After the end of World War 2, two superpowers emerged as they had come out of the war very strong. These two superpowers were the USA and the USSR. The USA believed in the capitalist system while the USSR believed in the communist system of government.
These superpowers were very hostile towards each others different system of government, thus creating the 'Cold War'. This 'Cold War' did not include any direct fighting on the behalf of the superpowers, due to the risk of a nuclear war, but rather they jockeyed for power using countries as puppets.
An example is Czechoslovakia, which was liberated by the Russians in 1945. The Russians set up political parties within the Czech government and because the Czech's were grateful towards the Russians, they voted for the communist party. By 1948 there were still unresolved economic difficulties and communism was losing popularity. These may have been overcome by taking advantage of the Marshall Plan, which they refused.
The communists feared losing power in forthcoming elections, so they seized power in a coup. Russia took this as a sign of strengthening and became maybe over-confident.
One of the major issues raised after the war was the fate of Germany. It was decided that it would be split into four zones: Soviet, USA, Britain and France. These were controlled under an Allied Control Council. Berlin was also split up into 4-power control but it was buried deep in the Russian zone.
The first major crisis over Berlin was the blockade. There were several factors which caused the blockade. Russia was embarrassed because it had drained all of the East's resources while the British and Americans had built up the West. The Russians were also annoyed by the fact that there was an island of capitalism in...