Hi everyone,
I am reading this book for the second time and it is equally as interesting as the first time: http://www.abookapart.com/products/h...-web-designers

What I am wondering about is this:

Browser makers are the ones who decide which markup to support, so for HTML5 it's about supporting anything and everything to make it the easiest on everyone. Rather than discontinuing old coding practices and try to force the change to something "new and better" (which is what XHTML 2 tried to do but failed) the browser makers will do their best to support everything.

I guess this is where my knowledge of who's role does what get's a bit foggy when it comes to HTML advancements, W3C, WHATWG, and the browser makers themselves. I understand that XHTML 1.0 is a "coding practice", or a style of writing code that is a good one. Close all tags, write in lower case, include quotes - it seems like a good way to go.

So when I change my code from <script type="javascript" src="javascript.js"> to just be <script src="javascript.js"> this is now using the new(?) HTML5 syntax, which is simplified and leaner. Good...
How will IE6 render this code? Will it have any problems with it? If it doesn't have problems with it, and this may sound like a silly question, but how come we haven't been using this syntax from the very beginning when IE6 first came out?

Also, when it comes to doctypes... the simplistic HTML5 doctype "<!DOCTYPE html>" works in all browsers too? Again, if it works in all browsers (old and new) then how come we have been using the messy long "XHTML / W3C" doctypes all this time before HTML5?

I am also getting the hunch that HTML5 code syntax is nothing ground breakingly "new", in fact we have already been using it all this time? It's now up to us which coding practices we wish to use and follow through with. So why do we put a new version number on "HTML5", is it to give it the appearance that it's something new?

Also, if we adopt these leaner, more simplified HTML5 coding practices that I mentioned above it break anything when it comes to the older browsers, such as IE6? And if the old browsers already fully support this code practice then how come we haven't been using the leaner, more simplified code to begin with when IE6 first came out? :P

Hope my questions make sense - I'm just trying to wrap my head around how and why the code syntax for HTML version advancements that W3C pushed forth were so confusing in the past, how W3C / WHATWG is rectifying this problem in the future, and how these changes effect the rendering engines when it comes the older browsers.

Also, which older browsers do not currently support the <script src="javascript.js"> tag, or the <!DOCTYPE html> tag? (Two examples that come to mind) - And if these older browsers do not render these tags at all, can they still load up the Javascript or render the rest of the HTML in the page?