A metaphor is a figure of speech that replaces something literal with something symbolic. The metaphorical element may be something unrelated to the subject being discussed, but it adds meaning through the comparison that it implies. For example, you might say, "Jane and Bob's relationship has been a long, hard journey." Of course, the relationship is not literally a journey, but the metaphor communicates something meaningful about it. Metaphors are easy to use and can bring your sentences to life.
When revising your writing, try using metaphor to add color and meaning to your sentences. For example, you might have written, "Students today are eager to incorporate the latest computer technology into their studies." To transform the sentence, add a metaphor, like this: "Students have voracious appetites for technology and will gobble up any educational programs that come their way." The metaphor has enhanced the tone and meaning of the sentence, and it's a lot more fun to read.