Inulin is a naturally occurring fructan polysaccharide composed primarily of β(2→1)-linked D-fructofuranose units with a terminal α-D-glucose residue. It functions as a storage carbohydrate in over 36,000 plant species including chicory, Jerusalem artichoke, and onions. With degrees of polymerization typically ranging from 2 to 60, inulin is a soluble dietary fiber that resists digestion in the small intestine and undergoes selective fermentation by colonic microbiota, producing short-chain fatty acids. Industrially, it serves as a prebiotic ingredient, low-calorie sweetener, fat mimetic, and texture enhancer in foods. Chemically stable under neutral conditions but hydrolyzes in acidic environments at elevated temperatures, inulin exhibits moderate water solubility that increases with heat and is insoluble in most organic solvents.