Fatty Acids
These are the main components of all oils; and the types and concentrations found in each is what gives it the properties it has.
Fatty acids are long chains of carbon with an OH and O on one of the ends (COOH). Stearic Acid, for instance, has 18 carbons in it's chain and hence is labelled C18. It's carbons are all joined with a single bond; such fatty acids being called saturated.
Some fatty acids contain carbon double bonds in the chain, making them unsaturated with hydrogen. These are labelled with a number that states the number of double bonds and the number in the chain where the double bond exists. For instance, Oleic acid is C18:1 n-9 which means that it has 18 carbons in it's chain, with one double bond (:1) which is on the 9th (n-9) carbon from the end the in the chain.