Queueing Theory deals with systems where there is contention for resources, but the demands are only known probabilistically. This book can be considered to be a monograph or a textbook, and thus is aimed at two audiences: those who already know Queueing Theory but would like to know more of the Linear Algebraic Approach; and as a rst course for students who don't already have a strong background in probability, and feel more comfortable with algebraic arguments. Also, the equations are well suited to easy computation. In fact, there is much discussion on how various properties can be easily computed in any language that has automatic matrix operations (e.g., MATLAB). To help with physical insight, there are over 80 gures, numerous examples and exercises distributed throughout the book. There are, perhaps 50 books on QT that are available today, and most practitioners have several of them on their shelves. This book would be a good addition, as well as a good supplement to another text. This second edition has been updated throughout including a new chapter on Semi Markov Processes and new material on matrix representations of distributions and Power-tailed distribution. Lester Lipsky is a Professor in the Department of Computer Science and Engineering at the University of Connecticut.