Puberty denotes the biological changes that take place in children's bodies, turning them into mature, adult bodies with the ability to procreate. Puberty begins when the pituitary gland in the brain begins to produce larger quantities of Follicle Stimulating Hormone (FSH). This, in turn, causes boys' testes to produce testosterone, and girls' ovaries to produce estrogen.
Puberty can begin as early as 7 for girls and 8 for boys, although in most cases it starts some years later. Each child progresses through puberty at his or her own rate, but since pubertal development is influenced by genetics, members of the same family may follow similar patterns. The entire process can take between a year and eight years, although four or five is the norm.
The stages of puberty for girls and boys are similar. Pubic hair begins to grow around the genitals, and some time later underarm hair sprouts too. Adolescents go through a series of growth spurts during puberty, becoming taller and heavier and developing a mature body shape. They may experience a stage of awkwardness when the hands and arms, and feet and legs are growing more quickly than the rest of the body. Both boys and girls begin to sweat more, and most go through a stage of having oily skin, which can cause pimples or acne.
Boys' larynxes grow, causing their voices to deepen (often after a time of "breaking" when the voice is unsettled) and an Adam's apple to appear. Sperm starts to be produced and they begin to experience erections and wet dreams. They grow facial hair. Girls develop breasts and begin to ovulate and menstruate. Both boys and girls generally attain their full adult body by the time they are 18.
The extra hormones in the body can cause mood swings, irritability and anger as the body adjusts to the changes it is going through. These, like the physical changes, will pass as the body and mind mature.