What is the literary device that involves a contrast between what is expected and what actually occurs?

The literary device that involves a contrast between what is expected and what actually occurs is irony. This concept plays a crucial role in literature and everyday speech, as it highlights the discrepancies between appearances and reality. Irony can take many forms, such as situational irony, where the opposite of what is intended happens, or verbal irony, where someone says one thing but means another. This device not only adds depth to writing but also engages the reader by prompting them to think critically about the situations and characters within the narrative. The use of irony can evoke emotion, humor, or critical thought, making it a powerful tool for authors to convey themes and messages.