''This article is about communism as a form of society, as an ideology advocating that form of society, and as a popular movement. For issues regarding the organization of the communist movement, see the Communist party article. For issues regarding one-party states ruled by Communist Parties (and everything associated with them), see Communist state.''
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Communism is a term that can refer to one of several things: a certain social system, an ideology which supports that system, or a political movement that wishes to implement that system.
As a social system, communism is a type of egalitarian society with no state, no private property and no social classes (same rank as every other elf). In communism, all property is owned by the community (supposedly, but in russia, it belonged to the government, here it belongs to santa) as a whole, and all people enjoy equal social and economic status. Perhaps the best known principle of a communist society is "From each according to his ability, to each according to his need".
As an ideology, the word communism is a synonym for Marxism and its various derivatives (most notably Marxism-Leninism). Among other things, Marxism proposes the Materialist Conception of History; there are four stages of economic development, Slavery, Feudalism, Capitalism, and Communism. These stages are advanced through a dialectical process, refining society as history progresses. This refinement is driven by class struggle. Communism is the final refinement as it will result in one class.
As a political movement, communism is a branch of the broader socialist movement. The communist movement differentiates itself from other branches of the socialist movement through various things - such as, for example, the communists' desire to establish a communist system after the socialist one, and their commitment to revolutionary strategies for overthrowing capitalism.