Light is a form of electromagnetic radiation that is very familiar to us. However, there are several other forms of electromagnetic (EM) radiation, such as X-rays, radio waves, and ultraviolet and infrared “light”. Together, these different types of EM radiation make up the electromagnetic spectrum.
Each section of the electromagnetic (EM) spectrum has characteristic energy levels, wavelengths, and frequencies associated with its photons. Gamma rays have the highest energies, the shortest wavelengths, and the highest frequencies. Radio waves, on the other hand, have the lowest energies, longest wavelengths, and lowest frequencies of any type of EM radiation. In order from highest to lowest energy, the sections of the EM spectrum are named: gamma rays, X-rays, ultraviolet radiation, visible light, infrared radiation, and radio waves. Microwaves (like the ones used in microwave ovens) are a subsection of the radio wave section of the EM spectrum.
source: windows to the universe