A microwave oven is a kitchen appliance that uses electromagnetic waves to heat or cook food quickly and efficiently. It works by generating microwaves, which are a type of electromagnetic radiation, in a chamber inside the oven. These microwaves penetrate the food, causing water molecules in the food to vibrate rapidly, creating friction and heat. This process heats up the food from the inside out, allowing it to cook quickly without damaging its texture or nutrients. Microwave ovens are popular for their convenience and speed, making them a common appliance found in many households today.