FFAs can be categorized according to the length of the carbon chain (box), the presence of double bonds and the position of the first double bond. Depending on the presence of one or more double bonds, FFAs are classified into saturated (SFA), monounsaturated (MUFA) and polyunsaturated FFAs (PUFA). Depending on the position of the first double bond counting from the methyl end of the chain, FFAs are classified into omega-3, omega-6 etc. This figure does not provide an exhaustive list of common FFA names and symbols, but illustrates the FFAs mentioned in the text. Additional systems of FFA nomenclature exist.