<P> Hair follows a specific growth cycle with three distinct and concurrent phases: anagen, catagen, and telogen phases . Each phase has specific characteristics that determine the length of the hair . All three phases occur simultaneously; one strand of hair may be in the anagen phase, while another is in the telogen phase . </P> <P> The body has different types of hair, including vellus hair and androgenic hair, each with its own type of cellular construction . The different construction gives the hair unique characteristics, serving specific purposes, mainly warmth and protection . Most humans develop the longest thickest hair on their scalps and (mostly observed in males) faces . This hair will usually grow to several feet before terminating, but many humans develop much longer hair . </P> <P> 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 . </P> <P> The anagen phase is known as the growth phase . It begins in the papilla and can last from two to six years . The span at which the hair remains in this stage of growth is determined by genetics . The longer the hair stays in the anagen phase, the longer it will grow . During this phase, the cells in the papilla divide to produce new hair fibers, and the follicle buries itself into the dermal layer of the skin to nourish the strand . About 85% of the hairs on one's head are in the anagen phase at any given time </P>

How long dose it take for hair to grow