Microwave processes rely heavily, and almost exclusively, on the material which is being processed. As with a kitchen microwave unit heating a cup of water, for example, it is dipolar motions within the water that’s responsible for generating heat which in turn processes the water as shown in figure "Dipole heating". Basically the dipoles attempt to align with the applied field as those motions relax, heat is generated via molecular friction.

Microwaves are electromagnetic energy (with electric and magnetic components, shown below) having a frequency range between 0.3 and 300 gigahertz (Ghz). Microwave frequencies are higher than radio wave frequencies and lower than the frequencies of infrared and visible light. Microwaves were first used as a technology in World War II with the advent of radar systems and currently microwave is most notably used in wireless communications, as well as the food processing appliance, the microwave oven.