While never rigorously defined and changing in character over time, combat is the confrontation of military forces where one intends to dominate the other, usually with lethal force. Combat is a physical activity, distinct from the legal status of war.
Early combat was exclusively by lethal weapons, at close range and often powered by human muscle. With the introduction of technology, combat ranges increased, eventually to intercontinental distances. The "kinetic" forces began to be complemented by nonkinetic information operations including electronic warfare and psychological operations.
The earliest combat was among tribal societies, but it evolved to nation-states. Today, however, non-national actors may be opponents, especially in land warfare. Sea, air, and space combat remain principally the domain of nations.