HTML5 Backwards Compatibility

OK so I understand that HTML5 supports the existing markup (HTML + XHTML). This is great. However, what happens when I want to use any of the new HTML5 tags?
http://www.w3schools.com/html5/html5_reference.asp

If I want my website to work properly in IE6 should I avoid using any of the new HTML5 tags?
(Just for the record, which browsers currently support HTML5 and CSS3, and which ones do not? Are there tried and true fallback methods for those older browsers?)

Thanks,

You’ll probably see those tags lying on page with other contents.

I’m afraid so.

Well, latest versions of any major browser should be compatible with HTML5 and CSS3. However, that doesn’t mean they will support all the features of HTML5 and CSS3.

Most proposed features of HTML5 and CSS3 are not supported in browsers yet, but you can experiment with a few. There are style sheets and scripts written for older browsers that help them recognize some of the newer elements. For example, you can use the html5shiv together with css [URL=“http://necolas.github.com/normalize.css/”]normalize to help browsers cope with them. Or yo can use [URL=“http://modernizr.com/”]Modernizr.

Personally, though, all this seems like it’s jumping the gun and abandoning the principles of graceful degradation / progressive enhancement, as you end up replying of JS/CSS for content to be available, which is a kind of heresy.