Cornstarch is a fine white powder made from the starchy center of corn kernels. When you mix it with liquid and heat it, something almost magical happens: the mixture thickens into a smooth, glossy texture.

Cooks use cornstarch to thicken sauces, gravies, and puddings. A few spoonfuls can turn thin soup into thick stew or watery fruit juice into pie filling. The powder works because its tiny starch molecules absorb water and swell up when heated, creating that thick consistency.

Cornstarch has some unusual properties that make it fun to experiment with. If you mix it with water in the right proportions, you create something called oobleck (named after a Dr. Seuss story). This strange mixture acts like a liquid when you move your hand through it slowly, but becomes hard like a solid when you punch it or squeeze it quickly. Scientists call this a non-Newtonian fluid.

People also use cornstarch outside the kitchen: as baby powder, to make play dough smoother, or even to help remove grease stains from fabric. It's one of those simple ingredients that turns out to be surprisingly versatile.