Hair grows in hair follicles. The hair follicle is like a factory for manufacturing hair, and a healthy hair follicle is what makes healthy hair. Hair grows and sheds continuously, showing a cycle that can be divided into three phases: anagen, regression and resting. The anagen phase is the period of hair growth when the hair follicles are active and the hair grows at a rate of about 0.3 mm/day (i.e. about 0.8-1 cm/month); the degenerative phase is when the hair follicles begin to degenerate and the hair stops growing; the resting phase is when the hair follicles degenerate and shrink and the hair falls out. Tips:Adults shed 20-100 hairs per day is a normal metabolic phenomenon, but too much hair loss or just shedding without growth, then it is not normal, you should seek medical attention.