CSS footer that sticks to page bottom

What’s beautiful of about css is that you can literally set up all sorts of things with positioning for your page without changing the actual HTML. And changing HTML is super old school.
But with about fifteen lines of css by Ryan Fait, you can pretty much make a footer hug the bottom of the page and it seems to work with all browsers (which is very key in design work).
If you do some design work and have been searching for a little something to help you out, reading this code should help you understand a little about how css works and why this does the trick. Pretty much what it does is that it declares the page to be 100% height without the last portion of it. Then setting up the footer to fill the missing portion.