XHTML is a markup language that is based on existing document types.
It is much more flexible than its predecessor HTML and can reproduce, subdivide and extend it.
XHTML makes it possible to integrate future modules and devices with limited display options, such as handhelds, mobile phones or palmtops, as browser-enabled end devices to display content from the web.
It is also compliant with XML, which means that one can easily validate, view and edit such documents with standard XML tools.
In principle, XHTML documents can use applications that depend on either the XML or HTML document object models.