Anti-communism is political and ideological opposition to communist beliefs, groups, and individuals. Organized anti-communism developed after the 1917 October Revolution in Russia, and it reached global dimensions during the Cold War, when the United States and the Soviet Union engaged in an intense rivalry. Anti-communism has been an element of many movements with different political positions across the political spectrum, including anarchism, centrism, conservatism, fascism, liberalism, nationalism, social democracy, socialism, leftism, and libertarianism, as well as broad movements resisting communist governance. Anti-communism has also been expressed by several religious groups, and in art and literature.