The photon carries the electromagnetic force between charged particles. In the Standard Model, photons are the gauge bosons of quantum electrodynamics, the theory describing electromagnetic interactions.
A photon has no electric charge, has zero rest mass, and travels at the speed of light in vacuum. Electromagnetic interactions can be represented as exchanges of virtual photons, while real photons are the detectable quanta of electromagnetic radiation, including visible light, radio waves, X-rays, and gamma rays.
Photons have spin one but are classified as bosons because they obey Bose–Einstein statistics. Unlike massive particles, they have no rest frame. Their energy depends on frequency, and their momentum depends on wavelength.
The photon concept grew from Planck’s quantization work and Einstein’s 1905 light-quantum explanation. Quantum electrodynamics later became one of the most precisely tested theories in physics, with predictions such as the electron’s magnetic moment agreeing extremely closely with experiment.