For the last 40 years astronomers have observed sources of intense X-ray radiation from beyond our Solar System. These have been associated with remarkable objects, such as neutron stars and black holes. Current satellite observatories have enabled us to extend the studies of these objects from the Milky Way and Magellanic Clouds to individual X-ray sources in other galaxies. At the same time, imaging facilities at gamma-rays and TeV energies have improved enormously, leading to many further discoveries within our own galaxy. This Symposium presents an overview of these new developments, covering detailed studies of individual sources within the Milky Way, global descriptions of X-ray source populations in other galaxies, and less resolved relatives at high redshift. Galaxy nuclei and diffuse emission components are included, as are new discoveries at gamma-rays and TeV energies. IAU S230 is a valuable resource for astronomers and graduates working in high-energy astrophysics.