Diction refers to the choice of words and style of expression used by a writer or speaker. It plays a crucial role in conveying tone, mood, and meaning. Different types of diction, such as formal, informal, colloquial, or slang, can significantly affect how a message is perceived by the audience. In literature, diction helps to establish character voice and setting. For example, the use of formal diction in a Shakespearean play creates a different atmosphere than the informal diction found in contemporary novels. Understanding diction allows readers to appreciate the nuances of language and the intentions behind a writer's choices.