This comprehensive handbook on the rapidly advancing field presents the foundations of quantum information, taking into account the current state of research and development, and the emerging and already realized applications in quantum technology. It thus covers all current concepts in quantum computing, both theoretical and experimental, before moving on to the latest implementations of quantum computing and communication protocols. It is a must-have for experimental and theoretical physicists in academia and industry as well as for materials scientists, engineers and computer scientists who work in the field of quantum information. The handbook is the substantially enlarged successor to "Lectures on Quantum Information" and incorporates important recent developments such as quantum metrology, quantum correlations beyond entanglement, and advances in quantum computing with solid state devices.