This book draws together the essential elements of classical electrodynamics, surface wave physics, plasmonic materials, and circuit theory of electrical engineering to provide insight into the essential physics of nanoscale light-matter interaction and to provide design methodology for practical nanoscale plasmonic devices. The structure of the book is designed around five principal chapters, but many of the chapters have extensive "complements" that either treatimportant digressions from the main body or penetrate deeper into some fundamental issue. Furthermore, at the end of the book are several appendices to provide readers with a convenient reference for frequently-occurring special functions and explanations of the analytical tools, such as vectorcalculus and phasors, needed to express important results in electromagnetics and waveguide theory.