The document discusses the human muscular system. It notes that humans have over 600 muscles that are flexible and give strength, allowing for lifting, pulling and movement. Muscles are either involuntary, like those in the eyes, stomach and uterus which cannot be controlled, or voluntary like those in the face, arms and legs which are controlled by the brain sending messages to contract or relax. It then names and describes some major voluntary muscles like the biceps, quadriceps, abdominals, gluteus, pectorals and deltoids, and their functions. The document concludes by emphasizing the importance of daily exercise for keeping muscles healthy and strong.