Accretion onto compact objects: from disks to spherically symmetric modes

I will discuss different regimes of accretion onto a compact object with particular emphasis on the comparison of the geometry of the accretion flow across the range of masses, mass accretion rates and compact object types. Predictions of theoretical models will be confronted with observations of compact X-ray sources in the Milky Way and beyond. Observations of X-ray binaries in our Galaxy give us a possibility to investigate individual systems in great detail, providing us with the wealth of data for comparison and tuning of theoretical models. On the other hand, observations of compact sources in external galaxies give us a unique chance to explore accretion at its extremities. To this end, I will discuss ultra-luminous X-ray sources and their possible role in exploring non-standard accretion regimes which do not realize in binary systems more commonly observed in our Galaxy.