A metaphor is a comparison between two things that replaces the word or name for one object with that of another. Unlike a simile that uses “like” or “as” (you shine like the sun!), a metaphor does not use these two words (a famous line from Romeo and Juliet has Romeo proclaiming “Juliet is the sun”). Metaphors are commonly used throughout all types of literature, but rarely to the extent that they are used in poetry.