Tackles quads, glutes, hip flexors, and shoulders; abs and low back assist, so they benefit, too!
Grab a medium-heavy weight for this exercise. I often use 10-15 lbs.
Of course, you can also do this exercise with a kettlebell, and call it by its better-known title, the kettlebell swing, but I wanted to show that this can work either way.
Sit back into a deep squat, aiming to get down to about a 90 degree angle from the knees, and keeping weight behind you and off the fronts of your knees.
Swing the weight down through your legs, and as you come up, swing it back up to perpendicular from your body. Use your hips to almost thrust out as you come up, contracting your glutes at the same time.
Repeat this as quickly as you can while maintaining form for about 15 (beginner) to 25 (advanced) reps.