Black holes are celestial objects which are so dense, that not even light can escape they intense gravitational pull. Their gravity is not sufficient to overpower the atomic and nuclear forces of their interiors, which resist compression. But in more massive objects, gravity ultimately wins. This phenomenon occurs when a dying stars runs out of fuel and collapses under the weight of their own gravity. According to scientists, there might be three types of black holes : stellar, supermassive, and miniature – depending on their mass. Astronomers can measure the mass of black holes by studying the material that orbits around them.
Stellar black holes form when a massive star collapses.
Supermassive black holes, which can have a mass equivalent to billions of suns, likely exist in the centers of most galaxies, including our own galaxy, the Milky Way.
Miniature black holes might have formed in the early universe. But astronomers do not have any evidence of their existence. Miniature black holes have event horizons as small as the width of an atomic particle and might have been created during the Big Bang, the moment the universe was created.
Black holes can spin around an axis, although the rotation speed cannot exceed some limit. Astronomers think that many black hole in the Universe probably do spin, because the objects from which form (stars for example) generally rotate as well. Observations are starting to shed some light on this issue, but no consensus has so far emerged. They could also be electrically charged. However, they would then rapidly neutralize that charge by attracting and swallowing material of opposite polarity. So astronomers believe that all black holes in the Universe are uncharged.