This volume aims to provide a comprehensive overview of thin-film magnetoresistive (MR) sensors, including the theory of magnetoresistive effects, as well as the design, fabrication, properties and applications of MR sensors. It is mainly addressed to potential and actual users of these sensors, giving essential information about the performance of various kinds of sensors, including Permalloy magnetoresistors, spin-valve sensors, multiplayer sensors, colossal effect sensors, spin-dependent tunnelling sensors and magnetoimpedance sensors. It will also be of use to the specialist employing these sensors. With over 1000 references, the book aims to provide a fully referenced and up-to-date review of their theory, development and use to date. The book is divided into three independent parts. Part One is concerned with the most widely used sensors - anisotropic magnetoresistive sensors (AMR). The second part is devoted to new giant magnetoresistive (GMR) sensors and those still in development, whilst the third part describes the applications of MR sensors, especially in data-storage systems, industrial measurements and non-destructive material-testing systems. Professor Tumanski has been active for many years in industrial and magnetic measurements and presents here his results and experience in the design and applications of MR sensors, including the results in the application of MR sensors in magnetic field analysis and materials testing. Also described in detail is Magnetovision, a measuring system developed by the author, which enables the presentation of magnetic fields in the form of colour maps.