Fats are made of fatty acids and glycerol which combine with a dehydration reaction. Fats are differentiated by the fatty acid that is present in them. Fatty acids are formed of the elements carbon, hydrogen and oxygen and are linked together to form a carbon chain. At the end of each carbon chain is a carboxyl group (-COOH).
Fats are divided into various categories based on the number of bonds that the carbon atoms in the fatty acids have, saturated fatty acids have all the hydrogen atoms that the carbon atoms can hold and no double bonds between the carbon atoms. Fatty acids which have only one double bond are called monounsaturated and those which have more than one double bond are called polyunsaturated fatty acids.