The skeletal system is composed of bones, cartilage, joints and ligaments. It provides structure and support to the body, protects internal organs, allows for movement via muscle attachment, and stores minerals. The bones are classified as long, short, flat, or irregular. Key bones include the skull, vertebral column, ribs, shoulder girdle, pelvis and bones of the upper and lower limbs. The skeletal system enables vital body functions and works with muscles for movement.