There are three basic types of squats and many variations thereof throughout the athletic world. Because this skill / exercise is so ubiquitous, I thought that a simple picture presentation would be best. The three basic squats are Yoga Squat, Gymnastics Squat, and General Exercise Squat.
The Yoga Squat is more of a resting pose for someone who has great flexibility in the ankles and hips and good quadricep strength. This pose is used at the mid point of the Moon Salutation, as a place to rest and breathe deeply before finishing the routine.
The Gymnastics Squat is more of a preparatory position for starting forward rolls and backward rolls, or for teaching a gymnast what it feels like to be in a tight tuck for somersaults.
We use the General Exercise Squat for strengthening our quadriceps, and can be done with or without weights.
There are many more sports that I missed in pictures like hockey, speed skating and downhill skiing. And I'm sure many more that I've not mentioned, but you get the picture.
Aside from the squatting action or position of our hips and legs being fundamental in almost every sport, we do it everyday, many times a day when we sit in a chair or get up out of one. Hence, the Squat is so important and so widely talked about among exercise and fitness professionals and enthusiasts alike.