Denim is a sturdy cotton warp-faced textile in which the weft passes under two or more warp threads. This twill weaving produces a diagonal ribbing that distinguishes it from cotton duck. While a denim predecessor known as dungaree has been produced in India for hundreds of years, denim itself was first produced in the French city of Nîmes under the name sergé de Nîmes.
Denim is available in a range of colors, but the most common denim is indigo denim in which the warp thread is dyed while the weft thread is left white. As a result of the warp-faced twill weaving, one side of the textile is dominated by the blue warp threads and the other side is dominated by the white weft threads. Jeans fabricated from this cloth are thus predominantly white on the inside. https://nl.wikipedia.org/wiki/Denim