A world war is a war affecting the majority of the world's major nations. World wars usually span multiple continents, and are very bloody and destructive.
The term has usually been applied to two conflicts of unprecedented scale and slaughter that occurred during the 20th century. They were the First World War, also known as the Great War (1914–1918) and the Second World War (1939–1945).
 Origins of the term
The term "World War" was coined speculatively in the early 20th century, some years before the First World War broke out, probably as a literal translation of the German word 'Weltkrieg' The Oxford English Dictionary cites the first known usage as being in April 1909, in the pages of the Westminster Gazette.
It was recognized that the complex system of opposing alliances—German Empire - Austria-Hungary - Italy vs. French Third Republic - Russian Empire - United Kingdom of Great Britain and Ireland - Serbia was likely to lead to a global conflict in the event of war breaking out. The fact that the powers involved had large overseas empires virtually guaranteed that a conflict would be global, as the colonies' resources would be a crucial strategic factor. The same strategic considerations also ensured that the combatants would strike at each others' colonies, thus spreading the fighting far more widely than in the pre-colonial era.
Prior to 1939, the European war of 1914–1918 was usually called either the World War or the Great War. Only after the start of hostilities in 1939 did the World War become commonly known as the First World War. This is easily observed today when visiting the numerous First World War monuments and memorials to be found throughout Europe and North America. Such memorials, most of which were constructed in the 1920s plainly refer to the World War or Great War. Occasionally, a contemporary marker will indicate 1919 as the year the war ended (e.g., The World War, 1914-1919) which refers to the date of the Treaty of Versailles as the official end of the war rather than the Armistice in 1918 which in effect ended the actual hostilities. In 1933, Simon & Schuster published a photographic history of the war, edited by playwright and war veteran Laurence Stallings, with the title The First World War. A feature-length documentary film, also written by Stallings and titled The First World War, was released in November 1934. Three months before World War II began in Europe, Time magazine first used the term "World War I" in its issue of June 12, 1939, when comparing the last war with the upcoming war.
The term "Second World War" was also coined in the 1920s. In 1928, US Secretary of State Frank B. Kellogg advocated his treaty "for the renunciation of war" (known as the Kellogg-Briand Pact) as being a "practical guarantee against a second world war". The term came into widespread use as soon as the war began in 1939. Time magazine introduced the term "World War II" in the same article of June 12, 1939, in which it introduced "World War I," three months before the start of the second war.
Other languages have also adopted the "World War" terminology; for instance, in French, the two World Wars are the Guerres Mondiales; in German, the Erste und Zweite Weltkrieg; in Russian the мировые войны; and so on.
 Earlier worldwide conflicts
Other examples suitable to be classified as world wars in terms of their intercontinental and intercultural scope were the Mongol Invasions leading to the Mongol Empire, which spanned Eurasia from China, Japan, and Korea to Persia, Mesopotamia, the Balkans, Hungary and Russia, and the Dutch-Portuguese War from the 1580s to the 1650s, which was fought throughout the Atlantic, Brazil, West Africa, Southern Africa, the Indian Ocean, India and Indonesia.
Dutch-Portuguese war, the first intercontinental resource war.
Other wars in earlier periods that saw conflict across the world have been considered world wars by some, including the War of the Spanish Succession (1701-1713)Seven Years' War (1756–1763); Winston Churchill called it "the first world war" in A History of the English-Speaking Peoples, the French Revolutionary Wars (1792–1802) and the Napoleonic Wars (1803–1815). These, however, were confined to the European powers and their colonial empires and offshoots. The Asian powers were not involved (counting the Ottoman Empire as a European power in this instance).
Prior to the late 19th century, the concept of a world war would not have had much meaning. The Asian powers of China and Japan did not act outside their own continents, and they certainly did not conduct affairs on an equal footing with the European powers; China was the target of European colonialism while Japan remained isolationist until the 1850s. The European conflicts of earlier centuries were essentially quarrels between powers which took place in fairly limited, though sometimes far-flung, theaters of conflict.
Where native inhabitants of other continents were involved, they generally participated as local auxiliaries rather than as allies of equal status, fighting in multiple theaters. For instance, in Britain's wars against France, Native Americans assisted both European powers on their own ground rather than being shipped to continental Europe to serve as allied troops there. By contrast, during the World Wars, millions of troops from Africa, Asia, North America and Australasia served alongside the colonial powers in Europe and other theatres of war.
 Characteristics of the World Wars
The two World Wars of the 20th century took place on every continent on Earth save Antarctica, with the bulk of the fighting taking place in Europe and Asia. They involved more combatant nations and more individual combatants than any other conflicts.
The World Wars were also the first wars to be fought in all three terrestrial elements—ground, sea and air—and depended, more than in any previous conflict, on the mobilization of industrial and scientific resources. They were the first instance in which the doctrine of total war was fully applied, with drastic effects on the participants.
Many of the nations who fought in the First World War also fought in the Second, although not always on the same sides. Some historians have characterized the World Wars as a single "European civil war" spanning the period 1914–1945. This is arguably an oversimplification, as the European aspect of the Second World War might never have happened had Adolf Hitler not come to power. It also overlooks the war in the Far East caused by Japan's programme of territorial expansion, which started independently of events in Europe.
The World Wars were made possible, above all else, by a combination of fast communications (such as the telegraph and radio) and fast transportation (the steam ship and railroad). This enabled military action to be coordinated rapidly over a very wide area and permitted troops to be transported quickly in large numbers on a global scale.
 Effects of the World Wars
The two World Wars of the 20th century caused unprecedented casualties and destruction across the theaters of conflict. The numbers killed in the wars are estimated at between 60 and 100 million people. Unlike in most previous conflicts, civilians suffered as badly as or worse than soldiers, and the distinction between combatants and civilians was often erased.
Both World Wars in comparison (estimated data)
||World War I
||World War II
||4 M km²
||22 M km²
The outcome of the World Wars had a profound effect on the course of world history. The old European empires collapsed or were dismantled as a direct result of the wars' crushing costs and in some cases the defeats of imperial powers. The modern international security, economic and diplomatic system was created in the aftermath of the wars. Institutions such as NATO, the United Nations and the European Union were established to "collectivise" international affairs, with the explicit aim of preventing another outbreak of general war. The wars also greatly changed the course of daily life. Technologies developed during wartime had a profound effect on peacetime life as well—for instance, jet aircraft, penicillin, nuclear energy and electronic computers.
Since the Second World War was ended in August 1945 by the atomic bombings of Hiroshima and Nagasaki, there has been a widespread and prolonged fear of a Third World War between nuclear-armed superpowers. The fact that this has not come to pass has been attributed by many to the devastating and essentially unwinnable nature of nuclear warfare, with the end result being the extermination of human life or, at the very least, the collapse of civilization.
When asked what kind of weapons would be used to fight World War III, the physicist Albert Einstein replied:
- I don't know with what weapons World War III will be fought, but World War IV will be fought with sticks and stones.
 Subsequent world wars
Some groups define "world war" such that the Cold War should be termed a world war. Others claim that the current "War on Terrorism" is a world war. The Project for the New American Century holds both views, calling the Cold War "World War III" and the War on Terrorism "World War IV", this was also agreed by Jean Baudrillard. However, these characterizations have attracted little support and have not been agreed upon by the majority of historians.
- ^ Online Etymology Dictionary entry for World War
- ^ "War Machines," Time, June 12, 1939.