1. Anagen: The active growth phase. During this phase, hair follicles produce new hair cells, causing the hair shaft to grow longer. This phase can last anywhere from 2 to 7 years, depending on the individual and the location of the hair on the body.
2. Catagen: The transitional phase. During this phase, hair growth slows down and the hair follicle shrinks. The hair shaft detaches from the follicle, but remains in place. This phase lasts for about 2 to 3 weeks.
3. Telogen: The resting phase. During this phase, the hair follicle remains dormant, and the hair shaft sheds. This phase lasts for about 3 to 4 months, after which the hair follicle enters the anagen phase again and a new hair begins to grow.