The Oxford comma (or serial comma) is the comma placed before “and” (or “or”) in a list of three or more items. In “bread, cheese, and apples,” it’s the comma after “cheese.” It’s optional in English — but it can change meaning, so it’s worth understanding.
The famous example
Why it matters, in one sentence:
Without: “I’d like to thank my parents, Oprah and God.” (Reads as if your parents are Oprah and God.) With: “I’d like to thank my parents, Oprah, and God.” (Three separate things — clear.)
The Oxford comma removes that ambiguity by clearly separating the last item from the rest.
Who uses it
- Uses it: most US style guides (APA, Chicago, MLA), academic writing.
- Often drops it: journalism (AP style) and much British news writing — unless dropping it causes confusion.
Neither is “wrong.” It’s a style choice.
The simple rule
Pick one and be consistent across a document. Inconsistency — using it in some lists and not others — looks careless. If your school, publication, or employer follows a style guide, use whatever it specifies.
Our recommendation for general writing: use it. It prevents ambiguity at no real cost, and it’s never wrong to include it.
When it really matters
Even if you usually drop it, add it whenever a list could be misread without it. Clarity beats consistency in those cases — rewrite or add the comma so the meaning is unmistakable.
Keep your commas consistent
Serial-comma slips and other list-punctuation errors are easy to miss across a long document. After drafting, run your text through the grammar checker, and see our full guide to commas for the other comma rules that trip writers up.
One comma, one decision: choose your style, apply it everywhere, and add it whenever meaning is at stake.
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