This book contributes as a rich source of information on the synthesis, main properties, toxicity and applications of Deep Eutectic Solvents (DESs). It covers the viable and sustainable use of these special solvents that due to the versatility of the preparation can be tuned for specific applications. Both hydrophilic and hydrophobic DESs are covered over the chapters. The book covers, in addition to the fundamentals of DESs, their use in extraction processes, in the pre-treatment of biomass, as solvents for catalytic processes and in processes for carbon dioxide capture, among others. The purpose of the book is it can reach a wide audience, so it can serve both as a reference for experienced professionals and to students interested in the field. In this sense, the book contributes to the state of the art in the application of DESs and addresses the challenges that must be faced for the industrial application of these special solvents.