A microwave oven is a cooking appliance, which is predominantly used for more rapid cooking and heating than some other forms of heating.
The heat in a microwave oven comes from the excitement of molecules in the food, primary the water molecules (dielectric heating). The waves emitted from a magnetron tube (klystron) are channeled into a shielded metal compartment, where their energy is absorbed by the food molecules, raising their temperature quickly. The molecules in some foods, especially those containing large percentages of fats or oils, can reach a much higher temperature than the boiling point of water. These can heat rather quickly and may spatter.
Popular uses of microwave ovens include heating water for coffee or tea, quickly reheating refrigerated foods, and popping popcorn. The ovens have become a staple appliance in Western kitchens since their invention in 1947. Because the wavelength is the same as early radars, the original microwave from the Raytheon Corporation was called the Radarrange.