World War 2 involved the actions of The United Kingdom, the United States, Japan, and Germany Withe the British and Americans being the allies while Germany and Japan were the Axis.
The events of WW 2 took place across the globe. Most of the combat action took place in Europe, East Asia, and Islands in the Pacific ocean.
Although each regional war began for different reasons it is generally agreed that WW2 started because of axis aggression.
The first regional war within WW2 began in July 7, 1937 when Japan invaded China. Germany capitulated on May 7, 1945 after soviet troops invaded Berlin, Emperor Showa announced the intention for the Japanese Surrender on August 14, 1945. A treaty was signed officially ending WW2 in September 1951.
Some WW2 legacies still impact our lives today. For example the Japanese government still faces criticism for its atrocities committed by the war time regime.