I'm going to ignore the obvious bashing and get to the point.
A compressor, in it's basic use, does get the "heat" of of some tracks, and can be used for limiting (ie, when you're goign to tape, in order to prevent clipping).
But a compressor has thousands of uses. In fact, I'd almost say that compressors are the most used effect in a studio.
There are numerous articles on how to use compressors effectivley- I'll try and dig up a couple, but try
www.soundonsound.com - i vaugely remeber them having a good intro teh the compressor.
You can do all sorts of things withproper compressor technique- you can add sustain to an instrument, or, conversly, "sharpen" an instrument up so that it stands out in the mix.
you can use light compression to minimise the level change caused by a vocalist moving to and from the mic, or you can use it to get a bit more warmth out of a piano.
It's really too vast a topic to cover in a single post, and, like most art, you'll find you get the best results when you play around a bit.
I suggest buying a compressor that has a couple of presets built in- I have a couple of Presonus Bluemaxes, and I love them to death. They have about 15 presets for different instruments, and, by listening to those, you can hear the difference that a compressor can make.
Finally, a bit of bashing (I can't help myself).
There are a lot of people here that are willing to help, if you want it. Sure, you might think it's funny to name a thread something stupid, but you can't then expect a serious answer.
Conversley, if people are titling threads in a stupid manner (well, not this stupidly, but you get me) or behaving immaturely, it's up to us to set the bounds, but not in a way that will scare off new users. Unless they really deserve it...
Really, what were you thinking Irk?