Twill fabric is a type of woven fabric that has a distinct pattern of diagonal parallel ribs. It is usually made from cotton, wool, or synthetic fibers. Serge is a type of twill fabric with a smooth, even surface and a diagonal rib on the face of the fabric. CHINO is a type of twill fabric that is usually made from cotton and has a soft, slightly brushed surface. REP is a type of twill fabric that is made from silk and has a glossy finish.