The object of this book is to provide a comprehensive treatment of the principal issues in modern instrumentation, but without attempting an encyclopedic reference. It thus discusses the basic theory and physical principles underlying the operation of the various sensors as well as the practical aspects of their operation and their incorporation into larger systems. The intent is to cover the most important topics in electronics, sensors, measurements, and acquisition systems, always keeping in mind the needs of practicing scientists and engineers. The presentation focuses on systems controlled by desktop personal computers running a high-level program and operating through internal cards or an external bus connected to instruments, rather than the specialized microprocessors discussed in older texts. The book will thus be useful to students in a wide variety of experimental sciences and engineering disciplines, including physics, chemistry, mechanical, nuclear, and electrical engineering, experimental psychology, biology, and geophysics.