The photon is the gauge boson that carries the electromagnetic force.
In quantum electrodynamics, electromagnetic interactions are described through the exchange of photons. A photon has zero rest mass, no electric charge, and two physical polarization states. In vacuum it travels at the speed of light, while its energy is related to frequency by Planck’s equation, E = hf.
Photons are also the quantum units of electromagnetic radiation, including radio waves, visible light, X-rays, and gamma rays. The same theory treats light as both a quantized field and a wave with interference and diffraction. A common mix-up is calling every force carrier a photon: gluons carry the strong interaction, W and Z bosons carry the weak interaction, and no experimentally confirmed graviton exists.