The study of hair is called Trichology.
Hair covers all parts of the body, except for the lips, palms and soles.
It even covers parts of the reproductive organs. You are probably not aware of the amount of hair you have unless it is growing in undesirable areas. Hair has a very practical purpose. In your nose and ear, it keeps foreign bodies from invading you. Under the arms and in the pubic areas, it protects your body from friction.