Wearing comfort is related to the thermo-physiological properties of a fabric. They depend upon the fabric's ability to conduct heat and the contact area of fabric with the body. The cellulosic content of the yarns determines the moisture content within the fiber. As a result, the wearer feels a cooling sensation. The yarn fineness and hairiness determines the wearing comfort because fine yarns provides a greater, smoother and softer surface to conduct heat away from the body. Furthermore, denim is very breathable because it has a high air permeability.