With the detection of relativistic broad emission lines in MCG 6-30-15 (Tanaka 1995) X-ray observations have become an important tool to test the direct environment of black holes.

XMM-Newton observations were the basis of remarkable progress in different directions in recent years. On the one side the birth and the growth of black holes could be addressed in detail. On the other side several observations allowed the study of the strong gravitational field in the vicinity of black holes.

The talk provides an overview of XMM-Newton observations of black holes: starting from the creation of stellar-mass black holes, through mass growth via accretion disks and occasional tidal disruption events, up to intermediate and supermassive black holes in the centre of active and non-active galaxies. Special attention will be given to the achieved status in the determination of the measurable quantities of black holes, i.e. mass and spin.

I suggest that stellar coalescence in mid-size protoclusters ($M {\sim} 10^{3.5}$–$10^{4.5} M_{\odot}$) is a possible scenario for the formation of ultraluminous X-ray sources (ULXs). More massive super-star-clusters are not needed, since the most likely ULX mass range is only ${\sim} 30$–$200 M_{\odot}$; in fact, they are very rarely found at or very near ULX positions. Protostellar envelopes and gas accretion favour captures and mergers in dense cores of embedded clusters. Moreover, protoclusters with masses ${\sim} 10^{3.5}$–$10^{4.5} M_{\odot}$ are likely to disperse quickly into loose OB associations, where most ULXs are found. Sufficiently high protostellar density may be achieved when clustered star formation is triggered by galaxy collisions and mergers. Low metallicity may then be necessary to ensure that a large fraction of the stellar mass ends up in a black hole. In this scenario, most ULXs are naturally explained as the extreme end of the high-mass X-ray binary population.

The IAU Symposium 230, Populations of High Energy X-ray Sources in Galaxies has been a wide-spectrum affair, with talks discussing results from the soft X-ray to the Gamma-ray range on virtually the entire universe, from our Galaxy to the high redshift regions when first galaxies emerged. I do not name any presenter in this summary, but concentrate on themes and results that I have found striking.