Communism refers to a conjectured future classless, stateless social organization based upon common ownership of the means of production, and can be classified as a multivariant branch of the broader socialist movement. Communism also refers to a variety of political movements which claim the establishment of such a social organization as their ultimate goal. Early forms of human social organization have been described as "primitive communism." However, communism as a political goal generally is a conjectured form of future social organization which has never been implemented. There is a considerable variety of views among self-identified communists. However, Marxism and Leninism, schools of communism associated with Karl Marx and of Vladimir Lenin respectively, have the distinction of having been a major force in world politics since the early 20th century. Class struggle plays a central role in the theory of Marxism. The establishment of communism is in this theory viewed as the culmination of the class struggle between the capitalist class, the owners of most of the capital, and the working class. Marx held that society could not be transformed from the capitalist mode of production to the communist mode of production all at once, but required a state transitional period which Marx described as the revolutionary dictatorship of the proletariat. The communist society Marx envisioned emerging from capitalism has never been implemented, and it remains theoretical. However, the term "Communism", especially when the word is capitalized, is often used to refer to the political and economic regimes under communist parties which claimed to be the dictatorship of the proletariat.
In the late 19th century, Marxist theories motivated socialist parties across Europe, although their policies later developed along the lines of "reforming" capitalism, rather than overthrowing it. The exception was the Russian Social Democratic Workers' Party. One branch of this party, commonly known as the Bolsheviks and headed by Vladimir Lenin, succeeded in taking control of the country after the toppling of the Provisional Government in the Russian Revolution of 1917. In 1918, this party changed its name to the Communist Party; thus establishing the contemporary distinction between communism and socialism.
After the success of the Red October Revolution in Russia, many socialist parties in other countries became communist parties, owing allegiance of varying degrees to the Communist Party of the Soviet Union (see Communist International). After World War II, regimes calling themselves communist took power in Eastern Europe. In 1949, the Communists in China, led by Mao Zedong, came to power and established the People's Republic of China. Among the other countries in the Third World that adopted a Communist form of government at some point were Cuba, North Korea, Vietnam, Laos, Angola, and Mozambique. By the early 1980s, almost one-third of the world's population lived under Communist states.
Communism carries a strong social stigma in the United States, due to a history of anti-communism in America. Since the early 1970s, the term "Eurocommunism" was used to refer to the policies of communist parties in western Europe, which sought to break with the tradition of uncritical and unconditional support of the Soviet Union. Such parties were politically active and electorally significant in France and Italy. With the collapse of the Communist governments in eastern Europe from the late 1980s and the breakup of the Soviet Union on December 8, 1991, Communism's influence has decreased dramatically in Europe, but around a quarter of the world's population still lives under Communist states.