What is Cold War (1945-1991) ?
After World War 2, the United States and the Soviet Union became the two Superpowers. Both countries had large populations, great armies, abundant resources and advanced technological know-how. Their relations became cool soon after the World War 2 because of their disagreements about the future of the world although they were allies during the war.
The world was gradually divided into two sides in the post-war period which are the capitalist bloc and the communist bloc leading by the United States and USSR (Soviet Union) respectively. The open hostility between the two sides resulted in serious international crisis. The world entered into a new era calling the Cold War.