Many studies have shown that unsaturated fats, particularly monounsaturated fats, are best in the human diet.

Saturated and some trans fats are typically solid at room temperature (such as butter or lard), while unsaturated fats are typically liquids (such as olive oil or flaxseed oil).

Fatty acids are considered the monomer in that case, and may be saturated (no double bonds in the carbon chain) or unsaturated (one or more double bonds in the carbon chain).

Trans fats are a type of unsaturated fat with trans isomer bonds these are rare in nature and in foods from natural sources they are typically created in an industrial process called (partial) hydrogenation.

Saturated fats have all of the carbon atoms in their fatty acid chains bonded to hydrogen atoms, whereas unsaturated fats have some of these carbon atoms double bonded, so their molecules have relatively fewer hydrogen atoms than a saturated fatty acid of the same length.