Puberty

During puberty, your body will grow faster than any other time in your life, except for when you were an infant. Back then, your body was growing rapidly and you were learning new things — you'll be doing these things and much more during puberty. Except this time, you won't have diapers or a rattle and you'll have to dress yourself!

It's good to know about the changes that come along with puberty before they happen, and it's really important to remember that everybody goes through it. No matter where you live, whether you're a guy or a girl, or whether you like hip-hop or country music, you will experience the changes that happen during puberty. No two people are exactly alike. But one thing all adults have in common is they made it through puberty.

When your body reaches a certain age, your brain releases a special hormone that starts the changes of puberty. It's called gonadotropin-releasing hormone, or GnRH for short. When GnRH reaches the pituitary gland (a pea-shaped gland that sits just under the brain), this gland releases into the bloodstream two more puberty hormones: luteinizing hormone (LH for short) and follicle-stimulating hormone (FSH for short). Guys and girls have both of these hormones in their bodies. And depending on whether you're a guy or a girl, these hormones go to work on different parts of the body.

For guys, these hormones travel through the blood and give the testes the signal to begin the production of testosterone and sperm. Testosterone is the hormone that causes most of the changes in a guy's body during puberty. Sperm cells must be produced for men to reproduce.

In girls, FSH and LH target the ovaries, which contain eggs that have been there since birth. The hormones stimulate the ovaries to begin producing another hormone called estrogen. Estrogen, along with FSH and LH, causes a girl's body to mature and prepares her for pregnancy.

So that's what's really happening during puberty — it's all these new chemicals moving around inside your body, turning you from a teen into an adult with adult levels of hormones.

Puberty usually starts some time between age 7 and 13 in girls and 9 and 15 in guys. Some people start puberty a bit earlier or later, though. Each person is a little different, so everyone starts and goes through puberty on his or her body's own schedule. This is one of the reasons why some of your friends might still look like kids, whereas others look more like adults.