Quantum electrodynamics is the quantum mechanical theory describing electromagnetic interactions between charged particles and photons.
Usually abbreviated QED, the theory combines quantum mechanics with special relativity. It treats the electromagnetic field as quantized and describes interactions through the exchange of photons. Electrons and positrons are represented by quantum fields, while photons mediate electromagnetic interactions.
Richard Feynman, Julian Schwinger, and Sin-Itiro Tomonaga developed modern QED during the 1940s. Their work introduced practical methods for calculating measurable quantities, including radiative corrections. QED became famous for its extremely precise prediction of the electron’s anomalous magnetic moment and the Lamb shift.
QED is not the same as quantum chromodynamics, which describes the strong interaction and quarks. It is also different from classical electrodynamics, which treats fields continuously and does not include quantum creation and annihilation of photons.