This book is an outgrowth of a course given by the author for people in industry, government, and universities wishing to understand the implica­ tions of emerging optical fiber technology, and how this technology can be applied to their specific information transport and sensing system needs. The course, in turn, is an outgrowth of 15 exciting years during which the author participated in the research and development, as well as in the application, of fiber technology. The aim of this book is to provide the reader with a working knowledge of the components and subsystems which make up fiber systems and of a wide variety of implemented and proposed applications for fiber technology. The book is directed primarily at those who would be users, as opposed to developers, of the technology. The first half of this book is an overview of components and subsys­ tems including fibers, connectors, cables, sources, detectors, receivers, transmitters, and miscellaneous components. The goal is to familiarize the reader with the properties of these components and subsystems to the extent necessary to understand their potential applications and limitations.