With the advent of portable and small-sized computing systems, and with the new trends towards embedded and systems-on-a-chip computing, power management has emerged as a focal point in many research projects and commercial systems. In these systems, better management of power translates into longer battery life or into smaller batteries, which in turns implies smaller and lighter devices. Power management is also crucial in autonomous systems such as satellites and unmanned vehicles and planes. In such systems, better power management translates to longer missions or to smaller and lighter power generation systems, which makes room for other instrumentations to be added to the system. This book covers a wide spectrum of power optimization and management techniques that spreads from circuit level optimization to application level power management. The spectrum includes power optimization and management at the microarchitecture level, the compiler level and the operating system level. The book also describes a number of methods for modelling and measuring power consumption in computer systems and for evaluating the effectiveness of power management techniques.