Male Pattern Baldness is the most common type of hair loss in men. It usually follows a typical pattern of receding hairline and hair thinning on the crown. The typical pattern of male baldness begins at the hairline. The hairline gradually recedes to form "M", "O", "A", or "O+M" shape. The existing hair may become finer and shorter. The hair at the crown also begins to thin. Eventually the top of the hairline meets the thinned crown, leaving a horse shoe pattern of the around the sides of the head. Most men are genetically predisposed to male pattern baldness.
It is the effect of hormones on the hair follicle that produces male pattern baldness. This loss is caused by dihydrotestosterone (DHT).