Boys usually start going through puberty a bit later than girls, usually between the ages of 10 and 18, with the average age around 12.
During this time a boy will experience a lot of physical and emotional changes caused by the hormone testosterone.
What happens physically?
Growing
Lots of changes occur over the course of puberty, and happen at different times and rates for everybody. You will notice that you get taller and heavier, your chest and shoulders get broader and that your penis (dick) and testicles (balls) get bigger. At around the same time you will find you are getting hairier, and will notice hair beginning to grow on your arms and legs, around your genitals, in your armpits and also on your chest. Hair will also start appearing on your face, around the chin and top lip, which is when many boys start thinking about shaving.
Spots
Most teenagers experience getting spots on their face, and unfortunately some people get more than others. These are caused by hormones and have nothing to do with eating chips and chocolate! Some people find using a special face wash helps, but some people get lots of painful spots called acne and may need medication from their doctor.
Sweat
You will also find that you sweat changes, meaning that you sweat more than you did before and that it is smellier, causing B.O. (body odour). There are lots of deodorants available which can easily help with the smell, as well as remembering to have regular baths and showers.
Voice
As boys develop their voices get deeper, and this is known as your voice breaking. Just like everything else it does not happen overnight. You might find that your voice is a bit unpredictable for a while and that when you speak it crackles, wobbles or changes pitch suddenly. This might feel a little embarrassing but is completely normal.
Erections
All of a sudden it might feel that your penis has a mind of its own, and you will find that you have erections (hard-ons) more often. Some happen when you expect them, because you are thinking about sex and the people you fancy, but some erections appear for no reason at all! This can make you feel embarrassed or awkward, but usually no-one notices but you. You might also get erections, and ejaculate (cum), in your sleep, and wake up with damp clothes or sheets. This is called a wet dream and happens to most boys.
What happens mentally?
Sexual feelings
All the extra hormones in your body affect your mind as well, and you may find that you are becoming more interested in sex, start fancying people, and thinking about having a boyfriend or girlfriend. You may also be interested in exploring your own body and what feels good through masturbating (wanking), which is completely normal. All this is part of your developing sexuality.
Emotions
Unfortunately not all your new feelings will be exciting sexual ones. You might also find you become moodier, and have more arguments with your family and friends, or that you feel more confused and worried about things than you used to because lots of things are changing. It is really normal to feel like this and if you are worried it might help to talk things through with someone you trust.