A black hole is a region of space from which nothing, not even light, can escape. In happens when one or more stars instead of exploding, implode. They collapse into themselves and become so dense, and so heavy that their combined gravity pulls everything around it to itself. Even light gets pulled in that’s why it becomes like a black hole. Black holes are mysterious; we can’t really tell what’s inside of them. Our super telescopes detect them to be billions of light years away. That’s a very long distance when you consider a light year to be the distance that light can travel in a year’s time. The study of black holes helps scientists to learn more about how early galaxies were created. It teaches them the behavior of gravity on the objects around it and how a black hole could be making a difference in the way new galaxies and stars are shaped. Black holes are seen only because they are surrounded by stars and planets that are far enough from it that do not get pulled in but stay around therefore when looked at from far with a telescope, we can detect galaxies of light with a surprise black spot (hole) in the middle of it. So, the next time you come close to a black hole, be very careful because if you get closer than you should, you will get pulled and will never be seen again :-)

want to learn more? http://amazing-space.stsci.edu/resources/explorations/blackholes/teacher/sciencebackground.html