Theoretically they can be as large
as a small star or as large as a galaxy
stellar black holes were stars (these are large)primordial black holes were pieces of the big bang (these are microscopic)
Black holes are the result of the gravitational collapse of a large star.
Black holes. They can be so large that they can suck up universes at a time
Most black holes were once the cores of very large stars that collapsed.
The most massive stars will die as black holes.
Black holes are the result of a large star that has collapsed.
Not all galaxies have black holes in their centers, but many large galaxies, including our own Milky Way, are believed to have supermassive black holes at their centers.
Usually at the center of a galaxy or where a large star has exploded.
'Black holes' and neutron stars.
Black holes are not made up of dark matter. Dark matter is a mysterious substance that makes up a large portion of the universe's mass, but black holes are formed from the collapse of massive stars.
The relevant magnitude is mainly the black holes' mass. Since black holes are the result of collapsing stars, yes, there are black holes with the mass of a star.The diameter is usually taken as the diameter of the event horizon. This diameter is directly proportional to the mass; a supermassive black hole such as Sag A* has a diameter comparable to that of a large star.
Most black holes are stellar mass black holes with masses comparable to those of large stars as they form from the collapse of massive stars. Scientists know of the existence of supermassive black holes that are millions to billions of times the mass of our sun and can be found in the centers of most galaxies. Scientists still do not know how these black holes become so massive.