1. Introduction

Semi-arid and arid regions worldwide regularly confront drought. Some of the potentially significant and far reaching consequences of drought include impacts on: poverty rates, health, ecosystem services, land sustainability, and economic development. Unfortunately, recent climate change models predict that over the next 40 years, semi-arid and arid regions worldwide will experience an increase in the severity and intensity of drought as these regions encounter more aridity and less precipitation. The objective of this chapter is to introduce the issues that drought present in semi-arid and arid environments. We summarize our understanding of drought and its significant costs, as well as experience from managing and/or responding to drought from scientists, water managers, and policy makers across five countries—Australia, the United States, Mexico, South Africa, and Spain. The chapter provides a synopsis of arguments detailed in later chapters that explain how better understanding of drought indicators and experiences in management can reduce the cost of mitigation and adaptation.