Originally Posted by Teger
I actually squat pretty low - imagine in a normal power cage, if you have the adjustable bars at the lowest area (the two pieces that catch a dropped weighted bar) - I'm squatting to 3-4 inches above that
Trying to go too low was how I injured myself, too, because that forced my knees to move forward to get that kind of depth. If you have the flexibility to go low while maintaining good form, then go for it.
The goal of squatting below parallel is to recruit your posterior chain (hamstrings and butt muscles) when you start standing up again, and not hurt your knees (because the quads and hamstrings are pulling in opposite directions on the knee), assuming you are driving up from the hips. It is possible to go too low, and lose tension in the muscles you're trying to strengthen, like the hamstrings, so you may end up not doing good work, and maybe hurting yourself.