Black Hole's are terrifying but also magical. There are e few theories about Black Holes. They can be a gate to another dimension or in a parallel universe. But let me point out another terrifying fact what if our sun became a Black Hole?
A black hole of the mass of Sun would have a size of 6 kilometers- about the size of a small city. The black hole Sun would exert the same amount of gravitational force on Earth. So Earth and other planets would continue orbiting it.
There would be no days and nights but complete darkness and freezing temperatures unless Sun continuously feeds on large amount of matter. But don't worry, Sun does not have enough mass to turn into a Black Hole. We are safe, for now!