Figures of speech are forms of expression that convey meaning or heighten effect by comparing or identifying one thing with another that has familiar meaning. Some common figures of speech are similes, which use like or as to compare two unlike objects; metaphors, which make an indirect comparison; and personification, which gives human traits to nonhuman things. Other figures include irony, oxymoron, hyperbole, paradox, and metonymy. Rhetorical devices also convey meaning through sound, such as onomatopoeia, alliteration, rhyme, and anaphora.