Dye is a chemical solution used to produce long-lasting colors in materials. The textile industry uses dyes to color fibers, yarns, and fabrics. Manufacturers also dye food, fur, ink, leather, paper, plastics, and wood. This article primarily discusses textile dyeing.

Dyes are made from substances called dyestuffs. Until the 1850's, all dyestuffs came from natural sources, such as parts of plants or animals. Today, industry uses synthetic dyestuffs almost entirely. The dyes they produce hold their color better and cost less than natural dyes.