Crispiness is that satisfying crunchy quality in food that makes a slight snapping sound when you bite into it. Fresh potato chips have crispiness. So do crackers, the outer layer of fried chicken, toast straight from the toaster, and the top of a perfectly baked cookie.

Crispiness happens when food loses moisture and develops a dry, firm texture. When bread sits in the toaster, heat drives out water and creates that crisp surface. When vegetables get old and limp in the refrigerator, they've lost their crispiness. You can sometimes restore it by putting them in ice water, which helps firm up their cell walls.

Cooks and food scientists care a lot about crispiness because people love that texture. Fast food restaurants carefully time their fries to maximize crispiness. Cereal makers engineer their products to stay crispy even in milk (at least for a little while).

People sometimes confuse crispiness with crunchiness, but they're slightly different. Crispiness suggests something delicate that shatters easily, like a thin cracker. Crunchiness implies something thicker and sturdier, like a carrot or an apple, that takes more force to break.