World war

United States Army infantry supported by a M18 tank destroyer advancing through an enemy-occupied town during World War II, the most recent conflict to widely be considered a "world war".

A world war is an international conflict in which most of the countries in the world fight or help.

There have been two World Wars so far, World War I (1914-1918), and World War II (1939-1945), Several earlier historical wars such as the Anglo-Dutch Wars and American Revolutionary War were fought in many places around the world, but they were wars among European empires.

After World War II, many people were scared that a World War III might start from the Cold War between the United States and Western Bloc on one side and the Soviet Union and Eastern Bloc on the other. After World War II, countries had many powerful weapons, including jet bomber airplanes, which could carry nuclear weapons to destroy many buildings and kill many people instantly, far away; and much faster missiles which could also carry nuclear weapons.

German physicist Albert Einstein is supposed to have said, "I don't know what weapons countries might use to fight World War 3, but wars after that will be fought with sticks and stones". After the end of the Soviet Union, people were less afraid that World War III would begin.