经济学家利用效用的概念来解释人们作出选择的原因 — — 买什么、投资什么，工作多努力：每个人都试图根据自身关于世界的偏好和信念来实现效用最大化，同时也要受到收入和资源稀缺所带来的局限。
Economists use the concept of utility to explain why people make the choices they do – what to buy, where to invest, how hard to work: everyone is trying to maximize utility in accordance with one’s preferences and beliefs about the world, and within the limits posed by scarce income or resources.