Access to clean water and energy are critical to economic growth and sustainable development. Providing water and energy services has important environmental impacts. Understanding the inextricable linkages among water, energy, and environment - the water-energy-environment nexus - will be a priority for all levels of government in the decades ahead as they develop and implement policies to enhance human welfare. We are also experiencing the beginning of an energy revolution in these early years of the 21st Century. Understanding the nature of this revolution is important, and this book provides an introduction to and explanation of this revolution. Specific topics to be discussed, in addition to explaining the nexus, include the global contexts for water and energy issues, associated environmental impacts, traditional and emerging energy options (fossil fuels, nuclear power, renewable energies), new approaches to providing clean water, the emerging role of energy storage, and policy issues associated with water, energy, and environment, as well as recommendations. There are a number of books on pieces of the nexus, most at a technical level. The purpose of this book is to explain the nexus and each of its components in a university-level, highly-readable 'primer' for those entering the water and energy fields. It will also serve as an introduction to these topics for a global, multidisciplinary audience that includes academic scholars in related technical and non-technical fields, government officials at national, state, and local levels, economists and others in the financial/investment communities, and those in the development community responsible for planning and delivering water and energy services to undeserved populations.