I know this topic has been widely discussed so please don't clobber me guys! While I know things about the mechanics of a car, the electrical components of automotive vehicles is confusing to me. Could one of you please tell me what are LED lights for cars? I know that people put LED's to light up the car from the bottom with different colors, etc. But I do not like that stuff. Can the stock head lamps and tail lights be replaced with LEDs? If so, what is the purpose of this? Do any of you have before and after pics? Thanks!

-Sam