War is a state of armed conflict between societies. It is generally characterized by extreme collective aggression, destruction, and usually high mortality. The set of techniques and actions used to conduct war is known as warfare. An absence of war is usually called "peace".  Total war is warfare that is not restricted to purely legitimate military targets, and can result in massive civilian or other non-combatant casualties.

In software engineering, a WAR file (or Web application ARchive) is a JAR file used to distribute a collection of JavaServer Pages, Java Servlets, Java classes, XML files, tag libraries, static web pages (HTML and related files) and other resources that together constitute a web application.

War is a large-scale armed conflict and the term is used as a metaphor for non-military conflicts.