There exists a great number of dyes for a great number of applications. Dyes are usually categorised based on their properties. (e.g. reactive substance, dispersive, soluble, acid, alkaline, vat, direct, metal complex,…)
A dye is a substance that needs a certain affinity with the carrier on which it is being applied. Hence, the application of certain dyes is limited:
Coton: Reactive, vat and direct dyes
Leather: Acid and direct dyes
Or Solvent/corrosive dyes: candles, gasoline, PVC, Polyester
Acidic dyes: wool, fleece, nylon