World War 2 was a war fought from 1939 to 1945 in Europe and also in Asia.
The war in Europe began on the 1st of September, 1939 with the invasion of Poland by Nazi Germany, and concluded on September 2, 1945, with the official surrender of the last Axis nation, Japan. However, in Asia the war began earlier with Japanese interventions in China, and in Europe, the war ended earlier with the unconditional surrender of Germany on May 8, 1945. The conflict also occurred over into Africa.
It was the largest armed war in history, involving more countries than any other war, as well as introducing powerful new chemical weapons.
In total, World War II produced around 50 million deaths, a horrifying number. More than any other war to date.