War is an organized and often prolonged conflict that is carried out by states or non-state actors. It is generally characterized by extreme violence, social disruption, and economic destruction. War should be understood as an actual, intentional and widespread armed conflict between political communities, and therefore is defined as a form of (collective) political violence or intervention. The set of techniques used by a group to carry out war is known as warfare. An absence of war is usually called peace. Described below are some of the wars that have taken place.