A pun is a form of wordplay that uses homonym or near-homonyms to make a joke. Here's an example:

He wears glasses during math because it improves divison.

You can see how important a mastery of homonyms is: without it, you'll never get to truly enjoy a joke like this:

When fish are in schools they sometimes take debate.

Samuel Johnson, a famous English writer,  once called puns, "the lowest form of humor" and the bad reputation stuck. But why? William Shakespeare wrote over 3000 puns and he's considered to be the gold standard when it comes to English literature. 

Walter Redfern, a very brilliant scholar,  said that, "To pun is to treat homonyms as synonyms".  As you may know, synonyms are words which have very similar meanings and the subject of LikeItIs!, our latest app in-the-making!