The average human adult body has an astounding 5 million hairs of which 100,000 to 150,000 are on the scalp. True blondes have more hair on the scalp - 140,000 hairs than brunettes (105,000 hairs) or redheads (90,000 hairs). Hair is made up of a protein called Keratin. Keratin is also a constituent of our nails.

* Hair around the world

Hair color and texture differ around the world. Asians have jet-black hair whereas Scandinavians have varying shades of browns and reds to the pale blonde. There are generally three racial groups with three types of hair.

1. Oriental - People from Japan and China have straight and black hair.

2. Caucasoid - This group is varied and a mixture of several racial groups. The hair colors range from black to blonde. The hair can be wavy or straight.

3. African - African people have black hair that is tightly curled. It is woolly and dry. Heat or chemicals can easily damage this type of hair.

* Hair structure

Some part of hair is hidden under the skin, while the rest is seen outside the body. The part of hair hidden under the skin is the hair follicle. There are tiny blood vessels at the base of the follicle that provides nutrition to the hair.

Sebaceous glands secrete sebum that keeps the hair shiny and waterproof to some extent. At the root of the hair follicle is the papilla, which is where the hair grows. Hair follicles are formed when the baby is still in the womb.

After birth, there is no new growth of hair follicles. The hair strand itself consists of three layers. The outermost layer called the cuticle is thin. The middle layer called the cortex is thick. The cortex provides the hair its strength, color and determines whether hair will be wavy or straight.

* Hair Growth

The hair grows at the rate of 12 millimeters every month. Hair grows the best between 10 AM to 11 AM and again between 4 PM to 6 PM. It is also generally known that hair grows faster in summer than winter. Hair grows the best between the ages of 15 to 30 and slows down from the age of 40 onwards. Both genders start natural hair loss in 50s.

Hair rejuvenation takes place on a daily basis. Hair grows and sheds. You normally shed 50 to 100 hairs per day. Any loss above that or visible patches of baldness are a cause for worry and can be classified as hair loss.