Karl Marx and Friedrich Engels developed Marxist theory, which views society and history through the lens of class struggle and economic determinism. Marx argued that under capitalism, the bourgeoisie exploits the proletariat by appropriating the surplus value of their labor, and that this contradiction will ultimately lead to revolution and the establishment of a communist society without social classes. Marxism analyzes societies using concepts like historical materialism, dialectical materialism, the base-superstructure model, and the forces and relations of production.