Extensible Hypertext Markup 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 error-tolerant
, and can incorporate future modules. XHTML, described by the World Wide Web Consortium (W3C), allows devices with limited display capabilities, such as cell phones, handhelds, and palmtops
, todisplay 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, offers web designers greater design options by introducing their own tags into an XHTML document.