John Hinckley Jr. is a man who did a very bad thing a long time ago. He tried to hurt the President of the United States by shooting him. This was a very bad thing to do and it hurt a lot of people. Hinckley Jr. was caught and put in jail for a long time.
But after a while, he was able to leave jail and go to a special place where he has to follow very strict rules. This place is called a mental hospital. A mental hospital is like a hospital for a person's brain because sometimes people's brains don't work the way they should. Hinckley Jr. stays there because he needs a lot of help and he has to follow rules to make sure he doesn't do anything bad again.