A pun is a play on words by using them in a different way. This literary device allows the writer to use a word in different forms by implying a different meaning.
A pun is used more often in a humorous way when a word is used to mean multiple things. This play on words allows the listener to feel funny yet still also gives a sense of correctness in what has been said.
For example, when someone says <em>"a happy life depends on a liver"</em>. So, liver here may mean the human liver, the organ, or simply someone who lives for every moment.
