This book is the first to offer a general discussion on the cupling methods for nonliner problems, and provides all material necessary for an introductory course on the subject. Readers are assumed to have only a basic knowledge of applied functional analysis and partial differential equations at graduate level. This book can be used as an advanced graduate text as well as a reference for specialists working in the areas of partial differential equations, boundary integral equations and scientific computing. This book will be of particular interest to students and researchers in applied mathematics, numerical analysis and partial differential equations.