What is the difference between a saturated and unsaturated fatty acid?

Saturated fatty acids have no double bonds between the carbon atoms in their carbon chain (the carbon chain is ‘saturated’ with hydrogen). In contrast, unsaturated fatty acids have at least one double bond between the carbon atoms in their carbon chain (this causes the chain to kink).The difference in carbon chain causes the properties of the fats to vary. In an fat with an unsaturated fatty acid tail, the ‘kink’ in the carbon chain means the molecules are not able to pack together as tightly as they do in a saturated fat. This means that in general, unsaturated fats have lower melting and boiling points than saturated fats.