This handbook includes over 100 chapters, written by experts from around the world. It examines drought and all of the issues relating to drought and water scarcity, including causes, impacts, modeling, capacity building, early-warning systems, management and policy, remote sensing, risk assessment, and more. It also explains how drought can affect different sectors in different ways, for example, rural and agricultural areas as compared to urban areas. It explains the environmental aspects of drought such as contamination, and also discusses how climate change affects drought conditions, and presents modeling for better understanding drought in uncertain and changing climates.