  Relativistic outflows are a common phenomenon in accreting black holes.
Despite the enormous differences in scale, stellar-mass black holes in X-ray
binaries and collapsars, and super-massive black holes at the dynamic centre of
galaxies are sources of jets with analogous physical properties. Synergism
between the research on microquasars, gamma-ray bursts, and Active Galactic
Nuclei should help to gain insight into the physics of relativistic jets seen
everywhere in the Universe.
