Summary: In approximately 1500 words the entry offers a general the meaning of the term, distinguishes three understandings in the political science literature, reviews in great detail the ideological roots of communist thoughts, summarizes Marx contribution, and compares the historical developments of communist regimes. Three understandings of the term in the political science literature are distinguished: communism as a form of a political system based on the dominance of the communist party, communism as political movements which attempt to overcome capitalism and are directed against the private ownership of production methods, and communism as an ideology. In a general sense, the term communism embraces all political ideologies and movements that attempt to achieve individual equality without private property. As the entry establishes in detail, the ideological and philosophical historical roots are diverse before Marx attempted to develop a scientific foundation for communism onto which he added with Engels a historical-philosophical foundation. The entry ends with a brief comparison of the development of communist regimes and movements throughout the world.