For athletes, fitness enthusiasts and general exercises alike, squats should serve as the staple to a weight-training program. A compound exercise that targets all of the major muscles in the hips and legs, the squat offers more training benefits than any other exercise.

While exercises like leg extensions, leg curls and calf raises target specific leg muscles, squats hit all of the lower body muscles. Squats build strength in the glutes, quadriceps, hamstrings and quads. Depending on how many sets and reps you do and the weight you use, they can build used to build lower-body strength, size and power. Squats also build strength throughout the core, as your abdominals, obliques and lower back engage to keep your torso upright and taught throughout the exercise.

For lifters interested in building mass, incorporating squats into a training regimen has been shown to stimulate the release growth hormone and testosterone. Compared to other weight-training exercises, squats burn a significantly higher number of calories, which in turn helps to burn fat and support fat loss. Lastly, squats require the hips, knees and ankles to move through their complete range of motion to improve lower-body flexibility. This in turn helps reduce the risk of injury and lower back pain caused by inflexibility.

With all the fitness benefits of squats, there's no question that they should be the anchors of your weight training workouts. There are countless ways to perform the squats, but by mastering and incorporating these four into your regimen, you will quickly notice strength, tone, size, power and flexibility improvements in the hips and legs.

Standard Body-Weight Squat

It's important to first master the basic squat before moving onto more advanced variations. Stand with your feet set to hip-width apart and toes pointed straight ahead or slightly outward. Hold your arms out in front of you so that they're parallel to the floor. Begin the squat by first pushing your hips back. Then, bend your knees to drop your glutes toward the floor. Continue until your knees are bent to 90 degrees and your thighs are parallel to the floor, and then straighten your knees and hips to return to a standing position.

First do the exercise without using any weight, focusing only on getting down the technique. When you feel comfortable, try holding a pair of dumbbells down by your sides.

Wall Squat

Another good beginning squat exercise is the wall squat. The exercise is ideal for beginners, but can also be modified for advanced lifters. Stand with your back to a sturdy wall with your feet hip-width apart and your heels about a foot away from the floorboard. Lean back so that your back rests on the wall. Bend your knees to slide your back down the wall. Keep going until your thighs are parallel to the floor and then straighten your knees to slide your back up the wall and return to a standing position.

For a greater challenge, hold the down position of the squat for time. Keep your hands off your thighs and hold the position for as long as you can.

Single-Leg Pistol Squat

The single-leg pistol squat challenges each leg to work independently. Your one leg has to lift and lower your entire body weight on its own. Stand on one leg, with your free leg held slightly out in front of you. Hold your arms out in front of you so that they're parallel to the floor. Squat down to lower your hips toward the floor. If you can, keep going until your thigh is parallel to the floor. Depending on how low you go, you may need to lift your free leg upward as you do the squat. To rise back up, extend your hips and the knee of your working leg. Finish all reps on the one leg and then switch sides.

Goblet Squat

The goblet squat not only works the hips and legs, but also hits the upper back muscles. Holding a kettlebell at the front of your chest, elbows pointed at the floor, set your feet to hip-width apart. Keep the kettlebell in place as you push your hips back and bend your knees to drop into a squat. Continue until your elbows touch the insides of your knees and then extend your hips and knees to return to a standing position.