This book surveys all aspects of the Josephson effect—from the underlying physical theory to actual and proposed engineering applications. Both ends of this spectrum are interesting. The physical theory is novel and important for many macroscopic quantum effects, which have a rich and yet untapped potential for technical development. We attempt here to present more than a survey and less than an exhaustive exposition of this wide field. Rather than to cover everything, we have tried to uncover those aspects of theory, fabrication technology, and device application that will be of lasting value.