A fatty acid is a carboxylic acid with a long unbranched aliphatic tail (chain), which is either saturated or unsaturated. With the CAS registry number 67254-79-9, Fatty acids is also named as Mixed fatty acids. The other registry numbers are 12624-10-1, 60572-00-1 and 8039-43-8. And the classification code is TSCA UVCB. Saturated fatty acids are long-chain carboxylic acids that usually have between 12 and 24 carbon atoms and have no double bonds. Unsaturated fatty acids resemble saturated fatty acids, except that the chain has one or more double-bonds between carbon atoms.

These chemicals are produced by the hydrolysis of the ester linkages in a fat or biological oil (both of which are triglycerides), with the removal of glycerol. Fatty acids are mainly used to produce daily cosmetics, detergents, industrial fatty acid salt, coatings, paints, rubber, soap, etc.