This decade has seen a large number of high-energy space missions, which, alongside ground-based optical and radio telescopes, have enabled the detailed study of accreting compact objects. IAU S290 addresses the state-of-the-art research on accretion in astrophysical objects and systems ranging in scale from active galactic nuclei down to stellar black holes, neutron stars and white dwarfs, by bringing together scientists from each of these fields. It focuses on understanding the common physics of slow and relativistic outflows in these objects and features reviews on modelling, observations and instrumentation. Specific topics covered in this volume include: the physics of accreting systems, the magnetic environment around compact objects, large scale properties of accretion, the accretion-ejection connection, jets and outflows, and instrumentation. The fundamentals of accretion and its applications are reviewed in several of the papers, making this a useful reference guide for researchers and graduate students in astrophysics.