A radio wave is an invisible form of energy that travels through air and space at the speed of light, carrying information like sounds, pictures, or data from one place to another. Radio waves make it possible for you to listen to music in a car, watch television, talk on a cell phone, or connect to WiFi.

Radio waves are part of the electromagnetic spectrum, the same family of energy that includes visible light, microwaves, and X-rays. In the early 1900s, inventors figured out how to encode sound into these waves and then decode them back into sound at a receiving device.

Here's how they work: A transmitter converts information (like a voice or song) into radio waves and sends them out through an antenna. These waves spread out in all directions, traveling through walls, clouds, and even the vacuum of space. A receiver with its own antenna picks up these waves and converts them back into the original information.

Radio waves vary in length from about a millimeter to over 100 kilometers. Different lengths work better for different purposes: FM radio stations use waves about three meters long, while cell phones use much shorter waves. When you tune a radio to a specific station, you're selecting one particular wavelength from among thousands broadcasting simultaneously.