Relations of production (German: Produktionsverhältnisse) is a concept frequently used by Karl Marx and Friedrich Engels in their theory of historical materialism and in Das Kapital. It is first explicitly used in Marx's published book The Poverty of Philosophy, although Marx and Engels had already defined the term in The German Ideology.
By "relations of production", Marx and Engels meant the sum total of social relationships that people must enter into in order to survive, to produce, and to reproduce their means of life. As people must enter into these social relationships, i.e. because participation in them is not voluntary, the totality of these relationships constitute a relatively stable and permanent structure, the "economic structure".
The term "relations of production" is somewhat vague, for two main reasons:
Marx and Engels typically use the term to refer to the socioeconomic relationships characteristic of a specific epoch; for example: a capitalist's exclusive relationship to a capital good, and a wage worker's consequent relation to the capitalist; a feudal lord's relationship to a fief, and the serf's consequent relation to the lord; a slavemaster's relationship to their slave; etc. It is contrasted with and also affected by what Marx called the forces of production.
Here are four famous quotations showing Marx's use of the concept of relations of production:
In the social production of their existence, men inevitably enter into definite relations, which are independent of their will, namely relations of production appropriate to a given stage in the development of their material forces of production. The totality of these relations of production constitutes the economic structure of society, the real foundation, on which arises a legal and political superstructure and to which correspond definite forms of social consciousness. The mode of production of material life conditions the general process of social, political and intellectual life. It is not the consciousness of men that determines their existence, but their social existence that determines their consciousness. At a certain stage of development, the material productive forces of society come into conflict with the existing relations of production or – this merely expresses the same thing in legal terms – with the property relations within the framework of which they have operated hitherto. From forms of development of the productive forces these relations turn into their fetters. Then begins an era of social revolution. The changes in the economic foundation lead sooner or later to the transformation of the whole immense superstructure. - 1859 Preface to A Contribution to the Critique of Political Economy