A theory that describes a field in terms of classical physics rather than quantum mechanics. Examples of classical field theories include classical electrodynamics, described by Maxwell's equations, and the general theory of relativity, describing classical gravitation. A classical field theory emerges as a limit of the corresponding quantum field theory. In order for a classical field theory to apply on a macroscopic scale it is necessary for the interactions to be long range, as they are in electrodynamics and gravitation, rather than short range, as in nuclear forces. Classical field theory is also used for mathematical convenience to describe the physics of continuous media, such as fluids.