The basic economic problem is that human wants are unlimited while resources are scarce. This means that societies must make choices about how to allocate scarce resources between alternative uses to best satisfy people's needs and wants. The opportunity cost of a choice is the value of the best alternative forgone, or what is given up by making that choice. Production possibility curves illustrate this problem by showing the tradeoffs involved - producing more of one good requires producing less of another since resources are limited.