Inulin is a naturally occurring fructan polysaccharide composed primarily of β-(2→1)-linked D-fructofuranosyl units with a terminal α-D-glucopyranosyl residue. It functions as a storage carbohydrate in over 36,000 plant species including chicory, Jerusalem artichoke, and onions. As a soluble dietary fiber, inulin resists hydrolysis by human digestive enzymes and reaches the colon intact where it is selectively fermented by beneficial gut microbiota such as Bifidobacteria and Lactobacilli, producing short-chain fatty acids. This prebiotic activity supports gut health, improves mineral absorption, and modulates blood glucose and lipid levels. In food applications, inulin acts as a fat mimetic, texture enhancer, and low-calorie sweetener due to its gel-forming properties in aqueous systems. Chemically stable under acidic conditions at moderate temperatures, it is widely utilized in functional foods and pharmaceuticals.