From the beginning of this century, there has been a dramatic increase in interest in the study of surface plasmon polaritons-based metallic subwavelength structures and learning. This is a refreshing concise book on issues and considerations in designing, nanofabrication and characterization of subwavelength plasmonic structures as well as their applications in imaging, superfocusing, semiconductor lasers, data storage, optical communications, biosensing, and immunoassays. The book can serve as a textbook for education and training as well as a reference book that aids research and development in those areas integrating light, photonics, nanotechnology, semiconductors, chemistry, and biology. Another aim of the book is to stimulate the interest of researchers, engineers, and businessmen to foster collaboration through multidisciplinary programs in this frontier science, leading to development and transition of the resulting technology. Both basic and applied aspects are presented in this book. Many illustrative worked-out examples and instructive exercises are given, which should prove to be particularly useful.