Denim
Denim is a cross twill weave fabric with (blue) coloured warp yarn and white weft yarn. This makes the front side of the fabric darker than the back side. A cross twill weave has a typical diagonal line in it. The weft yarn of the weave lies over one or more warp yarn(s) and then lies underneath two or more warp yarns. Every next yarn starts one weft higher. The front and the back of the fabric have a different look.
Trousers, skirts, jackets, bags, cushion covers, upholstery