It is a skin disease and it occurs when hair follicles become clogged with dead skin cells & ail from the skin.
Men loss the hair on top of their head (framing a loss-shoe shaped ring) which is called as male-patterned boldness & is caused by genes & male hormone testosterone. In females, the pattern of hair loss is diffused i.e. the hair thins throughout the top of the scalp.
Causes :-
1]. Genetic.
2]. Hormonal.
3]. Infections.
4]. Smoking.
5]. Psychological.
6]. Diet.