The adult human body has an average of about five million hair strands, of which 100,000 to 150,000 are on the scalp.
Hair is composed of keratin, the same protein that makes up nails and the outer layer of our skin.
The part seen rising out of the skin is called hair shaft or strand. Each strand consists of three layers. The middle layer or cortex, is the thickest. It provides strength, determines your hair color and whether your hair is straight or curly. Below your skin is the hair root, which is enclosed by a sack-like structure called the hair follicle.