Utility 效用
（重定向自Usefulness）
In economics, utility is a measure of preferences over some set of goods and services. The concept is an important underpinning of rational choice theory in economics and game theory, because it represents satisfaction experienced by the consumer of a good. A good is something that satisfies human wants. Since one cannot directly measure benefit, satisfaction or happiness from a good or service, economists instead have devised ways of representing and measuring utility in terms of economic choices that can be measured. Economists have attempted to perfect highly abstract methods of comparing utilities by observing and calculating economic choices. In the simplest sense, economists consider utility to be revealed in people's willingness to pay different amounts for different goods.