HTML 5 versus XHTML 1.0 Transitional?

Question

It seems that HTML 5 is going to be supported (partially) by Firefox 3.1 and other browsers. It is adding support for video and audio as tags, but these are new tags that XH

Answer 1

Your doctype will tell the browser whether you're using HTML5 or XHTML. You can't just shove a tag from one doctype into a document of another doctype and expect it to work. Without a doctype, it's all just tag soup anyway.