Reading & Writing

Comma Rules

2 min readMedium5-question drill

Comma questions show up on nearly every test, and they're some of the most reliable points you can grab — once you know the four jobs a comma actually does, you stop guessing and start knowing.

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Comma Rules

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A comma's job is to separate parts of a sentence so the meaning stays clear. The test cares about a handful of specific situations. Master these and you'll handle almost every comma question.

First, some vocabulary. An independent clause is a group of words that could stand alone as a complete sentence — it has a subject and a verb and expresses a full thought (The dog barked). A dependent clause can't stand alone (Because the dog barked).

Here are the main comma rules the test checks:

1. Items in a list. Separate three or more items with commas: apples, oranges, and pears. The comma before and is fine and expected.

2. Setting off nonessential information. A nonrestrictive (nonessential) element is extra info you could delete and still have a complete, sensible sentence. Set it off with commas on both sides: Maria, who studies coral, won the prize. If the info is essential (you need it to know who/what is meant), use NO commas.

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Maria, who studies coral, won the prize.

Nonrestrictive (extra info)

A nonessential clause is set off by commas on both sides.

3. Joining clauses. To join two independent clauses you need either a comma + a FANBOYS conjunction (for, and, nor, but, or, yet, so) OR a semicolon. A comma alone between two independent clauses is a comma splice — always wrong.

Are both sides complete sentences?

Yes ↓

Is there a FANBOYS word (and, but, so...)?

Yes ↓

→ Use comma + FANBOYS

No ↓

→ Use a semicolon

No ↓

→ A comma alone may be fine — no semicolon

Deciding between comma and semicolon for joining clauses.

4. After an introductory element. Put a comma after an opening phrase or dependent clause: After the storm, we cleaned up.

The test also loves to make you NOT use a comma. A frequent trap: never put a single comma between a subject and its verb. The artist who painted this[comma] is famous is wrong — that lone comma splits the subject from the verb.

The artist who painted this mural is famous; however, few people know her name.

essential — no commassemicolon joins clauses

Essential clause takes no commas; 'however' takes a semicolon.

A strategy that works almost every time: read the choices and ask what is this comma (or semicolon) connecting? Identify whether each side is a complete sentence, whether the middle chunk is removable, and whether you're looking at a list. The punctuation follows from the structure — you don't have to 'hear' it.

Quick check

The artist's latest exhibition features landscapes painted in a style reminiscent of the Impressionists_______ however, her use of digital tools gives the works a distinctly contemporary feel.

Which choice completes the text so that it conforms to the conventions of Standard English?

—

;

Worked examples

Example 1

The museum's collection includes works by several renowned artists_______ Frida Kahlo, Georgia O'Keeffe, and Yayoi Kusama.

Which choice completes the text so that it conforms to the conventions of Standard English?

Example 2

Maria, who had been studying marine biology for over a decade_______ was the first to identify the new species of coral.

Which choice completes the text so that it conforms to the conventions of Standard English?

Example 3

The artist's latest exhibition features landscapes painted in a style reminiscent of the Impressionists_______ however, her use of digital tools gives the works a distinctly contemporary feel.

Which choice completes the text so that it conforms to the conventions of Standard English?

Common pitfalls

Comma splice with however/therefore

Words like however, therefore, and moreover are NOT conjunctions. Joining two independent clauses with a comma + 'however' is a comma splice. Use a semicolon before them instead.

Forgetting the second nonessential comma

If a nonrestrictive phrase opens with a comma, it must close with one too. Test makers often give you the opening comma and bait you into skipping the closing one.

Splitting subject and verb

A single comma should never sit between a subject and its verb. If you can't remove the chunk after the comma, the comma probably doesn't belong there.

Using a comma where info is essential

If deleting a phrase changes which person or thing you mean, it's essential — use NO commas. 'The student who cheated was expelled' needs no commas around 'who cheated.'

Key takeaways

A comma alone cannot join two independent clauses — use a semicolon or comma + FANBOYS.
Nonessential information gets commas on BOTH sides; essential information gets none.
Put a comma after an introductory phrase or dependent clause.
Never place a single comma between a subject and its verb.
Transition words like 'however' take a semicolon before them when joining two complete sentences.

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Try it yourself

5 practice questions on Comma Rules, drawn from the question bank. The tutor is one click away if you get stuck.

Where this lesson fits

Comma Rules

You are here

→Boundaries →Transitions →Form, Structure, and Sense