What is up with all the AP H.S. courses now? Are they really necessary to get into a good college?

It seems every parent I know tells me about their kid taking a bunch of AP courses and I guess I don't understand why that is necessary. Don't the H.S.'s have advanced courses available as part of their normal college tract course offerings? I mean like chemistry, physics, alg II, geometry, trig, etc? That is all I took back in the day and I was able to score high enough on my SAT's to get into University of Florida, College of Engineering....so fill me in on what is happening out there now days. I have a 12 year old son who is taking an offered advanced math (basically it is 7th grade math in 6th grade) now but I'm not sure I see a boatload of AP classes in his future.