Is hair just on top of your head to look pretty? Well actually it has a greater purpose. Hair is on top of your head to help your body stay warm. It stops heat from leaving your body. It is a natural hat.
Babies do not have very much hair, but as they grow they soon have a full head of hair. Then at puberty they will grow thicker hair on their arms legs and armpits.
As boys become men they will also grow hair on their face. Some men prefer to shave off this hair and others don't. This is why some men have beards and mustaches. Then as men grow older sometimes they lose the hair on their head. This is caused by hormones in their body.