Magnetic field sensors have made significant advances over the past decade, and have found commercial importance in ubiquitous systems with navigation needs such as mobile phones - every mobile phone now contains a vectorial magnetic field sensor. This book provides a comprehensive introduction to the underlying theory of magnetic-field microsensors, their construction, and current and future applications. Written by leading experts in the development of these sensors, this book is essential reading for academics and advanced students working in sensor design and application.