Black holes are a source of wide fascination. In this Very Short Introduction, Katherine Blundell addresses a variety of questions, including what a black hole actually is, how they are characterised and discovered, to what happens if you get too close to one. Explaining how black holes form and grow across cosmic time, as well as how many there are in the Universe, she also considers how black holes interact with matter - by stealing material that belongs to other stars, and how black holes give rise to quasars and other spectacular, yet exotic phenomena in outer space.Black holes are a source of wide fascination. In this Very Short Introduction, Katherine Blundell addresses a variety of questions, including what a black hole actually is, how they are characterised and discovered, to what happens if you get too close to one. Explaining how black holes form and grow across cosmic time, as well as how many there are in the Universe, she also considers how black holes interact with matter - by stealing material that belongs to other stars, and how black holes give rise to quasars and other spectacular, yet exotic phenomena in outer space.