The Cold War was a conflict involving half the world, and lasting from 1947 until 1985. It was a confrontation of East vs. West which was very close to becoming an outright war.
After World War II the two main governmental systems each wanted to rule and dominate; the Capitalist/Imperialist and the Communist/Socialist. Both were occupying different sides of Germany (America and Britain on the west side, and Russia on the east side).Both wanted to show the other who would be the major superpower.
As soon as the tension was recognizable, other countries took sides; predictably all of the Americas, Australia, New Zealand, Britain and some East-Asian countries all joined the U.S. The Soviet Union, Mongolia, Cuba, and some West-European countries joined the Communists. Due to the threat of nuclear weapons, most of the world was running scared.
In the second world war, the Soviet Union and the US were allied against Germany.
When the allies had victory, Germany was divided (thanks to the Yalta agreement) mainly into the Soviet sector, the American sector and the British/French sector. The agreement let the Soviets have significant power in Europe, which the British did not fully approve of and the Americans flatly disagreed with (due to their dislike of communism). This mutual dislike of political systems posed a major threat to the peace between the two powers.
As the Soviets and their communist allies established their new borders, Great Britain and the US became increasingly weary of the communist's desire for more European control. To help repair the huge damage wrought on Eurasia, the US started pushing capitalism in Europe, and founded the World Bank and the International monetary fund, both of which the Soviet Union did not join. When President Truman refused to give the Soviet Union recompense from West Germany's...