Puberty begins at different ages for boys and girls ,on average. According to the American Academy of Family Physicians, puberty begins for girls between 8 and 14 years of age. For boys, the average is between 9 and 14 years. The stages of puberty are denoted by the advance of pubic hair for both boys and girls. For boys, the size of testicles is used to gauge the advance of puberty, and for girls, the size and contour of breasts are used.

Stage One

The first stage of puberty is actually a starting point. There is no sexual development in boys or girls in the first stage of puberty. Also, pubic hair has not yet appeared.

Stage Two

In the second stage of puberty, boys will develop a body odor and experience an enlargement of testicles. For girls, there is the first appearance of public hair, the body develops a body odor, the breasts begin to bud and there is a sudden growth in height.

Stage Three

The third stage of puberty is marked for boys by an enlargement of the penis, the growth of pubic hair and ejaculation, or wet dreams. The third stage is marked for girls by an enlargement of breasts, vaginal discharge and a darkening of public hair. For girls, pubic hair also begins to become curlier.

Stage Four

For boys, the penis and testes continue to enlarge in the fourth stage of puberty. There is a deepening of color of the penis and scrotal sac. There is also a spurt in height. Girls experience the onset of menstruation in the fourth stage of puberty ,as well as the development of a distinction between the nipple and the areola.

Stage Five

For both boys and girls, the fifth stage of puberty is marked by pubic hair extending to the inner thighs. Growth in height slows and eventually stops. The fifth stage of puberty is considered fully mature adulthood.