The chemical state of an organic compound that contains double or triple bonds — and therefore reacts more readily than its saturated counterparts — a concept used especially for fats and oils. The degree of unsaturation counts those multiple bonds and is measured analytically as the iodine value: the weight of iodine absorbed by the fat. Higher values mean more unsaturated, more oxidation-prone oils. Unsaturation dictates melting behaviour, nutritional character, and frying performance: highly unsaturated oils are heart-healthy but polymerize and degrade faster at frying temperatures, guiding oil choice for each application.