Anaphora is a rhetorical device that involves the repetition of a word or phrase at the beginning of successive clauses or sentences. It is often used to create emphasis, rhythm, and emotional resonance in speech or writing. A well-known example is Martin Luther King Jr.'s "I Have a Dream" refrain in his famous speech, which reinforces his vision for equality and justice. Anaphora can enhance the persuasive power of a message by drawing the audience's attention to key themes.