Given the immense progress achieved in elucidating protein-protein complex structures and in the field of protein interaction modeling, there is great demand for a book that gives interested researchers/students a comprehensive overview of the field. This book does just that. It focuses on what can be learned about protein-protein interactions from the analysis of protein-protein complex structures and interfaces. What are the driving forces for protein-protein association? How can we extract the mechanism of specific recognition from studying protein-protein interfaces? How can this knowledge be used to predict and design protein-protein interactions (interaction regions and complex structures)? How can we influence protein-protein interactions by mutagenesis and small-molecule drugs or peptide mimetics?The book consists of 13 review chapters, written by experts, on the characterization of protein-protein interfaces, structure determination of protein complexes, theory of protein-protein binding, prediction of interfaces and prediction of protein-protein complex structures. It serves as a bridge between analyzing protein-protein complexes and the prediction and design of interactions.