Black holes are considered amongst the most mysterious objects in the universe. Part of their intrigue arises from the fact that they are actually among the simplest solutions to Einstein's field equations of general relativity. In fact, black holes can be fully characterized by only three physical quantities: their mass, spin and charge. Since they have no additional "hairy" attributes to distinguish them, black holes are said to have "no hair"—Black holes of the same mass, spin, and charge are exactly identical to each other.