Radios AM or FM, radios are the most common wireless communications device on the face of the planet. We take them for granted, these little radios, finding them playing in cars, homes and offices, tagging along with joggers, tradesmen and teenagers after school.
Radio waves are part of a general class of waves known as electromagnetic waves.
In essence, they are electrical and magnetic energy which travels through space in the form of a wave. The wave part is similar, but the energy involved is electrical and magnetic, not mechanical. At much higher frequencies, we call them infrared light. Still higher frequencies make up the spectrum known as visible light. This goes on up into ultraviolet light, and x-rays, things that radio engineers rarely have to worry about.