His body becomes muscular and his penis and testes grow larger. His penis, when erect, can enter a woman's vagina to provide sperm from his testes to fertilize an egg. He grows hair on his face and body and his voice becomes deeper. Most boys and girls enjoy the process of growing up. They welcome the challenge of gradually becoming more independent and responsible for their own actions.
Sexual attractions begin to develop and friendships form with members of the opposite sex.
Young people can reproduce at the end of puberty. The age when this occurs varies but it nearly always happens before boys and girls have left school. In many countries there are laws governing the age when a young person may consent to sexual intercourse. In Britain the minimum age is 16. It is important to consider all of the possible consequences before engaging in sexual activity with another person.