I am 15. Why haven't I gone through puberty yet?
Each person is different and the time at which the changes occur are different. The normal range for the start of puberty is between nine and sixteen. The average (when most boys start) is eleven and a half. It is tough when you haven't started, but everyone you know has not only started but appear much more physically mature than you. You could ask a doctor to check that everything is normal, but most likely he won't be very concerned unless there are no signs of starting by sixteen.
Often boys miss the early signs of puberty. Everyone thinks about growing tall, developing body hair, and putting on muscles, but each of these are changes that don't begin until two or more years after puberty is reached.
The earliest sign of puberty is a swelling of the scrotum as your testicles begin to grow. At first it doesn't appear to be much, unless you compare your scrotum to a child who hasn't developed at all, then you notice that there is a difference.
The typical second sign is hair showing up at the base of your penis. At first it will look like your are getting goose bumps. This is because the shafts of each hair is a bit big for the size of the opening through the skin. As it pushes out, it pushes the skin up a bit, making it look like fine bumps. The early hair is very fine and doesn't have much color, so it is easy to miss. Within a few months it will both thicken and take on a darker color. It is usually at this point that boys realize something is going on. But the reality is that something has been going on for over a year, it is just that most of the changes have been internal instead of external. To estimate what stage of development you are in, see the Tanner Stage Calculator for Boys.