Cold War: A period between 1945 and 1991 characterized by political tension and rivalry between the United States (capitalist) and the Soviet Union (communist), resulting in indirect conflicts around the world.
Iron Curtain: A metaphorical division between Eastern Europe (under Soviet influence) and Western Europe (not under Soviet influence) during the Cold War.
Domino Theory: The belief that if one country falls under communist control, neighboring countries would also follow suit like falling dominoes.