The hair cycle consists of three main phases: anagen, catagen, and telogen. The anagen phase is the active growth stage, lasting several years, during which hair follicles produce new hair. The catagen phase is a transitional stage lasting a few weeks, where hair growth slows and the follicle shrinks. Finally, the telogen phase is a resting period lasting several months, after which the hair falls out, making way for new growth. Each hair on the scalp operates independently, meaning different hairs can be in different phases at the same time. Factors such as genetics, health, and hormones can influence the duration of each phase. Understanding the hair cycle can help in managing hair health and addressing issues like hair loss.