HTML versions

There are currently four major versions of HTML and XHMTL:


 * HTML 4.01
 * XHTML 1.0
 * XHTML 1.1, including XHTML Modules
 * XHTML 2

XHTML 1 is basically the same as HTML 4, and does not add or change elements. The big change is that XHTML 1 uses a valid XML format, and XHTML 1.1 splits the specification in seperate modules.

MIME Type
Unfortunately, Internet Explorer does not support the correct XHTML 1 MIME Type: application/xhtml+xml, and so most authors write in XHTML, but specify the HTML 4 MIME-type (text/html). While the W3C validator accepts the results, it is formally invalid. Strangely, Internet Explorer does accept the application/xml MIME Type.

My recommended solution is to have the webbrowser serve Content-Type: text/html And put in each individual webpage 