The Cold War was a period of tension from about 1947 to 1991 between two major powers: the United States and the Soviet Union. These countries had different political systems and competed for global influence.

Instead of fighting each other directly, they supported different sides in conflicts around the world. This included wars in places like Korea and Vietnam. Both sides built large numbers of nuclear weapons and tested them over time.

The period also included the Space Race, where both countries competed to explore space, including the first human in space in 1961 and the Moon landing in 1969. The world was often divided into opposing political groups. The Cold War ended in 1991 when the Soviet Union broke apart.