A food thickener is a substance used to increase the viscosity of liquids, making them thicker and more stable. Common thickeners include cornstarch, gelatin, and xanthan gum. They are often used in cooking and food preparation to improve texture and mouthfeel in sauces, soups, and desserts. Thickeners can be derived from natural sources, such as plants and seaweed, or can be synthetic. They play a crucial role in the food industry, helping to create products with desirable consistency and preventing separation of ingredients. Proper use of thickeners can enhance the overall quality of a dish.