Polyunsaturated have linked with the production of free radicals which produce carcinogens. Monounsaturated are the safest. Linolenic acid has 18 C and 3 unsaturated positions. Leads to an off taste in fats. Saturated oils tend solid while unsaturated tend be oils.
Cholesterol is an oil that consist of complex series of rings.
These are found in the diet and formed by the liver and overabundance is thought to be detrimental in the body. The omega fatty acids are unsaturated comparatively high carbon chain lengths C20 and C22. Soaps are now mostly made from vegetable oils and not lard. Linseed oil and tung oil polymerize to form long molecular strings and are applied to wood surfaces as protective coating if color is added they may be decorative. The oils are boiled with magnesium cobalt or formerly lead to make oxygen easily able to attach to the double bonds so that they form hard films.