World War II (WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945. It involved the vast majority of the world’s nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis. Axis powers (Germany, Italy, Japan, Hungary, Romania, Bulgaria) versus Allies (U.S., Britain, France, USSR, Australia, Belgium, Brazil, Canada, China, Denmark, Greece, Netherlands, New Zealand, Norway, Poland, South Africa, Yugoslavia).