War

A man plays an instrument during the Bosnian war.

Atomic cloud over Hiroshima

War is an armed conflict between armies or militias of two or more nations or countries. It may include numerous battles, organized into campaigns. A war ends either when one side surrenders (lays down its arms) or the sides negotiate a truce through diplomacy.

Many people are the casualties of war, either killed or wounded. This includes fighters, called "soldiers" or "troops," and civilians, who are "non-combatants." Targeting civilians is a "war crime." Some weapons of war, such as artillery, tanks, and naval and aerial bombardment, can cause much damage to buildings where people live and work.

War is a reason many people flee a conflict zone and become refugees.

See also:

• Cold War