What is a black hole.... It is put into a very small space. And It is a very heavy masses. In other words, it shows a very high density. So strong gravity.
Black holes attract the stars around. Then, it swallows. This is the principle of the generation.
he black hole appeared in many movies. Wormholes and white holes also appeared a lot.
In fact, the black hole pulls even light. Therefore, we can not see a black hole. But you can see the surrounding. It is a scene in the movie. Generally, the black hole is at the center of the galaxy. However, there may be even around us.