A wave is a form of motion which can appear in many forms. Though we are most familiar with waves in water, there are also sound waves, light waves, radio waves and electromagnetic waves.
Waves are large-scale coordinated disturbances.
While the medium in which a wave travels does not necessarily move as a whole in the direction of the wave, the wave creates small-scale motion in the medium. Just as a water wave lifts swimmers up and sets them down as it passes, plasma waves can shift a net electrical charge in plasma from one ionospheric region to another. Similarly, plasma and electromagnetic waves transfer energy between electrons, ions, and neutral particles. Scientists are very interested in how energy is exchanged between ionospheric and atmospheric layers. A plasma also may emit and absorb light, radio, and other electromagnetic waves created by shifting electric and magnetic fields.