Human hair growth
The three stages of hair growth are the anagen, catagen, and telogen phases. Each strand of hair on the human body is at its own stage of development. Once the cycle is complete, it restarts and a new strand of hair begins to form. The rate or speed of hair growth is about 1.25 centimetres or 0.5 inches per month, or about 15 centimetres or 6 inches per year.
Vellus hair
Vellus hair grows individually or in small patches of varying, and sometimes irregular, length (2–4 cm). These irregularities are governed by genetics, and often persist throughout a lifetime. This kind of hair growth is usually not harmful.