This is the second edition of a 1991 book, describing the physics and technology of semiconductor electron devices exploiting the Hall effect. These are magnetic field sensitive devices such as Hall elements, magnetoresistors and magnetotransistors. Hall effect devices are commonly used as magnetic field sensors and as means for characterizing semiconductors. The book provides a clear analysis of the relationship between the basic physical phenomena in solids, the appropriate materials characteristics, and the characteristics of Hall effect devices. Particular emphasis is placed on important developments inspired and made possible by advances in microelectronics. A special feature of the book is its broad scope. A reader will find in the book physical basics of Hall effect devices, clear guidelines for the design of practical Hall elements, detailed description of the best interface electronic circuits, examples of the most successful industrial products in the field, and examples of their applications.