Cook means to prepare food by heating it. When you cook dinner, you might boil pasta, fry an egg, bake cookies, or grill a hamburger. Cooking changes food: heat makes raw chicken safe to eat, turns cake batter into an actual cake, and transforms hard rice grains into something soft and delicious.

People have cooked food for hundreds of thousands of years, ever since humans learned to control fire. Cooking makes many foods easier to digest, kills harmful bacteria, and creates amazing flavors and textures that raw ingredients don't have. A carrot tastes very different raw than when it's roasted until sweet and caramelized.

The word also appears in useful expressions. When someone really excels at something, you might say now you're cooking! If someone is cooking up a plan, they're creating or inventing something (not necessarily food). And when something is cooked, it can mean it's ruined or finished, like when you leave cookies in the oven too long and they're completely cooked.

A cook is also a person whose job involves preparing food, whether in a restaurant kitchen, a school cafeteria, or on a ship.