Hair loss or Alopecia is most common on the head but may affect any part of the body. It can develop either gradually or suddenly and may be caused by hereditary factors, aging, local skin conditions and systemic diseases or diseases that affect the whole body. Many drugs can also cause hair loss. This condition is generally referred to as baldness when it occurs in the head.There are about 5 general types of Alopecia namely: Androgenetic Alopecia, Toxic Alopecia, Alopecia Areata, Trichotillomania and Scarring Alopecia. The most common is Androgenetic Alopecia which eventually affects half of all males and 10% to 20% of women. A slightly elevated level of the male hormones dehydrotestosterone is seen as the most probable cause along with genetic factors. Hair loss can begin at any age even during the teenage years.Most men experience hair loss or male-pattern baldness beginning at the forehead or on the top of the head toward the back. Some may loose only a few hairs while others experience a receding hairline or a small bald spot at the back. Those whose hair loss began at a young age tend to lose all of the hair on top of the head while retaining hair on the sides and back of the scalp.Womenfs hair loss or female-pattern baldness usually begins on the top of the head and is inclined towards thinning of the hair rather than a complete loss of hair. The hairline stays intact most of the time. The discomfort and social factors surrounding hair loss in a woman makes it more difficult to bear than for a man.Toxic Alopecia is hair loss resulting from physical or psychological stress. Alopecia Areata is a common skin disorder in which round, irregular patches of hair are suddenly lost. Trichotillomania is the habitual pulling of normal hair while Scarring Alopecia is hair loss that occurs at scarred or damaged areas.