Wave propagation refers to any of the ways in which waves travel.
- Electromagnetic radiation propagates through space, carrying electromagnetic energy in the form of electromagnetic waves.
- The propagation of electromagnetic radiation through space is sometimes described in terms of photons rather than waves.
- Photons are particles that are sometimes used to explain the behaviour of electromagnetic waves.
- Propagation of electromagnetic waves can occur in a vacuum as well as through different media. Other wave types such as sound waves cannot propagate through a vacuum and require a transmission medium.
- All forms of electromagnetic radiation propagate in similar ways whether they are radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, or gamma rays.