Communism is a political and economic ideology that advocates for a classless society where all property is publicly owned. In this system, the means of production, such as factories and farms, are controlled by the community or the state, aiming to eliminate private ownership and reduce economic inequality. The theory of communism was developed by Karl Marx and Friedrich Engels in the 19th century, particularly in their work, the Communist Manifesto. Countries like the Soviet Union and China have implemented communist principles, although the outcomes and practices have varied significantly from the original ideology.