The flood of college mail- What does it mean?

After I took the PSAT sophomore year I started getting a few letters from colleges, the general tone being, "Hey, you did pretty good on the PSAT. Come look at our college!" I was thinking it was pretty cool. Who doesn't love getting letters addressed to them? As long as they're not bills, that is. Junior year I took the PSAT again, the ACT and the SAT, and I did pretty well on all three. All of a sudden, there is college mail everywhere, from colleges I've never even heard of! Not only are there letters, but there are view books, extolling the virtues of a higher education at their institution. I have a whole basketful of mail just from colleges, but what does all of it really mean?
Each college really says the same thing about themselves, that you will get an excellent education if you go to their school and that you'll be successful in life. OF course, there's no way that they can guarantee that. The true purpose of colleges and universities in sending mail seems to be just to get on your college radar. It's helped me to find various places that I may apply to, but don't be fooled by the cool designs on a view book. The information they send you is very helpful, but it's a very shallow look at a place you will be spending four years of your life at, and that definitely merits more in-depth research.