Human hair is a filamentous biomaterial that grows from follicles in the skin. It is primarily composed of a protein called keratin, which provides strength and resilience. Hair serves various functions, including protection from environmental elements, regulation of body temperature, and sensory perception. The structure of human hair consists of three main layers: the cuticle, the cortex, and the medulla. The cuticle is the outermost layer, providing a protective barrier. The cortex contains the bulk of the hair's mass and is responsible for its color and texture. The medulla, found in some hair types, is the innermost layer and may play a role in insulation.