Thickening is a cooking technique used to increase the viscosity of liquids, making them denser and creamier. Common methods include adding ingredients like flour, cornstarch, or arrowroot mixed with water, which create a paste that can be stirred into soups, sauces, or gravies. This process enhances the texture and flavor of dishes. Another way to thicken liquids is by reducing them through simmering, which evaporates some of the water content. This method concentrates flavors and creates a richer consistency. Beurre manié, a mixture of equal parts flour and butter, is also used to thicken sauces without clumping.