This chapter introduces the idea of complexity and illustrates it in several ways. It begins with a suggestive example of what may be a real world example of the famous ‘butterfly effect’ in which small changes in China caused a political upheaval in the US which then reverberated on China. The chapter then summarizes some essential concepts which it illustrates using the earlier narrative of the interactions of policy changes and politics in the US and China. Next it explains how politics and politicians naturally simplify complexity. The chapter continues by explaining the difference between government and governance and their roles in policymaking for complex social systems. Two versions of football illustrate the difference in organization between orderly government and complex governance. The chapter ends with an outline of the book and a summary of each chapter.