What are Microwaves...

Microwaves are the power behind the microwave oven.  They are electromagnetic waves with wavelengths in the centimeter range and a frequency domain of 10⁹ to 3 x 10¹¹ Hz.  This frequency is what makes the microwave so useful.  For one it is what "heats" up your food in the microwave and can easily penetrate the Earth's atmosphere, which allows for an easy means of communication with space-vehicles.

www.bbc.co.uk/science/hottopics/mobilephones/images/em_spetrum.jpg