Adolescents reach the stage of puberty from as early as age 8 to about age 18. Everyone goes through puberty at different times.

During puberty, a girl will begin to develop breasts and hips, grow body hair under her arms and around her vulva, and will get her first menstrual period.

A boy will begin to grow body hair under his arms, as well as around his penis. He will begin to develop more muscle in his upper body, his voice will begin to deepen, and he will start producing semen. These changes may seem strange at first, but they are completely normal.

Most women begin menstruating (having their period) between the ages of 8 and 18. The average age is 12½ years in the United States. If a woman has not gotten her first period by the time she is 16, she may want to see a doctor to make sure that everything is okay.

Yes. A wet dream is also called a "nocturnal emission." Some boys have them and others do not; either way is perfectly normal. A wet dream is when a male ejaculates in his sleep. He may find wet semen on his pajamas or sheets when he wakes up. Some boys mistakenly think they have urinated or "wet the bed," but they have not.

Everyone's body changes during puberty. It may take a while for you to get used to all of these changes. Achy joints, sometimes called "growing pains," often happen during adolescence. This is just a sign that your body is growing; they will eventually stop. You may also be worried that you're developing faster or slower than your peers. But everyone develops at different rates.

During adolescence, many males and females develop sensitive tissue under their nipples. For males, this is common and temporary. A male's breasts may become slightly larger, but this usually disappears within one or two years. For females, this is usually a signal that their breasts are beginning to develop. A female's breasts may feel sensitive, sore or lumpy. Women's breasts are not perfectly smooth because they have milk ducts in them.

For women, it is important to do a breast self-exam every month to become familiar with one's own body and to check for new or abnormal lumps. A health care provider should be consulted if you have a family history of breast cancer or are concerned that you have new or abnormal lumps.

There is no set age by which people "should" begin having sexual intercourse. The average age of first sexual intercourse in the United States is 16. But it’s important that everyone makes that decision for themselves.

The National Commission on Adolescent Sexual Health has adopted a checklist to help young people assess their readiness for mature sexual relationships. Individuals who are ready for sexual intercourse should be:

• Committed to preventing unintended pregnancies and sexually transmitted infections
• Physically mature
• Knowledgeable about sexuality and sexual response
• Patient and understanding
• Able to handle responsibility for both positive and negative consequences of intercourse
• Honestly approving of the behavior

If you feel like you're not ready to start having sex, you're not ready. Don't ever let a partner—even one that you love—force you into a decision you're not ready to make.