In physics, the photon is an elementary particle, the quantum of the electromagnetic field and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force. This force's easily visible human-scale effects and applications, from sunlight to radiotelephones, are because the photon has no mass and thus can produce interactions at long distances. Like all elementary particles, the photon is governed by quantum mechanics and so exhibits wave-particle duality: that is, it exhibits both wave and particle properties. For example, a single photon may undergo refraction by a lens or exhibit wave interference, but also act as a particle giving a definite result when its location is measured.
|Includes CC-BY-SA content from Wikipedia's Photon article (authors)|