Understanding economics is critical to understanding the history of humanity, from hunter-gatherers to today. Economics is the study of decision-making and how humans make decisions. Without understanding economics we cannot understand the trajectory of history over the last 10,000 years. This chapter reviews basic economic principles, and how economies have evolved through time. It discusses the economic principles of Adam Smith and Karl Marx, the differences between a market economy and a command economy, and the political and historical implications of the clash between those two models.