Personification, metaphors and similes are examples of figurative language. They define or describe a person, place or thing by comparing it to another. Idioms and alliteration are other examples of figurative language.
Personification gives human qualities to nonhuman things. Authors use this device in fables and children's books, but it also appears in myths and legends. Common examples are "Justice is blind" and "The city never sleeps." Famous books that make use of this device are "Animal Farm" by George Orwell and the graphic novel "Maus" by Art Spiegelman.
Similes are a type of rhetorical analogy that compare two things by using "like" or "as." Writers use this device to make the alien more approachable and the common more interesting. Popular similes in speech include "a heart as cold as ice," "sweating like a pig" and "sleeping like a log." Langston Hughes' poem "Harlem" uses similes to compare a dream deferred to rotten meat, a sugary sweet and a festering sore.
Metaphors are stronger and more direct than similes. A metaphor states that one thing is another thing, and it comes from the Greek "metaphorá," which means "to carry over." Common examples are "Don't put all your eggs in one basket" and "It was raining cats and dogs." Famous examples are Allen Ginsberg's "Howl" and William Shakespeare's "All the World's a Stage" monologue from "As You Like It."