Hair Growth Cycle
Normally, number of hair on human head is ranged between 100,000 – 150,000 and hair growth rate is about 1.0 – 1.5 cms. per month. The three of hair growth are :

ANAGEN
Anagen – the growing phase
This phase is known as the growth phase. It begins in the dermal papilla and can last from 3 – 8 years. About 85-90% of the hair are on one’s head during this phase.
CATAGEN
Catagen – the intermediate phase
This phase is also known as the transitional phase, allowing the follicle to, in a sense, renew itself. During this time, it lasts about 2 – 3 weeks.
TELOGEN
Telogen – the shedding, resting phase
This phase is the resting phase. About 14% of the hair on one’s head are in this phase of growth and ready to be shed. The anagen phase begins again once the telogen phase is completed.
Information from Hair Care & Section Research & Development Dept. International Laboratories Corp., Ltd.