Joker is a good movie but not easy to understand, even the audience after stepping out of the theater still can not distinguish exactly what is happening and what events are imagined by Arthur. . However, the audience will understand the bitterness that Arthur suffered before becoming a Joker. Why does everyone ask you what is funny to laugh about, and no one asks why you laugh non-stop? Why do people make a mentally ill person act like a normal person? Why does no one use Arthur’s true heart to become Arthur’s friend? …. So many questions are raised, so many issues are mentioned that make the film bold and dark atmosphere makes the audience fake walking out of the theater but still haunted by what Joker brings.