This book is a comprehensive yet concise overview of quantum information science, which is a rapidly developing area of interdisciplinary investigation that now plays a significant role in physics, information technology and engineering. It is a handy reference for practitioners and students covering quantum mechanics, quantum key distribution, quantum computation and quantum communication, as well as explicating foundational issues of these topics. Specific protocols for quantum coding, quantum teleportation, quantum key distribution, quantum data compression and entanglement purification are discussed, as are quantum algorithms, including the Deutsch-Jozsa, Shor and Grover algorithms. Appendices on the mathematics of quantum information science and postulates of quantum mechanics are included. The book contains more than 25 illustrations that encapsulate essential ideas and fundamental constructs of quantum information science. The bibliography contains more than 400 articles from the literature of quantum mechanics and information science. Foreword by Prof. Tommaso Toffoli.