Quantum electrodynamics (QED) is the relativistic quantum field theory that describes the electromagnetic interactions between charged particles. It combines quantum mechanics with special relativity to explain the behavior of photons (the fundamental particles of electromagnetic radiation) and charged particles such as electrons and positrons. QED is one of the most successful and well-tested theories in physics, providing accurate predictions for phenomena such as the Lamb shift, the anomalous magnetic moment of the electron, and the scattering of light by matter. It also serves as the basis for the Standard Model of particle physics, which describes the interactions of all known elementary particles and forces (except gravity). Overall, quantum electrodynamics plays a crucial role in our understanding of fundamental interactions in nature and has far-reaching applications in areas such as quantum computing and the development of new technologies.