An unsaturated fat is a fat or fatty acid in which there is one or more double bond in the fatty acid chain.
A fat molecule is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond.
Where double bonds are formed, hydrogen atoms are eliminated.
Thus, a saturated fat is "saturated" with hydrogen atoms.
The greater the degree of unsaturation in a fatty acid (ie, the more double bonds in the fatty acid), the more vulnerable it is to lipid peroxidation (rancidity).
Antioxidants can protect unsaturated fat from lipid peroxidation.
Foods containing unsaturated fats include avocado, nuts, and soybean, canola, and olive oils.
Meat products contain both saturated and unsaturated fats.
Usaturated fats are liquid at room temperature.