A microwave oven is a kitchen appliance that heats food using invisible waves of energy called microwaves. Unlike a regular oven that heats the air around your food, a microwave oven makes the water molecules inside your food vibrate incredibly fast (billions of times per second), and this vibration creates heat from the inside out.

This makes microwave ovens much faster than conventional ovens for many tasks. You can reheat last night's dinner in two minutes instead of twenty. You can melt butter in seconds or make popcorn in a bag without touching a stovetop.

The technology was discovered accidentally in 1945 when an engineer named Percy Spencer noticed that microwaves from a radar machine had melted a chocolate bar in his pocket. The first microwave ovens were enormous and expensive, but by the 1970s, they became common in American homes.

People often just say “microwave” as a shorthand, using it as both a noun (“Put it in the microwave.”) and a verb (“Just microwave it for thirty seconds.”) While microwave ovens are convenient for reheating and certain cooking tasks, they don't brown or crisp food the way regular ovens do, which is why some foods taste better cooked the traditional way.