This document outlines the key principles of economics according to Gregory Mankiw's textbook. It discusses the basic questions addressed by economics and identifies four main categories of economic principles: how people make decisions, how people interact, how the overall economy works, and the study of scarcity. Ten specific principles of economics are defined within these categories, including that people face tradeoffs, rational people think at the margin, and markets are generally good for organizing economic activity but governments can sometimes improve outcomes. Examples are provided to illustrate each principle.