Dyeing is the process of changing the colour of a yarn or cloth by treatment with a dye.
For the majority of the thousands of years in which dyeing has been used by man to decorate clothing, or fabrics for other uses, the primary source of dye has been nature, with the dyestuff being extracted from animals or plants. In the last two centuries, man has produced artificial dyes to achieve specific colours, and to render the dyes 'fast', so that they do not run when the material is washed.
Dyes are applied to material by direct application, or by immersing the yarn or cloth in the liquid dye or a solution of the dye.
In order to remove natural or unwanted colour from material, the opposite process of bleaching is carried out.