Hair is a slender, thin, thread-like fiber composed mostly of protein, also referred to as keratin. Hair can be found all over the body mainly on the scalp, armpits and other places. There are hundreds of thousands of hair strands growing all over the body. Trichology, The study of hair concerns itself with the papilla, bulb,follicle,root, and the hair shaft. The root of the hair is located beneath the surface if the skin. 

Then there is the papilla, located at the bottom of the hair shaft and inside the bulb. The bulb is rounded and tear shaped. The bottom end or hair strand is where hair receives most of its nourishment. Size and shape of hair is determined by size and shape of the follicle. 

If the opening of the follicle is round.p, hair will be straight, if the follicle is flat, hair will be curly or kinky. If follicle is oval shaped hair will be wavy. 

The first layer of the hair is called the cuticle or the protective layer. When magnified a thousand times, the cuticle looks like the scales on the back of a fish. When chemicals are applied to the hair shaft, they raise the cuticles, allowing products access into the second layer of the hair, the cortex. 

The healthier the cuticle layer of the hair , the healthier hair will be. Hair grows about one -half inch per month. We shed 100-150 strands of hair per day. Once hair grows out of the scalp it is dead. The outer layer of hair , the cuticle must be protected, by using the right conditioners. The cortex or second layer is where everything you put into your hair enters through the cuticles. The includes: shampoos, conditioners, hair color and even water. 

The cortex is where the bonds are located and where peroxide based hair colors , relaxers, curl perms and other chemicals will cause permanent damage to the hair. The medulla or third layer makes hair softer and more porous. The term porous means hairs ability to absorb moisture. Ethnic hair does not have a medulla.