Being classified as polyunsaturated fatty acids (PUFA), Omega-3’s have a
double bond in the third carbon position from the methyl terminal
(hence the use of "3" in their description).
The three known Omega-3’s are the long chain (with 14 or more carbons) fatty acids: ALA (alpha linolenic acid), EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).