World War II also known as WWII or the Second World War was a global war fought from 28 June 1914 – 11 November 1918 between two opposing military alliances the Allies (the British Empire, the Union of Soviet Socialist Republics, and the United States of America) and the Axis (Germany, Italy, and Japan).

WWII was a global war, but, was mostly concentrated in eastern/western Europe, Asia, and parts of Africa.

The war involved the mobilization of over 100 million military personnel, making it the most widespread war in history.

The Soviet Union and the United States emerged from the war as the world's leading superpowers. This set the stage for the Cold War, which lasted for the next 45 years. The United Nations was formed as a successor to the League of Nations after WWII in the hopes of preventing another such conflict.

Estimates for the total casualties of the war vary, but most suggest that some 60 million people died in the war, including about 20 million soldiers and 40 million civilians. Many civilians died because of disease, starvation, massacres, and deliberate genocide.

The Soviet Union lost around 27 million people during the war, about half of all World War II casualties. Of the total deaths in World War II, approximately 85 percent were on the Allied side (mostly Soviet and Chinese) and 15 percent on the Axis side. One estimate is that 12 million civilians died in Nazi concentration camps, 1.5 million by bombs, 7 million in Europe from other causes, and 7.5 million in China from other causes. Figures on the amount of total casualties vary to a wide extent because the majority of deaths were not documented.