Although we’re now in this transitional stage of shedding off old browsers and web technologies that have been stumbling blocks to creating innovative new websites, there’s still confusion and fear that needs to be quelled. (Some people just can’t get excited that easily.)
Jeremy Keith’s article, Misunderstanding markup, seems like the ideal anchor at this point. First, it points out the differences between XHTML 1.0, XHTML 1.1, and XHTML 2:
- XHTML 1.0 = HTML4 with XHTML syntax
- XHTML 1.1 = XHTML 1.0 with the requirement that documents should be served with the XML MIME type
- XHTML 2 = a whole new specification that has little in common with XHTML 1.0/1.1/HTML 4
- XHTML has two types: pages that are actually served using the
application/xhtml+xmlMIME type; and pages that are actually served using thetext/htmlMIME type but follow XHTML syntax.
Confusion? Fixed.
Second and more importantly, it emphasizes what the triumph of HTML5 means for XHTML:
- You can still use XHTML syntax on HTML5 documents; it’s flexible enough and backwards-compatible (unlike XHTML2) that way. You can also go back to old coding conventions like uppercase tag names, optional quoting of attributes, and the absence of trailing slashes, and that’s okay too.
- In fact, you can serve HTML5 documents as
application/xhtml+xmland you get an XHTML document, affectionately called XHTML5. At this point, only XHTML2 is dead. - Still scared about taking the plunge to HTML5? It’s as easy as replacing that long-winded strict, transitional, or (gasp) frameset DOCTYPE declaration to
<!DOCTYPE html>.
Once you learn items 1 and 2, the third item is all you’ll need to focus on from now on. It’s a comforting message that if you think catching up to HTML5 will be difficult, rest assured that it’s not as scary as it looks.
Fear? Fixed.
Let’s move on, shall we?

does this mean that i can jump onto HTML5 today?
[^^]
xun, sure you can jump onto HTML5, but you can also write your xHTML code inside of new HTML5. Here I have found and posted a comic strip about understanding how xHTML will work in new HTML:
http://www.manakor.org/xhtml/what-markup-language-to-use-now-xhtml-2-or-html-5
I still code everything in HTML 4.01