XHTML (Extensible HyperText Markup Language)
The Extensible HyperText Markup Language (XHTML™) is the successor to HTML, the original language of the World Wide Web. It consists of a family of current and future document types and modules that reproduce, subset, and extend HTML, reformulated in XML. XHTML family document types are all XML-based, and are designed to work in conjunction with XML-based browsers and other user agents. Specifications for XHTML have been developed by the W3C (http://www.w3.org/MarkUp/#recommendations). See also: HTML and XHTML Frequently Answered Questions and the Wikipedia Entry.