World war

United States Army infantry supported by a M18 tank destroyer advancing through an enemy-occupied town during World War II.

Map of the world showing the participants in World War I. Those fighting on the Entente's side (at one point or another) are depicted in green, the Central Powers in orange, and neutral countries in gray.

Allies before the attack on Pearl Harbor   Allies that joined after the attack on Pearl Harbor or after 1942   Axis powers (not including occupied territory)   Neutral powers

The "Three Worlds" of the Cold War era in 1975:

  First World: Western Bloc led by the United States and its allies

  Second World: Eastern Bloc led by the Soviet Union, China (Independent), and their allies

  Third World: Non-Aligned and neutral countries

  NATO

  Trans-Sahara initiative

  Major military operations (as of 2011)
      (Afghanistan • Pakistan • Iraq • Somalia • Yemen)

  Other allies involved in major operations

Major terrorist attacks by al-Qaeda and affiliated groups: (as of 2011)

1. 1998 United States embassy bombings • 2. September 11 attacks • 3. 2002 Bali bombings • 4. 2004 Madrid bombings • 5. 2005 London bombings • 6. 2008 Mumbai attacks

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

There have been four world wars so far, World War I (1914-1918), World War II (1939-1945), the Cold War (1945-1992), and the War on Terror (2001-present).

After World War II, many people were scared that fighting would 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.