Astrophysical evidence for the existence of black holes

Following a short account of the history of the idea of black holes, we\npresent a review of the current status of the search for observational evidence\nof their existence aimed at an audience of relativists rather than astronomers\nor astrophysicists. We focus on two different regimes: that of stellar-mass\nblack holes and that of black holes with the masses of galactic nuclei.\n