War is a large-scale and organized use of force, typically between states or between a state and a non-state actor, with the aim of achieving political or military objectives. War can take many forms, including conventional warfare, guerrilla warfare, and civil war, and can result in significant loss of life and destruction of property. War is a central concern in the study of International Relations, and the causes and consequences of war have been widely debated by scholars and policymakers.
Source: Clausewitz, C. von. (1832). On War. London: N. Trübner & Co.