Observational evidence for supermassive black holes

We discuss the current status of supermassive black hole research, as seen from a purely observational standpoint. Since the early 1990s, rapid technological advances-most notably the launch of the Hubble Space Telescope, the commissioning of the Very Long Baseline Array, and improvements in near-infrared speckle imaging techniques-have not only given us incontrovertible proof of the existence of SuperMassive Black Holes (SMBHs), but have unveiled fundamental connections between the mass of the central singularity and the global properties of the host galaxy. It is thanks to these observations that we are now, for the first time, in a position to understand the origin, evolution, and cosmic relevance of these fascinating objects.