Puberty is a normal stage of human development when the body starts developing adult features and reproductive organs become capable of reproduction. During puberty, glands produce large amounts of hormones that control growth, development, and reproduction. For boys, changes include growth spurts, development of body hair and an Adam's apple, active oil secretion, and wet dreams. For girls, changes include growth spurts, breast development, body hair growth, hip widening, and onset of menstruation. Menstruation involves monthly shedding of the uterine lining for around 3-5 days through a menstrual cycle that varies in length for each girl. Psychologically, adolescents experience changes in thinking, feelings, and social interactions as they develop their identity