The organisation of society depends on means of production. The means of production are all things required to produce material goods, such as land, natural resources, and technology but not human labour. The relations of production are the social relationships people enter into as they acquire and use the means of production. Together, these compose the mode of production and Marx distinguished historical eras in terms of modes of production. Marx differentiated between base and superstructure, where the base (or substructure) is the economic system and superstructure is the cultural and political system. Marx regarded this mismatch between economic base and social superstructure as a major source of social disruption and conflict.