Denim is a twill-weave cotton fabric with a colored warp thread and white weft thread. The warp thread is usually indigo but can be found in other colors as well. Because of the twill weave and multicolored threads, denim generally appears indigo from one side and white from the other. One of the most popular properties of denim is the way it fades, caused by the white core of the warp threads appearing after heavy wear. Denim is often confused with chambray, but it’s not the same - denim is woven with a twill weave instead of a plain weave.