The system of economic and political ideas first developed by Karl Marx and Friedrich Engels and later developed by their followers together with dialectical materialism to form the basis for the theory and practice of communism. At the heart of Marxism lies the materialist conception of history, according to which the development of all human societies is ultimately determined by the methods of production that people adopt to meet their needs. A particular technique of production determines a set of property relations to organize production (for instance slavery, feudalism, capitalism), as well as the politics, religion, philosophy, and so on of a given society. The conflict between the particular social classes that emerged led to the next stage of social evolution. Feudalism had been followed by capitalism, which was destined to make way for socialism/communism. In this way Marx and Engels sought to establish the importance of the class struggle. Their attention was focused on capitalist societies, which they viewed as increasingly polarized between an exploiting capitalist class and an impoverished working class. Crucial to Marx’s economic analysis of capitalism was his elaboration of the labour theory of value held by the classical economists Smith and Ricardo. Marx saw capitalists as expropriating the surplus value created by workers, and accumulating ever-increasing amounts of capital, as the workers (the proletariat) grew ever poorer. The development of industry would render capitalism obsolete, at which point the working class would be ready to overthrow the system by revolutionary means and establish a socialist society. Marx and Engels said little about the economics and politics of socialism; after their death, Lenin and his followers in the former Soviet Union and elsewhere used Marxist ideas to underpin communism, the ideology later being dubbed ‘Marxism-Leninism’, while other Marxists were critical of communist methods and regarded the Russian revolution (1917) as premature. Since then Marxists have had to grapple with the failure of the socialist societies to live up to the humanistic beliefs of Marx himself, and also with political developments, such as the rise of fascism, that appeared to contradict historical materialism. Marxism-Leninism as practised in the USSR, and in other countries of the Soviet bloc, collapsed in the 1990s, when the command economy on which it was based was replaced by a market economy. In spite of this practical failure of Marxism, Marx’s injunction that to understand a society we should first investigate its mode of production continues to influence many social scientists.