Black holes are undoubtedly one of the most fascinating discoveries of modern astronomy, and their description one of the most daring intellectual feats of modern times. They have already become legendary, forming the basis of many myths, fantasies and science fiction movies. Are they really the monsters which devour light and stars; bottomless celestial pits into which all matter is sucked and crushed? Are they an observable reality, or are they just hypothetical objects from the theory.