How deep should you squat?  That depends on your goals, according to Loren Chiu and colleagues from the University of Alberta in Canada.  Deep squatting overloaded the quads and glutes better than parallel or partial squats and triggered more significant muscle activation.  Form often breaks down during deep squats.  When learning this exercise, hinge at the hips and maintain a neutral spine.  Avoid rounding the back and increase squat depth gradually.  The squat is one of the best exercises for bodybuilders and power athletes.  However, it can be among the most dangerous if performed incorrectly.  (Journal Strength Conditioning Research, 26:  2820, 2828, 2012)