Everybody's different, but for most guys, changes start happening between 10 and 14.

Usually, the first sign of puberty is your testicles get bigger. Next comes pubic hair, and then your penis starts getting bigger. After that, guys' voices begin to change, your muscles get bigger, and you start to grow underarm hair. About the same time, there's a growth spurt. Facial hair usually comes last.

Acne is a normal part of puberty. Your body makes hormones that make your face oily, which can cause pimples. Oil glands in the face are usually more active in guys than girls, so your acne can be worse.

You can't stop acne from happening, but you can cut down on breakouts by washing your face twice a day. Don't scrub too hard, though. Tougher cases may need over-the-counter or prescription medication.

It’s caused by hormones and usually goes away on its own. Your nipples may also be sore or temporarily swollen.

Your hands and feet grow first. Then your arms and legs, and then the rest of your body.

Both guys and girls need a lot of sleep during puberty: about 9 hours every night. Even though you need more sleep, teens often get less than they did as kids. Make sleep a priority.

If you're in middle school or junior high, girl classmates may suddenly get taller than you. That's normal. Once your growth spurt starts, it will take 2-3 years. Remember, everyone is different, so don't get too hung up on the exact timeline. It will happen!

Most guys in puberty start making sperm, which means you could get someone pregnant. Exactly when during puberty that happens can't be pinpointed, but sperm count goes up as puberty progresses.

Delayed puberty usually doesn't need medical treatment. A doctor can check that there's no medical reason behind it. It's often because of a family history of late bloomers. 

During puberty, you become better at abstract thinking, planning, and setting goals for the future. You also start exploring your personality and the kind of person you want to be when you get older.

Testosterone is the main hormone responsible for physical changes in guys. During puberty, you make 20 times more testosterone than before.

Teen guys eat a lot. Before puberty, boys eat about 1,300 calories for lunch. Guys age 14 to 17 eat 2,000 calories. Teen guys eat more because their bodies need more calories and nutrients to support their rapid growth and development.

Testosterone levels peak late in puberty, and guys tend to do more reckless, even dangerous or violent things. You'll need to hit "pause" and use all the good judgment you can find.

Guys who go through puberty faster than normal tend to be more aggressive or get in more trouble. Experts think that may be because they don’t have as much time to adjust to the changes in their mind and body. However, you're still responsible for your actions and can make good choices. A lot of guys do the right thing, even in the middle of puberty.