The Cold War is the name for the time period of fear of war between the United States of America and the Soviet Union that dominated political and social thinking for several decades during the 20th century. The conflict pitted the United States and its allies on one side against the USSR with its allies on the other. The duration of the Cold War is disputed. For some observers it began with the response of the Western Powers to the Russian Revolution in 1917. London, Paris and Washington sought to isolate and topple the new Bolshevik government of Russia after it withdrew from the disastrous First World War. Other observers date it as beginning in 1947, in the decision of the Truman administration to assist the anti-communist royalist government of Greece against Greek communist insurgents. lasted for about 50 years, beginning well before World War II, and lasting until the end of the Soviet Republic. The height of the Cold War could be said to have occurred during the 1950s through the 1970s. During this time many people feared that World War III could start and they, their families and friends could be killed. The two Superpowers of the time tried to outdo each other militarily, industrially and through Propaganda.
In the Western world the Cold War was seen as a struggle between good democracy and evil Communist Dictatorship and Totalitarianism. Most Western European countries became allies of the United States while Eastern European countries became Communist dictatorships and allies of the Soviet Union. The division between them was called the Iron Curtain which ran across Europe from north to south splitting Germany into East and West Germany. The term, Iron Curtain, also had a much deeper meaning in the west. It became a symbol of the secrecy and fear propagated by the communist agenda. In the U.S., fear of "the reds" bred paranoia which led to McCarthyism.
There were euphemism police actions and wars in foreign countries which American and Free world propaganda portrayed as containment of Communism. Communist propaganda saw these same conflicts as the USSR furthering its "glorious Communist revolutions". At first, containment failed and communism gradually spread. Later, as the economic weakness of Communism took its toll, the western allies could contain and rollback communism. Many former communist countries are now democracies or non-communist dictatorships. Much of this reversal was accomplished slowly through economic and political reform - not by military action.