Dramatic irony, situational irony and verbal irony are literature's three main types of irony. The basis of irony is that there is a difference between what is expected and what is real. Overall, irony deals with the unexpected. The purpose of irony can be to make one think, to make one laugh, or simply to shock. Irony also can serve to add suspense and intrigue to story plots.
Situational irony, one of the easier-to-recognize types of irony, involves the actual outcome being much different from the outcome that was expected. If a character in a novel is a bad person who is robbing a bank and putting lots of other people in danger, then it might be unexpected for him to get away with all the money he wants without being caught. A nice, warm story about a child receiving a pet bird for her birthday might contain situational irony if it turned out that, unknown to her parents, she is allergic to birds and quickly becomes ill, necessitating the removal of her new pet. Situational irony often helps to keep readers interested and guessing about what might happen next, because it is not easy to predict.
Another of the main types of irony, verbal irony happens when a character says one thing but means something totally different. Take two characters who are colleagues working in an office and talking about their boss, Dr. Young, for example. One of them might say, “There is nothing I’d like more than to see Dr. Young right now.” While the character saying this might mean he would love to see their boss so he can punch the man, whom he despises, his colleague might think he means he thinks highly of their boss and would love to see him. Verbal irony sometimes is easy to pick out in literature; other times it is more subtle and requires some thinking.
Dramatic irony, also one of the main types of irony, occurs in literature when one or more characters lack a vital piece of information that has been provided to the audience. In a play, for example, if a couple has decided that they are breaking up instead of getting married but their unknowing families are busily preparing for their wedding, then this is considered dramatic irony. With dramatic irony, the audience always knows more than the individual characters in a story.