HTML is the language of the web, what webpages are written in. There's so much out there I don't feel I can say anything that hasn't been said many times already.
These webpages have the property that if you widen the browser window the webpage itself remains centred in the window. Narrow the browser window and the webpage will stay centred until it is wider than the window in which case you'll have to scroll the browser window. The webpage itself stays a fixed size. I like this behaviour and achieve by having a centered DIV element which is relatively positioned and has a set width. Inside the DIV can be absolutely positioned elements or a centred TABLE.
So the HTML is like:
<HTML> <BODY> <CENTER> <DIV STYLE="width: 800; position: relative"> ... </DIV> <CENTER> </BODY> </HTML>
It's not fashionable but I use TABLE a lot for layout. I just find them easier for me to work with. Your mileage may vary.