Using Commas Correctly

The comma is the busiest punctuation mark, and using it well makes writing clear instead of confusing. The editing questions test a handful of comma rules again and again, so learning those few patterns pays off quickly.

Commas separate parts of a sentence so readers can follow the meaning. Four uses cover most cases: between items in a list, after an introductory word or phrase, around extra information, and before a coordinating conjunction that joins two complete sentences. Knowing these four handles nearly every question.

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Lists, Introductions, and FANBOYS

Use commas to separate three or more items in a series: We bought apples, bread, and cheese. The comma before “and” is standard in formal writing. Use a comma after an introductory word or phrase that comes before the main clause: After the storm, the streets flooded. Wrong: After the storm the streets flooded. A short pause helps the reader, so add the comma. Corrected: After the storm, the streets flooded. Use a comma before a FANBOYS word (for, and, nor, but, or, yet, so) when it joins two complete sentences. Wrong: I called twice but no one answered. Two full clauses need a comma. Corrected: I called twice, but no one answered. Do not add one when the conjunction joins only two words: I called and waited needs no comma.

Setting Off Extra Information

Use a pair of commas to surround extra information that could be removed without changing the core meaning. This is called a nonessential element. Wrong: My sister who lives in Texas is visiting. If she is your only sister, the phrase is extra and needs commas. Corrected: My sister, who lives in Texas, is visiting. The key test: if you can lift the phrase out and the sentence still makes sense, set it off with commas. But if the information is essential to identify what you mean, use no commas: The student who scored highest won the prize needs the phrase to tell which student. Wrong: The book, that I borrowed, is overdue. That phrase is essential, so remove the commas. Corrected: The book that I borrowed is overdue.

Watch: A Short Video Lesson

Khan Academy gives a clear overview to go with this lesson:

A Routine for Commas

1. Add commas between three or more items in a list.
2. Add a comma after an introductory word or phrase.
3. Add a comma before a FANBOYS word joining two full sentences.
4. Surround truly extra information with a pair of commas.

Practice

1. How many items must a list have to need commas?
2. Where does a comma go with an introductory phrase?
3. When do you put a comma before “but”?
4. Fix this: “In the morning we left early.”
5. Fix this: “My car which is red needs gas.”
6. Does “The dog that barks lives here” need commas?

Answers

1. Three or more.
2. After the phrase, before the main clause.
3. When it joins two complete sentences.
4. “In the morning, we left early.”
5. “My car, which is red, needs gas.”
6. No — the phrase is essential.

Where This Fits in Your RLA Prep

Commas work alongside other punctuation marks and support fixing run-ons and comma splices. See every topic on the Language Arts Prep Hub.

Recommended Prep Books

Keep building momentum with a full study guide and practice tests:

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