At any Stage of our life, only 10% of hair is in resting phase. They Fall off in 2-3 months and the new hair grows in a total time of 2-6 years. About 90% of the hair grows on our scalp at a time and They grow at a rate of 1 cm. per month.Normally hair lasts for two to four years in men and four to six years in Women.

Hair Internal Structure : Deep Inside The hair follicle, the hair forms inside a hair bulb and protrube and grow outside.Any Method of hair improvements like shampooing, conditioning, cutting, sun exposure does not effect the rate of grwth of the hair.
There Are 3 phases of hair growth -

1. Anagen which takes a time of about 1000 days or 3 years.

2. Catagen lasting for 10 days.

3. Tologen for nearly 3 months.

Anagen includes the start of growth of hair and Tologen is the end i.e. trhe shedding phase of hair. The Hair bulb goes on coming outside from the start to the shedding phase. Hair groth is effected by the seasonal changes, i.e. hair grows more quicker in winter than in summer as a result of the seasonal change. In the Catagen phase, Hair growth is stopped for a small time and no pigment is produced at this time.
The time of Anagen Phase is usually fixed and and is determined genetically and is also responsible for the length of the hair. The no. of Hair Follicles in a human head counts approximately 100,000. Each Follicle produces hair for about 20 times in the lifetime. In a new born baby, the hair follicles grow hair in a Unison, i.e. all at a same time but as time passes, the follicles produce hairs at different times.
If a hair is Plucked from the head, the follicle is not ruptured but it starts to produce a new hair. As age increases, the shedding of follicles is evidently seen in most of the people in the top of the head and also in the forehead. The Hair does not grow in a definite straight manner but makes the follicle to stand in some constant angle. Depending on this angle, the Hair are always set to lie. The Stream is usually in a twisted manner but it is then influenced by the way of combing of hair by people.

Finally, Hair grows at a slow rate, so utmost care is needed to prevent them from shedding.