Hair is primarily made up of protein which occurs as the result of linking together of amino acids. The cortex of the hair is made up of a series of chains that form the shape of a coil. The amino acid chains coil around each other and become protofibrils. The protofibrils than twist around each other to become microfibrils. Microfibrils follow the same process and become macrofibrils that also spiral together. This process when complete, forms the cortex of the hair. The cortex is then covered with the cuticle scales which also contain protein. This twisting gives hair the ability to stretch like a spring without breaking.