This document provides an introduction to microeconomics. It defines economics as the study of how scarce resources are used to meet unlimited human wants. It discusses different definitions of economics provided by economists over time, focusing on wealth, welfare, scarcity, and growth. It also explains the central problems that all economies face regarding allocating scarce resources efficiently among competing uses. Specifically, economies must determine what and how much to produce, how to produce it, and who receives the goods and services. The document outlines different types of economic systems - market, command, and mixed - that societies use to address these allocation problems. Finally, it introduces the production possibility frontier as a way to visualize scarcity and tradeoffs in resource allocation.