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Consider a set of alternatives facing an individual,
and over which the individual has a preference ordering.

A utility function is able to represent those preferences if it is possible
to assign a real number to each alternative,
in such a way that alternative a is assigned a number greater than
alternative b if, and only if, the individual prefers alternative a to alternative b.

In this situation an individual that selects the most preferred alternative available is
necessarily also selecting the alternative that maximizes the associated utility function.

In general economic terms, a utility function measures preferences
concerning a set of goods and services.

Often, utility is correlated with words such as happiness, satisfaction, and welfare,
and these are hard to measure mathematically.
Thus, economists utilize consumption baskets of preferences in order to
measure these abstract, non quantifiable ideas.