Classical Electrodynamics
Classical electrodynamics is the study of electric and magnetic phenomena governed by Maxwell's equations. Formulated by James Clerk Maxwell in the 1860s, these four partial differential equations describe how electric fields, magnetic fields, electric charges, and currents interact and propagate.
Maxwell's unification of electricity and magnetism revealed that light is an electromagnetic wave — a propagating disturbance in the electromagnetic field. This insight established that optics, electricity, and magnetism are aspects of a single physical framework, and it set the stage for both special relativity and quantum field theory.
Classical electrodynamics remains the correct description of electromagnetic phenomena at scales where quantum effects are negligible. It is the prototype of a field theory: a physical theory in which the fundamental quantities are fields — continuous distributions of values across space and time — rather than particles.