What is XHTML?

On November 17, 2008

On January 26, 2000, the great W3C shocked us that HTML 4 has been reformulated into XHTML 1.0. XHTML is HTML 4 written as an XML application.

We can divide XHTML in to two parts:

HTML 4
HTML 4 is a markup language used for displaying contents and documents across different platforms and machines. It was originally intended for a very specific audience, and has expanded to include hypertext, multimedia, as well as the style of the documents displayed.
XML
XML is an extensible markup language that was developed to retain the flexibility and power of HTML while reducing most of the complexity.

Actually XHTML combines the flexibility of HTML with the extensibility of XML. Confuse? Keep Reading….

HTML tags that are only viewable in one browser or another. Some of these tags had been brought into the HTML 4.0 DTD, and others had not, but the result of using these tags is that your pages will never look the same in all browsers. The only solutions that an HTML writer has are: not use those tags, use those tags and state that the page is meant for one browser or another, or write multiple pages and use scripting techniques to direct readers to the appropriate pages or detect browsers.

But with XHTML this is not necessary. With XHTML, if you find a need for a new markup tag, you simply define it in an XHTML module and use it in your page as you would any other HTML tag. You can also use XHTML to markup the code as appropriate for the (XHTML compatible) browser that is viewing it.

Inspired by: Jennifer Kyrnin at About.Com