A metaphor is a figure of speech in which one word or phrase stands in for another, even if the words do not have similar definitions. Comparisons between the terms normally have implicit or hidden meanings. The words may connote common attributes between two or more things.
The simplest metaphors directly compare one object to another, such as the phrase "God is love." Although neither of the abstract concepts of "God" and "love" have the same literal definitions, a metaphor directly compares the two nouns.
Another simple metaphor includes "The man is a black sheep." A human can never truly become a black sheep with regards to biology or genetics, but in literary terms the "black sheep" connotes someone who is different from everyone else in a family or social group since sheep are normally white.
Famous literary examples of metaphors come from many classic poets. William Shakespeare's "Sonnet 18" says, "Shall I compare thee to a summer's day?" The entire poem serves as an extended metaphor that illustrates someone's love interest as several abstract concepts.
A metaphor differs from a simile in that a simile uses the words "like" or "as" to directly compare two unlike concepts. For instance, "The two men are as alike as two peas in a pod" represents a way to visualize two people with a lot in common since peas in a pod are close to one another and appear very much the same.