John Gribbin has collected the answer to everything you need to know about the quantum world - the place where most of the greatest scientific advances of the twentieth century have been made. This reference begins with a thorough introduction setting out the current state of knowledge in particle physics. Gribbin blends articles on the structure of particles and their interactions, accounts of the theoretical breakthroughs in quantum mechanics and their practical applications, and entertaining biographies of the scientists who have blazed the trail of discovery. In a special section, "Timelines," key dates in our quest to understand the quantum world are mapped out alongside landmarks in world history and the history of science. Q is for Quantum is an essential companion for anyone interested in particle physics.