Cornstarch is just what it sounds like: starch derived from corn. It is ground from the white endosperm at the heart of a kernel of corn. Cornstarch is used as a thickening agent in cooking, a health-conscious alternative to talc, and the main ingredient in a biodegradable plastic. It is also mixed with sugar to make powdered sugar.

In the kitchen, cornstarch can be used as a binder for puddings or similar foods, or as a thickener for sauces, stews, and similar dishes. A simple pudding can be made with milk, cornstarch, and sugar. Cornstarch can form unappetizing clumps in hot water, so if you need to thicken something that is already cooking on the stove, mixing a bit of cornstarch in a glass with cold water before adding it to the pot is advised.

Some people prefer cornstarch-based baby powder to the more traditional talc-based variety, as talc presents health concerns. Though the United States Food and Drug Administration has designated talc as generally recognized as safe (GRAS), talc has been linked to pulmonary complaints and a variety of cancers in some studies. Cornstarch, on the other hand, has never demonstrated a potential toxicity.

One of the most interesting properties of cornstarch, often demonstrated in the elementary classroom, is that it becomes a type of non-Newtonian fluid known as a dilatant when mixed with water. Making a dilatant out of cornstarch is a fun and easy experiment to try at home, especially if you can share it with young children. Mix one part water with one-and-a-half to two parts cornstarch, adding a bit of food color for fun if you wish. The cornstarch-water mixture, sometimes called Oobleck in reference to a Dr. Seuss book, acts as a thick liquid when allowed to sit, but as a solid when force is applied. One can sink a hand into the mixture slowly, but it will not give if one tries to punch it.