Cellulose is a linear polysaccharide composed of β-1,4-linked D-glucose units forming the primary structural component of plant cell walls. As dietary fiber, it is indigestible by humans due to the absence of cellulase enzymes, contributing to gut health by increasing fecal bulk and modulating glucose absorption. It exhibits high tensile strength from extensive hydrogen bonding between chains, forming crystalline microfibrils. In food applications, cellulose derivatives like microcrystalline cellulose serve as thickeners and stabilizers. Chemically inert and hydrophilic yet water-insoluble, it resists degradation in most solvents and is biodegradable by microbial cellulases in the environment.