This hook sentence is similar to a definition in that the reader may need some extra information to fully understand the essay.

Example

If you are writing an essay arguing how irony enhances the reader’s understanding of the characters in Macbeth, you could use this:

“Dramatic irony is when the audience knows something that the characters do not, situational irony happens when an expected result is warped and verbal irony is where the speaker says one thing but means another.”

Many people do not fully understand the meaning and types of irony so providing more information about this is helpful. Now the reader of your essay is better informed and can easily follow your arguments.