Skin and hair
Even at its thickest point, your skin is only a few millimeters thick. Even so, at almost one-seventh of the body's weight, the skin is the body's biggest organ. This surprisingly great weight indicates just how important the skin is for the body’s metabolism and internal balance. Hair and skin provide a stable and flexible covering for the body, offering protection against injury and dehydration, cold and heat, ultraviolet light and germs. And the skin is a sensor for touch and pain.