This article has been excerpted from Wikipedia (https://en.wikipedia.org/wiki/War)

Definition of war

War is intense armed conflict between states, governments, societies, or paramilitary groups such as mercenaries, insurgents, and militias. It is generally characterized by extreme violence, aggression, destruction, and mortality, using regular or irregular military forces. Warfare refers to the common activities and characteristics of types of war, or of wars in general. Total war is warfare that is not restricted to purely legitimate military targets and can result in massive civilian or other non-combatant suffering and casualties.
The scholarly study of war is sometimes called polemology (/ˌpɒləˈmɒlədʒi/ POL-ə-MOL-ə-jee), from the Greek polemos, meaning war, and -logy, meaning the study of.
While some scholars see war as a universal and ancestral aspect of human nature, others argue it is a result of specific socio-cultural, economic, or ecological circumstances.

Etymology

The English word war derives from the 11th-century Old English words wyrre and werre, from Old French werre (also guerre as in modern French), in turn from the Frankish *werra, ultimately deriving from the Proto-Germanic *werzō mixture, confusion. The word is related to the Old Saxon werran, Old High German werran, and the German verwirren, meaning “to confuse”, “to perplex”, and “to bring into confusion”.

Types of warfare

Asymmetric warfare is a conflict between belligerents of drastically different levels of military capability or size.Biological warfare, or germ warfare, is the use of weaponized biological toxins or infectious agents such as bacteria, viruses, and fungi.Chemical warfare involves the use of weaponized chemicals in combat. Poison gas as a chemical weapon was principally used during World War I, and resulted in over a million estimated casualties, including more than 100,000 civilians.Cold warfare is an intense international rivalry without direct military conflict, but with a sustained threat of it, including high levels of military preparations, expenditures, and development, and may involve active conflicts by indirect means, such as economic warfare, political warfare, covert operations, espionage, cyber warfare, or proxy wars.Conventional warfare is declared war between states in which nuclear, biological, or chemical weapons are not used or see limited deployment.Cyberwarfare involves the actions by a nation-state or international organization to attack and attempt to damage another nations information systems.Insurgency is a rebellion against authority when those taking part in the rebellion are not recognized as belligerents (lawful combatants). An insurgency can be fought via counter-insurgency warfare, and may also be opposed by measures to protect the population, and by political and economic actions of various kinds aimed at undermining the insurgents claims against the incumbent regime.Information warfare is the application of destructive force on a large scale against information assets and systems, against the computers and networks that support the four critical infrastructures (the power grid, communications, financial, and transportation).Nuclear warfare is warfare in which nuclear weapons are the primary, or a major, method of achieving capitulation.Total war is warfare by any means possible, disregarding the laws of war, placing no limits on legitimate military targets, using weapons and tactics resulting in significant civilian casualties, or demanding a war effort requiring significant sacrifices by the friendly civilian population.Unconventional warfare, the opposite of conventional warfare, is an attempt to achieve military victory through acquiescence, capitulation, or clandestine support for one side of an existing conflict.