Polysaccharides such as mucilage are high-molecular-weight carbohydrates formed by polymerization of monosaccharide units via glycosidic linkages. Mucilage represents a subclass of hydrophilic polysaccharides that swell in water to form viscous gels or colloidal solutions. These compounds occur naturally in plant seeds, roots, and bark (e.g., psyllium, okra, flax), functioning in water retention and seed dispersal. Structurally they contain repeating residues of glucose, galactose, arabinose, xylose, and uronic acids. In food science they act as thickeners, stabilizers, and emulsifiers; in pharmacology they exhibit demulcent, laxative, and hypoglycemic effects. Their solubility and viscosity depend on degree of branching, molecular weight, and presence of charged groups. They are generally non-digestible by human enzymes but may be fermented by gut microbiota.