Quantum electrodynamics (QED) is a fundamental theory in physics that describes how light and matter interact. It combines the principles of quantum mechanics and electromagnetism, focusing on the behavior of particles like electrons and photons. QED explains phenomena such as the emission and absorption of light by atoms. In QED, particles are treated as excitations of underlying fields. For example, photons are the force carriers of the electromagnetic field, while electrons interact with these photons. This framework allows physicists to make precise predictions about various processes, such as the scattering of light and the behavior of charged particles.