This document introduces concepts around scarcity, choice, opportunity costs and trade. It discusses how scarcity requires individuals and societies to make choices about allocating resources. Trade allows for specialization and is mutually beneficial for parties involved. The production possibilities curve is introduced as a way to illustrate scarcity and opportunity costs at the society level. Shifts in the PPC can occur from economic growth as resources and technology change. Different economic systems like markets and command economies are also covered.