How do I know if my HTML is Correct

[sajiv]

It's good to validate your HTML. Just because you can see the Web page ok on your browser doesn't mean every browser will show it that way, or even be able to access the Web page. Browsers attempt to "work around" HTML errors, and the differences can be subtle or drastic.

That's why the folks at WC3 have worked up the specifications of what works for every browser. Although some may display it a little different, at least you know they can access your page. (The different browser programs have their own set of "whistles and bells" that just won't do the same... especially Microsoft Internet Explorer and Netscape Navigator.)