XML stands for Extensible Markup Language, a markup language that determines how to describe, share and store data. It works as a complement to the HyperText Markup Language or HTML markup language in Web development.
Whereas HTML dictates how data should appear in Web browsers, XML works in the background to handle and describe data. Web pages that utilize XML have data that are separate from their page layouts. This characteristic allows Web pages to dynamically change their contents without needing to modify their HTML code. By featuring user-defined, human-readable tags, XML also streamlines data transmission across platforms over the Internet. As a meta language, it is the basis of other languages such as MathML, RSS, SVG and XHTML.