Most comma confusion comes down to six rules — learn these and you’ll punctuate the vast majority of sentences correctly. Commas separate ideas so a reader can follow your sentence without backtracking. Too few and the words run together; too many and the sentence stutters.
1. Separate items in a list
Use a comma between three or more items: “We packed bread, cheese, and apples.” That last comma before “and” is the Oxford comma — optional, but it prevents ambiguity, so we recommend keeping it.
2. Join two complete sentences with a conjunction
When two full sentences join with and, but, or, so, yet, put a comma before the conjunction: “The deadline moved, so we had more time.” If the second half can’t stand alone, no comma: “We worked late and finished early.”
3. After an introductory phrase
A comma follows an opening phrase or clause: “After the meeting, we revised the plan.” It signals where the warm-up ends and the main sentence begins.
4. Around non-essential information
Wrap extra detail you could remove in commas: “My manager, who joined last year, approved it.” If the sentence still makes sense without that part, fence it with commas.
5. Don’t splice two sentences with just a comma
This is the most common error: “It was late, we went home.” Two complete sentences need more than a comma — use a period, a semicolon, or add a conjunction (“It was late, so we went home”). The grammar checker flags these comma splices automatically.
6. Don’t separate a subject from its verb
Resist the urge to drop a comma between the doer and the action: “The report I finished yesterday , is ready.” No comma there.
When in doubt, check
Commas are where careful writers still slip. After drafting, run your text through the grammar checker — it catches splices, missing list commas, and stray ones. If a sentence needs several commas to work, it may be too long; the readability checker will flag it, and the paraphraser on Shorten mode can break it into cleaner pieces.
Punctuation isn’t about rules for their own sake — it’s about making your meaning land the first time.
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