Proletariat: In Marxist theory, this term refers to the working-class people regarded collectively.
Bolsheviks: A faction of the Marxist Russian Social Democratic Labour Party which eventually became the Communist Party of the Soviet Union after seizing power in Russia during October Revolution (1917).
Cold War: A period of geopolitical tension between powers in Eastern Bloc (Soviet Union and its satellite states) and powers in Western Bloc (United States, NATO allies) post World War II; Communism vs Capitalism was one of major ideological conflicts during this period.