Webmaster 101

The Extensible HyperText Markup Language, or XHTML, is a markup language that has the same depth of expression as HTML, but also conforms to XML syntax.

The difference is that while HTML is an application of Standard Generalized Markup Language (SGML), a very bendable or rather flexible markup language, XHTML is an application of XML, a more restrictive subset of SGML. Unlike HTML, which requires a relatively complex, lenient, and generally custom parser, true XHTML documents allow for automated processing to be performed using standard XML tools, because they need to be well-formed. XHTML can be said to be acombination of HTML and XML in certain regards, since it is nothing but a reformulation of HTML in XML.

Need for XHTML

World Wide Web content now needs to be delivered to many devices (like mobile phones etc.) apart from traditional computers, where additional resources cannot be devoted to support the added intricacy of HTML syntax. In reality, though, HTML-supporting browsers even for such limited devices have emerged faster than XHTML support has been added to the desktop browser..

Another aim for XHTML and XML was to bring down the demands on parsers and user agents in general. With HTML, user agents had to carry out the burden of “correcting” errant documents. The alternative that exists with XML is that it requires user agents to give a “fatal” error when encountering malformed XML. This means that at least in theory, an XHTML browser can omit error recovery code even though it may even need slightly more error detection checks.

XHTML is often considered the successor to HTML. In the general opinion, many already consider XHTML as the newest version of HTML. Having said that, XHTML is a separate recommendation by itself. The W3C continues to recommend the use of XHTML 1.1, XHTML 1.0, and HTML 4.01 for web publishing, and HTML 5 is currently being actively developed.

Filed under: HTML & XHTML