Black holes: from stars to galaxies
  While until recently they were often considered as exotic objects of dubious existence, in the last decades there have been overwhelming observational evidences for the presence of stellar mass black holes in binary systems, supermassive black holes at the centers of galaxies, and possibly, intermediate-mass black holes observed as ultraluminous X-ray sources in nearby galaxies. Black holes are now widely accepted as real physical entities that play an important role in several areas of modern astrophysics.   Here I review the concluding remarks of the IAU Sympposium No 238 on Black Holes, with particular emphasis on the topical questions in this area of research. 
I. F. Mirabel