Reading and Writing · 25 · Punctuation
Commas
Notes
Key points
- Comma + FANBOYS between two independent clauses.
- After an introductory word, phrase or clause: “After the rain, …”
- Around non-essential info: two commas, never one.
- Between items in a list of three or more.
- Between coordinate adjectives: a cold, dark night.
- Never a comma alone between two sentences — that's a splice.
- Never between subject and verb, or verb and object.
Rules
Comma after an introductory clause, not inside the main one.
When the bell rang, the students left.
When the bell rang the students, left.
Non-essential info: commas on both sides.
My brother, a pilot, lives in Oslo.
My brother, a pilot lives in Oslo.
Commas separate the items in a list.
The kit holds rope, a lamp, and a map.
The kit holds rope a lamp, and a map.
No comma between subject and verb.
The results of the trial surprised everyone.
The results of the trial, surprised everyone.
Common traps
- Adding a comma because the sentence feels long or you'd pause there.
- Using a single comma to join two complete sentences.
SAT tip
Every comma needs a reason: list, intro, extra info, or FANBOYS. No reason, no comma.
Test yourself
10 official SAT questions on Commas, easiest first.