(Instruction const&) const;
-    DeprecatedString to_deprecated_string_fpu64(Instruction const&) const;
-    DeprecatedString to_deprecated_string_fpu80(Instruction const&) const;
-    DeprecatedString to_deprecated_string_mm(Instruction const&) const;
-    DeprecatedString to_deprecated_string_xmm(Instruction const&) const;
-    DeprecatedString sib_to_deprecated_string(ProcessorMode) const;
+    ByteString to_byte_string_o8(Instruction const&) const;
+    ByteString to_byte_string_o16(Instruction const&) const;
+    ByteString to_byte_string_o32(Instruction const&) const;
+    ByteString to_byte_string_o64(Instruction const&) const;
+    ByteString to_byte_string_fpu_reg() const;
+    ByteString to_byte_string_fpu_mem(Instruction const&) const;
+    ByteString to_byte_string_fpu_ax16() const;
+    ByteString to_byte_string_fpu16(Instruction const&) const;
+    ByteString to_byte_string_fpu32(Instruction const&) const;
+    ByteString to_byte_string_fpu64(Instruction const&) const;
+    ByteString to_byte_string_fpu80(Instruction const&) const;
+    ByteString to_byte_string_mm(Instruction const&) const;
+    ByteString to_byte_string_xmm(Instruction const&) const;
+    ByteString sib_to_byte_string(ProcessorMode) const;
 
     bool is_register() const { return m_register_index != 0x7f; }
 
@@ -581,10 +581,10 @@ public:
 private:
     MemoryOrRegisterReference() = default;
 
-    DeprecatedString to_deprecated_string(Instruction const&) const;
-    DeprecatedString to_deprecated_string_a16() const;
-    DeprecatedString to_deprecated_string_a32() const;
-    DeprecatedString to_deprecated_string_a64() const;
+    ByteString to_byte_string(Instruction const&) const;
+    ByteString to_byte_string_a16() const;
+    ByteString to_byte_string_a32() const;
+    ByteString to_byte_string_a64() const;
 
     template<typename InstructionStreamType>
     void decode(InstructionStreamType&, AddressSize, bool has_rex_r, bool has_rex_x, bool has_rex_b);
@@ -646,7 +646,7 @@ public:
 
     unsigned length() const;
 
-    DeprecatedString mnemonic() const;
+    ByteString mnemonic() const;
 
     u8 op() const { return m_op; }
     u8 modrm_byte() const { return m_modrm.modrm_byte(); }
@@ -698,13 +698,13 @@ public:
     OperandSize operand_size() const { return m_operand_size; }
     ProcessorMode mode() const { return m_mode; }
 
-    DeprecatedString to_deprecated_string(u32 origin, SymbolProvider const* = nullptr, bool x32 = true) const;
+    ByteString to_byte_string(u32 origin, SymbolProvider const* = nullptr, bool x32 = true) const;
 
 private:
     template<typename InstructionStreamType>
     Instruction(InstructionStreamType&, ProcessorMode);
 
-    void to_deprecated_string_internal(StringBuilder&, u32 origin, SymbolProvider const*, bool x32) const;
+    void to_byte_string_internal(StringBuilder&, u32 origin, SymbolProvider const*, bool x32) const;
 
     StringView reg8_name() const;
     StringView reg16_name() const;
diff --git a/Userland/Libraries/LibXML/DOM/Document.h b/Userland/Libraries/LibXML/DOM/Document.h
index f34fa329d50..b725d89c020 100644
--- a/Userland/Libraries/LibXML/DOM/Document.h
+++ b/Userland/Libraries/LibXML/DOM/Document.h
@@ -20,14 +20,14 @@ enum class Version {
 };
 
 struct Doctype {
-    DeprecatedString type;
+    ByteString type;
     Vector<MarkupDeclaration> markup_declarations;
     Optional<ExternalID> external_id;
 };
 
 class Document {
 public:
-    explicit Document(NonnullOwnPtr<Node> root, Optional<Doctype> doctype, HashMap<Name, DeprecatedString> processing_instructions, Version version)
+    explicit Document(NonnullOwnPtr<Node> root, Optional<Doctype> doctype, HashMap<Name, ByteString> processing_instructions, Version version)
         : m_root(move(root))
         , m_processing_instructions(move(processing_instructions))
         , m_version(version)
@@ -38,7 +38,7 @@ public:
     Node& root() { return *m_root; }
     Node const& root() const { return *m_root; }
 
-    HashMap<Name, DeprecatedString> const& processing_instructions() const { return m_processing_instructions; }
+    HashMap<Name, ByteString> const& processing_instructions() const { return m_processing_instructions; }
 
     Version version() const { return m_version; }
 
@@ -46,7 +46,7 @@ public:
 
 private:
     NonnullOwnPtr<Node> m_root;
-    HashMap<Name, DeprecatedString> m_processing_instructions;
+    HashMap<Name, ByteString> m_processing_instructions;
     Version m_version;
     Optional<Doctype> m_explicit_doctype;
 };
diff --git a/Userland/Libraries/LibXML/DOM/DocumentTypeDeclaration.h b/Userland/Libraries/LibXML/DOM/DocumentTypeDeclaration.h
index 53fd2efe60f..38794d8de98 100644
--- a/Userland/Libraries/LibXML/DOM/DocumentTypeDeclaration.h
+++ b/Userland/Libraries/LibXML/DOM/DocumentTypeDeclaration.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashTable.h>
 #include <AK/Variant.h>
 #include <AK/Vector.h>
@@ -73,7 +73,7 @@ struct AttributeListDeclaration {
     };
     struct Enumeration {
         // FIXME: NMToken
-        HashTable<DeprecatedString> tokens;
+        HashTable<ByteString> tokens;
     };
     using Type = Variant<StringType, TokenizedType, NotationType, Enumeration>;
 
@@ -82,10 +82,10 @@ struct AttributeListDeclaration {
     struct Implied {
     };
     struct Fixed {
-        DeprecatedString value;
+        ByteString value;
     };
     struct DefaultValue {
-        DeprecatedString value;
+        ByteString value;
     };
 
     using Default = Variant<Required, Implied, Fixed, DefaultValue>;
@@ -100,11 +100,11 @@ struct AttributeListDeclaration {
 };
 
 struct PublicID {
-    DeprecatedString public_literal;
+    ByteString public_literal;
 };
 
 struct SystemID {
-    DeprecatedString system_literal;
+    ByteString system_literal;
 };
 
 struct ExternalID {
@@ -119,12 +119,12 @@ struct EntityDefinition {
 
 struct GEDeclaration {
     Name name;
-    Variant<DeprecatedString, EntityDefinition> definition;
+    Variant<ByteString, EntityDefinition> definition;
 };
 
 struct PEDeclaration {
     Name name;
-    Variant<DeprecatedString, ExternalID> definition;
+    Variant<ByteString, ExternalID> definition;
 };
 
 using EntityDeclaration = Variant<GEDeclaration, PEDeclaration>;
diff --git a/Userland/Libraries/LibXML/DOM/Node.h b/Userland/Libraries/LibXML/DOM/Node.h
index 77b71e62692..f223500878f 100644
--- a/Userland/Libraries/LibXML/DOM/Node.h
+++ b/Userland/Libraries/LibXML/DOM/Node.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/Variant.h>
 #include <AK/Vector.h>
@@ -16,7 +16,7 @@ namespace XML {
 
 struct Attribute {
     Name name;
-    DeprecatedString value;
+    ByteString value;
 };
 
 struct Offset {
@@ -30,11 +30,11 @@ struct Node {
         StringBuilder builder;
     };
     struct Comment {
-        DeprecatedString text;
+        ByteString text;
     };
     struct Element {
         Name name;
-        HashMap<Name, DeprecatedString> attributes;
+        HashMap<Name, ByteString> attributes;
         Vector<NonnullOwnPtr<Node>> children;
     };
 
diff --git a/Userland/Libraries/LibXML/FundamentalTypes.h b/Userland/Libraries/LibXML/FundamentalTypes.h
index b67a5d28290..5a03f3d0d49 100644
--- a/Userland/Libraries/LibXML/FundamentalTypes.h
+++ b/Userland/Libraries/LibXML/FundamentalTypes.h
@@ -6,11 +6,11 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 
 namespace XML {
 
 // FIXME: Maybe extend this to something more sophisticated?
-using Name = DeprecatedString;
+using Name = ByteString;
 
 }
diff --git a/Userland/Libraries/LibXML/Parser/Parser.cpp b/Userland/Libraries/LibXML/Parser/Parser.cpp
index c6c6503b335..03548bdeeec 100644
--- a/Userland/Libraries/LibXML/Parser/Parser.cpp
+++ b/Userland/Libraries/LibXML/Parser/Parser.cpp
@@ -246,7 +246,7 @@ ErrorOr<void, ParseError> Parser::parse_internal()
     if (auto it = find_if(matched_source.begin(), matched_source.end(), s_restricted_characters); !it.is_end()) {
         return parse_error(
             it.index(),
-            DeprecatedString::formatted("Invalid character #{:x} used in document", *it));
+            ByteString::formatted("Invalid character #{:x} used in document", *it));
     }
 
     if (!m_lexer.is_eof())
@@ -261,7 +261,7 @@ ErrorOr<void, ParseError> Parser::expect(StringView expected)
 
     if (!m_lexer.consume_specific(expected)) {
         if (m_options.treat_errors_as_fatal)
-            return parse_error(m_lexer.tell(), DeprecatedString::formatted("Expected '{}'", expected));
+            return parse_error(m_lexer.tell(), ByteString::formatted("Expected '{}'", expected));
     }
 
     rollback.disarm();
@@ -275,7 +275,7 @@ requires(IsCallableWithArguments<Pred, bool, char>) ErrorOr<StringView, ParseErr
     auto start = m_lexer.tell();
     if (!m_lexer.next_is(predicate)) {
         if (m_options.treat_errors_as_fatal)
-            return parse_error(m_lexer.tell(), DeprecatedString::formatted("Expected {}", description));
+            return parse_error(m_lexer.tell(), ByteString::formatted("Expected {}", description));
     }
 
     m_lexer.ignore();
@@ -296,7 +296,7 @@ requires(IsCallableWithArguments<Pred, bool, char>) ErrorOr<StringView, ParseErr
 
     if (m_lexer.tell() == start) {
         if (m_options.treat_errors_as_fatal) {
-            return parse_error(m_lexer.tell(), DeprecatedString::formatted("Expected {}", description));
+            return parse_error(m_lexer.tell(), ByteString::formatted("Expected {}", description));
         }
     }
 
@@ -378,7 +378,7 @@ ErrorOr<void, ParseError> Parser::parse_version_info()
         m_in_compatibility_mode = true;
     } else {
         if (version_string != "1.1" && m_options.treat_errors_as_fatal)
-            return parse_error(m_lexer.tell(), DeprecatedString::formatted("Expected '1.1', found '{}'", version_string));
+            return parse_error(m_lexer.tell(), ByteString::formatted("Expected '1.1', found '{}'", version_string));
     }
 
     m_version = Version::Version11;
@@ -524,7 +524,7 @@ ErrorOr<void, ParseError> Parser::parse_processing_instruction()
     auto accept = accept_rule();
 
     auto target = TRY(parse_processing_instruction_target());
-    DeprecatedString data;
+    ByteString data;
     if (auto result = skip_whitespace(Required::Yes); !result.is_error())
         data = m_lexer.consume_until("?>");
     TRY(expect("?>"sv));
@@ -576,7 +576,7 @@ ErrorOr<Name, ParseError> Parser::parse_name()
     builder.append(rest);
 
     rollback.disarm();
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // 2.8.28. doctypedecl, https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-doctypedecl
@@ -601,7 +601,7 @@ ErrorOr<void, ParseError> Parser::parse_doctype_decl()
                 if (resource_result.is_error()) {
                     return parse_error(
                         id_start,
-                        DeprecatedString::formatted("Failed to resolve external subset '{}': {}", doctype.external_id->system_id.system_literal, resource_result.error()));
+                        ByteString::formatted("Failed to resolve external subset '{}': {}", doctype.external_id->system_id.system_literal, resource_result.error()));
                 }
                 StringView resolved_source = resource_result.value();
                 TemporaryChange source { m_source, resolved_source };
@@ -610,7 +610,7 @@ ErrorOr<void, ParseError> Parser::parse_doctype_decl()
                 if (!m_lexer.is_eof()) {
                     return parse_error(
                         m_lexer.tell(),
-                        DeprecatedString::formatted("Failed to resolve external subset '{}': garbage after declarations", doctype.external_id->system_id.system_literal));
+                        ByteString::formatted("Failed to resolve external subset '{}': garbage after declarations", doctype.external_id->system_id.system_literal));
                 }
                 doctype.markup_declarations.extend(move(declarations));
             }
@@ -681,7 +681,7 @@ ErrorOr<NonnullOwnPtr<Node>, ParseError> Parser::parse_empty_element_tag()
     auto accept = accept_rule();
 
     auto name = TRY(parse_name());
-    HashMap<Name, DeprecatedString> attributes;
+    HashMap<Name, ByteString> attributes;
 
     while (true) {
         if (auto result = skip_whitespace(Required::Yes); result.is_error())
@@ -723,7 +723,7 @@ ErrorOr<Attribute, ParseError> Parser::parse_attribute()
 }
 
 // 2.3.10. AttValue, https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-AttValue
-ErrorOr<DeprecatedString, ParseError> Parser::parse_attribute_value()
+ErrorOr<ByteString, ParseError> Parser::parse_attribute_value()
 {
     auto rollback = rollback_point();
     auto rule = enter_rule();
@@ -740,7 +740,7 @@ ErrorOr<DeprecatedString, ParseError> Parser::parse_attribute_value()
     return text;
 }
 
-ErrorOr<DeprecatedString, ParseError> Parser::parse_attribute_value_inner(StringView disallow)
+ErrorOr<ByteString, ParseError> Parser::parse_attribute_value_inner(StringView disallow)
 {
     StringBuilder builder;
     while (true) {
@@ -754,7 +754,7 @@ ErrorOr<DeprecatedString, ParseError> Parser::parse_attribute_value_inner(String
 
         if (m_lexer.next_is('&')) {
             auto reference = TRY(parse_reference());
-            if (auto* char_reference = reference.get_pointer<DeprecatedString>())
+            if (auto* char_reference = reference.get_pointer<ByteString>())
                 builder.append(*char_reference);
             else
                 builder.append(TRY(resolve_reference(reference.get<EntityReference>(), ReferencePlacement::AttributeValue)));
@@ -762,14 +762,14 @@ ErrorOr<DeprecatedString, ParseError> Parser::parse_attribute_value_inner(String
             builder.append(m_lexer.consume());
         }
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // Char ::= [#x1-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]
 constexpr static auto s_characters = ranges_for_search<Range(0x1, 0xd7ff), Range(0xe000, 0xfffd), Range(0x10000, 0x10ffff)>();
 
 // 4.1.67. Reference, https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-Reference
-ErrorOr<Variant<Parser::EntityReference, DeprecatedString>, ParseError> Parser::parse_reference()
+ErrorOr<Variant<Parser::EntityReference, ByteString>, ParseError> Parser::parse_reference()
 {
     auto rollback = rollback_point();
     auto rule = enter_rule();
@@ -811,7 +811,7 @@ ErrorOr<Variant<Parser::EntityReference, DeprecatedString>, ParseError> Parser::
         builder.append_code_point(*code_point);
 
         rollback.disarm();
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 
     auto name = name_result.release_value();
@@ -833,7 +833,7 @@ ErrorOr<NonnullOwnPtr<Node>, ParseError> Parser::parse_start_tag()
     auto accept = accept_rule();
 
     auto name = TRY(parse_name());
-    HashMap<Name, DeprecatedString> attributes;
+    HashMap<Name, ByteString> attributes;
 
     while (true) {
         if (auto result = skip_whitespace(Required::Yes); result.is_error())
@@ -891,7 +891,7 @@ ErrorOr<void, ParseError> Parser::parse_content()
         if (auto result = parse_reference(); !result.is_error()) {
             auto reference = result.release_value();
             auto reference_offset = m_lexer.offset_for(node_start);
-            if (auto char_reference = reference.get_pointer<DeprecatedString>())
+            if (auto char_reference = reference.get_pointer<ByteString>())
                 append_text(*char_reference, reference_offset);
             else
                 append_text(TRY(resolve_reference(reference.get<EntityReference>(), ReferencePlacement::Content)), reference_offset);
@@ -1028,7 +1028,7 @@ ErrorOr<Optional<MarkupDeclaration>, ParseError> Parser::parse_markup_declaratio
 }
 
 // 2.8.28a DeclSep, https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-DeclSep
-ErrorOr<Optional<DeprecatedString>, ParseError> Parser::parse_declaration_separator()
+ErrorOr<Optional<ByteString>, ParseError> Parser::parse_declaration_separator()
 {
     auto rollback = rollback_point();
     auto rule = enter_rule();
@@ -1042,7 +1042,7 @@ ErrorOr<Optional<DeprecatedString>, ParseError> Parser::parse_declaration_separa
 
     if (auto result = skip_whitespace(Required::Yes); !result.is_error()) {
         rollback.disarm();
-        return Optional<DeprecatedString> {};
+        return Optional<ByteString> {};
     }
 
     return parse_error(m_lexer.tell(), "Expected either whitespace, or a PEReference");
@@ -1178,7 +1178,7 @@ ErrorOr<AttributeListDeclaration::Definition, ParseError> Parser::parse_attribut
         TRY(expect(")"sv));
         type = AttributeListDeclaration::NotationType { move(names) };
     } else {
-        HashTable<DeprecatedString> names;
+        HashTable<ByteString> names;
         TRY(expect("("sv));
         TRY(skip_whitespace());
         names.set(TRY(parse_nm_token()));
@@ -1463,7 +1463,7 @@ ErrorOr<EntityDeclaration, ParseError> Parser::parse_general_entity_declaration(
 {
     auto rollback = rollback_point();
     auto rule = enter_rule();
-    Variant<DeprecatedString, EntityDefinition, Empty> definition;
+    Variant<ByteString, EntityDefinition, Empty> definition;
 
     // GEDecl ::= '<!ENTITY' S Name S EntityDef S? '>'
     TRY(expect("<!ENTITY"sv));
@@ -1493,7 +1493,7 @@ ErrorOr<EntityDeclaration, ParseError> Parser::parse_general_entity_declaration(
     rollback.disarm();
     return GEDeclaration {
         move(name),
-        move(definition).downcast<DeprecatedString, EntityDefinition>(),
+        move(definition).downcast<ByteString, EntityDefinition>(),
     };
 }
 
@@ -1503,7 +1503,7 @@ ErrorOr<EntityDeclaration, ParseError> Parser::parse_parameter_entity_declaratio
     auto rollback = rollback_point();
     auto rule = enter_rule();
 
-    Variant<DeprecatedString, ExternalID, Empty> definition;
+    Variant<ByteString, ExternalID, Empty> definition;
     // PEDecl ::= '<!ENTITY' S '%' S Name S PEDef S? '>'
     TRY(expect("<!ENTITY"sv));
     auto accept = accept_rule();
@@ -1525,7 +1525,7 @@ ErrorOr<EntityDeclaration, ParseError> Parser::parse_parameter_entity_declaratio
     rollback.disarm();
     return PEDeclaration {
         move(name),
-        move(definition).downcast<DeprecatedString, ExternalID>(),
+        move(definition).downcast<ByteString, ExternalID>(),
     };
 }
 
@@ -1639,7 +1639,7 @@ ErrorOr<Name, ParseError> Parser::parse_notation_data_declaration()
 }
 
 // 2.3.9 EntityValue, https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-EntityValue
-ErrorOr<DeprecatedString, ParseError> Parser::parse_entity_value()
+ErrorOr<ByteString, ParseError> Parser::parse_entity_value()
 {
     auto rollback = rollback_point();
     auto rule = enter_rule();
@@ -1672,7 +1672,7 @@ ErrorOr<DeprecatedString, ParseError> Parser::parse_entity_value()
     TRY(expect(quote));
 
     rollback.disarm();
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 // 2.7.18 CDSect, https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-CDSect
@@ -1734,11 +1734,11 @@ ErrorOr<void, ParseError> Parser::parse_text_declaration()
     return {};
 }
 
-ErrorOr<DeprecatedString, ParseError> Parser::resolve_reference(EntityReference const& reference, ReferencePlacement placement)
+ErrorOr<ByteString, ParseError> Parser::resolve_reference(EntityReference const& reference, ReferencePlacement placement)
 {
     static HashTable<Name> reference_lookup {};
     if (reference_lookup.contains(reference.name))
-        return parse_error(m_lexer.tell(), DeprecatedString::formatted("Invalid recursive definition for '{}'", reference.name));
+        return parse_error(m_lexer.tell(), ByteString::formatted("Invalid recursive definition for '{}'", reference.name));
 
     reference_lookup.set(reference.name);
     ScopeGuard remove_lookup {
@@ -1747,7 +1747,7 @@ ErrorOr<DeprecatedString, ParseError> Parser::resolve_reference(EntityReference
         }
     };
 
-    Optional<DeprecatedString> resolved;
+    Optional<ByteString> resolved;
     if (m_doctype.has_value()) {
         // FIXME: Split these up and resolve them ahead of time.
         for (auto& declaration : m_doctype->markup_declarations) {
@@ -1760,23 +1760,23 @@ ErrorOr<DeprecatedString, ParseError> Parser::resolve_reference(EntityReference
             if (ge_declaration->name != reference.name)
                 continue;
             TRY(ge_declaration->definition.visit(
-                [&](DeprecatedString const& definition) -> ErrorOr<void, ParseError> {
+                [&](ByteString const& definition) -> ErrorOr<void, ParseError> {
                     resolved = definition;
                     return {};
                 },
                 [&](EntityDefinition const& definition) -> ErrorOr<void, ParseError> {
                     if (placement == ReferencePlacement::AttributeValue)
-                        return parse_error(m_lexer.tell(), DeprecatedString::formatted("Attribute references external entity '{}'", reference.name));
+                        return parse_error(m_lexer.tell(), ByteString::formatted("Attribute references external entity '{}'", reference.name));
 
                     if (definition.notation.has_value())
-                        return parse_error(0u, DeprecatedString::formatted("Entity reference to unparsed entity '{}'", reference.name));
+                        return parse_error(0u, ByteString::formatted("Entity reference to unparsed entity '{}'", reference.name));
 
                     if (!m_options.resolve_external_resource)
-                        return parse_error(0u, DeprecatedString::formatted("Failed to resolve external entity '{}'", reference.name));
+                        return parse_error(0u, ByteString::formatted("Failed to resolve external entity '{}'", reference.name));
 
                     auto result = m_options.resolve_external_resource(definition.id.system_id, definition.id.public_id);
                     if (result.is_error())
-                        return parse_error(0u, DeprecatedString::formatted("Failed to resolve external entity '{}': {}", reference.name, result.error()));
+                        return parse_error(0u, ByteString::formatted("Failed to resolve external entity '{}': {}", reference.name, result.error()));
 
                     resolved = result.release_value();
                     return {};
@@ -1796,7 +1796,7 @@ ErrorOr<DeprecatedString, ParseError> Parser::resolve_reference(EntityReference
             return "'";
         if (reference.name == "quot")
             return "\"";
-        return parse_error(0u, DeprecatedString::formatted("Reference to undeclared entity '{}'", reference.name));
+        return parse_error(0u, ByteString::formatted("Reference to undeclared entity '{}'", reference.name));
     }
 
     StringView resolved_source = *resolved;
diff --git a/Userland/Libraries/LibXML/Parser/Parser.h b/Userland/Libraries/LibXML/Parser/Parser.h
index 4dba7788cad..cf71d638523 100644
--- a/Userland/Libraries/LibXML/Parser/Parser.h
+++ b/Userland/Libraries/LibXML/Parser/Parser.h
@@ -6,8 +6,8 @@
 
 #pragma once
 
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Function.h>
 #include <AK/GenericLexer.h>
 #include <AK/HashMap.h>
@@ -23,16 +23,16 @@ namespace XML {
 
 struct ParseError {
     size_t offset;
-    DeprecatedString error;
+    ByteString error;
 };
 
 struct Listener {
     virtual ~Listener() { }
 
-    virtual void set_source(DeprecatedString) { }
+    virtual void set_source(ByteString) { }
     virtual void document_start() { }
     virtual void document_end() { }
-    virtual void element_start(Name const&, HashMap<Name, DeprecatedString> const&) { }
+    virtual void element_start(Name const&, HashMap<Name, ByteString> const&) { }
     virtual void element_end(Name const&) { }
     virtual void text(StringView) { }
     virtual void comment(StringView) { }
@@ -57,7 +57,7 @@ public:
         bool preserve_cdata { true };
         bool preserve_comments { false };
         bool treat_errors_as_fatal { true };
-        Function<ErrorOr<DeprecatedString>(SystemID const&, Optional<PublicID> const&)> resolve_external_resource {};
+        Function<ErrorOr<ByteString>(SystemID const&, Optional<PublicID> const&)> resolve_external_resource {};
     };
 
     Parser(StringView source, Options options)
@@ -94,7 +94,7 @@ private:
         AttributeValue,
         Content,
     };
-    ErrorOr<DeprecatedString, ParseError> resolve_reference(EntityReference const&, ReferencePlacement);
+    ErrorOr<ByteString, ParseError> resolve_reference(EntityReference const&, ReferencePlacement);
 
     enum class Required {
         No,
@@ -120,12 +120,12 @@ private:
     ErrorOr<Name, ParseError> parse_end_tag();
     ErrorOr<void, ParseError> parse_content();
     ErrorOr<Attribute, ParseError> parse_attribute();
-    ErrorOr<DeprecatedString, ParseError> parse_attribute_value();
-    ErrorOr<Variant<EntityReference, DeprecatedString>, ParseError> parse_reference();
+    ErrorOr<ByteString, ParseError> parse_attribute_value();
+    ErrorOr<Variant<EntityReference, ByteString>, ParseError> parse_reference();
     ErrorOr<StringView, ParseError> parse_char_data();
     ErrorOr<Vector<MarkupDeclaration>, ParseError> parse_internal_subset();
     ErrorOr<Optional<MarkupDeclaration>, ParseError> parse_markup_declaration();
-    ErrorOr<Optional<DeprecatedString>, ParseError> parse_declaration_separator();
+    ErrorOr<Optional<ByteString>, ParseError> parse_declaration_separator();
     ErrorOr<Vector<MarkupDeclaration>, ParseError> parse_external_subset_declaration();
     ErrorOr<ElementDeclaration, ParseError> parse_element_declaration();
     ErrorOr<AttributeListDeclaration, ParseError> parse_attribute_list_declaration();
@@ -140,12 +140,12 @@ private:
     ErrorOr<PublicID, ParseError> parse_public_id();
     ErrorOr<SystemID, ParseError> parse_system_id();
     ErrorOr<ExternalID, ParseError> parse_external_id();
-    ErrorOr<DeprecatedString, ParseError> parse_entity_value();
+    ErrorOr<ByteString, ParseError> parse_entity_value();
     ErrorOr<Name, ParseError> parse_notation_data_declaration();
     ErrorOr<StringView, ParseError> parse_public_id_literal();
     ErrorOr<StringView, ParseError> parse_system_id_literal();
     ErrorOr<StringView, ParseError> parse_cdata_section();
-    ErrorOr<DeprecatedString, ParseError> parse_attribute_value_inner(StringView disallow);
+    ErrorOr<ByteString, ParseError> parse_attribute_value_inner(StringView disallow);
     ErrorOr<Vector<MarkupDeclaration>, ParseError> parse_external_subset();
     ErrorOr<void, ParseError> parse_text_declaration();
 
@@ -198,7 +198,7 @@ private:
                 rule_name = rule_name.substring_view(6);
             m_parse_errors.append({
                 error.offset,
-                DeprecatedString::formatted("{}: {}", rule_name, error.error),
+                ByteString::formatted("{}: {}", rule_name, error.error),
             });
         }
         return error;
@@ -213,11 +213,11 @@ private:
     Node* m_entered_node { nullptr };
     Version m_version { Version::Version11 };
     bool m_in_compatibility_mode { false };
-    DeprecatedString m_encoding;
+    ByteString m_encoding;
     bool m_standalone { false };
-    HashMap<Name, DeprecatedString> m_processing_instructions;
+    HashMap<Name, ByteString> m_processing_instructions;
     struct AcceptedRule {
-        Optional<DeprecatedString> rule {};
+        Optional<ByteString> rule {};
         bool accept { false };
     } m_current_rule {};
 
diff --git a/Userland/Services/Clipboard/ClipboardClient.ipc b/Userland/Services/Clipboard/ClipboardClient.ipc
index c21c666c590..34a446dc8ab 100644
--- a/Userland/Services/Clipboard/ClipboardClient.ipc
+++ b/Userland/Services/Clipboard/ClipboardClient.ipc
@@ -2,5 +2,5 @@
 
 endpoint ClipboardClient
 {
-    clipboard_data_changed([UTF8] DeprecatedString mime_type) =|
+    clipboard_data_changed([UTF8] ByteString mime_type) =|
 }
diff --git a/Userland/Services/Clipboard/ClipboardServer.ipc b/Userland/Services/Clipboard/ClipboardServer.ipc
index 3bacac59e19..8444db2c325 100644
--- a/Userland/Services/Clipboard/ClipboardServer.ipc
+++ b/Userland/Services/Clipboard/ClipboardServer.ipc
@@ -2,6 +2,6 @@
 
 endpoint ClipboardServer
 {
-    get_clipboard_data() => (Core::AnonymousBuffer data, [UTF8] DeprecatedString mime_type, HashMap<DeprecatedString,DeprecatedString> metadata)
-    set_clipboard_data(Core::AnonymousBuffer data, [UTF8] DeprecatedString mime_type, HashMap<DeprecatedString,DeprecatedString> metadata) =|
+    get_clipboard_data() => (Core::AnonymousBuffer data, [UTF8] ByteString mime_type, HashMap<ByteString,ByteString> metadata)
+    set_clipboard_data(Core::AnonymousBuffer data, [UTF8] ByteString mime_type, HashMap<ByteString,ByteString> metadata) =|
 }
diff --git a/Userland/Services/Clipboard/ConnectionFromClient.cpp b/Userland/Services/Clipboard/ConnectionFromClient.cpp
index e42f14276e5..978993ed264 100644
--- a/Userland/Services/Clipboard/ConnectionFromClient.cpp
+++ b/Userland/Services/Clipboard/ConnectionFromClient.cpp
@@ -30,7 +30,7 @@ void ConnectionFromClient::die()
     s_connections.remove(client_id());
 }
 
-void ConnectionFromClient::set_clipboard_data(Core::AnonymousBuffer const& data, DeprecatedString const& mime_type, HashMap<DeprecatedString, DeprecatedString> const& metadata)
+void ConnectionFromClient::set_clipboard_data(Core::AnonymousBuffer const& data, ByteString const& mime_type, HashMap<ByteString, ByteString> const& metadata)
 {
     Storage::the().set_data(data, mime_type, metadata);
 }
diff --git a/Userland/Services/Clipboard/ConnectionFromClient.h b/Userland/Services/Clipboard/ConnectionFromClient.h
index 68ffa747df5..bfee4054811 100644
--- a/Userland/Services/Clipboard/ConnectionFromClient.h
+++ b/Userland/Services/Clipboard/ConnectionFromClient.h
@@ -30,7 +30,7 @@ private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>, int client_id);
 
     virtual Messages::ClipboardServer::GetClipboardDataResponse get_clipboard_data() override;
-    virtual void set_clipboard_data(Core::AnonymousBuffer const&, DeprecatedString const&, HashMap<DeprecatedString, DeprecatedString> const&) override;
+    virtual void set_clipboard_data(Core::AnonymousBuffer const&, ByteString const&, HashMap<ByteString, ByteString> const&) override;
 };
 
 }
diff --git a/Userland/Services/Clipboard/Storage.cpp b/Userland/Services/Clipboard/Storage.cpp
index 1b89344197d..b1c3e7b3bc4 100644
--- a/Userland/Services/Clipboard/Storage.cpp
+++ b/Userland/Services/Clipboard/Storage.cpp
@@ -14,7 +14,7 @@ Storage& Storage::the()
     return s_the;
 }
 
-void Storage::set_data(Core::AnonymousBuffer data, DeprecatedString const& mime_type, HashMap<DeprecatedString, DeprecatedString> const& metadata)
+void Storage::set_data(Core::AnonymousBuffer data, ByteString const& mime_type, HashMap<ByteString, ByteString> const& metadata)
 {
     m_buffer = move(data);
     m_data_size = data.size();
diff --git a/Userland/Services/Clipboard/Storage.h b/Userland/Services/Clipboard/Storage.h
index eb1dbeeb987..6908833577e 100644
--- a/Userland/Services/Clipboard/Storage.h
+++ b/Userland/Services/Clipboard/Storage.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <LibCore/AnonymousBuffer.h>
@@ -20,8 +20,8 @@ public:
 
     bool has_data() const { return m_buffer.is_valid(); }
 
-    DeprecatedString const& mime_type() const { return m_mime_type; }
-    HashMap<DeprecatedString, DeprecatedString> const& metadata() const { return m_metadata; }
+    ByteString const& mime_type() const { return m_mime_type; }
+    HashMap<ByteString, ByteString> const& metadata() const { return m_metadata; }
 
     u8 const* data() const
     {
@@ -37,7 +37,7 @@ public:
         return 0;
     }
 
-    void set_data(Core::AnonymousBuffer, DeprecatedString const& mime_type, HashMap<DeprecatedString, DeprecatedString> const& metadata);
+    void set_data(Core::AnonymousBuffer, ByteString const& mime_type, HashMap<ByteString, ByteString> const& metadata);
 
     Function<void()> on_content_change;
 
@@ -46,10 +46,10 @@ public:
 private:
     Storage() = default;
 
-    DeprecatedString m_mime_type;
+    ByteString m_mime_type;
     Core::AnonymousBuffer m_buffer;
     size_t m_data_size { 0 };
-    HashMap<DeprecatedString, DeprecatedString> m_metadata;
+    HashMap<ByteString, ByteString> m_metadata;
 };
 
 }
diff --git a/Userland/Services/ConfigServer/ConfigClient.ipc b/Userland/Services/ConfigServer/ConfigClient.ipc
index 39ea54622fd..f228a47aed1 100644
--- a/Userland/Services/ConfigServer/ConfigClient.ipc
+++ b/Userland/Services/ConfigServer/ConfigClient.ipc
@@ -1,10 +1,10 @@
 endpoint ConfigClient
 {
-    notify_changed_string_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key, DeprecatedString value) =|
-    notify_changed_i32_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key, i32 value) =|
-    notify_changed_u32_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key, u32 value) =|
-    notify_changed_bool_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key, bool value) =|
-    notify_removed_key(DeprecatedString domain, DeprecatedString group, DeprecatedString key) =|
-    notify_removed_group(DeprecatedString domain, DeprecatedString group) =|
-    notify_added_group(DeprecatedString domain, DeprecatedString group) =|
+    notify_changed_string_value(ByteString domain, ByteString group, ByteString key, ByteString value) =|
+    notify_changed_i32_value(ByteString domain, ByteString group, ByteString key, i32 value) =|
+    notify_changed_u32_value(ByteString domain, ByteString group, ByteString key, u32 value) =|
+    notify_changed_bool_value(ByteString domain, ByteString group, ByteString key, bool value) =|
+    notify_removed_key(ByteString domain, ByteString group, ByteString key) =|
+    notify_removed_group(ByteString domain, ByteString group) =|
+    notify_added_group(ByteString domain, ByteString group) =|
 }
diff --git a/Userland/Services/ConfigServer/ConfigServer.ipc b/Userland/Services/ConfigServer/ConfigServer.ipc
index e441b0d6333..2f5fe79b713 100644
--- a/Userland/Services/ConfigServer/ConfigServer.ipc
+++ b/Userland/Services/ConfigServer/ConfigServer.ipc
@@ -1,22 +1,22 @@
 endpoint ConfigServer
 {
-    pledge_domains(Vector<DeprecatedString> domains) =|
+    pledge_domains(Vector<ByteString> domains) =|
 
-    monitor_domain(DeprecatedString domain) =|
+    monitor_domain(ByteString domain) =|
 
-    list_config_groups(DeprecatedString domain) => (Vector<DeprecatedString> groups)
-    list_config_keys(DeprecatedString domain, DeprecatedString group) => (Vector<DeprecatedString> keys)
+    list_config_groups(ByteString domain) => (Vector<ByteString> groups)
+    list_config_keys(ByteString domain, ByteString group) => (Vector<ByteString> keys)
 
-    read_string_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key) => (Optional<DeprecatedString> value)
-    read_i32_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key) => (Optional<i32> value)
-    read_u32_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key) => (Optional<u32> value)
-    read_bool_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key) => (Optional<bool> value)
+    read_string_value(ByteString domain, ByteString group, ByteString key) => (Optional<ByteString> value)
+    read_i32_value(ByteString domain, ByteString group, ByteString key) => (Optional<i32> value)
+    read_u32_value(ByteString domain, ByteString group, ByteString key) => (Optional<u32> value)
+    read_bool_value(ByteString domain, ByteString group, ByteString key) => (Optional<bool> value)
 
-    write_string_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key, DeprecatedString value) => ()
-    write_i32_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key, i32 value) => ()
-    write_u32_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key, u32 value) => ()
-    write_bool_value(DeprecatedString domain, DeprecatedString group, DeprecatedString key, bool value)  => ()
-    remove_key_entry(DeprecatedString domain, DeprecatedString group, DeprecatedString key) => ()
-    remove_group_entry(DeprecatedString domain, DeprecatedString group) => ()
-    add_group_entry(DeprecatedString domain, DeprecatedString group)  => ()
+    write_string_value(ByteString domain, ByteString group, ByteString key, ByteString value) => ()
+    write_i32_value(ByteString domain, ByteString group, ByteString key, i32 value) => ()
+    write_u32_value(ByteString domain, ByteString group, ByteString key, u32 value) => ()
+    write_bool_value(ByteString domain, ByteString group, ByteString key, bool value)  => ()
+    remove_key_entry(ByteString domain, ByteString group, ByteString key) => ()
+    remove_group_entry(ByteString domain, ByteString group) => ()
+    add_group_entry(ByteString domain, ByteString group)  => ()
 }
diff --git a/Userland/Services/ConfigServer/ConnectionFromClient.cpp b/Userland/Services/ConfigServer/ConnectionFromClient.cpp
index 296b457e216..952b54b6a9f 100644
--- a/Userland/Services/ConfigServer/ConnectionFromClient.cpp
+++ b/Userland/Services/ConfigServer/ConnectionFromClient.cpp
@@ -15,15 +15,15 @@ namespace ConfigServer {
 static HashMap<int, RefPtr<ConnectionFromClient>> s_connections;
 
 struct CachedDomain {
-    DeprecatedString domain;
+    ByteString domain;
     NonnullRefPtr<Core::ConfigFile> config;
     RefPtr<Core::FileWatcher> watcher;
 };
 
-static HashMap<DeprecatedString, NonnullOwnPtr<CachedDomain>> s_cache;
+static HashMap<ByteString, NonnullOwnPtr<CachedDomain>> s_cache;
 static constexpr int s_disk_sync_delay_ms = 5'000;
 
-static void for_each_monitoring_connection(DeprecatedString const& domain, ConnectionFromClient* excluded_connection, Function<void(ConnectionFromClient&)> callback)
+static void for_each_monitoring_connection(ByteString const& domain, ConnectionFromClient* excluded_connection, Function<void(ConnectionFromClient&)> callback)
 {
     for (auto& it : s_connections) {
         if (it.value->is_monitoring_domain(domain) && (!excluded_connection || it.value != excluded_connection))
@@ -31,7 +31,7 @@ static void for_each_monitoring_connection(DeprecatedString const& domain, Conne
     }
 }
 
-static Core::ConfigFile& ensure_domain_config(DeprecatedString const& domain)
+static Core::ConfigFile& ensure_domain_config(ByteString const& domain)
 {
     auto it = s_cache.find(domain);
     if (it != s_cache.end())
@@ -88,7 +88,7 @@ void ConnectionFromClient::die()
     sync_dirty_domains_to_disk();
 }
 
-void ConnectionFromClient::pledge_domains(Vector<DeprecatedString> const& domains)
+void ConnectionFromClient::pledge_domains(Vector<ByteString> const& domains)
 {
     if (m_has_pledged) {
         did_misbehave("Tried to pledge domains twice.");
@@ -99,7 +99,7 @@ void ConnectionFromClient::pledge_domains(Vector<DeprecatedString> const& domain
         m_pledged_domains.set(domain);
 }
 
-void ConnectionFromClient::monitor_domain(DeprecatedString const& domain)
+void ConnectionFromClient::monitor_domain(ByteString const& domain)
 {
     if (m_has_pledged && !m_pledged_domains.contains(domain)) {
         did_misbehave("Attempt to monitor non-pledged domain");
@@ -109,13 +109,13 @@ void ConnectionFromClient::monitor_domain(DeprecatedString const& domain)
     m_monitored_domains.set(domain);
 }
 
-bool ConnectionFromClient::validate_access(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key)
+bool ConnectionFromClient::validate_access(ByteString const& domain, ByteString const& group, ByteString const& key)
 {
     if (!m_has_pledged)
         return true;
     if (m_pledged_domains.contains(domain))
         return true;
-    did_misbehave(DeprecatedString::formatted("Blocked attempt to access domain '{}', group={}, key={}", domain, group, key).characters());
+    did_misbehave(ByteString::formatted("Blocked attempt to access domain '{}', group={}, key={}", domain, group, key).characters());
     return false;
 }
 
@@ -135,34 +135,34 @@ void ConnectionFromClient::sync_dirty_domains_to_disk()
     }
 }
 
-Messages::ConfigServer::ListConfigKeysResponse ConnectionFromClient::list_config_keys(DeprecatedString const& domain, DeprecatedString const& group)
+Messages::ConfigServer::ListConfigKeysResponse ConnectionFromClient::list_config_keys(ByteString const& domain, ByteString const& group)
 {
     if (!validate_access(domain, group, ""))
-        return Vector<DeprecatedString> {};
+        return Vector<ByteString> {};
     auto& config = ensure_domain_config(domain);
     return { config.keys(group) };
 }
 
-Messages::ConfigServer::ListConfigGroupsResponse ConnectionFromClient::list_config_groups(DeprecatedString const& domain)
+Messages::ConfigServer::ListConfigGroupsResponse ConnectionFromClient::list_config_groups(ByteString const& domain)
 {
     if (!validate_access(domain, "", ""))
-        return Vector<DeprecatedString> {};
+        return Vector<ByteString> {};
     auto& config = ensure_domain_config(domain);
     return { config.groups() };
 }
 
-Messages::ConfigServer::ReadStringValueResponse ConnectionFromClient::read_string_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key)
+Messages::ConfigServer::ReadStringValueResponse ConnectionFromClient::read_string_value(ByteString const& domain, ByteString const& group, ByteString const& key)
 {
     if (!validate_access(domain, group, key))
         return nullptr;
 
     auto& config = ensure_domain_config(domain);
     if (!config.has_key(group, key))
-        return Optional<DeprecatedString> {};
-    return Optional<DeprecatedString> { config.read_entry(group, key) };
+        return Optional<ByteString> {};
+    return Optional<ByteString> { config.read_entry(group, key) };
 }
 
-Messages::ConfigServer::ReadI32ValueResponse ConnectionFromClient::read_i32_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key)
+Messages::ConfigServer::ReadI32ValueResponse ConnectionFromClient::read_i32_value(ByteString const& domain, ByteString const& group, ByteString const& key)
 {
     if (!validate_access(domain, group, key))
         return nullptr;
@@ -173,7 +173,7 @@ Messages::ConfigServer::ReadI32ValueResponse ConnectionFromClient::read_i32_valu
     return Optional<i32> { config.read_num_entry(group, key) };
 }
 
-Messages::ConfigServer::ReadU32ValueResponse ConnectionFromClient::read_u32_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key)
+Messages::ConfigServer::ReadU32ValueResponse ConnectionFromClient::read_u32_value(ByteString const& domain, ByteString const& group, ByteString const& key)
 {
     if (!validate_access(domain, group, key))
         return nullptr;
@@ -184,7 +184,7 @@ Messages::ConfigServer::ReadU32ValueResponse ConnectionFromClient::read_u32_valu
     return Optional<u32> { config.read_num_entry<u32>(group, key) };
 }
 
-Messages::ConfigServer::ReadBoolValueResponse ConnectionFromClient::read_bool_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key)
+Messages::ConfigServer::ReadBoolValueResponse ConnectionFromClient::read_bool_value(ByteString const& domain, ByteString const& group, ByteString const& key)
 {
     if (!validate_access(domain, group, key))
         return nullptr;
@@ -203,7 +203,7 @@ void ConnectionFromClient::start_or_restart_sync_timer()
         m_sync_timer->start();
 }
 
-void ConnectionFromClient::write_string_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, DeprecatedString const& value)
+void ConnectionFromClient::write_string_value(ByteString const& domain, ByteString const& group, ByteString const& key, ByteString const& value)
 {
     if (!validate_access(domain, group, key))
         return;
@@ -222,7 +222,7 @@ void ConnectionFromClient::write_string_value(DeprecatedString const& domain, De
     });
 }
 
-void ConnectionFromClient::write_i32_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, i32 value)
+void ConnectionFromClient::write_i32_value(ByteString const& domain, ByteString const& group, ByteString const& key, i32 value)
 {
     if (!validate_access(domain, group, key))
         return;
@@ -241,7 +241,7 @@ void ConnectionFromClient::write_i32_value(DeprecatedString const& domain, Depre
     });
 }
 
-void ConnectionFromClient::write_u32_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, u32 value)
+void ConnectionFromClient::write_u32_value(ByteString const& domain, ByteString const& group, ByteString const& key, u32 value)
 {
     if (!validate_access(domain, group, key))
         return;
@@ -260,7 +260,7 @@ void ConnectionFromClient::write_u32_value(DeprecatedString const& domain, Depre
     });
 }
 
-void ConnectionFromClient::write_bool_value(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key, bool value)
+void ConnectionFromClient::write_bool_value(ByteString const& domain, ByteString const& group, ByteString const& key, bool value)
 {
     if (!validate_access(domain, group, key))
         return;
@@ -279,7 +279,7 @@ void ConnectionFromClient::write_bool_value(DeprecatedString const& domain, Depr
     });
 }
 
-void ConnectionFromClient::remove_key_entry(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key)
+void ConnectionFromClient::remove_key_entry(ByteString const& domain, ByteString const& group, ByteString const& key)
 {
     if (!validate_access(domain, group, key))
         return;
@@ -297,7 +297,7 @@ void ConnectionFromClient::remove_key_entry(DeprecatedString const& domain, Depr
     });
 }
 
-void ConnectionFromClient::remove_group_entry(DeprecatedString const& domain, DeprecatedString const& group)
+void ConnectionFromClient::remove_group_entry(ByteString const& domain, ByteString const& group)
 {
     if (!validate_access(domain, group, {}))
         return;
@@ -315,7 +315,7 @@ void ConnectionFromClient::remove_group_entry(DeprecatedString const& domain, De
     });
 }
 
-void ConnectionFromClient::add_group_entry(DeprecatedString const& domain, DeprecatedString const& group)
+void ConnectionFromClient::add_group_entry(ByteString const& domain, ByteString const& group)
 {
     if (!validate_access(domain, group, {}))
         return;
diff --git a/Userland/Services/ConfigServer/ConnectionFromClient.h b/Userland/Services/ConfigServer/ConnectionFromClient.h
index 91e739d3e43..f64d25984ce 100644
--- a/Userland/Services/ConfigServer/ConnectionFromClient.h
+++ b/Userland/Services/ConfigServer/ConnectionFromClient.h
@@ -20,38 +20,38 @@ public:
 
     virtual void die() override;
 
-    bool is_monitoring_domain(DeprecatedString const& domain) const { return m_monitored_domains.contains(domain); }
+    bool is_monitoring_domain(ByteString const& domain) const { return m_monitored_domains.contains(domain); }
 
 private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>, int client_id);
 
-    virtual void pledge_domains(Vector<DeprecatedString> const&) override;
-    virtual void monitor_domain(DeprecatedString const&) override;
-    virtual Messages::ConfigServer::ListConfigGroupsResponse list_config_groups([[maybe_unused]] DeprecatedString const& domain) override;
-    virtual Messages::ConfigServer::ListConfigKeysResponse list_config_keys([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group) override;
-    virtual Messages::ConfigServer::ReadStringValueResponse read_string_value([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group, [[maybe_unused]] DeprecatedString const& key) override;
-    virtual Messages::ConfigServer::ReadI32ValueResponse read_i32_value([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group, [[maybe_unused]] DeprecatedString const& key) override;
-    virtual Messages::ConfigServer::ReadU32ValueResponse read_u32_value([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group, [[maybe_unused]] DeprecatedString const& key) override;
-    virtual Messages::ConfigServer::ReadBoolValueResponse read_bool_value([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group, [[maybe_unused]] DeprecatedString const& key) override;
-    virtual void write_string_value([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group, [[maybe_unused]] DeprecatedString const& key, [[maybe_unused]] DeprecatedString const& value) override;
-    virtual void write_i32_value([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group, [[maybe_unused]] DeprecatedString const& key, [[maybe_unused]] i32 value) override;
-    virtual void write_u32_value([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group, [[maybe_unused]] DeprecatedString const& key, [[maybe_unused]] u32 value) override;
-    virtual void write_bool_value([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group, [[maybe_unused]] DeprecatedString const& key, [[maybe_unused]] bool value) override;
-    virtual void remove_key_entry([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group, [[maybe_unused]] DeprecatedString const& key) override;
-    virtual void remove_group_entry([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group) override;
-    virtual void add_group_entry([[maybe_unused]] DeprecatedString const& domain, [[maybe_unused]] DeprecatedString const& group) override;
+    virtual void pledge_domains(Vector<ByteString> const&) override;
+    virtual void monitor_domain(ByteString const&) override;
+    virtual Messages::ConfigServer::ListConfigGroupsResponse list_config_groups([[maybe_unused]] ByteString const& domain) override;
+    virtual Messages::ConfigServer::ListConfigKeysResponse list_config_keys([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group) override;
+    virtual Messages::ConfigServer::ReadStringValueResponse read_string_value([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group, [[maybe_unused]] ByteString const& key) override;
+    virtual Messages::ConfigServer::ReadI32ValueResponse read_i32_value([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group, [[maybe_unused]] ByteString const& key) override;
+    virtual Messages::ConfigServer::ReadU32ValueResponse read_u32_value([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group, [[maybe_unused]] ByteString const& key) override;
+    virtual Messages::ConfigServer::ReadBoolValueResponse read_bool_value([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group, [[maybe_unused]] ByteString const& key) override;
+    virtual void write_string_value([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group, [[maybe_unused]] ByteString const& key, [[maybe_unused]] ByteString const& value) override;
+    virtual void write_i32_value([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group, [[maybe_unused]] ByteString const& key, [[maybe_unused]] i32 value) override;
+    virtual void write_u32_value([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group, [[maybe_unused]] ByteString const& key, [[maybe_unused]] u32 value) override;
+    virtual void write_bool_value([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group, [[maybe_unused]] ByteString const& key, [[maybe_unused]] bool value) override;
+    virtual void remove_key_entry([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group, [[maybe_unused]] ByteString const& key) override;
+    virtual void remove_group_entry([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group) override;
+    virtual void add_group_entry([[maybe_unused]] ByteString const& domain, [[maybe_unused]] ByteString const& group) override;
 
-    bool validate_access(DeprecatedString const& domain, DeprecatedString const& group, DeprecatedString const& key);
+    bool validate_access(ByteString const& domain, ByteString const& group, ByteString const& key);
     void sync_dirty_domains_to_disk();
     void start_or_restart_sync_timer();
 
     bool m_has_pledged { false };
-    HashTable<DeprecatedString> m_pledged_domains;
+    HashTable<ByteString> m_pledged_domains;
 
-    HashTable<DeprecatedString> m_monitored_domains;
+    HashTable<ByteString> m_monitored_domains;
 
     NonnullRefPtr<Core::Timer> m_sync_timer;
-    HashTable<DeprecatedString> m_dirty_domains;
+    HashTable<ByteString> m_dirty_domains;
 };
 
 }
diff --git a/Userland/Services/CrashDaemon/main.cpp b/Userland/Services/CrashDaemon/main.cpp
index 96662f2ae50..497c08541d9 100644
--- a/Userland/Services/CrashDaemon/main.cpp
+++ b/Userland/Services/CrashDaemon/main.cpp
@@ -17,7 +17,7 @@
 #include <time.h>
 #include <unistd.h>
 
-static void wait_until_coredump_is_ready(DeprecatedString const& coredump_path)
+static void wait_until_coredump_is_ready(ByteString const& coredump_path)
 {
     while (true) {
         struct stat statbuf;
@@ -32,7 +32,7 @@ static void wait_until_coredump_is_ready(DeprecatedString const& coredump_path)
     }
 }
 
-static void launch_crash_reporter(DeprecatedString const& coredump_path, bool unlink_on_exit)
+static void launch_crash_reporter(ByteString const& coredump_path, bool unlink_on_exit)
 {
     auto pid = Core::Process::spawn("/bin/CrashReporter"sv,
         unlink_on_exit
diff --git a/Userland/Services/DHCPClient/DHCPv4.h b/Userland/Services/DHCPClient/DHCPv4.h
index fbc9beee797..082aa42af2e 100644
--- a/Userland/Services/DHCPClient/DHCPv4.h
+++ b/Userland/Services/DHCPClient/DHCPv4.h
@@ -151,7 +151,7 @@ struct ParsedDHCPv4Options {
         return values;
     }
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
         StringBuilder builder;
         builder.append("DHCP Options ("sv);
@@ -163,7 +163,7 @@ struct ParsedDHCPv4Options {
                 builder.appendff(" {} ", ((u8 const*)opt.value.value)[i]);
             builder.append('\n');
         }
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 
     struct DHCPOptionValue {
diff --git a/Userland/Services/DHCPClient/DHCPv4Client.cpp b/Userland/Services/DHCPClient/DHCPv4Client.cpp
index 98f35180a0c..54a6ed6fb36 100644
--- a/Userland/Services/DHCPClient/DHCPv4Client.cpp
+++ b/Userland/Services/DHCPClient/DHCPv4Client.cpp
@@ -18,14 +18,14 @@
 #include <LibCore/Timer.h>
 #include <stdio.h>
 
-static u8 mac_part(Vector<DeprecatedString> const& parts, size_t index)
+static u8 mac_part(Vector<ByteString> const& parts, size_t index)
 {
     auto result = AK::StringUtils::convert_to_uint_from_hex(parts.at(index));
     VERIFY(result.has_value());
     return result.value();
 }
 
-static MACAddress mac_from_string(DeprecatedString const& str)
+static MACAddress mac_from_string(ByteString const& str)
 {
     auto chunks = str.split(':');
     VERIFY(chunks.size() == 6); // should we...worry about this?
@@ -117,7 +117,7 @@ static void set_params(InterfaceDescriptor const& iface, IPv4Address const& ipv4
     }
 }
 
-DHCPv4Client::DHCPv4Client(Vector<DeprecatedString> interfaces_with_dhcp_enabled)
+DHCPv4Client::DHCPv4Client(Vector<ByteString> interfaces_with_dhcp_enabled)
     : m_interfaces_with_dhcp_enabled(move(interfaces_with_dhcp_enabled))
 {
     m_server = Core::UDPServer::construct(this);
@@ -193,13 +193,13 @@ ErrorOr<DHCPv4Client::Interfaces> DHCPv4Client::get_discoverable_interfaces()
     json.value().as_array().for_each([&ifnames_to_immediately_discover, &ifnames_to_attempt_later](auto& value) {
         auto if_object = value.as_object();
 
-        if (if_object.get_deprecated_string("class_name"sv).value_or({}) == "LoopbackAdapter")
+        if (if_object.get_byte_string("class_name"sv).value_or({}) == "LoopbackAdapter")
             return;
 
-        auto name = if_object.get_deprecated_string("name"sv).value_or({});
-        auto mac = if_object.get_deprecated_string("mac_address"sv).value_or({});
+        auto name = if_object.get_byte_string("name"sv).value_or({});
+        auto mac = if_object.get_byte_string("mac_address"sv).value_or({});
         auto is_up = if_object.get_bool("link_up"sv).value_or(false);
-        auto ipv4_addr_maybe = IPv4Address::from_string(if_object.get_deprecated_string("ipv4_address"sv).value_or({}));
+        auto ipv4_addr_maybe = IPv4Address::from_string(if_object.get_byte_string("ipv4_address"sv).value_or({}));
         auto ipv4_addr = ipv4_addr_maybe.has_value() ? ipv4_addr_maybe.value() : IPv4Address { 0, 0, 0, 0 };
         if (is_up) {
             dbgln_if(DHCPV4_DEBUG, "Found adapter '{}' with mac {}, and it was up!", name, mac);
@@ -218,7 +218,7 @@ ErrorOr<DHCPv4Client::Interfaces> DHCPv4Client::get_discoverable_interfaces()
 
 void DHCPv4Client::handle_offer(DHCPv4Packet const& packet, ParsedDHCPv4Options const& options)
 {
-    dbgln("We were offered {} for {}", packet.yiaddr().to_deprecated_string(), options.get<u32>(DHCPOption::IPAddressLeaseTime).value_or(0));
+    dbgln("We were offered {} for {}", packet.yiaddr().to_byte_string(), options.get<u32>(DHCPOption::IPAddressLeaseTime).value_or(0));
     auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
     if (!transaction) {
         dbgln("we're not looking for {}", packet.xid());
@@ -239,8 +239,8 @@ void DHCPv4Client::handle_offer(DHCPv4Packet const& packet, ParsedDHCPv4Options
 void DHCPv4Client::handle_ack(DHCPv4Packet const& packet, ParsedDHCPv4Options const& options)
 {
     if constexpr (DHCPV4CLIENT_DEBUG) {
-        dbgln("The DHCP server handed us {}", packet.yiaddr().to_deprecated_string());
-        dbgln("Here are the options: {}", options.to_deprecated_string());
+        dbgln("The DHCP server handed us {}", packet.yiaddr().to_byte_string());
+        dbgln("Here are the options: {}", options.to_byte_string());
     }
 
     auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
@@ -273,8 +273,8 @@ void DHCPv4Client::handle_ack(DHCPv4Packet const& packet, ParsedDHCPv4Options co
 
 void DHCPv4Client::handle_nak(DHCPv4Packet const& packet, ParsedDHCPv4Options const& options)
 {
-    dbgln("The DHCP server told us to go chase our own tail about {}", packet.yiaddr().to_deprecated_string());
-    dbgln("Here are the options: {}", options.to_deprecated_string());
+    dbgln("The DHCP server told us to go chase our own tail about {}", packet.yiaddr().to_byte_string());
+    dbgln("Here are the options: {}", options.to_byte_string());
     // make another request a bit later :shrug:
     auto* transaction = const_cast<DHCPv4Transaction*>(m_ongoing_transactions.get(packet.xid()).value_or(nullptr));
     if (!transaction) {
@@ -297,7 +297,7 @@ void DHCPv4Client::process_incoming(DHCPv4Packet const& packet)
 {
     auto options = packet.parse_options();
 
-    dbgln_if(DHCPV4CLIENT_DEBUG, "Here are the options: {}", options.to_deprecated_string());
+    dbgln_if(DHCPV4CLIENT_DEBUG, "Here are the options: {}", options.to_byte_string());
 
     auto value_or_error = options.get<DHCPMessageType>(DHCPOption::DHCPMessageType);
     if (!value_or_error.has_value())
@@ -336,7 +336,7 @@ void DHCPv4Client::dhcp_discover(InterfaceDescriptor const& iface)
     if constexpr (DHCPV4CLIENT_DEBUG) {
         dbgln("Trying to lease an IP for {} with ID {}", iface.ifname, transaction_id);
         if (!iface.current_ip_address.is_zero())
-            dbgln("going to request the server to hand us {}", iface.current_ip_address.to_deprecated_string());
+            dbgln("going to request the server to hand us {}", iface.current_ip_address.to_byte_string());
     }
 
     DHCPv4PacketBuilder builder;
@@ -364,7 +364,7 @@ void DHCPv4Client::dhcp_discover(InterfaceDescriptor const& iface)
 void DHCPv4Client::dhcp_request(DHCPv4Transaction& transaction, DHCPv4Packet const& offer)
 {
     auto& iface = transaction.interface;
-    dbgln("Leasing the IP {} for adapter {}", offer.yiaddr().to_deprecated_string(), iface.ifname);
+    dbgln("Leasing the IP {} for adapter {}", offer.yiaddr().to_byte_string(), iface.ifname);
     DHCPv4PacketBuilder builder;
 
     DHCPv4Packet& packet = builder.peek();
diff --git a/Userland/Services/DHCPClient/DHCPv4Client.h b/Userland/Services/DHCPClient/DHCPv4Client.h
index 9b77ce0b679..03e91e1a85d 100644
--- a/Userland/Services/DHCPClient/DHCPv4Client.h
+++ b/Userland/Services/DHCPClient/DHCPv4Client.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include "DHCPv4.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
@@ -19,7 +19,7 @@
 #include <sys/socket.h>
 
 struct InterfaceDescriptor {
-    DeprecatedString ifname;
+    ByteString ifname;
     MACAddress mac_address;
     IPv4Address current_ip_address;
 };
@@ -54,11 +54,11 @@ public:
     static ErrorOr<Interfaces> get_discoverable_interfaces();
 
 private:
-    explicit DHCPv4Client(Vector<DeprecatedString> interfaces_with_dhcp_enabled);
+    explicit DHCPv4Client(Vector<ByteString> interfaces_with_dhcp_enabled);
 
     void try_discover_ifs();
 
-    Vector<DeprecatedString> m_interfaces_with_dhcp_enabled;
+    Vector<ByteString> m_interfaces_with_dhcp_enabled;
     HashMap<u32, OwnPtr<DHCPv4Transaction>> m_ongoing_transactions;
     RefPtr<Core::UDPServer> m_server;
     RefPtr<Core::Timer> m_check_timer;
diff --git a/Userland/Services/DHCPClient/main.cpp b/Userland/Services/DHCPClient/main.cpp
index cfcb2118d49..fe980b92c0c 100644
--- a/Userland/Services/DHCPClient/main.cpp
+++ b/Userland/Services/DHCPClient/main.cpp
@@ -12,7 +12,7 @@
 
 ErrorOr<int> serenity_main(Main::Arguments args)
 {
-    Vector<DeprecatedString> interfaces;
+    Vector<ByteString> interfaces;
 
     Core::ArgsParser parser;
     parser.add_positional_argument(interfaces, "Interfaces to run DHCP server on", "interfaces");
diff --git a/Userland/Services/FileOperation/main.cpp b/Userland/Services/FileOperation/main.cpp
index 7363b760a81..6d9ce25ec30 100644
--- a/Userland/Services/FileOperation/main.cpp
+++ b/Userland/Services/FileOperation/main.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/LexicalPath.h>
 #include <AK/StringView.h>
@@ -26,24 +26,24 @@ struct WorkItem {
         DeleteFile,
     };
     Type type;
-    DeprecatedString source;
-    DeprecatedString destination;
+    ByteString source;
+    ByteString destination;
     off_t size;
     mode_t mode { 0 };
 };
 
 static void report_warning(StringView message);
 static void report_error(StringView message);
-static ErrorOr<int> perform_copy(Vector<StringView> const& sources, DeprecatedString const& destination);
-static ErrorOr<int> perform_move(Vector<StringView> const& sources, DeprecatedString const& destination);
+static ErrorOr<int> perform_copy(Vector<StringView> const& sources, ByteString const& destination);
+static ErrorOr<int> perform_move(Vector<StringView> const& sources, ByteString const& destination);
 static ErrorOr<int> perform_delete(Vector<StringView> const& sources);
 static ErrorOr<int> execute_work_items(Vector<WorkItem> const& items);
-static ErrorOr<NonnullOwnPtr<Core::File>> open_destination_file(DeprecatedString const& destination, mode_t mode);
-static DeprecatedString deduplicate_destination_file_name(DeprecatedString const& destination);
+static ErrorOr<NonnullOwnPtr<Core::File>> open_destination_file(ByteString const& destination, mode_t mode);
+static ByteString deduplicate_destination_file_name(ByteString const& destination);
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
-    DeprecatedString operation;
+    ByteString operation;
     Vector<StringView> paths;
 
     Core::ArgsParser args_parser;
@@ -54,7 +54,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     if (operation == "Delete")
         return perform_delete(paths);
 
-    DeprecatedString destination = paths.take_last();
+    ByteString destination = paths.take_last();
     if (paths.is_empty())
         return Error::from_string_literal("At least one source and destination are required");
 
@@ -64,7 +64,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return perform_move(paths, destination);
 
     // FIXME: Return the formatted string directly. There is no way to do this right now without the temporary going out of scope and being destroyed.
-    report_error(DeprecatedString::formatted("Unknown operation '{}'", operation));
+    report_error(ByteString::formatted("Unknown operation '{}'", operation));
     return Error::from_string_literal("Unknown operation");
 }
 
@@ -78,7 +78,7 @@ static void report_error(StringView message)
     outln("ERROR {}", message);
 }
 
-static ErrorOr<int> collect_copy_work_items(DeprecatedString const& source, DeprecatedString const& destination, Vector<WorkItem>& items)
+static ErrorOr<int> collect_copy_work_items(ByteString const& source, ByteString const& destination, Vector<WorkItem>& items)
 {
     auto const st = TRY(Core::System::lstat(source));
     if (!S_ISDIR(st.st_mode)) {
@@ -114,7 +114,7 @@ static ErrorOr<int> collect_copy_work_items(DeprecatedString const& source, Depr
     return 0;
 }
 
-ErrorOr<int> perform_copy(Vector<StringView> const& sources, DeprecatedString const& destination)
+ErrorOr<int> perform_copy(Vector<StringView> const& sources, ByteString const& destination)
 {
     Vector<WorkItem> items;
 
@@ -125,7 +125,7 @@ ErrorOr<int> perform_copy(Vector<StringView> const& sources, DeprecatedString co
     return execute_work_items(items);
 }
 
-static ErrorOr<int> collect_move_work_items(DeprecatedString const& source, DeprecatedString const& destination, Vector<WorkItem>& items)
+static ErrorOr<int> collect_move_work_items(ByteString const& source, ByteString const& destination, Vector<WorkItem>& items)
 {
     auto const st = TRY(Core::System::lstat(source));
     if (!S_ISDIR(st.st_mode)) {
@@ -168,7 +168,7 @@ static ErrorOr<int> collect_move_work_items(DeprecatedString const& source, Depr
     return 0;
 }
 
-ErrorOr<int> perform_move(Vector<StringView> const& sources, DeprecatedString const& destination)
+ErrorOr<int> perform_move(Vector<StringView> const& sources, ByteString const& destination)
 {
     Vector<WorkItem> items;
 
@@ -179,7 +179,7 @@ ErrorOr<int> perform_move(Vector<StringView> const& sources, DeprecatedString co
     return execute_work_items(items);
 }
 
-static ErrorOr<int> collect_delete_work_items(DeprecatedString const& source, Vector<WorkItem>& items)
+static ErrorOr<int> collect_delete_work_items(ByteString const& source, Vector<WorkItem>& items)
 {
     if (auto const st = TRY(Core::System::lstat(source)); !S_ISDIR(st.st_mode)) {
         // It's a file.
@@ -235,7 +235,7 @@ ErrorOr<int> execute_work_items(Vector<WorkItem> const& items)
             outln("PROGRESS {} {} {} {} {} {} {}", i, items.size(), executed_work_bytes, total_work_bytes, item_done, item.size, item.source);
         };
 
-        auto copy_file = [&](DeprecatedString const& source, DeprecatedString const& destination, mode_t mode) -> ErrorOr<int> {
+        auto copy_file = [&](ByteString const& source, ByteString const& destination, mode_t mode) -> ErrorOr<int> {
             auto source_file = TRY(Core::File::open(source, Core::File::OpenMode::Read));
             // FIXME: When the file already exists, let the user choose the next action instead of renaming it by default.
             auto destination_file = TRY(open_destination_file(destination, mode));
@@ -248,7 +248,7 @@ ErrorOr<int> execute_work_items(Vector<WorkItem> const& items)
                     break;
                 if (auto result = destination_file->write_until_depleted(bytes_read); result.is_error()) {
                     // FIXME: Return the formatted string directly. There is no way to do this right now without the temporary going out of scope and being destroyed.
-                    report_warning(DeprecatedString::formatted("Failed to write to destination file: {}", result.error()));
+                    report_warning(ByteString::formatted("Failed to write to destination file: {}", result.error()));
                     return result.release_error();
                 }
                 item_done += bytes_read.size();
@@ -288,7 +288,7 @@ ErrorOr<int> execute_work_items(Vector<WorkItem> const& items)
         }
 
         case WorkItem::Type::MoveFile: {
-            DeprecatedString destination = item.destination;
+            ByteString destination = item.destination;
             while (true) {
                 auto maybe_error = Core::System::rename(item.source, destination);
                 if (!maybe_error.is_error()) {
@@ -306,7 +306,7 @@ ErrorOr<int> execute_work_items(Vector<WorkItem> const& items)
 
                 if (error_code != EXDEV) {
                     // FIXME: Return the formatted string directly. There is no way to do this right now without the temporary going out of scope and being destroyed.
-                    report_warning(DeprecatedString::formatted("Failed to move {}: {}", item.source, strerror(error_code)));
+                    report_warning(ByteString::formatted("Failed to move {}: {}", item.source, strerror(error_code)));
                     return Error::from_errno(error_code);
                 }
 
@@ -338,7 +338,7 @@ ErrorOr<int> execute_work_items(Vector<WorkItem> const& items)
     return 0;
 }
 
-ErrorOr<NonnullOwnPtr<Core::File>> open_destination_file(DeprecatedString const& destination, mode_t mode)
+ErrorOr<NonnullOwnPtr<Core::File>> open_destination_file(ByteString const& destination, mode_t mode)
 {
     auto old_mask = umask(0);
     auto destination_file_or_error = Core::File::open(destination, (Core::File::OpenMode::Write | Core::File::OpenMode::Truncate | Core::File::OpenMode::MustBeNew), mode);
@@ -349,7 +349,7 @@ ErrorOr<NonnullOwnPtr<Core::File>> open_destination_file(DeprecatedString const&
     return destination_file_or_error;
 }
 
-DeprecatedString deduplicate_destination_file_name(DeprecatedString const& destination)
+ByteString deduplicate_destination_file_name(ByteString const& destination)
 {
     LexicalPath destination_path(destination);
     auto title_without_counter = destination_path.title();
@@ -372,5 +372,5 @@ DeprecatedString deduplicate_destination_file_name(DeprecatedString const& desti
         basename.append(destination_path.extension());
     }
 
-    return LexicalPath::join(destination_path.dirname(), basename.to_deprecated_string()).string();
+    return LexicalPath::join(destination_path.dirname(), basename.to_byte_string()).string();
 }
diff --git a/Userland/Services/FileSystemAccessServer/ConnectionFromClient.cpp b/Userland/Services/FileSystemAccessServer/ConnectionFromClient.cpp
index 35529ea2d14..9040f6a041f 100644
--- a/Userland/Services/FileSystemAccessServer/ConnectionFromClient.cpp
+++ b/Userland/Services/FileSystemAccessServer/ConnectionFromClient.cpp
@@ -27,7 +27,7 @@ void ConnectionFromClient::die()
     GUI::Application::the()->quit();
 }
 
-void ConnectionFromClient::request_file_handler(i32 request_id, i32 window_server_client_id, i32 parent_window_id, DeprecatedString const& path, Core::File::OpenMode requested_access, ShouldPrompt prompt)
+void ConnectionFromClient::request_file_handler(i32 request_id, i32 window_server_client_id, i32 parent_window_id, ByteString const& path, Core::File::OpenMode requested_access, ShouldPrompt prompt)
 {
     VERIFY(path.starts_with("/"sv));
 
@@ -41,7 +41,7 @@ void ConnectionFromClient::request_file_handler(i32 request_id, i32 window_serve
         approved = has_flag(maybe_permissions.value(), relevant_permissions);
 
     if (!approved) {
-        DeprecatedString access_string;
+        ByteString access_string;
 
         if (has_flag(requested_access, Core::File::OpenMode::ReadWrite))
             access_string = "read and write";
@@ -51,12 +51,12 @@ void ConnectionFromClient::request_file_handler(i32 request_id, i32 window_serve
             access_string = "write to";
 
         auto pid = this->socket().peer_pid().release_value_but_fixme_should_propagate_errors();
-        auto exe_link = LexicalPath("/proc").append(DeprecatedString::number(pid)).append("exe"sv).string();
+        auto exe_link = LexicalPath("/proc").append(ByteString::number(pid)).append("exe"sv).string();
         auto exe_path = FileSystem::real_path(exe_link).release_value_but_fixme_should_propagate_errors();
 
         if (prompt == ShouldPrompt::Yes) {
             VERIFY(window_server_client_id != -1 && parent_window_id != -1);
-            auto exe_name = LexicalPath::basename(exe_path.to_deprecated_string());
+            auto exe_name = LexicalPath::basename(exe_path.to_byte_string());
             auto text = String::formatted("Allow {} ({}) to {} \"{}\"?", exe_name, pid, access_string, path).release_value_but_fixme_should_propagate_errors();
             auto result = GUI::MessageBox::try_show({}, window_server_client_id, parent_window_id, text, "File Permissions Requested"sv).release_value_but_fixme_should_propagate_errors();
             approved = result == GUI::MessageBox::ExecResult::Yes;
@@ -88,40 +88,40 @@ void ConnectionFromClient::request_file_handler(i32 request_id, i32 window_serve
     }
 }
 
-void ConnectionFromClient::request_file_read_only_approved(i32 request_id, DeprecatedString const& path)
+void ConnectionFromClient::request_file_read_only_approved(i32 request_id, ByteString const& path)
 {
     request_file_handler(request_id, -1, -1, path, Core::File::OpenMode::Read, ShouldPrompt::No);
 }
 
-void ConnectionFromClient::request_file(i32 request_id, i32 window_server_client_id, i32 parent_window_id, DeprecatedString const& path, Core::File::OpenMode requested_access)
+void ConnectionFromClient::request_file(i32 request_id, i32 window_server_client_id, i32 parent_window_id, ByteString const& path, Core::File::OpenMode requested_access)
 {
     request_file_handler(request_id, window_server_client_id, parent_window_id, path, requested_access, ShouldPrompt::Yes);
 }
 
-void ConnectionFromClient::prompt_open_file(i32 request_id, i32 window_server_client_id, i32 parent_window_id, DeprecatedString const& window_title, DeprecatedString const& path_to_view, Core::File::OpenMode requested_access, Optional<Vector<GUI::FileTypeFilter>> const& allowed_file_types)
+void ConnectionFromClient::prompt_open_file(i32 request_id, i32 window_server_client_id, i32 parent_window_id, ByteString const& window_title, ByteString const& path_to_view, Core::File::OpenMode requested_access, Optional<Vector<GUI::FileTypeFilter>> const& allowed_file_types)
 {
     auto relevant_permissions = requested_access & (Core::File::OpenMode::Read | Core::File::OpenMode::Write);
     VERIFY(relevant_permissions != Core::File::OpenMode::NotOpen);
 
     auto user_picked_file = GUI::FilePicker::get_filepath({}, window_server_client_id, parent_window_id, GUI::FilePicker::Mode::Open, window_title, {}, path_to_view, allowed_file_types).release_value_but_fixme_should_propagate_errors();
-    auto user_picked_file_but_fixme_should_use_string = user_picked_file.has_value() ? user_picked_file.release_value().to_deprecated_string() : Optional<DeprecatedString> {};
+    auto user_picked_file_but_fixme_should_use_string = user_picked_file.has_value() ? user_picked_file.release_value().to_byte_string() : Optional<ByteString> {};
 
     prompt_helper(request_id, user_picked_file_but_fixme_should_use_string, requested_access);
 }
 
-void ConnectionFromClient::prompt_save_file(i32 request_id, i32 window_server_client_id, i32 parent_window_id, DeprecatedString const& name, DeprecatedString const& ext, DeprecatedString const& path_to_view, Core::File::OpenMode requested_access)
+void ConnectionFromClient::prompt_save_file(i32 request_id, i32 window_server_client_id, i32 parent_window_id, ByteString const& name, ByteString const& ext, ByteString const& path_to_view, Core::File::OpenMode requested_access)
 {
     auto relevant_permissions = requested_access & (Core::File::OpenMode::Read | Core::File::OpenMode::Write);
     VERIFY(relevant_permissions != Core::File::OpenMode::NotOpen);
 
     auto basename = String::formatted("{}.{}", name, ext).release_value_but_fixme_should_propagate_errors();
     auto user_picked_file = GUI::FilePicker::get_filepath({}, window_server_client_id, parent_window_id, GUI::FilePicker::Mode::Save, {}, basename, path_to_view).release_value_but_fixme_should_propagate_errors();
-    auto user_picked_file_but_fixme_should_use_string = user_picked_file.has_value() ? user_picked_file.release_value().to_deprecated_string() : Optional<DeprecatedString> {};
+    auto user_picked_file_but_fixme_should_use_string = user_picked_file.has_value() ? user_picked_file.release_value().to_byte_string() : Optional<ByteString> {};
 
     prompt_helper(request_id, user_picked_file_but_fixme_should_use_string, requested_access);
 }
 
-void ConnectionFromClient::prompt_helper(i32 request_id, Optional<DeprecatedString> const& user_picked_file, Core::File::OpenMode requested_access)
+void ConnectionFromClient::prompt_helper(i32 request_id, Optional<ByteString> const& user_picked_file, Core::File::OpenMode requested_access)
 {
     if (user_picked_file.has_value()) {
         VERIFY(user_picked_file->starts_with("/"sv));
@@ -141,7 +141,7 @@ void ConnectionFromClient::prompt_helper(i32 request_id, Optional<DeprecatedStri
             async_handle_prompt_end(request_id, 0, IPC::File(*file.release_value()), user_picked_file);
         }
     } else {
-        async_handle_prompt_end(request_id, ECANCELED, Optional<IPC::File> {}, Optional<DeprecatedString> {});
+        async_handle_prompt_end(request_id, ECANCELED, Optional<IPC::File> {}, Optional<ByteString> {});
     }
 }
 
diff --git a/Userland/Services/FileSystemAccessServer/ConnectionFromClient.h b/Userland/Services/FileSystemAccessServer/ConnectionFromClient.h
index b8664eb1dce..0a68f54ef1e 100644
--- a/Userland/Services/FileSystemAccessServer/ConnectionFromClient.h
+++ b/Userland/Services/FileSystemAccessServer/ConnectionFromClient.h
@@ -28,22 +28,22 @@ public:
 private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>);
 
-    virtual void request_file_read_only_approved(i32, DeprecatedString const&) override;
-    virtual void request_file(i32, i32, i32, DeprecatedString const&, Core::File::OpenMode) override;
-    virtual void prompt_open_file(i32, i32, i32, DeprecatedString const&, DeprecatedString const&, Core::File::OpenMode, Optional<Vector<GUI::FileTypeFilter>> const&) override;
-    virtual void prompt_save_file(i32, i32, i32, DeprecatedString const&, DeprecatedString const&, DeprecatedString const&, Core::File::OpenMode) override;
+    virtual void request_file_read_only_approved(i32, ByteString const&) override;
+    virtual void request_file(i32, i32, i32, ByteString const&, Core::File::OpenMode) override;
+    virtual void prompt_open_file(i32, i32, i32, ByteString const&, ByteString const&, Core::File::OpenMode, Optional<Vector<GUI::FileTypeFilter>> const&) override;
+    virtual void prompt_save_file(i32, i32, i32, ByteString const&, ByteString const&, ByteString const&, Core::File::OpenMode) override;
 
-    void prompt_helper(i32, Optional<DeprecatedString> const&, Core::File::OpenMode);
+    void prompt_helper(i32, Optional<ByteString> const&, Core::File::OpenMode);
 
     enum class ShouldPrompt {
         No,
         Yes
     };
-    void request_file_handler(i32, i32, i32, DeprecatedString const&, Core::File::OpenMode, ShouldPrompt);
+    void request_file_handler(i32, i32, i32, ByteString const&, Core::File::OpenMode, ShouldPrompt);
 
     virtual Messages::FileSystemAccessServer::ExposeWindowServerClientIdResponse expose_window_server_client_id() override;
 
-    HashMap<DeprecatedString, Core::File::OpenMode> m_approved_files;
+    HashMap<ByteString, Core::File::OpenMode> m_approved_files;
 };
 
 }
diff --git a/Userland/Services/FileSystemAccessServer/FileSystemAccessClient.ipc b/Userland/Services/FileSystemAccessServer/FileSystemAccessClient.ipc
index ef9b3c5205a..d8cfedb2161 100644
--- a/Userland/Services/FileSystemAccessServer/FileSystemAccessClient.ipc
+++ b/Userland/Services/FileSystemAccessServer/FileSystemAccessClient.ipc
@@ -1,4 +1,4 @@
 endpoint FileSystemAccessClient
 {
-    handle_prompt_end(i32 request_id, i32 error, Optional<IPC::File> fd, Optional<DeprecatedString> chosen_file) =|
+    handle_prompt_end(i32 request_id, i32 error, Optional<IPC::File> fd, Optional<ByteString> chosen_file) =|
 }
diff --git a/Userland/Services/FileSystemAccessServer/FileSystemAccessServer.ipc b/Userland/Services/FileSystemAccessServer/FileSystemAccessServer.ipc
index 75b517d1994..62263e72322 100644
--- a/Userland/Services/FileSystemAccessServer/FileSystemAccessServer.ipc
+++ b/Userland/Services/FileSystemAccessServer/FileSystemAccessServer.ipc
@@ -3,10 +3,10 @@
 
 endpoint FileSystemAccessServer
 {
-    request_file_read_only_approved(i32 request_id, DeprecatedString path) =|
-    request_file(i32 request_id, i32 window_server_client_id, i32 window_id, DeprecatedString path, Core::File::OpenMode requested_access) =|
-    prompt_open_file(i32 request_id, i32 window_server_client_id, i32 window_id, DeprecatedString window_title, DeprecatedString path_to_view, Core::File::OpenMode requested_access, Optional<Vector<GUI::FileTypeFilter>> allowed_file_types) =|
-    prompt_save_file(i32 request_id, i32 window_server_client_id, i32 window_id, DeprecatedString title, DeprecatedString ext, DeprecatedString path_to_view, Core::File::OpenMode requested_access) =|
+    request_file_read_only_approved(i32 request_id, ByteString path) =|
+    request_file(i32 request_id, i32 window_server_client_id, i32 window_id, ByteString path, Core::File::OpenMode requested_access) =|
+    prompt_open_file(i32 request_id, i32 window_server_client_id, i32 window_id, ByteString window_title, ByteString path_to_view, Core::File::OpenMode requested_access, Optional<Vector<GUI::FileTypeFilter>> allowed_file_types) =|
+    prompt_save_file(i32 request_id, i32 window_server_client_id, i32 window_id, ByteString title, ByteString ext, ByteString path_to_view, Core::File::OpenMode requested_access) =|
 
     expose_window_server_client_id() => (i32 client_id)
 }
diff --git a/Userland/Services/ImageDecoder/ConnectionFromClient.cpp b/Userland/Services/ImageDecoder/ConnectionFromClient.cpp
index 85c91024ed5..e7382169684 100644
--- a/Userland/Services/ImageDecoder/ConnectionFromClient.cpp
+++ b/Userland/Services/ImageDecoder/ConnectionFromClient.cpp
@@ -37,7 +37,7 @@ static void decode_image_to_bitmaps_and_durations_with_decoder(Gfx::ImageDecoder
     }
 }
 
-static void decode_image_to_details(Core::AnonymousBuffer const& encoded_buffer, Optional<DeprecatedString> const& known_mime_type, bool& is_animated, u32& loop_count, Vector<Gfx::ShareableBitmap>& bitmaps, Vector<u32>& durations)
+static void decode_image_to_details(Core::AnonymousBuffer const& encoded_buffer, Optional<ByteString> const& known_mime_type, bool& is_animated, u32& loop_count, Vector<Gfx::ShareableBitmap>& bitmaps, Vector<u32>& durations)
 {
     VERIFY(bitmaps.size() == 0);
     VERIFY(durations.size() == 0);
@@ -57,7 +57,7 @@ static void decode_image_to_details(Core::AnonymousBuffer const& encoded_buffer,
     decode_image_to_bitmaps_and_durations_with_decoder(*decoder, bitmaps, durations);
 }
 
-Messages::ImageDecoderServer::DecodeImageResponse ConnectionFromClient::decode_image(Core::AnonymousBuffer const& encoded_buffer, Optional<DeprecatedString> const& mime_type)
+Messages::ImageDecoderServer::DecodeImageResponse ConnectionFromClient::decode_image(Core::AnonymousBuffer const& encoded_buffer, Optional<ByteString> const& mime_type)
 {
     if (!encoded_buffer.is_valid()) {
         dbgln_if(IMAGE_DECODER_DEBUG, "Encoded data is invalid");
diff --git a/Userland/Services/ImageDecoder/ConnectionFromClient.h b/Userland/Services/ImageDecoder/ConnectionFromClient.h
index b679509c962..d982f31c2d8 100644
--- a/Userland/Services/ImageDecoder/ConnectionFromClient.h
+++ b/Userland/Services/ImageDecoder/ConnectionFromClient.h
@@ -26,7 +26,7 @@ public:
 private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>);
 
-    virtual Messages::ImageDecoderServer::DecodeImageResponse decode_image(Core::AnonymousBuffer const&, Optional<DeprecatedString> const& mime_type) override;
+    virtual Messages::ImageDecoderServer::DecodeImageResponse decode_image(Core::AnonymousBuffer const&, Optional<ByteString> const& mime_type) override;
 };
 
 }
diff --git a/Userland/Services/ImageDecoder/ImageDecoderServer.ipc b/Userland/Services/ImageDecoder/ImageDecoderServer.ipc
index a2d24f1952d..7fe3c721a36 100644
--- a/Userland/Services/ImageDecoder/ImageDecoderServer.ipc
+++ b/Userland/Services/ImageDecoder/ImageDecoderServer.ipc
@@ -3,5 +3,5 @@
 
 endpoint ImageDecoderServer
 {
-    decode_image(Core::AnonymousBuffer data, Optional<DeprecatedString> mime_type) => (bool is_animated, u32 loop_count, Vector<Gfx::ShareableBitmap> bitmaps, Vector<u32> durations)
+    decode_image(Core::AnonymousBuffer data, Optional<ByteString> mime_type) => (bool is_animated, u32 loop_count, Vector<Gfx::ShareableBitmap> bitmaps, Vector<u32> durations)
 }
diff --git a/Userland/Services/LaunchServer/ConnectionFromClient.cpp b/Userland/Services/LaunchServer/ConnectionFromClient.cpp
index af89d2f7899..6dddf74174f 100644
--- a/Userland/Services/LaunchServer/ConnectionFromClient.cpp
+++ b/Userland/Services/LaunchServer/ConnectionFromClient.cpp
@@ -24,7 +24,7 @@ void ConnectionFromClient::die()
     s_connections.remove(client_id());
 }
 
-Messages::LaunchServer::OpenUrlResponse ConnectionFromClient::open_url(URL const& url, DeprecatedString const& handler_name)
+Messages::LaunchServer::OpenUrlResponse ConnectionFromClient::open_url(URL const& url, ByteString const& handler_name)
 {
     if (!m_allowlist.is_empty()) {
         bool allowed = false;
@@ -39,7 +39,7 @@ Messages::LaunchServer::OpenUrlResponse ConnectionFromClient::open_url(URL const
         }
         if (!allowed) {
             // You are not on the list, go home!
-            did_misbehave(DeprecatedString::formatted("Client requested a combination of handler/URL that was not on the list: '{}' with '{}'", handler_name, url).characters());
+            did_misbehave(ByteString::formatted("Client requested a combination of handler/URL that was not on the list: '{}' with '{}'", handler_name, url).characters());
             return nullptr;
         }
     }
@@ -69,10 +69,10 @@ void ConnectionFromClient::add_allowed_url(URL const& url)
         return;
     }
 
-    m_allowlist.empend(DeprecatedString(), false, Vector<URL> { url });
+    m_allowlist.empend(ByteString(), false, Vector<URL> { url });
 }
 
-void ConnectionFromClient::add_allowed_handler_with_any_url(DeprecatedString const& handler_name)
+void ConnectionFromClient::add_allowed_handler_with_any_url(ByteString const& handler_name)
 {
     if (m_allowlist_is_sealed) {
         did_misbehave("Got request to add more allowed handlers after list was sealed");
@@ -87,7 +87,7 @@ void ConnectionFromClient::add_allowed_handler_with_any_url(DeprecatedString con
     m_allowlist.empend(handler_name, true, Vector<URL>());
 }
 
-void ConnectionFromClient::add_allowed_handler_with_only_specific_urls(DeprecatedString const& handler_name, Vector<URL> const& urls)
+void ConnectionFromClient::add_allowed_handler_with_only_specific_urls(ByteString const& handler_name, Vector<URL> const& urls)
 {
     if (m_allowlist_is_sealed) {
         did_misbehave("Got request to add more allowed handlers after list was sealed");
diff --git a/Userland/Services/LaunchServer/ConnectionFromClient.h b/Userland/Services/LaunchServer/ConnectionFromClient.h
index f09ee20e665..21905da5c63 100644
--- a/Userland/Services/LaunchServer/ConnectionFromClient.h
+++ b/Userland/Services/LaunchServer/ConnectionFromClient.h
@@ -22,16 +22,16 @@ public:
 private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>, int client_id);
 
-    virtual Messages::LaunchServer::OpenUrlResponse open_url(URL const&, DeprecatedString const&) override;
+    virtual Messages::LaunchServer::OpenUrlResponse open_url(URL const&, ByteString const&) override;
     virtual Messages::LaunchServer::GetHandlersForUrlResponse get_handlers_for_url(URL const&) override;
     virtual Messages::LaunchServer::GetHandlersWithDetailsForUrlResponse get_handlers_with_details_for_url(URL const&) override;
     virtual void add_allowed_url(URL const&) override;
-    virtual void add_allowed_handler_with_any_url(DeprecatedString const&) override;
-    virtual void add_allowed_handler_with_only_specific_urls(DeprecatedString const&, Vector<URL> const&) override;
+    virtual void add_allowed_handler_with_any_url(ByteString const&) override;
+    virtual void add_allowed_handler_with_only_specific_urls(ByteString const&, Vector<URL> const&) override;
     virtual void seal_allowlist() override;
 
     struct AllowlistEntry {
-        DeprecatedString handler_name;
+        ByteString handler_name;
         bool any_url { false };
         Vector<URL> urls;
     };
diff --git a/Userland/Services/LaunchServer/LaunchServer.ipc b/Userland/Services/LaunchServer/LaunchServer.ipc
index 43a58077a90..425eab0fe73 100644
--- a/Userland/Services/LaunchServer/LaunchServer.ipc
+++ b/Userland/Services/LaunchServer/LaunchServer.ipc
@@ -2,12 +2,12 @@
 
 endpoint LaunchServer
 {
-    open_url(URL url, DeprecatedString handler_name) => (bool response)
-    get_handlers_for_url(URL url) => (Vector<DeprecatedString> handlers)
-    get_handlers_with_details_for_url(URL url) => (Vector<DeprecatedString> handlers_details)
+    open_url(URL url, ByteString handler_name) => (bool response)
+    get_handlers_for_url(URL url) => (Vector<ByteString> handlers)
+    get_handlers_with_details_for_url(URL url) => (Vector<ByteString> handlers_details)
 
     add_allowed_url(URL url) => ()
-    add_allowed_handler_with_any_url(DeprecatedString handler_name) => ()
-    add_allowed_handler_with_only_specific_urls(DeprecatedString handler_name, Vector<URL> urls) => ()
+    add_allowed_handler_with_any_url(ByteString handler_name) => ()
+    add_allowed_handler_with_only_specific_urls(ByteString handler_name, Vector<URL> urls) => ()
     seal_allowlist() => ()
 }
diff --git a/Userland/Services/LaunchServer/Launcher.cpp b/Userland/Services/LaunchServer/Launcher.cpp
index bec6f978261..a538c8505e2 100644
--- a/Userland/Services/LaunchServer/Launcher.cpp
+++ b/Userland/Services/LaunchServer/Launcher.cpp
@@ -25,9 +25,9 @@
 namespace LaunchServer {
 
 static Launcher* s_the;
-static bool spawn(DeprecatedString executable, Vector<DeprecatedString> const& arguments);
+static bool spawn(ByteString executable, Vector<ByteString> const& arguments);
 
-DeprecatedString Handler::name_from_executable(StringView executable)
+ByteString Handler::name_from_executable(StringView executable)
 {
     auto separator = executable.find_last('/');
     if (separator.has_value()) {
@@ -37,14 +37,14 @@ DeprecatedString Handler::name_from_executable(StringView executable)
     return executable;
 }
 
-void Handler::from_executable(Type handler_type, DeprecatedString const& executable)
+void Handler::from_executable(Type handler_type, ByteString const& executable)
 {
     this->handler_type = handler_type;
     this->name = name_from_executable(executable);
     this->executable = executable;
 }
 
-DeprecatedString Handler::to_details_str() const
+ByteString Handler::to_details_str() const
 {
     StringBuilder builder;
     auto obj = MUST(JsonObjectSerializer<>::try_create(builder));
@@ -64,7 +64,7 @@ DeprecatedString Handler::to_details_str() const
         break;
     }
     MUST(obj.finish());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 Launcher::Launcher()
@@ -79,18 +79,18 @@ Launcher& Launcher::the()
     return *s_the;
 }
 
-void Launcher::load_handlers(DeprecatedString const& af_dir)
+void Launcher::load_handlers(ByteString const& af_dir)
 {
     Desktop::AppFile::for_each([&](auto af) {
         auto app_name = af->name();
         auto app_executable = af->executable();
-        HashTable<DeprecatedString> mime_types;
+        HashTable<ByteString> mime_types;
         for (auto& mime_type : af->launcher_mime_types())
             mime_types.set(mime_type);
-        HashTable<DeprecatedString> file_types;
+        HashTable<ByteString> file_types;
         for (auto& file_type : af->launcher_file_types())
             file_types.set(file_type);
-        HashTable<DeprecatedString> protocols;
+        HashTable<ByteString> protocols;
         for (auto& protocol : af->launcher_protocols())
             protocols.set(protocol);
         if (access(app_executable.characters(), X_OK) == 0)
@@ -129,7 +129,7 @@ void Launcher::load_config(Core::ConfigFile const& cfg)
     }
 }
 
-bool Launcher::has_mime_handlers(DeprecatedString const& mime_type)
+bool Launcher::has_mime_handlers(ByteString const& mime_type)
 {
     for (auto& handler : m_handlers)
         if (handler.value.mime_types.contains(mime_type))
@@ -137,17 +137,17 @@ bool Launcher::has_mime_handlers(DeprecatedString const& mime_type)
     return false;
 }
 
-Vector<DeprecatedString> Launcher::handlers_for_url(const URL& url)
+Vector<ByteString> Launcher::handlers_for_url(const URL& url)
 {
-    Vector<DeprecatedString> handlers;
+    Vector<ByteString> handlers;
     if (url.scheme() == "file") {
         for_each_handler_for_path(url.serialize_path(), [&](auto& handler) -> bool {
             handlers.append(handler.executable);
             return true;
         });
     } else {
-        for_each_handler(url.scheme().to_deprecated_string(), m_protocol_handlers, [&](auto const& handler) -> bool {
-            if (handler.handler_type != Handler::Type::Default || handler.protocols.contains(url.scheme().to_deprecated_string())) {
+        for_each_handler(url.scheme().to_byte_string(), m_protocol_handlers, [&](auto const& handler) -> bool {
+            if (handler.handler_type != Handler::Type::Default || handler.protocols.contains(url.scheme().to_byte_string())) {
                 handlers.append(handler.executable);
                 return true;
             }
@@ -157,17 +157,17 @@ Vector<DeprecatedString> Launcher::handlers_for_url(const URL& url)
     return handlers;
 }
 
-Vector<DeprecatedString> Launcher::handlers_with_details_for_url(const URL& url)
+Vector<ByteString> Launcher::handlers_with_details_for_url(const URL& url)
 {
-    Vector<DeprecatedString> handlers;
+    Vector<ByteString> handlers;
     if (url.scheme() == "file") {
         for_each_handler_for_path(url.serialize_path(), [&](auto& handler) -> bool {
             handlers.append(handler.to_details_str());
             return true;
         });
     } else {
-        for_each_handler(url.scheme().to_deprecated_string(), m_protocol_handlers, [&](auto const& handler) -> bool {
-            if (handler.handler_type != Handler::Type::Default || handler.protocols.contains(url.scheme().to_deprecated_string())) {
+        for_each_handler(url.scheme().to_byte_string(), m_protocol_handlers, [&](auto const& handler) -> bool {
+            if (handler.handler_type != Handler::Type::Default || handler.protocols.contains(url.scheme().to_byte_string())) {
                 handlers.append(handler.to_details_str());
                 return true;
             }
@@ -177,7 +177,7 @@ Vector<DeprecatedString> Launcher::handlers_with_details_for_url(const URL& url)
     return handlers;
 }
 
-Optional<StringView> Launcher::mime_type_for_file(DeprecatedString path)
+Optional<StringView> Launcher::mime_type_for_file(ByteString path)
 {
     auto file_or_error = Core::File::open(path, Core::File::OpenMode::Read);
     if (file_or_error.is_error())
@@ -186,7 +186,7 @@ Optional<StringView> Launcher::mime_type_for_file(DeprecatedString path)
     return Core::guess_mime_type_based_on_sniffed_bytes(*file_or_error.release_value());
 }
 
-bool Launcher::open_url(const URL& url, DeprecatedString const& handler_name)
+bool Launcher::open_url(const URL& url, ByteString const& handler_name)
 {
     if (!handler_name.is_empty())
         return open_with_handler_name(url, handler_name);
@@ -194,30 +194,30 @@ bool Launcher::open_url(const URL& url, DeprecatedString const& handler_name)
     if (url.scheme() == "file")
         return open_file_url(url);
 
-    return open_with_user_preferences(m_protocol_handlers, url.scheme().to_deprecated_string(), { url.to_deprecated_string() });
+    return open_with_user_preferences(m_protocol_handlers, url.scheme().to_byte_string(), { url.to_byte_string() });
 }
 
-bool Launcher::open_with_handler_name(const URL& url, DeprecatedString const& handler_name)
+bool Launcher::open_with_handler_name(const URL& url, ByteString const& handler_name)
 {
     auto handler_optional = m_handlers.get(handler_name);
     if (!handler_optional.has_value())
         return false;
 
     auto& handler = handler_optional.value();
-    DeprecatedString argument;
+    ByteString argument;
     if (url.scheme() == "file")
         argument = url.serialize_path();
     else
-        argument = url.to_deprecated_string();
+        argument = url.to_byte_string();
     return spawn(handler.executable, { argument });
 }
 
-bool spawn(DeprecatedString executable, Vector<DeprecatedString> const& arguments)
+bool spawn(ByteString executable, Vector<ByteString> const& arguments)
 {
     return !Core::Process::spawn(executable, arguments).is_error();
 }
 
-Handler Launcher::get_handler_for_executable(Handler::Type handler_type, DeprecatedString const& executable) const
+Handler Launcher::get_handler_for_executable(Handler::Type handler_type, ByteString const& executable) const
 {
     Handler handler;
     auto existing_handler = m_handlers.get(executable);
@@ -230,13 +230,13 @@ Handler Launcher::get_handler_for_executable(Handler::Type handler_type, Depreca
     return handler;
 }
 
-bool Launcher::open_with_user_preferences(HashMap<DeprecatedString, DeprecatedString> const& user_preferences, DeprecatedString const& key, Vector<DeprecatedString> const& arguments, DeprecatedString const& default_program)
+bool Launcher::open_with_user_preferences(HashMap<ByteString, ByteString> const& user_preferences, ByteString const& key, Vector<ByteString> const& arguments, ByteString const& default_program)
 {
     auto program_path = user_preferences.get(key);
     if (program_path.has_value())
         return spawn(program_path.value(), arguments);
 
-    DeprecatedString executable = "";
+    ByteString executable = "";
     if (for_each_handler(key, user_preferences, [&](auto const& handler) -> bool {
             if (executable.is_empty() && (handler.mime_types.contains(key) || handler.file_types.contains(key) || handler.protocols.contains(key))) {
                 executable = handler.executable;
@@ -259,7 +259,7 @@ bool Launcher::open_with_user_preferences(HashMap<DeprecatedString, DeprecatedSt
     return false;
 }
 
-size_t Launcher::for_each_handler(DeprecatedString const& key, HashMap<DeprecatedString, DeprecatedString> const& user_preference, Function<bool(Handler const&)> f)
+size_t Launcher::for_each_handler(ByteString const& key, HashMap<ByteString, ByteString> const& user_preference, Function<bool(Handler const&)> f)
 {
     auto user_preferred = user_preference.get(key);
     if (user_preferred.has_value())
@@ -282,7 +282,7 @@ size_t Launcher::for_each_handler(DeprecatedString const& key, HashMap<Deprecate
     return counted;
 }
 
-void Launcher::for_each_handler_for_path(DeprecatedString const& path, Function<bool(Handler const&)> f)
+void Launcher::for_each_handler_for_path(ByteString const& path, Function<bool(Handler const&)> f)
 {
     struct stat st;
     if (lstat(path.characters(), &st) < 0) {
@@ -309,7 +309,7 @@ void Launcher::for_each_handler_for_path(DeprecatedString const& path, Function<
             return;
         }
 
-        auto link_target = LexicalPath { link_target_or_error.release_value().to_deprecated_string() };
+        auto link_target = LexicalPath { link_target_or_error.release_value().to_byte_string() };
         LexicalPath absolute_link_target = link_target.is_absolute() ? link_target : LexicalPath::join(LexicalPath::dirname(path), link_target.string());
         auto real_path_or_error = FileSystem::real_path(absolute_link_target.string());
         if (real_path_or_error.is_error()) {
@@ -318,7 +318,7 @@ void Launcher::for_each_handler_for_path(DeprecatedString const& path, Function<
         }
         auto real_path = real_path_or_error.release_value();
 
-        return for_each_handler_for_path(real_path.to_deprecated_string(), [&](auto const& handler) -> bool {
+        return for_each_handler_for_path(real_path.to_byte_string(), [&](auto const& handler) -> bool {
             return f(handler);
         });
     }
@@ -356,13 +356,13 @@ bool Launcher::open_file_url(const URL& url)
     }
 
     if (S_ISDIR(st.st_mode)) {
-        Vector<DeprecatedString> fm_arguments;
+        Vector<ByteString> fm_arguments;
         if (!url.fragment().has_value() || url.fragment()->is_empty()) {
             fm_arguments.append(file_path);
         } else {
             fm_arguments.append("-s");
             fm_arguments.append("-r");
-            fm_arguments.append(DeprecatedString::formatted("{}/{}", file_path, *url.fragment()));
+            fm_arguments.append(ByteString::formatted("{}/{}", file_path, *url.fragment()));
         }
 
         auto handler_optional = m_file_handlers.get("directory");
@@ -385,13 +385,13 @@ bool Launcher::open_file_url(const URL& url)
         mime_type_or_extension = mime_type.value();
 
     auto handler_optional = m_file_handlers.get("txt");
-    DeprecatedString default_handler = "";
+    ByteString default_handler = "";
     if (handler_optional.has_value())
         default_handler = handler_optional.value();
 
     // Additional parameters parsing, specific for the file protocol and txt file handlers
-    Vector<DeprecatedString> additional_parameters;
-    DeprecatedString filepath = url.serialize_path();
+    Vector<ByteString> additional_parameters;
+    ByteString filepath = url.serialize_path();
 
     if (url.query().has_value()) {
         url.query()->bytes_as_string_view().for_each_split_view('&', SplitBehavior::Nothing, [&](auto parameter) {
@@ -400,7 +400,7 @@ bool Launcher::open_file_url(const URL& url)
                 auto line = pair[1].to_int();
                 if (line.has_value())
                     // TextEditor uses file:line:col to open a file at a specific line number
-                    filepath = DeprecatedString::formatted("{}:{}", filepath, line.value());
+                    filepath = ByteString::formatted("{}:{}", filepath, line.value());
             }
         });
     }
diff --git a/Userland/Services/LaunchServer/Launcher.h b/Userland/Services/LaunchServer/Launcher.h
index 260d8bb5ec0..4a313fb96f0 100644
--- a/Userland/Services/LaunchServer/Launcher.h
+++ b/Userland/Services/LaunchServer/Launcher.h
@@ -22,15 +22,15 @@ struct Handler {
         UserDefault
     };
     Type handler_type;
-    DeprecatedString name;
-    DeprecatedString executable;
-    HashTable<DeprecatedString> mime_types {};
-    HashTable<DeprecatedString> file_types {};
-    HashTable<DeprecatedString> protocols {};
+    ByteString name;
+    ByteString executable;
+    HashTable<ByteString> mime_types {};
+    HashTable<ByteString> file_types {};
+    HashTable<ByteString> protocols {};
 
-    static DeprecatedString name_from_executable(StringView);
-    void from_executable(Type, DeprecatedString const&);
-    DeprecatedString to_details_str() const;
+    static ByteString name_from_executable(StringView);
+    void from_executable(Type, ByteString const&);
+    ByteString to_details_str() const;
 };
 
 class Launcher {
@@ -38,25 +38,25 @@ public:
     Launcher();
     static Launcher& the();
 
-    void load_handlers(DeprecatedString const& af_dir = Desktop::AppFile::APP_FILES_DIRECTORY);
+    void load_handlers(ByteString const& af_dir = Desktop::AppFile::APP_FILES_DIRECTORY);
     void load_config(Core::ConfigFile const&);
-    bool open_url(const URL&, DeprecatedString const& handler_name);
-    Vector<DeprecatedString> handlers_for_url(const URL&);
-    Vector<DeprecatedString> handlers_with_details_for_url(const URL&);
+    bool open_url(const URL&, ByteString const& handler_name);
+    Vector<ByteString> handlers_for_url(const URL&);
+    Vector<ByteString> handlers_with_details_for_url(const URL&);
 
 private:
-    HashMap<DeprecatedString, Handler> m_handlers;
-    HashMap<DeprecatedString, DeprecatedString> m_protocol_handlers;
-    HashMap<DeprecatedString, DeprecatedString> m_file_handlers;
-    HashMap<DeprecatedString, DeprecatedString> m_mime_handlers;
+    HashMap<ByteString, Handler> m_handlers;
+    HashMap<ByteString, ByteString> m_protocol_handlers;
+    HashMap<ByteString, ByteString> m_file_handlers;
+    HashMap<ByteString, ByteString> m_mime_handlers;
 
-    bool has_mime_handlers(DeprecatedString const&);
-    Optional<StringView> mime_type_for_file(DeprecatedString path);
-    Handler get_handler_for_executable(Handler::Type, DeprecatedString const&) const;
-    size_t for_each_handler(DeprecatedString const& key, HashMap<DeprecatedString, DeprecatedString> const& user_preferences, Function<bool(Handler const&)> f);
-    void for_each_handler_for_path(DeprecatedString const&, Function<bool(Handler const&)> f);
+    bool has_mime_handlers(ByteString const&);
+    Optional<StringView> mime_type_for_file(ByteString path);
+    Handler get_handler_for_executable(Handler::Type, ByteString const&) const;
+    size_t for_each_handler(ByteString const& key, HashMap<ByteString, ByteString> const& user_preferences, Function<bool(Handler const&)> f);
+    void for_each_handler_for_path(ByteString const&, Function<bool(Handler const&)> f);
     bool open_file_url(const URL&);
-    bool open_with_user_preferences(HashMap<DeprecatedString, DeprecatedString> const& user_preferences, DeprecatedString const& key, Vector<DeprecatedString> const& arguments, DeprecatedString const& default_program = {});
-    bool open_with_handler_name(const URL&, DeprecatedString const& handler_name);
+    bool open_with_user_preferences(HashMap<ByteString, ByteString> const& user_preferences, ByteString const& key, Vector<ByteString> const& arguments, ByteString const& default_program = {});
+    bool open_with_handler_name(const URL&, ByteString const& handler_name);
 };
 }
diff --git a/Userland/Services/LoginServer/LoginWindow.h b/Userland/Services/LoginServer/LoginWindow.h
index 688965c1542..2859999f522 100644
--- a/Userland/Services/LoginServer/LoginWindow.h
+++ b/Userland/Services/LoginServer/LoginWindow.h
@@ -20,10 +20,10 @@ public:
 
     Function<void()> on_submit;
 
-    DeprecatedString username() const { return m_username->text(); }
+    ByteString username() const { return m_username->text(); }
     void set_username(StringView username) { m_username->set_text(username); }
 
-    DeprecatedString password() const { return m_password->text(); }
+    ByteString password() const { return m_password->text(); }
     void set_password(StringView password) { m_password->set_text(password); }
 
     void set_fail_message(StringView message) { m_fail_message->set_text(String::from_utf8(message).release_value_but_fixme_should_propagate_errors()); }
diff --git a/Userland/Services/LookupServer/ConnectionFromClient.cpp b/Userland/Services/LookupServer/ConnectionFromClient.cpp
index 68dafb8538c..a162c5e93ab 100644
--- a/Userland/Services/LookupServer/ConnectionFromClient.cpp
+++ b/Userland/Services/LookupServer/ConnectionFromClient.cpp
@@ -26,7 +26,7 @@ void ConnectionFromClient::die()
     s_connections.remove(client_id());
 }
 
-Messages::LookupServer::LookupNameResponse ConnectionFromClient::lookup_name(DeprecatedString const& name)
+Messages::LookupServer::LookupNameResponse ConnectionFromClient::lookup_name(ByteString const& name)
 {
     auto maybe_answers = LookupServer::the().lookup(name, RecordType::A);
     if (maybe_answers.is_error()) {
@@ -35,19 +35,19 @@ Messages::LookupServer::LookupNameResponse ConnectionFromClient::lookup_name(Dep
     }
 
     auto answers = maybe_answers.release_value();
-    Vector<DeprecatedString> addresses;
+    Vector<ByteString> addresses;
     for (auto& answer : answers) {
         addresses.append(answer.record_data());
     }
     return { 0, move(addresses) };
 }
 
-Messages::LookupServer::LookupAddressResponse ConnectionFromClient::lookup_address(DeprecatedString const& address)
+Messages::LookupServer::LookupAddressResponse ConnectionFromClient::lookup_address(ByteString const& address)
 {
     if (address.length() != 4)
-        return { 1, DeprecatedString() };
+        return { 1, ByteString() };
     IPv4Address ip_address { (u8 const*)address.characters() };
-    auto name = DeprecatedString::formatted("{}.{}.{}.{}.in-addr.arpa",
+    auto name = ByteString::formatted("{}.{}.{}.{}.in-addr.arpa",
         ip_address[3],
         ip_address[2],
         ip_address[1],
@@ -56,12 +56,12 @@ Messages::LookupServer::LookupAddressResponse ConnectionFromClient::lookup_addre
     auto maybe_answers = LookupServer::the().lookup(name, RecordType::PTR);
     if (maybe_answers.is_error()) {
         dbgln("LookupServer: Failed to lookup PTR record: {}", maybe_answers.error());
-        return { 1, DeprecatedString() };
+        return { 1, ByteString() };
     }
 
     auto answers = maybe_answers.release_value();
     if (answers.is_empty())
-        return { 1, DeprecatedString() };
+        return { 1, ByteString() };
     return { 0, answers[0].record_data() };
 }
 }
diff --git a/Userland/Services/LookupServer/ConnectionFromClient.h b/Userland/Services/LookupServer/ConnectionFromClient.h
index d5e4c458514..c3bc9d3a14d 100644
--- a/Userland/Services/LookupServer/ConnectionFromClient.h
+++ b/Userland/Services/LookupServer/ConnectionFromClient.h
@@ -25,8 +25,8 @@ public:
 private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>, int client_id);
 
-    virtual Messages::LookupServer::LookupNameResponse lookup_name(DeprecatedString const&) override;
-    virtual Messages::LookupServer::LookupAddressResponse lookup_address(DeprecatedString const&) override;
+    virtual Messages::LookupServer::LookupNameResponse lookup_name(ByteString const&) override;
+    virtual Messages::LookupServer::LookupAddressResponse lookup_address(ByteString const&) override;
 };
 
 }
diff --git a/Userland/Services/LookupServer/LookupServer.cpp b/Userland/Services/LookupServer/LookupServer.cpp
index 81570280f4d..b3945b91fb8 100644
--- a/Userland/Services/LookupServer/LookupServer.cpp
+++ b/Userland/Services/LookupServer/LookupServer.cpp
@@ -7,8 +7,8 @@
 #include "LookupServer.h"
 #include "ConnectionFromClient.h"
 #include <AK/BufferedStream.h>
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/HashMap.h>
 #include <AK/Random.h>
 #include <AK/StdLibExtras.h>
@@ -89,7 +89,7 @@ void LookupServer::load_etc_hosts()
 ErrorOr<HashMap<Name, Vector<Answer>, Name::Traits>> LookupServer::try_load_etc_hosts()
 {
     HashMap<Name, Vector<Answer>, Name::Traits> map;
-    auto add_answer = [&map](Name const& name, RecordType record_type, DeprecatedString data) -> ErrorOr<void> {
+    auto add_answer = [&map](Name const& name, RecordType record_type, ByteString data) -> ErrorOr<void> {
         // FIXME: Since try_ensure does not return a reference to the contained value, we have to
         // retrieve it separately. This is a try_ensure bug that should be fixed.
         TRY(map.try_ensure(name, []() { return Vector<Answer> {}; }));
@@ -132,18 +132,18 @@ ErrorOr<HashMap<Name, Vector<Answer>, Name::Traits>> LookupServer::try_load_etc_
         auto raw_addr = maybe_address->to_in_addr_t();
 
         Name name { fields[1] };
-        TRY(add_answer(name, RecordType::A, DeprecatedString { (char const*)&raw_addr, sizeof(raw_addr) }));
+        TRY(add_answer(name, RecordType::A, ByteString { (char const*)&raw_addr, sizeof(raw_addr) }));
 
         StringBuilder builder;
-        TRY(builder.try_append(maybe_address->to_deprecated_string_reversed()));
+        TRY(builder.try_append(maybe_address->to_byte_string_reversed()));
         TRY(builder.try_append(".in-addr.arpa"sv));
-        TRY(add_answer(builder.to_deprecated_string(), RecordType::PTR, name.as_string()));
+        TRY(add_answer(builder.to_byte_string(), RecordType::PTR, name.as_string()));
     }
 
     return map;
 }
 
-static DeprecatedString get_hostname()
+static ByteString get_hostname()
 {
     char buffer[_POSIX_HOST_NAME_MAX];
     VERIFY(gethostname(buffer, sizeof(buffer)) == 0);
@@ -182,7 +182,7 @@ ErrorOr<Vector<Answer>> LookupServer::lookup(Name const& name, RecordType record
     if (record_type == RecordType::A && get_hostname() == name) {
         IPv4Address address = { 127, 0, 0, 1 };
         auto raw_address = address.to_in_addr_t();
-        Answer answer { name, RecordType::A, RecordClass::IN, s_static_ttl, DeprecatedString { (char const*)&raw_address, sizeof(raw_address) }, false };
+        Answer answer { name, RecordType::A, RecordClass::IN, s_static_ttl, ByteString { (char const*)&raw_address, sizeof(raw_address) }, false };
         answers.append(move(answer));
         return answers;
     }
@@ -245,7 +245,7 @@ ErrorOr<Vector<Answer>> LookupServer::lookup(Name const& name, RecordType record
     return answers;
 }
 
-ErrorOr<Vector<Answer>> LookupServer::lookup(Name const& name, DeprecatedString const& nameserver, bool& did_get_response, RecordType record_type, ShouldRandomizeCase should_randomize_case)
+ErrorOr<Vector<Answer>> LookupServer::lookup(Name const& name, ByteString const& nameserver, bool& did_get_response, RecordType record_type, ShouldRandomizeCase should_randomize_case)
 {
     Packet request;
     request.set_is_query();
diff --git a/Userland/Services/LookupServer/LookupServer.h b/Userland/Services/LookupServer/LookupServer.h
index 4f197d0f324..88d70a616dc 100644
--- a/Userland/Services/LookupServer/LookupServer.h
+++ b/Userland/Services/LookupServer/LookupServer.h
@@ -33,12 +33,12 @@ private:
     void load_etc_hosts();
     void put_in_cache(Answer const&);
 
-    ErrorOr<Vector<Answer>> lookup(Name const& hostname, DeprecatedString const& nameserver, bool& did_get_response, RecordType record_type, ShouldRandomizeCase = ShouldRandomizeCase::Yes);
+    ErrorOr<Vector<Answer>> lookup(Name const& hostname, ByteString const& nameserver, bool& did_get_response, RecordType record_type, ShouldRandomizeCase = ShouldRandomizeCase::Yes);
 
     OwnPtr<IPC::MultiServer<ConnectionFromClient>> m_server;
     RefPtr<DNSServer> m_dns_server;
     RefPtr<MulticastDNS> m_mdns;
-    Vector<DeprecatedString> m_nameservers;
+    Vector<ByteString> m_nameservers;
     RefPtr<Core::FileWatcher> m_file_watcher;
     HashMap<Name, Vector<Answer>, Name::Traits> m_etc_hosts;
     HashMap<Name, Vector<Answer>, Name::Traits> m_lookup_cache;
diff --git a/Userland/Services/LookupServer/LookupServer.ipc b/Userland/Services/LookupServer/LookupServer.ipc
index e440a9072be..01b03a45a46 100644
--- a/Userland/Services/LookupServer/LookupServer.ipc
+++ b/Userland/Services/LookupServer/LookupServer.ipc
@@ -2,6 +2,6 @@
 endpoint LookupServer
 {
     // Keep these definitions synchronized with gethostbyname and gethostbyaddr in netdb.cpp
-    lookup_name(DeprecatedString name) => (int code, Vector<DeprecatedString> addresses)
-    lookup_address(DeprecatedString address) => (int code, DeprecatedString name)
+    lookup_name(ByteString name) => (int code, Vector<ByteString> addresses)
+    lookup_address(ByteString address) => (int code, ByteString name)
 }
diff --git a/Userland/Services/LookupServer/MulticastDNS.cpp b/Userland/Services/LookupServer/MulticastDNS.cpp
index ba8af23a96a..cb5ff0f49e2 100644
--- a/Userland/Services/LookupServer/MulticastDNS.cpp
+++ b/Userland/Services/LookupServer/MulticastDNS.cpp
@@ -6,7 +6,7 @@
  */
 
 #include "MulticastDNS.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/IPv4Address.h>
 #include <AK/JsonArray.h>
 #include <AK/JsonObject.h>
@@ -28,7 +28,7 @@ MulticastDNS::MulticastDNS(Core::EventReceiver* parent)
     if (gethostname(buffer, sizeof(buffer)) < 0) {
         perror("gethostname");
     } else {
-        m_hostname = DeprecatedString::formatted("{}.local", buffer);
+        m_hostname = ByteString::formatted("{}.local", buffer);
     }
 
     u8 zero = 0;
@@ -92,7 +92,7 @@ void MulticastDNS::announce()
             RecordType::A,
             RecordClass::IN,
             120,
-            DeprecatedString { (char const*)&raw_addr, sizeof(raw_addr) },
+            ByteString { (char const*)&raw_addr, sizeof(raw_addr) },
             true,
         };
         response.add_answer(answer);
@@ -133,7 +133,7 @@ Vector<IPv4Address> MulticastDNS::local_addresses() const
 
     json_or_error.value().as_array().for_each([&addresses](auto& value) {
         auto if_object = value.as_object();
-        auto address = if_object.get_deprecated_string("ipv4_address"sv).value_or({});
+        auto address = if_object.get_byte_string("ipv4_address"sv).value_or({});
         auto ipv4_address = IPv4Address::from_string(address);
         // Skip unconfigured interfaces.
         if (!ipv4_address.has_value())
diff --git a/Userland/Services/NetworkServer/main.cpp b/Userland/Services/NetworkServer/main.cpp
index 915ff8ea6b8..f212619ca84 100644
--- a/Userland/Services/NetworkServer/main.cpp
+++ b/Userland/Services/NetworkServer/main.cpp
@@ -42,15 +42,15 @@ ErrorOr<int> serenity_main(Main::Arguments)
     struct InterfaceConfig {
         bool enabled = false;
         bool dhcp_enabled = false;
-        DeprecatedString ipv4_address = "0.0.0.0"sv;
-        DeprecatedString ipv4_netmask = "0.0.0.0"sv;
-        DeprecatedString ipv4_gateway = "0.0.0.0"sv;
+        ByteString ipv4_address = "0.0.0.0"sv;
+        ByteString ipv4_netmask = "0.0.0.0"sv;
+        ByteString ipv4_gateway = "0.0.0.0"sv;
     };
 
-    Vector<DeprecatedString> interfaces_with_dhcp_enabled;
+    Vector<ByteString> interfaces_with_dhcp_enabled;
     proc_net_adapters_json.as_array().for_each([&](auto& value) {
         auto& if_object = value.as_object();
-        auto ifname = if_object.get_deprecated_string("name"sv).value_or({});
+        auto ifname = if_object.get_byte_string("name"sv).value_or({});
 
         if (ifname == "loop"sv)
             return;
diff --git a/Userland/Services/RequestServer/ConnectionCache.cpp b/Userland/Services/RequestServer/ConnectionCache.cpp
index 74a9b6a532d..6328a69bd2c 100644
--- a/Userland/Services/RequestServer/ConnectionCache.cpp
+++ b/Userland/Services/RequestServer/ConnectionCache.cpp
@@ -23,7 +23,7 @@ void request_did_finish(URL const& url, Core::Socket const* socket)
 
     dbgln_if(REQUESTSERVER_DEBUG, "Request for {} finished", url);
 
-    ConnectionKey partial_key { url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string(), url.port_or_default() };
+    ConnectionKey partial_key { url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string(), url.port_or_default() };
     auto fire_off_next_job = [&](auto& cache) {
         auto it = find_if(cache.begin(), cache.end(), [&](auto& connection) { return connection.key.hostname == partial_key.hostname && connection.key.port == partial_key.port; });
         if (it == cache.end()) {
diff --git a/Userland/Services/RequestServer/ConnectionCache.h b/Userland/Services/RequestServer/ConnectionCache.h
index 564b287731b..ecca5038302 100644
--- a/Userland/Services/RequestServer/ConnectionCache.h
+++ b/Userland/Services/RequestServer/ConnectionCache.h
@@ -37,14 +37,14 @@ struct Proxy {
     ErrorOr<NonnullOwnPtr<StorageType>> tunnel(URL const& url, Args&&... args)
     {
         if (data.type == Core::ProxyData::Direct) {
-            return TRY(SocketType::connect(url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string(), url.port_or_default(), forward<Args>(args)...));
+            return TRY(SocketType::connect(url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string(), url.port_or_default(), forward<Args>(args)...));
         }
         if (data.type == Core::ProxyData::SOCKS5) {
-            if constexpr (requires { SocketType::connect(declval<DeprecatedString>(), *proxy_client_storage, forward<Args>(args)...); }) {
-                proxy_client_storage = TRY(Core::SOCKSProxyClient::connect(data.host_ipv4, data.port, Core::SOCKSProxyClient::Version::V5, url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string(), url.port_or_default()));
-                return TRY(SocketType::connect(url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string(), *proxy_client_storage, forward<Args>(args)...));
+            if constexpr (requires { SocketType::connect(declval<ByteString>(), *proxy_client_storage, forward<Args>(args)...); }) {
+                proxy_client_storage = TRY(Core::SOCKSProxyClient::connect(data.host_ipv4, data.port, Core::SOCKSProxyClient::Version::V5, url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string(), url.port_or_default()));
+                return TRY(SocketType::connect(url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string(), *proxy_client_storage, forward<Args>(args)...));
             } else if constexpr (IsSame<SocketType, Core::TCPSocket>) {
-                return TRY(Core::SOCKSProxyClient::connect(data.host_ipv4, data.port, Core::SOCKSProxyClient::Version::V5, url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string(), url.port_or_default()));
+                return TRY(Core::SOCKSProxyClient::connect(data.host_ipv4, data.port, Core::SOCKSProxyClient::Version::V5, url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string(), url.port_or_default()));
             } else {
                 return Error::from_string_literal("SOCKS5 not supported for this socket type");
             }
@@ -101,7 +101,7 @@ struct Connection {
 };
 
 struct ConnectionKey {
-    DeprecatedString hostname;
+    ByteString hostname;
     u16 port { 0 };
     Core::ProxyData proxy_data {};
 
@@ -173,7 +173,7 @@ ErrorOr<void> recreate_socket_if_needed(T& connection, URL const& url)
 decltype(auto) get_or_create_connection(auto& cache, URL const& url, auto& job, Core::ProxyData proxy_data = {})
 {
     using CacheEntryType = RemoveCVReference<decltype(*cache.begin()->value)>;
-    auto& sockets_for_url = *cache.ensure({ url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string(), url.port_or_default(), proxy_data }, [] { return make<CacheEntryType>(); });
+    auto& sockets_for_url = *cache.ensure({ url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string(), url.port_or_default(), proxy_data }, [] { return make<CacheEntryType>(); });
 
     Proxy proxy { proxy_data };
 
diff --git a/Userland/Services/RequestServer/ConnectionFromClient.cpp b/Userland/Services/RequestServer/ConnectionFromClient.cpp
index a30e1c71b4a..aa3f9c05b11 100644
--- a/Userland/Services/RequestServer/ConnectionFromClient.cpp
+++ b/Userland/Services/RequestServer/ConnectionFromClient.cpp
@@ -30,19 +30,19 @@ void ConnectionFromClient::die()
         Core::EventLoop::current().quit(0);
 }
 
-Messages::RequestServer::IsSupportedProtocolResponse ConnectionFromClient::is_supported_protocol(DeprecatedString const& protocol)
+Messages::RequestServer::IsSupportedProtocolResponse ConnectionFromClient::is_supported_protocol(ByteString const& protocol)
 {
     bool supported = Protocol::find_by_name(protocol.to_lowercase());
     return supported;
 }
 
-Messages::RequestServer::StartRequestResponse ConnectionFromClient::start_request(DeprecatedString const& method, URL const& url, HashMap<DeprecatedString, DeprecatedString> const& request_headers, ByteBuffer const& request_body, Core::ProxyData const& proxy_data)
+Messages::RequestServer::StartRequestResponse ConnectionFromClient::start_request(ByteString const& method, URL const& url, HashMap<ByteString, ByteString> const& request_headers, ByteBuffer const& request_body, Core::ProxyData const& proxy_data)
 {
     if (!url.is_valid()) {
         dbgln("StartRequest: Invalid URL requested: '{}'", url);
         return { -1, Optional<IPC::File> {} };
     }
-    auto* protocol = Protocol::find_by_name(url.scheme().to_deprecated_string());
+    auto* protocol = Protocol::find_by_name(url.scheme().to_byte_string());
     if (!protocol) {
         dbgln("StartRequest: No protocol handler for URL: '{}'", url);
         return { -1, Optional<IPC::File> {} };
@@ -94,7 +94,7 @@ void ConnectionFromClient::did_request_certificates(Badge<Request>, Request& req
     async_certificate_requested(request.id());
 }
 
-Messages::RequestServer::SetCertificateResponse ConnectionFromClient::set_certificate(i32 request_id, DeprecatedString const& certificate, DeprecatedString const& key)
+Messages::RequestServer::SetCertificateResponse ConnectionFromClient::set_certificate(i32 request_id, ByteString const& certificate, ByteString const& key)
 {
     auto* request = const_cast<Request*>(m_requests.get(request_id).value_or(nullptr));
     bool success = false;
@@ -147,7 +147,7 @@ void ConnectionFromClient::ensure_connection(URL const& url, ::RequestServer::Ca
     }
 
     if (cache_level == CacheLevel::ResolveOnly) {
-        return Core::deferred_invoke([host = url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string()] {
+        return Core::deferred_invoke([host = url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string()] {
             dbgln("EnsureConnection: DNS-preload for {}", host);
             (void)gethostbyname(host.characters());
         });
@@ -156,7 +156,7 @@ void ConnectionFromClient::ensure_connection(URL const& url, ::RequestServer::Ca
     auto& job = Job::ensure(url);
     dbgln("EnsureConnection: Pre-connect to {}", url);
     auto do_preconnect = [&](auto& cache) {
-        auto serialized_host = url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string();
+        auto serialized_host = url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string();
         auto it = cache.find({ serialized_host, url.port_or_default() });
         if (it == cache.end() || it->value->is_empty())
             ConnectionCache::get_or_create_connection(cache, url, job);
diff --git a/Userland/Services/RequestServer/ConnectionFromClient.h b/Userland/Services/RequestServer/ConnectionFromClient.h
index 3724688f63a..144ace1f987 100644
--- a/Userland/Services/RequestServer/ConnectionFromClient.h
+++ b/Userland/Services/RequestServer/ConnectionFromClient.h
@@ -31,10 +31,10 @@ public:
 private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>);
 
-    virtual Messages::RequestServer::IsSupportedProtocolResponse is_supported_protocol(DeprecatedString const&) override;
-    virtual Messages::RequestServer::StartRequestResponse start_request(DeprecatedString const&, URL const&, HashMap<DeprecatedString, DeprecatedString> const&, ByteBuffer const&, Core::ProxyData const&) override;
+    virtual Messages::RequestServer::IsSupportedProtocolResponse is_supported_protocol(ByteString const&) override;
+    virtual Messages::RequestServer::StartRequestResponse start_request(ByteString const&, URL const&, HashMap<ByteString, ByteString> const&, ByteBuffer const&, Core::ProxyData const&) override;
     virtual Messages::RequestServer::StopRequestResponse stop_request(i32) override;
-    virtual Messages::RequestServer::SetCertificateResponse set_certificate(i32, DeprecatedString const&, DeprecatedString const&) override;
+    virtual Messages::RequestServer::SetCertificateResponse set_certificate(i32, ByteString const&, ByteString const&) override;
     virtual void ensure_connection(URL const& url, ::RequestServer::CacheLevel const& cache_level) override;
 
     HashMap<i32, OwnPtr<Request>> m_requests;
diff --git a/Userland/Services/RequestServer/GeminiProtocol.cpp b/Userland/Services/RequestServer/GeminiProtocol.cpp
index 642f24d6130..21fe5a5e49f 100644
--- a/Userland/Services/RequestServer/GeminiProtocol.cpp
+++ b/Userland/Services/RequestServer/GeminiProtocol.cpp
@@ -17,7 +17,7 @@ GeminiProtocol::GeminiProtocol()
 {
 }
 
-OwnPtr<Request> GeminiProtocol::start_request(ConnectionFromClient& client, DeprecatedString const&, const URL& url, HashMap<DeprecatedString, DeprecatedString> const&, ReadonlyBytes, Core::ProxyData proxy_data)
+OwnPtr<Request> GeminiProtocol::start_request(ConnectionFromClient& client, ByteString const&, const URL& url, HashMap<ByteString, ByteString> const&, ReadonlyBytes, Core::ProxyData proxy_data)
 {
     Gemini::GeminiRequest request;
     request.set_url(url);
diff --git a/Userland/Services/RequestServer/GeminiProtocol.h b/Userland/Services/RequestServer/GeminiProtocol.h
index 73b8c552788..30b6e2ac5b8 100644
--- a/Userland/Services/RequestServer/GeminiProtocol.h
+++ b/Userland/Services/RequestServer/GeminiProtocol.h
@@ -15,7 +15,7 @@ public:
     GeminiProtocol();
     virtual ~GeminiProtocol() override = default;
 
-    virtual OwnPtr<Request> start_request(ConnectionFromClient&, DeprecatedString const& method, const URL&, HashMap<DeprecatedString, DeprecatedString> const&, ReadonlyBytes body, Core::ProxyData proxy_data = {}) override;
+    virtual OwnPtr<Request> start_request(ConnectionFromClient&, ByteString const& method, const URL&, HashMap<ByteString, ByteString> const&, ReadonlyBytes body, Core::ProxyData proxy_data = {}) override;
 };
 
 }
diff --git a/Userland/Services/RequestServer/GeminiRequest.cpp b/Userland/Services/RequestServer/GeminiRequest.cpp
index f1a16575da4..48725b6e900 100644
--- a/Userland/Services/RequestServer/GeminiRequest.cpp
+++ b/Userland/Services/RequestServer/GeminiRequest.cpp
@@ -23,7 +23,7 @@ GeminiRequest::GeminiRequest(ConnectionFromClient& client, NonnullRefPtr<Gemini:
         if (auto* response = m_job->response()) {
             set_downloaded_size(MUST(m_job->response_length()));
             if (!response->meta().is_empty()) {
-                HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> headers;
+                HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> headers;
                 headers.set("meta", response->meta());
                 // Note: We're setting content-type to meta only on status==SUCCESS
                 //       we should perhaps have a better mechanism for this, since we
@@ -46,7 +46,7 @@ GeminiRequest::GeminiRequest(ConnectionFromClient& client, NonnullRefPtr<Gemini:
     };
 }
 
-void GeminiRequest::set_certificate(DeprecatedString, DeprecatedString)
+void GeminiRequest::set_certificate(ByteString, ByteString)
 {
 }
 
diff --git a/Userland/Services/RequestServer/GeminiRequest.h b/Userland/Services/RequestServer/GeminiRequest.h
index 5943f62c8b0..a8d9a4bdfb2 100644
--- a/Userland/Services/RequestServer/GeminiRequest.h
+++ b/Userland/Services/RequestServer/GeminiRequest.h
@@ -25,7 +25,7 @@ public:
 private:
     explicit GeminiRequest(ConnectionFromClient&, NonnullRefPtr<Gemini::Job>, NonnullOwnPtr<Core::File>&&);
 
-    virtual void set_certificate(DeprecatedString certificate, DeprecatedString key) override;
+    virtual void set_certificate(ByteString certificate, ByteString key) override;
 
     NonnullRefPtr<Gemini::Job> m_job;
 };
diff --git a/Userland/Services/RequestServer/HttpCommon.h b/Userland/Services/RequestServer/HttpCommon.h
index e5fdd6fa494..aa5a95c4cae 100644
--- a/Userland/Services/RequestServer/HttpCommon.h
+++ b/Userland/Services/RequestServer/HttpCommon.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/Optional.h>
@@ -61,7 +61,7 @@ void init(TSelf* self, TJob job)
 }
 
 template<typename TBadgedProtocol, typename TPipeResult>
-OwnPtr<Request> start_request(TBadgedProtocol&& protocol, ConnectionFromClient& client, DeprecatedString const& method, const URL& url, HashMap<DeprecatedString, DeprecatedString> const& headers, ReadonlyBytes body, TPipeResult&& pipe_result, Core::ProxyData proxy_data = {})
+OwnPtr<Request> start_request(TBadgedProtocol&& protocol, ConnectionFromClient& client, ByteString const& method, const URL& url, HashMap<ByteString, ByteString> const& headers, ReadonlyBytes body, TPipeResult&& pipe_result, Core::ProxyData proxy_data = {})
 {
     using TJob = typename TBadgedProtocol::Type::JobType;
     using TRequest = typename TBadgedProtocol::Type::RequestType;
diff --git a/Userland/Services/RequestServer/HttpProtocol.cpp b/Userland/Services/RequestServer/HttpProtocol.cpp
index 9a18ba743b4..a1480499970 100644
--- a/Userland/Services/RequestServer/HttpProtocol.cpp
+++ b/Userland/Services/RequestServer/HttpProtocol.cpp
@@ -6,7 +6,7 @@
 
 #include <AK/Badge.h>
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/URL.h>
@@ -22,7 +22,7 @@ HttpProtocol::HttpProtocol()
 {
 }
 
-OwnPtr<Request> HttpProtocol::start_request(ConnectionFromClient& client, DeprecatedString const& method, const URL& url, HashMap<DeprecatedString, DeprecatedString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data)
+OwnPtr<Request> HttpProtocol::start_request(ConnectionFromClient& client, ByteString const& method, const URL& url, HashMap<ByteString, ByteString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data)
 {
     return Detail::start_request(Badge<HttpProtocol> {}, client, method, url, headers, body, get_pipe_for_request(), proxy_data);
 }
diff --git a/Userland/Services/RequestServer/HttpProtocol.h b/Userland/Services/RequestServer/HttpProtocol.h
index 5e89e3db652..212087ac4f7 100644
--- a/Userland/Services/RequestServer/HttpProtocol.h
+++ b/Userland/Services/RequestServer/HttpProtocol.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/URL.h>
@@ -27,7 +27,7 @@ public:
     HttpProtocol();
     ~HttpProtocol() override = default;
 
-    virtual OwnPtr<Request> start_request(ConnectionFromClient&, DeprecatedString const& method, const URL&, HashMap<DeprecatedString, DeprecatedString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data = {}) override;
+    virtual OwnPtr<Request> start_request(ConnectionFromClient&, ByteString const& method, const URL&, HashMap<ByteString, ByteString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data = {}) override;
 };
 
 }
diff --git a/Userland/Services/RequestServer/HttpsProtocol.cpp b/Userland/Services/RequestServer/HttpsProtocol.cpp
index d3d7fab2b6e..6d9ea5a5311 100644
--- a/Userland/Services/RequestServer/HttpsProtocol.cpp
+++ b/Userland/Services/RequestServer/HttpsProtocol.cpp
@@ -6,7 +6,7 @@
 
 #include <AK/Badge.h>
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/URL.h>
@@ -22,7 +22,7 @@ HttpsProtocol::HttpsProtocol()
 {
 }
 
-OwnPtr<Request> HttpsProtocol::start_request(ConnectionFromClient& client, DeprecatedString const& method, const URL& url, HashMap<DeprecatedString, DeprecatedString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data)
+OwnPtr<Request> HttpsProtocol::start_request(ConnectionFromClient& client, ByteString const& method, const URL& url, HashMap<ByteString, ByteString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data)
 {
     return Detail::start_request(Badge<HttpsProtocol> {}, client, method, url, headers, body, get_pipe_for_request(), proxy_data);
 }
diff --git a/Userland/Services/RequestServer/HttpsProtocol.h b/Userland/Services/RequestServer/HttpsProtocol.h
index e377ad8bde2..9199d396157 100644
--- a/Userland/Services/RequestServer/HttpsProtocol.h
+++ b/Userland/Services/RequestServer/HttpsProtocol.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/OwnPtr.h>
 #include <AK/URL.h>
@@ -27,7 +27,7 @@ public:
     HttpsProtocol();
     ~HttpsProtocol() override = default;
 
-    virtual OwnPtr<Request> start_request(ConnectionFromClient&, DeprecatedString const& method, const URL&, HashMap<DeprecatedString, DeprecatedString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data = {}) override;
+    virtual OwnPtr<Request> start_request(ConnectionFromClient&, ByteString const& method, const URL&, HashMap<ByteString, ByteString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data = {}) override;
 };
 
 }
diff --git a/Userland/Services/RequestServer/HttpsRequest.cpp b/Userland/Services/RequestServer/HttpsRequest.cpp
index f9c9ba0272c..914714ee6ed 100644
--- a/Userland/Services/RequestServer/HttpsRequest.cpp
+++ b/Userland/Services/RequestServer/HttpsRequest.cpp
@@ -18,7 +18,7 @@ HttpsRequest::HttpsRequest(ConnectionFromClient& client, NonnullRefPtr<HTTP::Htt
     Detail::init(this, job);
 }
 
-void HttpsRequest::set_certificate(DeprecatedString certificate, DeprecatedString key)
+void HttpsRequest::set_certificate(ByteString certificate, ByteString key)
 {
     m_job->set_certificate(move(certificate), move(key));
 }
diff --git a/Userland/Services/RequestServer/HttpsRequest.h b/Userland/Services/RequestServer/HttpsRequest.h
index 01eb3870cd9..8539836f91c 100644
--- a/Userland/Services/RequestServer/HttpsRequest.h
+++ b/Userland/Services/RequestServer/HttpsRequest.h
@@ -26,7 +26,7 @@ public:
 private:
     explicit HttpsRequest(ConnectionFromClient&, NonnullRefPtr<HTTP::HttpsJob>, NonnullOwnPtr<Core::File>&&);
 
-    virtual void set_certificate(DeprecatedString certificate, DeprecatedString key) override;
+    virtual void set_certificate(ByteString certificate, ByteString key) override;
 
     NonnullRefPtr<HTTP::HttpsJob> m_job;
 };
diff --git a/Userland/Services/RequestServer/Protocol.cpp b/Userland/Services/RequestServer/Protocol.cpp
index 1f6630cfab9..a50496b8aa4 100644
--- a/Userland/Services/RequestServer/Protocol.cpp
+++ b/Userland/Services/RequestServer/Protocol.cpp
@@ -13,18 +13,18 @@
 
 namespace RequestServer {
 
-static HashMap<DeprecatedString, Protocol*>& all_protocols()
+static HashMap<ByteString, Protocol*>& all_protocols()
 {
-    static HashMap<DeprecatedString, Protocol*> map;
+    static HashMap<ByteString, Protocol*> map;
     return map;
 }
 
-Protocol* Protocol::find_by_name(DeprecatedString const& name)
+Protocol* Protocol::find_by_name(ByteString const& name)
 {
     return all_protocols().get(name).value_or(nullptr);
 }
 
-Protocol::Protocol(DeprecatedString const& name)
+Protocol::Protocol(ByteString const& name)
 {
     all_protocols().set(name, this);
 }
diff --git a/Userland/Services/RequestServer/Protocol.h b/Userland/Services/RequestServer/Protocol.h
index f601fe5711c..a093d1c41df 100644
--- a/Userland/Services/RequestServer/Protocol.h
+++ b/Userland/Services/RequestServer/Protocol.h
@@ -17,13 +17,13 @@ class Protocol {
 public:
     virtual ~Protocol();
 
-    DeprecatedString const& name() const { return m_name; }
-    virtual OwnPtr<Request> start_request(ConnectionFromClient&, DeprecatedString const& method, const URL&, HashMap<DeprecatedString, DeprecatedString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data = {}) = 0;
+    ByteString const& name() const { return m_name; }
+    virtual OwnPtr<Request> start_request(ConnectionFromClient&, ByteString const& method, const URL&, HashMap<ByteString, ByteString> const& headers, ReadonlyBytes body, Core::ProxyData proxy_data = {}) = 0;
 
-    static Protocol* find_by_name(DeprecatedString const&);
+    static Protocol* find_by_name(ByteString const&);
 
 protected:
-    explicit Protocol(DeprecatedString const& name);
+    explicit Protocol(ByteString const& name);
     struct Pipe {
         int read_fd { -1 };
         int write_fd { -1 };
@@ -31,7 +31,7 @@ protected:
     static ErrorOr<Pipe> get_pipe_for_request();
 
 private:
-    DeprecatedString m_name;
+    ByteString m_name;
 };
 
 }
diff --git a/Userland/Services/RequestServer/Request.cpp b/Userland/Services/RequestServer/Request.cpp
index 70824b1497a..f549b59b18c 100644
--- a/Userland/Services/RequestServer/Request.cpp
+++ b/Userland/Services/RequestServer/Request.cpp
@@ -24,13 +24,13 @@ void Request::stop()
     m_client.did_finish_request({}, *this, false);
 }
 
-void Request::set_response_headers(HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers)
+void Request::set_response_headers(HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers)
 {
     m_response_headers = response_headers;
     m_client.did_receive_headers({}, *this);
 }
 
-void Request::set_certificate(DeprecatedString, DeprecatedString)
+void Request::set_certificate(ByteString, ByteString)
 {
 }
 
diff --git a/Userland/Services/RequestServer/Request.h b/Userland/Services/RequestServer/Request.h
index ef86e42e69b..41df486e85f 100644
--- a/Userland/Services/RequestServer/Request.h
+++ b/Userland/Services/RequestServer/Request.h
@@ -25,10 +25,10 @@ public:
     Optional<u32> status_code() const { return m_status_code; }
     Optional<u64> total_size() const { return m_total_size; }
     size_t downloaded_size() const { return m_downloaded_size; }
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const& response_headers() const { return m_response_headers; }
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const& response_headers() const { return m_response_headers; }
 
     void stop();
-    virtual void set_certificate(DeprecatedString, DeprecatedString);
+    virtual void set_certificate(ByteString, ByteString);
 
     // FIXME: Want Badge<Protocol>, but can't make one from HttpProtocol, etc.
     void set_request_fd(int fd) { m_request_fd = fd; }
@@ -38,7 +38,7 @@ public:
     void did_progress(Optional<u64> total_size, u64 downloaded_size);
     void set_status_code(u32 status_code) { m_status_code = status_code; }
     void did_request_certificates();
-    void set_response_headers(HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> const&);
+    void set_response_headers(HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> const&);
     void set_downloaded_size(size_t size) { m_downloaded_size = size; }
     Core::File const& output_stream() const { return *m_output_stream; }
 
@@ -53,7 +53,7 @@ private:
     Optional<u64> m_total_size {};
     size_t m_downloaded_size { 0 };
     NonnullOwnPtr<Core::File> m_output_stream;
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> m_response_headers;
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> m_response_headers;
 };
 
 }
diff --git a/Userland/Services/RequestServer/RequestClient.ipc b/Userland/Services/RequestServer/RequestClient.ipc
index a170af465cd..124abd933b1 100644
--- a/Userland/Services/RequestServer/RequestClient.ipc
+++ b/Userland/Services/RequestServer/RequestClient.ipc
@@ -4,7 +4,7 @@ endpoint RequestClient
 {
     request_progress(i32 request_id, Optional<u64> total_size, u64 downloaded_size) =|
     request_finished(i32 request_id, bool success, u64 total_size) =|
-    headers_became_available(i32 request_id, HashMap<DeprecatedString,DeprecatedString,CaseInsensitiveStringTraits> response_headers, Optional<u32> status_code) =|
+    headers_became_available(i32 request_id, HashMap<ByteString,ByteString,CaseInsensitiveStringTraits> response_headers, Optional<u32> status_code) =|
 
     // Certificate requests
     certificate_requested(i32 request_id) =|
diff --git a/Userland/Services/RequestServer/RequestServer.ipc b/Userland/Services/RequestServer/RequestServer.ipc
index c629495cde7..8c256682b53 100644
--- a/Userland/Services/RequestServer/RequestServer.ipc
+++ b/Userland/Services/RequestServer/RequestServer.ipc
@@ -4,11 +4,11 @@
 endpoint RequestServer
 {
     // Test if a specific protocol is supported, e.g "http"
-    is_supported_protocol(DeprecatedString protocol) => (bool supported)
+    is_supported_protocol(ByteString protocol) => (bool supported)
 
-    start_request(DeprecatedString method, URL url, HashMap<DeprecatedString,DeprecatedString> request_headers, ByteBuffer request_body, Core::ProxyData proxy_data) => (i32 request_id, Optional<IPC::File> response_fd)
+    start_request(ByteString method, URL url, HashMap<ByteString,ByteString> request_headers, ByteBuffer request_body, Core::ProxyData proxy_data) => (i32 request_id, Optional<IPC::File> response_fd)
     stop_request(i32 request_id) => (bool success)
-    set_certificate(i32 request_id, DeprecatedString certificate, DeprecatedString key) => (bool success)
+    set_certificate(i32 request_id, ByteString certificate, ByteString key) => (bool success)
 
     ensure_connection(URL url, ::RequestServer::CacheLevel cache_level) =|
 }
diff --git a/Userland/Services/SQLServer/ConnectionFromClient.cpp b/Userland/Services/SQLServer/ConnectionFromClient.cpp
index 80d5a85f475..426755d8fc9 100644
--- a/Userland/Services/SQLServer/ConnectionFromClient.cpp
+++ b/Userland/Services/SQLServer/ConnectionFromClient.cpp
@@ -23,14 +23,14 @@ RefPtr<ConnectionFromClient> ConnectionFromClient::client_connection_for(int cli
     return nullptr;
 }
 
-void ConnectionFromClient::set_database_path(DeprecatedString database_path)
+void ConnectionFromClient::set_database_path(ByteString database_path)
 {
     m_database_path = move(database_path);
 }
 
 ConnectionFromClient::ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket> socket, int client_id)
     : IPC::ConnectionFromClient<SQLClientEndpoint, SQLServerEndpoint>(*this, move(socket), client_id)
-    , m_database_path(DeprecatedString::formatted("{}/sql", Core::StandardPaths::data_directory()))
+    , m_database_path(ByteString::formatted("{}/sql", Core::StandardPaths::data_directory()))
 {
     s_connections.set(client_id, *this);
 }
@@ -43,7 +43,7 @@ void ConnectionFromClient::die()
         on_disconnect();
 }
 
-Messages::SQLServer::ConnectResponse ConnectionFromClient::connect(DeprecatedString const& database_name)
+Messages::SQLServer::ConnectResponse ConnectionFromClient::connect(ByteString const& database_name)
 {
     dbgln_if(SQLSERVER_DEBUG, "ConnectionFromClient::connect(database_name: {})", database_name);
 
@@ -62,7 +62,7 @@ void ConnectionFromClient::disconnect(SQL::ConnectionID connection_id)
         dbgln("Database connection has disappeared");
 }
 
-Messages::SQLServer::PrepareStatementResponse ConnectionFromClient::prepare_statement(SQL::ConnectionID connection_id, DeprecatedString const& sql)
+Messages::SQLServer::PrepareStatementResponse ConnectionFromClient::prepare_statement(SQL::ConnectionID connection_id, ByteString const& sql)
 {
     dbgln_if(SQLSERVER_DEBUG, "ConnectionFromClient::prepare_statement(connection_id: {}, sql: '{}')", connection_id, sql);
 
@@ -93,7 +93,7 @@ Messages::SQLServer::ExecuteStatementResponse ConnectionFromClient::execute_stat
     }
 
     dbgln_if(SQLSERVER_DEBUG, "Statement has disappeared");
-    async_execution_error(statement_id, -1, SQL::SQLErrorCode::StatementUnavailable, DeprecatedString::formatted("{}", statement_id));
+    async_execution_error(statement_id, -1, SQL::SQLErrorCode::StatementUnavailable, ByteString::formatted("{}", statement_id));
     return Optional<SQL::ExecutionID> {};
 }
 
diff --git a/Userland/Services/SQLServer/ConnectionFromClient.h b/Userland/Services/SQLServer/ConnectionFromClient.h
index cb353fa8403..c12c5b5b62a 100644
--- a/Userland/Services/SQLServer/ConnectionFromClient.h
+++ b/Userland/Services/SQLServer/ConnectionFromClient.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/Vector.h>
@@ -28,18 +28,18 @@ public:
 
     static RefPtr<ConnectionFromClient> client_connection_for(int client_id);
 
-    void set_database_path(DeprecatedString);
+    void set_database_path(ByteString);
     Function<void()> on_disconnect;
 
 private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>, int client_id);
 
-    virtual Messages::SQLServer::ConnectResponse connect(DeprecatedString const&) override;
-    virtual Messages::SQLServer::PrepareStatementResponse prepare_statement(SQL::ConnectionID, DeprecatedString const&) override;
+    virtual Messages::SQLServer::ConnectResponse connect(ByteString const&) override;
+    virtual Messages::SQLServer::PrepareStatementResponse prepare_statement(SQL::ConnectionID, ByteString const&) override;
     virtual Messages::SQLServer::ExecuteStatementResponse execute_statement(SQL::StatementID, Vector<SQL::Value> const& placeholder_values) override;
     virtual void disconnect(SQL::ConnectionID) override;
 
-    DeprecatedString m_database_path;
+    ByteString m_database_path;
 };
 
 }
diff --git a/Userland/Services/SQLServer/DatabaseConnection.cpp b/Userland/Services/SQLServer/DatabaseConnection.cpp
index 87e481cb28a..30f6ea75a4c 100644
--- a/Userland/Services/SQLServer/DatabaseConnection.cpp
+++ b/Userland/Services/SQLServer/DatabaseConnection.cpp
@@ -20,7 +20,7 @@ static ErrorOr<NonnullRefPtr<SQL::Database>> find_or_create_database(StringView
             return connection.value->database();
     }
 
-    auto database_file = DeprecatedString::formatted("{}/{}.db", database_path, database_name);
+    auto database_file = ByteString::formatted("{}/{}.db", database_path, database_name);
     return SQL::Database::create(move(database_file));
 }
 
@@ -32,7 +32,7 @@ RefPtr<DatabaseConnection> DatabaseConnection::connection_for(SQL::ConnectionID
     return nullptr;
 }
 
-ErrorOr<NonnullRefPtr<DatabaseConnection>> DatabaseConnection::create(StringView database_path, DeprecatedString database_name, int client_id)
+ErrorOr<NonnullRefPtr<DatabaseConnection>> DatabaseConnection::create(StringView database_path, ByteString database_name, int client_id)
 {
     if (LexicalPath path(database_name); (path.title() != database_name) || (path.dirname() != "."))
         return Error::from_string_view("Invalid database name"sv);
@@ -48,7 +48,7 @@ ErrorOr<NonnullRefPtr<DatabaseConnection>> DatabaseConnection::create(StringView
     return adopt_nonnull_ref_or_enomem(new (nothrow) DatabaseConnection(move(database), move(database_name), client_id));
 }
 
-DatabaseConnection::DatabaseConnection(NonnullRefPtr<SQL::Database> database, DeprecatedString database_name, int client_id)
+DatabaseConnection::DatabaseConnection(NonnullRefPtr<SQL::Database> database, ByteString database_name, int client_id)
     : m_database(move(database))
     , m_database_name(move(database_name))
     , m_connection_id(s_next_connection_id++)
diff --git a/Userland/Services/SQLServer/DatabaseConnection.h b/Userland/Services/SQLServer/DatabaseConnection.h
index 611a0255e34..cc483440055 100644
--- a/Userland/Services/SQLServer/DatabaseConnection.h
+++ b/Userland/Services/SQLServer/DatabaseConnection.h
@@ -17,7 +17,7 @@ namespace SQLServer {
 
 class DatabaseConnection final : public RefCounted<DatabaseConnection> {
 public:
-    static ErrorOr<NonnullRefPtr<DatabaseConnection>> create(StringView database_path, DeprecatedString database_name, int client_id);
+    static ErrorOr<NonnullRefPtr<DatabaseConnection>> create(StringView database_path, ByteString database_name, int client_id);
 
     static RefPtr<DatabaseConnection> connection_for(SQL::ConnectionID connection_id);
     SQL::ConnectionID connection_id() const { return m_connection_id; }
@@ -28,10 +28,10 @@ public:
     SQL::ResultOr<SQL::StatementID> prepare_statement(StringView sql);
 
 private:
-    DatabaseConnection(NonnullRefPtr<SQL::Database> database, DeprecatedString database_name, int client_id);
+    DatabaseConnection(NonnullRefPtr<SQL::Database> database, ByteString database_name, int client_id);
 
     NonnullRefPtr<SQL::Database> m_database;
-    DeprecatedString m_database_name;
+    ByteString m_database_name;
     SQL::ConnectionID m_connection_id { 0 };
     int m_client_id { 0 };
 };
diff --git a/Userland/Services/SQLServer/SQLClient.ipc b/Userland/Services/SQLServer/SQLClient.ipc
index 8f26f79e1f2..890a0f9f346 100644
--- a/Userland/Services/SQLServer/SQLClient.ipc
+++ b/Userland/Services/SQLServer/SQLClient.ipc
@@ -3,8 +3,8 @@
 
 endpoint SQLClient
 {
-    execution_success(u64 statement_id, u64 execution_id, Vector<DeprecatedString> column_names, bool has_results, size_t created, size_t updated, size_t deleted) =|
+    execution_success(u64 statement_id, u64 execution_id, Vector<ByteString> column_names, bool has_results, size_t created, size_t updated, size_t deleted) =|
     next_result(u64 statement_id, u64 execution_id, Vector<SQL::Value> row) =|
     results_exhausted(u64 statement_id, u64 execution_id, size_t total_rows) =|
-    execution_error(u64 statement_id, u64 execution_id, SQL::SQLErrorCode code, DeprecatedString message) =|
+    execution_error(u64 statement_id, u64 execution_id, SQL::SQLErrorCode code, ByteString message) =|
 }
diff --git a/Userland/Services/SQLServer/SQLServer.ipc b/Userland/Services/SQLServer/SQLServer.ipc
index 2a01ae22f6f..1ffa5380232 100644
--- a/Userland/Services/SQLServer/SQLServer.ipc
+++ b/Userland/Services/SQLServer/SQLServer.ipc
@@ -2,8 +2,8 @@
 
 endpoint SQLServer
 {
-    connect(DeprecatedString name) => (Optional<u64> connection_id)
-    prepare_statement(u64 connection_id, DeprecatedString statement) => (Optional<u64> statement_id)
+    connect(ByteString name) => (Optional<u64> connection_id)
+    prepare_statement(u64 connection_id, ByteString statement) => (Optional<u64> statement_id)
     execute_statement(u64 statement_id, Vector<SQL::Value> placeholder_values) => (Optional<u64> execution_id)
     disconnect(u64 connection_id) => ()
 }
diff --git a/Userland/Services/SQLServer/SQLStatement.cpp b/Userland/Services/SQLServer/SQLStatement.cpp
index 5c49efc62d2..287fab05e31 100644
--- a/Userland/Services/SQLServer/SQLStatement.cpp
+++ b/Userland/Services/SQLServer/SQLStatement.cpp
@@ -29,7 +29,7 @@ SQL::ResultOr<NonnullRefPtr<SQLStatement>> SQLStatement::create(DatabaseConnecti
     auto statement = parser.next_statement();
 
     if (parser.has_errors())
-        return SQL::Result { SQL::SQLCommand::Unknown, SQL::SQLErrorCode::SyntaxError, parser.errors()[0].to_deprecated_string() };
+        return SQL::Result { SQL::SQLCommand::Unknown, SQL::SQLErrorCode::SyntaxError, parser.errors()[0].to_byte_string() };
 
     return TRY(adopt_nonnull_ref_or_enomem(new (nothrow) SQLStatement(connection, move(statement))));
 }
diff --git a/Userland/Services/SQLServer/main.cpp b/Userland/Services/SQLServer/main.cpp
index 0c8f2c754b5..af45bd14366 100644
--- a/Userland/Services/SQLServer/main.cpp
+++ b/Userland/Services/SQLServer/main.cpp
@@ -16,7 +16,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
 {
     TRY(Core::System::pledge("stdio accept unix rpath wpath cpath"));
 
-    auto database_path = DeprecatedString::formatted("{}/sql", Core::StandardPaths::data_directory());
+    auto database_path = ByteString::formatted("{}/sql", Core::StandardPaths::data_directory());
     TRY(Core::Directory::create(database_path, Core::Directory::CreateDirectories::Yes));
 
     TRY(Core::System::unveil(database_path, "rwc"sv));
diff --git a/Userland/Services/SpiceAgent/FileTransferOperation.cpp b/Userland/Services/SpiceAgent/FileTransferOperation.cpp
index 44ba04f94bd..b1fde1134d5 100644
--- a/Userland/Services/SpiceAgent/FileTransferOperation.cpp
+++ b/Userland/Services/SpiceAgent/FileTransferOperation.cpp
@@ -71,7 +71,7 @@ ErrorOr<void> FileTransferOperation::complete_transfer(SpiceAgent& agent)
     // Open the file manager for the user :^)
     // FIXME: This currently opens a new window for each successful file transfer...
     //        Is there a way/can we make a way for it to highlight a new file in an already-open window?
-    Desktop::Launcher::open(URL::create_with_file_scheme(Core::StandardPaths::downloads_directory(), m_metadata.name.to_deprecated_string()));
+    Desktop::Launcher::open(URL::create_with_file_scheme(Core::StandardPaths::downloads_directory(), m_metadata.name.to_byte_string()));
 
     return {};
 }
diff --git a/Userland/Services/SpiceAgent/SpiceAgent.cpp b/Userland/Services/SpiceAgent/SpiceAgent.cpp
index 2abbbef4e37..bdd4ab630ab 100644
--- a/Userland/Services/SpiceAgent/SpiceAgent.cpp
+++ b/Userland/Services/SpiceAgent/SpiceAgent.cpp
@@ -42,7 +42,7 @@ ErrorOr<void> SpiceAgent::start()
     TRY(this->send_message(capabilities_message));
 
     GUI::Clipboard::the().on_change = [this](auto const& mime_type) {
-        auto result = this->on_clipboard_update(String::from_deprecated_string(mime_type).release_value_but_fixme_should_propagate_errors());
+        auto result = this->on_clipboard_update(String::from_byte_string(mime_type).release_value_but_fixme_should_propagate_errors());
         if (result.is_error()) {
             dbgln("Failed to inform the spice server of a clipboard update: {}", result.release_error());
         }
@@ -85,7 +85,7 @@ ErrorOr<void> SpiceAgent::send_clipboard_contents(ClipboardDataType data_type)
 
     // We have an exception for `image/x-serenityos`, where we treat it as a PNG when talking to the spice server.
     auto is_serenity_image = data_and_type.mime_type == "image/x-serenityos" && data_type == ClipboardDataType::PNG;
-    if (!is_serenity_image && requested_mime_type.to_deprecated_string() != data_and_type.mime_type) {
+    if (!is_serenity_image && requested_mime_type.to_byte_string() != data_and_type.mime_type) {
         // If the requested mime type doesn't match what's on the clipboard, we won't send anything back.
         return Error::from_string_literal("Requested mime type doesn't match the clipboard's contents!");
     }
@@ -255,8 +255,8 @@ ErrorOr<void> SpiceAgent::did_receive_clipboard_message(ClipboardMessage& messag
     case ClipboardDataType::TIFF: {
         auto mime_type = TRY(clipboard_data_type_to_mime_type(message.data_type()));
 
-        // FIXME: It should be trivial to make `try_create_for_raw_bytes` take a `StringView` instead of a direct `DeprecatedString`.
-        auto decoder = Gfx::ImageDecoder::try_create_for_raw_bytes(message.contents(), mime_type.to_deprecated_string());
+        // FIXME: It should be trivial to make `try_create_for_raw_bytes` take a `StringView` instead of a direct `ByteString`.
+        auto decoder = Gfx::ImageDecoder::try_create_for_raw_bytes(message.contents(), mime_type.to_byte_string());
         if (!decoder || (decoder->frame_count() == 0)) {
             return Error::from_string_literal("Failed to find a suitable decoder for a pasted image!");
         }
diff --git a/Userland/Services/SystemServer/Service.cpp b/Userland/Services/SystemServer/Service.cpp
index ed8cf83c231..12d98e0a1bf 100644
--- a/Userland/Services/SystemServer/Service.cpp
+++ b/Userland/Services/SystemServer/Service.cpp
@@ -287,7 +287,7 @@ Service::Service(Core::ConfigFile const& config, StringView name)
     VERIFY(config.has_group(name));
 
     set_name(name);
-    m_executable_path = config.read_entry(name, "Executable", DeprecatedString::formatted("/bin/{}", this->name()));
+    m_executable_path = config.read_entry(name, "Executable", ByteString::formatted("/bin/{}", this->name()));
     m_extra_arguments = config.read_entry(name, "Arguments");
     m_stdio_file_path = config.read_entry_optional(name, "StdIO");
 
@@ -321,12 +321,12 @@ Service::Service(Core::ConfigFile const& config, StringView name)
     m_multi_instance = config.read_bool_entry(name, "MultiInstance");
     m_accept_socket_connections = config.read_bool_entry(name, "AcceptSocketConnections");
 
-    DeprecatedString socket_entry = config.read_entry(name, "Socket");
-    DeprecatedString socket_permissions_entry = config.read_entry(name, "SocketPermissions", "0600");
+    ByteString socket_entry = config.read_entry(name, "Socket");
+    ByteString socket_permissions_entry = config.read_entry(name, "SocketPermissions", "0600");
 
     if (!socket_entry.is_empty()) {
-        Vector<DeprecatedString> socket_paths = socket_entry.split(',');
-        Vector<DeprecatedString> socket_perms = socket_permissions_entry.split(',');
+        Vector<ByteString> socket_paths = socket_entry.split(',');
+        Vector<ByteString> socket_perms = socket_permissions_entry.split(',');
         m_sockets.ensure_capacity(socket_paths.size());
 
         // Need i here to iterate along with all other vectors.
diff --git a/Userland/Services/SystemServer/Service.h b/Userland/Services/SystemServer/Service.h
index 93a423d1adc..f1c3f7650bf 100644
--- a/Userland/Services/SystemServer/Service.h
+++ b/Userland/Services/SystemServer/Service.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/RefPtr.h>
 #include <LibCore/Account.h>
 #include <LibCore/ElapsedTimer.h>
@@ -42,7 +42,7 @@ private:
     /// requested by a service.
     struct SocketDescriptor {
         /// The path of the socket.
-        DeprecatedString path;
+        ByteString path;
         /// File descriptor of the socket. -1 if the socket hasn't been opened.
         int fd { -1 };
         /// File permissions of the socket.
@@ -50,11 +50,11 @@ private:
     };
 
     // Path to the executable. By default this is /bin/{m_name}.
-    DeprecatedString m_executable_path;
+    ByteString m_executable_path;
     // Extra arguments, starting from argv[1], to pass when exec'ing.
-    DeprecatedString m_extra_arguments;
+    ByteString m_extra_arguments;
     // File path to open as stdio fds.
-    Optional<DeprecatedString> m_stdio_file_path;
+    Optional<ByteString> m_stdio_file_path;
     int m_priority { 1 };
     // Whether we should re-launch it if it exits.
     bool m_keep_alive { false };
@@ -65,15 +65,15 @@ private:
     // Whether we should only spawn this service once somebody connects to the socket.
     bool m_lazy;
     // The name of the user we should run this service as.
-    Optional<DeprecatedString> m_user;
+    Optional<ByteString> m_user;
     // The working directory in which to spawn the service.
-    Optional<DeprecatedString> m_working_directory;
+    Optional<ByteString> m_working_directory;
     // System modes in which to run this service. By default, this is the graphical mode.
-    Vector<DeprecatedString> m_system_modes;
+    Vector<ByteString> m_system_modes;
     // Whether several instances of this service can run at once.
     bool m_multi_instance { false };
     // Environment variables to pass to the service.
-    DeprecatedString m_environment;
+    ByteString m_environment;
     // Socket descriptors for this service.
     Vector<SocketDescriptor> m_sockets;
 
diff --git a/Userland/Services/SystemServer/main.cpp b/Userland/Services/SystemServer/main.cpp
index a35c944307d..0e4ad0fead9 100644
--- a/Userland/Services/SystemServer/main.cpp
+++ b/Userland/Services/SystemServer/main.cpp
@@ -35,7 +35,7 @@
 static constexpr StringView text_system_mode = "text"sv;
 static constexpr StringView selftest_system_mode = "self-test"sv;
 static constexpr StringView graphical_system_mode = "graphical"sv;
-DeprecatedString g_system_mode = graphical_system_mode;
+ByteString g_system_mode = graphical_system_mode;
 Vector<NonnullRefPtr<Service>> g_services;
 
 // NOTE: This handler ensures that the destructor of g_services is called.
@@ -91,7 +91,7 @@ static ErrorOr<void> determine_system_mode()
         // Continue and assume "text" mode.
         return {};
     }
-    DeprecatedString const system_mode = DeprecatedString::copy(system_mode_buf_or_error.value(), Chomp);
+    ByteString const system_mode = ByteString::copy(system_mode_buf_or_error.value(), Chomp);
 
     g_system_mode = system_mode;
     declare_text_mode_on_failure.disarm();
diff --git a/Userland/Services/Taskbar/ClockWidget.cpp b/Userland/Services/Taskbar/ClockWidget.cpp
index 74a396eda9c..559511db5c0 100644
--- a/Userland/Services/Taskbar/ClockWidget.cpp
+++ b/Userland/Services/Taskbar/ClockWidget.cpp
@@ -122,17 +122,17 @@ ClockWidget::ClockWidget()
     };
 }
 
-void ClockWidget::update_format(DeprecatedString const& format)
+void ClockWidget::update_format(ByteString const& format)
 {
     m_time_format = format;
-    m_time_width = font().width(Core::DateTime::create(122, 2, 22, 22, 22, 22).to_deprecated_string(format));
+    m_time_width = font().width(Core::DateTime::create(122, 2, 22, 22, 22, 22).to_byte_string(format));
     set_fixed_size(m_time_width + 20, 21);
 }
 
 void ClockWidget::paint_event(GUI::PaintEvent& event)
 {
     GUI::Frame::paint_event(event);
-    auto time_text = Core::DateTime::now().to_deprecated_string(m_time_format);
+    auto time_text = Core::DateTime::now().to_byte_string(m_time_format);
     GUI::Painter painter(*this);
     painter.add_clip_rect(frame_inner_rect());
 
diff --git a/Userland/Services/Taskbar/ClockWidget.h b/Userland/Services/Taskbar/ClockWidget.h
index 985b4b2e49a..9b702661ed6 100644
--- a/Userland/Services/Taskbar/ClockWidget.h
+++ b/Userland/Services/Taskbar/ClockWidget.h
@@ -24,7 +24,7 @@ class ClockWidget final : public GUI::Frame {
 public:
     virtual ~ClockWidget() override = default;
 
-    void update_format(DeprecatedString const&);
+    void update_format(ByteString const&);
 
 private:
     ClockWidget();
@@ -47,7 +47,7 @@ private:
 
     void update_selected_calendar_button();
 
-    DeprecatedString m_time_format;
+    ByteString m_time_format;
     RefPtr<GUI::Window> m_calendar_window;
     RefPtr<GUI::Calendar> m_calendar;
     RefPtr<GUI::Button> m_next_date;
diff --git a/Userland/Services/Taskbar/QuickLaunchWidget.cpp b/Userland/Services/Taskbar/QuickLaunchWidget.cpp
index c5400296e2e..cbeb33aa40f 100644
--- a/Userland/Services/Taskbar/QuickLaunchWidget.cpp
+++ b/Userland/Services/Taskbar/QuickLaunchWidget.cpp
@@ -27,22 +27,22 @@
 
 namespace Taskbar {
 
-static DeprecatedString sanitize_name(DeprecatedString const& name)
+static ByteString sanitize_name(ByteString const& name)
 {
     return name.replace(" "sv, ""sv).replace("="sv, ""sv);
 }
 
-static DeprecatedString entry_to_config_string(size_t index, NonnullOwnPtr<QuickLaunchEntry> const& entry)
+static ByteString entry_to_config_string(size_t index, NonnullOwnPtr<QuickLaunchEntry> const& entry)
 {
-    return DeprecatedString::formatted("{}:{}", index, entry->path());
+    return ByteString::formatted("{}:{}", index, entry->path());
 }
 
 OwnPtr<QuickLaunchEntry> QuickLaunchEntry::create_from_path(StringView path)
 {
     if (path.ends_with(".af"sv)) {
-        auto af_path = path.to_deprecated_string();
+        auto af_path = path.to_byte_string();
         if (!path.starts_with('/'))
-            af_path = DeprecatedString::formatted("{}/{}", Desktop::AppFile::APP_FILES_DIRECTORY, path);
+            af_path = ByteString::formatted("{}/{}", Desktop::AppFile::APP_FILES_DIRECTORY, path);
 
         return make<QuickLaunchEntryAppFile>(Desktop::AppFile::open(af_path));
     }
@@ -91,7 +91,7 @@ GUI::Icon QuickLaunchEntryExecutable::icon() const
     return GUI::FileIconProvider::icon_for_executable(m_path);
 }
 
-DeprecatedString QuickLaunchEntryExecutable::name() const
+ByteString QuickLaunchEntryExecutable::name() const
 {
     return LexicalPath { m_path }.basename();
 }
@@ -128,11 +128,11 @@ ErrorOr<bool> QuickLaunchWidget::add_from_pid(pid_t pid_to_add)
         if (pid != pid_to_add)
             continue;
 
-        auto executable = process_object.get_deprecated_string("executable"sv);
+        auto executable = process_object.get_byte_string("executable"sv);
         if (!executable.has_value())
             break;
 
-        auto maybe_name = process_object.get_deprecated_string("name"sv);
+        auto maybe_name = process_object.get_byte_string("name"sv);
         if (!maybe_name.has_value())
             break;
 
@@ -184,7 +184,7 @@ void QuickLaunchWidget::drop_event(GUI::DropEvent& event)
             if (entry) {
                 auto result = update_entry(entry->name(), entry.release_nonnull());
                 if (result.is_error())
-                    GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to add quick launch entry: {}", result.release_error()));
+                    GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to add quick launch entry: {}", result.release_error()));
             }
         }
     }
@@ -212,7 +212,7 @@ void QuickLaunchWidget::mousemove_event(GUI::MouseEvent& event)
             m_dragging = true;
 
         if (entry->is_hovered())
-            GUI::Application::the()->show_tooltip(String::from_deprecated_string(entry->name()).release_value_but_fixme_should_propagate_errors(), this);
+            GUI::Application::the()->show_tooltip(String::from_byte_string(entry->name()).release_value_but_fixme_should_propagate_errors(), this);
     });
 
     if (m_dragging)
@@ -228,7 +228,7 @@ void QuickLaunchWidget::mouseup_event(GUI::MouseEvent& event)
             auto result = entry->launch();
             if (result.is_error()) {
                 // FIXME: This message box is displayed in a weird position
-                GUI::MessageBox::show_error(window(), DeprecatedString::formatted("Failed to open quick launch entry: {}", result.release_error()));
+                GUI::MessageBox::show_error(window(), ByteString::formatted("Failed to open quick launch entry: {}", result.release_error()));
             }
         }
 
@@ -330,7 +330,7 @@ void QuickLaunchWidget::load_entries(bool save)
 {
     struct ConfigEntry {
         int index;
-        DeprecatedString path;
+        ByteString path;
     };
 
     Vector<ConfigEntry> config_entries;
@@ -386,7 +386,7 @@ void QuickLaunchWidget::add_entries(Vector<NonnullOwnPtr<QuickLaunchEntry>> entr
     repaint();
 }
 
-ErrorOr<void> QuickLaunchWidget::update_entry(DeprecatedString const& button_name, NonnullOwnPtr<QuickLaunchEntry> entry, bool save)
+ErrorOr<void> QuickLaunchWidget::update_entry(ByteString const& button_name, NonnullOwnPtr<QuickLaunchEntry> entry, bool save)
 {
     auto file_name_to_watch = entry->file_name_to_watch();
     if (!file_name_to_watch.is_empty()) {
@@ -446,7 +446,7 @@ void QuickLaunchWidget::set_or_insert_entry(NonnullOwnPtr<QuickLaunchEntry> entr
     m_entries.append(move(entry));
 }
 
-void QuickLaunchWidget::remove_entry(DeprecatedString const& name, bool save)
+void QuickLaunchWidget::remove_entry(ByteString const& name, bool save)
 {
     for (size_t i = 0; i < m_entries.size(); i++) {
         if (m_entries[i]->name() != name)
diff --git a/Userland/Services/Taskbar/QuickLaunchWidget.h b/Userland/Services/Taskbar/QuickLaunchWidget.h
index b05e86bd92e..8e4e8429ed2 100644
--- a/Userland/Services/Taskbar/QuickLaunchWidget.h
+++ b/Userland/Services/Taskbar/QuickLaunchWidget.h
@@ -25,10 +25,10 @@ public:
     virtual ~QuickLaunchEntry() = default;
     virtual ErrorOr<void> launch() const = 0;
     virtual GUI::Icon icon() const = 0;
-    virtual DeprecatedString name() const = 0;
-    virtual DeprecatedString file_name_to_watch() const = 0;
+    virtual ByteString name() const = 0;
+    virtual ByteString file_name_to_watch() const = 0;
 
-    virtual DeprecatedString path() = 0;
+    virtual ByteString path() = 0;
 
     bool is_hovered() const { return m_hovered; }
     void set_hovered(bool hovered) { m_hovered = hovered; }
@@ -50,10 +50,10 @@ public:
 
     virtual ErrorOr<void> launch() const override;
     virtual GUI::Icon icon() const override { return m_app_file->icon(); }
-    virtual DeprecatedString name() const override { return m_app_file->name(); }
-    virtual DeprecatedString file_name_to_watch() const override { return {}; }
+    virtual ByteString name() const override { return m_app_file->name(); }
+    virtual ByteString file_name_to_watch() const override { return {}; }
 
-    virtual DeprecatedString path() override { return m_app_file->filename(); }
+    virtual ByteString path() override { return m_app_file->filename(); }
 
 private:
     NonnullRefPtr<Desktop::AppFile> m_app_file;
@@ -61,37 +61,37 @@ private:
 
 class QuickLaunchEntryExecutable : public QuickLaunchEntry {
 public:
-    explicit QuickLaunchEntryExecutable(DeprecatedString path)
+    explicit QuickLaunchEntryExecutable(ByteString path)
         : m_path(move(path))
     {
     }
 
     virtual ErrorOr<void> launch() const override;
     virtual GUI::Icon icon() const override;
-    virtual DeprecatedString name() const override;
-    virtual DeprecatedString file_name_to_watch() const override { return m_path; }
+    virtual ByteString name() const override;
+    virtual ByteString file_name_to_watch() const override { return m_path; }
 
-    virtual DeprecatedString path() override { return m_path; }
+    virtual ByteString path() override { return m_path; }
 
 private:
-    DeprecatedString m_path;
+    ByteString m_path;
 };
 class QuickLaunchEntryFile : public QuickLaunchEntry {
 public:
-    explicit QuickLaunchEntryFile(DeprecatedString path)
+    explicit QuickLaunchEntryFile(ByteString path)
         : m_path(move(path))
     {
     }
 
     virtual ErrorOr<void> launch() const override;
     virtual GUI::Icon icon() const override;
-    virtual DeprecatedString name() const override { return m_path; }
-    virtual DeprecatedString file_name_to_watch() const override { return m_path; }
+    virtual ByteString name() const override { return m_path; }
+    virtual ByteString file_name_to_watch() const override { return m_path; }
 
-    virtual DeprecatedString path() override { return m_path; }
+    virtual ByteString path() override { return m_path; }
 
 private:
-    DeprecatedString m_path;
+    ByteString m_path;
 };
 
 class QuickLaunchWidget : public GUI::Frame
@@ -131,7 +131,7 @@ private:
     ErrorOr<void> create_context_menu();
 
     void load_entries(bool save = true);
-    ErrorOr<void> update_entry(DeprecatedString const&, NonnullOwnPtr<QuickLaunchEntry>, bool save = true);
+    ErrorOr<void> update_entry(ByteString const&, NonnullOwnPtr<QuickLaunchEntry>, bool save = true);
     void add_entries(Vector<NonnullOwnPtr<QuickLaunchEntry>> entries, bool save = true);
 
     template<typename Callback>
@@ -142,7 +142,7 @@ private:
     void repaint();
 
     void set_or_insert_entry(NonnullOwnPtr<QuickLaunchEntry>, bool save = true);
-    void remove_entry(DeprecatedString const&, bool save = true);
+    void remove_entry(ByteString const&, bool save = true);
     void recalculate_order();
 
     bool m_dragging { false };
@@ -151,7 +151,7 @@ private:
 
     RefPtr<GUI::Menu> m_context_menu;
     RefPtr<GUI::Action> m_context_menu_default_action;
-    DeprecatedString m_context_menu_app_name;
+    ByteString m_context_menu_app_name;
     RefPtr<Core::FileWatcher> m_watcher;
 
     Vector<NonnullOwnPtr<QuickLaunchEntry>> m_entries;
diff --git a/Userland/Services/Taskbar/ShutdownDialog.cpp b/Userland/Services/Taskbar/ShutdownDialog.cpp
index 9a0f2bc8ab5..b3c4775c3c5 100644
--- a/Userland/Services/Taskbar/ShutdownDialog.cpp
+++ b/Userland/Services/Taskbar/ShutdownDialog.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "ShutdownDialog.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <LibGUI/BoxLayout.h>
 #include <LibGUI/Button.h>
@@ -17,7 +17,7 @@
 #include <LibGfx/Font/FontDatabase.h>
 
 struct Option {
-    DeprecatedString title;
+    ByteString title;
     ShutdownDialog::Command command;
     bool enabled;
     bool default_action;
@@ -74,7 +74,7 @@ ShutdownDialog::ShutdownDialog()
         auto action = options[i];
         auto& radio = right_container.add<GUI::RadioButton>();
         radio.set_enabled(action.enabled);
-        radio.set_text(String::from_deprecated_string(action.title).release_value_but_fixme_should_propagate_errors());
+        radio.set_text(String::from_byte_string(action.title).release_value_but_fixme_should_propagate_errors());
 
         radio.on_checked = [this, i](auto) {
             m_selected_option = i;
diff --git a/Userland/Services/Taskbar/TaskbarWindow.cpp b/Userland/Services/Taskbar/TaskbarWindow.cpp
index 6d2bf71fc18..85aba4d7e57 100644
--- a/Userland/Services/Taskbar/TaskbarWindow.cpp
+++ b/Userland/Services/Taskbar/TaskbarWindow.cpp
@@ -200,8 +200,8 @@ void TaskbarWindow::update_window_button(::Window& window, bool show_as_active)
     auto* button = window.button();
     if (!button)
         return;
-    button->set_text(String::from_deprecated_string(window.title()).release_value_but_fixme_should_propagate_errors());
-    button->set_tooltip(String::from_deprecated_string(window.title()).release_value_but_fixme_should_propagate_errors());
+    button->set_text(String::from_byte_string(window.title()).release_value_but_fixme_should_propagate_errors());
+    button->set_tooltip(String::from_byte_string(window.title()).release_value_but_fixme_should_propagate_errors());
     button->set_checked(show_as_active);
     button->set_visible(is_window_on_current_workspace(window));
 }
diff --git a/Userland/Services/Taskbar/WindowList.h b/Userland/Services/Taskbar/WindowList.h
index 84b40253346..3d372bc1909 100644
--- a/Userland/Services/Taskbar/WindowList.h
+++ b/Userland/Services/Taskbar/WindowList.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include "WindowIdentifier.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <LibGUI/Button.h>
 #include <LibGfx/Rect.h>
@@ -27,8 +27,8 @@ public:
 
     WindowIdentifier const& identifier() const { return m_identifier; }
 
-    DeprecatedString title() const { return m_title; }
-    void set_title(DeprecatedString const& title) { m_title = title; }
+    ByteString title() const { return m_title; }
+    void set_title(ByteString const& title) { m_title = title; }
 
     Gfx::IntRect rect() const { return m_rect; }
     void set_rect(Gfx::IntRect const& rect) { m_rect = rect; }
@@ -68,7 +68,7 @@ public:
 
 private:
     WindowIdentifier m_identifier;
-    DeprecatedString m_title;
+    ByteString m_title;
     Gfx::IntRect m_rect;
     RefPtr<GUI::Button> m_button;
     RefPtr<Gfx::Bitmap> m_icon;
diff --git a/Userland/Services/Taskbar/main.cpp b/Userland/Services/Taskbar/main.cpp
index 32518d586b9..bb76a448b7d 100644
--- a/Userland/Services/Taskbar/main.cpp
+++ b/Userland/Services/Taskbar/main.cpp
@@ -35,7 +35,7 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
-static ErrorOr<Vector<DeprecatedString>> discover_apps_and_categories();
+static ErrorOr<Vector<ByteString>> discover_apps_and_categories();
 static ErrorOr<NonnullRefPtr<GUI::Menu>> build_system_menu(GUI::Window&);
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
@@ -76,10 +76,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 }
 
 struct AppMetadata {
-    DeprecatedString executable;
-    DeprecatedString name;
-    DeprecatedString category;
-    DeprecatedString working_directory;
+    ByteString executable;
+    ByteString name;
+    ByteString category;
+    ByteString working_directory;
     GUI::Icon icon;
     bool run_in_terminal;
     bool requires_root;
@@ -92,9 +92,9 @@ Vector<Gfx::SystemThemeMetaData> g_themes;
 RefPtr<GUI::Menu> g_themes_menu;
 GUI::ActionGroup g_themes_group;
 
-ErrorOr<Vector<DeprecatedString>> discover_apps_and_categories()
+ErrorOr<Vector<ByteString>> discover_apps_and_categories()
 {
-    HashTable<DeprecatedString> seen_app_categories;
+    HashTable<ByteString> seen_app_categories;
     Desktop::AppFile::for_each([&](auto af) {
         if (af->exclude_from_system_menu())
             return;
@@ -105,7 +105,7 @@ ErrorOr<Vector<DeprecatedString>> discover_apps_and_categories()
     });
     quick_sort(g_apps, [](auto& a, auto& b) { return a.name < b.name; });
 
-    Vector<DeprecatedString> sorted_app_categories;
+    Vector<ByteString> sorted_app_categories;
     TRY(sorted_app_categories.try_ensure_capacity(seen_app_categories.size()));
     for (auto const& category : seen_app_categories)
         sorted_app_categories.unchecked_append(category);
@@ -116,7 +116,7 @@ ErrorOr<Vector<DeprecatedString>> discover_apps_and_categories()
 
 ErrorOr<NonnullRefPtr<GUI::Menu>> build_system_menu(GUI::Window& window)
 {
-    Vector<DeprecatedString> const sorted_app_categories = TRY(discover_apps_and_categories());
+    Vector<ByteString> const sorted_app_categories = TRY(discover_apps_and_categories());
     auto system_menu = GUI::Menu::construct("\xE2\x9A\xA1"_string); // HIGH VOLTAGE SIGN
 
     system_menu->add_action(GUI::Action::create("&About SerenityOS", TRY(Gfx::Bitmap::load_from_file("/res/icons/16x16/ladyball.png"sv)), [&](auto&) {
@@ -127,13 +127,13 @@ ErrorOr<NonnullRefPtr<GUI::Menu>> build_system_menu(GUI::Window& window)
 
     // First we construct all the necessary app category submenus.
     auto category_icons = TRY(Core::ConfigFile::open("/res/icons/SystemMenu.ini"));
-    HashMap<DeprecatedString, NonnullRefPtr<GUI::Menu>> app_category_menus;
+    HashMap<ByteString, NonnullRefPtr<GUI::Menu>> app_category_menus;
 
-    Function<void(DeprecatedString const&)> create_category_menu;
-    create_category_menu = [&](DeprecatedString const& category) {
+    Function<void(ByteString const&)> create_category_menu;
+    create_category_menu = [&](ByteString const& category) {
         if (app_category_menus.contains(category))
             return;
-        DeprecatedString parent_category, child_category = category;
+        ByteString parent_category, child_category = category;
         for (ssize_t i = category.length() - 1; i >= 0; i--) {
             if (category[i] == '/') {
                 parent_category = category.substring(0, i);
@@ -151,7 +151,7 @@ ErrorOr<NonnullRefPtr<GUI::Menu>> build_system_menu(GUI::Window& window)
                 VERIFY(parent_menu);
             }
         }
-        auto category_menu = parent_menu->add_submenu(String::from_deprecated_string(child_category).release_value_but_fixme_should_propagate_errors());
+        auto category_menu = parent_menu->add_submenu(String::from_byte_string(child_category).release_value_but_fixme_should_propagate_errors());
         auto category_icon_path = category_icons->read_entry("16x16", category);
         if (!category_icon_path.is_empty()) {
             auto icon_or_error = Gfx::Bitmap::load_from_file(category_icon_path);
@@ -181,7 +181,7 @@ ErrorOr<NonnullRefPtr<GUI::Menu>> build_system_menu(GUI::Window& window)
             StringView executable;
             Vector<char const*, 2> arguments;
             // FIXME: These single quotes won't be enough for executables with single quotes in their name.
-            auto pls_with_executable = DeprecatedString::formatted("/bin/pls '{}'", app.executable);
+            auto pls_with_executable = ByteString::formatted("/bin/pls '{}'", app.executable);
             if (app.run_in_terminal && !app.requires_root) {
                 executable = "/bin/Terminal"sv;
                 arguments = { "-e", app.executable.characters() };
diff --git a/Userland/Services/TelnetServer/Command.h b/Userland/Services/TelnetServer/Command.h
index ce31d33b78f..afa14bc0bfd 100644
--- a/Userland/Services/TelnetServer/Command.h
+++ b/Userland/Services/TelnetServer/Command.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <AK/Types.h>
 
@@ -21,7 +21,7 @@ struct Command {
     u8 command;
     u8 subcommand;
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
         StringBuilder builder;
 
@@ -39,7 +39,7 @@ struct Command {
             builder.append("DONT"sv);
             break;
         default:
-            builder.append(DeprecatedString::formatted("UNKNOWN<{:02x}>", command));
+            builder.append(ByteString::formatted("UNKNOWN<{:02x}>", command));
             break;
         }
 
@@ -53,10 +53,10 @@ struct Command {
             builder.append("SUPPRESS_GO_AHEAD"sv);
             break;
         default:
-            builder.append(DeprecatedString::formatted("UNKNOWN<{:02x}>", subcommand));
+            builder.append(ByteString::formatted("UNKNOWN<{:02x}>", subcommand));
             break;
         }
 
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 };
diff --git a/Userland/Services/TelnetServer/main.cpp b/Userland/Services/TelnetServer/main.cpp
index d2b8620f5e6..379bc43ca55 100644
--- a/Userland/Services/TelnetServer/main.cpp
+++ b/Userland/Services/TelnetServer/main.cpp
@@ -5,7 +5,7 @@
  */
 
 #include "Client.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/Types.h>
 #include <LibCore/ArgsParser.h>
@@ -20,7 +20,7 @@
 #include <sys/ioctl.h>
 #include <unistd.h>
 
-static void run_command(int ptm_fd, DeprecatedString command)
+static void run_command(int ptm_fd, ByteString command)
 {
     pid_t pid = fork();
     if (pid == 0) {
diff --git a/Userland/Services/WebContent/ConnectionFromClient.cpp b/Userland/Services/WebContent/ConnectionFromClient.cpp
index 90b0c3d5cac..e4739f37279 100644
--- a/Userland/Services/WebContent/ConnectionFromClient.cpp
+++ b/Userland/Services/WebContent/ConnectionFromClient.cpp
@@ -86,7 +86,7 @@ void ConnectionFromClient::set_window_handle(String const& handle)
     page().page().top_level_browsing_context().set_window_handle(handle);
 }
 
-void ConnectionFromClient::connect_to_webdriver(DeprecatedString const& webdriver_ipc_path)
+void ConnectionFromClient::connect_to_webdriver(ByteString const& webdriver_ipc_path)
 {
     // FIXME: Propagate this error back to the browser.
     if (auto result = page().connect_to_webdriver(webdriver_ipc_path); result.is_error())
@@ -100,7 +100,7 @@ void ConnectionFromClient::update_system_theme(Core::AnonymousBuffer const& them
     page().set_palette_impl(*impl);
 }
 
-void ConnectionFromClient::update_system_fonts(DeprecatedString const& default_font_query, DeprecatedString const& fixed_width_font_query, DeprecatedString const& window_title_font_query)
+void ConnectionFromClient::update_system_fonts(ByteString const& default_font_query, ByteString const& fixed_width_font_query, ByteString const& window_title_font_query)
 {
     Gfx::FontDatabase::set_default_font_query(default_font_query);
     Gfx::FontDatabase::set_fixed_width_font_query(fixed_width_font_query);
@@ -117,11 +117,11 @@ void ConnectionFromClient::load_url(const URL& url)
     dbgln_if(SPAM_DEBUG, "handle: WebContentServer::LoadURL: url={}", url);
 
 #if defined(AK_OS_SERENITY)
-    DeprecatedString process_name;
+    ByteString process_name;
     if (url.host().has<Empty>() || url.host() == String {})
         process_name = "WebContent";
     else
-        process_name = DeprecatedString::formatted("WebContent: {}", url.serialized_host().release_value_but_fixme_should_propagate_errors());
+        process_name = ByteString::formatted("WebContent: {}", url.serialized_host().release_value_but_fixme_should_propagate_errors());
 
     pthread_setname_np(pthread_self(), process_name.characters());
 #endif
@@ -129,7 +129,7 @@ void ConnectionFromClient::load_url(const URL& url)
     page().page().load(url);
 }
 
-void ConnectionFromClient::load_html(DeprecatedString const& html)
+void ConnectionFromClient::load_html(ByteString const& html)
 {
     dbgln_if(SPAM_DEBUG, "handle: WebContentServer::LoadHTML: html={}", html);
     page().page().load_html(html);
@@ -364,7 +364,7 @@ void ConnectionFromClient::report_finished_handling_input_event(bool event_was_h
     async_did_finish_handling_input_event(event_was_handled);
 }
 
-void ConnectionFromClient::debug_request(DeprecatedString const& request, DeprecatedString const& argument)
+void ConnectionFromClient::debug_request(ByteString const& request, ByteString const& argument)
 {
     if (request == "dump-session-history") {
         auto const& traversable = page().page().top_level_traversable();
@@ -452,7 +452,7 @@ void ConnectionFromClient::debug_request(DeprecatedString const& request, Deprec
     }
 
     if (request == "spoof-user-agent") {
-        Web::ResourceLoader::the().set_user_agent(MUST(String::from_deprecated_string(argument)));
+        Web::ResourceLoader::the().set_user_agent(MUST(String::from_byte_string(argument)));
         return;
     }
 
@@ -496,14 +496,14 @@ void ConnectionFromClient::debug_request(DeprecatedString const& request, Deprec
 void ConnectionFromClient::get_source()
 {
     if (auto* doc = page().page().top_level_browsing_context().active_document()) {
-        async_did_get_source(doc->url(), doc->source().to_deprecated_string());
+        async_did_get_source(doc->url(), doc->source().to_byte_string());
     }
 }
 
 void ConnectionFromClient::inspect_dom_tree()
 {
     if (auto* doc = page().page().top_level_browsing_context().active_document()) {
-        async_did_get_dom_tree(doc->dump_dom_tree_as_json().to_deprecated_string());
+        async_did_get_dom_tree(doc->dump_dom_tree_as_json().to_byte_string());
     }
 }
 
@@ -531,19 +531,19 @@ Messages::WebContentServer::InspectDomNodeResponse ConnectionFromClient::inspect
         if (!element.computed_css_values())
             return { false, "", "", "", "", "" };
 
-        auto serialize_json = [](Web::CSS::StyleProperties const& properties) -> DeprecatedString {
+        auto serialize_json = [](Web::CSS::StyleProperties const& properties) -> ByteString {
             StringBuilder builder;
 
             auto serializer = MUST(JsonObjectSerializer<>::try_create(builder));
             properties.for_each_property([&](auto property_id, auto& value) {
-                MUST(serializer.add(Web::CSS::string_from_property_id(property_id), value.to_string().to_deprecated_string()));
+                MUST(serializer.add(Web::CSS::string_from_property_id(property_id), value.to_string().to_byte_string()));
             });
             MUST(serializer.finish());
 
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         };
 
-        auto serialize_custom_properties_json = [](Web::DOM::Element const& element, Optional<Web::CSS::Selector::PseudoElement::Type> pseudo_element) -> DeprecatedString {
+        auto serialize_custom_properties_json = [](Web::DOM::Element const& element, Optional<Web::CSS::Selector::PseudoElement::Type> pseudo_element) -> ByteString {
             StringBuilder builder;
             auto serializer = MUST(JsonObjectSerializer<>::try_create(builder));
             HashTable<FlyString> seen_properties;
@@ -562,9 +562,9 @@ Messages::WebContentServer::InspectDomNodeResponse ConnectionFromClient::inspect
 
             MUST(serializer.finish());
 
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         };
-        auto serialize_node_box_sizing_json = [](Web::Layout::Node const* layout_node) -> DeprecatedString {
+        auto serialize_node_box_sizing_json = [](Web::Layout::Node const* layout_node) -> ByteString {
             if (!layout_node || !layout_node->is_box()) {
                 return "{}";
             }
@@ -593,10 +593,10 @@ Messages::WebContentServer::InspectDomNodeResponse ConnectionFromClient::inspect
             }
 
             MUST(serializer.finish());
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         };
 
-        auto serialize_aria_properties_state_json = [](Web::DOM::Element const& element) -> DeprecatedString {
+        auto serialize_aria_properties_state_json = [](Web::DOM::Element const& element) -> ByteString {
             auto role_name = element.role_or_default();
             if (!role_name.has_value()) {
                 return "";
@@ -608,7 +608,7 @@ Messages::WebContentServer::InspectDomNodeResponse ConnectionFromClient::inspect
             auto serializer = MUST(JsonObjectSerializer<>::try_create(builder));
             MUST(role->serialize_as_json(serializer));
             MUST(serializer.finish());
-            return builder.to_deprecated_string();
+            return builder.to_byte_string();
         };
 
         if (pseudo_element.has_value()) {
@@ -620,18 +620,18 @@ Messages::WebContentServer::InspectDomNodeResponse ConnectionFromClient::inspect
             //        in a format we can use. So, we run the StyleComputer again to get the specified
             //        values, and have to ignore the computed values and custom properties.
             auto pseudo_element_style = MUST(page().page().focused_context().active_document()->style_computer().compute_style(element, pseudo_element));
-            DeprecatedString computed_values = serialize_json(pseudo_element_style);
-            DeprecatedString resolved_values = "{}";
-            DeprecatedString custom_properties_json = serialize_custom_properties_json(element, pseudo_element);
-            DeprecatedString node_box_sizing_json = serialize_node_box_sizing_json(pseudo_element_node.ptr());
+            ByteString computed_values = serialize_json(pseudo_element_style);
+            ByteString resolved_values = "{}";
+            ByteString custom_properties_json = serialize_custom_properties_json(element, pseudo_element);
+            ByteString node_box_sizing_json = serialize_node_box_sizing_json(pseudo_element_node.ptr());
             return { true, computed_values, resolved_values, custom_properties_json, node_box_sizing_json, "" };
         }
 
-        DeprecatedString computed_values = serialize_json(*element.computed_css_values());
-        DeprecatedString resolved_values_json = serialize_json(element.resolved_css_values());
-        DeprecatedString custom_properties_json = serialize_custom_properties_json(element, {});
-        DeprecatedString node_box_sizing_json = serialize_node_box_sizing_json(element.layout_node());
-        DeprecatedString aria_properties_state_json = serialize_aria_properties_state_json(element);
+        ByteString computed_values = serialize_json(*element.computed_css_values());
+        ByteString resolved_values_json = serialize_json(element.resolved_css_values());
+        ByteString custom_properties_json = serialize_custom_properties_json(element, {});
+        ByteString node_box_sizing_json = serialize_node_box_sizing_json(element.layout_node());
+        ByteString aria_properties_state_json = serialize_aria_properties_state_json(element);
         return { true, computed_values, resolved_values_json, custom_properties_json, node_box_sizing_json, aria_properties_state_json };
     }
 
@@ -668,7 +668,7 @@ Messages::WebContentServer::SetDomNodeTagResponse ConnectionFromClient::set_dom_
     auto new_element = Web::DOM::create_element(element.document(), name, element.namespace_uri(), element.prefix(), element.is_value()).release_value_but_fixme_should_propagate_errors();
 
     element.for_each_attribute([&](auto const& attribute) {
-        new_element->set_attribute_value(attribute.local_name(), attribute.value().to_deprecated_string(), attribute.prefix(), attribute.namespace_uri());
+        new_element->set_attribute_value(attribute.local_name(), attribute.value().to_byte_string(), attribute.prefix(), attribute.namespace_uri());
     });
 
     while (auto* child_node = element.first_child()) {
@@ -799,13 +799,13 @@ void ConnectionFromClient::destroy_js_console(Badge<PageClient>, Web::DOM::Docum
     m_console_clients.remove(&document);
 }
 
-void ConnectionFromClient::js_console_input(DeprecatedString const& js_source)
+void ConnectionFromClient::js_console_input(ByteString const& js_source)
 {
     if (m_top_level_document_console_client)
         m_top_level_document_console_client->handle_input(js_source);
 }
 
-void ConnectionFromClient::run_javascript(DeprecatedString const& js_source)
+void ConnectionFromClient::run_javascript(ByteString const& js_source)
 {
     auto* active_document = page().page().top_level_browsing_context().active_document();
 
@@ -870,7 +870,7 @@ Messages::WebContentServer::TakeDomNodeScreenshotResponse ConnectionFromClient::
 Messages::WebContentServer::DumpGcGraphResponse ConnectionFromClient::dump_gc_graph()
 {
     auto gc_graph_json = Web::Bindings::main_thread_vm().heap().dump_graph();
-    return MUST(String::from_deprecated_string(gc_graph_json.to_deprecated_string()));
+    return MUST(String::from_byte_string(gc_graph_json.to_byte_string()));
 }
 
 Messages::WebContentServer::GetSelectedTextResponse ConnectionFromClient::get_selected_text()
@@ -888,39 +888,39 @@ Messages::WebContentServer::DumpLayoutTreeResponse ConnectionFromClient::dump_la
 {
     auto* document = page().page().top_level_browsing_context().active_document();
     if (!document)
-        return DeprecatedString { "(no DOM tree)" };
+        return ByteString { "(no DOM tree)" };
     document->update_layout();
     auto* layout_root = document->layout_node();
     if (!layout_root)
-        return DeprecatedString { "(no layout tree)" };
+        return ByteString { "(no layout tree)" };
     StringBuilder builder;
     Web::dump_tree(builder, *layout_root);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 Messages::WebContentServer::DumpPaintTreeResponse ConnectionFromClient::dump_paint_tree()
 {
     auto* document = page().page().top_level_browsing_context().active_document();
     if (!document)
-        return DeprecatedString { "(no DOM tree)" };
+        return ByteString { "(no DOM tree)" };
     document->update_layout();
     auto* layout_root = document->layout_node();
     if (!layout_root)
-        return DeprecatedString { "(no layout tree)" };
+        return ByteString { "(no layout tree)" };
     if (!layout_root->paintable())
-        return DeprecatedString { "(no paint tree)" };
+        return ByteString { "(no paint tree)" };
     StringBuilder builder;
     Web::dump_tree(builder, *layout_root->paintable());
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 Messages::WebContentServer::DumpTextResponse ConnectionFromClient::dump_text()
 {
     auto* document = page().page().top_level_browsing_context().active_document();
     if (!document)
-        return DeprecatedString { "(no DOM tree)" };
+        return ByteString { "(no DOM tree)" };
     if (!document->body())
-        return DeprecatedString { "(no body)" };
+        return ByteString { "(no body)" };
     return document->body()->inner_text();
 }
 
@@ -941,12 +941,12 @@ void ConnectionFromClient::set_autoplay_allowlist(Vector<String> const& allowlis
     autoplay_allowlist.enable_for_origins(allowlist).release_value_but_fixme_should_propagate_errors();
 }
 
-void ConnectionFromClient::set_proxy_mappings(Vector<DeprecatedString> const& proxies, HashMap<DeprecatedString, size_t> const& mappings)
+void ConnectionFromClient::set_proxy_mappings(Vector<ByteString> const& proxies, HashMap<ByteString, size_t> const& mappings)
 {
     auto keys = mappings.keys();
     quick_sort(keys, [&](auto& a, auto& b) { return a.length() < b.length(); });
 
-    OrderedHashMap<DeprecatedString, size_t> sorted_mappings;
+    OrderedHashMap<ByteString, size_t> sorted_mappings;
     for (auto& key : keys) {
         auto value = *mappings.get(key);
         if (value >= proxies.size())
@@ -1082,7 +1082,7 @@ void ConnectionFromClient::set_user_style(String const& source)
 void ConnectionFromClient::inspect_accessibility_tree()
 {
     if (auto* doc = page().page().top_level_browsing_context().active_document()) {
-        async_did_get_accessibility_tree(doc->dump_accessibility_tree_as_json().to_deprecated_string());
+        async_did_get_accessibility_tree(doc->dump_accessibility_tree_as_json().to_byte_string());
     }
 }
 
diff --git a/Userland/Services/WebContent/ConnectionFromClient.h b/Userland/Services/WebContent/ConnectionFromClient.h
index a467b6d3129..611cb29bd29 100644
--- a/Userland/Services/WebContent/ConnectionFromClient.h
+++ b/Userland/Services/WebContent/ConnectionFromClient.h
@@ -52,12 +52,12 @@ private:
 
     virtual Messages::WebContentServer::GetWindowHandleResponse get_window_handle() override;
     virtual void set_window_handle(String const& handle) override;
-    virtual void connect_to_webdriver(DeprecatedString const& webdriver_ipc_path) override;
+    virtual void connect_to_webdriver(ByteString const& webdriver_ipc_path) override;
     virtual void update_system_theme(Core::AnonymousBuffer const&) override;
-    virtual void update_system_fonts(DeprecatedString const&, DeprecatedString const&, DeprecatedString const&) override;
+    virtual void update_system_fonts(ByteString const&, ByteString const&, ByteString const&) override;
     virtual void update_screen_rects(Vector<Web::DevicePixelRect> const&, u32) override;
     virtual void load_url(URL const&) override;
-    virtual void load_html(DeprecatedString const&) override;
+    virtual void load_html(ByteString const&) override;
     virtual void paint(Web::DevicePixelRect const&, i32) override;
     virtual void set_viewport_rect(Web::DevicePixelRect const&) override;
     virtual void mouse_down(Web::DevicePixelPoint, Web::DevicePixelPoint, unsigned, unsigned, unsigned) override;
@@ -69,7 +69,7 @@ private:
     virtual void key_up(i32, unsigned, u32) override;
     virtual void add_backing_store(i32, Gfx::ShareableBitmap const&) override;
     virtual void remove_backing_store(i32) override;
-    virtual void debug_request(DeprecatedString const&, DeprecatedString const&) override;
+    virtual void debug_request(ByteString const&, ByteString const&) override;
     virtual void get_source() override;
     virtual void inspect_dom_tree() override;
     virtual Messages::WebContentServer::InspectDomNodeResponse inspect_dom_node(i32 node_id, Optional<Web::CSS::Selector::PseudoElement::Type> const& pseudo_element) override;
@@ -92,7 +92,7 @@ private:
     virtual void set_content_filters(Vector<String> const&) override;
     virtual void set_autoplay_allowed_on_all_websites() override;
     virtual void set_autoplay_allowlist(Vector<String> const& allowlist) override;
-    virtual void set_proxy_mappings(Vector<DeprecatedString> const&, HashMap<DeprecatedString, size_t> const&) override;
+    virtual void set_proxy_mappings(Vector<ByteString> const&, HashMap<ByteString, size_t> const&) override;
     virtual void set_preferred_color_scheme(Web::CSS::PreferredColorScheme const&) override;
     virtual void set_has_focus(bool) override;
     virtual void set_is_scripting_enabled(bool) override;
@@ -102,8 +102,8 @@ private:
     virtual void handle_file_return(i32 error, Optional<IPC::File> const& file, i32 request_id) override;
     virtual void set_system_visibility_state(bool visible) override;
 
-    virtual void js_console_input(DeprecatedString const&) override;
-    virtual void run_javascript(DeprecatedString const&) override;
+    virtual void js_console_input(ByteString const&) override;
+    virtual void run_javascript(ByteString const&) override;
     virtual void js_console_request_messages(i32) override;
 
     virtual void alert_closed() override;
diff --git a/Userland/Services/WebContent/ConsoleGlobalEnvironmentExtensions.cpp b/Userland/Services/WebContent/ConsoleGlobalEnvironmentExtensions.cpp
index 61df4efe1e8..c6894ae02c8 100644
--- a/Userland/Services/WebContent/ConsoleGlobalEnvironmentExtensions.cpp
+++ b/Userland/Services/WebContent/ConsoleGlobalEnvironmentExtensions.cpp
@@ -68,7 +68,7 @@ JS_DEFINE_NATIVE_FUNCTION(ConsoleGlobalEnvironmentExtensions::$_function)
     auto* console_global_object = TRY(get_console(vm));
     auto& window = *console_global_object->m_window_object;
 
-    auto selector = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto selector = TRY(vm.argument(0).to_byte_string(vm));
 
     if (vm.argument_count() > 1) {
         auto element_value = vm.argument(1);
@@ -92,7 +92,7 @@ JS_DEFINE_NATIVE_FUNCTION(ConsoleGlobalEnvironmentExtensions::$$_function)
     auto* console_global_object = TRY(get_console(vm));
     auto& window = *console_global_object->m_window_object;
 
-    auto selector = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto selector = TRY(vm.argument(0).to_byte_string(vm));
 
     Web::DOM::ParentNode* element = &window.associated_document();
 
diff --git a/Userland/Services/WebContent/PageClient.cpp b/Userland/Services/WebContent/PageClient.cpp
index 825a8c652ea..411a0c83802 100644
--- a/Userland/Services/WebContent/PageClient.cpp
+++ b/Userland/Services/WebContent/PageClient.cpp
@@ -224,7 +224,7 @@ void PageClient::page_did_layout()
     client().async_did_layout(m_content_size.to_type<int>());
 }
 
-void PageClient::page_did_change_title(DeprecatedString const& title)
+void PageClient::page_did_change_title(ByteString const& title)
 {
     client().async_did_change_title(title);
 }
@@ -294,7 +294,7 @@ void PageClient::page_did_request_scroll_into_view(Web::CSSPixelRect const& rect
         device_pixel_rect.height().value() });
 }
 
-void PageClient::page_did_enter_tooltip_area(Web::CSSPixelPoint content_position, DeprecatedString const& title)
+void PageClient::page_did_enter_tooltip_area(Web::CSSPixelPoint content_position, ByteString const& title)
 {
     client().async_did_enter_tooltip_area({ content_position.x().to_int(), content_position.y().to_int() }, title);
 }
@@ -314,12 +314,12 @@ void PageClient::page_did_unhover_link()
     client().async_did_unhover_link();
 }
 
-void PageClient::page_did_click_link(const URL& url, DeprecatedString const& target, unsigned modifiers)
+void PageClient::page_did_click_link(const URL& url, ByteString const& target, unsigned modifiers)
 {
     client().async_did_click_link(url, target, modifiers);
 }
 
-void PageClient::page_did_middle_click_link(const URL& url, [[maybe_unused]] DeprecatedString const& target, [[maybe_unused]] unsigned modifiers)
+void PageClient::page_did_middle_click_link(const URL& url, [[maybe_unused]] ByteString const& target, [[maybe_unused]] unsigned modifiers)
 {
     client().async_did_middle_click_link(url, target, modifiers);
 }
@@ -354,18 +354,18 @@ void PageClient::page_did_request_context_menu(Web::CSSPixelPoint content_positi
     client().async_did_request_context_menu(page().css_to_device_point(content_position).to_type<int>());
 }
 
-void PageClient::page_did_request_link_context_menu(Web::CSSPixelPoint content_position, URL const& url, DeprecatedString const& target, unsigned modifiers)
+void PageClient::page_did_request_link_context_menu(Web::CSSPixelPoint content_position, URL const& url, ByteString const& target, unsigned modifiers)
 {
     client().async_did_request_link_context_menu(page().css_to_device_point(content_position).to_type<int>(), url, target, modifiers);
 }
 
-void PageClient::page_did_request_image_context_menu(Web::CSSPixelPoint content_position, URL const& url, DeprecatedString const& target, unsigned modifiers, Gfx::Bitmap const* bitmap_pointer)
+void PageClient::page_did_request_image_context_menu(Web::CSSPixelPoint content_position, URL const& url, ByteString const& target, unsigned modifiers, Gfx::Bitmap const* bitmap_pointer)
 {
     auto bitmap = bitmap_pointer ? bitmap_pointer->to_shareable_bitmap() : Gfx::ShareableBitmap();
     client().async_did_request_image_context_menu(page().css_to_device_point(content_position).to_type<int>(), url, target, modifiers, bitmap);
 }
 
-void PageClient::page_did_request_media_context_menu(Web::CSSPixelPoint content_position, DeprecatedString const& target, unsigned modifiers, Web::Page::MediaContextMenu menu)
+void PageClient::page_did_request_media_context_menu(Web::CSSPixelPoint content_position, ByteString const& target, unsigned modifiers, Web::Page::MediaContextMenu menu)
 {
     client().async_did_request_media_context_menu(page().css_to_device_point(content_position).to_type<int>(), target, modifiers, move(menu));
 }
@@ -460,12 +460,12 @@ Vector<Web::Cookie::Cookie> PageClient::page_did_request_all_cookies(URL const&
     return client().did_request_all_cookies(url);
 }
 
-Optional<Web::Cookie::Cookie> PageClient::page_did_request_named_cookie(URL const& url, DeprecatedString const& name)
+Optional<Web::Cookie::Cookie> PageClient::page_did_request_named_cookie(URL const& url, ByteString const& name)
 {
     return client().did_request_named_cookie(url, name);
 }
 
-DeprecatedString PageClient::page_did_request_cookie(const URL& url, Web::Cookie::Source source)
+ByteString PageClient::page_did_request_cookie(const URL& url, Web::Cookie::Source source)
 {
     auto response = client().send_sync_but_allow_failure<Messages::WebContentClient::DidRequestCookie>(move(url), static_cast<u8>(source));
     if (!response) {
@@ -589,7 +589,7 @@ void PageClient::inspector_did_execute_console_script(String const& script)
     client().async_inspector_did_execute_console_script(script);
 }
 
-ErrorOr<void> PageClient::connect_to_webdriver(DeprecatedString const& webdriver_ipc_path)
+ErrorOr<void> PageClient::connect_to_webdriver(ByteString const& webdriver_ipc_path)
 {
     VERIFY(!m_webdriver);
     m_webdriver = TRY(WebDriverConnection::connect(*this, webdriver_ipc_path));
diff --git a/Userland/Services/WebContent/PageClient.h b/Userland/Services/WebContent/PageClient.h
index ff7235caec6..da7a4ab4e48 100644
--- a/Userland/Services/WebContent/PageClient.h
+++ b/Userland/Services/WebContent/PageClient.h
@@ -31,7 +31,7 @@ public:
     virtual Web::Page& page() override { return *m_page; }
     virtual Web::Page const& page() const override { return *m_page; }
 
-    ErrorOr<void> connect_to_webdriver(DeprecatedString const& webdriver_ipc_path);
+    ErrorOr<void> connect_to_webdriver(ByteString const& webdriver_ipc_path);
 
     virtual void paint(Web::DevicePixelRect const& content_rect, Gfx::Bitmap&, Web::PaintOptions = {}) override;
 
@@ -78,7 +78,7 @@ private:
     virtual void page_did_change_selection() override;
     virtual void page_did_request_cursor_change(Gfx::StandardCursor) override;
     virtual void page_did_layout() override;
-    virtual void page_did_change_title(DeprecatedString const&) override;
+    virtual void page_did_change_title(ByteString const&) override;
     virtual void page_did_request_navigate_back() override;
     virtual void page_did_request_navigate_forward() override;
     virtual void page_did_request_refresh() override;
@@ -91,16 +91,16 @@ private:
     virtual void page_did_request_scroll(i32, i32) override;
     virtual void page_did_request_scroll_to(Web::CSSPixelPoint) override;
     virtual void page_did_request_scroll_into_view(Web::CSSPixelRect const&) override;
-    virtual void page_did_enter_tooltip_area(Web::CSSPixelPoint, DeprecatedString const&) override;
+    virtual void page_did_enter_tooltip_area(Web::CSSPixelPoint, ByteString const&) override;
     virtual void page_did_leave_tooltip_area() override;
     virtual void page_did_hover_link(const URL&) override;
     virtual void page_did_unhover_link() override;
-    virtual void page_did_click_link(const URL&, DeprecatedString const& target, unsigned modifiers) override;
-    virtual void page_did_middle_click_link(const URL&, DeprecatedString const& target, unsigned modifiers) override;
+    virtual void page_did_click_link(const URL&, ByteString const& target, unsigned modifiers) override;
+    virtual void page_did_middle_click_link(const URL&, ByteString const& target, unsigned modifiers) override;
     virtual void page_did_request_context_menu(Web::CSSPixelPoint) override;
-    virtual void page_did_request_link_context_menu(Web::CSSPixelPoint, URL const&, DeprecatedString const& target, unsigned modifiers) override;
-    virtual void page_did_request_image_context_menu(Web::CSSPixelPoint, const URL&, DeprecatedString const& target, unsigned modifiers, Gfx::Bitmap const*) override;
-    virtual void page_did_request_media_context_menu(Web::CSSPixelPoint, DeprecatedString const& target, unsigned modifiers, Web::Page::MediaContextMenu) override;
+    virtual void page_did_request_link_context_menu(Web::CSSPixelPoint, URL const&, ByteString const& target, unsigned modifiers) override;
+    virtual void page_did_request_image_context_menu(Web::CSSPixelPoint, const URL&, ByteString const& target, unsigned modifiers, Gfx::Bitmap const*) override;
+    virtual void page_did_request_media_context_menu(Web::CSSPixelPoint, ByteString const& target, unsigned modifiers, Web::Page::MediaContextMenu) override;
     virtual void page_did_start_loading(const URL&, bool) override;
     virtual void page_did_create_new_document(Web::DOM::Document&) override;
     virtual void page_did_destroy_document(Web::DOM::Document&) override;
@@ -113,8 +113,8 @@ private:
     virtual void page_did_request_dismiss_dialog() override;
     virtual void page_did_change_favicon(Gfx::Bitmap const&) override;
     virtual Vector<Web::Cookie::Cookie> page_did_request_all_cookies(URL const&) override;
-    virtual Optional<Web::Cookie::Cookie> page_did_request_named_cookie(URL const&, DeprecatedString const&) override;
-    virtual DeprecatedString page_did_request_cookie(const URL&, Web::Cookie::Source) override;
+    virtual Optional<Web::Cookie::Cookie> page_did_request_named_cookie(URL const&, ByteString const&) override;
+    virtual ByteString page_did_request_cookie(const URL&, Web::Cookie::Source) override;
     virtual void page_did_set_cookie(const URL&, Web::Cookie::ParsedCookie const&, Web::Cookie::Source) override;
     virtual void page_did_update_cookie(Web::Cookie::Cookie) override;
     virtual void page_did_update_resource_count(i32) override;
diff --git a/Userland/Services/WebContent/WebContentClient.ipc b/Userland/Services/WebContent/WebContentClient.ipc
index c96476e638a..402eb8dcf02 100644
--- a/Userland/Services/WebContent/WebContentClient.ipc
+++ b/Userland/Services/WebContent/WebContentClient.ipc
@@ -22,33 +22,33 @@ endpoint WebContentClient
     did_change_selection() =|
     did_request_cursor_change(i32 cursor_type) =|
     did_layout(Gfx::IntSize content_size) =|
-    did_change_title(DeprecatedString title) =|
+    did_change_title(ByteString title) =|
     did_request_scroll(i32 x_delta, i32 y_delta) =|
     did_request_scroll_to(Gfx::IntPoint scroll_position) =|
     did_request_scroll_into_view(Gfx::IntRect rect) =|
-    did_enter_tooltip_area(Gfx::IntPoint content_position, DeprecatedString title) =|
+    did_enter_tooltip_area(Gfx::IntPoint content_position, ByteString title) =|
     did_leave_tooltip_area() =|
     did_hover_link(URL url) =|
     did_unhover_link() =|
-    did_click_link(URL url, DeprecatedString target, unsigned modifiers) =|
-    did_middle_click_link(URL url, DeprecatedString target, unsigned modifiers) =|
+    did_click_link(URL url, ByteString target, unsigned modifiers) =|
+    did_middle_click_link(URL url, ByteString target, unsigned modifiers) =|
     did_request_context_menu(Gfx::IntPoint content_position) =|
-    did_request_link_context_menu(Gfx::IntPoint content_position, URL url, DeprecatedString target, unsigned modifiers) =|
-    did_request_image_context_menu(Gfx::IntPoint content_position, URL url, DeprecatedString target, unsigned modifiers, Gfx::ShareableBitmap bitmap) =|
-    did_request_media_context_menu(Gfx::IntPoint content_position, DeprecatedString target, unsigned modifiers, Web::Page::MediaContextMenu menu) =|
+    did_request_link_context_menu(Gfx::IntPoint content_position, URL url, ByteString target, unsigned modifiers) =|
+    did_request_image_context_menu(Gfx::IntPoint content_position, URL url, ByteString target, unsigned modifiers, Gfx::ShareableBitmap bitmap) =|
+    did_request_media_context_menu(Gfx::IntPoint content_position, ByteString target, unsigned modifiers, Web::Page::MediaContextMenu menu) =|
     did_request_alert(String message) =|
     did_request_confirm(String message) =|
     did_request_prompt(String message, String default_) =|
     did_request_set_prompt_text(String message) =|
     did_request_accept_dialog() =|
     did_request_dismiss_dialog() =|
-    did_get_source(URL url, DeprecatedString source) =|
-    did_get_dom_tree(DeprecatedString dom_tree) =|
-    did_get_accessibility_tree(DeprecatedString accessibility_tree) =|
+    did_get_source(URL url, ByteString source) =|
+    did_get_dom_tree(ByteString dom_tree) =|
+    did_get_accessibility_tree(ByteString accessibility_tree) =|
     did_change_favicon(Gfx::ShareableBitmap favicon) =|
     did_request_all_cookies(URL url) => (Vector<Web::Cookie::Cookie> cookies)
-    did_request_named_cookie(URL url, DeprecatedString name) => (Optional<Web::Cookie::Cookie> cookie)
-    did_request_cookie(URL url, u8 source) => (DeprecatedString cookie)
+    did_request_named_cookie(URL url, ByteString name) => (Optional<Web::Cookie::Cookie> cookie)
+    did_request_cookie(URL url, u8 source) => (ByteString cookie)
     did_set_cookie(URL url, Web::Cookie::ParsedCookie cookie, u8 source) =|
     did_update_cookie(Web::Cookie::Cookie cookie) =|
     did_update_resource_count(i32 count_waiting) =|
@@ -61,7 +61,7 @@ endpoint WebContentClient
     did_request_maximize_window() => (Gfx::IntRect window_rect)
     did_request_minimize_window() => (Gfx::IntRect window_rect)
     did_request_fullscreen_window() => (Gfx::IntRect window_rect)
-    did_request_file(DeprecatedString path, i32 request_id) =|
+    did_request_file(ByteString path, i32 request_id) =|
     did_request_color_picker(Color current_color) =|
     did_request_select_dropdown(Gfx::IntPoint content_position, i32 minimum_width, Vector<Web::HTML::SelectItem> items) =|
     did_finish_handling_input_event(bool event_was_accepted) =|
@@ -69,7 +69,7 @@ endpoint WebContentClient
     did_insert_clipboard_entry(String data, String presentation_style, String mime_type) =|
 
     did_output_js_console_message(i32 message_index) =|
-    did_get_js_console_messages(i32 start_index, Vector<DeprecatedString> message_types, Vector<DeprecatedString> messages) =|
+    did_get_js_console_messages(i32 start_index, Vector<ByteString> message_types, Vector<ByteString> messages) =|
 
     did_finish_text_test() =|
 
diff --git a/Userland/Services/WebContent/WebContentConsoleClient.cpp b/Userland/Services/WebContent/WebContentConsoleClient.cpp
index 917348070af..0bdb373fd64 100644
--- a/Userland/Services/WebContent/WebContentConsoleClient.cpp
+++ b/Userland/Services/WebContent/WebContentConsoleClient.cpp
@@ -31,7 +31,7 @@ WebContentConsoleClient::WebContentConsoleClient(JS::Console& console, JS::Realm
     m_console_global_environment_extensions = realm.heap().allocate<ConsoleGlobalEnvironmentExtensions>(realm, realm, window);
 }
 
-void WebContentConsoleClient::handle_input(DeprecatedString const& js_source)
+void WebContentConsoleClient::handle_input(ByteString const& js_source)
 {
     if (!m_console_global_environment_extensions)
         return;
@@ -46,16 +46,16 @@ void WebContentConsoleClient::handle_input(DeprecatedString const& js_source)
 
     if (result.value().has_value()) {
         m_console_global_environment_extensions->set_most_recent_result(result.value().value());
-        print_html(JS::MarkupGenerator::html_from_value(*result.value()).release_value_but_fixme_should_propagate_errors().to_deprecated_string());
+        print_html(JS::MarkupGenerator::html_from_value(*result.value()).release_value_but_fixme_should_propagate_errors().to_byte_string());
     }
 }
 
 void WebContentConsoleClient::report_exception(JS::Error const& exception, bool in_promise)
 {
-    print_html(JS::MarkupGenerator::html_from_error(exception, in_promise).release_value_but_fixme_should_propagate_errors().to_deprecated_string());
+    print_html(JS::MarkupGenerator::html_from_error(exception, in_promise).release_value_but_fixme_should_propagate_errors().to_byte_string());
 }
 
-void WebContentConsoleClient::print_html(DeprecatedString const& line)
+void WebContentConsoleClient::print_html(ByteString const& line)
 {
     m_message_log.append({ .type = ConsoleOutput::Type::HTML, .data = line });
     m_client.async_did_output_js_console_message(m_message_log.size() - 1);
@@ -67,7 +67,7 @@ void WebContentConsoleClient::clear_output()
     m_client.async_did_output_js_console_message(m_message_log.size() - 1);
 }
 
-void WebContentConsoleClient::begin_group(DeprecatedString const& label, bool start_expanded)
+void WebContentConsoleClient::begin_group(ByteString const& label, bool start_expanded)
 {
     m_message_log.append({ .type = start_expanded ? ConsoleOutput::Type::BeginGroup : ConsoleOutput::Type::BeginGroupCollapsed, .data = label });
     m_client.async_did_output_js_console_message(m_message_log.size() - 1);
@@ -93,8 +93,8 @@ void WebContentConsoleClient::send_messages(i32 start_index)
     }
 
     // FIXME: Replace with a single Vector of message structs
-    Vector<DeprecatedString> message_types;
-    Vector<DeprecatedString> messages;
+    Vector<ByteString> message_types;
+    Vector<ByteString> messages;
     message_types.ensure_capacity(messages_to_send);
     messages.ensure_capacity(messages_to_send);
 
@@ -152,7 +152,7 @@ JS::ThrowCompletionOr<JS::Value> WebContentConsoleClient::printer(JS::Console::L
 
     if (log_level == JS::Console::LogLevel::Group || log_level == JS::Console::LogLevel::GroupCollapsed) {
         auto group = arguments.get<JS::Console::Group>();
-        begin_group(DeprecatedString::formatted("<span style='{}'>{}</span>", styling, escape_html_entities(group.label)), log_level == JS::Console::LogLevel::Group);
+        begin_group(ByteString::formatted("<span style='{}'>{}</span>", styling, escape_html_entities(group.label)), log_level == JS::Console::LogLevel::Group);
         return JS::js_undefined();
     }
 
diff --git a/Userland/Services/WebContent/WebContentConsoleClient.h b/Userland/Services/WebContent/WebContentConsoleClient.h
index 237ab1c07d8..43764a9c729 100644
--- a/Userland/Services/WebContent/WebContentConsoleClient.h
+++ b/Userland/Services/WebContent/WebContentConsoleClient.h
@@ -21,7 +21,7 @@ class WebContentConsoleClient final : public JS::ConsoleClient
 public:
     WebContentConsoleClient(JS::Console&, JS::Realm&, ConnectionFromClient&);
 
-    void handle_input(DeprecatedString const& js_source);
+    void handle_input(ByteString const& js_source);
     void send_messages(i32 start_index);
     void report_exception(JS::Error const&, bool) override;
 
@@ -39,8 +39,8 @@ private:
     JS::Handle<ConsoleGlobalEnvironmentExtensions> m_console_global_environment_extensions;
 
     void clear_output();
-    void print_html(DeprecatedString const& line);
-    void begin_group(DeprecatedString const& label, bool start_expanded);
+    void print_html(ByteString const& line);
+    void begin_group(ByteString const& label, bool start_expanded);
     virtual void end_group() override;
 
     struct ConsoleOutput {
@@ -52,7 +52,7 @@ private:
             EndGroup,
         };
         Type type;
-        DeprecatedString data;
+        ByteString data;
     };
     Vector<ConsoleOutput> m_message_log;
 
diff --git a/Userland/Services/WebContent/WebContentServer.ipc b/Userland/Services/WebContent/WebContentServer.ipc
index 0a56041387c..1645e5856bf 100644
--- a/Userland/Services/WebContent/WebContentServer.ipc
+++ b/Userland/Services/WebContent/WebContentServer.ipc
@@ -13,14 +13,14 @@ endpoint WebContentServer
     get_window_handle() => (String handle)
     set_window_handle(String handle) =|
 
-    connect_to_webdriver(DeprecatedString webdriver_ipc_path) =|
+    connect_to_webdriver(ByteString webdriver_ipc_path) =|
 
     update_system_theme(Core::AnonymousBuffer theme_buffer) =|
-    update_system_fonts(DeprecatedString default_font_query, DeprecatedString fixed_width_font_query, DeprecatedString window_title_font_query) =|
+    update_system_fonts(ByteString default_font_query, ByteString fixed_width_font_query, ByteString window_title_font_query) =|
     update_screen_rects(Vector<Web::DevicePixelRect> rects, u32 main_screen_index) =|
 
     load_url(URL url) =|
-    load_html(DeprecatedString html) =|
+    load_html(ByteString html) =|
 
     add_backing_store(i32 backing_store_id, Gfx::ShareableBitmap bitmap) =|
     remove_backing_store(i32 backing_store_id) =|
@@ -37,13 +37,13 @@ endpoint WebContentServer
     key_down(i32 key, unsigned modifiers, u32 code_point) =|
     key_up(i32 key, unsigned modifiers, u32 code_point) =|
 
-    debug_request(DeprecatedString request, DeprecatedString argument) =|
+    debug_request(ByteString request, ByteString argument) =|
     get_source() =|
     inspect_dom_tree() =|
-    inspect_dom_node(i32 node_id, Optional<Web::CSS::Selector::PseudoElement::Type> pseudo_element) => (bool has_style, DeprecatedString computed_style,  DeprecatedString resolved_style,  DeprecatedString custom_properties, DeprecatedString node_box_sizing, DeprecatedString aria_properties_state)
+    inspect_dom_node(i32 node_id, Optional<Web::CSS::Selector::PseudoElement::Type> pseudo_element) => (bool has_style, ByteString computed_style,  ByteString resolved_style,  ByteString custom_properties, ByteString node_box_sizing, ByteString aria_properties_state)
     inspect_accessibility_tree() =|
     get_hovered_node_id() => (i32 node_id)
-    js_console_input(DeprecatedString js_source) =|
+    js_console_input(ByteString js_source) =|
     js_console_request_messages(i32 start_index) =|
 
     set_dom_node_text(i32 node_id, String text) =|
@@ -61,19 +61,19 @@ endpoint WebContentServer
 
     dump_gc_graph() => (String json)
 
-    run_javascript(DeprecatedString js_source) =|
+    run_javascript(ByteString js_source) =|
 
-    dump_layout_tree() => (DeprecatedString dump)
-    dump_paint_tree() => (DeprecatedString dump)
-    dump_text() => (DeprecatedString dump)
+    dump_layout_tree() => (ByteString dump)
+    dump_paint_tree() => (ByteString dump)
+    dump_text() => (ByteString dump)
 
-    get_selected_text() => (DeprecatedString selection)
+    get_selected_text() => (ByteString selection)
     select_all() =|
 
     set_content_filters(Vector<String> filters) =|
     set_autoplay_allowed_on_all_websites() =|
     set_autoplay_allowlist(Vector<String> allowlist) =|
-    set_proxy_mappings(Vector<DeprecatedString> proxies, HashMap<DeprecatedString,size_t> mappings) =|
+    set_proxy_mappings(Vector<ByteString> proxies, HashMap<ByteString,size_t> mappings) =|
     set_preferred_color_scheme(Web::CSS::PreferredColorScheme color_scheme) =|
     set_has_focus(bool has_focus) =|
     set_is_scripting_enabled(bool is_scripting_enabled) =|
diff --git a/Userland/Services/WebContent/WebDriverConnection.cpp b/Userland/Services/WebContent/WebDriverConnection.cpp
index db166b20feb..c7e7a910381 100644
--- a/Userland/Services/WebContent/WebDriverConnection.cpp
+++ b/Userland/Services/WebContent/WebDriverConnection.cpp
@@ -51,10 +51,10 @@ namespace WebContent {
 static JsonValue serialize_cookie(Web::Cookie::Cookie const& cookie)
 {
     JsonObject serialized_cookie;
-    serialized_cookie.set("name"sv, cookie.name.to_deprecated_string());
-    serialized_cookie.set("value"sv, cookie.value.to_deprecated_string());
-    serialized_cookie.set("path"sv, cookie.path.to_deprecated_string());
-    serialized_cookie.set("domain"sv, cookie.domain.to_deprecated_string());
+    serialized_cookie.set("name"sv, cookie.name.to_byte_string());
+    serialized_cookie.set("value"sv, cookie.value.to_byte_string());
+    serialized_cookie.set("path"sv, cookie.path.to_byte_string());
+    serialized_cookie.set("domain"sv, cookie.domain.to_byte_string());
     serialized_cookie.set("secure"sv, cookie.secure);
     serialized_cookie.set("httpOnly"sv, cookie.http_only);
     serialized_cookie.set("expiry"sv, cookie.expiry_time.seconds_since_epoch());
@@ -116,21 +116,21 @@ static Gfx::IntRect calculate_absolute_rect_of_element(Web::Page const& page, We
 }
 
 // https://w3c.github.io/webdriver/#dfn-get-or-create-a-web-element-reference
-static DeprecatedString get_or_create_a_web_element_reference(Web::DOM::Node const& element)
+static ByteString get_or_create_a_web_element_reference(Web::DOM::Node const& element)
 {
     // FIXME: 1. For each known element of the current browsing context’s list of known elements:
     // FIXME:     1. If known element equals element, return success with known element’s web element reference.
     // FIXME: 2. Add element to the list of known elements of the current browsing context.
     // FIXME: 3. Return success with the element’s web element reference.
 
-    return DeprecatedString::number(element.unique_id());
+    return ByteString::number(element.unique_id());
 }
 
 // https://w3c.github.io/webdriver/#dfn-web-element-reference-object
 static JsonObject web_element_reference_object(Web::DOM::Node const& element)
 {
     // https://w3c.github.io/webdriver/#dfn-web-element-identifier
-    static DeprecatedString const web_element_identifier = "element-6066-11e4-a52e-4f735466cecf"sv;
+    static ByteString const web_element_identifier = "element-6066-11e4-a52e-4f735466cecf"sv;
 
     // 1. Let identifier be the web element identifier.
     auto identifier = web_element_identifier;
@@ -157,27 +157,27 @@ static ErrorOr<Web::DOM::Element*, Web::WebDriver::Error> get_known_connected_el
     auto* node = Web::DOM::Node::from_unique_id(*element);
 
     if (!node || !node->is_element())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchElement, DeprecatedString::formatted("Could not find element with ID: {}", element_id));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchElement, ByteString::formatted("Could not find element with ID: {}", element_id));
 
     return static_cast<Web::DOM::Element*>(node);
 }
 
 // https://w3c.github.io/webdriver/#dfn-get-or-create-a-shadow-root-reference
-static DeprecatedString get_or_create_a_shadow_root_reference(Web::DOM::ShadowRoot const& shadow_root)
+static ByteString get_or_create_a_shadow_root_reference(Web::DOM::ShadowRoot const& shadow_root)
 {
     // FIXME: 1. For each known shadow root of the current browsing context’s list of known shadow roots:
     // FIXME:     1. If known shadow root equals shadow root, return success with known shadow root’s shadow root reference.
     // FIXME: 2. Add shadow to the list of known shadow roots of the current browsing context.
     // FIXME: 3. Return success with the shadow’s shadow root reference.
 
-    return DeprecatedString::number(shadow_root.unique_id());
+    return ByteString::number(shadow_root.unique_id());
 }
 
 // https://w3c.github.io/webdriver/#dfn-shadow-root-reference-object
 static JsonObject shadow_root_reference_object(Web::DOM::ShadowRoot const& shadow_root)
 {
     // https://w3c.github.io/webdriver/#dfn-shadow-root-identifier
-    static DeprecatedString const shadow_root_identifier = "shadow-6066-11e4-a52e-4f735466cecf"sv;
+    static ByteString const shadow_root_identifier = "shadow-6066-11e4-a52e-4f735466cecf"sv;
 
     // 1. Let identifier be the shadow root identifier.
     auto identifier = shadow_root_identifier;
@@ -204,7 +204,7 @@ static ErrorOr<Web::DOM::ShadowRoot*, Web::WebDriver::Error> get_known_shadow_ro
     auto* node = Web::DOM::Node::from_unique_id(*shadow_root);
 
     if (!node || !node->is_shadow_root())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchElement, DeprecatedString::formatted("Could not find shadow root with ID: {}", shadow_id));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchElement, ByteString::formatted("Could not find shadow root with ID: {}", shadow_id));
 
     return static_cast<Web::DOM::ShadowRoot*>(node);
 }
@@ -227,7 +227,7 @@ static ErrorOr<void> scroll_element_into_view(Web::DOM::Element& element)
     return {};
 }
 
-template<typename PropertyType = DeprecatedString>
+template<typename PropertyType = ByteString>
 static ErrorOr<PropertyType, Web::WebDriver::Error> get_property(JsonValue const& payload, StringView key)
 {
     if (!payload.is_object())
@@ -236,27 +236,27 @@ static ErrorOr<PropertyType, Web::WebDriver::Error> get_property(JsonValue const
     auto property = payload.as_object().get(key);
 
     if (!property.has_value())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("No property called '{}' present", key));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("No property called '{}' present", key));
 
-    if constexpr (IsSame<PropertyType, DeprecatedString>) {
+    if constexpr (IsSame<PropertyType, ByteString>) {
         if (!property->is_string())
-            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Property '{}' is not a String", key));
+            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Property '{}' is not a String", key));
         return property->as_string();
     } else if constexpr (IsSame<PropertyType, bool>) {
         if (!property->is_bool())
-            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Property '{}' is not a Boolean", key));
+            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Property '{}' is not a Boolean", key));
         return property->as_bool();
     } else if constexpr (IsSame<PropertyType, u32>) {
         if (!property->is_u32())
-            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Property '{}' is not a Number", key));
+            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Property '{}' is not a Number", key));
         return property->as_u32();
     } else if constexpr (IsSame<PropertyType, JsonArray const*>) {
         if (!property->is_array())
-            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Property '{}' is not an Array", key));
+            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Property '{}' is not an Array", key));
         return &property->as_array();
     } else if constexpr (IsSame<PropertyType, JsonObject const*>) {
         if (!property->is_object())
-            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Property '{}' is not an Object", key));
+            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Property '{}' is not an Object", key));
         return &property->as_object();
     } else {
         static_assert(DependentFalse<PropertyType>, "get_property invoked with unknown property type");
@@ -321,7 +321,7 @@ static bool fire_an_event(FlyString name, Optional<Web::DOM::Element&> target)
     return target->dispatch_event(event);
 }
 
-ErrorOr<NonnullRefPtr<WebDriverConnection>> WebDriverConnection::connect(Web::PageClient& page_client, DeprecatedString const& webdriver_ipc_path)
+ErrorOr<NonnullRefPtr<WebDriverConnection>> WebDriverConnection::connect(Web::PageClient& page_client, ByteString const& webdriver_ipc_path)
 {
     dbgln_if(WEBDRIVER_DEBUG, "Trying to connect to {}", webdriver_ipc_path);
     auto socket = TRY(Core::LocalSocket::connect(webdriver_ipc_path));
@@ -403,7 +403,7 @@ Messages::WebDriverClient::NavigateToResponse WebDriverConnection::navigate_to(J
     // 2. Let url be the result of getting the property url from the parameters argument.
     if (!payload.is_object() || !payload.as_object().has_string("url"sv))
         return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "Payload doesn't have a string `url`"sv);
-    URL url(payload.as_object().get_deprecated_string("url"sv).value());
+    URL url(payload.as_object().get_byte_string("url"sv).value());
 
     // FIXME: 3. If url is not an absolute URL or is not an absolute URL with fragment or not a local scheme, return error with error code invalid argument.
 
@@ -445,7 +445,7 @@ Messages::WebDriverClient::GetCurrentUrlResponse WebDriverConnection::get_curren
     TRY(handle_any_user_prompts());
 
     // 3. Let url be the serialization of the current top-level browsing context’s active document’s document URL.
-    auto url = m_page_client.page().top_level_browsing_context().active_document()->url().to_deprecated_string();
+    auto url = m_page_client.page().top_level_browsing_context().active_document()->url().to_byte_string();
 
     // 4. Return success with data url.
     return url;
@@ -523,7 +523,7 @@ Messages::WebDriverClient::GetTitleResponse WebDriverConnection::get_title()
     auto title = m_page_client.page().top_level_browsing_context().active_document()->title();
 
     // 4. Return success with data title.
-    return title.to_deprecated_string();
+    return title.to_byte_string();
 }
 
 // 11.1 Get Window Handle, https://w3c.github.io/webdriver/#get-window-handle
@@ -621,14 +621,14 @@ Messages::WebDriverClient::SetWindowRectResponse WebDriverConnection::set_window
         if (property.is_null())
             return Optional<i32> {};
         if (!property.is_number())
-            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Property '{}' is not a Number", name));
+            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Property '{}' is not a Number", name));
 
         auto number = property.template to_number<i64>();
 
         if (number < min)
-            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Property '{}' value {} exceeds the minimum allowed value {}", name, number, min));
+            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Property '{}' value {} exceeds the minimum allowed value {}", name, number, min));
         if (number > max)
-            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Property '{}' value {} exceeds the maximum allowed value {}", name, number, max));
+            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Property '{}' value {} exceeds the maximum allowed value {}", name, number, max));
 
         return static_cast<i32>(number);
     };
@@ -766,7 +766,7 @@ Messages::WebDriverClient::FindElementResponse WebDriverConnection::find_element
 
     // 2. If location strategy is not present as a keyword in the table of location strategies, return error with error code invalid argument.
     if (!location_strategy.has_value())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Location strategy '{}' is invalid", location_strategy_string));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Location strategy '{}' is invalid", location_strategy_string));
 
     // 3. Let selector be the result of getting a property called "value".
     // 4. If selector is undefined, return error with error code invalid argument.
@@ -808,7 +808,7 @@ Messages::WebDriverClient::FindElementsResponse WebDriverConnection::find_elemen
 
     // 2. If location strategy is not present as a keyword in the table of location strategies, return error with error code invalid argument.
     if (!location_strategy.has_value())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Location strategy '{}' is invalid", location_strategy_string));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Location strategy '{}' is invalid", location_strategy_string));
 
     // 3. Let selector be the result of getting a property called "value".
     // 4. If selector is undefined, return error with error code invalid argument.
@@ -844,7 +844,7 @@ Messages::WebDriverClient::FindElementFromElementResponse WebDriverConnection::f
 
     // 2. If location strategy is not present as a keyword in the table of location strategies, return error with error code invalid argument.
     if (!location_strategy.has_value())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Location strategy '{}' is invalid", location_strategy_string));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Location strategy '{}' is invalid", location_strategy_string));
 
     // 3. Let selector be the result of getting a property called "value".
     // 4. If selector is undefined, return error with error code invalid argument.
@@ -880,7 +880,7 @@ Messages::WebDriverClient::FindElementsFromElementResponse WebDriverConnection::
 
     // 2. If location strategy is not present as a keyword in the table of location strategies, return error with error code invalid argument.
     if (!location_strategy.has_value())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Location strategy '{}' is invalid", location_strategy_string));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Location strategy '{}' is invalid", location_strategy_string));
 
     // 3. Let selector be the result of getting a property called "value".
     // 4. If selector is undefined, return error with error code invalid argument.
@@ -910,7 +910,7 @@ Messages::WebDriverClient::FindElementFromShadowRootResponse WebDriverConnection
 
     // 2. If location strategy is not present as a keyword in the table of location strategies, return error with error code invalid argument.
     if (!location_strategy.has_value())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Location strategy '{}' is invalid", location_strategy_string));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Location strategy '{}' is invalid", location_strategy_string));
 
     // 3. Let selector be the result of getting a property called "value".
     // 4. If selector is undefined, return error with error code invalid argument.
@@ -946,7 +946,7 @@ Messages::WebDriverClient::FindElementsFromShadowRootResponse WebDriverConnectio
 
     // 2. If location strategy is not present as a keyword in the table of location strategies, return error with error code invalid argument.
     if (!location_strategy.has_value())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, DeprecatedString::formatted("Location strategy '{}' is invalid", location_strategy_string));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, ByteString::formatted("Location strategy '{}' is invalid", location_strategy_string));
 
     // 3. Let selector be the result of getting a property called "value".
     // 4. If selector is undefined, return error with error code invalid argument.
@@ -982,7 +982,7 @@ Messages::WebDriverClient::GetActiveElementResponse WebDriverConnection::get_act
     // 4. If active element is a non-null element, return success with data set to web element reference object for active element.
     //    Otherwise, return error with error code no such element.
     if (active_element)
-        return DeprecatedString::number(active_element->unique_id());
+        return ByteString::number(active_element->unique_id());
 
     return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchElement, "The current document does not have an active element"sv);
 }
@@ -1004,7 +1004,7 @@ Messages::WebDriverClient::GetElementShadowRootResponse WebDriverConnection::get
 
     // 5. If shadow root is null, return error with error code no such shadow root.
     if (!shadow_root)
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchShadowRoot, DeprecatedString::formatted("Element with ID '{}' does not have a shadow root", element_id));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchShadowRoot, ByteString::formatted("Element with ID '{}' does not have a shadow root", element_id));
 
     // 6. Let serialized be the shadow root reference object for shadow root.
     auto serialized = shadow_root_reference_object(*shadow_root);
@@ -1062,7 +1062,7 @@ Messages::WebDriverClient::GetElementAttributeResponse WebDriverConnection::get_
     auto* element = TRY(get_known_connected_element(element_id));
 
     // 4. Let result be the result of the first matching condition:
-    Optional<DeprecatedString> result;
+    Optional<ByteString> result;
 
     // -> If name is a boolean attribute
     if (Web::HTML::is_boolean_attribute(name)) {
@@ -1094,15 +1094,15 @@ Messages::WebDriverClient::GetElementPropertyResponse WebDriverConnection::get_e
     // 3. Let element be the result of trying to get a known connected element with url variable element id.
     auto* element = TRY(get_known_connected_element(element_id));
 
-    Optional<DeprecatedString> result;
+    Optional<ByteString> result;
 
     // 4. Let property be the result of calling the Object.[[GetProperty]](name) on element.
-    if (auto property_or_error = element->get(name.to_deprecated_string()); !property_or_error.is_throw_completion()) {
+    if (auto property_or_error = element->get(name.to_byte_string()); !property_or_error.is_throw_completion()) {
         auto property = property_or_error.release_value();
 
         // 5. Let result be the value of property if not undefined, or null.
         if (!property.is_undefined()) {
-            if (auto string_or_error = property.to_deprecated_string(element->vm()); !string_or_error.is_error())
+            if (auto string_or_error = property.to_byte_string(element->vm()); !string_or_error.is_error())
                 result = string_or_error.release_value();
         }
     }
@@ -1126,20 +1126,20 @@ Messages::WebDriverClient::GetElementCssValueResponse WebDriverConnection::get_e
     auto* element = TRY(get_known_connected_element(element_id));
 
     // 4. Let computed value be the result of the first matching condition:
-    DeprecatedString computed_value;
+    ByteString computed_value;
 
     // -> current browsing context’s active document’s type is not "xml"
     if (!m_page_client.page().top_level_browsing_context().active_document()->is_xml_document()) {
         // computed value of parameter property name from element’s style declarations. property name is obtained from url variables.
         if (auto property = Web::CSS::property_id_from_string(name); property.has_value()) {
             if (auto* computed_values = element->computed_css_values())
-                computed_value = computed_values->property(property.value())->to_string().to_deprecated_string();
+                computed_value = computed_values->property(property.value())->to_string().to_byte_string();
         }
     }
     // -> Otherwise
     else {
         // "" (empty string)
-        computed_value = DeprecatedString::empty();
+        computed_value = ByteString::empty();
     }
 
     // 5. Return success with data computed value.
@@ -1162,7 +1162,7 @@ Messages::WebDriverClient::GetElementTextResponse WebDriverConnection::get_eleme
     auto rendered_text = element->text_content();
 
     // 5. Return success with data rendered text.
-    return rendered_text.value_or(String {}).to_deprecated_string();
+    return rendered_text.value_or(String {}).to_byte_string();
 }
 
 // 12.4.6 Get Element Tag Name, https://w3c.github.io/webdriver/#dfn-get-element-tag-name
@@ -1278,7 +1278,7 @@ Messages::WebDriverClient::GetComputedLabelResponse WebDriverConnection::get_com
     auto label = element->accessible_name(element->document()).release_value_but_fixme_should_propagate_errors();
 
     // 5. Return success with data label.
-    return label.to_deprecated_string();
+    return label.to_byte_string();
 }
 
 // 12.5.1 Element Click, https://w3c.github.io/webdriver/#element-click
@@ -1418,15 +1418,15 @@ Messages::WebDriverClient::GetSourceResponse WebDriverConnection::get_source()
     TRY(handle_any_user_prompts());
 
     auto* document = m_page_client.page().top_level_browsing_context().active_document();
-    Optional<DeprecatedString> source;
+    Optional<ByteString> source;
 
     // 3. Let source be the result of invoking the fragment serializing algorithm on a fictional node whose only child is the document element providing true for the require well-formed flag. If this causes an exception to be thrown, let source be null.
     if (auto result = document->serialize_fragment(Web::DOMParsing::RequireWellFormed::Yes); !result.is_error())
-        source = result.release_value().to_deprecated_string();
+        source = result.release_value().to_byte_string();
 
     // 4. Let source be the result of serializing to string the current browsing context active document, if source is null.
     if (!source.has_value())
-        source = MUST(document->serialize_fragment(Web::DOMParsing::RequireWellFormed::No)).to_deprecated_string();
+        source = MUST(document->serialize_fragment(Web::DOMParsing::RequireWellFormed::No)).to_byte_string();
 
     // 5. Return success with data source.
     return source.release_value();
@@ -1539,13 +1539,13 @@ Messages::WebDriverClient::GetNamedCookieResponse WebDriverConnection::get_named
     // 3. If the url variable name is equal to a cookie’s cookie name amongst all associated cookies of the current browsing context’s active document, return success with the serialized cookie as data.
     auto* document = m_page_client.page().top_level_browsing_context().active_document();
 
-    if (auto cookie = m_page_client.page_did_request_named_cookie(document->url(), name.to_deprecated_string()); cookie.has_value()) {
+    if (auto cookie = m_page_client.page_did_request_named_cookie(document->url(), name.to_byte_string()); cookie.has_value()) {
         auto serialized_cookie = serialize_cookie(*cookie);
         return serialized_cookie;
     }
 
     // 4. Otherwise, return error with error code no such cookie.
-    return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchCookie, DeprecatedString::formatted("Cookie '{}' not found", name));
+    return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::NoSuchCookie, ByteString::formatted("Cookie '{}' not found", name));
 }
 
 // 14.3 Add Cookie, https://w3c.github.io/webdriver/#dfn-adding-a-cookie
@@ -1570,13 +1570,13 @@ Messages::WebDriverClient::AddCookieResponse WebDriverConnection::add_cookie(Jso
 
     // 7. Create a cookie in the cookie store associated with the active document’s address using cookie name name, cookie value value, and an attribute-value list of the following cookie concepts listed in the table for cookie conversion from data:
     Web::Cookie::ParsedCookie cookie {};
-    cookie.name = MUST(String::from_deprecated_string(TRY(get_property(data, "name"sv))));
-    cookie.value = MUST(String::from_deprecated_string(TRY(get_property(data, "value"sv))));
+    cookie.name = MUST(String::from_byte_string(TRY(get_property(data, "name"sv))));
+    cookie.value = MUST(String::from_byte_string(TRY(get_property(data, "value"sv))));
 
     // Cookie path
     //     The value if the entry exists, otherwise "/".
     if (data.has("path"sv))
-        cookie.path = MUST(String::from_deprecated_string(TRY(get_property(data, "path"sv))));
+        cookie.path = MUST(String::from_byte_string(TRY(get_property(data, "path"sv))));
     else
         cookie.path = "/"_string;
 
@@ -1584,7 +1584,7 @@ Messages::WebDriverClient::AddCookieResponse WebDriverConnection::add_cookie(Jso
     //     The value if the entry exists, otherwise the current browsing context’s active document’s URL domain.
     // NOTE: The otherwise case is handled by the CookieJar
     if (data.has("domain"sv))
-        cookie.domain = MUST(String::from_deprecated_string(TRY(get_property(data, "domain"sv))));
+        cookie.domain = MUST(String::from_byte_string(TRY(get_property(data, "domain"sv))));
 
     // Cookie secure only
     //     The value if the entry exists, otherwise false.
@@ -1722,7 +1722,7 @@ Messages::WebDriverClient::GetAlertTextResponse WebDriverConnection::get_alert_t
 
     // 4. Return success with data message.
     if (message.has_value())
-        return message->to_deprecated_string();
+        return message->to_byte_string();
     return JsonValue {};
 }
 
@@ -1761,7 +1761,7 @@ Messages::WebDriverClient::SendAlertTextResponse WebDriverConnection::send_alert
     }
 
     // 6. Perform user agent dependent steps to set the value of current user prompt’s text field to text.
-    m_page_client.page_did_request_set_prompt_text(TRY(String::from_deprecated_string(text)));
+    m_page_client.page_did_request_set_prompt_text(TRY(String::from_byte_string(text)));
 
     // 7. Return success with data null.
     return JsonValue {};
@@ -1997,7 +1997,7 @@ ErrorOr<JsonArray, Web::WebDriver::Error> WebDriverConnection::find(StartNodeGet
 
         // 5. If a DOMException, SyntaxError, XPathException, or other error occurs during the execution of the element location strategy, return error invalid selector.
         if (elements.is_error())
-            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidSelector, DeprecatedString::formatted("The location strategy could not finish: {}", elements.error().message));
+            return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidSelector, ByteString::formatted("The location strategy could not finish: {}", elements.error().message));
 
         return elements.release_value();
     };
diff --git a/Userland/Services/WebContent/WebDriverConnection.h b/Userland/Services/WebContent/WebDriverConnection.h
index 6c46fd0df7a..6bca2dbce1d 100644
--- a/Userland/Services/WebContent/WebDriverConnection.h
+++ b/Userland/Services/WebContent/WebDriverConnection.h
@@ -8,7 +8,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/HashMap.h>
 #include <AK/String.h>
@@ -31,7 +31,7 @@ class WebDriverConnection final
     C_OBJECT_ABSTRACT(WebDriverConnection)
 
 public:
-    static ErrorOr<NonnullRefPtr<WebDriverConnection>> connect(Web::PageClient& page_client, DeprecatedString const& webdriver_ipc_path);
+    static ErrorOr<NonnullRefPtr<WebDriverConnection>> connect(Web::PageClient& page_client, ByteString const& webdriver_ipc_path);
     virtual ~WebDriverConnection() = default;
 
 private:
@@ -111,7 +111,7 @@ private:
     ErrorOr<JsonArray, Web::WebDriver::Error> find(StartNodeGetter&& start_node_getter, Web::WebDriver::LocationStrategy using_, StringView value);
 
     struct ScriptArguments {
-        DeprecatedString script;
+        ByteString script;
         JS::MarkedVector<JS::Value> arguments;
     };
     ErrorOr<ScriptArguments, Web::WebDriver::Error> extract_the_script_arguments_from_a_request(JsonValue const& payload);
diff --git a/Userland/Services/WebContent/main.cpp b/Userland/Services/WebContent/main.cpp
index df2a2fffd47..bb531380e5c 100644
--- a/Userland/Services/WebContent/main.cpp
+++ b/Userland/Services/WebContent/main.cpp
@@ -30,7 +30,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
     TRY(Core::System::pledge("stdio recvfd sendfd accept unix rpath thread proc"));
 
     // This must be first; we can't check if /tmp/webdriver exists once we've unveiled other paths.
-    auto webdriver_socket_path = DeprecatedString::formatted("{}/webdriver", TRY(Core::StandardPaths::runtime_directory()));
+    auto webdriver_socket_path = ByteString::formatted("{}/webdriver", TRY(Core::StandardPaths::runtime_directory()));
     if (FileSystem::exists(webdriver_socket_path))
         TRY(Core::System::unveil(webdriver_socket_path, "rw"sv));
 
diff --git a/Userland/Services/WebDriver/Client.cpp b/Userland/Services/WebDriver/Client.cpp
index 8f5583293d1..19151711755 100644
--- a/Userland/Services/WebDriver/Client.cpp
+++ b/Userland/Services/WebDriver/Client.cpp
@@ -61,7 +61,7 @@ void Client::close_session(unsigned session_id)
 static void initialize_session_from_capabilities(WebContentConnection& web_content_connection, JsonObject& capabilities)
 {
     // 1. Let strategy be the result of getting property "pageLoadStrategy" from capabilities.
-    auto strategy = capabilities.get_deprecated_string("pageLoadStrategy"sv);
+    auto strategy = capabilities.get_byte_string("pageLoadStrategy"sv);
 
     // 2. If strategy is a string, set the current session’s page loading strategy to strategy. Otherwise, set the page loading strategy to normal and set a property of capabilities with name "pageLoadStrategy" and value "normal".
     if (strategy.has_value())
@@ -97,7 +97,7 @@ static void initialize_session_from_capabilities(WebContentConnection& web_conte
     }
 
     // 8. Apply changes to the user agent for any implementation-defined capabilities selected during the capabilities processing step.
-    auto behavior = capabilities.get_deprecated_string("unhandledPromptBehavior"sv);
+    auto behavior = capabilities.get_byte_string("unhandledPromptBehavior"sv);
     if (behavior.has_value())
         web_content_connection.async_set_unhandled_prompt_behavior(Web::WebDriver::unhandled_prompt_behavior_from_string(*behavior));
     else
@@ -139,7 +139,7 @@ Web::WebDriver::Response Client::new_session(Web::WebDriver::Parameters, JsonVal
     auto session = make_ref_counted<Session>(session_id, *this, move(options));
 
     if (auto start_result = session->start(m_callbacks); start_result.is_error())
-        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::SessionNotCreated, DeprecatedString::formatted("Failed to start session: {}", start_result.error()));
+        return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::SessionNotCreated, ByteString::formatted("Failed to start session: {}", start_result.error()));
 
     auto& web_content_connection = session->web_content_connection();
 
@@ -160,7 +160,7 @@ Web::WebDriver::Response Client::new_session(Web::WebDriver::Parameters, JsonVal
     JsonObject body;
     // "sessionId"
     //     session id
-    body.set("sessionId", DeprecatedString::number(session_id));
+    body.set("sessionId", ByteString::number(session_id));
     // "capabilities"
     //     capabilities
     body.set("capabilities", move(capabilities));
@@ -323,7 +323,7 @@ Web::WebDriver::Response Client::switch_to_window(Web::WebDriver::Parameters par
     if (!handle.has_value())
         return Web::WebDriver::Error::from_code(Web::WebDriver::ErrorCode::InvalidArgument, "No property called 'handle' present");
 
-    return session->switch_to_window(handle->to_deprecated_string());
+    return session->switch_to_window(handle->to_byte_string());
 }
 
 // 11.4 Get Window Handles, https://w3c.github.io/webdriver/#dfn-get-window-handles
diff --git a/Userland/Services/WebDriver/Client.h b/Userland/Services/WebDriver/Client.h
index c9fa8ab09b1..4c30f169774 100644
--- a/Userland/Services/WebDriver/Client.h
+++ b/Userland/Services/WebDriver/Client.h
@@ -19,8 +19,8 @@
 namespace WebDriver {
 
 struct LaunchBrowserCallbacks {
-    Function<ErrorOr<pid_t>(DeprecatedString const&)> launch_browser;
-    Function<ErrorOr<pid_t>(DeprecatedString const&)> launch_headless_browser;
+    Function<ErrorOr<pid_t>(ByteString const&)> launch_browser;
+    Function<ErrorOr<pid_t>(ByteString const&)> launch_headless_browser;
 };
 
 class Client final : public Web::WebDriver::Client {
diff --git a/Userland/Services/WebDriver/Session.cpp b/Userland/Services/WebDriver/Session.cpp
index 9a8aab1fee9..f2d71dcc8c3 100644
--- a/Userland/Services/WebDriver/Session.cpp
+++ b/Userland/Services/WebDriver/Session.cpp
@@ -98,7 +98,7 @@ ErrorOr<void> Session::start(LaunchBrowserCallbacks const& callbacks)
 {
     auto promise = TRY(ServerPromise::try_create());
 
-    m_web_content_socket_path = DeprecatedString::formatted("{}/webdriver/session_{}_{}", TRY(Core::StandardPaths::runtime_directory()), getpid(), m_id);
+    m_web_content_socket_path = ByteString::formatted("{}/webdriver/session_{}_{}", TRY(Core::StandardPaths::runtime_directory()), getpid(), m_id);
     m_web_content_server = TRY(create_server(promise));
 
     if (m_options.headless)
diff --git a/Userland/Services/WebDriver/Session.h b/Userland/Services/WebDriver/Session.h
index 9b60177ba7c..8e983c3d36e 100644
--- a/Userland/Services/WebDriver/Session.h
+++ b/Userland/Services/WebDriver/Session.h
@@ -66,7 +66,7 @@ private:
     HashMap<String, Window> m_windows;
     String m_current_window_handle;
 
-    Optional<DeprecatedString> m_web_content_socket_path;
+    Optional<ByteString> m_web_content_socket_path;
     Optional<pid_t> m_browser_pid;
 
     RefPtr<Core::LocalServer> m_web_content_server;
diff --git a/Userland/Services/WebDriver/main.cpp b/Userland/Services/WebDriver/main.cpp
index b954c532279..746b8e7297e 100644
--- a/Userland/Services/WebDriver/main.cpp
+++ b/Userland/Services/WebDriver/main.cpp
@@ -14,7 +14,7 @@
 #include <LibMain/Main.h>
 #include <WebDriver/Client.h>
 
-static ErrorOr<pid_t> launch_browser(DeprecatedString const& socket_path)
+static ErrorOr<pid_t> launch_browser(ByteString const& socket_path)
 {
     return Core::Process::spawn("/bin/Browser"sv,
         Array {
@@ -24,7 +24,7 @@ static ErrorOr<pid_t> launch_browser(DeprecatedString const& socket_path)
         });
 }
 
-static ErrorOr<pid_t> launch_headless_browser(DeprecatedString const& socket_path)
+static ErrorOr<pid_t> launch_headless_browser(ByteString const& socket_path)
 {
     return Core::Process::spawn("/bin/headless-browser"sv,
         Array {
@@ -36,10 +36,10 @@ static ErrorOr<pid_t> launch_headless_browser(DeprecatedString const& socket_pat
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
-    DeprecatedString default_listen_address = "0.0.0.0";
+    ByteString default_listen_address = "0.0.0.0";
     u16 default_port = 8000;
 
-    DeprecatedString listen_address = default_listen_address;
+    ByteString listen_address = default_listen_address;
     int port = default_port;
 
     Core::ArgsParser args_parser;
@@ -60,7 +60,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     TRY(Core::System::pledge("stdio accept cpath rpath recvfd inet unix proc exec fattr"));
 
-    auto webdriver_socket_path = DeprecatedString::formatted("{}/webdriver", TRY(Core::StandardPaths::runtime_directory()));
+    auto webdriver_socket_path = ByteString::formatted("{}/webdriver", TRY(Core::StandardPaths::runtime_directory()));
     TRY(Core::Directory::create(webdriver_socket_path, Core::Directory::CreateDirectories::Yes));
 
     Core::EventLoop loop;
diff --git a/Userland/Services/WebServer/Client.cpp b/Userland/Services/WebServer/Client.cpp
index d2f66638855..961d1672134 100644
--- a/Userland/Services/WebServer/Client.cpp
+++ b/Userland/Services/WebServer/Client.cpp
@@ -79,7 +79,7 @@ ErrorOr<void, Client::WrappedError> Client::on_ready_to_read()
         return {};
 
     auto request = TRY(m_remaining_request.to_byte_buffer());
-    dbgln_if(WEBSERVER_DEBUG, "Got raw request: '{}'", DeprecatedString::copy(request));
+    dbgln_if(WEBSERVER_DEBUG, "Got raw request: '{}'", ByteString::copy(request));
 
     auto maybe_parsed_request = HTTP::HttpRequest::from_raw_request(TRY(m_remaining_request.to_byte_buffer()));
     if (maybe_parsed_request.is_error()) {
@@ -125,7 +125,7 @@ ErrorOr<bool> Client::handle_request(HTTP::HttpRequest const& request)
         }
     }
 
-    auto requested_path = TRY(String::from_deprecated_string(LexicalPath::join("/"sv, resource_decoded).string()));
+    auto requested_path = TRY(String::from_byte_string(LexicalPath::join("/"sv, resource_decoded).string()));
     dbgln_if(WEBSERVER_DEBUG, "Canonical requested path: '{}'", requested_path);
 
     auto real_path = TRY(String::formatted("{}{}", Configuration::the().document_root_path(), requested_path));
@@ -240,24 +240,24 @@ ErrorOr<void> Client::send_redirect(StringView redirect_path, HTTP::HttpRequest
     return {};
 }
 
-static DeprecatedString folder_image_data()
+static ByteString folder_image_data()
 {
-    static DeprecatedString cache;
+    static ByteString cache;
     if (cache.is_empty()) {
         auto file = Core::MappedFile::map("/res/icons/16x16/filetype-folder.png"sv).release_value_but_fixme_should_propagate_errors();
         // FIXME: change to TRY() and make method fallible
-        cache = MUST(encode_base64(file->bytes())).to_deprecated_string();
+        cache = MUST(encode_base64(file->bytes())).to_byte_string();
     }
     return cache;
 }
 
-static DeprecatedString file_image_data()
+static ByteString file_image_data()
 {
-    static DeprecatedString cache;
+    static ByteString cache;
     if (cache.is_empty()) {
         auto file = Core::MappedFile::map("/res/icons/16x16/filetype-unknown.png"sv).release_value_but_fixme_should_propagate_errors();
         // FIXME: change to TRY() and make method fallible
-        cache = MUST(encode_base64(file->bytes())).to_deprecated_string();
+        cache = MUST(encode_base64(file->bytes())).to_byte_string();
     }
     return cache;
 }
@@ -286,7 +286,7 @@ ErrorOr<void> Client::handle_directory_listing(String const& requested_path, Str
     TRY(builder.try_append("<code><table>\n"sv));
 
     Core::DirIterator dt(real_path.bytes_as_string_view());
-    Vector<DeprecatedString> names;
+    Vector<ByteString> names;
     while (dt.has_next())
         TRY(names.try_append(dt.next_path()));
     quick_sort(names);
@@ -337,7 +337,7 @@ ErrorOr<void> Client::handle_directory_listing(String const& requested_path, Str
     TRY(builder.try_append("</body>\n"sv));
     TRY(builder.try_append("</html>\n"sv));
 
-    auto response = builder.to_deprecated_string();
+    auto response = builder.to_byte_string();
     FixedMemoryStream stream { response.bytes() };
     return send_response(stream, request, { .type = "text/html"_string, .length = response.length() });
 }
@@ -373,7 +373,7 @@ ErrorOr<void> Client::send_error_response(unsigned code, HTTP::HttpRequest const
 
 void Client::log_response(unsigned code, HTTP::HttpRequest const& request)
 {
-    outln("{} :: {:03d} :: {} {}", Core::DateTime::now().to_deprecated_string(), code, request.method_name(), request.url().serialize().substring(1));
+    outln("{} :: {:03d} :: {} {}", Core::DateTime::now().to_byte_string(), code, request.method_name(), request.url().serialize().substring(1));
 }
 
 bool Client::verify_credentials(Vector<HTTP::HttpRequest::Header> const& headers)
diff --git a/Userland/Services/WebServer/Configuration.h b/Userland/Services/WebServer/Configuration.h
index 3cbbfee8a58..875d4ebbe84 100644
--- a/Userland/Services/WebServer/Configuration.h
+++ b/Userland/Services/WebServer/Configuration.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Optional.h>
 #include <LibHTTP/HttpRequest.h>
 
diff --git a/Userland/Services/WebServer/main.cpp b/Userland/Services/WebServer/main.cpp
index 6edc5be8150..f7f7b8c308f 100644
--- a/Userland/Services/WebServer/main.cpp
+++ b/Userland/Services/WebServer/main.cpp
@@ -26,11 +26,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     static auto const default_port = 8000;
     static auto const default_document_root_path = "/www"_string;
 
-    DeprecatedString listen_address = default_listen_address.to_deprecated_string();
+    ByteString listen_address = default_listen_address.to_byte_string();
     int port = default_port;
-    DeprecatedString username;
-    DeprecatedString password;
-    DeprecatedString document_root_path = default_document_root_path.to_deprecated_string();
+    ByteString username;
+    ByteString password;
+    ByteString document_root_path = default_document_root_path.to_byte_string();
 
     Core::ArgsParser args_parser;
     args_parser.add_option(listen_address, "IP address to listen on", "listen-address", 'l', "listen_address");
diff --git a/Userland/Services/WebSocket/ConnectionFromClient.cpp b/Userland/Services/WebSocket/ConnectionFromClient.cpp
index c679d867fe5..21135c6b123 100644
--- a/Userland/Services/WebSocket/ConnectionFromClient.cpp
+++ b/Userland/Services/WebSocket/ConnectionFromClient.cpp
@@ -26,8 +26,8 @@ void ConnectionFromClient::die()
         Core::EventLoop::current().quit(0);
 }
 
-Messages::WebSocketServer::ConnectResponse ConnectionFromClient::connect(URL const& url, DeprecatedString const& origin,
-    Vector<DeprecatedString> const& protocols, Vector<DeprecatedString> const& extensions, HashMap<DeprecatedString, DeprecatedString> const& additional_request_headers)
+Messages::WebSocketServer::ConnectResponse ConnectionFromClient::connect(URL const& url, ByteString const& origin,
+    Vector<ByteString> const& protocols, Vector<ByteString> const& extensions, HashMap<ByteString, ByteString> const& additional_request_headers)
 {
     if (!url.is_valid()) {
         dbgln("WebSocket::Connect: Invalid URL requested: '{}'", url);
@@ -57,7 +57,7 @@ Messages::WebSocketServer::ConnectResponse ConnectionFromClient::connect(URL con
     connection->on_error = [this, id](auto message) {
         did_error(id, (i32)message);
     };
-    connection->on_close = [this, id](u16 code, DeprecatedString reason, bool was_clean) {
+    connection->on_close = [this, id](u16 code, ByteString reason, bool was_clean) {
         did_close(id, code, move(reason), was_clean);
     };
 
@@ -81,7 +81,7 @@ Messages::WebSocketServer::SubprotocolInUseResponse ConnectionFromClient::subpro
     if (connection) {
         return connection->subprotocol_in_use();
     }
-    return DeprecatedString::empty();
+    return ByteString::empty();
 }
 
 void ConnectionFromClient::send(i32 connection_id, bool is_text, ByteBuffer const& data)
@@ -93,7 +93,7 @@ void ConnectionFromClient::send(i32 connection_id, bool is_text, ByteBuffer cons
     }
 }
 
-void ConnectionFromClient::close(i32 connection_id, u16 code, DeprecatedString const& reason)
+void ConnectionFromClient::close(i32 connection_id, u16 code, ByteString const& reason)
 {
     RefPtr<WebSocket> connection = m_connections.get(connection_id).value_or({});
     if (connection && connection->ready_state() == ReadyState::Open)
@@ -101,7 +101,7 @@ void ConnectionFromClient::close(i32 connection_id, u16 code, DeprecatedString c
 }
 
 Messages::WebSocketServer::SetCertificateResponse ConnectionFromClient::set_certificate(i32 connection_id,
-    [[maybe_unused]] DeprecatedString const& certificate, [[maybe_unused]] DeprecatedString const& key)
+    [[maybe_unused]] ByteString const& certificate, [[maybe_unused]] ByteString const& key)
 {
     RefPtr<WebSocket> connection = m_connections.get(connection_id).value_or({});
     bool success = false;
@@ -128,7 +128,7 @@ void ConnectionFromClient::did_error(i32 connection_id, i32 message)
     async_errored(connection_id, message);
 }
 
-void ConnectionFromClient::did_close(i32 connection_id, u16 code, DeprecatedString reason, bool was_clean)
+void ConnectionFromClient::did_close(i32 connection_id, u16 code, ByteString reason, bool was_clean)
 {
     async_closed(connection_id, code, reason, was_clean);
     deferred_invoke([this, connection_id] {
diff --git a/Userland/Services/WebSocket/ConnectionFromClient.h b/Userland/Services/WebSocket/ConnectionFromClient.h
index 04d77ed8bca..e8a8dd3c32b 100644
--- a/Userland/Services/WebSocket/ConnectionFromClient.h
+++ b/Userland/Services/WebSocket/ConnectionFromClient.h
@@ -26,17 +26,17 @@ public:
 private:
     explicit ConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>);
 
-    virtual Messages::WebSocketServer::ConnectResponse connect(URL const&, DeprecatedString const&, Vector<DeprecatedString> const&, Vector<DeprecatedString> const&, HashMap<DeprecatedString, DeprecatedString> const&) override;
+    virtual Messages::WebSocketServer::ConnectResponse connect(URL const&, ByteString const&, Vector<ByteString> const&, Vector<ByteString> const&, HashMap<ByteString, ByteString> const&) override;
     virtual Messages::WebSocketServer::ReadyStateResponse ready_state(i32) override;
     virtual Messages::WebSocketServer::SubprotocolInUseResponse subprotocol_in_use(i32) override;
     virtual void send(i32, bool, ByteBuffer const&) override;
-    virtual void close(i32, u16, DeprecatedString const&) override;
-    virtual Messages::WebSocketServer::SetCertificateResponse set_certificate(i32, DeprecatedString const&, DeprecatedString const&) override;
+    virtual void close(i32, u16, ByteString const&) override;
+    virtual Messages::WebSocketServer::SetCertificateResponse set_certificate(i32, ByteString const&, ByteString const&) override;
 
     void did_connect(i32);
     void did_receive_message(i32, Message);
     void did_error(i32, i32 message);
-    void did_close(i32, u16 code, DeprecatedString reason, bool was_clean);
+    void did_close(i32, u16 code, ByteString reason, bool was_clean);
     void did_request_certificates(i32);
 
     i32 m_connection_ids { 0 };
diff --git a/Userland/Services/WebSocket/WebSocketClient.ipc b/Userland/Services/WebSocket/WebSocketClient.ipc
index 838b26f3cf4..77a2929e242 100644
--- a/Userland/Services/WebSocket/WebSocketClient.ipc
+++ b/Userland/Services/WebSocket/WebSocketClient.ipc
@@ -6,7 +6,7 @@ endpoint WebSocketClient
     connected(i32 connection_id) =|
     received(i32 connection_id, bool is_text, ByteBuffer data) =|
     errored(i32 connection_id, i32 message) =|
-    closed(i32 connection_id, u16 code, DeprecatedString reason, bool clean) =|
+    closed(i32 connection_id, u16 code, ByteString reason, bool clean) =|
 
     // Certificate requests
     certificate_requested(i32 connection_id) =|
diff --git a/Userland/Services/WebSocket/WebSocketServer.ipc b/Userland/Services/WebSocket/WebSocketServer.ipc
index 9db54bc4277..66d4d6d9a0c 100644
--- a/Userland/Services/WebSocket/WebSocketServer.ipc
+++ b/Userland/Services/WebSocket/WebSocketServer.ipc
@@ -3,11 +3,11 @@
 endpoint WebSocketServer
 {
     // Connection API
-    connect(URL url, DeprecatedString origin, Vector<DeprecatedString> protocols, Vector<DeprecatedString> extensions, HashMap<DeprecatedString,DeprecatedString> additional_request_headers) => (i32 connection_id)
+    connect(URL url, ByteString origin, Vector<ByteString> protocols, Vector<ByteString> extensions, HashMap<ByteString,ByteString> additional_request_headers) => (i32 connection_id)
     ready_state(i32 connection_id) => (u32 ready_state)
-    subprotocol_in_use(i32 connection_id) => (DeprecatedString subprotocol_in_use)
+    subprotocol_in_use(i32 connection_id) => (ByteString subprotocol_in_use)
     send(i32 connection_id, bool is_text, ByteBuffer data) =|
-    close(i32 connection_id, u16 code, DeprecatedString reason) =|
+    close(i32 connection_id, u16 code, ByteString reason) =|
 
-    set_certificate(i32 connection_id, DeprecatedString certificate, DeprecatedString key) => (bool success)
+    set_certificate(i32 connection_id, ByteString certificate, ByteString key) => (bool success)
 }
diff --git a/Userland/Services/WindowServer/AppletManager.cpp b/Userland/Services/WindowServer/AppletManager.cpp
index b9f8074cabd..1fb0147a434 100644
--- a/Userland/Services/WindowServer/AppletManager.cpp
+++ b/Userland/Services/WindowServer/AppletManager.cpp
@@ -14,7 +14,7 @@
 namespace WindowServer {
 
 static AppletManager* s_the;
-Vector<DeprecatedString> order_vector;
+Vector<ByteString> order_vector;
 
 AppletManager::AppletManager()
 {
diff --git a/Userland/Services/WindowServer/Compositor.cpp b/Userland/Services/WindowServer/Compositor.cpp
index 90701b59d51..847c3483c81 100644
--- a/Userland/Services/WindowServer/Compositor.cpp
+++ b/Userland/Services/WindowServer/Compositor.cpp
@@ -33,7 +33,7 @@ Compositor& Compositor::the()
     return s_the;
 }
 
-static WallpaperMode mode_to_enum(DeprecatedString const& name)
+static WallpaperMode mode_to_enum(ByteString const& name)
 {
     if (name == "Tile")
         return WallpaperMode::Tile;
@@ -776,7 +776,7 @@ void Compositor::start_compose_async_timer()
     }
 }
 
-bool Compositor::set_background_color(DeprecatedString const& background_color)
+bool Compositor::set_background_color(ByteString const& background_color)
 {
     auto color = Color::from_string(background_color);
     if (!color.has_value())
@@ -795,7 +795,7 @@ bool Compositor::set_background_color(DeprecatedString const& background_color)
     return succeeded;
 }
 
-bool Compositor::set_wallpaper_mode(DeprecatedString const& mode)
+bool Compositor::set_wallpaper_mode(ByteString const& mode)
 {
     g_config->write_entry("Background", "Mode", mode);
     bool succeeded = !g_config->sync().is_error();
diff --git a/Userland/Services/WindowServer/Compositor.h b/Userland/Services/WindowServer/Compositor.h
index 0db0a4297ea..256ecd8fa66 100644
--- a/Userland/Services/WindowServer/Compositor.h
+++ b/Userland/Services/WindowServer/Compositor.h
@@ -103,9 +103,9 @@ public:
 
     void screen_resolution_changed();
 
-    bool set_background_color(DeprecatedString const& background_color);
+    bool set_background_color(ByteString const& background_color);
 
-    bool set_wallpaper_mode(DeprecatedString const& mode);
+    bool set_wallpaper_mode(ByteString const& mode);
 
     bool set_wallpaper(RefPtr<Gfx::Bitmap const>);
     RefPtr<Gfx::Bitmap const> wallpaper_bitmap() const { return m_wallpaper; }
diff --git a/Userland/Services/WindowServer/ConnectionFromClient.cpp b/Userland/Services/WindowServer/ConnectionFromClient.cpp
index 2ee52cd19a5..cfe0a8cf112 100644
--- a/Userland/Services/WindowServer/ConnectionFromClient.cpp
+++ b/Userland/Services/WindowServer/ConnectionFromClient.cpp
@@ -148,8 +148,8 @@ void ConnectionFromClient::add_menu(i32 window_id, i32 menu_id)
 }
 
 void ConnectionFromClient::add_menu_item(i32 menu_id, i32 identifier, i32 submenu_id,
-    DeprecatedString const& text, bool enabled, bool visible, bool checkable, bool checked, bool is_default,
-    DeprecatedString const& shortcut, Gfx::ShareableBitmap const& icon, bool exclusive)
+    ByteString const& text, bool enabled, bool visible, bool checkable, bool checked, bool is_default,
+    ByteString const& shortcut, Gfx::ShareableBitmap const& icon, bool exclusive)
 {
     auto it = m_menus.find(menu_id);
     if (it == m_menus.end()) {
@@ -193,8 +193,8 @@ void ConnectionFromClient::dismiss_menu(i32 menu_id)
 }
 
 void ConnectionFromClient::update_menu_item(i32 menu_id, i32 identifier, [[maybe_unused]] i32 submenu_id,
-    DeprecatedString const& text, bool enabled, bool visible, bool checkable, bool checked, bool is_default,
-    DeprecatedString const& shortcut, Gfx::ShareableBitmap const& icon)
+    ByteString const& text, bool enabled, bool visible, bool checkable, bool checked, bool is_default,
+    ByteString const& shortcut, Gfx::ShareableBitmap const& icon)
 {
     auto it = m_menus.find(menu_id);
     if (it == m_menus.end()) {
@@ -327,12 +327,12 @@ Messages::WindowServer::SetWallpaperResponse ConnectionFromClient::set_wallpaper
     return Compositor::the().set_wallpaper(bitmap.bitmap());
 }
 
-void ConnectionFromClient::set_background_color(DeprecatedString const& background_color)
+void ConnectionFromClient::set_background_color(ByteString const& background_color)
 {
     Compositor::the().set_background_color(background_color);
 }
 
-void ConnectionFromClient::set_wallpaper_mode(DeprecatedString const& mode)
+void ConnectionFromClient::set_wallpaper_mode(ByteString const& mode)
 {
     Compositor::the().set_wallpaper_mode(mode);
 }
@@ -344,7 +344,7 @@ Messages::WindowServer::GetWallpaperResponse ConnectionFromClient::get_wallpaper
 
 Messages::WindowServer::SetScreenLayoutResponse ConnectionFromClient::set_screen_layout(ScreenLayout const& screen_layout, bool save)
 {
-    DeprecatedString error_msg;
+    ByteString error_msg;
     bool success = WindowManager::the().set_screen_layout(ScreenLayout(screen_layout), save, error_msg);
     return { success, move(error_msg) };
 }
@@ -356,7 +356,7 @@ Messages::WindowServer::GetScreenLayoutResponse ConnectionFromClient::get_screen
 
 Messages::WindowServer::SaveScreenLayoutResponse ConnectionFromClient::save_screen_layout()
 {
-    DeprecatedString error_msg;
+    ByteString error_msg;
     bool success = WindowManager::the().save_screen_layout(error_msg);
     return { success, move(error_msg) };
 }
@@ -386,7 +386,7 @@ void ConnectionFromClient::show_screen_numbers(bool show)
         Compositor::the().decrement_show_screen_number({});
 }
 
-void ConnectionFromClient::set_window_title(i32 window_id, DeprecatedString const& title)
+void ConnectionFromClient::set_window_title(i32 window_id, ByteString const& title)
 {
     auto it = m_windows.find(window_id);
     if (it == m_windows.end()) {
@@ -478,7 +478,7 @@ Messages::WindowServer::SetWindowRectResponse ConnectionFromClient::set_window_r
         return nullptr;
     }
     if (rect.width() > INT16_MAX || rect.height() > INT16_MAX) {
-        did_misbehave(DeprecatedString::formatted("SetWindowRect: Bad window sizing(width={}, height={}), dimension exceeds INT16_MAX", rect.width(), rect.height()).characters());
+        did_misbehave(ByteString::formatted("SetWindowRect: Bad window sizing(width={}, height={}), dimension exceeds INT16_MAX", rect.width(), rect.height()).characters());
         return nullptr;
     }
 
@@ -616,7 +616,7 @@ void ConnectionFromClient::create_window(i32 window_id, i32 process_id, Gfx::Int
     bool fullscreen, bool frameless, bool forced_shadow,
     float alpha_hit_threshold, Gfx::IntSize base_size, Gfx::IntSize size_increment,
     Gfx::IntSize minimum_size, Optional<Gfx::IntSize> const& resize_aspect_ratio, i32 type, i32 mode,
-    DeprecatedString const& title, i32 parent_window_id, Gfx::IntRect const& launch_origin_rect)
+    ByteString const& title, i32 parent_window_id, Gfx::IntRect const& launch_origin_rect)
 {
     Window* parent_window = nullptr;
     if (parent_window_id) {
@@ -871,7 +871,7 @@ void ConnectionFromClient::start_window_resize(i32 window_id, i32 resize_directi
     WindowManager::the().start_window_resize(window, ScreenInput::the().cursor_location(), MouseButton::Primary, (ResizeDirection)resize_direction);
 }
 
-Messages::WindowServer::StartDragResponse ConnectionFromClient::start_drag(DeprecatedString const& text, HashMap<String, ByteBuffer> const& mime_data, Gfx::ShareableBitmap const& drag_bitmap)
+Messages::WindowServer::StartDragResponse ConnectionFromClient::start_drag(ByteString const& text, HashMap<String, ByteBuffer> const& mime_data, Gfx::ShareableBitmap const& drag_bitmap)
 {
     auto& wm = WindowManager::the();
     if (wm.dnd_client() || !(wm.last_processed_buttons() & MouseButton::Primary))
@@ -888,7 +888,7 @@ void ConnectionFromClient::set_accepts_drag(bool accepts)
     wm.set_accepts_drag(accepts);
 }
 
-Messages::WindowServer::SetSystemThemeResponse ConnectionFromClient::set_system_theme(DeprecatedString const& theme_path, DeprecatedString const& theme_name, bool keep_desktop_background, Optional<DeprecatedString> const& color_scheme_path)
+Messages::WindowServer::SetSystemThemeResponse ConnectionFromClient::set_system_theme(ByteString const& theme_path, ByteString const& theme_name, bool keep_desktop_background, Optional<ByteString> const& color_scheme_path)
 {
     bool success = WindowManager::the().update_theme(theme_path, theme_name, keep_desktop_background, color_scheme_path);
     return success;
@@ -925,7 +925,7 @@ Messages::WindowServer::GetPreferredColorSchemeResponse ConnectionFromClient::ge
     return WindowManager::the().get_preferred_color_scheme();
 }
 
-void ConnectionFromClient::apply_cursor_theme(DeprecatedString const& name)
+void ConnectionFromClient::apply_cursor_theme(ByteString const& name)
 {
     WindowManager::the().apply_cursor_theme(name);
 }
@@ -955,7 +955,7 @@ Messages::WindowServer::GetCursorThemeResponse ConnectionFromClient::get_cursor_
     return g_config->read_entry("Mouse", "CursorTheme");
 }
 
-Messages::WindowServer::SetSystemFontsResponse ConnectionFromClient::set_system_fonts(DeprecatedString const& default_font_query, DeprecatedString const& fixed_width_font_query, DeprecatedString const& window_title_font_query)
+Messages::WindowServer::SetSystemFontsResponse ConnectionFromClient::set_system_fonts(ByteString const& default_font_query, ByteString const& fixed_width_font_query, ByteString const& window_title_font_query)
 {
     if (!Gfx::FontDatabase::the().get_by_name(default_font_query)
         || !Gfx::FontDatabase::the().get_by_name(fixed_width_font_query)) {
diff --git a/Userland/Services/WindowServer/ConnectionFromClient.h b/Userland/Services/WindowServer/ConnectionFromClient.h
index 37e44d217b7..ef70c71c8d7 100644
--- a/Userland/Services/WindowServer/ConnectionFromClient.h
+++ b/Userland/Services/WindowServer/ConnectionFromClient.h
@@ -97,16 +97,16 @@ private:
     virtual void set_menu_name(i32, String const&) override;
     virtual void destroy_menu(i32) override;
     virtual void add_menu(i32, i32) override;
-    virtual void add_menu_item(i32, i32, i32, DeprecatedString const&, bool, bool, bool, bool, bool, DeprecatedString const&, Gfx::ShareableBitmap const&, bool) override;
+    virtual void add_menu_item(i32, i32, i32, ByteString const&, bool, bool, bool, bool, bool, ByteString const&, Gfx::ShareableBitmap const&, bool) override;
     virtual void add_menu_separator(i32) override;
-    virtual void update_menu_item(i32, i32, i32, DeprecatedString const&, bool, bool, bool, bool, bool, DeprecatedString const&, Gfx::ShareableBitmap const&) override;
+    virtual void update_menu_item(i32, i32, i32, ByteString const&, bool, bool, bool, bool, bool, ByteString const&, Gfx::ShareableBitmap const&) override;
     virtual void remove_menu_item(i32 menu_id, i32 identifier) override;
     virtual void flash_menubar_menu(i32, i32) override;
     virtual void create_window(i32, i32, Gfx::IntRect const&, bool, bool, bool,
         bool, bool, bool, bool, bool, float, Gfx::IntSize, Gfx::IntSize, Gfx::IntSize,
-        Optional<Gfx::IntSize> const&, i32, i32, DeprecatedString const&, i32, Gfx::IntRect const&) override;
+        Optional<Gfx::IntSize> const&, i32, i32, ByteString const&, i32, Gfx::IntRect const&) override;
     virtual Messages::WindowServer::DestroyWindowResponse destroy_window(i32) override;
-    virtual void set_window_title(i32, DeprecatedString const&) override;
+    virtual void set_window_title(i32, ByteString const&) override;
     virtual Messages::WindowServer::GetWindowTitleResponse get_window_title(i32) override;
     virtual Messages::WindowServer::IsMaximizedResponse is_maximized(i32) override;
     virtual void set_maximized(i32, bool) override;
@@ -130,8 +130,8 @@ private:
     virtual void set_frameless(i32, bool) override;
     virtual void set_forced_shadow(i32, bool) override;
     virtual Messages::WindowServer::SetWallpaperResponse set_wallpaper(Gfx::ShareableBitmap const&) override;
-    virtual void set_background_color(DeprecatedString const&) override;
-    virtual void set_wallpaper_mode(DeprecatedString const&) override;
+    virtual void set_background_color(ByteString const&) override;
+    virtual void set_wallpaper_mode(ByteString const&) override;
     virtual Messages::WindowServer::GetWallpaperResponse get_wallpaper() override;
     virtual Messages::WindowServer::SetScreenLayoutResponse set_screen_layout(ScreenLayout const&, bool) override;
     virtual Messages::WindowServer::GetScreenLayoutResponse get_screen_layout() override;
@@ -144,22 +144,22 @@ private:
     virtual void popup_menu(i32, Gfx::IntPoint, Gfx::IntRect const&) override;
     virtual void dismiss_menu(i32) override;
     virtual void set_window_icon_bitmap(i32, Gfx::ShareableBitmap const&) override;
-    virtual Messages::WindowServer::StartDragResponse start_drag(DeprecatedString const&, HashMap<String, ByteBuffer> const&, Gfx::ShareableBitmap const&) override;
+    virtual Messages::WindowServer::StartDragResponse start_drag(ByteString const&, HashMap<String, ByteBuffer> const&, Gfx::ShareableBitmap const&) override;
     virtual void set_accepts_drag(bool) override;
-    virtual Messages::WindowServer::SetSystemThemeResponse set_system_theme(DeprecatedString const&, DeprecatedString const&, bool keep_desktop_background, Optional<DeprecatedString> const& color_scheme_path) override;
+    virtual Messages::WindowServer::SetSystemThemeResponse set_system_theme(ByteString const&, ByteString const&, bool keep_desktop_background, Optional<ByteString> const& color_scheme_path) override;
     virtual Messages::WindowServer::GetSystemThemeResponse get_system_theme() override;
     virtual Messages::WindowServer::SetSystemThemeOverrideResponse set_system_theme_override(Core::AnonymousBuffer const&) override;
     virtual Messages::WindowServer::GetSystemThemeOverrideResponse get_system_theme_override() override;
     virtual void clear_system_theme_override() override;
     virtual Messages::WindowServer::IsSystemThemeOverriddenResponse is_system_theme_overridden() override;
     virtual Messages::WindowServer::GetPreferredColorSchemeResponse get_preferred_color_scheme() override;
-    virtual void apply_cursor_theme(DeprecatedString const&) override;
+    virtual void apply_cursor_theme(ByteString const&) override;
     virtual void set_cursor_highlight_radius(int radius) override;
     virtual Messages::WindowServer::GetCursorHighlightRadiusResponse get_cursor_highlight_radius() override;
     virtual void set_cursor_highlight_color(Gfx::Color color) override;
     virtual Messages::WindowServer::GetCursorHighlightColorResponse get_cursor_highlight_color() override;
     virtual Messages::WindowServer::GetCursorThemeResponse get_cursor_theme() override;
-    virtual Messages::WindowServer::SetSystemFontsResponse set_system_fonts(DeprecatedString const&, DeprecatedString const&, DeprecatedString const&) override;
+    virtual Messages::WindowServer::SetSystemFontsResponse set_system_fonts(ByteString const&, ByteString const&, ByteString const&) override;
     virtual void set_system_effects(Vector<bool> const&, u8, u8) override;
     virtual void set_window_base_size_and_size_increment(i32, Gfx::IntSize, Gfx::IntSize) override;
     virtual void set_window_resize_aspect_ratio(i32, Optional<Gfx::IntSize> const&) override;
diff --git a/Userland/Services/WindowServer/Event.h b/Userland/Services/WindowServer/Event.h
index b736dea2938..465a8123d07 100644
--- a/Userland/Services/WindowServer/Event.h
+++ b/Userland/Services/WindowServer/Event.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <Kernel/API/KeyCode.h>
 #include <LibCore/Event.h>
 #include <LibCore/MimeData.h>
diff --git a/Userland/Services/WindowServer/HardwareScreenBackend.cpp b/Userland/Services/WindowServer/HardwareScreenBackend.cpp
index 4a421a346d8..51c9b52ceec 100644
--- a/Userland/Services/WindowServer/HardwareScreenBackend.cpp
+++ b/Userland/Services/WindowServer/HardwareScreenBackend.cpp
@@ -17,7 +17,7 @@
 
 namespace WindowServer {
 
-HardwareScreenBackend::HardwareScreenBackend(DeprecatedString device)
+HardwareScreenBackend::HardwareScreenBackend(ByteString device)
     : m_device(move(device))
 {
 }
@@ -28,7 +28,7 @@ ErrorOr<void> HardwareScreenBackend::open()
 
     GraphicsConnectorProperties properties;
     if (graphics_connector_get_properties(m_display_connector_fd, &properties) < 0)
-        return Error::from_syscall(DeprecatedString::formatted("failed to ioctl {}", m_device), errno);
+        return Error::from_syscall(ByteString::formatted("failed to ioctl {}", m_device), errno);
 
     m_can_device_flush_buffers = (properties.partial_flushing_support != 0);
     m_can_device_flush_entire_framebuffer = (properties.flushing_support != 0);
diff --git a/Userland/Services/WindowServer/HardwareScreenBackend.h b/Userland/Services/WindowServer/HardwareScreenBackend.h
index d72ffc890bb..bccaccff1ba 100644
--- a/Userland/Services/WindowServer/HardwareScreenBackend.h
+++ b/Userland/Services/WindowServer/HardwareScreenBackend.h
@@ -8,7 +8,7 @@
 
 #include "ScreenBackend.h"
 #include "ScreenLayout.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Span.h>
 #include <sys/ioctl.h>
@@ -18,7 +18,7 @@ class HardwareScreenBackend : public ScreenBackend {
 public:
     virtual ~HardwareScreenBackend();
 
-    explicit HardwareScreenBackend(DeprecatedString device);
+    explicit HardwareScreenBackend(ByteString device);
 
     virtual ErrorOr<void> open() override;
 
@@ -36,7 +36,7 @@ public:
     virtual ErrorOr<void> set_head_mode_setting(GraphicsHeadModeSetting) override;
     virtual ErrorOr<GraphicsHeadModeSetting> get_head_mode_setting() override;
 
-    DeprecatedString m_device {};
+    ByteString m_device {};
     int m_display_connector_fd { -1 };
 
     Gfx::ARGB32* scanline(int buffer_index, int y) const
diff --git a/Userland/Services/WindowServer/KeymapSwitcher.cpp b/Userland/Services/WindowServer/KeymapSwitcher.cpp
index 161ee3f59f4..f5f66be80c0 100644
--- a/Userland/Services/WindowServer/KeymapSwitcher.cpp
+++ b/Userland/Services/WindowServer/KeymapSwitcher.cpp
@@ -87,17 +87,17 @@ void KeymapSwitcher::next_keymap()
     }
 }
 
-DeprecatedString KeymapSwitcher::get_current_keymap() const
+ByteString KeymapSwitcher::get_current_keymap() const
 {
     auto proc_keymap = Core::File::open("/sys/kernel/keymap"sv, Core::File::OpenMode::Read).release_value_but_fixme_should_propagate_errors();
     auto proc_keymap_data = proc_keymap->read_until_eof().release_value_but_fixme_should_propagate_errors();
     auto json = JsonValue::from_string(proc_keymap_data).release_value_but_fixme_should_propagate_errors();
     auto const& keymap_object = json.as_object();
     VERIFY(keymap_object.has_string("keymap"sv));
-    return keymap_object.get_deprecated_string("keymap"sv).value();
+    return keymap_object.get_byte_string("keymap"sv).value();
 }
 
-void KeymapSwitcher::set_keymap(const AK::DeprecatedString& keymap)
+void KeymapSwitcher::set_keymap(const AK::ByteString& keymap)
 {
     if (Core::Process::spawn("/bin/keymap"sv, Array { "-m", keymap.characters() }).is_error())
         dbgln("Failed to call /bin/keymap, error: {} ({})", errno, strerror(errno));
diff --git a/Userland/Services/WindowServer/KeymapSwitcher.h b/Userland/Services/WindowServer/KeymapSwitcher.h
index 92c2e4ca1e3..01f4d596ea4 100644
--- a/Userland/Services/WindowServer/KeymapSwitcher.h
+++ b/Userland/Services/WindowServer/KeymapSwitcher.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <AK/WeakPtr.h>
 #include <LibCore/EventReceiver.h>
@@ -23,18 +23,18 @@ public:
 
     void next_keymap();
 
-    Function<void(DeprecatedString const& keymap)> on_keymap_change;
+    Function<void(ByteString const& keymap)> on_keymap_change;
 
-    DeprecatedString get_current_keymap() const;
+    ByteString get_current_keymap() const;
 
-    void set_keymap(AK::DeprecatedString const&);
+    void set_keymap(AK::ByteString const&);
 
 private:
     void refresh();
 
     KeymapSwitcher();
 
-    Vector<AK::DeprecatedString> m_keymaps;
+    Vector<AK::ByteString> m_keymaps;
 
     RefPtr<Core::FileWatcher> m_file_watcher;
 
diff --git a/Userland/Services/WindowServer/Menu.h b/Userland/Services/WindowServer/Menu.h
index 54c79db4bf4..5b3a76171df 100644
--- a/Userland/Services/WindowServer/Menu.h
+++ b/Userland/Services/WindowServer/Menu.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/WeakPtr.h>
 #include <LibCore/EventReceiver.h>
 #include <LibGfx/Font/Font.h>
diff --git a/Userland/Services/WindowServer/MenuItem.cpp b/Userland/Services/WindowServer/MenuItem.cpp
index e6a1c213adf..7e0963afe4e 100644
--- a/Userland/Services/WindowServer/MenuItem.cpp
+++ b/Userland/Services/WindowServer/MenuItem.cpp
@@ -12,7 +12,7 @@
 
 namespace WindowServer {
 
-MenuItem::MenuItem(Menu& menu, unsigned identifier, DeprecatedString const& text, DeprecatedString const& shortcut_text, bool enabled, bool visible, bool checkable, bool checked, Gfx::Bitmap const* icon)
+MenuItem::MenuItem(Menu& menu, unsigned identifier, ByteString const& text, ByteString const& shortcut_text, bool enabled, bool visible, bool checkable, bool checked, Gfx::Bitmap const* icon)
     : m_menu(menu)
     , m_type(Text)
     , m_enabled(enabled)
diff --git a/Userland/Services/WindowServer/MenuItem.h b/Userland/Services/WindowServer/MenuItem.h
index adb0d0a479f..bec0cbb3ecd 100644
--- a/Userland/Services/WindowServer/MenuItem.h
+++ b/Userland/Services/WindowServer/MenuItem.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <LibGfx/Forward.h>
 #include <LibGfx/Rect.h>
@@ -23,7 +23,7 @@ public:
         Separator,
     };
 
-    MenuItem(Menu&, unsigned identifier, DeprecatedString const& text, DeprecatedString const& shortcut_text = {}, bool enabled = true, bool visible = true, bool checkable = false, bool checked = false, Gfx::Bitmap const* icon = nullptr);
+    MenuItem(Menu&, unsigned identifier, ByteString const& text, ByteString const& shortcut_text = {}, bool enabled = true, bool visible = true, bool checkable = false, bool checked = false, Gfx::Bitmap const* icon = nullptr);
     MenuItem(Menu&, Type);
     ~MenuItem() = default;
 
@@ -44,11 +44,11 @@ public:
     bool is_default() const { return m_default; }
     void set_default(bool);
 
-    DeprecatedString text() const { return m_text; }
-    void set_text(DeprecatedString text) { m_text = move(text); }
+    ByteString text() const { return m_text; }
+    void set_text(ByteString text) { m_text = move(text); }
 
-    DeprecatedString shortcut_text() const { return m_shortcut_text; }
-    void set_shortcut_text(DeprecatedString text) { m_shortcut_text = move(text); }
+    ByteString shortcut_text() const { return m_shortcut_text; }
+    void set_shortcut_text(ByteString text) { m_shortcut_text = move(text); }
 
     void set_rect(Gfx::IntRect const& rect) { m_rect = rect; }
     Gfx::IntRect rect() const;
@@ -77,8 +77,8 @@ private:
     bool m_checked { false };
     bool m_default { false };
     unsigned m_identifier { 0 };
-    DeprecatedString m_text;
-    DeprecatedString m_shortcut_text;
+    ByteString m_text;
+    ByteString m_shortcut_text;
     Gfx::IntRect m_rect;
     RefPtr<Gfx::Bitmap const> m_icon;
     int m_submenu_id { -1 };
diff --git a/Userland/Services/WindowServer/Overlays.cpp b/Userland/Services/WindowServer/Overlays.cpp
index 7f09445827f..0a89e67f334 100644
--- a/Userland/Services/WindowServer/Overlays.cpp
+++ b/Userland/Services/WindowServer/Overlays.cpp
@@ -170,7 +170,7 @@ void ScreenNumberOverlay::pick_font()
     auto screen_number_content_rect_size = calculate_content_rect_for_screen(Screen::main()).size();
     auto& font_database = Gfx::FontDatabase::the();
     auto& default_font = WindowManager::the().font();
-    DeprecatedString best_font_name;
+    ByteString best_font_name;
     int best_font_size = -1;
     font_database.for_each_font([&](Gfx::Font const& font) {
         // TODO: instead of picking *any* font we should probably compare font.name()
@@ -183,7 +183,7 @@ void ScreenNumberOverlay::pick_font()
                     return;
                 }
             }
-            best_font_name = font.qualified_name().to_deprecated_string();
+            best_font_name = font.qualified_name().to_byte_string();
             best_font_size = size;
         }
     });
@@ -212,7 +212,7 @@ Gfx::Font const& ScreenNumberOverlay::font()
 
 void ScreenNumberOverlay::render_overlay_bitmap(Gfx::Painter& painter)
 {
-    painter.draw_text(Gfx::IntRect { {}, rect().size() }, DeprecatedString::formatted("{}", m_screen.index() + 1), font(), Gfx::TextAlignment::Center, Color::White);
+    painter.draw_text(Gfx::IntRect { {}, rect().size() }, ByteString::formatted("{}", m_screen.index() + 1), font(), Gfx::TextAlignment::Center, Color::White);
 }
 
 Gfx::IntRect ScreenNumberOverlay::calculate_content_rect_for_screen(Screen& screen)
@@ -319,9 +319,9 @@ void WindowGeometryOverlay::window_rect_changed()
             if (!window->size_increment().is_empty()) {
                 int width_steps = (window->width() - window->base_size().width()) / window->size_increment().width();
                 int height_steps = (window->height() - window->base_size().height()) / window->size_increment().height();
-                m_label = DeprecatedString::formatted("{} ({}x{})", geometry_rect, width_steps, height_steps);
+                m_label = ByteString::formatted("{} ({}x{})", geometry_rect, width_steps, height_steps);
             } else {
-                m_label = geometry_rect.to_deprecated_string();
+                m_label = geometry_rect.to_byte_string();
             }
             m_label_rect = Gfx::IntRect { 0, 0, static_cast<int>(ceilf(wm.font().width(m_label))) + 16, wm.font().pixel_size_rounded_up() + 10 };
 
@@ -341,7 +341,7 @@ void WindowGeometryOverlay::render_overlay_bitmap(Gfx::Painter& painter)
     painter.draw_text(Gfx::IntRect { {}, rect().size() }, m_label, WindowManager::the().font(), Gfx::TextAlignment::Center, Color::White);
 }
 
-DndOverlay::DndOverlay(DeprecatedString const& text, Gfx::Bitmap const* bitmap)
+DndOverlay::DndOverlay(ByteString const& text, Gfx::Bitmap const* bitmap)
     : m_bitmap(bitmap)
     , m_text(text)
 {
diff --git a/Userland/Services/WindowServer/Overlays.h b/Userland/Services/WindowServer/Overlays.h
index aae30db077a..b9d2a8cdafa 100644
--- a/Userland/Services/WindowServer/Overlays.h
+++ b/Userland/Services/WindowServer/Overlays.h
@@ -154,7 +154,7 @@ private:
     Gfx::IntRect calculate_ideal_overlay_rect() const;
 
     WeakPtr<Window> m_window;
-    DeprecatedString m_label;
+    ByteString m_label;
     Gfx::IntRect m_label_rect;
     Gfx::IntRect m_ideal_overlay_rect;
 
@@ -182,7 +182,7 @@ private:
 
 class DndOverlay : public BitmapOverlay {
 public:
-    DndOverlay(DeprecatedString const&, Gfx::Bitmap const*);
+    DndOverlay(ByteString const&, Gfx::Bitmap const*);
 
     void cursor_moved()
     {
@@ -197,7 +197,7 @@ private:
     void update_rect();
 
     RefPtr<Gfx::Bitmap const> m_bitmap;
-    DeprecatedString m_text;
+    ByteString m_text;
     Gfx::IntRect m_label_rect;
 };
 
diff --git a/Userland/Services/WindowServer/Screen.cpp b/Userland/Services/WindowServer/Screen.cpp
index 895155b22ed..1e055074fc3 100644
--- a/Userland/Services/WindowServer/Screen.cpp
+++ b/Userland/Services/WindowServer/Screen.cpp
@@ -54,7 +54,7 @@ Screen const& ScreenInput::cursor_location_screen() const
     return *screen;
 }
 
-bool Screen::apply_layout(ScreenLayout&& screen_layout, DeprecatedString& error_msg)
+bool Screen::apply_layout(ScreenLayout&& screen_layout, ByteString& error_msg)
 {
     if (!screen_layout.is_valid(&error_msg))
         return false;
@@ -145,7 +145,7 @@ bool Screen::apply_layout(ScreenLayout&& screen_layout, DeprecatedString& error_
         } else {
             screen = WindowServer::Screen::create(index);
             if (!screen) {
-                error_msg = DeprecatedString::formatted("Error creating screen #{}", index);
+                error_msg = ByteString::formatted("Error creating screen #{}", index);
                 return false;
             }
 
@@ -153,7 +153,7 @@ bool Screen::apply_layout(ScreenLayout&& screen_layout, DeprecatedString& error_
         }
 
         if (need_to_open_device && !screen->open_device()) {
-            error_msg = DeprecatedString::formatted("Error opening device for screen #{}", index);
+            error_msg = ByteString::formatted("Error opening device for screen #{}", index);
             return false;
         }
 
diff --git a/Userland/Services/WindowServer/Screen.h b/Userland/Services/WindowServer/Screen.h
index f4868076045..11b2d7f73b7 100644
--- a/Userland/Services/WindowServer/Screen.h
+++ b/Userland/Services/WindowServer/Screen.h
@@ -81,7 +81,7 @@ public:
     }
     ~Screen();
 
-    static bool apply_layout(ScreenLayout&&, DeprecatedString&);
+    static bool apply_layout(ScreenLayout&&, ByteString&);
     static ScreenLayout const& layout() { return s_layout; }
 
     static Screen& main()
diff --git a/Userland/Services/WindowServer/ScreenLayout.h b/Userland/Services/WindowServer/ScreenLayout.h
index 4ff2d5bcf87..b43af099fd9 100644
--- a/Userland/Services/WindowServer/ScreenLayout.h
+++ b/Userland/Services/WindowServer/ScreenLayout.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <LibCore/ConfigFile.h>
 #include <LibGfx/Rect.h>
@@ -23,7 +23,7 @@ public:
             Device,
             Virtual,
         } mode;
-        Optional<DeprecatedString> device;
+        Optional<ByteString> device;
         Gfx::IntPoint location;
         Gfx::IntSize resolution;
         int scale_factor;
@@ -55,11 +55,11 @@ public:
     Vector<Screen> screens;
     unsigned main_screen_index { 0 };
 
-    bool is_valid(DeprecatedString* error_msg = nullptr) const;
+    bool is_valid(ByteString* error_msg = nullptr) const;
     bool normalize();
-    bool load_config(Core::ConfigFile const& config_file, DeprecatedString* error_msg = nullptr);
+    bool load_config(Core::ConfigFile const& config_file, ByteString* error_msg = nullptr);
     bool save_config(Core::ConfigFile& config_file, bool sync = true) const;
-    bool try_auto_add_display_connector(DeprecatedString const&);
+    bool try_auto_add_display_connector(ByteString const&);
 
     // TODO: spaceship operator
     bool operator!=(ScreenLayout const& other) const;
diff --git a/Userland/Services/WindowServer/ScreenLayout.ipp b/Userland/Services/WindowServer/ScreenLayout.ipp
index 4f718b76320..ae1f7107f77 100644
--- a/Userland/Services/WindowServer/ScreenLayout.ipp
+++ b/Userland/Services/WindowServer/ScreenLayout.ipp
@@ -15,7 +15,7 @@
 
 namespace WindowServer {
 
-bool ScreenLayout::is_valid(DeprecatedString* error_msg) const
+bool ScreenLayout::is_valid(ByteString* error_msg) const
 {
     if (screens.is_empty()) {
         if (error_msg)
@@ -24,7 +24,7 @@ bool ScreenLayout::is_valid(DeprecatedString* error_msg) const
     }
     if (main_screen_index >= screens.size()) {
         if (error_msg)
-            *error_msg = DeprecatedString::formatted("Invalid main screen index: {}", main_screen_index);
+            *error_msg = ByteString::formatted("Invalid main screen index: {}", main_screen_index);
         return false;
     }
     int smallest_x = 0;
@@ -33,7 +33,7 @@ bool ScreenLayout::is_valid(DeprecatedString* error_msg) const
         auto& screen = screens[i];
         if (screen.mode == Screen::Mode::Device && screen.device->is_empty()) {
             if (error_msg)
-                *error_msg = DeprecatedString::formatted("Screen #{} has no path", i);
+                *error_msg = ByteString::formatted("Screen #{} has no path", i);
             return false;
         }
         for (size_t j = 0; j < screens.size(); j++) {
@@ -42,28 +42,28 @@ bool ScreenLayout::is_valid(DeprecatedString* error_msg) const
                 continue;
             if (screen.device == other_screen.device) {
                 if (error_msg)
-                    *error_msg = DeprecatedString::formatted("Screen #{} is using same device as screen #{}", i, j);
+                    *error_msg = ByteString::formatted("Screen #{} is using same device as screen #{}", i, j);
                 return false;
             }
             if (screen.virtual_rect().intersects(other_screen.virtual_rect())) {
                 if (error_msg)
-                    *error_msg = DeprecatedString::formatted("Screen #{} overlaps with screen #{}", i, j);
+                    *error_msg = ByteString::formatted("Screen #{} overlaps with screen #{}", i, j);
                 return false;
             }
         }
         if (screen.location.x() < 0 || screen.location.y() < 0) {
             if (error_msg)
-                *error_msg = DeprecatedString::formatted("Screen #{} has invalid location: {}", i, screen.location);
+                *error_msg = ByteString::formatted("Screen #{} has invalid location: {}", i, screen.location);
             return false;
         }
         if (screen.resolution.width() <= 0 || screen.resolution.height() <= 0) {
             if (error_msg)
-                *error_msg = DeprecatedString::formatted("Screen #{} has invalid resolution: {}", i, screen.resolution);
+                *error_msg = ByteString::formatted("Screen #{} has invalid resolution: {}", i, screen.resolution);
             return false;
         }
         if (screen.scale_factor < 1) {
             if (error_msg)
-                *error_msg = DeprecatedString::formatted("Screen #{} has invalid scale factor: {}", i, screen.scale_factor);
+                *error_msg = ByteString::formatted("Screen #{} has invalid scale factor: {}", i, screen.scale_factor);
             return false;
         }
         if (i == 0 || screen.location.x() < smallest_x)
@@ -96,7 +96,7 @@ bool ScreenLayout::is_valid(DeprecatedString* error_msg) const
             auto& screen = screens[i];
             if (!reachable_screens.contains_slow(&screen)) {
                 if (error_msg)
-                    *error_msg = DeprecatedString::formatted("Screen #{} {} cannot be reached from main screen #{} {}", i, screen.virtual_rect(), main_screen_index, screens[main_screen_index].virtual_rect());
+                    *error_msg = ByteString::formatted("Screen #{} {} cannot be reached from main screen #{} {}", i, screen.virtual_rect(), main_screen_index, screens[main_screen_index].virtual_rect());
                 break;
             }
         }
@@ -225,12 +225,12 @@ bool ScreenLayout::normalize()
     return did_change;
 }
 
-bool ScreenLayout::load_config(Core::ConfigFile const& config_file, DeprecatedString* error_msg)
+bool ScreenLayout::load_config(Core::ConfigFile const& config_file, ByteString* error_msg)
 {
     screens.clear_with_capacity();
     main_screen_index = config_file.read_num_entry("Screens", "MainScreen", 0);
     for (size_t index = 0;; index++) {
-        auto group_name = DeprecatedString::formatted("Screen{}", index);
+        auto group_name = ByteString::formatted("Screen{}", index);
         if (!config_file.has_group(group_name))
             break;
         auto str_mode = config_file.read_entry(group_name, "Mode");
@@ -242,11 +242,11 @@ bool ScreenLayout::load_config(Core::ConfigFile const& config_file, DeprecatedSt
         }
 
         if (mode == Screen::Mode::Invalid) {
-            *error_msg = DeprecatedString::formatted("Invalid screen mode '{}'", str_mode);
+            *error_msg = ByteString::formatted("Invalid screen mode '{}'", str_mode);
             *this = {};
             return false;
         }
-        auto device = (mode == Screen::Mode::Device) ? config_file.read_entry(group_name, "Device") : Optional<DeprecatedString> {};
+        auto device = (mode == Screen::Mode::Device) ? config_file.read_entry(group_name, "Device") : Optional<ByteString> {};
         screens.append({ mode, device,
             { config_file.read_num_entry(group_name, "Left"), config_file.read_num_entry(group_name, "Top") },
             { config_file.read_num_entry(group_name, "Width"), config_file.read_num_entry(group_name, "Height") },
@@ -266,7 +266,7 @@ bool ScreenLayout::save_config(Core::ConfigFile& config_file, bool sync) const
     size_t index = 0;
     while (index < screens.size()) {
         auto& screen = screens[index];
-        auto group_name = DeprecatedString::formatted("Screen{}", index);
+        auto group_name = ByteString::formatted("Screen{}", index);
         config_file.write_entry(group_name, "Mode", Screen::mode_to_string(screen.mode));
         if (screen.mode == Screen::Mode::Device)
             config_file.write_entry(group_name, "Device", screen.device.value());
@@ -279,7 +279,7 @@ bool ScreenLayout::save_config(Core::ConfigFile& config_file, bool sync) const
     }
     // Prune screens no longer in the layout
     for (;;) {
-        auto group_name = DeprecatedString::formatted("Screen{}", index++);
+        auto group_name = ByteString::formatted("Screen{}", index++);
         if (!config_file.has_group(group_name))
             break;
         config_file.remove_group(group_name);
@@ -305,7 +305,7 @@ bool ScreenLayout::operator!=(ScreenLayout const& other) const
     return false;
 }
 
-bool ScreenLayout::try_auto_add_display_connector(DeprecatedString const& device_path)
+bool ScreenLayout::try_auto_add_display_connector(ByteString const& device_path)
 {
     int display_connector_fd = open(device_path.characters(), O_RDWR | O_CLOEXEC);
     if (display_connector_fd < 0) {
@@ -408,7 +408,7 @@ template<>
 ErrorOr<WindowServer::ScreenLayout::Screen> decode(Decoder& decoder)
 {
     auto mode = TRY(decoder.decode<WindowServer::ScreenLayout::Screen::Mode>());
-    auto device = TRY(decoder.decode<Optional<DeprecatedString>>());
+    auto device = TRY(decoder.decode<Optional<ByteString>>());
     auto location = TRY(decoder.decode<Gfx::IntPoint>());
     auto resolution = TRY(decoder.decode<Gfx::IntSize>());
     auto scale_factor = TRY(decoder.decode<int>());
diff --git a/Userland/Services/WindowServer/WMConnectionFromClient.cpp b/Userland/Services/WindowServer/WMConnectionFromClient.cpp
index 288ae9af478..22773749cd8 100644
--- a/Userland/Services/WindowServer/WMConnectionFromClient.cpp
+++ b/Userland/Services/WindowServer/WMConnectionFromClient.cpp
@@ -182,7 +182,7 @@ void WMConnectionFromClient::set_window_taskbar_rect(i32 client_id, i32 window_i
     window.set_taskbar_rect(rect);
 }
 
-void WMConnectionFromClient::set_keymap(DeprecatedString const& keymap)
+void WMConnectionFromClient::set_keymap(ByteString const& keymap)
 {
     WindowManager::the().keymap_switcher()->set_keymap(keymap);
 }
diff --git a/Userland/Services/WindowServer/WMConnectionFromClient.h b/Userland/Services/WindowServer/WMConnectionFromClient.h
index 348a5cdbfd8..f2beb3a396e 100644
--- a/Userland/Services/WindowServer/WMConnectionFromClient.h
+++ b/Userland/Services/WindowServer/WMConnectionFromClient.h
@@ -31,7 +31,7 @@ public:
     virtual void set_event_mask(u32) override;
     virtual void set_manager_window(i32) override;
     virtual void set_workspace(u32, u32) override;
-    virtual void set_keymap(DeprecatedString const&) override;
+    virtual void set_keymap(ByteString const&) override;
 
     unsigned event_mask() const { return m_event_mask; }
     int window_id() const { return m_window_id; }
diff --git a/Userland/Services/WindowServer/Window.cpp b/Userland/Services/WindowServer/Window.cpp
index 0e791b2ee29..466a1741b80 100644
--- a/Userland/Services/WindowServer/Window.cpp
+++ b/Userland/Services/WindowServer/Window.cpp
@@ -24,7 +24,7 @@
 
 namespace WindowServer {
 
-static DeprecatedString default_window_icon_path()
+static ByteString default_window_icon_path()
 {
     return "/res/icons/16x16/window.png";
 }
@@ -136,7 +136,7 @@ void Window::destroy()
     set_visible(false);
 }
 
-void Window::set_title(DeprecatedString const& title)
+void Window::set_title(ByteString const& title)
 {
     if (m_title == title)
         return;
@@ -1136,17 +1136,17 @@ void Window::set_modified(bool modified)
     frame().invalidate_titlebar();
 }
 
-DeprecatedString Window::computed_title() const
+ByteString Window::computed_title() const
 {
-    DeprecatedString title = m_title.replace("[*]"sv, is_modified() ? " (*)"sv : ""sv, ReplaceMode::FirstOnly);
+    ByteString title = m_title.replace("[*]"sv, is_modified() ? " (*)"sv : ""sv, ReplaceMode::FirstOnly);
     if (m_title_username.has_value())
-        title = DeprecatedString::formatted("{} [{}]", title, m_title_username.value());
+        title = ByteString::formatted("{} [{}]", title, m_title_username.value());
     if (client() && client()->is_unresponsive())
-        return DeprecatedString::formatted("{} (Not responding)", title);
+        return ByteString::formatted("{} (Not responding)", title);
     return title;
 }
 
-ErrorOr<Optional<DeprecatedString>> Window::compute_title_username(ConnectionFromClient* client)
+ErrorOr<Optional<ByteString>> Window::compute_title_username(ConnectionFromClient* client)
 {
     if (!client)
         return Error::from_string_literal("Tried to compute title username without a client");
@@ -1160,7 +1160,7 @@ ErrorOr<Optional<DeprecatedString>> Window::compute_title_username(ConnectionFro
     if (!login_session_stat.has_value())
         return Error::from_string_literal("Failed to find login process stat");
     if (login_session_stat.value().uid == client_stat.value().uid)
-        return Optional<DeprecatedString> {};
+        return Optional<ByteString> {};
     return client_stat.value().username;
 }
 
diff --git a/Userland/Services/WindowServer/Window.h b/Userland/Services/WindowServer/Window.h
index 23b361803b4..d939a1d264a 100644
--- a/Userland/Services/WindowServer/Window.h
+++ b/Userland/Services/WindowServer/Window.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include "HitTestResult.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/IntrusiveList.h>
 #include <AK/WeakPtr.h>
 #include <LibCore/EventReceiver.h>
@@ -152,10 +152,10 @@ public:
     bool is_internal() const { return m_client_id == -1; }
     i32 client_id() const { return m_client_id; }
 
-    DeprecatedString title() const { return m_title; }
-    void set_title(DeprecatedString const&);
+    ByteString title() const { return m_title; }
+    void set_title(ByteString const&);
 
-    DeprecatedString computed_title() const;
+    ByteString computed_title() const;
 
     void set_hit_testing_enabled(bool value)
     {
@@ -387,7 +387,7 @@ private:
     void ensure_window_menu();
     void update_window_menu_items();
     void tile_type_changed(Optional<Screen const&> = {});
-    ErrorOr<Optional<DeprecatedString>> compute_title_username(ConnectionFromClient* client);
+    ErrorOr<Optional<ByteString>> compute_title_username(ConnectionFromClient* client);
 
     void exit_roll_up_mode();
 
@@ -398,8 +398,8 @@ private:
 
     Menubar m_menubar;
 
-    DeprecatedString m_title;
-    Optional<DeprecatedString> m_title_username;
+    ByteString m_title;
+    Optional<ByteString> m_title_username;
     Gfx::IntRect m_rect;
     Gfx::IntRect m_saved_before_roll_up_rect;
     Gfx::IntRect m_saved_nonfullscreen_rect;
diff --git a/Userland/Services/WindowServer/WindowClient.ipc b/Userland/Services/WindowServer/WindowClient.ipc
index aca0b8a7d75..5da1570e42b 100644
--- a/Userland/Services/WindowServer/WindowClient.ipc
+++ b/Userland/Services/WindowServer/WindowClient.ipc
@@ -3,7 +3,7 @@
 
 endpoint WindowClient
 {
-    fast_greet(Vector<Gfx::IntRect> screen_rects, u32 main_screen_index, u32 workspace_rows, u32 workspace_columns, Core::AnonymousBuffer theme_buffer, DeprecatedString default_font_query, DeprecatedString fixed_width_font_query, DeprecatedString window_title_font_query, Vector<bool> effects, i32 client_id) =|
+    fast_greet(Vector<Gfx::IntRect> screen_rects, u32 main_screen_index, u32 workspace_rows, u32 workspace_columns, Core::AnonymousBuffer theme_buffer, ByteString default_font_query, ByteString fixed_width_font_query, ByteString window_title_font_query, Vector<bool> effects, i32 client_id) =|
 
     paint(i32 window_id, Gfx::IntSize window_size, Vector<Gfx::IntRect> rects) =|
     mouse_move(i32 window_id, Gfx::IntPoint mouse_position, u32 button, u32 buttons, u32 modifiers, i32 wheel_delta_x, i32 wheel_delta_y, i32 wheel_raw_delta_x, i32 wheel_raw_delta_y, bool is_drag, Vector<String> mime_types) =|
@@ -36,10 +36,10 @@ endpoint WindowClient
     drag_accepted() =|
     drag_cancelled() =|
 
-    drag_dropped(i32 window_id, Gfx::IntPoint mouse_position, [UTF8] DeprecatedString text, HashMap<String,ByteBuffer> mime_data) =|
+    drag_dropped(i32 window_id, Gfx::IntPoint mouse_position, [UTF8] ByteString text, HashMap<String,ByteBuffer> mime_data) =|
 
     update_system_theme(Core::AnonymousBuffer theme_buffer) =|
-    update_system_fonts(DeprecatedString default_font_query, DeprecatedString fixed_width_font_query, DeprecatedString window_title_font_query) =|
+    update_system_fonts(ByteString default_font_query, ByteString fixed_width_font_query, ByteString window_title_font_query) =|
     update_system_effects(Vector<bool> effects) =|
 
     display_link_notification() =|
diff --git a/Userland/Services/WindowServer/WindowFrame.cpp b/Userland/Services/WindowServer/WindowFrame.cpp
index 0c43511bf09..71ad99ae68a 100644
--- a/Userland/Services/WindowServer/WindowFrame.cpp
+++ b/Userland/Services/WindowServer/WindowFrame.cpp
@@ -54,11 +54,11 @@ static RefPtr<MultiScaleBitmaps> s_inactive_window_shadow;
 static RefPtr<MultiScaleBitmaps> s_menu_shadow;
 static RefPtr<MultiScaleBitmaps> s_taskbar_shadow;
 static RefPtr<MultiScaleBitmaps> s_tooltip_shadow;
-static DeprecatedString s_last_active_window_shadow_path;
-static DeprecatedString s_last_inactive_window_shadow_path;
-static DeprecatedString s_last_menu_shadow_path;
-static DeprecatedString s_last_taskbar_shadow_path;
-static DeprecatedString s_last_tooltip_shadow_path;
+static ByteString s_last_active_window_shadow_path;
+static ByteString s_last_inactive_window_shadow_path;
+static ByteString s_last_menu_shadow_path;
+static ByteString s_last_taskbar_shadow_path;
+static ByteString s_last_tooltip_shadow_path;
 
 Gfx::IntRect WindowFrame::frame_rect_for_window(Window& window, Gfx::IntRect const& rect)
 {
@@ -148,7 +148,7 @@ void WindowFrame::set_button_icons()
 
 void WindowFrame::reload_config()
 {
-    DeprecatedString icons_path = WindowManager::the().palette().title_button_icons_path();
+    ByteString icons_path = WindowManager::the().palette().title_button_icons_path();
 
     auto reload_bitmap = [&](RefPtr<MultiScaleBitmaps>& multiscale_bitmap, StringView path, StringView default_path = ""sv) {
         StringBuilder full_path;
@@ -177,9 +177,9 @@ void WindowFrame::reload_config()
     reload_icon(s_close_icon, "window-close"sv, "/res/icons/16x16/window-close.png"sv);
     reload_icon(s_close_modified_icon, "window-close-modified"sv, "/res/icons/16x16/window-close-modified.png"sv);
 
-    auto load_shadow = [](DeprecatedString const& path, DeprecatedString& last_path, RefPtr<MultiScaleBitmaps>& shadow_bitmap) {
+    auto load_shadow = [](ByteString const& path, ByteString& last_path, RefPtr<MultiScaleBitmaps>& shadow_bitmap) {
         if (path.is_empty()) {
-            last_path = DeprecatedString::empty();
+            last_path = ByteString::empty();
             shadow_bitmap = nullptr;
         } else if (!shadow_bitmap || last_path != path) {
             if (shadow_bitmap)
@@ -189,7 +189,7 @@ void WindowFrame::reload_config()
             if (shadow_bitmap)
                 last_path = path;
             else
-                last_path = DeprecatedString::empty();
+                last_path = ByteString::empty();
         }
     };
     load_shadow(WindowManager::the().palette().active_window_shadow_path(), s_last_active_window_shadow_path, s_active_window_shadow);
diff --git a/Userland/Services/WindowServer/WindowFrame.h b/Userland/Services/WindowServer/WindowFrame.h
index f71800a0291..f15c77221d1 100644
--- a/Userland/Services/WindowServer/WindowFrame.h
+++ b/Userland/Services/WindowServer/WindowFrame.h
@@ -126,7 +126,7 @@ private:
     void handle_menu_mouse_event(Menu&, MouseEvent const&);
 
     Gfx::WindowTheme::WindowState window_state_for_theme() const;
-    DeprecatedString computed_title() const;
+    ByteString computed_title() const;
 
     Gfx::IntRect constrained_render_rect_to_screen(Gfx::IntRect const&) const;
     Gfx::IntRect leftmost_titlebar_button_rect() const;
diff --git a/Userland/Services/WindowServer/WindowManager.cpp b/Userland/Services/WindowServer/WindowManager.cpp
index 06e96590587..de58a10513b 100644
--- a/Userland/Services/WindowServer/WindowManager.cpp
+++ b/Userland/Services/WindowServer/WindowManager.cpp
@@ -55,7 +55,7 @@ WindowManager::WindowManager(Gfx::PaletteImpl& palette)
 
     reload_config();
 
-    m_keymap_switcher->on_keymap_change = [&](DeprecatedString const& keymap) {
+    m_keymap_switcher->on_keymap_change = [&](ByteString const& keymap) {
         for_each_window_manager([&keymap](WMConnectionFromClient& conn) {
             if (!(conn.event_mask() & WMEventMask::KeymapChanged))
                 return IterationDecision::Continue;
@@ -89,7 +89,7 @@ void WindowManager::reload_config()
     m_cursor_highlight_color = Color::from_string(g_config->read_entry("Mouse", "CursorHighlightColor")).value_or(default_highlight_color);
     apply_cursor_theme(g_config->read_entry("Mouse", "CursorTheme", "Default"));
 
-    auto reload_graphic = [&](RefPtr<MultiScaleBitmaps>& bitmap, DeprecatedString const& name) {
+    auto reload_graphic = [&](RefPtr<MultiScaleBitmaps>& bitmap, ByteString const& name) {
         if (bitmap) {
             if (!bitmap->load(name))
                 bitmap = nullptr;
@@ -116,7 +116,7 @@ Gfx::Font const& WindowManager::window_title_font() const
     return Gfx::FontDatabase::window_title_font();
 }
 
-bool WindowManager::set_screen_layout(ScreenLayout&& screen_layout, bool save, DeprecatedString& error_msg)
+bool WindowManager::set_screen_layout(ScreenLayout&& screen_layout, bool save, ByteString& error_msg)
 {
     if (!Screen::apply_layout(move(screen_layout), error_msg))
         return false;
@@ -146,7 +146,7 @@ ScreenLayout WindowManager::get_screen_layout() const
     return Screen::layout();
 }
 
-bool WindowManager::save_screen_layout(DeprecatedString& error_msg)
+bool WindowManager::save_screen_layout(ByteString& error_msg)
 {
     if (!Screen::layout().save_config(*g_config)) {
         error_msg = "Could not save";
@@ -266,7 +266,7 @@ void WindowManager::set_acceleration_factor(double factor)
 {
     ScreenInput::the().set_acceleration_factor(factor);
     dbgln("Saving acceleration factor {} to config file at {}", factor, g_config->filename());
-    g_config->write_entry("Mouse", "AccelerationFactor", DeprecatedString::formatted("{}", factor));
+    g_config->write_entry("Mouse", "AccelerationFactor", ByteString::formatted("{}", factor));
     sync_config_to_disk();
 }
 
@@ -274,7 +274,7 @@ void WindowManager::set_scroll_step_size(unsigned step_size)
 {
     ScreenInput::the().set_scroll_step_size(step_size);
     dbgln("Saving scroll step size {} to config file at {}", step_size, g_config->filename());
-    g_config->write_entry("Mouse", "ScrollStepSize", DeprecatedString::number(step_size));
+    g_config->write_entry("Mouse", "ScrollStepSize", ByteString::number(step_size));
     sync_config_to_disk();
 }
 
@@ -283,7 +283,7 @@ void WindowManager::set_double_click_speed(int speed)
     VERIFY(speed >= double_click_speed_min && speed <= double_click_speed_max);
     m_double_click_speed = speed;
     dbgln("Saving double-click speed {} to config file at {}", speed, g_config->filename());
-    g_config->write_entry("Input", "DoubleClickSpeed", DeprecatedString::number(speed));
+    g_config->write_entry("Input", "DoubleClickSpeed", ByteString::number(speed));
     sync_config_to_disk();
 }
 
@@ -2117,7 +2117,7 @@ Gfx::IntRect WindowManager::tiled_window_rect(Window const& window, Optional<Scr
     return rect;
 }
 
-void WindowManager::start_dnd_drag(ConnectionFromClient& client, DeprecatedString const& text, Gfx::Bitmap const* bitmap, Core::MimeData const& mime_data)
+void WindowManager::start_dnd_drag(ConnectionFromClient& client, ByteString const& text, Gfx::Bitmap const* bitmap, Core::MimeData const& mime_data)
 {
     VERIFY(!m_dnd_client);
     m_dnd_client = client;
@@ -2148,7 +2148,7 @@ void WindowManager::set_accepts_drag(bool accepts)
 
 void WindowManager::invalidate_after_theme_or_font_change()
 {
-    Compositor::the().set_background_color(g_config->read_entry("Background", "Color", palette().desktop_background().to_deprecated_string()));
+    Compositor::the().set_background_color(g_config->read_entry("Background", "Color", palette().desktop_background().to_byte_string()));
     WindowFrame::reload_config();
     for_each_window_stack([&](auto& window_stack) {
         window_stack.for_each_window([&](Window& window) {
@@ -2166,7 +2166,7 @@ void WindowManager::invalidate_after_theme_or_font_change()
     Compositor::the().invalidate_after_theme_or_font_change();
 }
 
-bool WindowManager::update_theme(DeprecatedString theme_path, DeprecatedString theme_name, bool keep_desktop_background, Optional<DeprecatedString> const& color_scheme_path)
+bool WindowManager::update_theme(ByteString theme_path, ByteString theme_name, bool keep_desktop_background, Optional<ByteString> const& color_scheme_path)
 {
     auto error_or_new_theme = Gfx::load_system_theme(theme_path, color_scheme_path);
     if (error_or_new_theme.is_error()) {
@@ -2217,7 +2217,7 @@ void WindowManager::clear_theme_override()
 {
     m_theme_overridden = false;
     auto previous_theme_name = g_config->read_entry("Theme", "Name");
-    auto previous_theme = MUST(Gfx::load_system_theme(DeprecatedString::formatted("/res/themes/{}.ini", previous_theme_name), m_preferred_color_scheme));
+    auto previous_theme = MUST(Gfx::load_system_theme(ByteString::formatted("/res/themes/{}.ini", previous_theme_name), m_preferred_color_scheme));
     Gfx::set_system_theme(previous_theme);
     m_palette = Gfx::PaletteImpl::create_with_anonymous_buffer(previous_theme);
     invalidate_after_theme_or_font_change();
@@ -2329,9 +2329,9 @@ WindowStack& WindowManager::get_rendering_window_stacks(WindowStack*& transition
     return Compositor::the().get_rendering_window_stacks(transitioning_window_stack);
 }
 
-void WindowManager::apply_cursor_theme(DeprecatedString const& theme_name)
+void WindowManager::apply_cursor_theme(ByteString const& theme_name)
 {
-    auto theme_path = DeprecatedString::formatted("/res/cursor-themes/{}/{}", theme_name, "Config.ini");
+    auto theme_path = ByteString::formatted("/res/cursor-themes/{}/{}", theme_name, "Config.ini");
     auto cursor_theme_config_or_error = Core::ConfigFile::open(theme_path);
     if (cursor_theme_config_or_error.is_error()) {
         dbgln("Unable to open cursor theme '{}': {}", theme_path, cursor_theme_config_or_error.error());
@@ -2340,11 +2340,11 @@ void WindowManager::apply_cursor_theme(DeprecatedString const& theme_name)
     auto cursor_theme_config = cursor_theme_config_or_error.release_value();
 
     auto* current_cursor = Compositor::the().current_cursor();
-    auto reload_cursor = [&](RefPtr<Cursor const>& cursor, DeprecatedString const& name) {
+    auto reload_cursor = [&](RefPtr<Cursor const>& cursor, ByteString const& name) {
         bool is_current_cursor = current_cursor && current_cursor == cursor.ptr();
 
         static auto const s_default_cursor_path = "/res/cursor-themes/Default/arrow.x2y2.png"sv;
-        cursor = Cursor::create(DeprecatedString::formatted("/res/cursor-themes/{}/{}", theme_name, cursor_theme_config->read_entry("Cursor", name)), s_default_cursor_path);
+        cursor = Cursor::create(ByteString::formatted("/res/cursor-themes/{}/{}", theme_name, cursor_theme_config->read_entry("Cursor", name)), s_default_cursor_path);
 
         if (is_current_cursor) {
             Compositor::the().current_cursor_was_reloaded(cursor.ptr());
@@ -2397,7 +2397,7 @@ void WindowManager::set_cursor_highlight_color(Gfx::Color color)
 {
     m_cursor_highlight_color = color;
     Compositor::the().invalidate_cursor();
-    g_config->write_entry("Mouse", "CursorHighlightColor", color.to_deprecated_string());
+    g_config->write_entry("Mouse", "CursorHighlightColor", color.to_byte_string());
     sync_config_to_disk();
 }
 
diff --git a/Userland/Services/WindowServer/WindowManager.h b/Userland/Services/WindowServer/WindowManager.h
index 56acd5bb40c..9cdc9f65655 100644
--- a/Userland/Services/WindowServer/WindowManager.h
+++ b/Userland/Services/WindowServer/WindowManager.h
@@ -85,7 +85,7 @@ public:
     ConnectionFromClient const* dnd_client() const { return m_dnd_client.ptr(); }
     Core::MimeData const& dnd_mime_data() const { return *m_dnd_mime_data; }
 
-    void start_dnd_drag(ConnectionFromClient&, DeprecatedString const& text, Gfx::Bitmap const*, Core::MimeData const&);
+    void start_dnd_drag(ConnectionFromClient&, ByteString const& text, Gfx::Bitmap const*, Core::MimeData const&);
     void end_dnd_drag();
 
     void set_accepts_drag(bool);
@@ -146,9 +146,9 @@ public:
     Gfx::Font const& font() const;
     Gfx::Font const& window_title_font() const;
 
-    bool set_screen_layout(ScreenLayout&&, bool, DeprecatedString&);
+    bool set_screen_layout(ScreenLayout&&, bool, ByteString&);
     ScreenLayout get_screen_layout() const;
-    bool save_screen_layout(DeprecatedString&);
+    bool save_screen_layout(ByteString&);
 
     void set_acceleration_factor(double);
     void set_scroll_step_size(unsigned);
@@ -202,14 +202,14 @@ public:
         return nullptr;
     }
 
-    bool update_theme(DeprecatedString theme_path, DeprecatedString theme_name, bool keep_desktop_background, Optional<DeprecatedString> const& color_scheme_path);
+    bool update_theme(ByteString theme_path, ByteString theme_name, bool keep_desktop_background, Optional<ByteString> const& color_scheme_path);
     void invalidate_after_theme_or_font_change();
 
     bool set_theme_override(Core::AnonymousBuffer const& theme_override);
     Optional<Core::AnonymousBuffer> get_theme_override() const;
     void clear_theme_override();
     bool is_theme_overridden() { return m_theme_overridden; }
-    Optional<DeprecatedString> get_preferred_color_scheme() { return m_preferred_color_scheme; }
+    Optional<ByteString> get_preferred_color_scheme() { return m_preferred_color_scheme; }
 
     bool set_hovered_window(Window*);
     void deliver_mouse_event(Window&, MouseEvent const&);
@@ -321,7 +321,7 @@ public:
 
     MultiScaleBitmaps const* overlay_rect_shadow() const { return m_overlay_rect_shadow.ptr(); }
 
-    void apply_cursor_theme(DeprecatedString const& name);
+    void apply_cursor_theme(ByteString const& name);
 
     void set_cursor_highlight_radius(int radius);
     void set_cursor_highlight_color(Gfx::Color color);
@@ -449,7 +449,7 @@ private:
     bool m_mouse_buttons_switched { false };
     bool m_natural_scroll { false };
     bool m_theme_overridden { false };
-    Optional<DeprecatedString> m_preferred_color_scheme { OptionalNone() };
+    Optional<ByteString> m_preferred_color_scheme { OptionalNone() };
 
     WeakPtr<Window> m_hovered_window;
     WeakPtr<Window> m_highlight_window;
@@ -488,7 +488,7 @@ private:
 
     OwnPtr<DndOverlay> m_dnd_overlay;
     WeakPtr<ConnectionFromClient> m_dnd_client;
-    DeprecatedString m_dnd_text;
+    ByteString m_dnd_text;
     bool m_dnd_accepts_drag { false };
 
     RefPtr<Core::MimeData const> m_dnd_mime_data;
diff --git a/Userland/Services/WindowServer/WindowManagerClient.ipc b/Userland/Services/WindowServer/WindowManagerClient.ipc
index 4d0d4588b47..cd092d56e5f 100644
--- a/Userland/Services/WindowServer/WindowManagerClient.ipc
+++ b/Userland/Services/WindowServer/WindowManagerClient.ipc
@@ -3,7 +3,7 @@
 endpoint WindowManagerClient
 {
     window_removed(i32 wm_id, i32 client_id, i32 window_id) =|
-    window_state_changed(i32 wm_id, i32 client_id, i32 window_id, u32 workspace_row, u32 workspace_column, bool is_active, bool is_blocking, bool is_minimized, bool is_frameless, i32 window_type, [UTF8] DeprecatedString title, Gfx::IntRect rect, Optional<i32> progress) =|
+    window_state_changed(i32 wm_id, i32 client_id, i32 window_id, u32 workspace_row, u32 workspace_column, bool is_active, bool is_blocking, bool is_minimized, bool is_frameless, i32 window_type, [UTF8] ByteString title, Gfx::IntRect rect, Optional<i32> progress) =|
     window_icon_bitmap_changed(i32 wm_id, i32 client_id, i32 window_id, Gfx::ShareableBitmap bitmap) =|
     window_rect_changed(i32 wm_id, i32 client_id, i32 window_id, Gfx::IntRect rect) =|
     applet_area_size_changed(i32 wm_id, Gfx::IntSize size) =|
@@ -12,6 +12,6 @@ endpoint WindowManagerClient
     super_d_key_pressed(i32 wm_id) =|
     super_digit_key_pressed(i32 wm_id, u8 digit) =|
     workspace_changed(i32 wm_id, u32 row, u32 column) =|
-    keymap_changed(i32 wm_id, [UTF8] DeprecatedString keymap) =|
+    keymap_changed(i32 wm_id, [UTF8] ByteString keymap) =|
     add_to_quick_launch(i32 wm_id, i32 process_id) =|
 }
diff --git a/Userland/Services/WindowServer/WindowManagerServer.ipc b/Userland/Services/WindowServer/WindowManagerServer.ipc
index 0abb7eddebb..8bbc3104c6d 100644
--- a/Userland/Services/WindowServer/WindowManagerServer.ipc
+++ b/Userland/Services/WindowServer/WindowManagerServer.ipc
@@ -13,5 +13,5 @@ endpoint WindowManagerServer
     set_window_taskbar_rect(i32 client_id, i32 window_id, Gfx::IntRect rect) =|
     set_applet_area_position(Gfx::IntPoint position) =|
     set_workspace(u32 row, u32 column) =|
-    set_keymap([UTF8] DeprecatedString keymap) =|
+    set_keymap([UTF8] ByteString keymap) =|
 }
diff --git a/Userland/Services/WindowServer/WindowServer.ipc b/Userland/Services/WindowServer/WindowServer.ipc
index 5d1871e11bf..12a26d56c77 100644
--- a/Userland/Services/WindowServer/WindowServer.ipc
+++ b/Userland/Services/WindowServer/WindowServer.ipc
@@ -14,13 +14,13 @@ endpoint WindowServer
         i32 menu_id,
         i32 identifier,
         i32 submenu_id,
-        [UTF8] DeprecatedString text,
+        [UTF8] ByteString text,
         bool enabled,
         bool visible,
         bool checkable,
         bool checked,
         bool is_default,
-        [UTF8] DeprecatedString shortcut,
+        [UTF8] ByteString shortcut,
         Gfx::ShareableBitmap icon,
         bool exclusive) =|
 
@@ -30,13 +30,13 @@ endpoint WindowServer
         i32 menu_id,
         i32 identifier,
         i32 submenu_id,
-        [UTF8] DeprecatedString text,
+        [UTF8] ByteString text,
         bool enabled,
         bool visible,
         bool checkable,
         bool checked,
         bool is_default,
-        [UTF8] DeprecatedString shortcut,
+        [UTF8] ByteString shortcut,
         Gfx::ShareableBitmap icon) =|
 
     remove_menu_item(i32 menu_id, i32 identifier) =|
@@ -61,14 +61,14 @@ endpoint WindowServer
         Optional<Gfx::IntSize> resize_aspect_ratio,
         i32 type,
         i32 mode,
-        [UTF8] DeprecatedString title,
+        [UTF8] ByteString title,
         i32 parent_window_id,
         Gfx::IntRect launch_origin_rect) =|
 
     destroy_window(i32 window_id) => (Vector<i32> destroyed_window_ids)
 
-    set_window_title(i32 window_id, [UTF8] DeprecatedString title) =|
-    get_window_title(i32 window_id) => ([UTF8] DeprecatedString title)
+    set_window_title(i32 window_id, [UTF8] ByteString title) =|
+    get_window_title(i32 window_id) => ([UTF8] ByteString title)
 
     set_window_progress(i32 window_id, Optional<i32> progress) =|
 
@@ -112,12 +112,12 @@ endpoint WindowServer
 
     set_wallpaper(Gfx::ShareableBitmap wallpaper_bitmap) => (bool success)
 
-    set_background_color(DeprecatedString background_color) =|
-    set_wallpaper_mode(DeprecatedString mode) =|
+    set_background_color(ByteString background_color) =|
+    set_wallpaper_mode(ByteString mode) =|
 
-    set_screen_layout(::WindowServer::ScreenLayout screen_layout, bool save) => (bool success, DeprecatedString error_msg)
+    set_screen_layout(::WindowServer::ScreenLayout screen_layout, bool save) => (bool success, ByteString error_msg)
     get_screen_layout() => (::WindowServer::ScreenLayout screen_layout)
-    save_screen_layout() => (bool success, DeprecatedString error_msg)
+    save_screen_layout() => (bool success, ByteString error_msg)
     show_screen_numbers(bool show) =|
 
     apply_workspace_settings(u32 rows, u32 columns, bool save) => (bool success)
@@ -129,11 +129,11 @@ endpoint WindowServer
     set_window_cursor(i32 window_id, i32 cursor_type) =|
     set_window_custom_cursor(i32 window_id, Gfx::ShareableBitmap cursor) =|
 
-    start_drag([UTF8] DeprecatedString text, HashMap<String,ByteBuffer> mime_data, Gfx::ShareableBitmap drag_bitmap) => (bool started)
+    start_drag([UTF8] ByteString text, HashMap<String,ByteBuffer> mime_data, Gfx::ShareableBitmap drag_bitmap) => (bool started)
     set_accepts_drag(bool accepts) =|
 
-    set_system_theme(DeprecatedString theme_path, [UTF8] DeprecatedString theme_name, bool keep_desktop_background, Optional<DeprecatedString> color_scheme_path) => (bool success)
-    get_system_theme() => ([UTF8] DeprecatedString theme_name)
+    set_system_theme(ByteString theme_path, [UTF8] ByteString theme_name, bool keep_desktop_background, Optional<ByteString> color_scheme_path) => (bool success)
+    get_system_theme() => ([UTF8] ByteString theme_name)
     refresh_system_theme() =|
 
     set_system_theme_override(Core::AnonymousBuffer buffer) => (bool success)
@@ -141,10 +141,10 @@ endpoint WindowServer
     clear_system_theme_override() =|
     is_system_theme_overridden() => (bool overridden)
 
-    get_preferred_color_scheme() => (Optional<DeprecatedString> path)
+    get_preferred_color_scheme() => (Optional<ByteString> path)
 
-    apply_cursor_theme(DeprecatedString name) =|
-    get_cursor_theme() => (DeprecatedString name)
+    apply_cursor_theme(ByteString name) =|
+    get_cursor_theme() => (ByteString name)
 
     set_cursor_highlight_radius(int radius) =|
     get_cursor_highlight_radius() => (int radius)
@@ -152,7 +152,7 @@ endpoint WindowServer
     set_cursor_highlight_color(Gfx::Color color) =|
     get_cursor_highlight_color() => (Gfx::Color color)
 
-    set_system_fonts(DeprecatedString default_font_query, DeprecatedString fixed_width_font_query, DeprecatedString window_title_font_query) => (bool success)
+    set_system_fonts(ByteString default_font_query, ByteString fixed_width_font_query, ByteString window_title_font_query) => (bool success)
     set_system_effects(Vector<bool> effects, u8 geometry, u8 tile_window) =|
 
     set_window_base_size_and_size_increment(i32 window_id, Gfx::IntSize base_size, Gfx::IntSize size_increment) =|
diff --git a/Userland/Services/WindowServer/WindowSwitcher.cpp b/Userland/Services/WindowServer/WindowSwitcher.cpp
index df182ac589e..fa05cfc5948 100644
--- a/Userland/Services/WindowServer/WindowSwitcher.cpp
+++ b/Userland/Services/WindowServer/WindowSwitcher.cpp
@@ -203,7 +203,7 @@ void WindowSwitcher::draw()
         painter.blit(icon_rect.location(), window.icon(), window.icon().rect());
         painter.draw_text(item_rect.translated(thumbnail_width() + 12, 0).translated(1), window.computed_title(), WindowManager::the().window_title_font(), Gfx::TextAlignment::CenterLeft, text_color.inverted());
         painter.draw_text(item_rect.translated(thumbnail_width() + 12, 0), window.computed_title(), WindowManager::the().window_title_font(), Gfx::TextAlignment::CenterLeft, text_color);
-        auto window_details = m_windows_on_multiple_stacks ? DeprecatedString::formatted("{} on {}:{}", window.rect().to_deprecated_string(), window.window_stack().row() + 1, window.window_stack().column() + 1) : window.rect().to_deprecated_string();
+        auto window_details = m_windows_on_multiple_stacks ? ByteString::formatted("{} on {}:{}", window.rect().to_byte_string(), window.window_stack().row() + 1, window.window_stack().column() + 1) : window.rect().to_byte_string();
         painter.draw_text(item_rect, window_details, Gfx::TextAlignment::CenterRight, rect_text_color);
     }
 }
diff --git a/Userland/Services/WindowServer/main.cpp b/Userland/Services/WindowServer/main.cpp
index 9c95ea624e4..d41dd93843f 100644
--- a/Userland/Services/WindowServer/main.cpp
+++ b/Userland/Services/WindowServer/main.cpp
@@ -47,11 +47,11 @@ ErrorOr<int> serenity_main(Main::Arguments)
     WindowServer::g_config = TRY(Core::ConfigFile::open("/etc/WindowServer.ini", Core::ConfigFile::AllowWriting::Yes));
     auto theme_name = WindowServer::g_config->read_entry("Theme", "Name", "Default");
 
-    Optional<DeprecatedString> custom_color_scheme_path = OptionalNone();
+    Optional<ByteString> custom_color_scheme_path = OptionalNone();
     if (WindowServer::g_config->read_bool_entry("Theme", "LoadCustomColorScheme", false))
         custom_color_scheme_path = WindowServer::g_config->read_entry("Theme", "CustomColorSchemePath");
 
-    auto theme = TRY(Gfx::load_system_theme(DeprecatedString::formatted("/res/themes/{}.ini", theme_name), custom_color_scheme_path));
+    auto theme = TRY(Gfx::load_system_theme(ByteString::formatted("/res/themes/{}.ini", theme_name), custom_color_scheme_path));
     Gfx::set_system_theme(theme);
     auto palette = Gfx::PaletteImpl::create_with_anonymous_buffer(theme);
 
@@ -77,9 +77,9 @@ ErrorOr<int> serenity_main(Main::Arguments)
 
     // First check which screens are explicitly configured
     {
-        AK::HashTable<DeprecatedString> fb_devices_configured;
+        AK::HashTable<ByteString> fb_devices_configured;
         WindowServer::ScreenLayout screen_layout;
-        DeprecatedString error_msg;
+        ByteString error_msg;
 
         auto add_unconfigured_display_connector_devices = [&]() -> ErrorOr<void> {
             // Enumerate the /dev/gpu/connectorX devices and try to set up any ones we find that we haven't already used
@@ -88,7 +88,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
                 auto path = di.next_path();
                 if (!path.starts_with("connector"sv))
                     continue;
-                auto full_path = DeprecatedString::formatted("/dev/gpu/{}", path);
+                auto full_path = ByteString::formatted("/dev/gpu/{}", path);
                 if (!FileSystem::is_device(full_path))
                     continue;
                 auto display_connector_fd = TRY(Core::System::open(full_path, O_RDWR | O_CLOEXEC));
diff --git a/Userland/Shell/AST.cpp b/Userland/Shell/AST.cpp
index d8845288f7e..7c01228f627 100644
--- a/Userland/Shell/AST.cpp
+++ b/Userland/Shell/AST.cpp
@@ -109,7 +109,7 @@ namespace Shell::AST {
 template<typename... Args>
 static inline void print_indented(int indent, CheckedFormatString<Args...> format, Args&&... args)
 {
-    auto str = DeprecatedString::formatted(format.view(), forward<Args>(args)...);
+    auto str = ByteString::formatted(format.view(), forward<Args>(args)...);
     dbgln("{: >{}}", str, str.length() + indent * 2);
 }
 
@@ -179,7 +179,7 @@ static ErrorOr<String> resolve_slices(RefPtr<Shell> shell, String&& input_value,
         for (auto& value : index_values) {
             auto maybe_index = value.bytes_as_string_view().to_int();
             if (!maybe_index.has_value()) {
-                shell->raise_error(Shell::ShellError::InvalidSliceContentsError, DeprecatedString::formatted("Invalid value in slice index {}: {} (expected a number)", i, value), slice->position());
+                shell->raise_error(Shell::ShellError::InvalidSliceContentsError, ByteString::formatted("Invalid value in slice index {}: {} (expected a number)", i, value), slice->position());
                 return move(input_value);
             }
             ++i;
@@ -190,7 +190,7 @@ static ErrorOr<String> resolve_slices(RefPtr<Shell> shell, String&& input_value,
                 index += input_value.bytes_as_string_view().length();
 
             if (index < 0 || (size_t)index >= input_value.bytes_as_string_view().length()) {
-                shell->raise_error(Shell::ShellError::InvalidSliceContentsError, DeprecatedString::formatted("Slice index {} (evaluated as {}) out of value bounds [0-{})", index, original_index, input_value.bytes_as_string_view().length()), slice->position());
+                shell->raise_error(Shell::ShellError::InvalidSliceContentsError, ByteString::formatted("Slice index {} (evaluated as {}) out of value bounds [0-{})", index, original_index, input_value.bytes_as_string_view().length()), slice->position());
                 return move(input_value);
             }
             indices.unchecked_append(index);
@@ -229,7 +229,7 @@ static ErrorOr<Vector<String>> resolve_slices(RefPtr<Shell> shell, Vector<String
         for (auto& value : index_values) {
             auto maybe_index = value.bytes_as_string_view().to_int();
             if (!maybe_index.has_value()) {
-                shell->raise_error(Shell::ShellError::InvalidSliceContentsError, DeprecatedString::formatted("Invalid value in slice index {}: {} (expected a number)", i, value), slice->position());
+                shell->raise_error(Shell::ShellError::InvalidSliceContentsError, ByteString::formatted("Invalid value in slice index {}: {} (expected a number)", i, value), slice->position());
                 return move(values);
             }
             ++i;
@@ -240,7 +240,7 @@ static ErrorOr<Vector<String>> resolve_slices(RefPtr<Shell> shell, Vector<String
                 index += values.size();
 
             if (index < 0 || (size_t)index >= values.size()) {
-                shell->raise_error(Shell::ShellError::InvalidSliceContentsError, DeprecatedString::formatted("Slice index {} (evaluated as {}) out of value bounds [0-{})", index, original_index, values.size()), slice->position());
+                shell->raise_error(Shell::ShellError::InvalidSliceContentsError, ByteString::formatted("Slice index {} (evaluated as {}) out of value bounds [0-{})", index, original_index, values.size()), slice->position());
                 return move(values);
             }
             indices.unchecked_append(index);
@@ -648,7 +648,7 @@ ErrorOr<void> BarewordLiteral::highlight_in_editor(Line::Editor& editor, Shell&
                 auto name = shell.help_path_for({}, *runnable);
                 if (name.has_value()) {
                     auto url = URL::create_with_help_scheme(name.release_value(), shell.hostname);
-                    style = bold.unified_with(Line::Style::Hyperlink(url.to_deprecated_string()));
+                    style = bold.unified_with(Line::Style::Hyperlink(url.to_byte_string()));
                 }
             }
 #endif
@@ -681,8 +681,8 @@ ErrorOr<void> BarewordLiteral::highlight_in_editor(Line::Editor& editor, Shell&
     if (FileSystem::exists(m_text)) {
         auto realpath = shell.resolve_path(m_text.bytes_as_string_view());
         auto url = URL::create_with_file_scheme(realpath);
-        url.set_host(TRY(String::from_deprecated_string(shell.hostname)));
-        editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Hyperlink(url.to_deprecated_string()) });
+        url.set_host(TRY(String::from_byte_string(shell.hostname)));
+        editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Hyperlink(url.to_byte_string()) });
     }
     return {};
 }
@@ -1132,11 +1132,11 @@ ErrorOr<void> FunctionDeclaration::dump(int level) const
 
 ErrorOr<RefPtr<Value>> FunctionDeclaration::run(RefPtr<Shell> shell)
 {
-    Vector<DeprecatedString> args;
+    Vector<ByteString> args;
     for (auto& arg : m_arguments)
-        args.append(arg.name.to_deprecated_string());
+        args.append(arg.name.to_byte_string());
 
-    shell->define_function(m_name.name.to_deprecated_string(), move(args), m_block);
+    shell->define_function(m_name.name.to_byte_string(), move(args), m_block);
 
     return make_ref_counted<ListValue>({});
 }
@@ -1182,7 +1182,7 @@ ErrorOr<Vector<Line::CompletionSuggestion>> FunctionDeclaration::complete_for_ed
     Vector<Line::CompletionSuggestion> results;
     for (auto& arg : m_arguments) {
         if (arg.name.starts_with_bytes(name))
-            results.append(arg.name.to_deprecated_string());
+            results.append(arg.name.to_byte_string());
     }
 
     results.extend(TRY(matching_node->complete_for_editor(shell, offset, hit_test_result)));
@@ -1279,7 +1279,7 @@ ErrorOr<RefPtr<Value>> ForLoop::run(RefPtr<Shell> shell)
             RefPtr<Value> block_value;
 
             {
-                auto frame = shell->push_frame(DeprecatedString::formatted("for ({})", this));
+                auto frame = shell->push_frame(ByteString::formatted("for ({})", this));
                 shell->set_local_variable(variable_name.bytes_as_string_view(), value, true);
 
                 if (index_name.has_value())
@@ -1469,7 +1469,7 @@ ErrorOr<RefPtr<Value>> Heredoc::run(RefPtr<Shell> shell)
     if (rc != 0) {
         // pipe() failed for {}
         if (shell)
-            shell->raise_error(Shell::ShellError::PipeFailure, DeprecatedString::formatted("heredoc: {}", strerror(errno)), position());
+            shell->raise_error(Shell::ShellError::PipeFailure, ByteString::formatted("heredoc: {}", strerror(errno)), position());
         return nullptr;
     }
 
@@ -1605,7 +1605,7 @@ ErrorOr<RefPtr<Value>> HistoryEvent::run(RefPtr<Shell> shell)
         return it_end;
     };
     // First, resolve the event itself.
-    DeprecatedString resolved_history;
+    ByteString resolved_history;
     switch (m_selector.event.kind) {
     case HistorySelector::EventKind::IndexFromStart:
         if (m_selector.event.index >= history.size()) {
@@ -2337,9 +2337,9 @@ ErrorOr<RefPtr<Value>> MatchExpr::run(RefPtr<Shell> shell)
         }
     };
 
-    auto frame = shell->push_frame(DeprecatedString::formatted("match ({})", this));
+    auto frame = shell->push_frame(ByteString::formatted("match ({})", this));
     if (!m_expr_name.is_empty())
-        shell->set_local_variable(m_expr_name.to_deprecated_string(), value, true);
+        shell->set_local_variable(m_expr_name.to_byte_string(), value, true);
 
     for (auto& entry : m_entries) {
         auto result = TRY(entry.options.visit([&](auto& options) -> ErrorOr<Variant<IterationDecision, RefPtr<Value>>> {
@@ -2351,7 +2351,7 @@ ErrorOr<RefPtr<Value>> MatchExpr::run(RefPtr<Shell> shell)
                             size_t i = 0;
                             for (auto& name : entry.match_names.value()) {
                                 if (spans.size() > i)
-                                    shell->set_local_variable(name.to_deprecated_string(), make_ref_counted<AST::StringValue>(spans[i]), true);
+                                    shell->set_local_variable(name.to_byte_string(), make_ref_counted<AST::StringValue>(spans[i]), true);
                                 ++i;
                             }
                         }
@@ -2625,9 +2625,9 @@ ErrorOr<void> PathRedirectionNode::highlight_in_editor(Line::Editor& editor, She
         auto& path = path_text[0];
         if (!path.starts_with('/'))
             path = TRY(String::formatted("{}/{}", shell.cwd, path));
-        auto url = URL::create_with_file_scheme(path.to_deprecated_string());
-        url.set_host(TRY(String::from_deprecated_string(shell.hostname)));
-        editor.stylize({ position.start_offset, position.end_offset }, { Line::Style::Hyperlink(url.to_deprecated_string()) });
+        auto url = URL::create_with_file_scheme(path.to_byte_string());
+        url.set_host(TRY(String::from_byte_string(shell.hostname)));
+        editor.stylize({ position.start_offset, position.end_offset }, { Line::Style::Hyperlink(url.to_byte_string()) });
     }
     return {};
 }
@@ -2713,7 +2713,7 @@ ErrorOr<RefPtr<Value>> Range::run(RefPtr<Shell> shell)
                 }
             } else {
             yield_start_end:;
-                shell->raise_error(Shell::ShellError::EvaluatedSyntaxError, DeprecatedString::formatted("Cannot interpolate between '{}' and '{}'!", start_str, end_str), position);
+                shell->raise_error(Shell::ShellError::EvaluatedSyntaxError, ByteString::formatted("Cannot interpolate between '{}' and '{}'!", start_str, end_str), position);
                 // We can't really interpolate between the two, so just yield both.
                 values.append(make_ref_counted<StringValue>(move(start_str)));
                 values.append(make_ref_counted<StringValue>(move(end_str)));
@@ -3215,13 +3215,13 @@ ErrorOr<void> Juxtaposition::highlight_in_editor(Line::Editor& editor, Shell& sh
         path_builder.append(tilde_value);
         path_builder.append('/');
         path_builder.append(bareword_value);
-        auto path = path_builder.to_deprecated_string();
+        auto path = path_builder.to_byte_string();
 
         if (FileSystem::exists(path)) {
             auto realpath = shell.resolve_path(path);
             auto url = URL::create_with_file_scheme(realpath);
-            url.set_host(TRY(String::from_deprecated_string(shell.hostname)));
-            editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Hyperlink(url.to_deprecated_string()) });
+            url.set_host(TRY(String::from_byte_string(shell.hostname)));
+            editor.stylize({ m_position.start_offset, m_position.end_offset }, { Line::Style::Hyperlink(url.to_byte_string()) });
         }
 
     } else {
@@ -3398,7 +3398,7 @@ ErrorOr<void> SyntaxError::dump(int level) const
 
 ErrorOr<RefPtr<Value>> SyntaxError::run(RefPtr<Shell> shell)
 {
-    shell->raise_error(Shell::ShellError::EvaluatedSyntaxError, m_syntax_error_text.to_deprecated_string(), position());
+    shell->raise_error(Shell::ShellError::EvaluatedSyntaxError, m_syntax_error_text.to_byte_string(), position());
     return make_ref_counted<StringValue>(String {});
 }
 
@@ -3593,7 +3593,7 @@ ErrorOr<RefPtr<Value>> VariableDeclarations::run(RefPtr<Shell> shell)
             break;
         value = TRY(value->resolve_without_cast(shell));
 
-        shell->set_local_variable(name.to_deprecated_string(), value.release_nonnull());
+        shell->set_local_variable(name.to_byte_string(), value.release_nonnull());
     }
 
     return make_ref_counted<ListValue>({});
@@ -3802,7 +3802,7 @@ ErrorOr<Vector<String>> GlobValue::resolve_as_list(RefPtr<Shell> shell)
     Vector<String> strings;
     TRY(strings.try_ensure_capacity(results.size()));
     for (auto& entry : results) {
-        TRY(strings.try_append(TRY(String::from_deprecated_string(entry))));
+        TRY(strings.try_append(TRY(String::from_byte_string(entry))));
     }
 
     return resolve_slices(shell, move(strings), m_slices);
@@ -3820,7 +3820,7 @@ ErrorOr<String> SimpleVariableValue::resolve_as_string(RefPtr<Shell> shell)
     if (auto value = TRY(resolve_without_cast(shell)); value != this)
         return resolve_slices(shell, TRY(value->resolve_as_string(shell)), m_slices);
 
-    auto name = m_name.to_deprecated_string();
+    auto name = m_name.to_byte_string();
     char const* env_value = getenv(name.characters());
     if (!env_value)
         env_value = "";
@@ -3836,7 +3836,7 @@ ErrorOr<Vector<String>> SimpleVariableValue::resolve_as_list(RefPtr<Shell> shell
     if (auto value = TRY(resolve_without_cast(shell)); value != this)
         return value->resolve_as_list(shell);
 
-    auto name = m_name.to_deprecated_string();
+    auto name = m_name.to_byte_string();
     char* env_value = getenv(name.characters());
     if (env_value == nullptr)
         return { resolve_slices(shell, Vector { String {} }, m_slices) };
@@ -3933,7 +3933,7 @@ ErrorOr<Vector<String>> TildeValue::resolve_as_list(RefPtr<Shell> shell)
     if (!shell)
         return { resolve_slices(shell, Vector { TRY(builder.to_string()) }, m_slices) };
 
-    return { resolve_slices(shell, Vector { TRY(String::from_deprecated_string(shell->expand_tilde(builder.to_deprecated_string()))) }, m_slices) };
+    return { resolve_slices(shell, Vector { TRY(String::from_byte_string(shell->expand_tilde(builder.to_byte_string()))) }, m_slices) };
 }
 
 ErrorOr<NonnullRefPtr<Rewiring>> CloseRedirection::apply() const
@@ -3956,7 +3956,7 @@ ErrorOr<NonnullRefPtr<Rewiring>> PathRedirection::apply() const
         return adopt_nonnull_ref_or_enomem(new (nothrow) Rewiring(fd, my_fd, Rewiring::Close::Old));
     };
 
-    auto path_string = path.to_deprecated_string();
+    auto path_string = path.to_byte_string();
     switch (direction) {
     case AST::PathRedirection::WriteAppend:
         return check_fd_and_return(open(path_string.characters(), O_WRONLY | O_CREAT | O_APPEND, 0666), path);
diff --git a/Userland/Shell/Builtin.cpp b/Userland/Shell/Builtin.cpp
index c4ed4c9a778..94ccae7bdb1 100644
--- a/Userland/Shell/Builtin.cpp
+++ b/Userland/Shell/Builtin.cpp
@@ -8,7 +8,7 @@
 #include "Formatter.h"
 #include "PosixParser.h"
 #include "Shell.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/ScopeGuard.h>
 #include <AK/Statistics.h>
@@ -98,13 +98,13 @@ ErrorOr<int> Shell::builtin_where(Main::Arguments arguments)
     if (!parser.parse(arguments, Core::ArgsParser::FailureBehavior::PrintUsage))
         return 1;
 
-    auto const look_up_alias = [do_only_path_search, &m_aliases = this->m_aliases](StringView alias) -> Optional<DeprecatedString> {
+    auto const look_up_alias = [do_only_path_search, &m_aliases = this->m_aliases](StringView alias) -> Optional<ByteString> {
         if (do_only_path_search)
             return {};
         return m_aliases.get(alias);
     };
 
-    auto const look_up_builtin = [do_only_path_search](StringView builtin) -> Optional<DeprecatedString> {
+    auto const look_up_builtin = [do_only_path_search](StringView builtin) -> Optional<ByteString> {
         if (do_only_path_search)
             return {};
         for (auto const& _builtin : builtin_names) {
@@ -162,7 +162,7 @@ ErrorOr<int> Shell::builtin_reset(Main::Arguments)
 
 ErrorOr<int> Shell::builtin_alias(Main::Arguments arguments)
 {
-    Vector<DeprecatedString> aliases;
+    Vector<ByteString> aliases;
 
     Core::ArgsParser parser;
     parser.add_positional_argument(aliases, "List of name[=values]'s", "name[=value]", Core::ArgsParser::Required::No);
@@ -198,7 +198,7 @@ ErrorOr<int> Shell::builtin_alias(Main::Arguments arguments)
 ErrorOr<int> Shell::builtin_unalias(Main::Arguments arguments)
 {
     bool remove_all { false };
-    Vector<DeprecatedString> aliases;
+    Vector<ByteString> aliases;
 
     Core::ArgsParser parser;
     parser.set_general_help("Remove alias from the list of aliases");
@@ -371,7 +371,7 @@ ErrorOr<String> Shell::serialize_function_definition(ShellFunction const& fn) co
 
 ErrorOr<int> Shell::builtin_type(Main::Arguments arguments)
 {
-    Vector<DeprecatedString> commands;
+    Vector<ByteString> commands;
     bool dont_show_function_source = false;
 
     Core::ArgsParser parser;
@@ -434,7 +434,7 @@ ErrorOr<int> Shell::builtin_cd(Main::Arguments arguments)
     if (!parser.parse(arguments, Core::ArgsParser::FailureBehavior::PrintUsage))
         return 1;
 
-    DeprecatedString new_path;
+    ByteString new_path;
 
     if (arg_path.is_empty()) {
         new_path = home;
@@ -454,7 +454,7 @@ ErrorOr<int> Shell::builtin_cd(Main::Arguments arguments)
         warnln("Invalid path '{}'", new_path);
         return 1;
     }
-    auto real_path = real_path_or_error.release_value().to_deprecated_string();
+    auto real_path = real_path_or_error.release_value().to_byte_string();
 
     if (cd_history.is_empty() || cd_history.last() != real_path)
         cd_history.enqueue(real_path);
@@ -520,7 +520,7 @@ ErrorOr<int> Shell::builtin_dirs(Main::Arguments arguments)
     bool number_when_printing = false;
     char separator = ' ';
 
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
 
     Core::ArgsParser parser;
     parser.add_option(clear, "Clear the directory stack", "clear", 'c');
@@ -627,7 +627,7 @@ ErrorOr<int> Shell::builtin_exit(Main::Arguments arguments)
 
 ErrorOr<int> Shell::builtin_export(Main::Arguments arguments)
 {
-    Vector<DeprecatedString> vars;
+    Vector<ByteString> vars;
 
     Core::ArgsParser parser;
     parser.add_positional_argument(vars, "List of variable[=value]'s", "values", Core::ArgsParser::Required::No);
@@ -654,7 +654,7 @@ ErrorOr<int> Shell::builtin_export(Main::Arguments arguments)
                 auto values = TRY(const_cast<AST::Value&>(*value).resolve_as_list(*this));
                 StringBuilder builder;
                 builder.join(' ', values);
-                parts.append(builder.to_deprecated_string());
+                parts.append(builder.to_byte_string());
             } else {
                 // Ignore the export.
                 continue;
@@ -677,7 +677,7 @@ ErrorOr<int> Shell::builtin_export(Main::Arguments arguments)
 
 ErrorOr<int> Shell::builtin_glob(Main::Arguments arguments)
 {
-    Vector<DeprecatedString> globs;
+    Vector<ByteString> globs;
     Core::ArgsParser parser;
     parser.add_positional_argument(globs, "Globs to resolve", "glob");
 
@@ -907,8 +907,8 @@ ErrorOr<int> Shell::builtin_pushd(Main::Arguments arguments)
             return 1;
         }
 
-        DeprecatedString dir1 = directory_stack.take_first();
-        DeprecatedString dir2 = directory_stack.take_first();
+        ByteString dir1 = directory_stack.take_first();
+        ByteString dir2 = directory_stack.take_first();
         directory_stack.insert(0, dir2);
         directory_stack.insert(1, dir1);
 
@@ -949,7 +949,7 @@ ErrorOr<int> Shell::builtin_pushd(Main::Arguments arguments)
         }
     }
 
-    auto real_path = LexicalPath::canonicalized_path(path_builder.to_deprecated_string());
+    auto real_path = LexicalPath::canonicalized_path(path_builder.to_byte_string());
 
     struct stat st;
     int rc = stat(real_path.characters(), &st);
@@ -1134,7 +1134,7 @@ ErrorOr<int> Shell::builtin_time(Main::Arguments arguments)
 
         warnln("Timing report: {} ms", iteration_times.sum());
         warnln("==============");
-        warnln("Command:         {}", DeprecatedString::join(' ', arguments.strings));
+        warnln("Command:         {}", ByteString::join(' ', arguments.strings));
         warnln("Average time:    {:.2} ms (median: {}, stddev: {:.2}, min: {}, max:{})",
             iteration_times.average(), iteration_times.median(),
             iteration_times.standard_deviation(),
@@ -1283,7 +1283,7 @@ ErrorOr<int> Shell::builtin_wait(Main::Arguments arguments)
 
 ErrorOr<int> Shell::builtin_unset(Main::Arguments arguments)
 {
-    Vector<DeprecatedString> vars;
+    Vector<ByteString> vars;
     bool unset_only_variables = false; // POSIX only.
 
     Core::ArgsParser parser;
@@ -1321,7 +1321,7 @@ ErrorOr<int> Shell::builtin_set(Main::Arguments arguments)
         for (auto& frame : m_local_frames) {
             for (auto& var : frame->local_variables) {
                 builder.join(" "sv, TRY(var.value->resolve_as_list(*this)));
-                vars.set(TRY(String::from_deprecated_string(var.key)), TRY(builder.to_string()));
+                vars.set(TRY(String::from_byte_string(var.key)), TRY(builder.to_string()));
                 builder.clear();
             }
         }
@@ -1518,11 +1518,11 @@ ErrorOr<int> Shell::builtin_argsparser_parse(Main::Arguments arguments)
 
     Vector<StringView> descriptors;
     Variant<Core::ArgsParser::Option, Core::ArgsParser::Arg, Empty> current;
-    DeprecatedString help_string_storage;
-    DeprecatedString long_name_storage;
-    DeprecatedString value_name_storage;
-    DeprecatedString name_storage;
-    DeprecatedString current_variable;
+    ByteString help_string_storage;
+    ByteString long_name_storage;
+    ByteString value_name_storage;
+    ByteString name_storage;
+    ByteString current_variable;
     // if max > 1 or min < 1, or explicit `--list`.
     bool treat_arg_as_list = false;
     enum class Type {
@@ -1556,7 +1556,7 @@ ErrorOr<int> Shell::builtin_argsparser_parse(Main::Arguments arguments)
             warnln("Invalid value for type u32|size: {}", value);
             return OptionalNone {};
         case Type::Double: {
-            DeprecatedString string = value;
+            ByteString string = value;
             char* endptr = nullptr;
             auto number = strtod(string.characters(), &endptr);
             if (endptr != string.characters() + string.length()) {
@@ -1938,7 +1938,7 @@ ErrorOr<int> Shell::builtin_argsparser_parse(Main::Arguments arguments)
 ErrorOr<int> Shell::builtin_read(Main::Arguments arguments)
 {
     bool no_escape = false;
-    Vector<DeprecatedString> variables;
+    Vector<ByteString> variables;
 
     Core::ArgsParser parser;
     parser.add_option(no_escape, "Do not interpret backslash escapes", "no-escape", 'r');
@@ -2023,7 +2023,7 @@ ErrorOr<int> Shell::builtin_read(Main::Arguments arguments)
 
 ErrorOr<int> Shell::builtin_run_with_env(Main::Arguments arguments)
 {
-    Vector<DeprecatedString> environment_variables;
+    Vector<ByteString> environment_variables;
     Vector<StringView> command_and_arguments;
 
     Core::ArgsParser parser;
@@ -2046,7 +2046,7 @@ ErrorOr<int> Shell::builtin_run_with_env(Main::Arguments arguments)
 
     auto commands = TRY(expand_aliases({ move(command) }));
 
-    HashMap<DeprecatedString, Optional<DeprecatedString>> old_environment_entries;
+    HashMap<ByteString, Optional<ByteString>> old_environment_entries;
     for (auto& variable : environment_variables) {
         auto parts = variable.split_limit('=', 2, SplitBehavior::KeepEmpty);
         if (parts.size() != 2) {
@@ -2054,10 +2054,10 @@ ErrorOr<int> Shell::builtin_run_with_env(Main::Arguments arguments)
             return 1;
         }
 
-        DeprecatedString name = parts[0];
-        old_environment_entries.set(name, getenv(name.characters()) ?: Optional<DeprecatedString> {});
+        ByteString name = parts[0];
+        old_environment_entries.set(name, getenv(name.characters()) ?: Optional<ByteString> {});
 
-        DeprecatedString value = parts[1];
+        ByteString value = parts[1];
         setenv(name.characters(), value.characters(), 1);
     }
 
diff --git a/Userland/Shell/Formatter.cpp b/Userland/Shell/Formatter.cpp
index 3ba32ed8ad3..1af84328e0e 100644
--- a/Userland/Shell/Formatter.cpp
+++ b/Userland/Shell/Formatter.cpp
@@ -14,14 +14,14 @@
 
 namespace Shell {
 
-DeprecatedString Formatter::format()
+ByteString Formatter::format()
 {
     auto node = m_root_node ?: (m_parse_as_posix ? Posix::Parser(m_source).parse() : Parser(m_source).parse());
     if (m_cursor >= 0)
         m_output_cursor = m_cursor;
 
     if (!node)
-        return DeprecatedString();
+        return ByteString();
 
     if (node->is_syntax_error())
         return m_source;
@@ -45,7 +45,7 @@ DeprecatedString Formatter::format()
     if (!string.ends_with(' '))
         current_builder().append(m_trivia);
 
-    return current_builder().to_deprecated_string();
+    return current_builder().to_byte_string();
 }
 
 void Formatter::with_added_indent(int indent, Function<void()> callback)
@@ -67,11 +67,11 @@ void Formatter::in_new_block(Function<void()> callback)
     current_builder().append('}');
 }
 
-DeprecatedString Formatter::in_new_builder(Function<void()> callback, StringBuilder new_builder)
+ByteString Formatter::in_new_builder(Function<void()> callback, StringBuilder new_builder)
 {
     m_builders.append(move(new_builder));
     callback();
-    return m_builders.take_last().to_deprecated_string();
+    return m_builders.take_last().to_byte_string();
 }
 
 void Formatter::test_and_update_output_cursor(const AST::Node* node)
@@ -598,7 +598,7 @@ void Formatter::visit(const AST::MatchExpr* node)
                         if (!first)
                             current_builder().append(" | "sv);
                         first = false;
-                        auto node = make_ref_counted<AST::BarewordLiteral>(AST::Position {}, String::from_deprecated_string(option.pattern_value).release_value_but_fixme_should_propagate_errors());
+                        auto node = make_ref_counted<AST::BarewordLiteral>(AST::Position {}, String::from_byte_string(option.pattern_value).release_value_but_fixme_should_propagate_errors());
                         node->visit(*this);
                     }
                 });
diff --git a/Userland/Shell/Formatter.h b/Userland/Shell/Formatter.h
index 00e29bf889f..da3117d0784 100644
--- a/Userland/Shell/Formatter.h
+++ b/Userland/Shell/Formatter.h
@@ -8,7 +8,7 @@
 
 #include "AST.h"
 #include "NodeVisitor.h"
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Forward.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
@@ -43,7 +43,7 @@ public:
     {
     }
 
-    DeprecatedString format();
+    ByteString format();
     size_t cursor() const { return m_output_cursor; }
 
 private:
@@ -99,7 +99,7 @@ private:
 
     ALWAYS_INLINE void with_added_indent(int indent, Function<void()>);
     ALWAYS_INLINE void in_new_block(Function<void()>);
-    ALWAYS_INLINE DeprecatedString in_new_builder(Function<void()>, StringBuilder new_builder = StringBuilder {});
+    ALWAYS_INLINE ByteString in_new_builder(Function<void()>, StringBuilder new_builder = StringBuilder {});
 
     StringBuilder& current_builder() { return m_builders.last(); }
 
@@ -125,7 +125,7 @@ private:
     const AST::Node* m_last_visited_node { nullptr };
 
     StringView m_trivia;
-    Vector<DeprecatedString> m_heredocs_to_append_after_sequence;
+    Vector<ByteString> m_heredocs_to_append_after_sequence;
 
     bool m_parse_as_posix { false };
 };
diff --git a/Userland/Shell/ImmediateFunctions.cpp b/Userland/Shell/ImmediateFunctions.cpp
index bdb76c280de..fb43bd7ea64 100644
--- a/Userland/Shell/ImmediateFunctions.cpp
+++ b/Userland/Shell/ImmediateFunctions.cpp
@@ -15,7 +15,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_length_impl(AST::ImmediateExpression
 {
     auto name = across ? "length_across" : "length";
     if (arguments.size() < 1 || arguments.size() > 2) {
-        raise_error(ShellError::EvaluatedSyntaxError, DeprecatedString::formatted("Expected one or two arguments to `{}'", name), invoking_node.position());
+        raise_error(ShellError::EvaluatedSyntaxError, ByteString::formatted("Expected one or two arguments to `{}'", name), invoking_node.position());
         return nullptr;
     }
 
@@ -34,7 +34,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_length_impl(AST::ImmediateExpression
 
         auto& mode_arg = arguments.first();
         if (!mode_arg->is_bareword()) {
-            raise_error(ShellError::EvaluatedSyntaxError, DeprecatedString::formatted("Expected a bareword (either 'string' or 'list') in the two-argument form of the `{}' immediate", name), mode_arg->position());
+            raise_error(ShellError::EvaluatedSyntaxError, ByteString::formatted("Expected a bareword (either 'string' or 'list') in the two-argument form of the `{}' immediate", name), mode_arg->position());
             return nullptr;
         }
 
@@ -46,7 +46,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_length_impl(AST::ImmediateExpression
         } else if (mode_name == "infer") {
             mode = Infer;
         } else {
-            raise_error(ShellError::EvaluatedSyntaxError, DeprecatedString::formatted("Expected either 'string' or 'list' (and not {}) in the two-argument form of the `{}' immediate", mode_name, name), mode_arg->position());
+            raise_error(ShellError::EvaluatedSyntaxError, ByteString::formatted("Expected either 'string' or 'list' (and not {}) in the two-argument form of the `{}' immediate", mode_name, name), mode_arg->position());
             return nullptr;
         }
 
@@ -127,7 +127,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_length_impl(AST::ImmediateExpression
 
                 if (is_inferred) {
                     raise_error(ShellError::EvaluatedSyntaxError,
-                        DeprecatedString::formatted("Could not infer expression type, please explicitly use `{0} string' or `{0} list'", name),
+                        ByteString::formatted("Could not infer expression type, please explicitly use `{0} string' or `{0} list'", name),
                         invoking_node.position());
                     return nullptr;
                 }
@@ -136,7 +136,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_length_impl(AST::ImmediateExpression
                 raise_error(ShellError::EvaluatedSyntaxError,
                     source.is_empty()
                         ? "Invalid application of `length' to a list"
-                        : DeprecatedString::formatted("Invalid application of `length' to a list\nperhaps you meant `{1}length \"{0}\"{2}' or `{1}length_across {0}{2}'?", source, "\x1b[32m", "\x1b[0m"),
+                        : ByteString::formatted("Invalid application of `length' to a list\nperhaps you meant `{1}length \"{0}\"{2}' or `{1}length_across {0}{2}'?", source, "\x1b[32m", "\x1b[0m"),
                     expr_node->position());
                 return nullptr;
             }
@@ -160,7 +160,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_length_impl(AST::ImmediateExpression
 
             auto source = formatter.format();
             raise_error(ShellError::EvaluatedSyntaxError,
-                DeprecatedString::formatted("Invalid application of `length_across' to a non-list\nperhaps you meant `{1}length {0}{2}'?", source, "\x1b[32m", "\x1b[0m"),
+                ByteString::formatted("Invalid application of `length_across' to a non-list\nperhaps you meant `{1}length {0}{2}'?", source, "\x1b[32m", "\x1b[0m"),
                 expr_node->position());
             return nullptr;
         }
@@ -226,13 +226,13 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_regex_replace(AST::ImmediateExpressi
         return nullptr;
     }
 
-    Regex<PosixExtendedParser> re { TRY(pattern->resolve_as_list(this)).first().to_deprecated_string() };
+    Regex<PosixExtendedParser> re { TRY(pattern->resolve_as_list(this)).first().to_byte_string() };
     auto result = re.replace(
         TRY(value->resolve_as_list(this))[0],
         TRY(replacement->resolve_as_list(this))[0],
         PosixFlags::Global | PosixFlags::Multiline | PosixFlags::Unicode);
 
-    return AST::make_ref_counted<AST::StringLiteral>(invoking_node.position(), TRY(String::from_deprecated_string(result)), AST::StringLiteral::EnclosureType::None);
+    return AST::make_ref_counted<AST::StringLiteral>(invoking_node.position(), TRY(String::from_byte_string(result)), AST::StringLiteral::EnclosureType::None);
 }
 
 ErrorOr<RefPtr<AST::Node>> Shell::immediate_remove_suffix(AST::ImmediateExpression& invoking_node, Vector<NonnullRefPtr<AST::Node>> const& arguments)
@@ -484,7 +484,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_assign_default(AST::ImmediateExpress
         return make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 
     auto value = TRY(TRY(const_cast<AST::Node&>(*arguments.last()).run(*this))->resolve_without_cast(*this));
-    set_local_variable(name.to_deprecated_string(), value);
+    set_local_variable(name.to_byte_string(), value);
 
     return make_ref_counted<AST::SyntheticNode>(invoking_node.position(), value);
 }
@@ -553,7 +553,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_assign_defined_default(AST::Immediat
         return make_ref_counted<AST::SimpleVariable>(invoking_node.position(), name);
 
     auto value = TRY(TRY(const_cast<AST::Node&>(*arguments.last()).run(*this))->resolve_without_cast(*this));
-    set_local_variable(name.to_deprecated_string(), value);
+    set_local_variable(name.to_byte_string(), value);
 
     return make_ref_counted<AST::SyntheticNode>(invoking_node.position(), value);
 }
@@ -1231,7 +1231,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_math(AST::ImmediateExpression& invok
         case U'\r':
             break;
         default:
-            raise_error(ShellError::EvaluatedSyntaxError, DeprecatedString::formatted("Unexpected character '{:c}' in math expression", code_point), arguments.first()->position());
+            raise_error(ShellError::EvaluatedSyntaxError, ByteString::formatted("Unexpected character '{:c}' in math expression", code_point), arguments.first()->position());
             return nullptr;
         }
     }
@@ -1268,7 +1268,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_math(AST::ImmediateExpression& invok
                 }
 
                 if (resolution_attempts_remaining == 0)
-                    raise_error(ShellError::EvaluatedSyntaxError, DeprecatedString::formatted("Too many indirections when resolving variable '{}'", name), arguments.first()->position());
+                    raise_error(ShellError::EvaluatedSyntaxError, ByteString::formatted("Too many indirections when resolving variable '{}'", name), arguments.first()->position());
 
                 return 0;
             },
@@ -1296,7 +1296,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_math(AST::ImmediateExpression& invok
                         }));
                     }
 
-                    set_local_variable(name->to_deprecated_string(), make_ref_counted<AST::StringValue>(TRY(String::number(rhs))));
+                    set_local_variable(name->to_byte_string(), make_ref_counted<AST::StringValue>(TRY(String::number(rhs))));
                     return rhs;
                 }
 
@@ -1372,7 +1372,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::immediate_math(AST::ImmediateExpression& invok
                 return TRY(interpret(node->false_value));
             },
             [&](NonnullOwnPtr<Arithmetic::ErrorNode> const& node) -> ErrorOr<i64> {
-                raise_error(ShellError::EvaluatedSyntaxError, node->error.to_deprecated_string(), arguments.first()->position());
+                raise_error(ShellError::EvaluatedSyntaxError, node->error.to_byte_string(), arguments.first()->position());
                 return 0;
             });
     };
@@ -1391,7 +1391,7 @@ ErrorOr<RefPtr<AST::Node>> Shell::run_immediate_function(StringView str, AST::Im
     ENUMERATE_SHELL_IMMEDIATE_FUNCTIONS()
 
 #undef __ENUMERATE_SHELL_IMMEDIATE_FUNCTION
-    raise_error(ShellError::EvaluatedSyntaxError, DeprecatedString::formatted("Unknown immediate function {}", str), invoking_node.position());
+    raise_error(ShellError::EvaluatedSyntaxError, ByteString::formatted("Unknown immediate function {}", str), invoking_node.position());
     return nullptr;
 }
 
diff --git a/Userland/Shell/Job.cpp b/Userland/Shell/Job.cpp
index 919b0593a82..cfc37707932 100644
--- a/Userland/Shell/Job.cpp
+++ b/Userland/Shell/Job.cpp
@@ -63,7 +63,7 @@ bool Job::print_status(PrintStatusMode mode)
     return true;
 }
 
-Job::Job(pid_t pid, unsigned pgid, DeprecatedString cmd, u64 job_id, AST::Command&& command)
+Job::Job(pid_t pid, unsigned pgid, ByteString cmd, u64 job_id, AST::Command&& command)
     : m_pgid(pgid)
     , m_pid(pid)
     , m_job_id(job_id)
diff --git a/Userland/Shell/Job.h b/Userland/Shell/Job.h
index 3f40973d3dd..26907ca5955 100644
--- a/Userland/Shell/Job.h
+++ b/Userland/Shell/Job.h
@@ -8,8 +8,8 @@
 
 #include "Execution.h"
 #include "Forward.h"
+#include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Function.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonValue.h>
@@ -23,7 +23,7 @@ struct LocalFrame;
 
 class Job : public RefCounted<Job> {
 public:
-    static NonnullRefPtr<Job> create(pid_t pid, pid_t pgid, DeprecatedString cmd, u64 job_id, AST::Command&& command) { return adopt_ref(*new Job(pid, pgid, move(cmd), job_id, move(command))); }
+    static NonnullRefPtr<Job> create(pid_t pid, pid_t pgid, ByteString cmd, u64 job_id, AST::Command&& command) { return adopt_ref(*new Job(pid, pgid, move(cmd), job_id, move(command))); }
 
     ~Job()
     {
@@ -40,7 +40,7 @@ public:
 
     pid_t pgid() const { return m_pgid; }
     pid_t pid() const { return m_pid; }
-    DeprecatedString const& cmd() const { return m_cmd; }
+    ByteString const& cmd() const { return m_cmd; }
     const AST::Command& command() const { return *m_command; }
     AST::Command* command_ptr() { return m_command; }
     u64 job_id() const { return m_job_id; }
@@ -92,12 +92,12 @@ public:
     bool print_status(PrintStatusMode);
 
 private:
-    Job(pid_t pid, unsigned pgid, DeprecatedString cmd, u64 job_id, AST::Command&& command);
+    Job(pid_t pid, unsigned pgid, ByteString cmd, u64 job_id, AST::Command&& command);
 
     pid_t m_pgid { 0 };
     pid_t m_pid { 0 };
     u64 m_job_id { 0 };
-    DeprecatedString m_cmd;
+    ByteString m_cmd;
     bool m_exited { false };
     bool m_running_in_background { false };
     bool m_should_announce_exit { false };
diff --git a/Userland/Shell/Parser.cpp b/Userland/Shell/Parser.cpp
index 06f73c49e56..011f748bfe3 100644
--- a/Userland/Shell/Parser.cpp
+++ b/Userland/Shell/Parser.cpp
@@ -1069,7 +1069,7 @@ AST::MatchEntry Parser::parse_match_entry()
             if (names.is_empty()) {
                 for (auto& name : regex.parser_result.capture_groups)
                     names.append(TRY_OR(
-                        String::from_deprecated_string(name),
+                        String::from_byte_string(name),
                         error = create<AST::SyntaxError>(MUST(String::from_utf8(_error.string_literal())));
                         break;));
             } else {
@@ -1077,7 +1077,7 @@ AST::MatchEntry Parser::parse_match_entry()
                 for (auto& name : regex.parser_result.capture_groups) {
                     if (names.size() <= index) {
                         names.append(TRY_OR(
-                            String::from_deprecated_string(name),
+                            String::from_byte_string(name),
                             error = create<AST::SyntaxError>(MUST(String::from_utf8(_error.string_literal())));
                             break;));
                         continue;
diff --git a/Userland/Shell/PosixLexer.cpp b/Userland/Shell/PosixLexer.cpp
index 28afbacd26a..bbadbd841b2 100644
--- a/Userland/Shell/PosixLexer.cpp
+++ b/Userland/Shell/PosixLexer.cpp
@@ -598,7 +598,7 @@ ErrorOr<Lexer::ReductionResult> Lexer::reduce_start()
     if (m_state.escaping && consume_specific('\n')) {
         m_state.escaping = false;
 
-        auto buffer = m_state.buffer.to_deprecated_string().substring(0, m_state.buffer.length() - 1);
+        auto buffer = m_state.buffer.to_byte_string().substring(0, m_state.buffer.length() - 1);
         m_state.buffer.clear();
         m_state.buffer.append(buffer);
 
diff --git a/Userland/Shell/PosixLexer.h b/Userland/Shell/PosixLexer.h
index 24d6b0d1028..08eaecd246f 100644
--- a/Userland/Shell/PosixLexer.h
+++ b/Userland/Shell/PosixLexer.h
@@ -93,7 +93,7 @@ struct ResolvedParameterExpansion {
         Word,
     } expand { Expand::Nothing };
 
-    DeprecatedString to_deprecated_string() const
+    ByteString to_byte_string() const
     {
         StringBuilder builder;
         builder.append("{"sv);
@@ -171,7 +171,7 @@ struct ResolvedParameterExpansion {
         builder.append(argument);
         builder.append(")"sv);
         builder.append("}"sv);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 };
 
diff --git a/Userland/Shell/PosixParser.cpp b/Userland/Shell/PosixParser.cpp
index e88d99ba238..6ecea0a5d12 100644
--- a/Userland/Shell/PosixParser.cpp
+++ b/Userland/Shell/PosixParser.cpp
@@ -144,20 +144,20 @@ ErrorOr<void> Parser::fill_token_buffer(Optional<Reduction> starting_reduction)
         if (!token.has_value())
             break;
 #if SHELL_POSIX_PARSER_DEBUG
-        DeprecatedString position = "(~)";
+        ByteString position = "(~)";
         if (token->position.has_value())
-            position = DeprecatedString::formatted("{}:{}", token->position->start_offset, token->position->end_offset);
-        DeprecatedString expansions = "";
+            position = ByteString::formatted("{}:{}", token->position->start_offset, token->position->end_offset);
+        ByteString expansions = "";
         for (auto& exp : token->resolved_expansions)
             exp.visit(
-                [&](ResolvedParameterExpansion& x) { expansions = DeprecatedString::formatted("{}param({}),", expansions, x.to_deprecated_string()); },
-                [&](ResolvedCommandExpansion& x) { expansions = DeprecatedString::formatted("{}command({:p})", expansions, x.command.ptr()); },
-                [&](ResolvedArithmeticExpansion& x) { expansions = DeprecatedString::formatted("{}arith({})", expansions, x.source_expression); });
-        DeprecatedString rexpansions = "";
+                [&](ResolvedParameterExpansion& x) { expansions = ByteString::formatted("{}param({}),", expansions, x.to_byte_string()); },
+                [&](ResolvedCommandExpansion& x) { expansions = ByteString::formatted("{}command({:p})", expansions, x.command.ptr()); },
+                [&](ResolvedArithmeticExpansion& x) { expansions = ByteString::formatted("{}arith({})", expansions, x.source_expression); });
+        ByteString rexpansions = "";
         for (auto& exp : token->expansions)
             exp.visit(
-                [&](ParameterExpansion& x) { rexpansions = DeprecatedString::formatted("{}param({}) from {} to {},", rexpansions, x.parameter.string_view(), x.range.start, x.range.length); },
-                [&](auto&) { rexpansions = DeprecatedString::formatted("{}...,", rexpansions); });
+                [&](ParameterExpansion& x) { rexpansions = ByteString::formatted("{}param({}) from {} to {},", rexpansions, x.parameter.string_view(), x.range.start, x.range.length); },
+                [&](auto&) { rexpansions = ByteString::formatted("{}...,", rexpansions); });
         dbgln("Token @ {}: '{}' (type {}) - parsed expansions: {} - raw expansions: {}", position, token->value.replace("\n"sv, "\\n"sv, ReplaceMode::All), token->type_name(), expansions, rexpansions);
 #endif
     }
@@ -1845,7 +1845,7 @@ ErrorOr<RefPtr<AST::Node>> Parser::parse_word()
     for (auto& expansion : token.resolved_expansions) {
         TRY(expansion.visit(
             [&](ResolvedParameterExpansion const& x) -> ErrorOr<void> {
-                dbgln_if(SHELL_POSIX_PARSER_DEBUG, "    Expanding '{}' ({}+{})", x.to_deprecated_string(), x.range.start, x.range.length);
+                dbgln_if(SHELL_POSIX_PARSER_DEBUG, "    Expanding '{}' ({}+{})", x.to_byte_string(), x.range.start, x.range.length);
                 if (x.range.start >= value_bytes.length()) {
                     dbgln("Parameter expansion range {}-{} is out of bounds for '{}'", x.range.start, x.range.length, value_bytes);
                     return {};
diff --git a/Userland/Shell/PosixParser.h b/Userland/Shell/PosixParser.h
index b6d4f6b41b7..3f3028570d8 100644
--- a/Userland/Shell/PosixParser.h
+++ b/Userland/Shell/PosixParser.h
@@ -30,7 +30,7 @@ public:
     RefPtr<AST::Node> parse_word_list(AllowNewlines = AllowNewlines::No);
 
     struct Error {
-        DeprecatedString message;
+        ByteString message;
         Optional<AST::Position> position;
     };
     auto& errors() const { return m_errors; }
@@ -106,7 +106,7 @@ private:
     void error(Token const& token, CheckedFormatString<Ts...> fmt, Ts&&... args)
     {
         m_errors.append(Error {
-            DeprecatedString::formatted(fmt.view(), forward<Ts>(args)...),
+            ByteString::formatted(fmt.view(), forward<Ts>(args)...),
             token.position,
         });
     }
diff --git a/Userland/Shell/Shell.cpp b/Userland/Shell/Shell.cpp
index 452bb750148..e80d1d72dd9 100644
--- a/Userland/Shell/Shell.cpp
+++ b/Userland/Shell/Shell.cpp
@@ -80,7 +80,7 @@ void Shell::print_path(StringView path)
     out("\033]8;;{}\033\\{}\033]8;;\033\\", url.serialize(), path);
 }
 
-DeprecatedString Shell::prompt() const
+ByteString Shell::prompt() const
 {
     if (m_next_scheduled_prompt_text.has_value())
         return m_next_scheduled_prompt_text.release_value();
@@ -93,7 +93,7 @@ DeprecatedString Shell::prompt() const
         StringBuilder builder;
         builder.appendff("\033]0;{}@{}:{}\007", username, hostname, cwd);
         builder.appendff("\033[31;1m{}\033[0m@\033[37;1m{}\033[0m:\033[32;1m{}\033[0m$> ", username, hostname, cwd);
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
 
     StringBuilder builder;
@@ -121,7 +121,7 @@ DeprecatedString Shell::prompt() const
             builder.append({ hostname, strlen(hostname) });
 
         } else if (lexer.consume_specific('w') || lexer.consume_specific('W')) {
-            DeprecatedString const home_path = getenv("HOME");
+            ByteString const home_path = getenv("HOME");
             if (cwd.starts_with(home_path)) {
                 builder.append('~');
                 builder.append(cwd.substring_view(home_path.length(), cwd.length() - home_path.length()));
@@ -139,7 +139,7 @@ DeprecatedString Shell::prompt() const
 
             auto const max_component_count = number_string.to_uint().value();
 
-            DeprecatedString const home_path = getenv("HOME");
+            ByteString const home_path = getenv("HOME");
 
             auto const should_collapse_path = cwd.starts_with(home_path);
             auto const should_use_ellipsis = (next_char == 'w');
@@ -172,13 +172,13 @@ DeprecatedString Shell::prompt() const
             builder.append(uid == 0 ? '#' : '$');
 
         } else if (lexer.consume_specific('t')) {
-            builder.append(Core::DateTime::now().to_deprecated_string("%H:%M:%S"sv));
+            builder.append(Core::DateTime::now().to_byte_string("%H:%M:%S"sv));
 
         } else if (lexer.consume_specific('T')) {
-            builder.append(Core::DateTime::now().to_deprecated_string("%I:%M:%S"sv));
+            builder.append(Core::DateTime::now().to_byte_string("%I:%M:%S"sv));
 
         } else if (lexer.consume_specific('@')) {
-            builder.append(Core::DateTime::now().to_deprecated_string("%I:%M %p"sv));
+            builder.append(Core::DateTime::now().to_byte_string("%I:%M %p"sv));
 
         } else if (lexer.consume_specific("D{"sv)) {
             auto format = lexer.consume_until('}');
@@ -187,7 +187,7 @@ DeprecatedString Shell::prompt() const
 
             if (format.is_empty())
                 format = "%y-%m-%d"sv;
-            builder.append(Core::DateTime::now().to_deprecated_string(format));
+            builder.append(Core::DateTime::now().to_byte_string(format));
 
         } else if (lexer.consume_specific('j')) {
             builder.appendff("{}", jobs.size());
@@ -205,10 +205,10 @@ DeprecatedString Shell::prompt() const
             lexer.consume();
         }
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Shell::expand_tilde(StringView expression)
+ByteString Shell::expand_tilde(StringView expression)
 {
     VERIFY(expression.starts_with('~'));
 
@@ -231,17 +231,17 @@ DeprecatedString Shell::expand_tilde(StringView expression)
         if (!home) {
             auto passwd = getpwuid(getuid());
             VERIFY(passwd && passwd->pw_dir);
-            return DeprecatedString::formatted("{}/{}", passwd->pw_dir, path.to_deprecated_string());
+            return ByteString::formatted("{}/{}", passwd->pw_dir, path.to_byte_string());
         }
-        return DeprecatedString::formatted("{}/{}", home, path.to_deprecated_string());
+        return ByteString::formatted("{}/{}", home, path.to_byte_string());
     }
 
-    auto passwd = getpwnam(login_name.to_deprecated_string().characters());
+    auto passwd = getpwnam(login_name.to_byte_string().characters());
     if (!passwd)
         return expression;
     VERIFY(passwd->pw_dir);
 
-    return DeprecatedString::formatted("{}/{}", passwd->pw_dir, path.to_deprecated_string());
+    return ByteString::formatted("{}/{}", passwd->pw_dir, path.to_byte_string());
 }
 
 bool Shell::is_glob(StringView s)
@@ -254,7 +254,7 @@ bool Shell::is_glob(StringView s)
     return false;
 }
 
-ErrorOr<Vector<DeprecatedString>> Shell::expand_globs(StringView path, StringView base)
+ErrorOr<Vector<ByteString>> Shell::expand_globs(StringView path, StringView base)
 {
     auto explicitly_set_base = false;
     if (path.starts_with('/')) {
@@ -288,10 +288,10 @@ ErrorOr<Vector<DeprecatedString>> Shell::expand_globs(StringView path, StringVie
     return results;
 }
 
-Vector<DeprecatedString> Shell::expand_globs(Vector<StringView> path_segments, StringView base)
+Vector<ByteString> Shell::expand_globs(Vector<StringView> path_segments, StringView base)
 {
     if (path_segments.is_empty()) {
-        DeprecatedString base_str = base;
+        ByteString base_str = base;
         struct stat statbuf;
         if (lstat(base_str.characters(), &statbuf) < 0)
             return {};
@@ -300,7 +300,7 @@ Vector<DeprecatedString> Shell::expand_globs(Vector<StringView> path_segments, S
 
     auto first_segment = path_segments.take_first();
     if (is_glob(first_segment)) {
-        Vector<DeprecatedString> result;
+        Vector<ByteString> result;
 
         auto const is_glob_directory = first_segment.ends_with('/');
         if (is_glob_directory)
@@ -389,12 +389,12 @@ ErrorOr<Vector<AST::Command>> Shell::expand_aliases(Vector<AST::Command> initial
     return commands;
 }
 
-DeprecatedString Shell::resolve_path(DeprecatedString path) const
+ByteString Shell::resolve_path(ByteString path) const
 {
     if (!path.starts_with('/'))
-        path = DeprecatedString::formatted("{}/{}", cwd, path);
+        path = ByteString::formatted("{}/{}", cwd, path);
 
-    return FileSystem::real_path(path).release_value_but_fixme_should_propagate_errors().to_deprecated_string();
+    return FileSystem::real_path(path).release_value_but_fixme_should_propagate_errors().to_byte_string();
 }
 
 Shell::LocalFrame* Shell::find_frame_containing_local_variable(StringView name)
@@ -421,7 +421,7 @@ ErrorOr<RefPtr<AST::Value const>> Shell::look_up_local_variable(StringView name)
 ErrorOr<RefPtr<AST::Value const>> Shell::get_argument(size_t index) const
 {
     if (index == 0) {
-        auto current_script_string = TRY(String::from_deprecated_string(current_script));
+        auto current_script_string = TRY(String::from_byte_string(current_script));
         return adopt_ref(*new AST::StringValue(current_script_string));
     }
 
@@ -444,18 +444,18 @@ ErrorOr<RefPtr<AST::Value const>> Shell::get_argument(size_t index) const
     return nullptr;
 }
 
-ErrorOr<DeprecatedString> Shell::local_variable_or(StringView name, DeprecatedString const& replacement) const
+ErrorOr<ByteString> Shell::local_variable_or(StringView name, ByteString const& replacement) const
 {
     auto value = TRY(look_up_local_variable(name));
     if (value) {
         StringBuilder builder;
         builder.join(' ', TRY(const_cast<AST::Value&>(*value).resolve_as_list(const_cast<Shell&>(*this))));
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     }
     return replacement;
 }
 
-void Shell::set_local_variable(DeprecatedString const& name, RefPtr<AST::Value> value, bool only_in_current_frame)
+void Shell::set_local_variable(ByteString const& name, RefPtr<AST::Value> value, bool only_in_current_frame)
 {
     if (!only_in_current_frame) {
         if (auto* frame = find_frame_containing_local_variable(name)) {
@@ -487,7 +487,7 @@ void Shell::unset_local_variable(StringView name, bool only_in_current_frame)
     m_local_frames.last()->local_variables.remove(name);
 }
 
-void Shell::define_function(DeprecatedString name, Vector<DeprecatedString> argnames, RefPtr<AST::Node> body)
+void Shell::define_function(ByteString name, Vector<ByteString> argnames, RefPtr<AST::Node> body)
 {
     add_entry_to_cache({ RunnablePath::Kind::Function, name });
     m_functions.set(name, { name, move(argnames), move(body) });
@@ -505,7 +505,7 @@ bool Shell::invoke_function(const AST::Command& command, int& retval)
 
     StringView name = command.argv.first();
 
-    TemporaryChange<DeprecatedString> script_change { current_script, name };
+    TemporaryChange<ByteString> script_change { current_script, name };
 
     auto function_option = m_functions.get(name);
     if (!function_option.has_value())
@@ -519,12 +519,12 @@ bool Shell::invoke_function(const AST::Command& command, int& retval)
     }
 
     if (command.argv.size() - 1 < function.arguments.size()) {
-        raise_error(ShellError::EvaluatedSyntaxError, DeprecatedString::formatted("Expected at least {} arguments to {}, but got {}", function.arguments.size(), function.name, command.argv.size() - 1), command.position);
+        raise_error(ShellError::EvaluatedSyntaxError, ByteString::formatted("Expected at least {} arguments to {}, but got {}", function.arguments.size(), function.name, command.argv.size() - 1), command.position);
         retval = 1;
         return true;
     }
 
-    auto frame = push_frame(DeprecatedString::formatted("function {}", function.name), LocalFrameKind::FunctionOrGlobal);
+    auto frame = push_frame(ByteString::formatted("function {}", function.name), LocalFrameKind::FunctionOrGlobal);
     size_t index = 0;
     for (auto& arg : function.arguments) {
         ++index;
@@ -547,7 +547,7 @@ bool Shell::invoke_function(const AST::Command& command, int& retval)
     return true;
 }
 
-DeprecatedString Shell::format(StringView source, ssize_t& cursor) const
+ByteString Shell::format(StringView source, ssize_t& cursor) const
 {
     Formatter formatter(source, cursor, m_in_posix_mode);
     auto result = formatter.format();
@@ -556,7 +556,7 @@ DeprecatedString Shell::format(StringView source, ssize_t& cursor) const
     return result;
 }
 
-Shell::Frame Shell::push_frame(DeprecatedString name, Shell::LocalFrameKind kind)
+Shell::Frame Shell::push_frame(ByteString name, Shell::LocalFrameKind kind)
 {
     m_local_frames.append(make<LocalFrame>(name, decltype(LocalFrame::local_variables) {}, kind));
     dbgln_if(SH_DEBUG, "New frame '{}' at {:p}", name, &m_local_frames.last());
@@ -583,7 +583,7 @@ Shell::Frame::~Frame()
     (void)frames.take_last();
 }
 
-Optional<DeprecatedString> Shell::resolve_alias(StringView name) const
+Optional<ByteString> Shell::resolve_alias(StringView name) const
 {
     return m_aliases.get(name);
 }
@@ -606,7 +606,7 @@ Optional<Shell::RunnablePath> Shell::runnable_path_for(StringView name)
     return *found;
 }
 
-Optional<DeprecatedString> Shell::help_path_for(Vector<RunnablePath> visited, Shell::RunnablePath const& runnable_path)
+Optional<ByteString> Shell::help_path_for(Vector<RunnablePath> visited, Shell::RunnablePath const& runnable_path)
 {
     switch (runnable_path.kind) {
     case RunnablePath::Kind::Executable: {
@@ -806,11 +806,11 @@ ErrorOr<RefPtr<Job>> Shell::run_command(const AST::Command& command)
     }
 
     Vector<char const*> argv;
-    Vector<DeprecatedString> copy_argv;
+    Vector<ByteString> copy_argv;
     argv.ensure_capacity(command.argv.size() + 1);
 
     for (auto& arg : command.argv) {
-        copy_argv.append(arg.to_deprecated_string());
+        copy_argv.append(arg.to_byte_string());
         argv.append(copy_argv.last().characters());
     }
 
@@ -920,7 +920,7 @@ ErrorOr<RefPtr<Job>> Shell::run_command(const AST::Command& command)
     // as the child will run this chain.
     if (command.should_immediately_execute_next)
         command_copy.next_chain.clear();
-    auto job = Job::create(child, pgid, cmd.to_deprecated_string(), find_last_job_id() + 1, move(command_copy));
+    auto job = Job::create(child, pgid, cmd.to_byte_string(), find_last_job_id() + 1, move(command_copy));
     jobs.set((u64)child, job);
 
     job->on_exit = [this](auto job) {
@@ -951,7 +951,7 @@ ErrorOr<RefPtr<Job>> Shell::run_command(const AST::Command& command)
 
 ErrorOr<void> Shell::execute_process(Span<StringView> argv)
 {
-    Vector<DeprecatedString> strings;
+    Vector<ByteString> strings;
     Vector<char const*> args;
     TRY(strings.try_ensure_capacity(argv.size()));
     TRY(args.try_ensure_capacity(argv.size() + 1));
@@ -1016,7 +1016,7 @@ void Shell::execute_process(Vector<char const*>&& argv)
                 if (!line.starts_with("#!"sv))
                     break;
                 GenericLexer shebang_lexer { line.substring_view(2) };
-                auto shebang = shebang_lexer.consume_until(is_any_of("\n\r"sv)).to_deprecated_string();
+                auto shebang = shebang_lexer.consume_until(is_any_of("\n\r"sv)).to_byte_string();
                 argv.prepend(shebang.characters());
                 int rc = execvp(argv[0], const_cast<char* const*>(argv.data()));
                 if (rc < 0) {
@@ -1114,7 +1114,7 @@ Vector<NonnullRefPtr<Job>> Shell::run_commands(Vector<AST::Command>& commands)
         }
         auto job_result = run_command(command);
         if (job_result.is_error()) {
-            raise_error(ShellError::LaunchError, DeprecatedString::formatted("{} while running '{}'", job_result.error(), command.argv.first()), command.position);
+            raise_error(ShellError::LaunchError, ByteString::formatted("{} while running '{}'", job_result.error(), command.argv.first()), command.position);
             break;
         }
 
@@ -1141,7 +1141,7 @@ Vector<NonnullRefPtr<Job>> Shell::run_commands(Vector<AST::Command>& commands)
     return spawned_jobs;
 }
 
-bool Shell::run_file(DeprecatedString const& filename, bool explicitly_invoked)
+bool Shell::run_file(ByteString const& filename, bool explicitly_invoked)
 {
     TemporaryChange script_change { current_script, filename };
     TemporaryChange interactive_change { m_is_interactive, false };
@@ -1149,7 +1149,7 @@ bool Shell::run_file(DeprecatedString const& filename, bool explicitly_invoked)
 
     auto file_or_error = Core::File::open(filename, Core::File::OpenMode::Read);
     if (file_or_error.is_error()) {
-        auto error = DeprecatedString::formatted("'{}': {}", escape_token_for_single_quotes(filename), file_or_error.error());
+        auto error = ByteString::formatted("'{}': {}", escape_token_for_single_quotes(filename), file_or_error.error());
         if (explicitly_invoked)
             raise_error(ShellError::OpenFailure, error);
         else
@@ -1159,7 +1159,7 @@ bool Shell::run_file(DeprecatedString const& filename, bool explicitly_invoked)
     auto file = file_or_error.release_value();
     auto data_or_error = file->read_until_eof();
     if (data_or_error.is_error()) {
-        auto error = DeprecatedString::formatted("'{}': {}", escape_token_for_single_quotes(filename), data_or_error.error());
+        auto error = ByteString::formatted("'{}': {}", escape_token_for_single_quotes(filename), data_or_error.error());
         if (explicitly_invoked)
             raise_error(ShellError::OpenFailure, error);
         else
@@ -1242,14 +1242,14 @@ void Shell::block_on_job(RefPtr<Job> job)
         block_on_pipeline(command->pipeline);
 }
 
-DeprecatedString Shell::get_history_path()
+ByteString Shell::get_history_path()
 {
     if (auto histfile = getenv("HISTFILE"))
         return { histfile };
-    return DeprecatedString::formatted("{}/.history", home);
+    return ByteString::formatted("{}/.history", home);
 }
 
-DeprecatedString Shell::escape_token_for_single_quotes(StringView token)
+ByteString Shell::escape_token_for_single_quotes(StringView token)
 {
     // `foo bar \n '` -> `'foo bar \n '"'"`
 
@@ -1276,10 +1276,10 @@ DeprecatedString Shell::escape_token_for_single_quotes(StringView token)
     if (started_single_quote)
         builder.append("'"sv);
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Shell::escape_token_for_double_quotes(StringView token)
+ByteString Shell::escape_token_for_double_quotes(StringView token)
 {
     // `foo bar \n $x 'blah "hello` -> `"foo bar \\n $x 'blah \"hello"`
 
@@ -1302,7 +1302,7 @@ DeprecatedString Shell::escape_token_for_double_quotes(StringView token)
 
     builder.append('"');
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 Shell::SpecialCharacterEscapeMode Shell::special_character_escape_mode(u32 code_point, EscapeMode mode)
@@ -1346,7 +1346,7 @@ Shell::SpecialCharacterEscapeMode Shell::special_character_escape_mode(u32 code_
 }
 
 template<typename... Offsets>
-static DeprecatedString do_escape(Shell::EscapeMode escape_mode, auto& token, Offsets&... offsets)
+static ByteString do_escape(Shell::EscapeMode escape_mode, auto& token, Offsets&... offsets)
 {
     StringBuilder builder;
     size_t offset_from_original = 0;
@@ -1431,15 +1431,15 @@ static DeprecatedString do_escape(Shell::EscapeMode escape_mode, auto& token, Of
         }
     }
     check_offsets();
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-DeprecatedString Shell::escape_token(Utf32View token, EscapeMode escape_mode)
+ByteString Shell::escape_token(Utf32View token, EscapeMode escape_mode)
 {
     return do_escape(escape_mode, token);
 }
 
-DeprecatedString Shell::escape_token(StringView token, EscapeMode escape_mode)
+ByteString Shell::escape_token(StringView token, EscapeMode escape_mode)
 {
     Utf8View view { token };
     if (view.validate())
@@ -1447,7 +1447,7 @@ DeprecatedString Shell::escape_token(StringView token, EscapeMode escape_mode)
     return do_escape(escape_mode, token);
 }
 
-DeprecatedString Shell::unescape_token(StringView token)
+ByteString Shell::unescape_token(StringView token)
 {
     StringBuilder builder;
 
@@ -1474,7 +1474,7 @@ DeprecatedString Shell::unescape_token(StringView token)
     if (state == Escaped)
         builder.append('\\');
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 void Shell::cache_path()
@@ -1506,14 +1506,14 @@ void Shell::cache_path()
     }
 
     // TODO: Can we make this rely on Core::System::resolve_executable_from_environment()?
-    DeprecatedString path = getenv("PATH");
+    ByteString path = getenv("PATH");
     if (!path.is_empty()) {
         auto directories = path.split(':');
         for (auto const& directory : directories) {
             Core::DirIterator programs(directory.characters(), Core::DirIterator::SkipDots);
             while (programs.has_next()) {
                 auto program = programs.next_path();
-                auto program_path = DeprecatedString::formatted("{}/{}", directory, program);
+                auto program_path = ByteString::formatted("{}/{}", directory, program);
                 auto escaped_name = escape_token(program);
                 if (cached_path.contains_slow(escaped_name))
                     continue;
@@ -1577,7 +1577,7 @@ Vector<Line::CompletionSuggestion> Shell::complete(StringView line)
 Vector<Line::CompletionSuggestion> Shell::complete_path(StringView base, StringView part, size_t offset, ExecutableOnly executable_only, AST::Node const* command_node, AST::Node const* node, EscapeMode escape_mode)
 {
     auto token = offset ? part.substring_view(0, offset) : ""sv;
-    DeprecatedString path;
+    ByteString path;
 
     ssize_t last_slash = token.length() - 1;
     while (last_slash >= 0 && token[last_slash] != '/')
@@ -1615,7 +1615,7 @@ Vector<Line::CompletionSuggestion> Shell::complete_path(StringView base, StringV
         path_builder.append('/');
         path_builder.append(init_slash_part);
     }
-    path = path_builder.to_deprecated_string();
+    path = path_builder.to_byte_string();
     token = last_slash_part;
 
     // the invariant part of the token is actually just the last segment
@@ -1638,7 +1638,7 @@ Vector<Line::CompletionSuggestion> Shell::complete_path(StringView base, StringV
         auto file = files.next_path();
         if (file.starts_with(token)) {
             struct stat program_status;
-            auto file_path = DeprecatedString::formatted("{}/{}", path, file);
+            auto file_path = ByteString::formatted("{}/{}", path, file);
             int stat_error = stat(file_path.characters(), &program_status);
             if (!stat_error && (executable_only == ExecutableOnly::No || access(file_path.characters(), X_OK) == 0)) {
                 if (S_ISDIR(program_status.st_mode)) {
@@ -1678,7 +1678,7 @@ Vector<Line::CompletionSuggestion> Shell::complete_program_name(StringView name,
     if (!match)
         return complete_path(""sv, name, offset, ExecutableOnly::Yes, nullptr, nullptr, escape_mode);
 
-    DeprecatedString completion = match->path;
+    ByteString completion = match->path;
     auto token_length = escape_token(name, escape_mode).length();
     auto invariant_offset = token_length;
     size_t static_offset = 0;
@@ -1732,7 +1732,7 @@ Vector<Line::CompletionSuggestion> Shell::complete_variable(StringView name, siz
             auto parts = entry.split_view('=');
             if (parts.is_empty() || parts.first().is_empty())
                 continue;
-            DeprecatedString name = parts.first();
+            ByteString name = parts.first();
             if (suggestions.contains_slow(name))
                 continue;
             suggestions.append(move(name));
@@ -1764,7 +1764,7 @@ Vector<Line::CompletionSuggestion> Shell::complete_user(StringView name, size_t
         return suggestions;
 
     while (di.has_next()) {
-        DeprecatedString name = di.next_path();
+        ByteString name = di.next_path();
         if (name.starts_with(pattern)) {
             suggestions.append(name);
             auto& suggestion = suggestions.last();
@@ -2029,27 +2029,27 @@ ErrorOr<Vector<Line::CompletionSuggestion>> Shell::complete_via_program_itself(s
             auto parsed = parsed_result.release_value();
             if (parsed.is_object()) {
                 auto& object = parsed.as_object();
-                auto kind = object.get_deprecated_string("kind"sv).value_or("plain");
+                auto kind = object.get_byte_string("kind"sv).value_or("plain");
                 if (kind == "path") {
-                    auto base = object.get_deprecated_string("base"sv).value_or("");
-                    auto part = object.get_deprecated_string("part"sv).value_or("");
+                    auto base = object.get_byte_string("base"sv).value_or("");
+                    auto part = object.get_byte_string("part"sv).value_or("");
                     auto executable_only = object.get_bool("executable_only"sv).value_or(false) ? ExecutableOnly::Yes : ExecutableOnly::No;
                     suggestions.extend(complete_path(base, part, part.length(), executable_only, nullptr, nullptr));
                 } else if (kind == "program") {
-                    auto name = object.get_deprecated_string("name"sv).value_or("");
+                    auto name = object.get_byte_string("name"sv).value_or("");
                     suggestions.extend(complete_program_name(name, name.length()));
                 } else if (kind == "proxy") {
                     if (m_completion_stack_info.size_free() < 4 * KiB) {
                         dbgln("Not enough stack space, recursion?");
                         return IterationDecision::Continue;
                     }
-                    auto argv = object.get_deprecated_string("argv"sv).value_or("");
+                    auto argv = object.get_byte_string("argv"sv).value_or("");
                     dbgln("Proxy completion for {}", argv);
                     suggestions.extend(complete(argv));
                 } else if (kind == "plain") {
-                    auto completion_text = object.get_deprecated_string("completion"sv).value_or("");
-                    auto trailing_text = object.get_deprecated_string("trailing_trivia"sv).value_or("");
-                    auto display_text = object.get_deprecated_string("display_trivia"sv).value_or("");
+                    auto completion_text = object.get_byte_string("completion"sv).value_or("");
+                    auto trailing_text = object.get_byte_string("trailing_trivia"sv).value_or("");
+                    auto display_text = object.get_byte_string("display_trivia"sv).value_or("");
                     auto static_offset = object.get_u64("static_offset"sv).value_or(0);
                     auto invariant_offset = object.get_u64("invariant_offset"sv).value_or(0);
                     if (!object.get_bool("treat_as_code"sv).value_or(false)) {
@@ -2067,7 +2067,7 @@ ErrorOr<Vector<Line::CompletionSuggestion>> Shell::complete_via_program_itself(s
                     dbgln("LibLine: Unhandled completion kind: {}", kind);
                 }
             } else {
-                suggestions.append(parsed.to_deprecated_string());
+                suggestions.append(parsed.to_byte_string());
             }
 
             return IterationDecision::Continue;
@@ -2123,7 +2123,7 @@ void Shell::bring_cursor_to_beginning_of_a_line() const
     // Black with Cyan background.
     constexpr auto default_mark = "\e[30;46m%\e[0m";
     auto eol_mark_ptr = getenv("PROMPT_EOL_MARK");
-    DeprecatedString eol_mark = eol_mark_ptr ?: default_mark;
+    ByteString eol_mark = eol_mark_ptr ?: default_mark;
     size_t eol_mark_length = Line::Editor::actual_rendered_string_metrics(eol_mark).line_metrics.last().total_length();
     if (eol_mark_length >= ws.ws_col) {
         eol_mark = default_mark;
@@ -2135,7 +2135,7 @@ void Shell::bring_cursor_to_beginning_of_a_line() const
     // We write a line's worth of whitespace to the terminal. This way, we ensure that
     // the prompt ends up on a new line even if there is dangling output on the current line.
     size_t fill_count = ws.ws_col - eol_mark_length;
-    auto fill_buffer = DeprecatedString::repeated(' ', fill_count);
+    auto fill_buffer = ByteString::repeated(' ', fill_count);
     fwrite(fill_buffer.characters(), 1, fill_count, stderr);
 
     putc('\r', stderr);
@@ -2351,7 +2351,7 @@ Shell::Shell()
         if (path.length())
             path.append(":"sv);
         path.append(DEFAULT_PATH_SV);
-        setenv("PATH", path.to_deprecated_string().characters(), true);
+        setenv("PATH", path.to_byte_string().characters(), true);
     }
 
     cache_path();
diff --git a/Userland/Shell/Shell.h b/Userland/Shell/Shell.h
index d38e210db56..9bf9e68e53a 100644
--- a/Userland/Shell/Shell.h
+++ b/Userland/Shell/Shell.h
@@ -9,8 +9,8 @@
 #include "Job.h"
 #include "Parser.h"
 #include <AK/Array.h>
+#include <AK/ByteString.h>
 #include <AK/CircularQueue.h>
-#include <AK/DeprecatedString.h>
 #include <AK/HashMap.h>
 #include <AK/IntrusiveList.h>
 #include <AK/StackInfo.h>
@@ -119,8 +119,8 @@ public:
     void setup_keybinds();
 
     struct SourcePosition {
-        Optional<DeprecatedString> source_file;
-        DeprecatedString literal_source_text;
+        Optional<ByteString> source_file;
+        ByteString literal_source_text;
         Optional<AST::Position> position;
     };
 
@@ -133,7 +133,7 @@ public:
         };
 
         Kind kind;
-        DeprecatedString path;
+        ByteString path;
 
         bool operator<(RunnablePath const& other) const
         {
@@ -169,38 +169,38 @@ public:
 
     int run_command(StringView, Optional<SourcePosition> = {});
     Optional<RunnablePath> runnable_path_for(StringView);
-    Optional<DeprecatedString> help_path_for(Vector<RunnablePath> visited, RunnablePath const& runnable_path);
+    Optional<ByteString> help_path_for(Vector<RunnablePath> visited, RunnablePath const& runnable_path);
     ErrorOr<RefPtr<Job>> run_command(const AST::Command&);
     Vector<NonnullRefPtr<Job>> run_commands(Vector<AST::Command>&);
-    bool run_file(DeprecatedString const&, bool explicitly_invoked = true);
+    bool run_file(ByteString const&, bool explicitly_invoked = true);
     ErrorOr<bool> run_builtin(const AST::Command&, Vector<NonnullRefPtr<AST::Rewiring>> const&, int& retval);
     bool has_builtin(StringView) const;
     ErrorOr<RefPtr<AST::Node>> run_immediate_function(StringView name, AST::ImmediateExpression& invoking_node, Vector<NonnullRefPtr<AST::Node>> const&);
     static bool has_immediate_function(StringView);
     void block_on_job(RefPtr<Job>);
     void block_on_pipeline(RefPtr<AST::Pipeline>);
-    DeprecatedString prompt() const;
+    ByteString prompt() const;
 
-    static DeprecatedString expand_tilde(StringView expression);
-    static ErrorOr<Vector<DeprecatedString>> expand_globs(StringView path, StringView base);
-    static Vector<DeprecatedString> expand_globs(Vector<StringView> path_segments, StringView base);
+    static ByteString expand_tilde(StringView expression);
+    static ErrorOr<Vector<ByteString>> expand_globs(StringView path, StringView base);
+    static Vector<ByteString> expand_globs(Vector<StringView> path_segments, StringView base);
     ErrorOr<Vector<AST::Command>> expand_aliases(Vector<AST::Command>);
-    DeprecatedString resolve_path(DeprecatedString) const;
-    Optional<DeprecatedString> resolve_alias(StringView) const;
+    ByteString resolve_path(ByteString) const;
+    Optional<ByteString> resolve_alias(StringView) const;
 
     static bool has_history_event(StringView);
 
     ErrorOr<RefPtr<AST::Value const>> get_argument(size_t) const;
     ErrorOr<RefPtr<AST::Value const>> look_up_local_variable(StringView) const;
-    ErrorOr<DeprecatedString> local_variable_or(StringView, DeprecatedString const&) const;
-    void set_local_variable(DeprecatedString const&, RefPtr<AST::Value>, bool only_in_current_frame = false);
+    ErrorOr<ByteString> local_variable_or(StringView, ByteString const&) const;
+    void set_local_variable(ByteString const&, RefPtr<AST::Value>, bool only_in_current_frame = false);
     void unset_local_variable(StringView, bool only_in_current_frame = false);
 
-    void define_function(DeprecatedString name, Vector<DeprecatedString> argnames, RefPtr<AST::Node> body);
+    void define_function(ByteString name, Vector<ByteString> argnames, RefPtr<AST::Node> body);
     bool has_function(StringView);
     bool invoke_function(const AST::Command&, int& retval);
 
-    DeprecatedString format(StringView, ssize_t& cursor) const;
+    ByteString format(StringView, ssize_t& cursor) const;
 
     RefPtr<Line::Editor> editor() const { return m_editor; }
 
@@ -209,15 +209,15 @@ public:
         Block,
     };
     struct LocalFrame {
-        LocalFrame(DeprecatedString name, HashMap<DeprecatedString, RefPtr<AST::Value>> variables, LocalFrameKind kind = LocalFrameKind::Block)
+        LocalFrame(ByteString name, HashMap<ByteString, RefPtr<AST::Value>> variables, LocalFrameKind kind = LocalFrameKind::Block)
             : name(move(name))
             , local_variables(move(variables))
             , is_function_frame(kind == LocalFrameKind::FunctionOrGlobal)
         {
         }
 
-        DeprecatedString name;
-        HashMap<DeprecatedString, RefPtr<AST::Value>> local_variables;
+        ByteString name;
+        HashMap<ByteString, RefPtr<AST::Value>> local_variables;
         bool is_function_frame;
     };
 
@@ -237,16 +237,16 @@ public:
         bool should_destroy_frame { true };
     };
 
-    [[nodiscard]] Frame push_frame(DeprecatedString name, LocalFrameKind = LocalFrameKind::Block);
+    [[nodiscard]] Frame push_frame(ByteString name, LocalFrameKind = LocalFrameKind::Block);
     void pop_frame();
 
     struct Promise {
         struct Data {
             struct Unveil {
-                DeprecatedString path;
-                DeprecatedString access;
+                ByteString path;
+                ByteString access;
             };
-            DeprecatedString exec_promises;
+            ByteString exec_promises;
             Vector<Unveil> unveils;
         } data;
 
@@ -280,11 +280,11 @@ public:
         SingleQuotedString,
         DoubleQuotedString,
     };
-    static DeprecatedString escape_token_for_double_quotes(StringView token);
-    static DeprecatedString escape_token_for_single_quotes(StringView token);
-    static DeprecatedString escape_token(StringView token, EscapeMode = EscapeMode::Bareword);
-    static DeprecatedString escape_token(Utf32View token, EscapeMode = EscapeMode::Bareword);
-    static DeprecatedString unescape_token(StringView token);
+    static ByteString escape_token_for_double_quotes(StringView token);
+    static ByteString escape_token_for_single_quotes(StringView token);
+    static ByteString escape_token(StringView token, EscapeMode = EscapeMode::Bareword);
+    static ByteString escape_token(Utf32View token, EscapeMode = EscapeMode::Bareword);
+    static ByteString unescape_token(StringView token);
     enum class SpecialCharacterEscapeMode {
         Untouched,
         Escaped,
@@ -319,7 +319,7 @@ public:
     Job* current_job() const { return m_current_job; }
     void kill_job(Job const*, int sig);
 
-    DeprecatedString get_history_path();
+    ByteString get_history_path();
     void print_path(StringView path);
     void cache_path();
 
@@ -334,9 +334,9 @@ public:
     bool was_interrupted { false };
     bool was_resized { false };
 
-    DeprecatedString cwd;
-    DeprecatedString username;
-    DeprecatedString home;
+    ByteString cwd;
+    ByteString username;
+    ByteString home;
 
     constexpr static auto TTYNameSize = 32;
     constexpr static auto HostNameSize = 64;
@@ -346,12 +346,12 @@ public:
 
     uid_t uid;
     Optional<int> last_return_code;
-    Vector<DeprecatedString> directory_stack;
-    CircularQueue<DeprecatedString, 8> cd_history; // FIXME: have a configurable cd history length
+    Vector<ByteString> directory_stack;
+    CircularQueue<ByteString, 8> cd_history; // FIXME: have a configurable cd history length
     HashMap<u64, NonnullRefPtr<Job>> jobs;
     Vector<RunnablePath, 256> cached_path;
 
-    DeprecatedString current_script;
+    ByteString current_script;
 
     enum ShellEventType {
         ReadLine,
@@ -375,7 +375,7 @@ public:
         WriteFailure,
     };
 
-    void raise_error(ShellError kind, DeprecatedString description, Optional<AST::Position> position = {})
+    void raise_error(ShellError kind, ByteString description, Optional<AST::Position> position = {})
     {
         m_error = kind;
         m_error_description = move(description);
@@ -384,7 +384,7 @@ public:
     }
     bool has_error(ShellError err) const { return m_error == err; }
     bool has_any_error() const { return !has_error(ShellError::None); }
-    DeprecatedString const& error_description() const { return m_error_description; }
+    ByteString const& error_description() const { return m_error_description; }
     ShellError take_error()
     {
         auto err = m_error;
@@ -484,8 +484,8 @@ private:
     };
 
     struct ShellFunction {
-        DeprecatedString name;
-        Vector<DeprecatedString> arguments;
+        ByteString name;
+        Vector<ByteString> arguments;
         RefPtr<AST::Node> body;
     };
 
@@ -494,19 +494,19 @@ private:
     bool m_should_ignore_jobs_on_next_exit { false };
     pid_t m_pid { 0 };
 
-    HashMap<DeprecatedString, ShellFunction> m_functions;
+    HashMap<ByteString, ShellFunction> m_functions;
     Vector<NonnullOwnPtr<LocalFrame>> m_local_frames;
     Promise::List m_active_promises;
     Vector<NonnullRefPtr<AST::Redirection>> m_global_redirections;
 
-    HashMap<DeprecatedString, DeprecatedString> m_aliases;
+    HashMap<ByteString, ByteString> m_aliases;
     bool m_is_interactive { true };
     bool m_is_subshell { false };
     bool m_should_reinstall_signal_handlers { true };
     bool m_in_posix_mode { false };
 
     ShellError m_error { ShellError::None };
-    DeprecatedString m_error_description;
+    ByteString m_error_description;
     Optional<SourcePosition> m_source_position;
 
     bool m_should_format_live { false };
@@ -522,7 +522,7 @@ private:
     StackInfo m_completion_stack_info;
 
     RefPtr<AST::Node> m_prompt_command_node;
-    mutable Optional<DeprecatedString> m_next_scheduled_prompt_text;
+    mutable Optional<ByteString> m_next_scheduled_prompt_text;
 };
 
 [[maybe_unused]] static constexpr bool is_word_character(char c)
@@ -606,7 +606,7 @@ struct Traits<Shell::Shell::RunnablePath> : public DefaultTraits<Shell::Shell::R
         return self.path == other;
     }
 
-    static bool equals(Shell::Shell::RunnablePath const& self, DeprecatedString const& other)
+    static bool equals(Shell::Shell::RunnablePath const& self, ByteString const& other)
     {
         return self.path == other;
     }
diff --git a/Userland/Shell/main.cpp b/Userland/Shell/main.cpp
index 6b0355164db..371f4689996 100644
--- a/Userland/Shell/main.cpp
+++ b/Userland/Shell/main.cpp
@@ -113,7 +113,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             }
 
             if (should_escape) {
-                DeprecatedString escaped_string;
+                ByteString escaped_string;
                 Optional<char> trivia {};
                 bool starting_trivia_already_provided = false;
                 auto escape_mode = Shell::Shell::EscapeMode::Bareword;
@@ -227,7 +227,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     if (!skip_rc_files) {
         auto run_rc_file = [&](auto& name) {
-            DeprecatedString file_path = name;
+            ByteString file_path = name;
             if (file_path.starts_with('~'))
                 file_path = shell->expand_tilde(file_path);
             if (FileSystem::exists(file_path)) {
diff --git a/Userland/Utilities/arp.cpp b/Userland/Utilities/arp.cpp
index 9c4684f5aba..6dc3be950f8 100644
--- a/Userland/Utilities/arp.cpp
+++ b/Userland/Utilities/arp.cpp
@@ -97,13 +97,13 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         Vector<JsonValue> sorted_regions = json.as_array().values();
         quick_sort(sorted_regions, [](auto& a, auto& b) {
-            return a.as_object().get_deprecated_string("ip_address"sv).value_or({}) < b.as_object().get_deprecated_string("ip_address"sv).value_or({});
+            return a.as_object().get_byte_string("ip_address"sv).value_or({}) < b.as_object().get_byte_string("ip_address"sv).value_or({});
         });
 
         for (auto& value : sorted_regions) {
             auto& if_object = value.as_object();
 
-            auto ip_address = if_object.get_deprecated_string("ip_address"sv).value_or({});
+            auto ip_address = if_object.get_byte_string("ip_address"sv).value_or({});
 
             if (!flag_numeric) {
                 auto from_string = IPv4Address::from_string(ip_address);
@@ -116,7 +116,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 }
             }
 
-            auto mac_address = if_object.get_deprecated_string("mac_address"sv).value_or({});
+            auto mac_address = if_object.get_byte_string("mac_address"sv).value_or({});
 
             if (proto_address_column != -1)
                 columns[proto_address_column].buffer = ip_address;
diff --git a/Userland/Utilities/bt.cpp b/Userland/Utilities/bt.cpp
index 543feea17ec..b81f87b4800 100644
--- a/Userland/Utilities/bt.cpp
+++ b/Userland/Utilities/bt.cpp
@@ -26,7 +26,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.parse(arguments);
     Core::EventLoop loop;
 
-    Core::DirIterator iterator(DeprecatedString::formatted("/proc/{}/stacks", pid), Core::DirIterator::SkipDots);
+    Core::DirIterator iterator(ByteString::formatted("/proc/{}/stacks", pid), Core::DirIterator::SkipDots);
     if (iterator.has_error()) {
         warnln("Error: pid '{}' doesn't appear to exist.", pid);
         return 1;
@@ -54,7 +54,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
                     // See if we can find the sources in /usr/src
                     // FIXME: I'm sure this can be improved!
-                    auto full_path = LexicalPath::canonicalized_path(DeprecatedString::formatted("/usr/src/serenity/dummy/dummy/{}", source_position.file_path));
+                    auto full_path = LexicalPath::canonicalized_path(ByteString::formatted("/usr/src/serenity/dummy/dummy/{}", source_position.file_path));
                     if (access(full_path.characters(), F_OK) == 0) {
                         linked = true;
                         auto url = URL::create_with_file_scheme(full_path, {}, hostname);
diff --git a/Userland/Utilities/cal.cpp b/Userland/Utilities/cal.cpp
index da29485ae38..f06265f0452 100644
--- a/Userland/Utilities/cal.cpp
+++ b/Userland/Utilities/cal.cpp
@@ -51,7 +51,7 @@ static ErrorOr<int> weekday_index(StringView weekday_name)
 static ErrorOr<int> default_weekday_start()
 {
     auto calendar_config = TRY(Core::ConfigFile::open_for_app("Calendar"sv));
-    String default_first_day_of_week = TRY(String::from_deprecated_string(calendar_config->read_entry("View"sv, "FirstDayOfWeek"sv, "Sunday"sv)));
+    String default_first_day_of_week = TRY(String::from_byte_string(calendar_config->read_entry("View"sv, "FirstDayOfWeek"sv, "Sunday"sv)));
     return TRY(weekday_index(default_first_day_of_week));
 }
 
diff --git a/Userland/Utilities/checksum.cpp b/Userland/Utilities/checksum.cpp
index 3a497ef3a0b..be9e0f61cc9 100644
--- a/Userland/Utilities/checksum.cpp
+++ b/Userland/Utilities/checksum.cpp
@@ -35,8 +35,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         exit(1);
     }
 
-    auto hash_name = program_name.substring_view(0, program_name.length() - 3).to_deprecated_string().to_uppercase();
-    auto paths_help_string = DeprecatedString::formatted("File(s) to print {} checksum of", hash_name);
+    auto hash_name = program_name.substring_view(0, program_name.length() - 3).to_byte_string().to_uppercase();
+    auto paths_help_string = ByteString::formatted("File(s) to print {} checksum of", hash_name);
 
     bool verify_from_paths = false;
     Vector<StringView> paths;
@@ -99,7 +99,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 hash.reset();
                 while (!file_from_filename->is_eof())
                     hash.update(TRY(file_from_filename->read_some(buffer)));
-                if (DeprecatedString::formatted("{:hex-dump}", hash.digest().bytes()) == line[0])
+                if (ByteString::formatted("{:hex-dump}", hash.digest().bytes()) == line[0])
                     outln("{}: OK", filename);
                 else {
                     ++failed_verification_count;
diff --git a/Userland/Utilities/comm.cpp b/Userland/Utilities/comm.cpp
index 8ca230a3a58..97e897c7c2e 100644
--- a/Userland/Utilities/comm.cpp
+++ b/Userland/Utilities/comm.cpp
@@ -22,8 +22,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio rpath"));
 
-    DeprecatedString file1_path;
-    DeprecatedString file2_path;
+    ByteString file1_path;
+    ByteString file2_path;
     bool suppress_col1 { false };
     bool suppress_col2 { false };
     bool suppress_col3 { false };
@@ -61,7 +61,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return 1;
     }
 
-    auto open_file = [](DeprecatedString const& path, auto& file, int file_number) {
+    auto open_file = [](ByteString const& path, auto& file, int file_number) {
         auto file_or_error = Core::File::open_file_or_standard_stream(path, Core::File::OpenMode::Read);
         if (file_or_error.is_error()) {
             warnln("Failed to open file{} '{}': {}", file_number, path, file_or_error.error());
@@ -90,17 +90,17 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     char tab { '\t' };
     size_t tab_count { 0 };
-    DeprecatedString col1_fmt;
-    DeprecatedString col2_fmt;
-    DeprecatedString col3_fmt;
+    ByteString col1_fmt;
+    ByteString col2_fmt;
+    ByteString col3_fmt;
     if (!suppress_col1)
-        col1_fmt = DeprecatedString::formatted("{}{}", DeprecatedString::repeated(tab, tab_count++), print_color ? COL1_COLOR : "{}");
+        col1_fmt = ByteString::formatted("{}{}", ByteString::repeated(tab, tab_count++), print_color ? COL1_COLOR : "{}");
     if (!suppress_col2)
-        col2_fmt = DeprecatedString::formatted("{}{}", DeprecatedString::repeated(tab, tab_count++), print_color ? COL2_COLOR : "{}");
+        col2_fmt = ByteString::formatted("{}{}", ByteString::repeated(tab, tab_count++), print_color ? COL2_COLOR : "{}");
     if (!suppress_col3)
-        col3_fmt = DeprecatedString::formatted("{}{}", DeprecatedString::repeated(tab, tab_count++), print_color ? COL3_COLOR : "{}");
+        col3_fmt = ByteString::formatted("{}{}", ByteString::repeated(tab, tab_count++), print_color ? COL3_COLOR : "{}");
 
-    auto cmp = [&](DeprecatedString const& str1, DeprecatedString const& str2) {
+    auto cmp = [&](ByteString const& str1, ByteString const& str2) {
         if (case_insensitive)
             return strcasecmp(str1.characters(), str2.characters());
         return strcmp(str1.characters(), str2.characters());
@@ -111,8 +111,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     int col1_count { 0 };
     int col2_count { 0 };
     int col3_count { 0 };
-    DeprecatedString file1_line;
-    DeprecatedString file2_line;
+    ByteString file1_line;
+    ByteString file2_line;
     Array<u8, PAGE_SIZE> buffer;
 
     auto should_continue_comparing_files = [&]() {
@@ -167,7 +167,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         outln(col2_fmt, file2_line);
     }
 
-    auto process_remaining = [&](DeprecatedString const& fmt, auto& file, int& count, bool print) {
+    auto process_remaining = [&](ByteString const& fmt, auto& file, int& count, bool print) {
         while (true) {
             auto can_read_result = file->can_read_line();
             if (can_read_result.is_error() || !can_read_result.value())
diff --git a/Userland/Utilities/cp.cpp b/Userland/Utilities/cp.cpp
index 5cef5959c97..643e40a5ee1 100644
--- a/Userland/Utilities/cp.cpp
+++ b/Userland/Utilities/cp.cpp
@@ -21,7 +21,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     bool recursion_allowed = false;
     bool verbose = false;
     Vector<StringView> sources;
-    DeprecatedString destination;
+    ByteString destination;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(link, "Link files instead of copying", "link", 'l');
@@ -73,7 +73,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     for (auto& source : sources) {
         auto destination_path = destination_is_existing_dir
-            ? DeprecatedString::formatted("{}/{}", destination, LexicalPath::basename(source))
+            ? ByteString::formatted("{}/{}", destination, LexicalPath::basename(source))
             : destination;
 
         auto result = FileSystem::copy_file_or_directory(
diff --git a/Userland/Utilities/cpp-lexer.cpp b/Userland/Utilities/cpp-lexer.cpp
index eda344cd7d1..888e30aaff5 100644
--- a/Userland/Utilities/cpp-lexer.cpp
+++ b/Userland/Utilities/cpp-lexer.cpp
@@ -23,7 +23,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     Cpp::Lexer lexer(content);
     lexer.lex_iterable([](auto token) {
-        outln("{}", token.to_deprecated_string());
+        outln("{}", token.to_byte_string());
     });
 
     return 0;
diff --git a/Userland/Utilities/cpp-preprocessor.cpp b/Userland/Utilities/cpp-preprocessor.cpp
index 3efbf4f920b..36a2a5de4e3 100644
--- a/Userland/Utilities/cpp-preprocessor.cpp
+++ b/Userland/Utilities/cpp-preprocessor.cpp
@@ -21,7 +21,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto file = TRY(Core::File::open(path, Core::File::OpenMode::Read));
     auto content = TRY(file->read_until_eof());
-    DeprecatedString name = LexicalPath::basename(path);
+    ByteString name = LexicalPath::basename(path);
     Cpp::Preprocessor cpp(name, StringView { content });
     auto tokens = cpp.process_and_lex();
 
@@ -31,13 +31,13 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             if (definition.value.parameters.is_empty())
                 outln("{}: {}", definition.key, definition.value.value);
             else
-                outln("{}({}): {}", definition.key, DeprecatedString::join(',', definition.value.parameters), definition.value.value);
+                outln("{}({}): {}", definition.key, ByteString::join(',', definition.value.parameters), definition.value.value);
         }
         outln("");
     }
 
     for (auto& token : tokens) {
-        outln("{}", token.to_deprecated_string());
+        outln("{}", token.to_byte_string());
     }
 
     return 0;
diff --git a/Userland/Utilities/cut.cpp b/Userland/Utilities/cut.cpp
index c6824ea0318..ad4eee36d38 100644
--- a/Userland/Utilities/cut.cpp
+++ b/Userland/Utilities/cut.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/QuickSort.h>
 #include <AK/StdLibExtras.h>
 #include <AK/Vector.h>
@@ -33,9 +33,9 @@ struct Range {
     }
 };
 
-static bool expand_list(DeprecatedString& list, Vector<Range>& ranges)
+static bool expand_list(ByteString& list, Vector<Range>& ranges)
 {
-    Vector<DeprecatedString> tokens = list.split(',', SplitBehavior::KeepEmpty);
+    Vector<ByteString> tokens = list.split(',', SplitBehavior::KeepEmpty);
 
     for (auto& token : tokens) {
         if (token.length() == 0) {
@@ -128,7 +128,7 @@ static void process_line_bytes(StringView line, Vector<Range> const& ranges)
             continue;
 
         auto to = min(i.m_to, line.length());
-        auto sub_string = DeprecatedString(line).substring(i.m_from - 1, to - i.m_from + 1);
+        auto sub_string = ByteString(line).substring(i.m_from - 1, to - i.m_from + 1);
         out("{}", sub_string);
     }
     outln();
@@ -136,7 +136,7 @@ static void process_line_bytes(StringView line, Vector<Range> const& ranges)
 
 static void process_line_fields(StringView line, Vector<Range> const& ranges, char delimiter, bool only_print_delimited_lines)
 {
-    auto string_split = DeprecatedString(line).split(delimiter, SplitBehavior::KeepEmpty);
+    auto string_split = ByteString(line).split(delimiter, SplitBehavior::KeepEmpty);
     if (string_split.size() == 1) {
         if (!only_print_delimited_lines)
             outln("{}", line);
@@ -144,21 +144,21 @@ static void process_line_fields(StringView line, Vector<Range> const& ranges, ch
         return;
     }
 
-    Vector<DeprecatedString> output_fields;
+    Vector<ByteString> output_fields;
     for (auto& range : ranges) {
         for (size_t i = range.m_from - 1; i < min(range.m_to, string_split.size()); i++) {
             output_fields.append(string_split[i]);
         }
     }
 
-    outln("{}", DeprecatedString::join(delimiter, output_fields));
+    outln("{}", ByteString::join(delimiter, output_fields));
 }
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
-    DeprecatedString byte_list = "";
-    DeprecatedString fields_list = "";
-    DeprecatedString delimiter = "\t";
+    ByteString byte_list = "";
+    ByteString fields_list = "";
+    ByteString delimiter = "\t";
     bool only_print_delimited_lines = false;
 
     Vector<StringView> files;
@@ -194,7 +194,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return 1;
     }
 
-    DeprecatedString ranges_list;
+    ByteString ranges_list;
     Vector<Range> ranges_vector;
 
     if (selected_bytes) {
diff --git a/Userland/Utilities/date.cpp b/Userland/Utilities/date.cpp
index ab876f2aa18..8b487973648 100644
--- a/Userland/Utilities/date.cpp
+++ b/Userland/Utilities/date.cpp
@@ -57,17 +57,17 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             warnln("date: Format string must start with '+'");
             return 1;
         }
-        outln("{}", date.to_deprecated_string(format_string.substring_view(1)));
+        outln("{}", date.to_byte_string(format_string.substring_view(1)));
     } else if (print_unix_date) {
         outln("{}", date.timestamp());
     } else if (print_iso_8601) {
-        outln("{}", date.to_deprecated_string("%Y-%m-%dT%H:%M:%S%:z"sv));
+        outln("{}", date.to_byte_string("%Y-%m-%dT%H:%M:%S%:z"sv));
     } else if (print_rfc_5322) {
-        outln("{}", date.to_deprecated_string("%a, %d %b %Y %H:%M:%S %z"sv));
+        outln("{}", date.to_byte_string("%a, %d %b %Y %H:%M:%S %z"sv));
     } else if (print_rfc_3339) {
-        outln("{}", date.to_deprecated_string("%Y-%m-%d %H:%M:%S%:z"sv));
+        outln("{}", date.to_byte_string("%Y-%m-%d %H:%M:%S%:z"sv));
     } else {
-        outln("{}", date.to_deprecated_string("%Y-%m-%d %H:%M:%S %Z"sv));
+        outln("{}", date.to_byte_string("%Y-%m-%d %H:%M:%S %Z"sv));
     }
     return 0;
 }
diff --git a/Userland/Utilities/dd.cpp b/Userland/Utilities/dd.cpp
index 01481db66ed..a0d9c3ce20b 100644
--- a/Userland/Utilities/dd.cpp
+++ b/Userland/Utilities/dd.cpp
@@ -5,8 +5,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/NumberFormat.h>
 #include <AK/Optional.h>
 #include <AK/Vector.h>
@@ -56,7 +56,7 @@ static void closing_statistics()
     warnln("{}+{} blocks out", statistics.total_blocks_out, statistics.partial_blocks_out);
     if (statistics.status != Noxfer) {
         auto elapsed_time = statistics.timer.elapsed_time();
-        DeprecatedString copy_speed = "INF B/s";
+        ByteString copy_speed = "INF B/s";
         if (!elapsed_time.is_zero()) {
             auto speed = statistics.total_bytes_copied * 1000 / elapsed_time.to_milliseconds();
             copy_speed = human_readable_quantity(speed, AK::HumanReadableBasedOn::Base2, "B/s"sv);
@@ -83,7 +83,7 @@ static int handle_io_file_arguments(int& fd, int flags, StringView argument)
         return -1;
     }
 
-    fd = open(value.to_deprecated_string().characters(), flags, 0666);
+    fd = open(value.to_byte_string().characters(), flags, 0666);
     if (fd == -1) {
         warnln("Unable to open: {}", value);
         return -1;
diff --git a/Userland/Utilities/df.cpp b/Userland/Utilities/df.cpp
index 2d5a95d375b..819974374ae 100644
--- a/Userland/Utilities/df.cpp
+++ b/Userland/Utilities/df.cpp
@@ -14,13 +14,13 @@
 #include <stdlib.h>
 
 struct FileSystem {
-    DeprecatedString fs;
+    ByteString fs;
     size_t total_block_count { 0 };
     size_t free_block_count { 0 };
     size_t total_inode_count { 0 };
     size_t free_inode_count { 0 };
     size_t block_size { 0 };
-    DeprecatedString mount_point;
+    ByteString mount_point;
 };
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
@@ -62,7 +62,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto const& json = json_result.as_array();
     json.for_each([&](auto& value) {
         auto& fs_object = value.as_object();
-        auto fs = fs_object.get_deprecated_string("class_name"sv).value_or({});
+        auto fs = fs_object.get_byte_string("class_name"sv).value_or({});
         auto total_block_count = fs_object.get_u64("total_block_count"sv).value_or(0);
         auto free_block_count = fs_object.get_u64("free_block_count"sv).value_or(0);
         auto used_block_count = total_block_count - free_block_count;
@@ -70,7 +70,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         auto free_inode_count = fs_object.get_u64("free_inode_count"sv).value_or(0);
         auto used_inode_count = total_inode_count - free_inode_count;
         auto block_size = fs_object.get_u64("block_size"sv).value_or(0);
-        auto mount_point = fs_object.get_deprecated_string("mount_point"sv).value_or({});
+        auto mount_point = fs_object.get_byte_string("mount_point"sv).value_or({});
 
         auto used_percentage = 100;
         if (total_block_count != 0)
diff --git a/Userland/Utilities/dirname.cpp b/Userland/Utilities/dirname.cpp
index 7d3b7c903d8..41b6f4a4a51 100644
--- a/Userland/Utilities/dirname.cpp
+++ b/Userland/Utilities/dirname.cpp
@@ -12,7 +12,7 @@
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     bool null_terminated = false;
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
     Core::ArgsParser args_parser;
     args_parser.add_option(null_terminated, "End each output line with \\0, rather than \\n", "zero", 'z');
     args_parser.add_positional_argument(paths, "Path", "path");
diff --git a/Userland/Utilities/disasm.cpp b/Userland/Utilities/disasm.cpp
index 0703c81a80c..4892e988534 100644
--- a/Userland/Utilities/disasm.cpp
+++ b/Userland/Utilities/disasm.cpp
@@ -141,7 +141,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
                 builder.append("   "sv);
         }
         builder.append(" "sv);
-        builder.append(insn.value().to_deprecated_string(virtual_offset, symbol_provider));
+        builder.append(insn.value().to_byte_string(virtual_offset, symbol_provider));
         outln("{}", builder.string_view());
 
         for (size_t bytes_printed = 7; bytes_printed < length; bytes_printed += 7) {
diff --git a/Userland/Utilities/disk_benchmark.cpp b/Userland/Utilities/disk_benchmark.cpp
index e65ceac5e09..1339cc8be71 100644
--- a/Userland/Utilities/disk_benchmark.cpp
+++ b/Userland/Utilities/disk_benchmark.cpp
@@ -6,7 +6,7 @@
  */
 
 #include <AK/ByteBuffer.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/ScopeGuard.h>
 #include <AK/Types.h>
 #include <AK/Vector.h>
@@ -39,13 +39,13 @@ static Result average_result(Vector<Result> const& results)
     return average;
 }
 
-static ErrorOr<Result> benchmark(DeprecatedString const& filename, int file_size, ByteBuffer& buffer, bool allow_cache);
+static ErrorOr<Result> benchmark(ByteString const& filename, int file_size, ByteBuffer& buffer, bool allow_cache);
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     using namespace AK::TimeLiterals;
 
-    DeprecatedString directory = ".";
+    ByteString directory = ".";
     i64 time_per_benchmark_sec = 10;
     Vector<size_t> file_sizes;
     Vector<size_t> block_sizes;
@@ -68,7 +68,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         block_sizes = { 8192, 32768, 65536 };
     }
 
-    auto filename = DeprecatedString::formatted("{}/disk_benchmark.tmp", directory);
+    auto filename = ByteString::formatted("{}/disk_benchmark.tmp", directory);
 
     for (auto file_size : file_sizes) {
         for (auto block_size : block_sizes) {
@@ -101,7 +101,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     return 0;
 }
 
-ErrorOr<Result> benchmark(DeprecatedString const& filename, int file_size, ByteBuffer& buffer, bool allow_cache)
+ErrorOr<Result> benchmark(ByteString const& filename, int file_size, ByteBuffer& buffer, bool allow_cache)
 {
     int flags = O_CREAT | O_TRUNC | O_RDWR;
     if (!allow_cache)
diff --git a/Userland/Utilities/du.cpp b/Userland/Utilities/du.cpp
index 6415a3d80aa..9cd5c2faa8b 100644
--- a/Userland/Utilities/du.cpp
+++ b/Userland/Utilities/du.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/NumberFormat.h>
 #include <AK/Vector.h>
@@ -32,7 +32,7 @@ struct DuOption {
     bool one_file_system = false;
     i64 threshold = 0;
     TimeType time_type = TimeType::NotUsed;
-    Vector<DeprecatedString> excluded_patterns;
+    Vector<ByteString> excluded_patterns;
     u64 block_size = 1024;
     size_t max_depth = SIZE_MAX;
 };
@@ -57,12 +57,12 @@ struct AK::Traits<VisitedFile> : public DefaultTraits<VisitedFile> {
 
 static HashTable<VisitedFile> s_visited_files;
 
-static ErrorOr<void> parse_args(Main::Arguments arguments, Vector<DeprecatedString>& files, DuOption& du_option);
-static u64 print_space_usage(DeprecatedString const& path, DuOption const& du_option, size_t current_depth, Optional<dev_t> root_device = {});
+static ErrorOr<void> parse_args(Main::Arguments arguments, Vector<ByteString>& files, DuOption& du_option);
+static u64 print_space_usage(ByteString const& path, DuOption const& du_option, size_t current_depth, Optional<dev_t> root_device = {});
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
-    Vector<DeprecatedString> files;
+    Vector<ByteString> files;
     DuOption du_option;
 
     TRY(parse_args(arguments, files, du_option));
@@ -73,7 +73,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     return 0;
 }
 
-ErrorOr<void> parse_args(Main::Arguments arguments, Vector<DeprecatedString>& files, DuOption& du_option)
+ErrorOr<void> parse_args(Main::Arguments arguments, Vector<ByteString>& files, DuOption& du_option)
 {
     bool summarize = false;
     StringView pattern;
@@ -140,7 +140,7 @@ ErrorOr<void> parse_args(Main::Arguments arguments, Vector<DeprecatedString>& fi
         auto file = TRY(Core::File::open(exclude_from, Core::File::OpenMode::Read));
         auto const buff = TRY(file->read_until_eof());
         if (!buff.is_empty()) {
-            DeprecatedString patterns = DeprecatedString::copy(buff, Chomp);
+            ByteString patterns = ByteString::copy(buff, Chomp);
             du_option.excluded_patterns.extend(patterns.split('\n'));
         }
     }
@@ -156,7 +156,7 @@ ErrorOr<void> parse_args(Main::Arguments arguments, Vector<DeprecatedString>& fi
     return {};
 }
 
-u64 print_space_usage(DeprecatedString const& path, DuOption const& du_option, size_t current_depth, Optional<dev_t> root_device)
+u64 print_space_usage(ByteString const& path, DuOption const& du_option, size_t current_depth, Optional<dev_t> root_device)
 {
     u64 size = 0;
     auto path_stat_or_error = Core::System::lstat(path);
@@ -240,7 +240,7 @@ u64 print_space_usage(DeprecatedString const& path, DuOption const& du_option, s
             break;
         }
 
-        auto const formatted_time = Core::DateTime::from_timestamp(time).to_deprecated_string();
+        auto const formatted_time = Core::DateTime::from_timestamp(time).to_byte_string();
         outln("\t{}\t{}", formatted_time, path);
     }
 
diff --git a/Userland/Utilities/echo.cpp b/Userland/Utilities/echo.cpp
index 5eb71c9f295..d5c7296c621 100644
--- a/Userland/Utilities/echo.cpp
+++ b/Userland/Utilities/echo.cpp
@@ -39,7 +39,7 @@ static Optional<u8> parse_hex_number(GenericLexer& lexer)
     return value;
 }
 
-static DeprecatedString interpret_backslash_escapes(StringView string, bool& no_trailing_newline)
+static ByteString interpret_backslash_escapes(StringView string, bool& no_trailing_newline)
 {
     static constexpr auto escape_map = "a\ab\be\ef\fn\nr\rt\tv\v"sv;
     static constexpr auto unescaped_chars = "\a\b\e\f\n\r\t\v\\"sv;
@@ -94,14 +94,14 @@ static DeprecatedString interpret_backslash_escapes(StringView string, bool& no_
         }
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio"));
 
-    Vector<DeprecatedString> text;
+    Vector<ByteString> text;
     bool no_trailing_newline = false;
     bool should_interpret_backslash_escapes = false;
 
@@ -118,7 +118,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return 0;
     }
 
-    auto output = DeprecatedString::join(' ', text);
+    auto output = ByteString::join(' ', text);
     if (should_interpret_backslash_escapes)
         output = interpret_backslash_escapes(output, no_trailing_newline);
     out("{}", output);
diff --git a/Userland/Utilities/env.cpp b/Userland/Utilities/env.cpp
index c1857973115..39d4c05e80b 100644
--- a/Userland/Utilities/env.cpp
+++ b/Userland/Utilities/env.cpp
@@ -17,8 +17,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     bool ignore_env = false;
     StringView split_string {};
-    Vector<DeprecatedString> values_to_set;
-    Vector<DeprecatedString> values_to_unset;
+    Vector<ByteString> values_to_set;
+    Vector<ByteString> values_to_unset;
 
     Core::ArgsParser args_parser;
     args_parser.set_stop_on_first_non_option(true);
diff --git a/Userland/Utilities/expr.cpp b/Userland/Utilities/expr.cpp
index 2af361b66c8..4a8aa9d33dd 100644
--- a/Userland/Utilities/expr.cpp
+++ b/Userland/Utilities/expr.cpp
@@ -5,7 +5,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/GenericLexer.h>
 #include <AK/NonnullOwnPtr.h>
 #include <AK/OwnPtr.h>
@@ -56,7 +56,7 @@ public:
 
     virtual bool truth() const = 0;
     virtual int integer() const = 0;
-    virtual DeprecatedString string() const = 0;
+    virtual ByteString string() const = 0;
     virtual Type type() const = 0;
     virtual ~Expression() = default;
 };
@@ -69,7 +69,7 @@ public:
     {
     }
 
-    ValueExpression(DeprecatedString&& v)
+    ValueExpression(ByteString&& v)
         : as_string(move(v))
         , m_type(Type::String)
     {
@@ -96,11 +96,11 @@ private:
         }
         VERIFY_NOT_REACHED();
     }
-    virtual DeprecatedString string() const override
+    virtual ByteString string() const override
     {
         switch (m_type) {
         case Type::Integer:
-            return DeprecatedString::formatted("{}", as_integer);
+            return ByteString::formatted("{}", as_integer);
         case Type::String:
             return as_string;
         }
@@ -110,7 +110,7 @@ private:
 
     union {
         int as_integer;
-        DeprecatedString as_string;
+        ByteString as_string;
     };
     Type m_type { Type::String };
 };
@@ -161,7 +161,7 @@ private:
         VERIFY_NOT_REACHED();
     }
 
-    virtual DeprecatedString string() const override
+    virtual ByteString string() const override
     {
         switch (m_op) {
         case BooleanOperator::And:
@@ -260,7 +260,7 @@ private:
         VERIFY_NOT_REACHED();
     }
     virtual int integer() const override { return truth(); }
-    virtual DeprecatedString string() const override { return truth() ? "1" : "0"; }
+    virtual ByteString string() const override { return truth() ? "1" : "0"; }
     virtual Type type() const override { return Type::Integer; }
 
     ComparisonOperation m_op { ComparisonOperation::Less };
@@ -330,9 +330,9 @@ private:
         }
         VERIFY_NOT_REACHED();
     }
-    virtual DeprecatedString string() const override
+    virtual ByteString string() const override
     {
-        return DeprecatedString::formatted("{}", integer());
+        return ByteString::formatted("{}", integer());
     }
     virtual Type type() const override
     {
@@ -388,7 +388,7 @@ private:
 
         VERIFY_NOT_REACHED();
     }
-    static auto safe_substring(DeprecatedString const& str, int start, int length)
+    static auto safe_substring(ByteString const& str, int start, int length)
     {
         if (start < 1 || (size_t)start > str.length())
             fail("Index out of range");
@@ -397,7 +397,7 @@ private:
             fail("Index out of range");
         return str.substring(start, length);
     }
-    virtual DeprecatedString string() const override
+    virtual ByteString string() const override
     {
         if (m_op == StringOperation::Substring)
             return safe_substring(m_str->string(), m_pos_or_chars->integer(), m_length->integer());
@@ -412,7 +412,7 @@ private:
                 for (auto& m : match.matches)
                     count += m.view.length();
 
-                return DeprecatedString::number(count);
+                return ByteString::number(count);
             } else {
                 if (!match.success)
                     return "";
@@ -421,11 +421,11 @@ private:
                 for (auto& e : match.capture_group_matches[0])
                     result.append(e.view.string_view());
 
-                return result.to_deprecated_string();
+                return result.to_byte_string();
             }
         }
 
-        return DeprecatedString::number(integer());
+        return ByteString::number(integer());
     }
     virtual Type type() const override
     {
diff --git a/Userland/Utilities/fdtdump.cpp b/Userland/Utilities/fdtdump.cpp
index 106c9997ba0..3e484535126 100644
--- a/Userland/Utilities/fdtdump.cpp
+++ b/Userland/Utilities/fdtdump.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/MappedFile.h>
 #include <LibCore/System.h>
@@ -16,7 +16,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio rpath"));
 
-    DeprecatedString filename;
+    ByteString filename;
 
     Core::ArgsParser args;
     args.add_positional_argument(filename, "File to process", "file", Core::ArgsParser::Required::Yes);
diff --git a/Userland/Utilities/find.cpp b/Userland/Utilities/find.cpp
index 4e3f870dc46..d76f593c2ea 100644
--- a/Userland/Utilities/find.cpp
+++ b/Userland/Utilities/find.cpp
@@ -62,7 +62,7 @@ struct FileData {
     // File type as returned from readdir(), or DT_UNKNOWN.
     unsigned char d_type { DT_UNKNOWN };
 
-    DeprecatedString full_path() const
+    ByteString full_path() const
     {
         if (root_path.is_empty())
             return relative_path.string();
@@ -73,9 +73,9 @@ struct FileData {
         // POSIX says that a single slash should be added between the root path and the relative portion if the root path doesn't end in one
         // any additional trailing slashes should be left unaltered.
         if (root_path.ends_with('/'))
-            return DeprecatedString::formatted("{}{}", root_path, relative_path.string());
+            return ByteString::formatted("{}{}", root_path, relative_path.string());
 
-        return DeprecatedString::formatted("{}/{}", root_path, relative_path.string());
+        return ByteString::formatted("{}/{}", root_path, relative_path.string());
     }
 
     const struct stat* ensure_stat()
@@ -579,7 +579,7 @@ private:
             auto full_path_or_error = FileSystem::real_path(file_data.full_path());
             if (!full_path_or_error.is_error()) {
                 auto fullpath = full_path_or_error.release_value();
-                auto url = URL::create_with_file_scheme(fullpath.to_deprecated_string());
+                auto url = URL::create_with_file_scheme(fullpath.to_byte_string());
                 out("\033]8;;{}\033\\{}{}\033]8;;\033\\", url.serialize(), file_data.full_path(), m_terminator);
                 printed = true;
             }
@@ -611,7 +611,7 @@ private:
     virtual bool evaluate(FileData& file_data) const override
     {
         // Replace any occurrences of "{}" with the path.
-        Vector<DeprecatedString> full_paths;
+        Vector<ByteString> full_paths;
         Vector<char*> argv = m_argv;
         for (auto& arg : argv) {
             if (StringView { arg, strlen(arg) } == "{}") {
@@ -1030,8 +1030,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     for (auto& path : paths) {
         LexicalPath lexical_path { path };
-        DeprecatedString dirname = lexical_path.dirname();
-        DeprecatedString basename = lexical_path.basename();
+        ByteString dirname = lexical_path.dirname();
+        ByteString basename = lexical_path.basename();
 
         int dirfd = TRY(Core::System::open(dirname, O_RDONLY | O_DIRECTORY | O_CLOEXEC));
 
diff --git a/Userland/Utilities/fortune.cpp b/Userland/Utilities/fortune.cpp
index 62bf908230e..d059a74557f 100644
--- a/Userland/Utilities/fortune.cpp
+++ b/Userland/Utilities/fortune.cpp
@@ -30,30 +30,30 @@ public:
         if (!entry.has_string("quote"sv) || !entry.has_string("author"sv) || !entry.has_u64("utc_time"sv) || !entry.has_string("url"sv))
             return {};
         // From here on, trust that it's probably fine.
-        q.m_quote = entry.get_deprecated_string("quote"sv).value();
-        q.m_author = entry.get_deprecated_string("author"sv).value();
+        q.m_quote = entry.get_byte_string("quote"sv).value();
+        q.m_author = entry.get_byte_string("author"sv).value();
         q.m_utc_time = entry.get_u64("utc_time"sv).value();
-        q.m_url = entry.get_deprecated_string("url"sv).value();
+        q.m_url = entry.get_byte_string("url"sv).value();
         if (entry.has("context"sv))
-            q.m_context = entry.get_deprecated_string("context"sv).value();
+            q.m_context = entry.get_byte_string("context"sv).value();
 
         return q;
     }
 
-    DeprecatedString const& quote() const { return m_quote; }
-    DeprecatedString const& author() const { return m_author; }
+    ByteString const& quote() const { return m_quote; }
+    ByteString const& author() const { return m_author; }
     u64 const& utc_time() const { return m_utc_time; }
-    DeprecatedString const& url() const { return m_url; }
-    Optional<DeprecatedString> const& context() const { return m_context; }
+    ByteString const& url() const { return m_url; }
+    Optional<ByteString> const& context() const { return m_context; }
 
 private:
     Quote() = default;
 
-    DeprecatedString m_quote;
-    DeprecatedString m_author;
+    ByteString m_quote;
+    ByteString m_author;
     u64 m_utc_time;
-    DeprecatedString m_url;
-    Optional<DeprecatedString> m_context;
+    ByteString m_url;
+    Optional<ByteString> m_context;
 };
 
 static Vector<Quote> parse_all(JsonArray const& array)
@@ -131,11 +131,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
 
     if (show_color) {
-        out("\033[34m({})\033[m", datetime.to_deprecated_string());
+        out("\033[34m({})\033[m", datetime.to_byte_string());
         out(" \033[34;1m<{}>\033[m", chosen_quote.author());
         out(" \033[32m{}\033[m", chosen_quote.quote());
     } else {
-        out("({})", datetime.to_deprecated_string());
+        out("({})", datetime.to_byte_string());
         out(" <{}>", chosen_quote.author());
         out(" {}", chosen_quote.quote());
     }
diff --git a/Userland/Utilities/functrace.cpp b/Userland/Utilities/functrace.cpp
index 5e2f8ef84c0..3a9eac996d4 100644
--- a/Userland/Utilities/functrace.cpp
+++ b/Userland/Utilities/functrace.cpp
@@ -34,7 +34,7 @@ static void handle_sigint(int)
     g_debug_session = nullptr;
 }
 
-static void print_function_call(DeprecatedString function_name, size_t depth)
+static void print_function_call(ByteString function_name, size_t depth)
 {
     for (size_t i = 0; i < depth; ++i) {
         out("  ");
diff --git a/Userland/Utilities/gml-format.cpp b/Userland/Utilities/gml-format.cpp
index 49ef4a48985..102f2e1a1fd 100644
--- a/Userland/Utilities/gml-format.cpp
+++ b/Userland/Utilities/gml-format.cpp
@@ -40,7 +40,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
     TRY(Core::System::pledge("stdio rpath wpath cpath"));
 
     bool inplace = false;
-    Vector<DeprecatedString> files;
+    Vector<ByteString> files;
 
     Core::ArgsParser args_parser;
     args_parser.set_general_help("Format GML files.");
diff --git a/Userland/Utilities/grep.cpp b/Userland/Utilities/grep.cpp
index b6caa0a23bc..d9a85f765b4 100644
--- a/Userland/Utilities/grep.cpp
+++ b/Userland/Utilities/grep.cpp
@@ -6,7 +6,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/ScopeGuard.h>
 #include <AK/StringBuilder.h>
@@ -46,7 +46,7 @@ void fail(StringView format, Ts... args)
 constexpr StringView ere_special_characters = ".^$*+?()[{\\|"sv;
 constexpr StringView basic_special_characters = ".^$*[\\"sv;
 
-static DeprecatedString escape_characters(StringView string, StringView characters)
+static ByteString escape_characters(StringView string, StringView characters)
 {
     StringBuilder builder;
     for (auto ch : string) {
@@ -55,12 +55,12 @@ static DeprecatedString escape_characters(StringView string, StringView characte
 
         builder.append(ch);
     }
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-static DeprecatedString& hostname()
+static ByteString& hostname()
 {
-    static DeprecatedString s_hostname;
+    static ByteString s_hostname;
     if (s_hostname.is_empty()) {
         auto result = Core::System::gethostname();
         if (result.is_error())
@@ -88,7 +88,7 @@ static void append_formatted_path(StringBuilder& builder, StringView path, Optio
         auto full_path_or_error = FileSystem::real_path(path);
         if (!full_path_or_error.is_error()) {
             auto fullpath = full_path_or_error.release_value();
-            auto url = URL::create_with_file_scheme(fullpath.to_deprecated_string(), {}, hostname());
+            auto url = URL::create_with_file_scheme(fullpath.to_byte_string(), {}, hostname());
             if (has_flag(print_type, PrintType::LineNumbers) && line_number.has_value())
                 url.set_query(MUST(String::formatted("line_number={}", *line_number)));
             builder.appendff("\033]8;;{}\033\\", url.serialize());
@@ -117,14 +117,14 @@ ErrorOr<int> serenity_main(Main::Arguments args)
 {
     TRY(Core::System::pledge("stdio rpath"));
 
-    DeprecatedString program_name = AK::LexicalPath::basename(args.strings[0]);
+    ByteString program_name = AK::LexicalPath::basename(args.strings[0]);
 
-    Vector<DeprecatedString> files;
+    Vector<ByteString> files;
 
     bool recursive = (program_name == "rgrep"sv);
     bool use_ere = (program_name == "egrep"sv);
     bool fixed_strings = (program_name == "fgrep"sv);
-    Vector<DeprecatedString> patterns;
+    Vector<ByteString> patterns;
     StringView pattern_file;
     BinaryFileMode binary_mode { BinaryFileMode::Binary };
     bool case_insensitive = false;
@@ -219,7 +219,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
             // should be ignored.
             if (next_pattern.is_empty() && buffered_file->is_eof())
                 break;
-            patterns.append(next_pattern.to_deprecated_string());
+            patterns.append(next_pattern.to_byte_string());
         }
     }
 
@@ -280,7 +280,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
                         auto pre_match_length = match.global_offset - last_printed_char_pos;
                         out(colored_output ? "{}\x1B[32m{}\x1B[0m"sv : "{}{}"sv,
                             pre_match_length > 0 ? StringView(&str[last_printed_char_pos], pre_match_length) : ""sv,
-                            match.view.to_deprecated_string());
+                            match.view.to_byte_string());
                         last_printed_char_pos = match.global_offset + match.view.length();
                     }
                     auto remaining_length = str.length() - last_printed_char_pos;
@@ -328,7 +328,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
             return {};
         };
 
-        auto add_directory = [&handle_file, &exit_status, user_has_specified_files, suppress_errors](DeprecatedString base, Optional<DeprecatedString> recursive, auto handle_directory) -> void {
+        auto add_directory = [&handle_file, &exit_status, user_has_specified_files, suppress_errors](ByteString base, Optional<ByteString> recursive, auto handle_directory) -> void {
             Core::DirIterator it(recursive.value_or(base), Core::DirIterator::Flags::SkipDots);
             while (it.has_next()) {
                 auto path = it.next_full_path();
diff --git a/Userland/Utilities/gron.cpp b/Userland/Utilities/gron.cpp
index 12dc449a157..8c5fe923c2b 100644
--- a/Userland/Utilities/gron.cpp
+++ b/Userland/Utilities/gron.cpp
@@ -15,7 +15,7 @@
 #include <unistd.h>
 
 static bool use_color = false;
-static void print(StringView name, JsonValue const&, Vector<DeprecatedString>& trail);
+static void print(StringView name, JsonValue const&, Vector<ByteString>& trail);
 
 static StringView color_name = ""sv;
 static StringView color_index = ""sv;
@@ -71,12 +71,12 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         color_off = "\033[0m"sv;
     }
 
-    Vector<DeprecatedString> trail;
+    Vector<ByteString> trail;
     print("json"sv, json, trail);
     return 0;
 }
 
-static void print(StringView name, JsonValue const& value, Vector<DeprecatedString>& trail)
+static void print(StringView name, JsonValue const& value, Vector<ByteString>& trail)
 {
     for (size_t i = 0; i < trail.size(); ++i)
         out("{}", trail[i]);
@@ -85,16 +85,16 @@ static void print(StringView name, JsonValue const& value, Vector<DeprecatedStri
 
     if (value.is_object()) {
         outln("{}{{}}{};", color_brace, color_off);
-        trail.append(DeprecatedString::formatted("{}{}{}.", color_name, name, color_off));
+        trail.append(ByteString::formatted("{}{}{}.", color_name, name, color_off));
         value.as_object().for_each_member([&](auto& on, auto& ov) { print(on, ov, trail); });
         trail.take_last();
         return;
     }
     if (value.is_array()) {
         outln("{}[]{};", color_brace, color_off);
-        trail.append(DeprecatedString::formatted("{}{}{}", color_name, name, color_off));
+        trail.append(ByteString::formatted("{}{}{}", color_name, name, color_off));
         for (size_t i = 0; i < value.as_array().size(); ++i) {
-            auto element_name = DeprecatedString::formatted("{}{}[{}{}{}{}{}]{}", color_off, color_brace, color_off, color_index, i, color_off, color_brace, color_off);
+            auto element_name = ByteString::formatted("{}{}[{}{}{}{}{}]{}", color_off, color_brace, color_off, color_index, i, color_off, color_brace, color_off);
             print(element_name, value.as_array()[i], trail);
         }
         trail.take_last();
diff --git a/Userland/Utilities/groupadd.cpp b/Userland/Utilities/groupadd.cpp
index c5a33d21d77..3420205a0df 100644
--- a/Userland/Utilities/groupadd.cpp
+++ b/Userland/Utilities/groupadd.cpp
@@ -21,7 +21,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     gid_t gid = 0;
     StringView group_name;
-    Vector<DeprecatedString> group_members;
+    Vector<ByteString> group_members;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(gid, "Group ID (gid) for the new group", "gid", 'g', "gid");
@@ -36,7 +36,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             if (accounts_or_error.is_error())
                 return false;
 
-            OrderedHashTable<DeprecatedString> unique_group_members;
+            OrderedHashTable<ByteString> unique_group_members;
             auto accounts = accounts_or_error.release_value();
             for (auto const& username : comma_separated_users.split_view(',')) {
                 auto matching_account = accounts.first_matching([&](auto const& account) { return username == account.username(); });
diff --git a/Userland/Utilities/groupdel.cpp b/Userland/Utilities/groupdel.cpp
index 53dbf4e0d68..93194ffc9fa 100644
--- a/Userland/Utilities/groupdel.cpp
+++ b/Userland/Utilities/groupdel.cpp
@@ -21,7 +21,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::unveil("/bin/rm", "x"));
     TRY(Core::System::unveil(nullptr, nullptr));
 
-    DeprecatedString groupname;
+    ByteString groupname;
 
     Core::ArgsParser args_parser;
     args_parser.add_positional_argument(groupname, "Group name", "group");
diff --git a/Userland/Utilities/groups.cpp b/Userland/Utilities/groups.cpp
index c27db72ee43..68b20473175 100644
--- a/Userland/Utilities/groups.cpp
+++ b/Userland/Utilities/groups.cpp
@@ -35,7 +35,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::unveil(nullptr, nullptr));
     TRY(Core::System::pledge("stdio rpath"));
 
-    Vector<DeprecatedString> usernames;
+    Vector<ByteString> usernames;
 
     Core::ArgsParser args_parser;
     args_parser.set_general_help("Print group memberships for each username or, if no username is specified, for the current process.");
diff --git a/Userland/Utilities/gunzip.cpp b/Userland/Utilities/gunzip.cpp
index 28ace09ae3f..8af3542c6f5 100644
--- a/Userland/Utilities/gunzip.cpp
+++ b/Userland/Utilities/gunzip.cpp
@@ -35,13 +35,13 @@ ErrorOr<int> serenity_main(Main::Arguments args)
 
     for (auto filename : filenames) {
 
-        DeprecatedString input_filename;
-        DeprecatedString output_filename;
+        ByteString input_filename;
+        ByteString output_filename;
         if (filename.ends_with(".gz"sv)) {
             input_filename = filename;
             output_filename = filename.substring_view(0, filename.length() - 3);
         } else {
-            input_filename = DeprecatedString::formatted("{}.gz", filename);
+            input_filename = ByteString::formatted("{}.gz", filename);
             output_filename = filename;
         }
 
diff --git a/Userland/Utilities/gzip.cpp b/Userland/Utilities/gzip.cpp
index 83063858562..81fd3873c36 100644
--- a/Userland/Utilities/gzip.cpp
+++ b/Userland/Utilities/gzip.cpp
@@ -30,7 +30,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         keep_input_files = true;
 
     for (auto const& input_filename : filenames) {
-        DeprecatedString output_filename;
+        ByteString output_filename;
         if (decompress) {
             if (!input_filename.ends_with(".gz"sv)) {
                 warnln("unknown suffix for: {}, skipping", input_filename);
@@ -38,7 +38,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             }
             output_filename = input_filename.substring_view(0, input_filename.length() - ".gz"sv.length());
         } else {
-            output_filename = DeprecatedString::formatted("{}.gz", input_filename);
+            output_filename = ByteString::formatted("{}.gz", input_filename);
         }
 
         auto output_stream = write_to_stdout ? TRY(Core::File::standard_output()) : TRY(Core::File::open(output_filename, Core::File::OpenMode::Write));
diff --git a/Userland/Utilities/head.cpp b/Userland/Utilities/head.cpp
index 171daefe581..b2ec7318f00 100644
--- a/Userland/Utilities/head.cpp
+++ b/Userland/Utilities/head.cpp
@@ -14,7 +14,7 @@
 #include <string.h>
 #include <unistd.h>
 
-int head(DeprecatedString const& filename, bool print_filename, ssize_t line_count, ssize_t byte_count);
+int head(ByteString const& filename, bool print_filename, ssize_t line_count, ssize_t byte_count);
 
 ErrorOr<int> serenity_main(Main::Arguments args)
 {
@@ -24,7 +24,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
     int byte_count = -1;
     bool never_print_filenames = false;
     bool always_print_filenames = false;
-    Vector<DeprecatedString> files;
+    Vector<ByteString> files;
 
     Core::ArgsParser args_parser;
     args_parser.set_general_help("Print the beginning ('head') of a file.");
@@ -60,7 +60,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
     return rc;
 }
 
-int head(DeprecatedString const& filename, bool print_filename, ssize_t line_count, ssize_t byte_count)
+int head(ByteString const& filename, bool print_filename, ssize_t line_count, ssize_t byte_count)
 {
     bool is_stdin = false;
     int fd = -1;
diff --git a/Userland/Utilities/headless-browser.cpp b/Userland/Utilities/headless-browser.cpp
index dbb3fc781cd..0fcebf0382c 100644
--- a/Userland/Utilities/headless-browser.cpp
+++ b/Userland/Utilities/headless-browser.cpp
@@ -8,7 +8,7 @@
  */
 
 #include <AK/Badge.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Function.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonParser.h>
@@ -90,17 +90,17 @@ public:
 
     ErrorOr<String> dump_layout_tree()
     {
-        return String::from_deprecated_string(client().dump_layout_tree());
+        return String::from_byte_string(client().dump_layout_tree());
     }
 
     ErrorOr<String> dump_paint_tree()
     {
-        return String::from_deprecated_string(client().dump_paint_tree());
+        return String::from_byte_string(client().dump_paint_tree());
     }
 
     ErrorOr<String> dump_text()
     {
-        return String::from_deprecated_string(client().dump_text());
+        return String::from_byte_string(client().dump_text());
     }
 
     void clear_content_filters()
@@ -190,7 +190,7 @@ static ErrorOr<TestResult> run_dump_test(HeadlessWebContentView& view, StringVie
         loop.quit(0);
     }));
 
-    view.load(URL::create_with_file_scheme(TRY(FileSystem::real_path(input_path)).to_deprecated_string()));
+    view.load(URL::create_with_file_scheme(TRY(FileSystem::real_path(input_path)).to_byte_string()));
 
     String result;
 
@@ -266,7 +266,7 @@ static ErrorOr<TestResult> run_ref_test(HeadlessWebContentView& view, StringView
         loop.quit(0);
     }));
 
-    view.load(URL::create_with_file_scheme(TRY(FileSystem::real_path(input_path)).to_deprecated_string()));
+    view.load(URL::create_with_file_scheme(TRY(FileSystem::real_path(input_path)).to_byte_string()));
 
     RefPtr<Gfx::Bitmap> actual_screenshot, expectation_screenshot;
     view.on_load_finish = [&](auto const&) {
@@ -332,7 +332,7 @@ struct Test {
     Optional<TestResult> result;
 };
 
-static Vector<DeprecatedString> s_skipped_tests;
+static Vector<ByteString> s_skipped_tests;
 
 static ErrorOr<void> load_test_config(StringView test_root_path)
 {
@@ -361,7 +361,7 @@ static ErrorOr<void> load_test_config(StringView test_root_path)
 
 static ErrorOr<void> collect_dump_tests(Vector<Test>& tests, StringView path, StringView trail, TestMode mode)
 {
-    Core::DirIterator it(TRY(String::formatted("{}/input/{}", path, trail)).to_deprecated_string(), Core::DirIterator::Flags::SkipDots);
+    Core::DirIterator it(TRY(String::formatted("{}/input/{}", path, trail)).to_byte_string(), Core::DirIterator::Flags::SkipDots);
     while (it.has_next()) {
         auto name = it.next_path();
         auto input_path = TRY(FileSystem::real_path(TRY(String::formatted("{}/input/{}/{}", path, trail, name))));
diff --git a/Userland/Utilities/host.cpp b/Userland/Utilities/host.cpp
index c7404488219..7506ababd79 100644
--- a/Userland/Utilities/host.cpp
+++ b/Userland/Utilities/host.cpp
@@ -17,7 +17,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
 {
     TRY(Core::System::pledge("stdio unix"));
 
-    DeprecatedString name_or_ip {};
+    ByteString name_or_ip {};
     Core::ArgsParser args_parser;
     args_parser.set_general_help("Convert between domain name and IPv4 address.");
     args_parser.add_positional_argument(name_or_ip, "Domain name or IPv4 address", "name");
diff --git a/Userland/Utilities/id.cpp b/Userland/Utilities/id.cpp
index a10fdf9e8f4..28b01002fd9 100644
--- a/Userland/Utilities/id.cpp
+++ b/Userland/Utilities/id.cpp
@@ -21,7 +21,7 @@ static bool flag_print_uid = false;
 static bool flag_print_gid = false;
 static bool flag_print_name = false;
 static bool flag_print_gid_all = false;
-static DeprecatedString user_str;
+static ByteString user_str;
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
diff --git a/Userland/Utilities/ifconfig.cpp b/Userland/Utilities/ifconfig.cpp
index b074fa1d3d7..f2f86f49237 100644
--- a/Userland/Utilities/ifconfig.cpp
+++ b/Userland/Utilities/ifconfig.cpp
@@ -38,11 +38,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         json.as_array().for_each([](auto& value) {
             auto& if_object = value.as_object();
 
-            auto name = if_object.get_deprecated_string("name"sv).value_or({});
-            auto class_name = if_object.get_deprecated_string("class_name"sv).value_or({});
-            auto mac_address = if_object.get_deprecated_string("mac_address"sv).value_or({});
-            auto ipv4_address = if_object.get_deprecated_string("ipv4_address"sv).value_or({});
-            auto netmask = if_object.get_deprecated_string("ipv4_netmask"sv).value_or({});
+            auto name = if_object.get_byte_string("name"sv).value_or({});
+            auto class_name = if_object.get_byte_string("class_name"sv).value_or({});
+            auto mac_address = if_object.get_byte_string("mac_address"sv).value_or({});
+            auto ipv4_address = if_object.get_byte_string("ipv4_address"sv).value_or({});
+            auto netmask = if_object.get_byte_string("ipv4_netmask"sv).value_or({});
             auto packets_in = if_object.get_u32("packets_in"sv).value_or(0);
             auto bytes_in = if_object.get_u32("bytes_in"sv).value_or(0);
             auto packets_out = if_object.get_u32("packets_out"sv).value_or(0);
@@ -66,7 +66,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             return 1;
         }
 
-        DeprecatedString ifname = value_adapter;
+        ByteString ifname = value_adapter;
 
         if (!value_ipv4.is_empty()) {
             auto address = IPv4Address::from_string(value_ipv4);
diff --git a/Userland/Utilities/image2bin.cpp b/Userland/Utilities/image2bin.cpp
index 935ea3421c8..9c81abce755 100644
--- a/Userland/Utilities/image2bin.cpp
+++ b/Userland/Utilities/image2bin.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Random.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/ArgsParser.h>
@@ -17,7 +17,7 @@
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio rpath unix"));
-    DeprecatedString path;
+    ByteString path;
 
     Core::ArgsParser args_parser;
     args_parser.add_positional_argument(path, "Path to image", "path");
diff --git a/Userland/Utilities/ini.cpp b/Userland/Utilities/ini.cpp
index 90de609e741..0098d6b3391 100644
--- a/Userland/Utilities/ini.cpp
+++ b/Userland/Utilities/ini.cpp
@@ -15,8 +15,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::pledge("stdio rpath wpath cpath"));
 
     StringView path;
-    DeprecatedString group;
-    DeprecatedString key;
+    ByteString group;
+    ByteString key;
     StringView value_to_write;
 
     Core::ArgsParser args_parser;
diff --git a/Userland/Utilities/install.cpp b/Userland/Utilities/install.cpp
index 2c2ef4478f7..b9ff71ed34f 100644
--- a/Userland/Utilities/install.cpp
+++ b/Userland/Utilities/install.cpp
@@ -32,15 +32,15 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     auto permission_mask = TRY(Core::FilePermissionsMask::parse(mode));
 
-    DeprecatedString destination_dir = (sources.size() > 1 ? DeprecatedString { destination } : LexicalPath::dirname(destination));
+    ByteString destination_dir = (sources.size() > 1 ? ByteString { destination } : LexicalPath::dirname(destination));
 
     if (create_leading_dest_components) {
         String destination_dir_absolute = TRY(FileSystem::absolute_path(destination_dir));
-        MUST(Core::Directory::create(destination_dir_absolute.to_deprecated_string(), Core::Directory::CreateDirectories::Yes));
+        MUST(Core::Directory::create(destination_dir_absolute.to_byte_string(), Core::Directory::CreateDirectories::Yes));
     }
 
     for (auto const& source : sources) {
-        DeprecatedString final_destination;
+        ByteString final_destination;
         if (sources.size() > 1) {
             final_destination = LexicalPath(destination).append(LexicalPath::basename(source)).string();
         } else {
diff --git a/Userland/Utilities/js.cpp b/Userland/Utilities/js.cpp
index bc6fa32c921..87d704c6c4f 100644
--- a/Userland/Utilities/js.cpp
+++ b/Userland/Utilities/js.cpp
@@ -120,7 +120,7 @@ static ErrorOr<String> read_next_piece()
     auto line_level_delta_for_next_line { 0 };
 
     do {
-        auto line_result = s_editor->get_line(TRY(prompt_for_level(s_repl_line_level)).to_deprecated_string());
+        auto line_result = s_editor->get_line(TRY(prompt_for_level(s_repl_line_level)).to_byte_string());
 
         line_level_delta_for_next_line = 0;
 
@@ -276,7 +276,7 @@ static JS::ThrowCompletionOr<JS::Value> load_ini_impl(JS::VM& vm)
 {
     auto& realm = *vm.current_realm();
 
-    auto filename = TRY(vm.argument(0).to_deprecated_string(vm));
+    auto filename = TRY(vm.argument(0).to_byte_string(vm));
     auto file_or_error = Core::File::open(filename, Core::File::OpenMode::Read);
     if (file_or_error.is_error())
         return vm.throw_completion<JS::Error>(TRY_OR_THROW_OOM(vm, String::formatted("Failed to open '{}': {}", filename, file_or_error.error())));
@@ -599,12 +599,12 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         auto& global_environment = realm.global_environment();
 
         s_editor = Line::Editor::construct();
-        s_editor->load_history(s_history_path.to_deprecated_string());
+        s_editor->load_history(s_history_path.to_byte_string());
 
         signal(SIGINT, [](int) {
             if (!s_editor->is_editing())
                 sigint_handler();
-            s_editor->save_history(s_history_path.to_deprecated_string());
+            s_editor->save_history(s_history_path.to_byte_string());
         });
 
         s_editor->on_display_refresh = [syntax_highlight](Line::Editor& editor) {
@@ -667,7 +667,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 }
             }
 
-            editor.set_prompt(prompt_for_level(open_indents).release_value_but_fixme_should_propagate_errors().to_deprecated_string());
+            editor.set_prompt(prompt_for_level(open_indents).release_value_but_fixme_should_propagate_errors().to_byte_string());
         };
 
         auto complete = [&realm, &global_environment](Line::Editor const& editor) -> Vector<Line::CompletionSuggestion> {
@@ -749,7 +749,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                     if (key.view().starts_with(property_pattern)) {
                         Line::CompletionSuggestion completion { key, Line::CompletionSuggestion::ForSearch };
                         if (!results.contains_slow(completion)) { // hide duplicates
-                            results.append(DeprecatedString(key));
+                            results.append(ByteString(key));
                             results.last().invariant_offset = property_pattern.length();
                         }
                     }
@@ -799,7 +799,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         };
         s_editor->on_tab_complete = move(complete);
         TRY(repl(realm));
-        s_editor->save_history(s_history_path.to_deprecated_string());
+        s_editor->save_history(s_history_path.to_byte_string());
     } else {
         OwnPtr<JS::ExecutionContext> root_execution_context;
         if (use_test262_global)
diff --git a/Userland/Utilities/json.cpp b/Userland/Utilities/json.cpp
index 6fd5addedc5..467a8fdcc9b 100644
--- a/Userland/Utilities/json.cpp
+++ b/Userland/Utilities/json.cpp
@@ -110,7 +110,7 @@ void print(JsonValue const& value, int spaces_per_indent, int indent, bool use_c
     }
     if (value.is_string())
         out("\"");
-    out("{}", value.to_deprecated_string());
+    out("{}", value.to_byte_string());
     if (value.is_string())
         out("\"");
     if (use_color)
diff --git a/Userland/Utilities/keymap.cpp b/Userland/Utilities/keymap.cpp
index 3b03cd7edec..e3ff29b2e95 100644
--- a/Userland/Utilities/keymap.cpp
+++ b/Userland/Utilities/keymap.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/ConfigFile.h>
@@ -13,9 +13,9 @@
 #include <LibMain/Main.h>
 #include <stdio.h>
 
-int set_keymap(DeprecatedString const& keymap);
+int set_keymap(ByteString const& keymap);
 
-int set_keymap(DeprecatedString const& keymap)
+int set_keymap(ByteString const& keymap)
 {
     auto character_map = Keyboard::CharacterMap::load_from_file(keymap);
     if (character_map.is_error()) {
@@ -38,8 +38,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::unveil("/res/keymaps", "r"));
     TRY(Core::System::unveil("/etc/Keyboard.ini", "rwc"));
 
-    DeprecatedString mapping;
-    DeprecatedString mappings;
+    ByteString mapping;
+    ByteString mappings;
     Core::ArgsParser args_parser;
     args_parser.add_option(mapping, "The mapping to be used", "set-keymap", 'm', "keymap");
     args_parser.add_option(mappings, "Comma separated list of enabled mappings", "set-keymaps", 's', "keymaps");
@@ -71,7 +71,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             }
         }
 
-        auto keymaps = DeprecatedString::join(',', mappings_vector);
+        auto keymaps = ByteString::join(',', mappings_vector);
         mapper_config->write_entry("Mapping", "Keymaps", keymaps);
         TRY(mapper_config->sync());
     }
diff --git a/Userland/Utilities/ldd.cpp b/Userland/Utilities/ldd.cpp
index 632e5aa17b4..ac14a22654a 100644
--- a/Userland/Utilities/ldd.cpp
+++ b/Userland/Utilities/ldd.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
@@ -22,16 +22,16 @@
 #include <stdio.h>
 #include <unistd.h>
 
-static Vector<DeprecatedString> found_libraries;
+static Vector<ByteString> found_libraries;
 
 static ErrorOr<void> recusively_resolve_all_necessary_libraries(StringView interpreter_path, size_t recursive_iteration_max, size_t recursive_iteration, ELF::DynamicObject& object)
 {
     if (recursive_iteration > recursive_iteration_max)
         return ELOOP;
 
-    Vector<DeprecatedString> libraries;
+    Vector<ByteString> libraries;
     object.for_each_needed_library([&libraries](StringView entry) {
-        libraries.append(DeprecatedString::formatted("{}", entry));
+        libraries.append(ByteString::formatted("{}", entry));
     });
     for (auto& library_name : libraries) {
         auto possible_library_path = ELF::DynamicLinker::resolve_library(library_name, object);
@@ -82,7 +82,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio rpath map_fixed"));
 
-    DeprecatedString path {};
+    ByteString path {};
     Optional<size_t> recursive_iteration_max;
     bool force_without_valid_interpreter = false;
 
diff --git a/Userland/Utilities/less.cpp b/Userland/Utilities/less.cpp
index 53ebfb409f8..e622aa710ab 100644
--- a/Userland/Utilities/less.cpp
+++ b/Userland/Utilities/less.cpp
@@ -53,7 +53,7 @@ static void teardown_tty()
         out("\e[?1047l\e[u");
 }
 
-static Vector<StringView> wrap_line(DeprecatedString const& string, size_t width)
+static Vector<StringView> wrap_line(ByteString const& string, size_t width)
 {
     auto const result = Line::Editor::actual_rendered_string_metrics(string, {}, width);
 
@@ -286,7 +286,7 @@ public:
         if (line[size - 1] == '\n')
             --size;
 
-        m_lines.append(DeprecatedString(line, size));
+        m_lines.append(ByteString(line, size));
         return true;
     }
 
@@ -464,7 +464,7 @@ private:
     }
 
     // FIXME: Don't save scrollback when emulating more.
-    Vector<DeprecatedString> m_lines;
+    Vector<ByteString> m_lines;
 
     size_t m_line { 0 };
     size_t m_subline { 0 };
@@ -479,22 +479,22 @@ private:
     size_t m_width { 0 };
     size_t m_height { 0 };
 
-    DeprecatedString m_filename;
-    DeprecatedString m_prompt;
+    ByteString m_filename;
+    ByteString m_prompt;
 
     bool m_show_line_numbers { false };
 };
 
 /// Return the next key sequence, or nothing if a signal is received while waiting
 /// to read the next sequence.
-static Optional<DeprecatedString> get_key_sequence()
+static Optional<ByteString> get_key_sequence()
 {
     // We need a buffer to handle ansi sequences.
     char buff[8];
 
     ssize_t n = read(STDOUT_FILENO, buff, sizeof(buff));
     if (n > 0) {
-        return DeprecatedString(buff, n);
+        return ByteString(buff, n);
     } else {
         return {};
     }
@@ -523,8 +523,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::pledge("stdio rpath tty sigaction"));
 
     // FIXME: Make these into StringViews once we stop using fopen below.
-    DeprecatedString filename = "-";
-    DeprecatedString prompt = "?f%f :.(line %l)?e (END):.";
+    ByteString filename = "-";
+    ByteString prompt = "?f%f :.(line %l)?e (END):.";
     bool dont_switch_buffer = false;
     bool quit_at_eof = false;
     bool quit_if_one_screen = false;
@@ -545,7 +545,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.parse(arguments);
 
     FILE* file;
-    if (DeprecatedString("-") == filename) {
+    if (ByteString("-") == filename) {
         file = stdin;
     } else if ((file = fopen(filename.characters(), "r")) == nullptr) {
         perror("fopen");
@@ -604,7 +604,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     pager.init();
 
     StringBuilder modifier_buffer = StringBuilder(10);
-    for (Optional<DeprecatedString> sequence_value;; sequence_value = get_key_sequence()) {
+    for (Optional<ByteString> sequence_value;; sequence_value = get_key_sequence()) {
         if (g_resized) {
             g_resized = false;
             pager.resize();
@@ -624,28 +624,28 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             } else if (sequence == "j" || sequence == "\e[B" || sequence == "\n") {
                 if (!emulate_more) {
                     if (!modifier_buffer.is_empty())
-                        pager.down_n(modifier_buffer.to_deprecated_string().to_uint().value_or(1));
+                        pager.down_n(modifier_buffer.to_byte_string().to_uint().value_or(1));
                     else
                         pager.down();
                 }
             } else if (sequence == "k" || sequence == "\e[A") {
                 if (!emulate_more) {
                     if (!modifier_buffer.is_empty())
-                        pager.up_n(modifier_buffer.to_deprecated_string().to_uint().value_or(1));
+                        pager.up_n(modifier_buffer.to_byte_string().to_uint().value_or(1));
                     else
                         pager.up();
                 }
             } else if (sequence == "g") {
                 if (!emulate_more) {
                     if (!modifier_buffer.is_empty())
-                        pager.go_to_line(modifier_buffer.to_deprecated_string().to_uint().value());
+                        pager.go_to_line(modifier_buffer.to_byte_string().to_uint().value());
                     else
                         pager.top();
                 }
             } else if (sequence == "G") {
                 if (!emulate_more) {
                     if (!modifier_buffer.is_empty())
-                        pager.go_to_line(modifier_buffer.to_deprecated_string().to_uint().value());
+                        pager.go_to_line(modifier_buffer.to_byte_string().to_uint().value());
                     else
                         pager.bottom();
                 }
diff --git a/Userland/Utilities/ln.cpp b/Userland/Utilities/ln.cpp
index 8d84257297b..2b6cea5f234 100644
--- a/Userland/Utilities/ln.cpp
+++ b/Userland/Utilities/ln.cpp
@@ -24,7 +24,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.add_positional_argument(path, "Link path", "path", Core::ArgsParser::Required::No);
     args_parser.parse(arguments);
 
-    DeprecatedString path_buffer;
+    ByteString path_buffer;
     if (path.is_empty()) {
         path_buffer = LexicalPath::basename(target);
         path = path_buffer.view();
diff --git a/Userland/Utilities/ls.cpp b/Userland/Utilities/ls.cpp
index 9611c39c60d..adcc6006efd 100644
--- a/Userland/Utilities/ls.cpp
+++ b/Userland/Utilities/ls.cpp
@@ -5,7 +5,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/NumberFormat.h>
 #include <AK/QuickSort.h>
@@ -36,8 +36,8 @@
 #include <unistd.h>
 
 struct FileMetadata {
-    DeprecatedString name;
-    DeprecatedString path;
+    ByteString name;
+    ByteString path;
     ino_t raw_inode_number;
     struct stat stat {
     };
@@ -60,8 +60,8 @@ enum class IndicatorStyle {
 };
 AK_ENUM_BITWISE_OPERATORS(IndicatorStyle)
 
-static int do_file_system_object_long(DeprecatedString const& path);
-static int do_file_system_object_short(DeprecatedString const& path);
+static int do_file_system_object_long(ByteString const& path);
+static int do_file_system_object_short(ByteString const& path);
 
 static bool print_names(char const* path, size_t longest_name, Vector<FileMetadata> const& files);
 
@@ -91,8 +91,8 @@ static size_t terminal_rows = 0;
 static size_t terminal_columns = 0;
 static bool output_is_terminal = false;
 
-static HashMap<uid_t, DeprecatedString> users;
-static HashMap<gid_t, DeprecatedString> groups;
+static HashMap<uid_t, ByteString> users;
+static HashMap<gid_t, ByteString> groups;
 
 static bool is_a_tty = false;
 
@@ -162,7 +162,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         endgrent();
     }
 
-    auto do_file_system_object = [&](DeprecatedString const& path) {
+    auto do_file_system_object = [&](ByteString const& path) {
         if (flag_long)
             return do_file_system_object_long(path);
         return do_file_system_object_short(path);
@@ -176,7 +176,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         FileMetadata metadata {};
         metadata.name = path;
 
-        int rc = lstat(DeprecatedString(path).characters(), &metadata.stat);
+        int rc = lstat(ByteString(path).characters(), &metadata.stat);
         if (rc < 0) {
             perror("lstat");
             continue;
@@ -201,7 +201,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             }
 
             while (di.has_next()) {
-                DeprecatedString directory = di.next_full_path();
+                ByteString directory = di.next_full_path();
                 if (FileSystem::is_directory(directory) && !FileSystem::is_link(directory)) {
                     ++subdirs;
                     FileMetadata new_file;
@@ -248,9 +248,9 @@ static int print_escaped(StringView name)
     return printed;
 }
 
-static DeprecatedString& hostname()
+static ByteString& hostname()
 {
-    static Optional<DeprecatedString> s_hostname;
+    static Optional<ByteString> s_hostname;
     if (!s_hostname.has_value()) {
         char buffer[HOST_NAME_MAX];
         if (gethostname(buffer, sizeof(buffer)) == 0)
@@ -261,13 +261,13 @@ static DeprecatedString& hostname()
     return *s_hostname;
 }
 
-static size_t print_name(const struct stat& st, DeprecatedString const& name, Optional<StringView> path_for_link_resolution, StringView path_for_hyperlink)
+static size_t print_name(const struct stat& st, ByteString const& name, Optional<StringView> path_for_link_resolution, StringView path_for_hyperlink)
 {
     if (!flag_disable_hyperlinks) {
         auto full_path_or_error = FileSystem::real_path(path_for_hyperlink);
         if (!full_path_or_error.is_error()) {
             auto fullpath = full_path_or_error.release_value();
-            auto url = URL::create_with_file_scheme(fullpath.to_deprecated_string(), {}, hostname());
+            auto url = URL::create_with_file_scheme(fullpath.to_byte_string(), {}, hostname());
             out("\033]8;;{}\033\\", url.serialize());
         }
     }
@@ -334,13 +334,13 @@ static size_t print_name(const struct stat& st, DeprecatedString const& name, Op
     return nprinted;
 }
 
-static bool print_filesystem_object(DeprecatedString const& path, DeprecatedString const& name, const struct stat& st, Optional<ino_t> raw_inode_number)
+static bool print_filesystem_object(ByteString const& path, ByteString const& name, const struct stat& st, Optional<ino_t> raw_inode_number)
 {
     if (flag_show_inode) {
-        printf("%s ", DeprecatedString::formatted("{}", st.st_ino).characters());
+        printf("%s ", ByteString::formatted("{}", st.st_ino).characters());
     } else if (flag_show_raw_inode) {
         if (raw_inode_number.has_value())
-            printf("%s ", DeprecatedString::formatted("{}", raw_inode_number.value()).characters());
+            printf("%s ", ByteString::formatted("{}", raw_inode_number.value()).characters());
         else
             printf("n/a ");
     }
@@ -409,7 +409,7 @@ static bool print_filesystem_object(DeprecatedString const& path, DeprecatedStri
         }
     }
 
-    printf("  %s  ", Core::DateTime::from_timestamp(st.st_mtime).to_deprecated_string().characters());
+    printf("  %s  ", Core::DateTime::from_timestamp(st.st_mtime).to_byte_string().characters());
 
     print_name(st, name, path.view(), path);
 
@@ -422,7 +422,7 @@ static bool print_filesystem_metadata_object(FileMetadata const& file)
     return print_filesystem_object(file.path, file.name, file.stat, file.raw_inode_number);
 }
 
-static int do_file_system_object_long(DeprecatedString const& path)
+static int do_file_system_object_long(ByteString const& path)
 {
     if (flag_list_directories_only) {
         struct stat stat {
@@ -478,7 +478,7 @@ static int do_file_system_object_long(DeprecatedString const& path)
         builder.append(path);
         builder.append('/');
         builder.append(metadata.name);
-        metadata.path = builder.to_deprecated_string();
+        metadata.path = builder.to_byte_string();
         int rc = lstat(metadata.path.characters(), &metadata.stat);
         if (rc < 0)
             perror("lstat");
@@ -495,7 +495,7 @@ static int do_file_system_object_long(DeprecatedString const& path)
     return 0;
 }
 
-static bool print_filesystem_object_short(DeprecatedString const& path, char const* name, Optional<ino_t> raw_inode_number, size_t* nprinted)
+static bool print_filesystem_object_short(ByteString const& path, char const* name, Optional<ino_t> raw_inode_number, size_t* nprinted)
 {
     struct stat st;
     int rc = lstat(path.characters(), &st);
@@ -505,10 +505,10 @@ static bool print_filesystem_object_short(DeprecatedString const& path, char con
     }
 
     if (flag_show_inode) {
-        printf("%s ", DeprecatedString::formatted("{}", st.st_ino).characters());
+        printf("%s ", ByteString::formatted("{}", st.st_ino).characters());
     } else if (flag_show_raw_inode) {
         if (raw_inode_number.has_value())
-            printf("%s ", DeprecatedString::formatted("{}", raw_inode_number.value()).characters());
+            printf("%s ", ByteString::formatted("{}", raw_inode_number.value()).characters());
         else
             printf("n/a ");
     }
@@ -527,7 +527,7 @@ static bool print_names(char const* path, size_t longest_name, Vector<FileMetada
         builder.append({ path, strlen(path) });
         builder.append('/');
         builder.append(name);
-        if (!print_filesystem_object_short(builder.to_deprecated_string(), name.characters(), files[i].raw_inode_number, &nprinted))
+        if (!print_filesystem_object_short(builder.to_byte_string(), name.characters(), files[i].raw_inode_number, &nprinted))
             return 2;
         int offset = 0;
         if (terminal_columns > longest_name)
@@ -551,7 +551,7 @@ static bool print_names(char const* path, size_t longest_name, Vector<FileMetada
     return printed_on_row;
 }
 
-int do_file_system_object_short(DeprecatedString const& path)
+int do_file_system_object_short(ByteString const& path)
 {
     if (flag_list_directories_only) {
         if (flag_show_raw_inode)
@@ -602,7 +602,7 @@ int do_file_system_object_short(DeprecatedString const& path)
         builder.append(path);
         builder.append('/');
         builder.append(metadata.name);
-        metadata.path = builder.to_deprecated_string();
+        metadata.path = builder.to_byte_string();
         int rc = lstat(metadata.path.characters(), &metadata.stat);
         if (rc < 0)
             perror("lstat");
diff --git a/Userland/Utilities/lsblk.cpp b/Userland/Utilities/lsblk.cpp
index bc2518a37f4..eac5c043283 100644
--- a/Userland/Utilities/lsblk.cpp
+++ b/Userland/Utilities/lsblk.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Hex.h>
 #include <AK/StringView.h>
 #include <LibCore/ArgsParser.h>
@@ -38,19 +38,19 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     while (di.has_next()) {
         auto dir = di.next_path();
-        auto command_set_filename = DeprecatedString::formatted("/sys/devices/storage/{}/command_set", dir);
+        auto command_set_filename = ByteString::formatted("/sys/devices/storage/{}/command_set", dir);
         auto command_set_file = Core::File::open(command_set_filename, Core::File::OpenMode::Read);
         if (command_set_file.is_error()) {
             dbgln("Error: Could not open {}: {}", command_set_filename, command_set_file.error());
             continue;
         }
-        auto last_lba_filename = DeprecatedString::formatted("/sys/devices/storage/{}/last_lba", dir);
+        auto last_lba_filename = ByteString::formatted("/sys/devices/storage/{}/last_lba", dir);
         auto last_lba_file = Core::File::open(last_lba_filename, Core::File::OpenMode::Read);
         if (last_lba_file.is_error()) {
             dbgln("Error: Could not open {}: {}", last_lba_filename, last_lba_file.error());
             continue;
         }
-        auto sector_size_filename = DeprecatedString::formatted("/sys/devices/storage/{}/sector_size", dir);
+        auto sector_size_filename = ByteString::formatted("/sys/devices/storage/{}/sector_size", dir);
         auto sector_size_file = Core::File::open(sector_size_filename, Core::File::OpenMode::Read);
         if (sector_size_file.is_error()) {
             dbgln("Error: Could not open {}: {}", sector_size_filename, sector_size_file.error());
@@ -62,21 +62,21 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             dbgln("Error: Could not read {}: {}", command_set_filename, maybe_command_set.error());
             continue;
         }
-        DeprecatedString command_set = StringView(maybe_command_set.value().bytes());
+        ByteString command_set = StringView(maybe_command_set.value().bytes());
 
         auto maybe_last_lba = last_lba_file.value()->read_until_eof();
         if (maybe_last_lba.is_error()) {
             dbgln("Error: Could not read {}: {}", last_lba_filename, maybe_last_lba.error());
             continue;
         }
-        DeprecatedString last_lba = StringView(maybe_last_lba.value().bytes());
+        ByteString last_lba = StringView(maybe_last_lba.value().bytes());
 
         auto maybe_sector_size = sector_size_file.value()->read_until_eof();
         if (maybe_sector_size.is_error()) {
             dbgln("Error: Could not read {}: {}", sector_size_filename, maybe_sector_size.error());
             continue;
         }
-        DeprecatedString sector_size = StringView(maybe_sector_size.value().bytes());
+        ByteString sector_size = StringView(maybe_sector_size.value().bytes());
 
         outln(format_row, dir, command_set, sector_size, last_lba);
     }
diff --git a/Userland/Utilities/lscpu.cpp b/Userland/Utilities/lscpu.cpp
index 15f1afd3b8c..b71ae946279 100644
--- a/Userland/Utilities/lscpu.cpp
+++ b/Userland/Utilities/lscpu.cpp
@@ -23,10 +23,10 @@ static void print_cache_info(StringView description, JsonObject const& cache_obj
 static void print_cpu_info(JsonObject const& value)
 {
     outln("CPU {}:", value.get_u32("processor"sv).value());
-    outln("\tVendor ID: {}", value.get_deprecated_string("vendor_id"sv).value());
+    outln("\tVendor ID: {}", value.get_byte_string("vendor_id"sv).value());
     if (value.has("hypervisor_vendor_id"sv))
-        outln("\tHypervisor Vendor ID: {}", value.get_deprecated_string("hypervisor_vendor_id"sv).value());
-    outln("\tBrand: {}", value.get_deprecated_string("brand"sv).value());
+        outln("\tHypervisor Vendor ID: {}", value.get_byte_string("hypervisor_vendor_id"sv).value());
+    outln("\tBrand: {}", value.get_byte_string("brand"sv).value());
     outln("\tFamily: {}", value.get_u32("family"sv).value());
     outln("\tModel: {}", value.get_u32("model"sv).value());
     outln("\tStepping: {}", value.get_u32("stepping"sv).value());
diff --git a/Userland/Utilities/lsirq.cpp b/Userland/Utilities/lsirq.cpp
index 076234587bc..c5d9fa22e24 100644
--- a/Userland/Utilities/lsirq.cpp
+++ b/Userland/Utilities/lsirq.cpp
@@ -28,21 +28,21 @@ ErrorOr<int> serenity_main(Main::Arguments)
 
     out("      "sv);
     for (size_t i = 0; i < cpu_count; ++i) {
-        out("{:>10}", DeprecatedString::formatted("CPU{}", i));
+        out("{:>10}", ByteString::formatted("CPU{}", i));
     }
     outln("");
 
     json.as_array().for_each([cpu_count](JsonValue const& value) {
         auto& handler = value.as_object();
-        auto purpose = handler.get_deprecated_string("purpose"sv).value_or({});
+        auto purpose = handler.get_byte_string("purpose"sv).value_or({});
         auto interrupt = handler.get_u8("interrupt_line"sv).value();
-        auto controller = handler.get_deprecated_string("controller"sv).value_or({});
+        auto controller = handler.get_byte_string("controller"sv).value_or({});
         auto call_counts = handler.get_array("per_cpu_call_counts"sv).value();
 
         out("{:>4}: ", interrupt);
 
         for (size_t i = 0; i < cpu_count; ++i)
-            out("{:>10}", call_counts[i].to_deprecated_string());
+            out("{:>10}", call_counts[i].to_byte_string());
 
         outln("  {:10}  {:30}", controller, purpose);
     });
diff --git a/Userland/Utilities/lsjails.cpp b/Userland/Utilities/lsjails.cpp
index 5cfc4abc82f..e6cef4fd760 100644
--- a/Userland/Utilities/lsjails.cpp
+++ b/Userland/Utilities/lsjails.cpp
@@ -25,8 +25,8 @@ ErrorOr<int> serenity_main(Main::Arguments)
     auto json = TRY(JsonValue::from_string(file_contents));
     json.as_array().for_each([](auto& value) {
         auto& jail = value.as_object();
-        auto index = jail.get_deprecated_string("index"sv).value_or({});
-        auto name = jail.get_deprecated_string("name"sv).value_or({});
+        auto index = jail.get_byte_string("index"sv).value_or({});
+        auto name = jail.get_byte_string("name"sv).value_or({});
 
         outln("{:4}     {:10}", index, name);
     });
diff --git a/Userland/Utilities/lsof.cpp b/Userland/Utilities/lsof.cpp
index 53f97724432..f58076301f7 100644
--- a/Userland/Utilities/lsof.cpp
+++ b/Userland/Utilities/lsof.cpp
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/GenericLexer.h>
 #include <AK/JsonArray.h>
 #include <AK/JsonObject.h>
@@ -22,10 +22,10 @@
 struct OpenFile {
     int fd;
     int pid;
-    DeprecatedString type;
-    DeprecatedString name;
-    DeprecatedString state;
-    DeprecatedString full_name;
+    ByteString type;
+    ByteString name;
+    ByteString state;
+    ByteString full_name;
 };
 
 static bool parse_name(StringView name, OpenFile& file)
@@ -66,7 +66,7 @@ static bool parse_name(StringView name, OpenFile& file)
 
 static Vector<OpenFile> get_open_files_by_pid(pid_t pid)
 {
-    auto file = Core::File::open(DeprecatedString::formatted("/proc/{}/fds", pid), Core::File::OpenMode::Read);
+    auto file = Core::File::open(ByteString::formatted("/proc/{}/fds", pid), Core::File::OpenMode::Read);
     if (file.is_error()) {
         outln("lsof: PID {}: {}", pid, file.error());
         return Vector<OpenFile>();
@@ -90,7 +90,7 @@ static Vector<OpenFile> get_open_files_by_pid(pid_t pid)
         open_file.pid = pid;
         open_file.fd = object.as_object().get_integer<int>("fd"sv).value();
 
-        DeprecatedString name = object.as_object().get_deprecated_string("absolute_path"sv).value_or({});
+        ByteString name = object.as_object().get_byte_string("absolute_path"sv).value_or({});
         VERIFY(parse_name(name, open_file));
         open_file.full_name = name;
 
@@ -136,7 +136,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
     {
         // try convert UID to int
-        auto arg = DeprecatedString(arg_uid).to_int();
+        auto arg = ByteString(arg_uid).to_int();
         if (arg.has_value())
             arg_uid_int = arg.value();
     }
diff --git a/Userland/Utilities/lspci.cpp b/Userland/Utilities/lspci.cpp
index b26a03f4a9c..850b51b6ba7 100644
--- a/Userland/Utilities/lspci.cpp
+++ b/Userland/Utilities/lspci.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Hex.h>
 #include <AK/JsonArray.h>
 #include <AK/JsonObject.h>
@@ -29,11 +29,11 @@ static u32 read_hex_string_from_bytebuffer(ByteBuffer const& buf)
 {
     // FIXME: Propagate errors.
     return AK::StringUtils::convert_to_uint_from_hex(
-        DeprecatedString(MUST(buf.slice(2, buf.size() - 2)).bytes()))
+        ByteString(MUST(buf.slice(2, buf.size() - 2)).bytes()))
         .release_value();
 }
 
-static u32 convert_sysfs_value_to_uint(DeprecatedString const& value)
+static u32 convert_sysfs_value_to_uint(ByteString const& value)
 {
     if (auto result = AK::StringUtils::convert_to_uint_from_hex(value); result.has_value())
         return result.release_value();
@@ -89,31 +89,31 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         VERIFY(function_parts.size() == 2);
         auto function = convert_sysfs_value_to_uint(function_parts[1]);
 
-        auto vendor_id_filename = DeprecatedString::formatted("/sys/bus/pci/{}/vendor", dir);
+        auto vendor_id_filename = ByteString::formatted("/sys/bus/pci/{}/vendor", dir);
         auto vendor_id_file = Core::File::open(vendor_id_filename, Core::File::OpenMode::Read);
         if (vendor_id_file.is_error()) {
             dbgln("Error: Could not open {}: {}", vendor_id_filename, vendor_id_file.error());
             continue;
         }
-        auto device_id_filename = DeprecatedString::formatted("/sys/bus/pci/{}/device_id", dir);
+        auto device_id_filename = ByteString::formatted("/sys/bus/pci/{}/device_id", dir);
         auto device_id_file = Core::File::open(device_id_filename, Core::File::OpenMode::Read);
         if (device_id_file.is_error()) {
             dbgln("Error: Could not open {}: {}", device_id_filename, device_id_file.error());
             continue;
         }
-        auto class_id_filename = DeprecatedString::formatted("/sys/bus/pci/{}/class", dir);
+        auto class_id_filename = ByteString::formatted("/sys/bus/pci/{}/class", dir);
         auto class_id_file = Core::File::open(class_id_filename, Core::File::OpenMode::Read);
         if (class_id_file.is_error()) {
             dbgln("Error: Could not open {}: {}", class_id_filename, class_id_file.error());
             continue;
         }
-        auto subclass_id_filename = DeprecatedString::formatted("/sys/bus/pci/{}/subclass", dir);
+        auto subclass_id_filename = ByteString::formatted("/sys/bus/pci/{}/subclass", dir);
         auto subclass_id_file = Core::File::open(subclass_id_filename, Core::File::OpenMode::Read);
         if (subclass_id_file.is_error()) {
             dbgln("Error: Could not open {}: {}", subclass_id_filename, subclass_id_file.error());
             continue;
         }
-        auto revision_id_filename = DeprecatedString::formatted("/sys/bus/pci/{}/revision", dir);
+        auto revision_id_filename = ByteString::formatted("/sys/bus/pci/{}/revision", dir);
         auto revision_id_file = Core::File::open(revision_id_filename, Core::File::OpenMode::Read);
         if (revision_id_file.is_error()) {
             dbgln("Error: Could not open {}: {}", revision_id_filename, revision_id_file.error());
@@ -155,9 +155,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         }
         u32 subclass_id = read_hex_string_from_bytebuffer(subclass_id_contents.value());
 
-        DeprecatedString vendor_name;
-        DeprecatedString device_name;
-        DeprecatedString class_name;
+        ByteString vendor_name;
+        ByteString device_name;
+        ByteString class_name;
 
         if (db) {
             vendor_name = db->get_vendor(vendor_id);
@@ -166,18 +166,18 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         }
 
         if (vendor_name.is_empty())
-            vendor_name = DeprecatedString::formatted("{:04x}", vendor_id);
+            vendor_name = ByteString::formatted("{:04x}", vendor_id);
         if (device_name.is_empty())
-            device_name = DeprecatedString::formatted("{:04x}", device_id);
+            device_name = ByteString::formatted("{:04x}", device_id);
         if (class_name.is_empty())
-            class_name = DeprecatedString::formatted("{:02x}{:02x}", class_id, subclass_id);
+            class_name = ByteString::formatted("{:02x}{:02x}", class_id, subclass_id);
 
         outln(format, domain, bus, device, function, class_name, vendor_name, device_name, revision_id);
 
         if (!flag_verbose)
             continue;
         for (size_t bar_index = 0; bar_index <= 5; bar_index++) {
-            auto bar_value_filename = DeprecatedString::formatted("/sys/bus/pci/{}/bar{}", dir, bar_index);
+            auto bar_value_filename = ByteString::formatted("/sys/bus/pci/{}/bar{}", dir, bar_index);
             auto bar_value_file = Core::File::open(bar_value_filename, Core::File::OpenMode::Read);
             if (bar_value_file.is_error()) {
                 dbgln("Error: Could not open {}: {}", bar_value_filename, bar_value_file.error());
diff --git a/Userland/Utilities/markdown-check.cpp b/Userland/Utilities/markdown-check.cpp
index 8cb4eea9e7e..8457b0a1620 100644
--- a/Userland/Utilities/markdown-check.cpp
+++ b/Userland/Utilities/markdown-check.cpp
@@ -63,9 +63,9 @@ static bool is_missing_file_acceptable(String const& filename)
 }
 
 struct FileLink {
-    DeprecatedString file_path; // May be empty, but not null
-    DeprecatedString anchor;    // May be null ("foo.md", "bar.png"), may be empty ("baz.md#")
-    DeprecatedString label;     // May be empty, but not null
+    ByteString file_path; // May be empty, but not null
+    ByteString anchor;    // May be null ("foo.md", "bar.png"), may be empty ("baz.md#")
+    ByteString label;     // May be empty, but not null
 };
 
 class MarkdownLinkage final : Markdown::Visitor {
@@ -74,8 +74,8 @@ public:
 
     static MarkdownLinkage analyze(Markdown::Document const&, bool verbose);
 
-    bool has_anchor(DeprecatedString const& anchor) const { return m_anchors.contains(anchor); }
-    HashTable<DeprecatedString> const& anchors() const { return m_anchors; }
+    bool has_anchor(ByteString const& anchor) const { return m_anchors.contains(anchor); }
+    HashTable<ByteString> const& anchors() const { return m_anchors; }
     bool has_invalid_link() const { return m_has_invalid_link; }
     Vector<FileLink> const& file_links() const { return m_file_links; }
 
@@ -94,12 +94,12 @@ private:
     virtual RecursionDecision visit(Markdown::Heading const&) override;
     virtual RecursionDecision visit(Markdown::Text::LinkNode const&) override;
 
-    HashTable<DeprecatedString> m_anchors;
+    HashTable<ByteString> m_anchors;
     Vector<FileLink> m_file_links;
     bool m_has_invalid_link { false };
     bool m_verbose { false };
 
-    DeprecatedString m_serenity_source_directory;
+    ByteString m_serenity_source_directory;
 };
 
 MarkdownLinkage MarkdownLinkage::analyze(Markdown::Document const& document, bool verbose)
@@ -116,16 +116,16 @@ public:
     StringCollector() = default;
     virtual ~StringCollector() = default;
 
-    DeprecatedString build() { return m_builder.to_deprecated_string(); }
+    ByteString build() { return m_builder.to_byte_string(); }
 
-    static DeprecatedString from(Markdown::Heading const& heading)
+    static ByteString from(Markdown::Heading const& heading)
     {
         StringCollector collector;
         heading.walk(collector);
         return collector.build();
     }
 
-    static DeprecatedString from(Markdown::Text::Node const& node)
+    static ByteString from(Markdown::Text::Node const& node)
     {
         StringCollector collector;
         node.walk(collector);
@@ -133,7 +133,7 @@ public:
     }
 
 private:
-    virtual RecursionDecision visit(DeprecatedString const& text) override
+    virtual RecursionDecision visit(ByteString const& text) override
     {
         m_builder.append(text);
         return RecursionDecision::Recurse;
@@ -142,10 +142,10 @@ private:
     StringBuilder m_builder;
 };
 
-static DeprecatedString slugify(DeprecatedString const& text)
+static ByteString slugify(ByteString const& text)
 {
     // TODO: This feels like it belongs into LibWeb.
-    DeprecatedString slug = text.to_lowercase();
+    ByteString slug = text.to_lowercase();
     // Reverse-engineered through github, using:
     // find AK/ Base/ Documentation/ Kernel/ Meta/ Ports/ Tests/ Userland/ -name '*.md' | xargs grep --color=always -Pin '^##+ .*[^a-z0-9 ?()`_:/!&|.$'"'"',<>"+-]' README.md
     slug = slug.replace(" "sv, "-"sv, ReplaceMode::All)
@@ -178,7 +178,7 @@ RecursionDecision MarkdownLinkage::visit(Markdown::Heading const& heading)
 
 RecursionDecision MarkdownLinkage::visit(Markdown::Text::LinkNode const& link_node)
 {
-    DeprecatedString const& href = link_node.href;
+    ByteString const& href = link_node.href;
     if (href.is_empty()) {
         // Nothing to do here.
         return RecursionDecision::Recurse;
@@ -204,9 +204,9 @@ RecursionDecision MarkdownLinkage::visit(Markdown::Text::LinkNode const& link_no
             }
 
             // Remove leading '/' from the path.
-            auto file = DeprecatedString::formatted("{}/Base/usr/share/man/man{}.md", m_serenity_source_directory, url.serialize_path().substring(1));
+            auto file = ByteString::formatted("{}/Base/usr/share/man/man{}.md", m_serenity_source_directory, url.serialize_path().substring(1));
 
-            m_file_links.append({ file, DeprecatedString(), StringCollector::from(*link_node.text) });
+            m_file_links.append({ file, ByteString(), StringCollector::from(*link_node.text) });
             return RecursionDecision::Recurse;
         }
         if (url.scheme() == "file") {
@@ -218,8 +218,8 @@ RecursionDecision MarkdownLinkage::visit(Markdown::Text::LinkNode const& link_no
             }
             // TODO: Check more possible links other than icons.
             if (file_path.starts_with("/res/icons/"sv)) {
-                auto file = DeprecatedString::formatted("{}/Base{}", m_serenity_source_directory, file_path);
-                m_file_links.append({ file, DeprecatedString(), StringCollector::from(*link_node.text) });
+                auto file = ByteString::formatted("{}/Base{}", m_serenity_source_directory, file_path);
+                m_file_links.append({ file, ByteString(), StringCollector::from(*link_node.text) });
             } else if (file_path.starts_with("/bin"sv)) {
                 StringBuilder builder;
                 link_node.text->render_to_html(builder);
@@ -235,12 +235,12 @@ RecursionDecision MarkdownLinkage::visit(Markdown::Text::LinkNode const& link_no
         }
     }
 
-    DeprecatedString label = StringCollector::from(*link_node.text);
+    ByteString label = StringCollector::from(*link_node.text);
     Optional<size_t> last_hash = href.find_last('#');
     if (last_hash.has_value()) {
         m_file_links.append({ href.substring(0, last_hash.value()), href.substring(last_hash.value() + 1), label });
     } else {
-        m_file_links.append({ href, DeprecatedString(), label });
+        m_file_links.append({ href, ByteString(), label });
     }
 
     return RecursionDecision::Recurse;
@@ -339,14 +339,14 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             continue;
         }
 
-        auto file_lexical_path = LexicalPath(file_item.key.to_deprecated_string());
+        auto file_lexical_path = LexicalPath(file_item.key.to_byte_string());
         auto file_dir = file_lexical_path.dirname();
         for (auto const& file_link : file_item.value.file_links()) {
             String pointee_file;
             if (file_link.file_path.is_empty()) {
                 pointee_file = file_item.key;
             } else {
-                pointee_file = TRY(String::from_deprecated_string(LexicalPath::absolute_path(file_dir, file_link.file_path)));
+                pointee_file = TRY(String::from_byte_string(LexicalPath::absolute_path(file_dir, file_link.file_path)));
             }
             if (!FileSystem::exists(pointee_file) && !is_missing_file_acceptable(pointee_file)) {
                 outln("File '{}' points to '{}' (label '{}'), but '{}' does not exist!",
@@ -404,7 +404,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                     dbgln("Not including {} in the link graph since it's not a man page.", link.file_path);
                     continue;
                 }
-                TRY(pages.try_set(TRY(String::from_deprecated_string(link.file_path)), maybe_target_page.value()));
+                TRY(pages.try_set(TRY(String::from_byte_string(link.file_path)), maybe_target_page.value()));
             }
         }
 
@@ -416,7 +416,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
             Vector<NonnullRefPtr<Manual::PageNode const>> linked_pages;
             for (auto const& link : file.value.file_links()) {
-                auto linked_page = pages.get(TRY(String::from_deprecated_string(link.file_path)));
+                auto linked_page = pages.get(TRY(String::from_byte_string(link.file_path)));
                 if (!linked_page.has_value())
                     continue;
 
diff --git a/Userland/Utilities/matroska.cpp b/Userland/Utilities/matroska.cpp
index a79cac79f92..611cfb9af07 100644
--- a/Userland/Utilities/matroska.cpp
+++ b/Userland/Utilities/matroska.cpp
@@ -42,8 +42,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     outln("DocTypeVersion is {}", reader.header().doc_type_version);
     auto segment_information = TRY_PARSE(reader.segment_information());
     outln("Timestamp scale is {}", segment_information.timestamp_scale());
-    outln("Muxing app is \"{}\"", segment_information.muxing_app().as_string().to_deprecated_string().characters());
-    outln("Writing app is \"{}\"", segment_information.writing_app().as_string().to_deprecated_string().characters());
+    outln("Muxing app is \"{}\"", segment_information.muxing_app().as_string().to_byte_string().characters());
+    outln("Writing app is \"{}\"", segment_information.writing_app().as_string().to_byte_string().characters());
 
     outln("Document has {} tracks", TRY_PARSE(reader.track_count()));
     TRY_PARSE(reader.for_each_track([&](Video::Matroska::TrackEntry const& track_entry) -> Video::DecoderErrorOr<IterationDecision> {
diff --git a/Userland/Utilities/md.cpp b/Userland/Utilities/md.cpp
index 16a2c25d133..96ff3018fcc 100644
--- a/Userland/Utilities/md.cpp
+++ b/Userland/Utilities/md.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/File.h>
 #include <LibCore/System.h>
@@ -48,7 +48,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto buffer = TRY(file->read_until_eof());
     dbgln("Read size {}", buffer.size());
 
-    auto input = DeprecatedString::copy(buffer);
+    auto input = ByteString::copy(buffer);
     auto document = Markdown::Document::parse(input);
 
     if (!document) {
diff --git a/Userland/Utilities/mkfifo.cpp b/Userland/Utilities/mkfifo.cpp
index 35e7a489389..c6e349e7607 100644
--- a/Userland/Utilities/mkfifo.cpp
+++ b/Userland/Utilities/mkfifo.cpp
@@ -14,7 +14,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio dpath"));
 
-    DeprecatedString mode_string;
+    ByteString mode_string;
     mode_t mask_reference_mode = 0777;
     mode_t mode = 0666;
     Vector<StringView> paths;
diff --git a/Userland/Utilities/mktemp.cpp b/Userland/Utilities/mktemp.cpp
index e9e50b1d20e..cf64e6fd585 100644
--- a/Userland/Utilities/mktemp.cpp
+++ b/Userland/Utilities/mktemp.cpp
@@ -15,7 +15,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
-static DeprecatedString generate_random_filename(DeprecatedString const& pattern)
+static ByteString generate_random_filename(ByteString const& pattern)
 {
     StringBuilder new_filename { pattern.length() };
 
@@ -27,10 +27,10 @@ static DeprecatedString generate_random_filename(DeprecatedString const& pattern
             new_filename.append(pattern[i]);
     }
 
-    return new_filename.to_deprecated_string();
+    return new_filename.to_byte_string();
 }
 
-static ErrorOr<Optional<DeprecatedString>> make_temp(DeprecatedString const& pattern, bool directory, bool dry_run)
+static ErrorOr<Optional<ByteString>> make_temp(ByteString const& pattern, bool directory, bool dry_run)
 {
     for (int i = 0; i < 100; ++i) {
         auto path = generate_random_filename(pattern);
@@ -76,7 +76,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     if (target_directory.is_empty()) {
         if (!file_template.is_empty()) {
-            auto resolved_path = LexicalPath(TRY(FileSystem::absolute_path(file_template)).to_deprecated_string());
+            auto resolved_path = LexicalPath(TRY(FileSystem::absolute_path(file_template)).to_byte_string());
             final_target_directory = TRY(String::from_utf8(resolved_path.dirname()));
             final_file_template = TRY(String::from_utf8(resolved_path.basename()));
         } else {
@@ -97,7 +97,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return 1;
     }
 
-    auto target_path = LexicalPath::join(final_target_directory->to_deprecated_string(), final_file_template->to_deprecated_string()).string();
+    auto target_path = LexicalPath::join(final_target_directory->to_byte_string(), final_file_template->to_byte_string()).string();
 
     auto final_path = TRY(make_temp(target_path, create_directory, dry_run));
     if (!final_path.has_value()) {
diff --git a/Userland/Utilities/mount.cpp b/Userland/Utilities/mount.cpp
index 28f77520777..dca6e692553 100644
--- a/Userland/Utilities/mount.cpp
+++ b/Userland/Utilities/mount.cpp
@@ -63,13 +63,13 @@ static ErrorOr<int> get_source_fd(StringView source)
     return fd_or_error;
 }
 
-static bool mount_by_line(DeprecatedString const& line)
+static bool mount_by_line(ByteString const& line)
 {
     // Skip comments and blank lines.
     if (line.is_empty() || line.starts_with('#'))
         return true;
 
-    Vector<DeprecatedString> parts = line.split('\t');
+    Vector<ByteString> parts = line.split('\t');
     if (parts.size() < 3) {
         warnln("Invalid fstab entry: {}", line);
         return false;
@@ -163,9 +163,9 @@ static ErrorOr<void> print_mounts()
 
     json.as_array().for_each([](auto& value) {
         auto& fs_object = value.as_object();
-        auto class_name = fs_object.get_deprecated_string("class_name"sv).value_or({});
-        auto mount_point = fs_object.get_deprecated_string("mount_point"sv).value_or({});
-        auto source = fs_object.get_deprecated_string("source"sv).value_or("none");
+        auto class_name = fs_object.get_byte_string("class_name"sv).value_or({});
+        auto mount_point = fs_object.get_byte_string("mount_point"sv).value_or({});
+        auto source = fs_object.get_byte_string("source"sv).value_or("none");
         auto readonly = fs_object.get_bool("readonly"sv).value_or(false);
         auto mount_flags = fs_object.get_u32("mount_flags"sv).value_or(0);
 
diff --git a/Userland/Utilities/mv.cpp b/Userland/Utilities/mv.cpp
index 89e7d281c92..aabcd3d5afa 100644
--- a/Userland/Utilities/mv.cpp
+++ b/Userland/Utilities/mv.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/System.h>
@@ -23,7 +23,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     bool no_clobber = false;
     bool verbose = false;
 
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(force, "Force", "force", 'f');
@@ -61,11 +61,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     umask(my_umask);
 
     for (auto& old_path : paths) {
-        DeprecatedString combined_new_path;
+        ByteString combined_new_path;
         auto new_path = original_new_path;
         if (S_ISDIR(st.st_mode)) {
             auto old_basename = LexicalPath::basename(old_path);
-            combined_new_path = DeprecatedString::formatted("{}/{}", original_new_path, old_basename);
+            combined_new_path = ByteString::formatted("{}/{}", original_new_path, old_basename);
             new_path = combined_new_path.characters();
         }
 
diff --git a/Userland/Utilities/nc.cpp b/Userland/Utilities/nc.cpp
index fd26bcfb938..82bd44239d9 100644
--- a/Userland/Utilities/nc.cpp
+++ b/Userland/Utilities/nc.cpp
@@ -51,7 +51,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     bool should_close = false;
     bool udp_mode = false;
     bool numeric_mode = false;
-    DeprecatedString target;
+    ByteString target;
     u16 port = 0;
     u16 local_port = 0;
     int maximum_tcp_receive_buffer_size_input = -1;
diff --git a/Userland/Utilities/netstat.cpp b/Userland/Utilities/netstat.cpp
index 3133e73799e..c7b1c0a46b0 100644
--- a/Userland/Utilities/netstat.cpp
+++ b/Userland/Utilities/netstat.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/IPv4Address.h>
 #include <AK/JsonArray.h>
@@ -59,7 +59,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     uid_t current_uid = getuid();
 
-    HashMap<pid_t, DeprecatedString> programs;
+    HashMap<pid_t, ByteString> programs;
 
     if (flag_program) {
         auto processes = TRY(Core::ProcessStatisticsReader::get_all());
@@ -75,10 +75,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     };
 
     struct Column {
-        DeprecatedString title;
+        ByteString title;
         Alignment alignment { Alignment::Left };
         int width { 0 };
-        DeprecatedString buffer;
+        ByteString buffer;
     };
 
     Vector<Column> columns;
@@ -118,22 +118,22 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         }
     };
 
-    auto get_formatted_address = [&](DeprecatedString const& address, String const& port) {
+    auto get_formatted_address = [&](ByteString const& address, String const& port) {
         if (flag_wide)
-            return DeprecatedString::formatted("{}:{}", address, port);
+            return ByteString::formatted("{}:{}", address, port);
 
         if ((address.length() + port.bytes().size()) <= max_formatted_address_length)
-            return DeprecatedString::formatted("{}:{}", address, port);
+            return ByteString::formatted("{}:{}", address, port);
 
-        return DeprecatedString::formatted("{}:{}", address.substring_view(0, max_formatted_address_length - port.bytes().size()), port);
+        return ByteString::formatted("{}:{}", address.substring_view(0, max_formatted_address_length - port.bytes().size()), port);
     };
 
     auto get_formatted_program = [&](pid_t pid) {
         if (pid == -1)
-            return DeprecatedString("-");
+            return ByteString("-");
 
         auto program = programs.get(pid);
-        return DeprecatedString::formatted("{}/{}", pid, program.value());
+        return ByteString::formatted("{}/{}", pid, program.value());
     };
 
     auto get_formatted_user = [&](i32 uid) -> ErrorOr<String> {
@@ -185,7 +185,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             auto bytes_in = if_object.get_u32("bytes_in"sv).value_or({});
             auto bytes_out = if_object.get_u32("bytes_out"sv).value_or({});
 
-            auto peer_address = if_object.get_deprecated_string("peer_address"sv).value_or({});
+            auto peer_address = if_object.get_byte_string("peer_address"sv).value_or({});
             if (!flag_numeric) {
                 auto from_string = IPv4Address::from_string(peer_address);
                 auto addr = from_string.value().to_in_addr_t();
@@ -207,7 +207,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 }
             }
 
-            auto local_address = if_object.get_deprecated_string("local_address"sv).value_or({});
+            auto local_address = if_object.get_byte_string("local_address"sv).value_or({});
             if (!flag_numeric) {
                 auto from_string = IPv4Address::from_string(local_address);
                 auto addr = from_string.value().to_in_addr_t();
@@ -229,7 +229,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 }
             }
 
-            auto state = if_object.get_deprecated_string("state"sv).value_or({});
+            auto state = if_object.get_byte_string("state"sv).value_or({});
             auto origin_uid = if_object.get_i32("origin_uid"sv).value_or(-1);
             auto origin_pid = if_object.get_i32("origin_pid"sv).value_or(-1);
 
@@ -239,9 +239,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             if (protocol_column != -1)
                 columns[protocol_column].buffer = "tcp";
             if (bytes_in_column != -1)
-                columns[bytes_in_column].buffer = TRY(String::number(bytes_in)).to_deprecated_string();
+                columns[bytes_in_column].buffer = TRY(String::number(bytes_in)).to_byte_string();
             if (bytes_out_column != -1)
-                columns[bytes_out_column].buffer = TRY(String::number(bytes_out)).to_deprecated_string();
+                columns[bytes_out_column].buffer = TRY(String::number(bytes_out)).to_byte_string();
             if (local_address_column != -1)
                 columns[local_address_column].buffer = get_formatted_address(local_address, local_port);
             if (peer_address_column != -1)
@@ -249,7 +249,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             if (state_column != -1)
                 columns[state_column].buffer = state;
             if (flag_extend && user_column != -1)
-                columns[user_column].buffer = TRY(get_formatted_user(origin_uid)).to_deprecated_string();
+                columns[user_column].buffer = TRY(get_formatted_user(origin_uid)).to_byte_string();
             if (flag_program && program_column != -1)
                 columns[program_column].buffer = get_formatted_program(origin_pid);
 
@@ -272,7 +272,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         for (auto& value : sorted_regions) {
             auto& if_object = value.as_object();
 
-            auto local_address = if_object.get_deprecated_string("local_address"sv).value_or({});
+            auto local_address = if_object.get_byte_string("local_address"sv).value_or({});
             if (!flag_numeric) {
                 auto from_string = IPv4Address::from_string(local_address);
                 auto addr = from_string.value().to_in_addr_t();
@@ -294,7 +294,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 }
             }
 
-            auto peer_address = if_object.get_deprecated_string("peer_address"sv).value_or({});
+            auto peer_address = if_object.get_byte_string("peer_address"sv).value_or({});
             if (!flag_numeric) {
                 auto from_string = IPv4Address::from_string(peer_address);
                 auto addr = from_string.value().to_in_addr_t();
@@ -332,7 +332,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             if (state_column != -1)
                 columns[state_column].buffer = "-";
             if (flag_extend && user_column != -1)
-                columns[user_column].buffer = TRY(get_formatted_user(origin_uid)).to_deprecated_string();
+                columns[user_column].buffer = TRY(get_formatted_user(origin_uid)).to_byte_string();
             if (flag_program && program_column != -1)
                 columns[program_column].buffer = get_formatted_program(origin_pid);
 
diff --git a/Userland/Utilities/network-settings.cpp b/Userland/Utilities/network-settings.cpp
index 916423e4984..0d546a49dfc 100644
--- a/Userland/Utilities/network-settings.cpp
+++ b/Userland/Utilities/network-settings.cpp
@@ -35,8 +35,8 @@ ErrorOr<int> serenity_main(Main::Arguments)
     auto json_object = json.as_object();
 
     auto config_file = TRY(Core::ConfigFile::open_for_system("Network", Core::ConfigFile::AllowWriting::Yes));
-    json_object.for_each_member([&](DeprecatedString const& adapter_name, JsonValue const& adapter_data) {
-        adapter_data.as_object().for_each_member([&](const DeprecatedString& key, const JsonValue& value) {
+    json_object.for_each_member([&](ByteString const& adapter_name, JsonValue const& adapter_data) {
+        adapter_data.as_object().for_each_member([&](const ByteString& key, const JsonValue& value) {
             switch (value.type()) {
             case JsonValue::Type::String:
                 config_file->write_entry(adapter_name, key, value.as_string());
diff --git a/Userland/Utilities/nl.cpp b/Userland/Utilities/nl.cpp
index 9d38882bd2d..5956b828cce 100644
--- a/Userland/Utilities/nl.cpp
+++ b/Userland/Utilities/nl.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Vector.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/File.h>
diff --git a/Userland/Utilities/nohup.cpp b/Userland/Utilities/nohup.cpp
index 45eea5e385e..6fa4ea55f48 100644
--- a/Userland/Utilities/nohup.cpp
+++ b/Userland/Utilities/nohup.cpp
@@ -16,7 +16,7 @@ namespace {
 void dup_out_file(int fd_to_redirect)
 {
     int fd = -1;
-    DeprecatedString path = "nohup.out";
+    ByteString path = "nohup.out";
     auto options = O_CREAT | O_WRONLY | O_APPEND;
     auto mode = S_IRUSR | S_IWUSR;
     auto fd_or_error = Core::System::open(path, options, mode);
diff --git a/Userland/Utilities/ntpquery.cpp b/Userland/Utilities/ntpquery.cpp
index 444fdf9a3cd..084bfc30be5 100644
--- a/Userland/Utilities/ntpquery.cpp
+++ b/Userland/Utilities/ntpquery.cpp
@@ -76,7 +76,7 @@ static timeval timeval_from_ntp_timestamp(NtpTimestamp const& ntp_timestamp)
     return t;
 }
 
-static DeprecatedString format_ntp_timestamp(NtpTimestamp ntp_timestamp)
+static ByteString format_ntp_timestamp(NtpTimestamp ntp_timestamp)
 {
     char buffer[28]; // YYYY-MM-DDTHH:MM:SS.UUUUUUZ is 27 characters long.
     timeval t = timeval_from_ntp_timestamp(ntp_timestamp);
@@ -107,7 +107,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     // Leap seconds smearing NTP servers:
     // - time.facebook.com , https://engineering.fb.com/production-engineering/ntp-service/ , sine-smears over 18 hours
     // - time.google.com , https://developers.google.com/time/smear , linear-smears over 24 hours
-    DeprecatedString host = "time.google.com"sv;
+    ByteString host = "time.google.com"sv;
     Core::ArgsParser args_parser;
     args_parser.add_option(adjust_time, "Gradually adjust system time (requires root)", "adjust", 'a');
     args_parser.add_option(set_time, "Immediately set system time (requires root)", "set", 's');
diff --git a/Userland/Utilities/open.cpp b/Userland/Utilities/open.cpp
index 4ba569830ca..5eb25e73a4d 100644
--- a/Userland/Utilities/open.cpp
+++ b/Userland/Utilities/open.cpp
@@ -34,7 +34,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 continue;
             }
         } else {
-            url = URL::create_with_url_or_path(path_or_error.value().to_deprecated_string());
+            url = URL::create_with_url_or_path(path_or_error.value().to_byte_string());
         }
 
         if (!Desktop::Launcher::open(url)) {
diff --git a/Userland/Utilities/paste.cpp b/Userland/Utilities/paste.cpp
index 1ee43cee473..58eef8c282b 100644
--- a/Userland/Utilities/paste.cpp
+++ b/Userland/Utilities/paste.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/System.h>
@@ -69,7 +69,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     if (watch) {
         watch_command.append({});
 
-        clipboard.on_change = [&](DeprecatedString const&) {
+        clipboard.on_change = [&](ByteString const&) {
             // Technically there's a race here...
             auto data_and_type = clipboard.fetch_data_and_type();
             if (data_and_type.mime_type.is_empty()) {
diff --git a/Userland/Utilities/pathchk.cpp b/Userland/Utilities/pathchk.cpp
index 973fe3e2bae..c2ef0c41e5c 100644
--- a/Userland/Utilities/pathchk.cpp
+++ b/Userland/Utilities/pathchk.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/System.h>
 #include <LibMain/Main.h>
@@ -18,7 +18,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     static bool flag_most_posix = false;
     static bool flag_portability = false;
     static bool flag_empty_name_and_leading_dash = false;
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(flag_most_posix, "Check for most POSIX systems", nullptr, 'p');
diff --git a/Userland/Utilities/pdf.cpp b/Userland/Utilities/pdf.cpp
index 13345665498..74c312e7e0c 100644
--- a/Userland/Utilities/pdf.cpp
+++ b/Userland/Utilities/pdf.cpp
@@ -119,7 +119,7 @@ static ErrorOr<String> summary_string(Vector<int> const& pages)
 
 static PDF::PDFErrorOr<void> print_debugging_stats(PDF::Document& document, bool json)
 {
-    HashMap<DeprecatedString, Vector<int>> diags_to_pages;
+    HashMap<ByteString, Vector<int>> diags_to_pages;
     for (u32 page_number = 1; page_number <= document.get_page_count(); ++page_number) {
         if (!json) {
             out("page number {} / {}", page_number, document.get_page_count());
@@ -165,7 +165,7 @@ static PDF::PDFErrorOr<void> print_debugging_stats(PDF::Document& document, bool
     }
     if (json) {
         json_output.set("issues", issues);
-        outln("{}", json_output.to_deprecated_string());
+        outln("{}", json_output.to_byte_string());
     }
     return {};
 }
diff --git a/Userland/Utilities/pidof.cpp b/Userland/Utilities/pidof.cpp
index 6b61b8f15d3..57745a08873 100644
--- a/Userland/Utilities/pidof.cpp
+++ b/Userland/Utilities/pidof.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/ProcessStatisticsReader.h>
 #include <LibCore/System.h>
diff --git a/Userland/Utilities/ping.cpp b/Userland/Utilities/ping.cpp
index e42b29dee16..17278f629e7 100644
--- a/Userland/Utilities/ping.cpp
+++ b/Userland/Utilities/ping.cpp
@@ -30,7 +30,7 @@ static Optional<size_t> count;
 static uint32_t total_ms;
 static int min_ms;
 static int max_ms;
-static DeprecatedString host;
+static ByteString host;
 static int payload_size = -1;
 static bool quiet = false;
 static Optional<size_t> ttl;
diff --git a/Userland/Utilities/pixelflut.cpp b/Userland/Utilities/pixelflut.cpp
index dd5fa69d11e..a124de0fbb7 100644
--- a/Userland/Utilities/pixelflut.cpp
+++ b/Userland/Utilities/pixelflut.cpp
@@ -50,7 +50,7 @@ ErrorOr<NonnullRefPtr<Client>> Client::create(StringView image_path, StringView
     auto port = maybe_port.release_value();
     auto hostname = TRY(String::join(':', parts));
 
-    auto socket = TRY(Core::BufferedTCPSocket::create(TRY(Core::TCPSocket::connect(hostname.to_deprecated_string(), port))));
+    auto socket = TRY(Core::BufferedTCPSocket::create(TRY(Core::TCPSocket::connect(hostname.to_byte_string(), port))));
 
     // Ask the server for the canvas size.
     TRY(socket->write_until_depleted(get_command.bytes()));
@@ -113,7 +113,7 @@ ErrorOr<void> Client::send_current_pixel()
     auto color = m_image->get_pixel(m_current_point);
     if (color.alpha() == 0)
         return {};
-    auto hex = color.to_deprecated_string();
+    auto hex = color.to_byte_string();
     // Pixelflut requires hex colors without leading hash.
     auto hex_without_hash = hex.substring(1);
 
diff --git a/Userland/Utilities/pkg/AvailablePort.cpp b/Userland/Utilities/pkg/AvailablePort.cpp
index 8e47d6eecbc..4acb4e1919a 100644
--- a/Userland/Utilities/pkg/AvailablePort.cpp
+++ b/Userland/Utilities/pkg/AvailablePort.cpp
@@ -84,14 +84,14 @@ ErrorOr<int> AvailablePort::update_available_ports_list_file()
     }
     RefPtr<Protocol::Request> request;
     auto protocol_client = TRY(Protocol::RequestClient::try_create());
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> request_headers;
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> request_headers;
     Core::ProxyData proxy_data {};
 
     auto output_stream = TRY(Core::File::open("/usr/Ports/AvailablePorts.md"sv, Core::File::OpenMode::ReadWrite, 0644));
     Core::EventLoop loop;
 
     URL url("https://raw.githubusercontent.com/SerenityOS/serenity/master/Ports/AvailablePorts.md");
-    DeprecatedString method = "GET";
+    ByteString method = "GET";
     outln("pkg: Syncing packages database...");
     request = protocol_client->start_request(method, url, request_headers, ReadonlyBytes {}, proxy_data);
     request->on_finish = [&](bool success, auto) {
@@ -161,11 +161,11 @@ ErrorOr<HashMap<String, AvailablePort>> AvailablePort::read_available_ports_list
     HashMap<String, AvailablePort> available_ports;
     for (size_t port_index = 0; port_index < port_name_column.rows.size(); port_index++) {
         auto name = TRY(extract_port_name_from_column(port_name_column, port_index));
-        auto website = TRY(String::from_deprecated_string(port_website_column.rows[port_index].render_for_terminal()));
+        auto website = TRY(String::from_byte_string(port_website_column.rows[port_index].render_for_terminal()));
         if (website.is_empty())
             website = "n/a"_string;
 
-        auto version = TRY(String::from_deprecated_string(port_version_column.rows[port_index].render_for_terminal()));
+        auto version = TRY(String::from_byte_string(port_version_column.rows[port_index].render_for_terminal()));
         if (version.is_empty())
             version = "n/a"_string;
 
diff --git a/Userland/Utilities/pledge.cpp b/Userland/Utilities/pledge.cpp
index 4d852f1928f..6cb5e2270e2 100644
--- a/Userland/Utilities/pledge.cpp
+++ b/Userland/Utilities/pledge.cpp
@@ -21,7 +21,7 @@ static ErrorOr<bool> is_dynamically_linked_executable(StringView filename)
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
-    DeprecatedString promises;
+    ByteString promises;
     Vector<StringView> command;
     bool add_promises_for_dynamic_linker;
 
@@ -35,7 +35,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         auto constexpr loader_promises = "stdio rpath prot_exec"sv;
         MUST(Core::System::setenv("_LOADER_PLEDGE_PROMISES"sv, loader_promises, true));
         MUST(Core::System::setenv("_LOADER_MAIN_PROGRAM_PLEDGE_PROMISES"sv, promises, true));
-        promises = DeprecatedString::formatted("{} {}", promises, loader_promises);
+        promises = ByteString::formatted("{} {}", promises, loader_promises);
     }
 
     TRY(Core::System::pledge(StringView(), promises));
diff --git a/Userland/Utilities/pmap.cpp b/Userland/Utilities/pmap.cpp
index 5c33a6eb2b7..522bf18d520 100644
--- a/Userland/Utilities/pmap.cpp
+++ b/Userland/Utilities/pmap.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/JsonObject.h>
 #include <AK/QuickSort.h>
 #include <LibCore/ArgsParser.h>
@@ -26,7 +26,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.add_positional_argument(pid, "PID", "PID", Core::ArgsParser::Required::Yes);
     args_parser.parse(arguments);
 
-    auto file = TRY(Core::File::open(DeprecatedString::formatted("/proc/{}/vm", pid), Core::File::OpenMode::Read));
+    auto file = TRY(Core::File::open(ByteString::formatted("/proc/{}/vm", pid), Core::File::OpenMode::Read));
 
     outln("{}:", pid);
 
@@ -49,9 +49,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     for (auto& value : sorted_regions) {
         auto& map = value.as_object();
         auto address = map.get_addr("address"sv).value_or(0);
-        auto size = map.get("size"sv).value_or({}).to_deprecated_string();
+        auto size = map.get("size"sv).value_or({}).to_byte_string();
 
-        auto access = DeprecatedString::formatted("{}{}{}{}{}",
+        auto access = ByteString::formatted("{}{}{}{}{}",
             (map.get_bool("readable"sv).value_or(false) ? "r" : "-"),
             (map.get_bool("writable"sv).value_or(false) ? "w" : "-"),
             (map.get_bool("executable"sv).value_or(false) ? "x" : "-"),
@@ -61,13 +61,13 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         out("{:p}  ", address);
         out("{:>10} ", size);
         if (extended) {
-            auto resident = map.get("amount_resident"sv).value_or({}).to_deprecated_string();
-            auto dirty = map.get("amount_dirty"sv).value_or({}).to_deprecated_string();
-            auto vmobject = map.get_deprecated_string("vmobject"sv).value_or({});
+            auto resident = map.get("amount_resident"sv).value_or({}).to_byte_string();
+            auto dirty = map.get("amount_dirty"sv).value_or({}).to_byte_string();
+            auto vmobject = map.get_byte_string("vmobject"sv).value_or({});
             if (vmobject.ends_with("VMObject"sv))
                 vmobject = vmobject.substring(0, vmobject.length() - 8);
-            auto purgeable = map.get("purgeable"sv).value_or({}).to_deprecated_string();
-            auto cow_pages = map.get("cow_pages"sv).value_or({}).to_deprecated_string();
+            auto purgeable = map.get("purgeable"sv).value_or({}).to_byte_string();
+            auto cow_pages = map.get("cow_pages"sv).value_or({}).to_byte_string();
             out("{:>10} ", resident);
             out("{:>10} ", dirty);
             out("{:6} ", access);
@@ -77,7 +77,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         } else {
             out("{:6} ", access);
         }
-        auto name = map.get_deprecated_string("name"sv).value_or({});
+        auto name = map.get_byte_string("name"sv).value_or({});
         out("{:20}", name);
         outln();
     }
diff --git a/Userland/Utilities/pmemdump.cpp b/Userland/Utilities/pmemdump.cpp
index 77293db453e..a8edc3d7119 100644
--- a/Userland/Utilities/pmemdump.cpp
+++ b/Userland/Utilities/pmemdump.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringUtils.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/System.h>
@@ -19,7 +19,7 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
-static bool try_set_offset_and_length_parameters(DeprecatedString const& arg_offset, DeprecatedString const& arg_length, u64& offset, u64& length)
+static bool try_set_offset_and_length_parameters(ByteString const& arg_offset, ByteString const& arg_length, u64& offset, u64& length)
 {
     // TODO: Add support for hex values
     auto possible_offset = arg_offset.to_uint<u64>();
diff --git a/Userland/Utilities/printf.cpp b/Userland/Utilities/printf.cpp
index 8051465e127..784d0030c66 100644
--- a/Userland/Utilities/printf.cpp
+++ b/Userland/Utilities/printf.cpp
@@ -5,7 +5,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/PrintfImplementation.h>
 #include <AK/StringBuilder.h>
 #include <AK/Types.h>
@@ -234,7 +234,7 @@ struct ArgvWithCount {
     int& argc;
 };
 
-static DeprecatedString handle_escapes(char const* string)
+static ByteString handle_escapes(char const* string)
 {
     StringBuilder builder;
     for (auto c = *string; c; c = *++string) {
@@ -252,7 +252,7 @@ static DeprecatedString handle_escapes(char const* string)
                     builder.append('\b');
                     break;
                 case 'c':
-                    return builder.to_deprecated_string();
+                    return builder.to_byte_string();
                 case 'e':
                     builder.append('\e');
                     break;
@@ -288,7 +288,7 @@ static DeprecatedString handle_escapes(char const* string)
         }
     }
 
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
@@ -300,7 +300,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto argv = arguments.argv;
 
     ++argv;
-    DeprecatedString format = handle_escapes(*(argv++));
+    ByteString format = handle_escapes(*(argv++));
     auto format_string = format.characters();
 
     argc -= 2;
diff --git a/Userland/Utilities/pro.cpp b/Userland/Utilities/pro.cpp
index 41b4719172f..a949fc22f67 100644
--- a/Userland/Utilities/pro.cpp
+++ b/Userland/Utilities/pro.cpp
@@ -154,9 +154,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     bool verbose_output = false;
     StringView data;
     StringView proxy_spec;
-    DeprecatedString method = "GET";
+    ByteString method = "GET";
     StringView method_override;
-    HashMap<DeprecatedString, DeprecatedString, CaseInsensitiveStringTraits> request_headers;
+    HashMap<ByteString, ByteString, CaseInsensitiveStringTraits> request_headers;
     String credentials;
 
     Core::ArgsParser args_parser;
@@ -253,7 +253,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         // that scheme as (...) or a single sequence of characters capable of holding base64-encoded information.
         auto const encoded_credentials = TRY(encode_base64(credentials.bytes()));
         auto const authorization = TRY(String::formatted("Basic {}", encoded_credentials));
-        request_headers.set("Authorization", authorization.to_deprecated_string());
+        request_headers.set("Authorization", authorization.to_byte_string());
     } else {
         if (is_http_url && has_credentials && has_manual_authorization_header)
             warnln("* Skipping encoding provided authorization, manual header present.");
@@ -326,7 +326,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             }
 
             if (!following_url && save_at_provided_name) {
-                DeprecatedString output_name;
+                ByteString output_name;
                 if (auto content_disposition = response_headers.get("Content-Disposition"); content_disposition.has_value()) {
                     auto& value = content_disposition.value();
                     ContentDispositionParser parser(value);
@@ -343,9 +343,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 if (output_name.is_empty() || output_name == "/") {
                     int i = -1;
                     do {
-                        output_name = url.serialized_host().release_value_but_fixme_should_propagate_errors().to_deprecated_string();
+                        output_name = url.serialized_host().release_value_but_fixme_should_propagate_errors().to_byte_string();
                         if (i > -1)
-                            output_name = DeprecatedString::formatted("{}.{}", output_name, i);
+                            output_name = ByteString::formatted("{}.{}", output_name, i);
                         ++i;
                     } while (FileSystem::exists(output_name));
                 }
diff --git a/Userland/Utilities/profile.cpp b/Userland/Utilities/profile.cpp
index 0d168703905..a64f407bf3a 100644
--- a/Userland/Utilities/profile.cpp
+++ b/Userland/Utilities/profile.cpp
@@ -38,7 +38,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.add_option(Core::ArgsParser::Option {
         Core::ArgsParser::OptionArgumentMode::Required,
         "Enable tracking specific event type", nullptr, 't', "event_type",
-        [&](DeprecatedString event_type) {
+        [&](ByteString event_type) {
             seen_event_type_arg = true;
             if (event_type == "sample")
                 event_mask |= PERF_EVENT_SAMPLE;
diff --git a/Userland/Utilities/ps.cpp b/Userland/Utilities/ps.cpp
index 3cb38099e57..1502a98e085 100644
--- a/Userland/Utilities/ps.cpp
+++ b/Userland/Utilities/ps.cpp
@@ -85,7 +85,7 @@ static ErrorOr<String> column_to_string(ColumnId column_id, Core::ProcessStatist
 {
     switch (column_id) {
     case ColumnId::UserId:
-        return String::from_deprecated_string(process.username);
+        return String::from_byte_string(process.username);
     case ColumnId::ProcessId:
         return String::number(process.pid);
     case ColumnId::ParentProcessId:
@@ -95,11 +95,11 @@ static ErrorOr<String> column_to_string(ColumnId column_id, Core::ProcessStatist
     case ColumnId::SessionId:
         return String::number(process.sid);
     case ColumnId::TTY:
-        return process.tty == "" ? "n/a"_string : String::from_deprecated_string(process.tty);
+        return process.tty == "" ? "n/a"_string : String::from_byte_string(process.tty);
     case ColumnId::State:
         return process.threads.is_empty()
             ? "Zombie"_string
-            : String::from_deprecated_string(process.threads.first().state);
+            : String::from_byte_string(process.threads.first().state);
     case ColumnId::StartTime: {
         auto now = Core::DateTime::now();
         auto today_start = Core::DateTime::now();
@@ -110,7 +110,7 @@ static ErrorOr<String> column_to_string(ColumnId column_id, Core::ProcessStatist
         return process_creation_time.to_string("%b%d"sv);
     }
     case ColumnId::Command:
-        return String::from_deprecated_string(process.name);
+        return String::from_byte_string(process.name);
     default:
         VERIFY_NOT_REACHED();
     }
@@ -230,7 +230,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     Vector<Column> columns;
     Vector<pid_t> pid_list;
     Vector<pid_t> parent_pid_list;
-    Vector<DeprecatedString> tty_list;
+    Vector<ByteString> tty_list;
     Vector<uid_t> uid_list;
 
     Core::ArgsParser args_parser;
@@ -267,14 +267,14 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             warnln("Could not parse '{}' as a PID.", pid_string);
         return pid;
     }));
-    args_parser.add_option(make_list_option(tty_list, "Show processes associated with the given terminal. (Comma- or space-separated list.) The short TTY name or the full device path may be used.", "tty", 't', "tty-list", [&](StringView tty_string) -> Optional<DeprecatedString> {
+    args_parser.add_option(make_list_option(tty_list, "Show processes associated with the given terminal. (Comma- or space-separated list.) The short TTY name or the full device path may be used.", "tty", 't', "tty-list", [&](StringView tty_string) -> Optional<ByteString> {
         provided_filtering_option = true;
         auto tty_pseudo_name_or_error = parse_tty_pseudo_name(tty_string);
         if (tty_pseudo_name_or_error.is_error()) {
             warnln("Could not parse '{}' as a TTY", tty_string);
             return {};
         }
-        return tty_pseudo_name_or_error.release_value().to_deprecated_string();
+        return tty_pseudo_name_or_error.release_value().to_byte_string();
     }));
     args_parser.add_option(make_list_option(uid_list, "Show processes with a matching user ID or login name. (Comma- or space-separated list.)", nullptr, 'u', "user-list", [&](StringView user_string) -> Optional<uid_t> {
         provided_filtering_option = true;
diff --git a/Userland/Utilities/pwd.cpp b/Userland/Utilities/pwd.cpp
index 15c639df73f..f8e2276cab1 100644
--- a/Userland/Utilities/pwd.cpp
+++ b/Userland/Utilities/pwd.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <LibCore/System.h>
 #include <LibMain/Main.h>
diff --git a/Userland/Utilities/readelf.cpp b/Userland/Utilities/readelf.cpp
index 5565d1b60e9..29e58220231 100644
--- a/Userland/Utilities/readelf.cpp
+++ b/Userland/Utilities/readelf.cpp
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/LexicalPath.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringView.h>
@@ -206,7 +206,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio rpath map_fixed"));
 
-    DeprecatedString path {};
+    ByteString path {};
     static bool display_all = false;
     static bool display_elf_header = false;
     static bool display_program_headers = false;
@@ -432,17 +432,17 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 found_dynamic_section = true;
 
                 if (section.entry_count()) {
-                    outln("Dynamic section '{}' at offset {:#08x} contains {} entries.", section.name().to_deprecated_string(), section.offset(), section.entry_count());
+                    outln("Dynamic section '{}' at offset {:#08x} contains {} entries.", section.name().to_byte_string(), section.offset(), section.entry_count());
                 } else {
-                    outln("Dynamic section '{}' at offset {:#08x} contains zero entries.", section.name().to_deprecated_string(), section.offset());
+                    outln("Dynamic section '{}' at offset {:#08x} contains zero entries.", section.name().to_byte_string(), section.offset());
                 }
 
                 return IterationDecision::Break;
             });
 
-            Vector<DeprecatedString> libraries;
+            Vector<ByteString> libraries;
             object->for_each_needed_library([&libraries](StringView entry) {
-                libraries.append(DeprecatedString::formatted("{}", entry));
+                libraries.append(ByteString::formatted("{}", entry));
             });
 
             auto library_index = 0;
diff --git a/Userland/Utilities/reboot.cpp b/Userland/Utilities/reboot.cpp
index 3210d556b5c..3c2c58292f1 100644
--- a/Userland/Utilities/reboot.cpp
+++ b/Userland/Utilities/reboot.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/File.h>
 #include <LibMain/Main.h>
 
@@ -13,7 +13,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
 {
     auto file = TRY(Core::File::open("/sys/kernel/power_state"sv, Core::File::OpenMode::Write));
 
-    const DeprecatedString file_contents = "1";
+    const ByteString file_contents = "1";
     TRY(file->write_until_depleted(file_contents.bytes()));
     file->close();
 
diff --git a/Userland/Utilities/rev.cpp b/Userland/Utilities/rev.cpp
index 2611c222b05..9bd4366eb91 100644
--- a/Userland/Utilities/rev.cpp
+++ b/Userland/Utilities/rev.cpp
@@ -31,7 +31,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             if (path == "-") {
                 streams.append(stdin);
             } else {
-                FILE* stream = fopen(DeprecatedString(path).characters(), "r");
+                FILE* stream = fopen(ByteString(path).characters(), "r");
                 if (!stream) {
                     warnln("Failed to open {}: {}", path, strerror(errno));
                     continue;
@@ -70,7 +70,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 }
                 break;
             }
-            outln("{}", DeprecatedString { buffer, Chomp }.reverse());
+            outln("{}", ByteString { buffer, Chomp }.reverse());
         }
     }
 
diff --git a/Userland/Utilities/rmdir.cpp b/Userland/Utilities/rmdir.cpp
index f24aa7f13f4..e823ace5ebe 100644
--- a/Userland/Utilities/rmdir.cpp
+++ b/Userland/Utilities/rmdir.cpp
@@ -51,7 +51,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         for (size_t i = path_parts.size() - 1; i > 0; --i) {
             auto current_path_parts = path_parts.span().slice(0, i);
-            LexicalPath current_path { DeprecatedString::join('/', current_path_parts) };
+            LexicalPath current_path { ByteString::join('/', current_path_parts) };
             if (!remove_directory(current_path.string()))
                 break;
         }
diff --git a/Userland/Utilities/route.cpp b/Userland/Utilities/route.cpp
index 2c425cf6554..1c64ad46402 100644
--- a/Userland/Utilities/route.cpp
+++ b/Userland/Utilities/route.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/IPv4Address.h>
 #include <AK/JsonArray.h>
 #include <AK/JsonObject.h>
@@ -51,10 +51,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     };
 
     struct Column {
-        DeprecatedString title;
+        ByteString title;
         Alignment alignment { Alignment::Left };
         int width { 0 };
-        DeprecatedString buffer;
+        ByteString buffer;
     };
 
     Vector<Column> columns;
@@ -101,16 +101,16 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         Vector<JsonValue> sorted_regions = json.as_array().values();
         quick_sort(sorted_regions, [](auto& a, auto& b) {
-            return a.as_object().get_deprecated_string("destination"sv).value_or({}) < b.as_object().get_deprecated_string("destination"sv).value_or({});
+            return a.as_object().get_byte_string("destination"sv).value_or({}) < b.as_object().get_byte_string("destination"sv).value_or({});
         });
 
         for (auto& value : sorted_regions) {
             auto& if_object = value.as_object();
 
-            auto destination = if_object.get_deprecated_string("destination"sv).value_or({});
-            auto gateway = if_object.get_deprecated_string("gateway"sv).value_or({});
-            auto genmask = if_object.get_deprecated_string("genmask"sv).value_or({});
-            auto interface = if_object.get_deprecated_string("interface"sv).value_or({});
+            auto destination = if_object.get_byte_string("destination"sv).value_or({});
+            auto gateway = if_object.get_byte_string("gateway"sv).value_or({});
+            auto genmask = if_object.get_byte_string("genmask"sv).value_or({});
+            auto interface = if_object.get_byte_string("interface"sv).value_or({});
             auto flags = if_object.get_u32("flags"sv).value_or(0);
 
             StringBuilder flags_builder;
diff --git a/Userland/Utilities/run-tests.cpp b/Userland/Utilities/run-tests.cpp
index 06e5a6cea0f..b6727e449f6 100644
--- a/Userland/Utilities/run-tests.cpp
+++ b/Userland/Utilities/run-tests.cpp
@@ -33,11 +33,11 @@ struct FileResult {
     pid_t child_pid { 0 };
 };
 
-DeprecatedString g_currently_running_test;
+ByteString g_currently_running_test;
 
 class TestRunner : public ::Test::TestRunner {
 public:
-    TestRunner(DeprecatedString test_root, Regex<PosixExtended> exclude_regex, NonnullRefPtr<Core::ConfigFile> config, Regex<PosixExtended> skip_regex, bool run_skipped_tests, bool print_progress, bool print_json, bool print_all_output, bool unlink_coredumps, bool print_times = true)
+    TestRunner(ByteString test_root, Regex<PosixExtended> exclude_regex, NonnullRefPtr<Core::ConfigFile> config, Regex<PosixExtended> skip_regex, bool run_skipped_tests, bool print_progress, bool print_json, bool print_all_output, bool unlink_coredumps, bool print_times = true)
         : ::Test::TestRunner(move(test_root), print_times, print_progress, print_json)
         , m_exclude_regex(move(exclude_regex))
         , m_config(move(config))
@@ -55,29 +55,29 @@ public:
     virtual ~TestRunner() = default;
 
 protected:
-    virtual void do_run_single_test(DeprecatedString const& test_path, size_t current_text_index, size_t num_tests) override;
-    virtual Vector<DeprecatedString> get_test_paths() const override;
-    virtual Vector<DeprecatedString> const* get_failed_test_names() const override { return &m_failed_test_names; }
+    virtual void do_run_single_test(ByteString const& test_path, size_t current_text_index, size_t num_tests) override;
+    virtual Vector<ByteString> get_test_paths() const override;
+    virtual Vector<ByteString> const* get_failed_test_names() const override { return &m_failed_test_names; }
 
-    virtual FileResult run_test_file(DeprecatedString const& test_path);
+    virtual FileResult run_test_file(ByteString const& test_path);
 
     bool should_skip_test(LexicalPath const& test_path);
 
     Regex<PosixExtended> m_exclude_regex;
     NonnullRefPtr<Core::ConfigFile> m_config;
-    Vector<DeprecatedString> m_skip_directories;
-    Vector<DeprecatedString> m_skip_files;
-    Vector<DeprecatedString> m_failed_test_names;
+    Vector<ByteString> m_skip_directories;
+    Vector<ByteString> m_skip_files;
+    Vector<ByteString> m_failed_test_names;
     Regex<PosixExtended> m_skip_regex;
     bool m_run_skipped_tests { false };
     bool m_print_all_output { false };
     bool m_unlink_coredumps { false };
 };
 
-Vector<DeprecatedString> TestRunner::get_test_paths() const
+Vector<ByteString> TestRunner::get_test_paths() const
 {
-    Vector<DeprecatedString> paths;
-    Test::iterate_directory_recursively(m_test_root, [&](DeprecatedString const& file_path) {
+    Vector<ByteString> paths;
+    Test::iterate_directory_recursively(m_test_root, [&](ByteString const& file_path) {
         if (access(file_path.characters(), R_OK | X_OK) != 0)
             return;
         auto result = m_exclude_regex.match(file_path, PosixFlags::Global);
@@ -93,11 +93,11 @@ bool TestRunner::should_skip_test(LexicalPath const& test_path)
     if (m_run_skipped_tests)
         return false;
 
-    for (DeprecatedString const& dir : m_skip_directories) {
+    for (ByteString const& dir : m_skip_directories) {
         if (test_path.dirname().contains(dir))
             return true;
     }
-    for (DeprecatedString const& file : m_skip_files) {
+    for (ByteString const& file : m_skip_files) {
         if (test_path.basename().contains(file))
             return true;
     }
@@ -108,7 +108,7 @@ bool TestRunner::should_skip_test(LexicalPath const& test_path)
     return false;
 }
 
-void TestRunner::do_run_single_test(DeprecatedString const& test_path, size_t current_test_index, size_t num_tests)
+void TestRunner::do_run_single_test(ByteString const& test_path, size_t current_test_index, size_t num_tests)
 {
     g_currently_running_test = test_path;
     auto test_relative_path = LexicalPath::relative_path(test_path, m_test_root);
@@ -146,8 +146,8 @@ void TestRunner::do_run_single_test(DeprecatedString const& test_path, size_t cu
         out("{}", test_result.result == Test::Result::Fail ? " FAIL  " : "CRASHED");
         print_modifiers({ Test::CLEAR });
         if (test_result.result == Test::Result::Crashed) {
-            auto pid_search_string = DeprecatedString::formatted("_{}_", test_result.child_pid);
-            Optional<DeprecatedString> coredump_path;
+            auto pid_search_string = ByteString::formatted("_{}_", test_result.child_pid);
+            Optional<ByteString> coredump_path;
             Core::DirIterator iterator("/tmp/coredump"sv);
             if (!iterator.has_error()) {
                 while (iterator.has_next()) {
@@ -166,7 +166,7 @@ void TestRunner::do_run_single_test(DeprecatedString const& test_path, size_t cu
                         auto tid = thread_info.tid; // Note: Yoinking this out of the struct because we can't pass a reference to it (as it's a misaligned field in a packed struct)
                         dbgln("Thread {}", tid);
                         for (auto const& entry : thread_backtrace.entries())
-                            dbgln("- {}", entry.to_deprecated_string(true));
+                            dbgln("- {}", entry.to_byte_string(true));
                         return IterationDecision::Continue;
                     });
                     break;
@@ -235,7 +235,7 @@ void TestRunner::do_run_single_test(DeprecatedString const& test_path, size_t cu
     close(test_result.stdout_err_fd);
 }
 
-FileResult TestRunner::run_test_file(DeprecatedString const& test_path)
+FileResult TestRunner::run_test_file(ByteString const& test_path)
 {
     double start_time = get_time_in_ms();
 
@@ -251,8 +251,8 @@ FileResult TestRunner::run_test_file(DeprecatedString const& test_path)
     int child_out_err_file = mkstemp(child_out_err_path);
     VERIFY(child_out_err_file >= 0);
 
-    DeprecatedString dirname = path_for_test.dirname();
-    DeprecatedString basename = path_for_test.basename();
+    ByteString dirname = path_for_test.dirname();
+    ByteString basename = path_for_test.basename();
 
     (void)posix_spawn_file_actions_adddup2(&file_actions, child_out_err_file, STDOUT_FILENO);
     (void)posix_spawn_file_actions_adddup2(&file_actions, child_out_err_file, STDERR_FILENO);
@@ -327,9 +327,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     bool run_skipped_tests = false;
     bool unlink_coredumps = false;
     StringView specified_test_root;
-    DeprecatedString test_glob;
-    DeprecatedString exclude_pattern;
-    DeprecatedString config_file;
+    ByteString test_glob;
+    ByteString exclude_pattern;
+    ByteString config_file;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(Core::ArgsParser::Option {
@@ -358,7 +358,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.add_positional_argument(specified_test_root, "Tests root directory", "path", Core::ArgsParser::Required::No);
     args_parser.parse(arguments);
 
-    test_glob = DeprecatedString::formatted("*{}*", test_glob);
+    test_glob = ByteString::formatted("*{}*", test_glob);
 
     if (getenv("DISABLE_DBG_OUTPUT")) {
         AK::set_debug_enabled(false);
@@ -370,10 +370,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     if (!run_benchmarks)
         TRY(Core::System::setenv("TESTS_ONLY"sv, "1"sv, true));
 
-    DeprecatedString test_root;
+    ByteString test_root;
 
     if (!specified_test_root.is_empty()) {
-        test_root = DeprecatedString { specified_test_root };
+        test_root = ByteString { specified_test_root };
     } else {
         test_root = "/usr/Tests";
     }
@@ -382,7 +382,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return 1;
     }
 
-    test_root = TRY(FileSystem::real_path(test_root)).to_deprecated_string();
+    test_root = TRY(FileSystem::real_path(test_root)).to_byte_string();
 
     auto void_or_error = Core::System::chdir(test_root);
     if (void_or_error.is_error()) {
diff --git a/Userland/Utilities/sed.cpp b/Userland/Utilities/sed.cpp
index 92b153d0f15..4d5c890751e 100644
--- a/Userland/Utilities/sed.cpp
+++ b/Userland/Utilities/sed.cpp
@@ -711,7 +711,7 @@ private:
     OwnPtr<Core::File> m_output;
     OwnPtr<FileSystem::TempFile> m_output_temp_file;
     size_t m_line_number { 0 };
-    DeprecatedString m_current_line;
+    ByteString m_current_line;
     constexpr static size_t MAX_SUPPORTED_LINE_SIZE = 4096;
     Array<u8, MAX_SUPPORTED_LINE_SIZE> m_buffer;
 };
@@ -759,7 +759,7 @@ static void print_unambiguous(StringView pattern_space)
         else if (AK::is_ascii_printable(c))
             folded_append(c, 1);
         else
-            folded_append(DeprecatedString::formatted("\\{:3o}", (unsigned char)c), 4);
+            folded_append(ByteString::formatted("\\{:3o}", (unsigned char)c), 4);
     }
     outln("{}$", unambiguous_output.string_view());
 }
diff --git a/Userland/Utilities/shot.cpp b/Userland/Utilities/shot.cpp
index d06f6620a4a..421b05ce148 100644
--- a/Userland/Utilities/shot.cpp
+++ b/Userland/Utilities/shot.cpp
@@ -92,7 +92,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     Core::ArgsParser args_parser;
 
-    DeprecatedString output_path;
+    ByteString output_path;
     bool output_to_clipboard = false;
     unsigned delay = 0;
     bool select_region = false;
@@ -109,7 +109,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.parse(arguments);
 
     if (output_path.is_empty()) {
-        output_path = Core::DateTime::now().to_deprecated_string("screenshot-%Y-%m-%d-%H-%M-%S.png"sv);
+        output_path = Core::DateTime::now().to_byte_string("screenshot-%Y-%m-%d-%H-%M-%S.png"sv);
     }
 
     auto app = TRY(GUI::Application::create(arguments));
@@ -158,7 +158,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto encoded_bitmap = encoded_bitmap_or_error.release_value();
 
     if (edit_image)
-        output_path = Core::DateTime::now().to_deprecated_string("/tmp/screenshot-%Y-%m-%d-%H-%M-%S.png"sv);
+        output_path = Core::DateTime::now().to_byte_string("/tmp/screenshot-%Y-%m-%d-%H-%M-%S.png"sv);
 
     auto file_or_error = Core::File::open(output_path, Core::File::OpenMode::Write);
     if (file_or_error.is_error()) {
@@ -179,7 +179,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             char hostname[HOST_NAME_MAX];
             VERIFY(gethostname(hostname, sizeof(hostname)) == 0);
 
-            auto url = URL::create_with_file_scheme(full_path_or_error.value().to_deprecated_string(), {}, hostname);
+            auto url = URL::create_with_file_scheme(full_path_or_error.value().to_byte_string(), {}, hostname);
             out("\033]8;;{}\033\\", url.serialize());
             printed_hyperlink = true;
         }
diff --git a/Userland/Utilities/shutdown.cpp b/Userland/Utilities/shutdown.cpp
index c4cbfdfbcf0..811936b5574 100644
--- a/Userland/Utilities/shutdown.cpp
+++ b/Userland/Utilities/shutdown.cpp
@@ -6,7 +6,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/File.h>
 #include <LibMain/Main.h>
 #include <fcntl.h>
@@ -17,7 +17,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
 {
     auto file = TRY(Core::File::open("/sys/kernel/power_state"sv, Core::File::OpenMode::Write));
 
-    const DeprecatedString file_contents = "2";
+    const ByteString file_contents = "2";
     TRY(file->write_until_depleted(file_contents.bytes()));
     file->close();
 
diff --git a/Userland/Utilities/sort.cpp b/Userland/Utilities/sort.cpp
index 1d97118302d..42f230929c6 100644
--- a/Userland/Utilities/sort.cpp
+++ b/Userland/Utilities/sort.cpp
@@ -5,8 +5,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/HashMap.h>
 #include <AK/QuickSort.h>
 #include <AK/Vector.h>
@@ -18,7 +18,7 @@
 struct Line {
     StringView key;
     long int numeric_key;
-    DeprecatedString line;
+    ByteString line;
     bool numeric;
 
     bool operator<(Line const& other) const
@@ -58,7 +58,7 @@ struct Options {
     bool reverse { false };
     bool zero_terminated { false };
     StringView separator {};
-    Vector<DeprecatedString> files;
+    Vector<ByteString> files;
 };
 
 static ErrorOr<void> load_file(Options const& options, StringView filename, StringView line_delimiter, Vector<Line>& lines, HashTable<Line>& seen)
@@ -69,7 +69,7 @@ static ErrorOr<void> load_file(Options const& options, StringView filename, Stri
     // FIXME: Unlimited line length
     auto buffer = TRY(ByteBuffer::create_uninitialized(4096));
     while (TRY(file->can_read_line())) {
-        DeprecatedString line { TRY(file->read_until(buffer, line_delimiter)) };
+        ByteString line { TRY(file->read_until(buffer, line_delimiter)) };
         StringView key = line;
         if (options.key_field != 0) {
             auto split = (!options.separator.is_empty())
diff --git a/Userland/Utilities/sql.cpp b/Userland/Utilities/sql.cpp
index cdb6eff2326..d98269df1c2 100644
--- a/Userland/Utilities/sql.cpp
+++ b/Userland/Utilities/sql.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Format.h>
 #include <AK/String.h>
 #include <AK/StringBuilder.h>
@@ -21,7 +21,7 @@
 
 class SQLRepl {
 public:
-    explicit SQLRepl(Core::EventLoop& loop, DeprecatedString const& database_name, NonnullRefPtr<SQL::SQLClient> sql_client)
+    explicit SQLRepl(Core::EventLoop& loop, ByteString const& database_name, NonnullRefPtr<SQL::SQLClient> sql_client)
         : m_sql_client(move(sql_client))
         , m_loop(loop)
     {
@@ -85,7 +85,7 @@ public:
         m_sql_client->on_next_result = [](auto result) {
             StringBuilder builder;
             builder.join(", "sv, result.values);
-            outln("{}", builder.to_deprecated_string());
+            outln("{}", builder.to_byte_string());
         };
 
         m_sql_client->on_results_exhausted = [this](auto result) {
@@ -107,7 +107,7 @@ public:
         m_editor->save_history(m_history_path);
     }
 
-    void connect(DeprecatedString const& database_name)
+    void connect(ByteString const& database_name)
     {
         if (!m_database_name.is_empty()) {
             m_sql_client->disconnect(m_connection_id);
@@ -124,13 +124,13 @@ public:
         }
     }
 
-    void source_file(DeprecatedString file_name)
+    void source_file(ByteString file_name)
     {
         m_input_file_chain.append(move(file_name));
         m_quit_when_files_read = false;
     }
 
-    void read_file(DeprecatedString file_name)
+    void read_file(ByteString file_name)
     {
         m_input_file_chain.append(move(file_name));
         m_quit_when_files_read = true;
@@ -143,20 +143,20 @@ public:
     }
 
 private:
-    DeprecatedString m_history_path { DeprecatedString::formatted("{}/.sql-history", Core::StandardPaths::home_directory()) };
+    ByteString m_history_path { ByteString::formatted("{}/.sql-history", Core::StandardPaths::home_directory()) };
     RefPtr<Line::Editor> m_editor { nullptr };
     int m_repl_line_level { 0 };
     bool m_keep_running { true };
-    DeprecatedString m_database_name {};
+    ByteString m_database_name {};
     NonnullRefPtr<SQL::SQLClient> m_sql_client;
     SQL::ConnectionID m_connection_id { 0 };
     Core::EventLoop& m_loop;
     OwnPtr<Core::InputBufferedFile> m_input_file { nullptr };
     bool m_quit_when_files_read { false };
-    Vector<DeprecatedString> m_input_file_chain {};
+    Vector<ByteString> m_input_file_chain {};
     Array<u8, 4096> m_buffer {};
 
-    Optional<DeprecatedString> get_line()
+    Optional<ByteString> get_line()
     {
         if (!m_input_file && !m_input_file_chain.is_empty()) {
             auto file_name = m_input_file_chain.take_first();
@@ -196,7 +196,7 @@ private:
         return line_result.value();
     }
 
-    DeprecatedString read_next_piece()
+    ByteString read_next_piece()
     {
         StringBuilder piece;
 
@@ -250,12 +250,12 @@ private:
                 m_repl_line_level = last_token_ended_statement ? 0 : (m_repl_line_level > 0 ? m_repl_line_level : 1);
         } while ((m_repl_line_level > 0) || piece.is_empty());
 
-        return piece.to_deprecated_string();
+        return piece.to_byte_string();
     }
 
     void read_sql()
     {
-        DeprecatedString piece = read_next_piece();
+        ByteString piece = read_next_piece();
 
         // m_keep_running can be set to false when the file we are reading
         // from is exhausted...
@@ -288,7 +288,7 @@ private:
         }
     }
 
-    static DeprecatedString prompt_for_level(int level)
+    static ByteString prompt_for_level(int level)
     {
         static StringBuilder prompt_builder;
         prompt_builder.clear();
@@ -297,7 +297,7 @@ private:
         for (auto i = 0; i < level; ++i)
             prompt_builder.append("    "sv);
 
-        return prompt_builder.to_deprecated_string();
+        return prompt_builder.to_byte_string();
     }
 
     bool handle_command(StringView command)
@@ -334,11 +334,11 @@ private:
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
-    DeprecatedString database_name(getlogin());
-    DeprecatedString file_to_source;
-    DeprecatedString file_to_read;
+    ByteString database_name(getlogin());
+    ByteString file_to_source;
+    ByteString file_to_read;
     bool suppress_sqlrc = false;
-    auto sqlrc_path = DeprecatedString::formatted("{}/.sqlrc", Core::StandardPaths::home_directory());
+    auto sqlrc_path = ByteString::formatted("{}/.sqlrc", Core::StandardPaths::home_directory());
 #if !defined(AK_OS_SERENITY)
     StringView sql_server_path;
 #endif
diff --git a/Userland/Utilities/stat.cpp b/Userland/Utilities/stat.cpp
index 1d7c3c5c42d..2ae24403f2f 100644
--- a/Userland/Utilities/stat.cpp
+++ b/Userland/Utilities/stat.cpp
@@ -73,7 +73,7 @@ static ErrorOr<int> stat(StringView file, bool should_follow_links)
     outln(")");
 
     auto print_time = [](timespec t) {
-        outln("{}.{:09}", Core::DateTime::from_timestamp(t.tv_sec).to_deprecated_string(), t.tv_nsec);
+        outln("{}.{:09}", Core::DateTime::from_timestamp(t.tv_sec).to_byte_string(), t.tv_nsec);
     };
 
     out("Accessed: ");
diff --git a/Userland/Utilities/strace.cpp b/Userland/Utilities/strace.cpp
index 71c5c8edd1b..fbb9b86a412 100644
--- a/Userland/Utilities/strace.cpp
+++ b/Userland/Utilities/strace.cpp
@@ -34,13 +34,13 @@
 #define HANDLE(VALUE) \
     case VALUE:       \
         return #VALUE##sv;
-#define VALUES_TO_NAMES(FUNC_NAME)               \
-    static DeprecatedString FUNC_NAME(int value) \
-    {                                            \
+#define VALUES_TO_NAMES(FUNC_NAME)         \
+    static ByteString FUNC_NAME(int value) \
+    {                                      \
         switch (value) {
-#define END_VALUES_TO_NAMES()                        \
-    }                                                \
-    return DeprecatedString::formatted("{}", value); \
+#define END_VALUES_TO_NAMES()                  \
+    }                                          \
+    return ByteString::formatted("{}", value); \
     }
 
 VALUES_TO_NAMES(errno_name)
@@ -613,7 +613,7 @@ struct Formatter<struct sockaddr> : StandardFormatter {
             builder.appendff(
                 ", sin_port={}, sin_addr={}",
                 address_in->sin_port,
-                IPv4Address(address_in->sin_addr.s_addr).to_deprecated_string());
+                IPv4Address(address_in->sin_addr.s_addr).to_byte_string());
         } else if (address.sa_family == AF_UNIX) {
             auto* address_un = (const struct sockaddr_un*)&address;
             builder.appendff(
diff --git a/Userland/Utilities/stty.cpp b/Userland/Utilities/stty.cpp
index 7e277f82e36..3e634c1abe1 100644
--- a/Userland/Utilities/stty.cpp
+++ b/Userland/Utilities/stty.cpp
@@ -7,8 +7,8 @@
 
 #define __USE_MISC
 #define TTYDEFCHARS
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Optional.h>
 #include <AK/Result.h>
 #include <AK/ScopeGuard.h>
@@ -212,7 +212,7 @@ void print_human_readable(termios const& modes, winsize const& ws, bool verbose_
         } else {
             sb.append(ch);
         }
-        return sb.to_deprecated_string();
+        return sb.to_byte_string();
     };
 
     auto print_control_characters = [&] {
@@ -536,7 +536,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::unveil("/dev", "r"));
     TRY(Core::System::unveil(nullptr, nullptr));
 
-    DeprecatedString device_file;
+    ByteString device_file;
     bool stty_readable = false;
     bool all_settings = false;
 
diff --git a/Userland/Utilities/syscall.cpp b/Userland/Utilities/syscall.cpp
index 0e9e9807805..f5f754f831f 100644
--- a/Userland/Utilities/syscall.cpp
+++ b/Userland/Utilities/syscall.cpp
@@ -24,7 +24,7 @@
 FlatPtr arg[SC_NARG];
 char outbuf[BUFSIZ];
 
-using Arguments = Vector<DeprecatedString>;
+using Arguments = Vector<ByteString>;
 using ArgIter = Arguments::Iterator;
 
 static FlatPtr parse_from(ArgIter&);
@@ -128,7 +128,7 @@ static FlatPtr as_buf(Vector<FlatPtr> params_vec)
             builder.appendff(" {:p}", params_vec[i]);
         }
         builder.appendff(" ] at {:p}", (FlatPtr)buf);
-        dbgln("{}", builder.to_deprecated_string());
+        dbgln("{}", builder.to_byte_string());
     }
 
     // Leak the buffer here. We need to keep it until the special syscall happens,
diff --git a/Userland/Utilities/sysctl.cpp b/Userland/Utilities/sysctl.cpp
index c7cece91178..f998749c56d 100644
--- a/Userland/Utilities/sysctl.cpp
+++ b/Userland/Utilities/sysctl.cpp
@@ -12,9 +12,9 @@
 
 static bool s_set_variable = false;
 
-static Optional<DeprecatedString> get_variable(StringView name)
+static Optional<ByteString> get_variable(StringView name)
 {
-    auto path = DeprecatedString::formatted("/sys/kernel/conf/{}", name);
+    auto path = ByteString::formatted("/sys/kernel/conf/{}", name);
     auto file = Core::File::open(path, Core::File::OpenMode::Read);
     if (file.is_error()) {
         warnln("Failed to open {}: {}", path, file.error());
@@ -25,7 +25,7 @@ static Optional<DeprecatedString> get_variable(StringView name)
         warnln("Failed to read {}: {}", path, buffer.error());
         return {};
     }
-    return DeprecatedString { (char const*)buffer.value().data(), buffer.value().size(), Chomp };
+    return ByteString { (char const*)buffer.value().data(), buffer.value().size(), Chomp };
 }
 
 static bool read_variable(StringView name)
@@ -42,7 +42,7 @@ static bool write_variable(StringView name, StringView value)
     auto old_value = get_variable(name);
     if (!old_value.has_value())
         return false;
-    auto path = DeprecatedString::formatted("/sys/kernel/conf/{}", name);
+    auto path = ByteString::formatted("/sys/kernel/conf/{}", name);
     auto file = Core::File::open(path, Core::File::OpenMode::Write);
     if (file.is_error()) {
         warnln("Failed to open {}: {}", path, file.error());
diff --git a/Userland/Utilities/tac.cpp b/Userland/Utilities/tac.cpp
index 36fc3c0de09..0e787e9db35 100644
--- a/Userland/Utilities/tac.cpp
+++ b/Userland/Utilities/tac.cpp
@@ -32,7 +32,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             if (path == "-"sv) {
                 stream = stdin;
             } else {
-                stream = fopen(DeprecatedString(path).characters(), "r");
+                stream = fopen(ByteString(path).characters(), "r");
                 if (!stream) {
                     warnln("Failed to open {}: {}", path, strerror(errno));
                     continue;
@@ -56,7 +56,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::pledge("stdio"));
 
     for (auto* stream : streams) {
-        Vector<DeprecatedString> lines;
+        Vector<ByteString> lines;
         for (;;) {
             size_t n = 0;
             errno = 0;
diff --git a/Userland/Utilities/tail.cpp b/Userland/Utilities/tail.cpp
index 6ed396c5350..228d6a4d515 100644
--- a/Userland/Utilities/tail.cpp
+++ b/Userland/Utilities/tail.cpp
@@ -86,7 +86,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 line.append(ch);
                 if (ch == '\n' || i == bytes.size() - 1) {
                     if (wanted_line_count > line_count || line_index >= line_count - wanted_line_count)
-                        out("{}", line.to_deprecated_string());
+                        out("{}", line.to_byte_string());
                     line_index++;
                     line.clear();
                 }
diff --git a/Userland/Utilities/tar.cpp b/Userland/Utilities/tar.cpp
index 15f9962a026..a0ed7ccebb2 100644
--- a/Userland/Utilities/tar.cpp
+++ b/Userland/Utilities/tar.cpp
@@ -5,7 +5,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/LexicalPath.h>
 #include <AK/Span.h>
@@ -40,7 +40,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     StringView archive_file;
     bool dereference;
     StringView directory;
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(create, "Create archive", "create", 'c');
@@ -88,16 +88,16 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         auto tar_stream = TRY(Archive::TarInputStream::construct(move(input_stream)));
 
-        HashMap<DeprecatedString, DeprecatedString> global_overrides;
-        HashMap<DeprecatedString, DeprecatedString> local_overrides;
+        HashMap<ByteString, ByteString> global_overrides;
+        HashMap<ByteString, ByteString> local_overrides;
 
-        auto get_override = [&](StringView key) -> Optional<DeprecatedString> {
-            Optional<DeprecatedString> maybe_local = local_overrides.get(key);
+        auto get_override = [&](StringView key) -> Optional<ByteString> {
+            Optional<ByteString> maybe_local = local_overrides.get(key);
 
             if (maybe_local.has_value())
                 return maybe_local;
 
-            Optional<DeprecatedString> maybe_global = global_overrides.get(key);
+            Optional<ByteString> maybe_global = global_overrides.get(key);
 
             if (maybe_global.has_value())
                 return maybe_global;
@@ -149,7 +149,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                     long_name.append(reinterpret_cast<char*>(slice.data()), slice.size());
                 }
 
-                local_overrides.set("path", long_name.to_deprecated_string());
+                local_overrides.set("path", long_name.to_byte_string());
                 TRY(tar_stream->advance());
                 continue;
             }
@@ -161,13 +161,13 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             LexicalPath path = LexicalPath(header.filename());
             if (!header.prefix().is_empty())
                 path = path.prepend(header.prefix());
-            DeprecatedString filename = get_override("path"sv).value_or(path.string());
+            ByteString filename = get_override("path"sv).value_or(path.string());
 
             if (list || verbose)
                 outln("{}", filename);
 
             if (extract) {
-                DeprecatedString absolute_path = TRY(FileSystem::absolute_path(filename)).to_deprecated_string();
+                ByteString absolute_path = TRY(FileSystem::absolute_path(filename)).to_byte_string();
                 auto parent_path = LexicalPath(absolute_path).parent();
                 auto header_mode = TRY(header.mode());
 
@@ -242,7 +242,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         Archive::TarOutputStream tar_stream(move(output_stream));
 
-        auto add_file = [&](DeprecatedString path) -> ErrorOr<void> {
+        auto add_file = [&](ByteString path) -> ErrorOr<void> {
             auto file_or_error = Core::File::open(path, Core::File::OpenMode::Read);
             if (file_or_error.is_error()) {
                 warnln("Failed to open {}: {}", path, file_or_error.error());
@@ -251,7 +251,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             auto file = file_or_error.release_value();
 
             auto statbuf = TRY(Core::System::lstat(path));
-            auto canonicalized_path = TRY(String::from_deprecated_string(LexicalPath::canonicalized_path(path)));
+            auto canonicalized_path = TRY(String::from_byte_string(LexicalPath::canonicalized_path(path)));
             // FIXME: We should stream instead of reading the entire file in one go, but TarOutputStream does not have any interface to do so.
             auto file_content = TRY(file->read_until_eof());
             TRY(tar_stream.add_file(canonicalized_path, statbuf.st_mode, file_content));
@@ -261,10 +261,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             return {};
         };
 
-        auto add_link = [&](DeprecatedString path) -> ErrorOr<void> {
+        auto add_link = [&](ByteString path) -> ErrorOr<void> {
             auto statbuf = TRY(Core::System::lstat(path));
 
-            auto canonicalized_path = TRY(String::from_deprecated_string(LexicalPath::canonicalized_path(path)));
+            auto canonicalized_path = TRY(String::from_byte_string(LexicalPath::canonicalized_path(path)));
             TRY(tar_stream.add_link(canonicalized_path, statbuf.st_mode, TRY(Core::System::readlink(path))));
             if (verbose)
                 outln("{}", canonicalized_path);
@@ -272,10 +272,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             return {};
         };
 
-        auto add_directory = [&](DeprecatedString path, auto handle_directory) -> ErrorOr<void> {
+        auto add_directory = [&](ByteString path, auto handle_directory) -> ErrorOr<void> {
             auto statbuf = TRY(Core::System::lstat(path));
 
-            auto canonicalized_path = TRY(String::from_deprecated_string(LexicalPath::canonicalized_path(path)));
+            auto canonicalized_path = TRY(String::from_byte_string(LexicalPath::canonicalized_path(path)));
             TRY(tar_stream.add_directory(canonicalized_path, statbuf.st_mode));
             if (verbose)
                 outln("{}", canonicalized_path);
diff --git a/Userland/Utilities/telws.cpp b/Userland/Utilities/telws.cpp
index 406d295468a..22f0fd55b4b 100644
--- a/Userland/Utilities/telws.cpp
+++ b/Userland/Utilities/telws.cpp
@@ -21,8 +21,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     Core::ArgsParser args_parser;
 
-    DeprecatedString origin;
-    DeprecatedString url_string;
+    ByteString origin;
+    ByteString url_string;
 
     args_parser.add_positional_argument(url_string, "URL to connect to", "url", Core::ArgsParser::Required::Yes);
     args_parser.add_option(origin, "URL to use as origin", "origin", 'o', "origin");
@@ -63,7 +63,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             outln("[Received binary data : {} bytes]", message.data.size());
             return;
         }
-        outln("[Received utf8 text] {}", DeprecatedString(ReadonlyBytes(message.data)));
+        outln("[Received utf8 text] {}", ByteString(ReadonlyBytes(message.data)));
     };
     socket->on_close = [&](auto code, auto message, bool was_clean) {
         outln("[Server {} closed connection : '{}' (code {})]",
diff --git a/Userland/Utilities/test-imap.cpp b/Userland/Utilities/test-imap.cpp
index 4d9f57ac9c8..c026986044b 100644
--- a/Userland/Utilities/test-imap.cpp
+++ b/Userland/Utilities/test-imap.cpp
@@ -18,11 +18,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return 1;
     }
 
-    DeprecatedString host;
+    ByteString host;
     int port;
     bool tls { false };
 
-    DeprecatedString username;
+    ByteString username;
     Core::SecretString password;
     bool interactive_password;
 
@@ -125,7 +125,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 .first()
                 .get<IMAP::FetchResponseData>()
                 .body_data()
-                .find_if([](Tuple<IMAP::FetchCommand::DataItem, DeprecatedString>& data) {
+                .find_if([](Tuple<IMAP::FetchCommand::DataItem, ByteString>& data) {
                     const auto data_item = data.get<0>();
                     return data_item.section.has_value() && data_item.section->type == IMAP::FetchCommand::DataItem::SectionType::HeaderFields;
                 })
diff --git a/Userland/Utilities/test.cpp b/Userland/Utilities/test.cpp
index 79b6cc34f8d..96bd6099539 100644
--- a/Userland/Utilities/test.cpp
+++ b/Userland/Utilities/test.cpp
@@ -143,7 +143,7 @@ private:
         }
     }
 
-    DeprecatedString m_path;
+    ByteString m_path;
     Kind m_kind { Regular };
 };
 
@@ -178,7 +178,7 @@ private:
         }
     }
 
-    DeprecatedString m_path;
+    ByteString m_path;
     Permission m_kind { Read };
 };
 
@@ -221,7 +221,7 @@ private:
         }
     }
 
-    DeprecatedString m_path;
+    ByteString m_path;
     Flag m_kind { SGID };
 };
 
@@ -261,7 +261,7 @@ private:
         }
     }
 
-    DeprecatedString m_path;
+    ByteString m_path;
     Owner m_kind { EffectiveGID };
 };
 
@@ -303,7 +303,7 @@ public:
         NotEqual,
     };
 
-    NumericCompare(DeprecatedString lhs, DeprecatedString rhs, Mode mode)
+    NumericCompare(ByteString lhs, ByteString rhs, Mode mode)
         : m_mode(mode)
     {
         auto lhs_option = lhs.trim_whitespace().to_int();
@@ -353,7 +353,7 @@ public:
         ModificationTimestampLess,
     };
 
-    FileCompare(DeprecatedString lhs, DeprecatedString rhs, Mode mode)
+    FileCompare(ByteString lhs, ByteString rhs, Mode mode)
         : m_lhs(move(lhs))
         , m_rhs(move(rhs))
         , m_mode(mode)
@@ -393,8 +393,8 @@ private:
         }
     }
 
-    DeprecatedString m_lhs;
-    DeprecatedString m_rhs;
+    ByteString m_lhs;
+    ByteString m_rhs;
     Mode m_mode { Same };
 };
 
diff --git a/Userland/Utilities/top.cpp b/Userland/Utilities/top.cpp
index 19b54320f1c..ca36a622497 100644
--- a/Userland/Utilities/top.cpp
+++ b/Userland/Utilities/top.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/HashMap.h>
 #include <AK/JsonArray.h>
 #include <AK/JsonObject.h>
@@ -47,8 +47,8 @@ struct ThreadData {
     uid_t uid;
     gid_t gid;
     pid_t ppid;
-    DeprecatedString name;
-    DeprecatedString tty;
+    ByteString name;
+    ByteString tty;
     size_t amount_virtual;
     size_t amount_resident;
     size_t amount_shared;
@@ -63,8 +63,8 @@ struct ThreadData {
     unsigned cpu_percent_decimal { 0 };
 
     u32 priority;
-    DeprecatedString username;
-    DeprecatedString state;
+    ByteString username;
+    ByteString state;
 };
 
 struct PidAndTid {
diff --git a/Userland/Utilities/touch.cpp b/Userland/Utilities/touch.cpp
index ce12d4ccdf4..2f7fcdf95c7 100644
--- a/Userland/Utilities/touch.cpp
+++ b/Userland/Utilities/touch.cpp
@@ -22,7 +22,7 @@
 #include <sys/stat.h>
 #include <time.h>
 
-static DeprecatedString program_name;
+static ByteString program_name;
 
 template<typename... Parameters>
 [[noreturn]] static void err(CheckedFormatString<Parameters...>&& fmtstr, Parameters const&... parameters)
@@ -192,7 +192,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     program_name = arguments.strings[0];
 
-    Vector<DeprecatedString> paths;
+    Vector<ByteString> paths;
 
     timespec times[2];
     auto& atime = times[0];
@@ -202,9 +202,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     bool update_mtime = false;
     bool no_create_file = false;
 
-    DeprecatedString input_datetime = "";
-    DeprecatedString input_time = "";
-    DeprecatedString reference_path = "";
+    ByteString input_datetime = "";
+    ByteString input_time = "";
+    ByteString reference_path = "";
 
     Core::ArgsParser args_parser;
     args_parser.set_general_help("Create a file or update file access time and/or modification time.");
diff --git a/Userland/Utilities/tr.cpp b/Userland/Utilities/tr.cpp
index 2c82d994d5d..974a49010b9 100644
--- a/Userland/Utilities/tr.cpp
+++ b/Userland/Utilities/tr.cpp
@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/GenericLexer.h>
 #include <AK/Optional.h>
 #include <LibCore/ArgsParser.h>
@@ -28,7 +28,7 @@ static ErrorOr<void> generate_character_class(Function<int(int)> oracle, StringB
     return {};
 }
 
-static ErrorOr<DeprecatedString> build_set(StringView specification)
+static ErrorOr<ByteString> build_set(StringView specification)
 {
     StringBuilder out;
     GenericLexer lexer(specification);
@@ -89,7 +89,7 @@ static ErrorOr<DeprecatedString> build_set(StringView specification)
             TRY(out.try_append(lexer.consume(1)));
     }
 
-    return out.to_deprecated_string();
+    return out.to_byte_string();
 }
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
@@ -135,7 +135,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             if (!from_str.contains(static_cast<char>(ch)))
                 TRY(complement_set.try_append(static_cast<char>(ch)));
         }
-        from_str = complement_set.to_deprecated_string();
+        from_str = complement_set.to_byte_string();
     }
 
     auto to_str = TRY(build_set(to_chars));
diff --git a/Userland/Utilities/traceroute.cpp b/Userland/Utilities/traceroute.cpp
index 1ad19bdbc18..3a075237e34 100644
--- a/Userland/Utilities/traceroute.cpp
+++ b/Userland/Utilities/traceroute.cpp
@@ -5,7 +5,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/ElapsedTimer.h>
 #include <LibCore/System.h>
@@ -25,7 +25,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio id inet unix"));
 
-    DeprecatedString host_name;
+    ByteString host_name;
     int max_hops = 30;
     int max_retries = 3;
     int echo_timeout = 5;
@@ -79,7 +79,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     // -1: error or no response
     auto try_reach_host = [&](int ttl) -> ErrorOr<int> {
         Core::ElapsedTimer m_timer { true };
-        auto ttl_number = DeprecatedString::number(ttl);
+        auto ttl_number = ByteString::number(ttl);
         for (auto i = 0; i < max_retries; i++) {
             icmp_request request {};
             request.header = { ICMP_ECHO, 0, 0, { { 0, 0 } } };
@@ -107,7 +107,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             auto response_time = m_timer.elapsed();
             auto* peer = gethostbyaddr(&peer_address.sin_addr, sizeof(peer_address.sin_addr), AF_INET);
 
-            DeprecatedString peer_name;
+            ByteString peer_name;
             if (peer) {
                 peer_name = peer->h_name;
             } else {
diff --git a/Userland/Utilities/tree.cpp b/Userland/Utilities/tree.cpp
index 5038dd3432f..006c79bedf4 100644
--- a/Userland/Utilities/tree.cpp
+++ b/Userland/Utilities/tree.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/LexicalPath.h>
 #include <AK/QuickSort.h>
 #include <AK/StringBuilder.h>
@@ -27,10 +27,10 @@ static int max_depth = INT_MAX;
 static int g_directories_seen = 0;
 static int g_files_seen = 0;
 
-static void print_directory_tree(DeprecatedString const& root_path, int depth, DeprecatedString const& indent_string)
+static void print_directory_tree(ByteString const& root_path, int depth, ByteString const& indent_string)
 {
     if (depth > 0) {
-        DeprecatedString root_indent_string;
+        ByteString root_indent_string;
         if (depth > 1) {
             root_indent_string = indent_string.substring(0, (depth - 1) * 4);
         } else {
@@ -39,7 +39,7 @@ static void print_directory_tree(DeprecatedString const& root_path, int depth, D
         out("{}|-- ", root_indent_string);
     }
 
-    DeprecatedString root_dir_name = LexicalPath::basename(root_path);
+    ByteString root_dir_name = LexicalPath::basename(root_path);
     out("\033[34;1m{}\033[0m\n", root_dir_name);
 
     if (depth >= max_depth) {
@@ -52,9 +52,9 @@ static void print_directory_tree(DeprecatedString const& root_path, int depth, D
         return;
     }
 
-    Vector<DeprecatedString> names;
+    Vector<ByteString> names;
     while (di.has_next()) {
-        DeprecatedString name = di.next_path();
+        ByteString name = di.next_path();
         if (di.has_error()) {
             warnln("{}: {}", root_path, di.error());
             continue;
@@ -65,7 +65,7 @@ static void print_directory_tree(DeprecatedString const& root_path, int depth, D
     quick_sort(names);
 
     for (size_t i = 0; i < names.size(); i++) {
-        DeprecatedString name = names[i];
+        ByteString name = names[i];
 
         StringBuilder builder;
         builder.append(root_path);
@@ -73,7 +73,7 @@ static void print_directory_tree(DeprecatedString const& root_path, int depth, D
             builder.append('/');
         }
         builder.append(name);
-        auto full_path = builder.to_deprecated_string();
+        auto full_path = builder.to_byte_string();
 
         struct stat st;
         int rc = lstat(full_path.characters(), &st);
@@ -86,11 +86,11 @@ static void print_directory_tree(DeprecatedString const& root_path, int depth, D
             g_directories_seen++;
 
             bool at_last_entry = i == names.size() - 1;
-            DeprecatedString new_indent_string;
+            ByteString new_indent_string;
             if (at_last_entry) {
-                new_indent_string = DeprecatedString::formatted("{}    ", indent_string);
+                new_indent_string = ByteString::formatted("{}    ", indent_string);
             } else {
-                new_indent_string = DeprecatedString::formatted("{}|   ", indent_string);
+                new_indent_string = ByteString::formatted("{}|   ", indent_string);
             }
 
             print_directory_tree(full_path.characters(), depth + 1, new_indent_string);
@@ -106,7 +106,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio rpath tty"));
 
-    Vector<DeprecatedString> directories;
+    Vector<ByteString> directories;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(flag_show_hidden_files, "Show hidden files", "all", 'a');
diff --git a/Userland/Utilities/uname.cpp b/Userland/Utilities/uname.cpp
index 9edae1cf172..953458595b3 100644
--- a/Userland/Utilities/uname.cpp
+++ b/Userland/Utilities/uname.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <AK/Vector.h>
 #include <LibCore/ArgsParser.h>
@@ -41,7 +41,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     utsname uts = TRY(Core::System::uname());
 
-    Vector<DeprecatedString> parts;
+    Vector<ByteString> parts;
     if (flag_system)
         parts.append(uts.sysname);
     if (flag_node)
@@ -54,6 +54,6 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         parts.append(uts.machine);
     StringBuilder builder;
     builder.join(' ', parts);
-    puts(builder.to_deprecated_string().characters());
+    puts(builder.to_byte_string().characters());
     return 0;
 }
diff --git a/Userland/Utilities/uniq.cpp b/Userland/Utilities/uniq.cpp
index e8f5abe82d4..a7799830945 100644
--- a/Userland/Utilities/uniq.cpp
+++ b/Userland/Utilities/uniq.cpp
@@ -18,9 +18,9 @@ static ErrorOr<void> write_line_content(StringView line, size_t count, bool dupl
         return {};
 
     if (print_count)
-        TRY(outfile.write_until_depleted(DeprecatedString::formatted("{} {}\n", count, line).bytes()));
+        TRY(outfile.write_until_depleted(ByteString::formatted("{} {}\n", count, line).bytes()));
     else
-        TRY(outfile.write_until_depleted(DeprecatedString::formatted("{}\n", line).bytes()));
+        TRY(outfile.write_until_depleted(ByteString::formatted("{}\n", line).bytes()));
     return {};
 }
 
diff --git a/Userland/Utilities/unveil.cpp b/Userland/Utilities/unveil.cpp
index 4683585a870..9eea4c16e86 100644
--- a/Userland/Utilities/unveil.cpp
+++ b/Userland/Utilities/unveil.cpp
@@ -12,7 +12,7 @@
 
 ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
-    Vector<DeprecatedString> unveil_paths;
+    Vector<ByteString> unveil_paths;
     Vector<StringView> command;
 
     Core::ArgsParser args_parser;
diff --git a/Userland/Utilities/unzip.cpp b/Userland/Utilities/unzip.cpp
index 440ba687bf6..2c643d70e7a 100644
--- a/Userland/Utilities/unzip.cpp
+++ b/Userland/Utilities/unzip.cpp
@@ -43,8 +43,8 @@ static bool unpack_zip_member(Archive::ZipMember zip_member, bool quiet)
             outln(" extracting: {}", zip_member.name);
         return true;
     }
-    MUST(Core::Directory::create(LexicalPath(zip_member.name.to_deprecated_string()).parent(), Core::Directory::CreateDirectories::Yes));
-    auto new_file_or_error = Core::File::open(zip_member.name.to_deprecated_string(), Core::File::OpenMode::Write);
+    MUST(Core::Directory::create(LexicalPath(zip_member.name.to_byte_string()).parent(), Core::Directory::CreateDirectories::Yes));
+    auto new_file_or_error = Core::File::open(zip_member.name.to_byte_string(), Core::File::OpenMode::Write);
     if (new_file_or_error.is_error()) {
         warnln("Can't write file {}: {}", zip_member.name, new_file_or_error.release_error());
         return false;
diff --git a/Userland/Utilities/update-cpp-test-results.cpp b/Userland/Utilities/update-cpp-test-results.cpp
index aae829db2ed..7fe83596b9e 100644
--- a/Userland/Utilities/update-cpp-test-results.cpp
+++ b/Userland/Utilities/update-cpp-test-results.cpp
@@ -20,7 +20,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
             continue;
         auto ast_full_path = cpp_full_path.replace(".cpp"sv, ".ast"sv, ReplaceMode::FirstOnly);
         outln("{}", cpp_full_path);
-        auto res = Core::command("/bin/sh", { "-c", DeprecatedString::formatted("cpp-parser {} > {}", cpp_full_path, ast_full_path) }, {});
+        auto res = Core::command("/bin/sh", { "-c", ByteString::formatted("cpp-parser {} > {}", cpp_full_path, ast_full_path) }, {});
         VERIFY(!res.is_error());
     }
 
@@ -31,7 +31,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
             continue;
         auto ast_full_path = cpp_full_path.replace(".cpp"sv, ".txt"sv, ReplaceMode::FirstOnly);
         outln("{}", cpp_full_path);
-        auto res = Core::command("/bin/sh", { "-c", DeprecatedString::formatted("cpp-preprocessor {} > {}", cpp_full_path, ast_full_path) }, {});
+        auto res = Core::command("/bin/sh", { "-c", ByteString::formatted("cpp-preprocessor {} > {}", cpp_full_path, ast_full_path) }, {});
         VERIFY(!res.is_error());
     }
 
diff --git a/Userland/Utilities/useradd.cpp b/Userland/Utilities/useradd.cpp
index f12be485816..8366fc00f4a 100644
--- a/Userland/Utilities/useradd.cpp
+++ b/Userland/Utilities/useradd.cpp
@@ -8,8 +8,8 @@
  */
 
 #include <AK/Base64.h>
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Random.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/System.h>
@@ -58,10 +58,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     uid_t uid = 0;
     gid_t gid = USERS_GID;
     bool create_home_dir = false;
-    DeprecatedString password = "";
-    DeprecatedString shell = DEFAULT_SHELL;
-    DeprecatedString gecos = "";
-    DeprecatedString username;
+    ByteString password = "";
+    ByteString shell = DEFAULT_SHELL;
+    ByteString gecos = "";
+    ByteString username;
 
     Core::ArgsParser args_parser;
     args_parser.add_option(home_path, "Home directory for the new user", "home-dir", 'd', "path");
@@ -92,7 +92,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     }
 
     // Let's run a quick sanity check on username
-    if (username.find_any_of("\\/!@#$%^&*()~+=`:\n"sv, DeprecatedString::SearchDirection::Forward).has_value()) {
+    if (username.find_any_of("\\/!@#$%^&*()~+=`:\n"sv, ByteString::SearchDirection::Forward).has_value()) {
         warnln("invalid character in username, {}", username);
         return 1;
     }
@@ -136,9 +136,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         return 1;
     }
 
-    DeprecatedString home;
+    ByteString home;
     if (home_path.is_empty())
-        home = DeprecatedString::formatted("/home/{}", username);
+        home = ByteString::formatted("/home/{}", username);
     else
         home = home_path;
 
@@ -163,7 +163,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         }
     }
 
-    auto get_salt = []() -> ErrorOr<DeprecatedString> {
+    auto get_salt = []() -> ErrorOr<ByteString> {
         char random_data[12];
         fill_with_random({ random_data, sizeof(random_data) });
 
@@ -171,7 +171,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         builder.append("$5$"sv);
         builder.append(TRY(encode_base64({ random_data, sizeof(random_data) })));
 
-        return builder.to_deprecated_string();
+        return builder.to_byte_string();
     };
 
     char* hash = crypt(password.characters(), TRY(get_salt()).characters());
diff --git a/Userland/Utilities/utmpupdate.cpp b/Userland/Utilities/utmpupdate.cpp
index 77d98b1f161..f03a72e1e38 100644
--- a/Userland/Utilities/utmpupdate.cpp
+++ b/Userland/Utilities/utmpupdate.cpp
@@ -72,7 +72,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     TRY(file->seek(0, SeekMode::SetPosition));
     TRY(file->truncate(0));
-    TRY(file->write_until_depleted(json.to_deprecated_string().bytes()));
+    TRY(file->write_until_depleted(json.to_byte_string().bytes()));
 
     return 0;
 }
diff --git a/Userland/Utilities/w.cpp b/Userland/Utilities/w.cpp
index 7410c731069..131291cf8fd 100644
--- a/Userland/Utilities/w.cpp
+++ b/Userland/Utilities/w.cpp
@@ -79,7 +79,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
         auto maybe_account = Core::Account::from_uid(uid, Core::Account::Read::PasswdOnly);
         String username;
         if (!maybe_account.is_error())
-            username = TRY(String::from_deprecated_string(maybe_account.release_value().username()));
+            username = TRY(String::from_byte_string(maybe_account.release_value().username()));
         else
             username = TRY(String::formatted("{}", uid));
 
@@ -103,7 +103,7 @@ ErrorOr<int> serenity_main(Main::Arguments args)
             tty_display_name = tty_pseudo_name;
             for (auto& process : process_statistics.processes) {
                 if (tty_pseudo_name == process.tty.view() && process.pid == process.pgid) {
-                    what = TRY(String::from_deprecated_string(process.name));
+                    what = TRY(String::from_byte_string(process.name));
                     break;
                 }
             }
diff --git a/Userland/Utilities/wallpaper.cpp b/Userland/Utilities/wallpaper.cpp
index 4b6fe00b2cc..9485d88f5bd 100644
--- a/Userland/Utilities/wallpaper.cpp
+++ b/Userland/Utilities/wallpaper.cpp
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/Random.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/ArgsParser.h>
@@ -52,7 +52,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
         if (wallpapers_directory_iterator.has_error())
             return Error::from_string_literal("Unable to iterate /res/wallpapers directory");
 
-        Vector<DeprecatedString> wallpaper_paths;
+        Vector<ByteString> wallpaper_paths;
 
         auto current_wallpaper_path = GUI::Desktop::the().wallpaper_path();
         while (wallpapers_directory_iterator.has_next()) {
diff --git a/Userland/Utilities/wasm.cpp b/Userland/Utilities/wasm.cpp
index 0f2f5373d36..96701350958 100644
--- a/Userland/Utilities/wasm.cpp
+++ b/Userland/Utilities/wasm.cpp
@@ -57,14 +57,14 @@ static bool pre_interpret_hook(Wasm::Configuration& config, Wasm::InstructionPoi
     if (always_print_stack)
         config.dump_stack();
     if (always_print_instruction) {
-        g_stdout->write_until_depleted(DeprecatedString::formatted("{:0>4} ", ip.value()).bytes()).release_value_but_fixme_should_propagate_errors();
+        g_stdout->write_until_depleted(ByteString::formatted("{:0>4} ", ip.value()).bytes()).release_value_but_fixme_should_propagate_errors();
         g_printer->print(instr);
     }
     if (g_continue)
         return true;
-    g_stdout->write_until_depleted(DeprecatedString::formatted("{:0>4} ", ip.value()).bytes()).release_value_but_fixme_should_propagate_errors();
+    g_stdout->write_until_depleted(ByteString::formatted("{:0>4} ", ip.value()).bytes()).release_value_but_fixme_should_propagate_errors();
     g_printer->print(instr);
-    DeprecatedString last_command = "";
+    ByteString last_command = "";
     for (;;) {
         auto result = g_line_editor->get_line("> ");
         if (result.is_error()) {
@@ -261,7 +261,7 @@ static Optional<Wasm::Module> parse(StringView filename)
     auto parse_result = Wasm::Module::parse(*result.value());
     if (parse_result.is_error()) {
         warnln("Something went wrong, either the file is invalid, or there's a bug with LibWasm!");
-        warnln("The parse error was {}", Wasm::parse_error_to_deprecated_string(parse_result.error()));
+        warnln("The parse error was {}", Wasm::parse_error_to_byte_string(parse_result.error()));
         return {};
     }
     return parse_result.release_value();
@@ -282,9 +282,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     bool export_all_imports = false;
     bool shell_mode = false;
     bool wasi = false;
-    DeprecatedString exported_function_to_execute;
+    ByteString exported_function_to_execute;
     Vector<u64> values_to_push;
-    Vector<DeprecatedString> modules_to_link_in;
+    Vector<ByteString> modules_to_link_in;
     Vector<StringView> args_if_wasi;
     Vector<StringView> wasi_preopened_mappings;
 
@@ -388,11 +388,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                     for (auto& string : wasi_preopened_mappings) {
                         auto split_index = string.find(':');
                         if (split_index.has_value()) {
-                            LexicalPath host_path { FileSystem::real_path(string.substring_view(0, *split_index)).release_value_but_fixme_should_propagate_errors().to_deprecated_string() };
+                            LexicalPath host_path { FileSystem::real_path(string.substring_view(0, *split_index)).release_value_but_fixme_should_propagate_errors().to_byte_string() };
                             LexicalPath mapped_path { string.substring_view(*split_index + 1) };
                             paths.append({move(host_path), move(mapped_path)});
                         } else {
-                            LexicalPath host_path { FileSystem::real_path(string).release_value_but_fixme_should_propagate_errors().to_deprecated_string() };
+                            LexicalPath host_path { FileSystem::real_path(string).release_value_but_fixme_should_propagate_errors().to_byte_string() };
                             LexicalPath mapped_path { string };
                             paths.append({move(host_path), move(mapped_path)});
                         }
@@ -477,7 +477,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                             stream.read_until_filled(buffer).release_value_but_fixme_should_propagate_errors();
                             argument_builder.append(StringView(buffer).trim_whitespace());
                         }
-                        dbgln("[wasm runtime] Stub function {} was called with the following arguments: {}", name, argument_builder.to_deprecated_string());
+                        dbgln("[wasm runtime] Stub function {} was called with the following arguments: {}", name, argument_builder.to_byte_string());
                         Vector<Wasm::Value> result;
                         result.ensure_capacity(type.results().size());
                         for (auto& result_type : type.results())
@@ -521,9 +521,9 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
         auto print_func = [&](auto const& address) {
             Wasm::FunctionInstance* fn = machine.store().get(address);
-            g_stdout->write_until_depleted(DeprecatedString::formatted("- Function with address {}, ptr = {}\n", address.value(), fn).bytes()).release_value_but_fixme_should_propagate_errors();
+            g_stdout->write_until_depleted(ByteString::formatted("- Function with address {}, ptr = {}\n", address.value(), fn).bytes()).release_value_but_fixme_should_propagate_errors();
             if (fn) {
-                g_stdout->write_until_depleted(DeprecatedString::formatted("    wasm function? {}\n", fn->has<Wasm::WasmFunction>()).bytes()).release_value_but_fixme_should_propagate_errors();
+                g_stdout->write_until_depleted(ByteString::formatted("    wasm function? {}\n", fn->has<Wasm::WasmFunction>()).bytes()).release_value_but_fixme_should_propagate_errors();
                 fn->visit(
                     [&](Wasm::WasmFunction const& func) {
                         Wasm::Printer printer { *g_stdout, 3 };
diff --git a/Userland/Utilities/watch.cpp b/Userland/Utilities/watch.cpp
index b1d57156eda..8065269865a 100644
--- a/Userland/Utilities/watch.cpp
+++ b/Userland/Utilities/watch.cpp
@@ -6,7 +6,7 @@
  */
 
 #include <AK/Assertions.h>
-#include <AK/DeprecatedString.h>
+#include <AK/ByteString.h>
 #include <AK/StringBuilder.h>
 #include <AK/Time.h>
 #include <AK/Vector.h>
@@ -53,7 +53,7 @@ static void teardown_tty()
     out("\e[?1047l\e[u");
 }
 
-static DeprecatedString build_header_string(Vector<DeprecatedString> const& command, Duration const& interval)
+static ByteString build_header_string(Vector<ByteString> const& command, Duration const& interval)
 {
     StringBuilder builder;
     auto interval_seconds = interval.to_truncated_seconds();
@@ -61,16 +61,16 @@ static DeprecatedString build_header_string(Vector<DeprecatedString> const& comm
     builder.appendff("Every {}.{}s: \x1b[1m", interval_seconds, interval_fractional_seconds);
     builder.join(' ', command);
     builder.append("\x1b[0m"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
-static DeprecatedString build_header_string(Vector<DeprecatedString> const& command, Vector<DeprecatedString> const& filenames)
+static ByteString build_header_string(Vector<ByteString> const& command, Vector<ByteString> const& filenames)
 {
     StringBuilder builder;
     builder.appendff("Every time any of {} changes: \x1b[1m", filenames);
     builder.join(' ', command);
     builder.append("\x1b[0m"sv);
-    return builder.to_deprecated_string();
+    return builder.to_byte_string();
 }
 
 static void handle_signal(int signal)
@@ -93,7 +93,7 @@ static void handle_signal(int signal)
     exit(exit_code);
 }
 
-static int run_command(Vector<DeprecatedString> const& command)
+static int run_command(Vector<ByteString> const& command)
 {
     Vector<char const*> argv;
     argv.ensure_capacity(command.size() + 1);
@@ -135,8 +135,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 {
     TRY(Core::System::pledge("stdio proc exec rpath tty sigaction"));
 
-    Vector<DeprecatedString> files_to_watch;
-    Vector<DeprecatedString> command;
+    Vector<ByteString> files_to_watch;
+    Vector<ByteString> command;
     Core::ArgsParser args_parser;
     args_parser.set_stop_on_first_non_option(true);
     args_parser.set_general_help("Execute a command repeatedly, and watch its output over time.");
@@ -166,7 +166,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::sigaction(SIGTERM, &quit_action, nullptr));
     TRY(Core::System::sigaction(SIGINT, &quit_action, nullptr));
 
-    DeprecatedString header;
+    ByteString header;
 
     auto watch_callback = [&] {
         // Clear the screen, then reset the cursor position to the top left.
diff --git a/Userland/Utilities/wc.cpp b/Userland/Utilities/wc.cpp
index 28a45fd0da6..21f74502f59 100644
--- a/Userland/Utilities/wc.cpp
+++ b/Userland/Utilities/wc.cpp
@@ -5,8 +5,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/DeprecatedString.h>
 #include <AK/Vector.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/File.h>
diff --git a/Userland/Utilities/xargs.cpp b/Userland/Utilities/xargs.cpp
index cb7da7e58ff..2db2df3539d 100644
--- a/Userland/Utilities/xargs.cpp
+++ b/Userland/Utilities/xargs.cpp
@@ -28,9 +28,9 @@ bool read_items(FILE* fp, char entry_separator, Function<Decision(StringView)>);
 
 class ParsedInitialArguments {
 public:
-    ParsedInitialArguments(Vector<DeprecatedString>&, StringView placeholder);
+    ParsedInitialArguments(Vector<ByteString>&, StringView placeholder);
 
-    void for_each_joined_argument(StringView, Function<void(DeprecatedString const&)>) const;
+    void for_each_joined_argument(StringView, Function<void(ByteString const&)>) const;
 
     size_t size() const { return m_all_parts.size(); }
 
@@ -44,10 +44,10 @@ ErrorOr<int> serenity_main(Main::Arguments main_arguments)
 
     StringView placeholder;
     bool split_with_nulls = false;
-    DeprecatedString specified_delimiter = "\n"sv;
-    Vector<DeprecatedString> arguments;
+    ByteString specified_delimiter = "\n"sv;
+    Vector<ByteString> arguments;
     bool verbose = false;
-    DeprecatedString file_to_read = "-"sv;
+    ByteString file_to_read = "-"sv;
     int max_lines_for_one_command = 0;
     int max_bytes_for_one_command = ARG_MAX;
 
@@ -121,7 +121,7 @@ ErrorOr<int> serenity_main(Main::Arguments main_arguments)
         if (items_used_for_this_command == 0) {
             child_argv.ensure_capacity(initial_arguments.size());
 
-            initial_arguments.for_each_joined_argument(item, [&](const DeprecatedString& string) {
+            initial_arguments.for_each_joined_argument(item, [&](const ByteString& string) {
                 total_command_length += string.length();
                 child_argv.append(strdup(string.characters()));
             });
@@ -198,7 +198,7 @@ bool run_command(Vector<char*>&& child_argv, bool verbose, bool is_stdin, int de
     if (verbose) {
         StringBuilder builder;
         builder.join(' ', child_argv);
-        warnln("xargs: {}", builder.to_deprecated_string());
+        warnln("xargs: {}", builder.to_byte_string());
     }
 
     auto pid = fork();
@@ -236,7 +236,7 @@ bool run_command(Vector<char*>&& child_argv, bool verbose, bool is_stdin, int de
     return true;
 }
 
-ParsedInitialArguments::ParsedInitialArguments(Vector<DeprecatedString>& arguments, StringView placeholder)
+ParsedInitialArguments::ParsedInitialArguments(Vector<ByteString>& arguments, StringView placeholder)
 {
     m_all_parts.ensure_capacity(arguments.size());
     bool some_argument_has_placeholder = false;
@@ -260,12 +260,12 @@ ParsedInitialArguments::ParsedInitialArguments(Vector<DeprecatedString>& argumen
     }
 }
 
-void ParsedInitialArguments::for_each_joined_argument(StringView separator, Function<void(DeprecatedString const&)> callback) const
+void ParsedInitialArguments::for_each_joined_argument(StringView separator, Function<void(ByteString const&)> callback) const
 {
     StringBuilder builder;
     for (auto& parts : m_all_parts) {
         builder.clear();
         builder.join(separator, parts);
-        callback(builder.to_deprecated_string());
+        callback(builder.to_byte_string());
     }
 }
diff --git a/Userland/Utilities/xml.cpp b/Userland/Utilities/xml.cpp
index c6e82ee31b4..b4fddd64744 100644
--- a/Userland/Utilities/xml.cpp
+++ b/Userland/Utilities/xml.cpp
@@ -289,7 +289,7 @@ static void dump(XML::Document& document)
                                     color(ColorRole::Tag);
                                     out("{} ", declaration.name);
                                     declaration.definition.visit(
-                                        [](DeprecatedString const& value) {
+                                        [](ByteString const& value) {
                                             color(ColorRole::AttributeValue);
                                             out("\"{}\"", value);
                                         },
@@ -320,7 +320,7 @@ static void dump(XML::Document& document)
                                     color(ColorRole::Tag);
                                     out("{} ", declaration.name);
                                     declaration.definition.visit(
-                                        [](DeprecatedString const& value) {
+                                        [](ByteString const& value) {
                                             color(ColorRole::AttributeValue);
                                             out("\"{}\"", value);
                                         },
@@ -362,8 +362,8 @@ static auto parse(StringView contents)
         contents,
         {
             .preserve_comments = true,
-            .resolve_external_resource = [&](XML::SystemID const& system_id, Optional<XML::PublicID> const&) -> ErrorOr<DeprecatedString> {
-                auto base = URL::create_with_file_scheme(s_path.to_deprecated_string());
+            .resolve_external_resource = [&](XML::SystemID const& system_id, Optional<XML::PublicID> const&) -> ErrorOr<ByteString> {
+                auto base = URL::create_with_file_scheme(s_path.to_byte_string());
                 auto url = URLParser::basic_parse(system_id.system_literal, base);
                 if (!url.is_valid())
                     return Error::from_string_literal("Invalid URL");
@@ -372,7 +372,7 @@ static auto parse(StringView contents)
                     return Error::from_string_literal("NYI: Nonlocal entity");
 
                 auto file = TRY(Core::File::open(url.serialize_path(), Core::File::OpenMode::Read));
-                return DeprecatedString::copy(TRY(file->read_until_eof()));
+                return ByteString::copy(TRY(file->read_until_eof()));
             },
         },
     };
@@ -383,7 +383,7 @@ enum class TestResult {
     Failed,
     RunnerFailed,
 };
-static HashMap<DeprecatedString, TestResult> s_test_results {};
+static HashMap<ByteString, TestResult> s_test_results {};
 static void do_run_tests(XML::Document& document)
 {
     auto& root = document.root().content.get<XML::Node::Element>();
@@ -402,7 +402,7 @@ static void do_run_tests(XML::Document& document)
 
     dump_cases(root);
 
-    auto base_path = LexicalPath::dirname(s_path.to_deprecated_string());
+    auto base_path = LexicalPath::dirname(s_path.to_byte_string());
 
     while (!suites.is_empty()) {
         auto& node = *suites.dequeue();
@@ -430,7 +430,7 @@ static void do_run_tests(XML::Document& document)
                 path_builder.append(entry);
                 path_builder.append('/');
             }
-            auto test_base_path = path_builder.to_deprecated_string();
+            auto test_base_path = path_builder.to_byte_string();
 
             path_builder.append(suite.attributes.find("URI")->value);
             auto url = URL::create_with_file_scheme(path_builder.string_view());
diff --git a/Userland/Utilities/zip.cpp b/Userland/Utilities/zip.cpp
index 841bf5dd274..07793ba29b5 100644
--- a/Userland/Utilities/zip.cpp
+++ b/Userland/Utilities/zip.cpp
@@ -50,7 +50,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     Archive::ZipOutputStream zip_stream(move(file_stream));
 
     auto add_file = [&](StringView path) -> ErrorOr<void> {
-        auto canonicalized_path = TRY(String::from_deprecated_string(LexicalPath::canonicalized_path(path)));
+        auto canonicalized_path = TRY(String::from_byte_string(LexicalPath::canonicalized_path(path)));
 
         auto file = TRY(Core::File::open(path, Core::File::OpenMode::Read));
         auto stat = TRY(Core::System::fstat(file->fd()));