What is the exercise for muscle in the legs?

Two good exercises to build leg muscles can be done with or without added weights: 1) Squats: Legs are shoulder width apart. Lower backside as if sitting in a chair. Keep knees above toes, not past them. Watch that the legs/knees do not stray to the sides. 2) Lunges: Hands on hips, straight back. Take a step forward, and lower opposite knee/shin almost to the floor, as if kneeling. Front shin stays upright, bent at the knee. Both legs should form 45-degree angles. Return to original position, and repeat with opposite leg. These exercises use all the big muscle groups in the legs at once.