This is a pre-publication version of a forthcoming book on quantum atom optics. It is written as a senior undergraduate to junior graduate level textbook, assuming knowledge of basic quantum mechanics, and covers the basic principles of neutral atom matter wave systems with an emphasis on quantum technology applications. The topics covered include: introduction to second quantization of many-body systems, Bose-Einstein condensation, the order parameter and Gross-Pitaevskii equation, spin dynamics of atoms, spinor Bose-Einstein condensates, atom diffraction, atomic interferometry beyond the standard limit, quantum simulation, squeezing and entanglement with atomic ensembles, quantum information with atomic ensembles. This book would suit students who wish to obtain the necessary skills for working with neutral atom many-body atomic systems, or could be used as a text for an undergraduate or graduate level course (exercises are included throughout). This is a near-final draft of the book, but inevitably errors may be present. If any errors are found, we welcome you to contact us and it will be corrected before publication. (TB: tim.byrnes[at]nyu.edu, EI: ebube[at]nyu.edu)