The major component of an oil or fat containing a long hydrocarbon chain. Edible oils and fats are triglycerides, i.e. combinations of fatty acids with glycerine, in which three fatty acid molecules are joined with each glycerine molecule. Most fats contain many different fatty acids.

An oil or fat normally consists of a number of fractions, each of which has different physical characteristics. Fractionation is the separation of selected fractions with the object of obtaining a product with different physical characteristics from the original fat.

The combination of fatty acids with glycerol to form glycerides is sometimes reversed resulting in the presence of uncombined or free fatty acids. These are usually found in crude oils and may be removed by neutralisation.