(a)Generally speaking, in pre-capitalist societies people produced things directly for other people, not for sale on a market – in Marx’s language, they produced for use, not exchange.
(b)However, producing things for sale (or exchange) creates a new dynamic, different from societies that produce directly for use.
(c)Capitalism is very different from past modes of production.
(d)Under capitalism, nearly all of the products of human labor are commodities, that is, they are produced for sale.
(e)Every system of production has to regulate how much of people’s labor is spent producing one thing versus another, so that the society does not end up using labor on things that are useless.
(f)Marx called this “generalized commodity production”—people obtain their needs not by producing what they need, but by purchasing them on a market, and people produce what other people need and want by selling things on a market.