First Supermassive Black Holes and Structure Formation -- Observations of Supermassive Black Holes at Higher Redshift -- Observations of Super Massive Black Holes in the Local Universe -- The Case of Sagittarius A* -- Interaction of Supermassive Black Holes with Their Environment -- Physics of Accretion Discs Around Supermassive Black Holes -- Black Hole–Black Hole Mergers and Gravitational Waves -- Jeds, Outflows and QSO Feedback -- The Cosmological Evolution of Active Galactic Nuclei and the X-Ray Background.Supermassive black holes are now believed to play an important role in the evolution of the Universe. Every respectable galaxy hosts in its center a black hole that appears to regulate the growth of the galaxy itself. In this book, leading experts in the field review the most recent theoretical and observational results on the following topics: * formation and growth of the first black holes in the Universe and their role in the formation and evolution of galaxies * the physics of black-hole accretion and the production of relativistic jets * binary black-hole mergers and gravitational radiation. Theoretical work is supplemented by the most recent exciting results from space and ground based observatories. This volume is useful research and reference tool for the entire astrophysical community.