This is something I never thought about too much but have played with a bit over the years. I naturally squat sorta narrow (stance about shoulder width apart) . This is because I have a somewhat small waist and hips and I am considered a leg squatter. Other guys who have a bigger waist/hips are more glute and hamstring squatters. They can typically ( not always and I am just basing this from the average gym rat) squat more then the leg squatter. After watching some PL's with much wider bases put up some serious weight I tried to convert over to a wider stance. It just didn't work for me and it made more sense and I felt more comfortable and stronger with my normal shoulder width stance. So.......the point: if you are new to the squat choose the stance that best suits your frame.