The typical average loss of hair amounts to about 100 strands a day. Male pattern baldness, also known as alopecia, is characterized by hair that is receding from the lateral sides of the forehead, known as a receding hairline; an additional bald patch may also develop on top of the head. The severity and nature of baldness can vary greatly; it includes male and female pattern baldness which is alopecia areata, which involves the loss of some of the hair from the head, and alopecia totalis, which involves the loss of all head hair, to the most extreme form, alopecia universalis, which involves the loss of all the hair from the head and the body.

