Stand up and place your feet a bit wider than your shoulder width. Cross your arms in front of you or simply keep them extended straight in front of you. This is your starting position.
Squat down all the way until your legs are bent at least 90 degrees. You can go even lower if you wish for a deeper squat. Then, push yourself back up with your legs and get in the starting position again.
Finally, repeat the entire movement for the desired or prescribed number of repetitions.
Perform this exercise in a smooth and fluid motion
Keep proper balance at all times; if you are having problems with your balance adjust your stance or slow down the movement
Don't hunch your back while performing this movement; keep your back straight and vertical at all times
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, slow down the movement or do barbell squats.
This exercise is ideal for beginners that want to build a strong foundation for doing weighted barbell squats at some point in the future. It allows for your leg muscles and joints to get used to the movement. Thus, after doing this exercise for a couple of months, you should move on to barbell squats. Once this happens, this body weight exercise will become a warm-up exercise for your weighted squats.
Another item worth a mention is the fact that when you perform squats using only your body weight, you can't really expect to build bigger legs. While most other body weight exercises (for other muscle groups) are effective in building muscles, this rule does not apply to the legs. Legs have some of the largest muscles on our body and to grow them bigger you need to work them under a considerable amount of weight. Using body weight exercises alone for your legs will not build massive quadriceps.