A chemical extracted from the leaves of a plant, it is widely used as dye to color denims as it imparts a brilliant blue hue to fabric. Naturally produced from leaves of a plant. Its unique because it imparts surface color while only partially penetrating fibers. As per Roman term, Indigo means product of India which was known for its production since the ancient times. These days synthetic indigo dyes are produced which are very hazardous to environment.