extensible hypertext markup language (XML) (XHTML)
Extensible HypertextMarkup Language (XHTML) is a markup language based on XML that is intended to replace Hypertext Markup Language( HTML). XHTML relies on existing document types, is much more flexible than HTML, is also fault-tolerant, and can incorporate future modules.
XHTML, which has been described by the World Wide Web Consortium(W3C), also allows devices with limited display capabilities, such as cell phones, handhelds, and palmtops, to display Web content as browser-enabled devices.
XHTML, which is compatible with HTML 4.0, provides for the consistent application of prescribed syntax rules. The "X" of XHTML, which stands for Extensible, gives web designers greater design options by including their own tags in an XHTML document.