A useful item that is traded or sold for profit. Usefulness (or ‘use value’) alone does not make something a commodity. For example, an apple picked from a tree is not a commodity, whereas an apple grown for sale is. The process of transforming a useful thing into something that is traded for profit is called ‘commodification’.
Carbon trading and ecosystem services are instances of commodification. The former quantifies pollution into tradeable units (carbon credits and carbon permits), while the latter generates a whole range of new tradeable products (from water cycling to habitat provision), privatizing what were until now common goods. These can be interpreted as part of a broader trend towards commodification (and financialization), which is driven by capitalism’s need to find new assets to trade profitably.