Primary Muscle Group: Legs
With the barbell on a rack, step under it so that it rests across the back of your shoulders, hold on to the bar to balance it, raise up to lift it off the rack, and step away. The movement can be done with your feet flat on the floor or your heels resting on a low block for support. Now keeping your head up and back straight, bend your knees and lower yourself until your thighs are just lower than parallel to the floor. From this point, push yourself back up to the starting position.
It is important to go below parallel in this movement, especially when you are just learning the exercise, so that you develop strength along the entire range of motion. If you don’t go low enough in the beginning you could injure yourself later when using heavier weight. Foot position to some extent determines which area of the thighs you work the most while doing Squats: a wider stance works the inside of the thighs to a greater degree, while a narrow stance tends to work the outsides more; toes turned out hits the inside of the thighs. The basics stance for greatest power is usually feet shoulder-width apart with toes turn slightly out.