This volume presents for the first time a comprehensive description of magnetic sensors with special emphasis placed upon technical and scientific fundamentals. It provides important definitions and a unique overview of concepts, and the nature and principles of magnetic fields. General questions concerning all types of magnetic sensors, such as those pertaining to material, noise, etc. are treated. Each chapter contains physical and mathematical fundamentals and applied technical concepts. In addition, each chapter presents an outline of the most important applications, measurement ranges and accuracy of sensing etc. This volume is an indispensable reference work and text book for both specialists and newcomers, researcher and developers.