FASHISM magazine denim issue: Into The Blue is talking about what denim is, and introduce denim's brand and some facts about denim, Denim is a durable cotton twill textile, typically used to make jeans, overalls, and other clothing. To create denim fabric, the weft (horizontal threads) passes under two or more warps (vertical threads) threads. This process makes diagonal ribbing of denim that distinguishes it from cotton duck, another twill fabric.