1. usually referred by common name
2. Two numbers separated by colon, 1st designates the # of carbon, 2nd is the # of DB
Ex. 18:2 = 18 carbons, with 2 DBs
3. location of DBs use Δ. delta notation always has carboxyl carbon as C₁
ex. 18:3(Δ⁹'¹²'¹⁵) = 18 carbons, 3 DBs, located btw 9-10, 12-13 & 15-16 carbons
4. MUFA;s are usually Δ⁹ acids
5. polyunsaturated are usually at the Δ¹² & Δ¹⁵