Puberty is the process of growing from a boy into a young man. Here's what to expect.
If puberty hasn't started yet, don't worry. Most boys begin when they're around 13 or 14 years old, but some start earlier and some later.
We all grow and change at different rates, and there's nothing you can do to make it happen sooner or later. Your body will change when it's ready.
It's normal to feel confused or worried sometimes. It can help to talk to someone you trust, such as your dad, mum, brother or a trusted teacher.
There are plenty of signs that puberty has started. Every boy is different, but here are some of the most common changes to look out for:
Your body grows, and it may become more muscular.
Bigger penis and balls
Your testicles and penis grow, and they may feel itchy or uncomfortable.
Your body produces more hormones, so you might get erections when you least expect them.
Spots and sweat
Hormones can make you sweaty and spotty, but as long as you have good personal hygiene, you can still look and feel healthy.
You start producing sperm, and you may have wet dreams in which you ejaculate (release fluid containing sperm out of your penis) while you're asleep. This is normal.
Areas of your body become more hairy, including your armpits, legs, arms, face, chest and around your penis.
As your voice begins to break, you might sound croaky for a while, or you might have a high voice one minute and a low voice the next. It will settle down eventually.
You may have mood swings and feel emotional, but your feelings will settle down in time.
For more information, read the boys' bodies Q&A, which includes answers to questions about penis size and sperm.