Karl Heinrich Marx (5 May 1818 – 14 March 1883) was a German philosopher, sociologist, historian, political economist, political theorist and revolutionary socialist, who developed the socio-political theory of Marxism. His ideas have since played a significant role in the development of social science and the socialist political movement. He published various books during his lifetime, with the most notable being The Communist Manifesto (1848) and Capital (1867–1894), many of which were co-written with his friend, the fellow German revolutionary socialist Friedrich Engels.
Born into a wealthy middle class family in Trier, Prussia, Marx went on to study at both the University of Bonn and the University of Berlin, where he became interested in the philosophical ideas of the Young Hegelians. In 1836, he became engaged to Jenny von Westphalen, marrying her in 1843. Following the completion of his studies, he became a journalist in Cologne, writing for a radical newspaper, the Rheinische Zeitung, where he began to use Hegelian concepts of dialectical materialism to influence his ideas on socialism. Moving to Paris in 1843, he began writing for other radical newspapers, the Deutsch-Französische Jahrbücher and Vorwärts!, as well as writing a series of books, several of which were co-written with Engels. Exiled to Brussels in Belgium in 1845, he became a leading figure of the Communist League, before moving back to Cologne, where he founded his own newspaper, the Neue Rheinische Zeitung. Exiled once more, in 1849 he moved to London together with his wife Jenny and their children. In London, where the family was reduced to poverty, Marx continued writing and formulating his theories about the nature of society and how he believed it could be improved, as well as campaigning for socialism and becoming a significant figure in the International Workingmen's Association.
Marx's theories about society, economics and politics, which are collectively known as Marxism, hold that all society progresses through the dialectic of class struggle. He was heavily critical of the current socio-economic form of society, capitalism, which he called the "dictatorship of the bourgeoisie", believing it to be run by the wealthy middle and upper classes purely for their own benefit, and predicted that, like previous socioeconomic systems, it would inevitably produce internal tensions which would lead to its self-destruction and replacement by a new system, socialism. Under socialism, he argued that society would be governed by the working class in what he called the "dictatorship of the proletariat", the "workers state" or "workers' democracy". He believed that socialism would, in its turn, eventually be replaced by a stateless, classless society called pure communism. Along with believing in the inevitability of socialism and communism, Marx actively fought for the former's implementation, arguing that both social theorists and underprivileged people should carry out organised revolutionary action to topple capitalism and bring about socio-economic change.