An electromagnetic wave is formed when an electric field couples with a magnetic field. The magnetic and electric fields of an electromagnetic wave are perpendicular to each other and to the direction of the wave.
Electromagnetic waves transport energy and, unlike ocean waves, can travel through space without the need for wires or a physical medium. They include not only radio waves, but also infrared light, visible light, and X-rays, among others. The type of wave, along with its properties, depends on the frequency at which it oscillates.
- "Overview" section: 5G Wireless: Capabilities and Challenges for an Evolving Network, at 5.