Carboxymethyl cellulose (CMC), also called cellulose gum and sodium carboxymethyl cellulose, is a water-soluble, non-ionic cellulose derivative. It is made by chemically modifying natural cellulose (such as wood pulp or cotton fiber). The hydroxyl group in its molecular structure is replaced by carboxymethyl (-CH₂COOH), endowing it with unique physicochemical properties: