XML (Extensible Markup Language)

A system for defining specialized markup languages that are used to transmit formatted data. Markup languages are the codes that are combined with text to tell the computer what format—boldface, italic, etc.—to present that text in. One of the best known markup languages is HTML, which is used to format Web documents. XML is related to HTML, but XML is not itself a markup language; it's a meta language, a language used to create other specialized languages.