The role of photons
Photon is the basic particle that transfers electromagnetic interaction and is a gauge boson. Photons are carriers of electromagnetic radiation, and in quantum field theory photons are considered to be mediators of electromagnetic interaction. Compared with most elementary particles, the rest mass of a photon is zero, which means that its propagation speed in vacuum is the speed of light. Like other quantum, photons have wave-particle duality: photons can exhibit the properties of refraction, interference, and diffraction of classic waves; and the particle nature of photons can be proved by the photoelectric effect. Photons can only transfer quantized energy, are lattice particles, and are the mass-energy phase states of quantum particles.