Black holes form when the center of a very big star collapses on its self itself. Blacks holes don’t move arond space. Black holes are usealy 10 to 24 times bigger than the sun. The largest balck hole is in the milkyway. If anthing gets to close it a black hole it is there forever . Around black holes you might find dust and thick gas. When a star gets to close to a black hole it will get ripped apart. Astronomers estimate there are anywhere from 10 million to a billion black holes in space.
A black hole does not have a surface, like a planet or star. If a human was to fall into a black hole they would be stretched untill they snap. A black hole can pull in things that are 3 times bigger than the its self. Black holes can even pull in light and light is not a object in itsself.