A simile compares one thing to another, using the words "like" or "as." An example of a simile is: "Her hair shimmered like gold."
A metaphor is a stronger comparison than a simile as it does not use "like" or "as." Use of metaphor implies that the things being compared are equal, for instance: "Her hair was gold."
In metonymy, the name of a thing is replaced by something associated or attributed to it. Examples include referring to a monarch as the crown or to theater as the stage.
Hyperbole is an extreme exaggeration used for emphasis and not meant to be believed. Examples of hyperbole include "I could eat a horse" and "older than time."
Alliteration is figurative language in which consonants are repeated, usually at the beginning of words.