What particle carries the electromagnetic force?

The particle that carries the electromagnetic force is the photon. In quantum field theory, the photon is the quantum, or smallest detectable excitation, of the electromagnetic field. It mediates interactions between electrically charged particles, including the attraction between opposite charges and the repulsion between like charges.

Photons are elementary particles with no electric charge, no rest mass, and spin 1, making them bosons. In empty space they travel at the speed of light. Visible light is made of photons, but so are radio waves, microwaves, infrared radiation, ultraviolet light, X-rays, and gamma rays; their energies differ according to frequency.

A common mix-up is confusing the photon with the W boson. W and Z bosons carry the weak interaction, while gluons carry the strong interaction. The graviton is a hypothetical particle proposed for gravity and has not been experimentally confirmed. Albert Einstein explained light quanta in 1905, and the name “photon” was introduced by Gilbert N. Lewis in 1926.