But here is the interesting part. If you make something smaller by squishing it, its gravity becomes much stronger. Imagine then, if you squish a star into the size of an atom how powerful its gravity would become. A black holes gravity becomes so powerful that anything including light that comes to close to it gets pulled in. The middle of a Black Hole is called a Singularity .
Singularity is simply a big word that means squashed up star.
When you get to close to the singularity you will begin to fall into it. At this point you could still escape, but you had better hurry, because as soon as you pass the Inner Event Horizon it will become impossible to get out. Think of the Earth. When you are in outer space you can float around. However if you get to close to the Earth you will be pulled in.