In SGML (standard generalized markup language) and its descendants, such as HTML (hypertext markup language) and XML (extensible markup language), the ampersand is used to begin the encoding that represents a special character (i.e., a character that is not included in the limited standard character set), and such encoding is terminated with a semicolon.

For example, the HTML encoding for the at symbol (@) so that it will render correctly in a web browser is @, and the encoding for the copyright symbol (©) is ©. The ampersand can be encoded with a choice of & and &#amp;.