The primary building block of radio communications is a radio wave. The most popular application of radio waves is for communication. Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies as high as 300 gigahertz to as low as 30 hertz. At 300 GHz, the corresponding wavelength is 1 mm, and at 30 Hz is 10,000 km. Radio waves have the longest wavelengths in the electromagnetic spectrum. They range from the length of a football to larger than our planet. Radio waves are used in almost all forms of wireless communication, and we certainly utilize them every day.