This book provides an up-to-date and comprehensive account of quasars and active galactic nuclei (AGN). The latest observations and theoretical models are combined in this clear, pedagogic textbook for advanced undergraduates and graduate students. Researchers will also find this wide-ranging and coherent review invaluable. Throughout, detailed derivations of important results are provided to ensure the book is self contained. And theories and models are critically compared with detailed and often puzzling observations from across the spectrum. We are led through all the key topics, including...