The ultimate proofs that black holes exist have been obtained very
recently thanks to the detection of gravitational waves from their
coalescence and due to material orbiting at a distance of some
gravitational radii imaged by optical interferometry or X-ray
reverberation mapping. This book provides three comprehensive and
up-to-date reviews covering the gravitational wave breakthrough, our
understanding of accretion and feedback in supermassive black holes and
the relevance of black holes for the Universe since the Big Bang.
Neil J. Cornish presents gravitational wave emission from black hole
mergers and the physics of detection. Andrew King reviews the physics of
accretion on to supermassive black holes and their feedback on host
galaxies. Tiziana Di Matteo addresses our understanding of black hole
formation at cosmic dawn, the emergence of the first quasars, black hole
merging and structure formation. The topics covered by the 48th Saas-Fee
Course provide a broad overview of the importance of black holes in
modern astrophysics.