Character encoding defines a mapping between bytes and text. A sequence of bytes allows for different textual interpretations. By specifying a particular encoding (such as UTF-8), we specify how the sequence of bytes is to be interpreted.

XML specifies five predefined entities needed to support every printable ASCII character: & , < , > , ' , and " . The trailing semicolon is mandatory in XML (and XHTML) for these five entities (even if HTML or SGML allows omitting it for some of them, according to their DTD).

Character encoding The most popular is UTF-8, where the ASCII characters, such as English letters, digits, and some other common characters are preserved unchanged against ASCII. This makes HTML code (such as <br> and </div>) unchanged compared to ASCII. Characters outside the ASCII range are stored in 2–4 bytes.

UTF-8 is a variable-length character encoding standard used for electronic communication. Defined by the Unicode Standard, the name is derived from Unicode Transformation Format – 8-bit. UTF-8 is capable of encoding all 1,112,064 valid Unicode code points using one to four one-byte (8-bit) code units.