Wavelength: 10-3m to 10-1m
Special electrical circuits (klystron, magnetron).
Resonance in similar special electrical circuits (also klystron, magnetron).
Greatly used in air-borne communications, for example with mobile phones. The shorter the wavelength the greater the bandwidth. Microwaves are also used in point to point "beaming" of energy, it has been suggested that orbiting power satellites could simply "beam" the energy produced to earth based stations via microwave links. However this is still only theory since security precautions would have to be considered to prevent these satellites from being hijacked and turned against civilian areas for the purpose of frying people.
Note the size of these wavelengths - the longer microwaves' wavelengths are literally measured in centimeters. Contrast this with gamma rays, whose wavelengths are sub-atomic in size. Many stars are microwave emitters.