The quantum world is the world of the very small - the micro-world ('quantum' means the smallest component of a system or the smallest change a system can make). Q IS FOR QUANTUM is about the inner structure of everything, a quest which, like the quest for an understanding of the Universe at large, goes back to the ancient Greeks and touches all of scientific and philosophical thought since then. Historical highlights include Newton's work on particles and Maxwell's work on waves. The longer biographies in the book include Rutherford, Feynman, Crick and Watson. An extended Introduction, which sets out the present state of knowledge, is followed by the main A-Z section, and then by 'Timelines' to indicate what was discovered when.