Cornstarch is a fine, powdery substance derived from the starchy part of corn kernels. It is widely used in cooking as a thickening agent for soups, sauces, puddings, and gravies. Cornstarch is also used in baking, as it helps to create a light, airy texture in certain baked goods. It is tasteless, odorless, and gluten-free, making it an essential ingredient in many gluten-free recipes.