Hair is a strand of string protein that grows out of hair follicles or tiny sacs in your skin. Hair is made up of keratin, the same material your fingernails are made out of. Hair grows through a process of cells dividing and getting pushed out of the follicle. This causes a strand of cells and proteins to rise out and that is what we see as hair! Hair is used to keep us warm, keep dirt from touching our skin, and cushions your skull. Hair is an identifying feature on many mammals and is important for survival.