<unk>  is defined as the loss of hair regardless of the cause. It can occur anywhere on the body. The hair cycle consists of three phases: the anagen phase, which is the growth phase, the catagen phase, which is the resting phase, and the telogen phase, which is the shedding phase. This is the phase where hair falls out. Ninety percent of hair is in the anagen phase and the remaining ten percent are in the catagen phase and telogen phases. In the telogen phase, hair is going to recycle, and it starts growing again in the anagen phase.
Alopecia
Cicatricial alopecia
Scalp rash
Sunburn
Dermatitis
Onycholysis
Traction alopecia
Xerosis