What is normal hair loss and excessive hair loss?

Shedding
During the resting period of the cycle, the hair follicle is reaching the point of detachment and the bulb of the hair shaft moves closer to the surface of the scalp. As time passes during this period, shampooing and other movement on the scalp will cause the hair to disengage from the scalp. This is part of the normal shedding process. We shed an average of 50-100 hairs per day. Under normal conditions new hairs grow to replace each hair that has been shed, keeping the average number of growing hairs about the same at all times. Hair loss may involve many unknown factors, however, healthy hair is part of the over all good health of any person and is directly related to healthy conscientious nutrition. A well balanced diet may not interfere with a genetic predisposition – however it will support the health and appearance of the hair that is retained on your head.
50 Hair Example:For the first example, we have a person with about 100,000 active hair follicles on their scalp, with a 60 month average growth period, and a 3 month average rest period. On average they will shed about 1/63 (60 months +3 months ) of their hairs in any given month, or about 1,500 hairs every 30 days. This works out to about 50 hairs per day, and would be normal hair loss.

New Hairs Grow:
Under normal conditions, approximately the same number of new hairs will just start growing to replace the hairs that have been shed, so the average number of growing hairs remains about the same all the time.
Hair loss may affect anyone at any age, Androgentic hair loss being the most common form of hair loss. Hair loss may also be the result of an auto immune reaction, in which a person's immune system attacks the hair follicles, as in Alopecia Areata, Alopecia Totalis and Alopecia Universalis. Hair loss may also be self inflicted as in Trichotillomania. Hair and its appearance contributes greatly to our self-esteem – hair loss may be interpreted as some form of illness or a diminished vitality. Studies have indicated that hair loss has had a detrimental effect in the efforts of men and women persuing high profile careers as well as children and adolescents persuing their education