Evidence for Black Holes in the Universe

There is excellent evidence that black holes exist throughout the Universe. Black holes as heavy as the Sun are scattered throughout galaxies like our own, while black holes with masses millions or even billions of times heavier than the Sun are situated in the centers of galaxies. In this talk, I will review the nature of black holes, particularly how they form, and describe the evidence that leads astronomers to claim that they are ubiquitous in the Universe.