This document discusses key economic concepts including the economic problem, opportunity cost, and production possibility frontiers. It explains that economies have unlimited wants but scarce resources, so they must make choices about what and how to produce and who receives goods and services. Opportunity cost refers to the next best alternative given up when a choice is made. Production possibility frontiers illustrate the various combinations of two goods an economy can produce and show that increasing one requires decreasing the other due to scarce resources.