Escape Sequence

An escape sequence is a character or group of characters inside a string literal that represents a different character than it literally looks like. The most common form is a backslash followed by a letter or digits: \n represents a newline, \t represents a tab, \" represents a literal double quote that does not close the string.

JSON’s escape sequences

JSON defines a small, fixed set of backslash escapes:

Escape	Meaning
\"	Double quote
\\	Backslash
\/	Forward slash (optional)
\b	Backspace
\f	Form feed
\n	Line feed
\r	Carriage return
\t	Tab
\uXXXX	Unicode character by 4-hex-digit code point

Any other backslash sequence (\x, \0, \a, \e) is an error. The spec is strict about this, and strict parsers will reject unrecognised escapes.

Surrogate pairs

For Unicode code points above U+FFFF — including every emoji — JSON uses UTF-16 surrogate pairs: two consecutive \uXXXX escapes, a high surrogate (\uD800-\uDBFF) followed by a low surrogate (\uDC00-\uDFFF). 😀 (U+1F600) is encoded as 😀.

Why escape sequences exist at all

A string literal has to start and end with the same character (double quote in JSON). If you want to include a literal double quote inside the string, the parser needs a way to tell it apart from the terminating quote. Escape sequences are that way.

The same problem applies to:

• Backslash itself (the escape character).
• Control characters (tabs, newlines) that would break the line structure of the serialised form.
• Any character that could confuse a downstream processor.

Escape sequence vs. HTML entity

Both are ways to represent characters symbolically. They are not interchangeable:

• JSON escapes: \n, \", \uXXXX. Work in JSON strings only.
• HTML entities: &, <, ©. Work in HTML/XML element content and attribute values only.

If you see & in a JSON string, you have the literal six characters &, a, m, p, ; — not an ampersand. If you see \n in an HTML attribute, you have the literal two characters \ and n — not a newline.

Common mistakes

• Forgetting to double backslashes in Windows paths: "C:\Users\..." must be "C:\\Users\\...".
• Assuming \x41 (hex escape) works in JSON — it does not. Use A.
• Using HTML entity syntax inside JSON strings.
• Mixing up \r\n on Windows — JSON tools generally normalise to \n, which is what the spec actually requires for newlines.

See the guide Escaping strings in JSON for the full reference with language-specific quirks.