Hair phases refer to the different stages of hair growth, which include three main cycles: 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 hair follicle shrinks. Finally, the telogen phase is the resting stage, lasting several months, during which old hair falls out and new hair begins to grow. Each hair on the scalp is in a different phase at any given time, which is why people do not lose all their hair simultaneously. Typically, about 85-90% of hair is in the anagen phase, while 10-15% is in the telogen phase. Factors such as genetics, health, and environmental influences can affect the duration and quality of these phases, impacting overall hair growth and shedding patterns.