A thickener is a substance added to a liquid or food to make it thicker or more dense. It is commonly used in cooking and food production to improve the texture of soups, sauces, and other dishes. There are many different types of thickeners, including natural ones like flour and cornstarch, as well as synthetic ones like sodium carboxymethyl cellulose, xanthan gum, and sodium alginate. Thickeners give foods a smoother, more pleasing texture and help them hold together better.