Extensible Hypertext Markup Language, abbreviated as XHTML, is a general purpose language created to represent documents for an extensive range of purposes across the world wide web (WWW). It is a more confining subset of Standard Generalized Markup Language (SGML) and belongs to the family of XML markup languages. It replicates or extends versions of the commonly used HTML.
In simple words, while using XHTML, you are basically writing an XML code, limiting yourself to a predetermined set of elements. This provides authors with all the advantages of an XML, while preventing the complications of true XML.
In fact, a well-written XHTML page is more accessible compared to an old style HTML page. It allows greater access to configurations other than a PC and browser.
It works on the agenda of less presentation, less scripting, and more structure.
It is backward compatible.
It features more usability and accessibility.
It is device independent.
It easily integrates with the semantic web.
Any element can be the source of a hyperlink.
It treats the image and the texts as equivalents.
Any element in XHTML2 may have source attribute.
It uses XML events to specify event handling.
The frame model is defined through the separate specification.