In economics, the marginal utility of a goo or service is the utility of the specific use to which an economically rational agent would put a given increase in that good or service, or of the specific use that would be abandoned in response to a given decrease. In other words, marginal utility is the utility of the marginal use — the least urgent use of the good or service, from the best feasible combination of actions in which its use is included. Under the mainstream assumptions, the marginal utility of a good or service is the posited quantified change in utility obtained by using one more or one less unit of that good or service.