Puberty
Puberty is what happens in children's bodies that changes them into adults. Puberty usually takes about four or five years. However, when most people say "going through puberty", they usually just mean approximately the first two years. After that, people sometimes use the word adolescence, although that is a not a very precise word. As girls and boys go through puberty, they become able to have sexual intercourse (sex) and produce children of their own. A girl can become pregnant and have a baby. During puberty, a boy's body begins making semen, and he starts to be able to ejaculate, which is semen shooting out from his penis when he is sexually excited. If he has sex with a girl, meaning he puts his penis into her vagina and ejaculates in her, he can make her pregnant.