How to use a comma correctly? Use a Comma to Separate Items in a List: When you’re listing three or more items in a sentence, use a comma to separate them. For example: “I bought apples, oranges, and bananas.” The last comma before the conjunction (often called the Oxford comma) is optional, but it helps to avoid confusion. Use a Comma Before Conjunctions in Compound Sentences: If you’re joining two independent clauses (each with a subject and a verb) with a coordinating conjunction (like “and,”