Electrodynamics, also referred to as classical electrodynamics, is the study of the interactions between electrically charged objects and electric fields. On scales where quantum effects are negligible or can be ignored, electrodynamics provides a very good approximation of electrical and magnetic phenomena. On finer scales, quantum electrodynamics is a better approximation.
The study of Electrodynamics began with Coulomb's Law, which is similar to Newton's law of Gravitation. Maxwell equations introduced magnetism in the first unification theory, making electric forces and magnetism two aspects of the same fundamental force (the electromagnetic field). The fact that Maxwell equations didn't behave correctly when transformed using Galileo's relativity equations was a motivation for Einstein's Special theory of relativity, since Lorentz transformation preserved the form of Maxwell equations.