Question: What is a black hole and how are they formed?

Janis Aleksans answered on 13 Nov 2019:

Black hole is an object which has gravity so strong that even light can’t escape it, that is why it appears to be black. The biggest ones have gravity so strong that they hold entire galaxies around them. There is a black hole in the center of every galaxy including ours, The Milky Way! Black holes form as a very last stage of a star’s life, when it pretty much implodes.