What is XHTML?

The evolution of HTML has essentially stopped. Instead, HTML is being replaced by a new language, called XHTML. XHTML is in many ways similar to HTML, but is designed to work with the new eXtensible Markup Language, or XML, that will soon serve as the core language for designing all sorts of new Web applications, in which XHTML will be only one of many "languages." But, XHTML is designed to work with these other language, so that different documents, in different languages, can be easily mixed together.