One of the best ways to understand the nature of something is to compare it against something else whose attributes are known. Authors frequently use comparisons in their writing to help to express what they mean in terms with which the reader can relate. That is the point of writing after all -- to communicate ideas clearly between the author and the audience. One of the most used types of literary comparisons is the metaphor.

A metaphor is a phrase of words that makes a comparison between two unlike objects without using the words "like" and/or "as." Like its cousin, the simile, the metaphor is used to provide the reader with information about a person or an object by comparing it to something with which the reader is familiar. For example, the metaphor, "the house was an oven when the air conditioner broke in July," gives the reader a greater understanding about the temperature inside the house by comparing it to an oven, which is known to be hot. The reader makes an implied connection between the house and the oven to come to the conclusion that the house is indeed hot.

Like similes, metaphors can be either implicit or explicit in nature. An implicit metaphor is a metaphor in which the characteristic being compared between two objects is not stated and left up to the reader to imply the meaning from the context of the sentence. The previous example is an example of an implicit metaphor in which the reader has to make the inference that the house is hot. For an implied metaphor, a reader has to draw upon their own experiences to make the connection. A metaphor is explicit if the characteristic being compared is stated. For example, if the sentence were to be changed to say, "The house was so hot that it was an oven when the air conditioner broke in July," it would be an example of an explicit metaphor, because the characteristic, hot, is stated.

When constructing metaphors it is important to draw on personal experience to create interesting and meaningful comparisons. However, writers should not stray too far or make a metaphor too abstract so that the average reader has a hard time grasping the point of the comparison. Metaphors should be original, so that they are not cliché, but also concrete enough that readers do not have to be intimately familiar with the details of an author's life in order to understand the meaning of the sentence or phrase.

Metaphors like all figures of speech add interest and imagery to a piece of writing. Metaphors can also increase the emotional content and connections between the words and the reader, which can provide a richer and more fulfilling experience.