Human hair is made out of a protein called keratin. Each hair grows from a hair follicle which anchors the hair to the skin. Hair is one of the main features which define us as mammals, as the hair follicle is considered a mammalian skin organ.
Hair varies greatly depending on the person—growing in different shapes, colors, and places on different individuals. The average growth rate is one-half inch per month. Hair color is decided in the hair follicle, where the melanin pigments are produced. As we get older, melanin production decreases or may stop completely, resulting in pigment-less hair, or gray hair.
Hair is very important, providing many functions including warmth, protection, and touch sense. The eyebrows and eyelashes protect the eyes from foreign bodies as well as from sweat. They help to keep the eyes clean from infection by trapping dirt before it can get to them. When the eyelashes sense dirt, the eye reflexively closes.
We are greatly influenced and defined by our hair. Straight, wavy, curly; red, blonde, brown. No two people have the same hair.