Dyeing is the process of adding color to textile products like fibers, yarns, and fabrics. Dyeing is normally done in a special solution containing dyes and particular chemical material. After dyeing, dye molecules have the uncut chemical bond with fiber molecules. The temperature and time controlling are two key factors in dyeing. There are mainly two classes of dye, natural and man-made.

"Greige" (but, pronounced as "gray", the color, is). Greige fabric is the term used for fabrics before they are printed or piece-dyed. The quality of greige goods can vary and thus, can affect the outcome of the dye or print job and overall "hand" of the fabric purchased at the retail or garment manufacturing level. Greige fabric is the common name for fabrics that are taken direct from the weaving or knitting machine. The gray fabric, woven cotton fabric in its loom-state, not only contains impurities, including warp size but requires further treatment in order to develop its full textile potential.

Denim is sturdy cotton warp-faced fabric in which the weft passes under two or more warp threads. This twill weaving produces a diagonal ribbing that distinguishes it from cotton duck. 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. This causes blue jeans to be white on the inside. The indigo dyeing process, in which the core of the warp threads remains white, creates denim's signature fading characteristics.