Underarm hair normally starts to appear at the beginning of puberty , with growth usually completed by the end of the teenage years. Like much of the hair on the human body, leg, arm, chest, and back hair begin as vellus hair. It is differentiated from the head hair and less visible vellus hair , which are much finer and lighter in color. Just as individual people differ in scalp hair color, they can also differ in pubic hair color. The telogen phase for body hair lasts close to a year.