1. Irony
the expression of one's meaning by using language that normally signifies the opposite

2. Verbal Irony
Verbal irony is the use of words to mean something different from what a person actually says.
Example: “Thanks for the ticket officer you just made my day!”

3. Dramatic Irony
Dramatic Irony is when the audience is aware of something that the characters in the story are not aware of.
Example: When Romeo kills himself to be with Juliet because he believes her to be dead. Yet the audience knows she is just asleep.

4. Situational Irony
Situational Irony is when the exact opposite of what is meant or expected to happen, happens
Example: In Greek mythology Cronus eats his children so none of them can over throw him. When he is tricked by a stone, it is his very son Zeus who over throws him.
Note: there is a difference between bad luck and situational irony.