What literary device employs extreme exaggeration for effect?

Hyperbole is a literary device that uses extreme exaggeration to create emphasis or a dramatic effect. It is not meant to be taken literally; rather, it serves to highlight a particular feeling, situation, or quality by stretching the truth far beyond what is reasonable or believable. For example, saying "I'm so hungry I could eat a horse" dramatically emphasizes one's hunger without intending it to be a literal statement.

In contrast, the other options serve different purposes: a simile compares two different things using "like" or "as," a metaphor makes a direct comparison between two unlike things without using "like" or "as," and personification gives human qualities to non-human entities. Each of these devices has its own function in writing and does not exhibit the extreme exaggeration characteristic of hyperbole.