Commas
Commas are the most frequently used — and most frequently misused — punctuation mark in English. They signal a pause, separate items, and clarify meaning.
The main uses of commas
1. Separating items in a list
Use a comma between three or more items in a list. The comma before the final and (the Oxford/serial comma) is optional in British English but recommended for clarity.
She bought apples, bread, cheese, and milk.
He is tall, dark, and handsome.
We visited Paris, Rome, Berlin, and Madrid on our trip.
2. Before coordinating conjunctions joining two independent clauses
When a coordinating conjunction (FANBOYS: for, and, nor, but, or, yet, so) joins two independent clauses, use a comma before it.
She worked hard, and she passed the exam.
It was raining, but they went out anyway.
I wanted to help, so I stayed late.
No comma needed when the conjunction joins two verbs (one subject): She worked hard and passed the exam. (no comma — one subject, two verbs)
3. After introductory words, phrases, or clauses
However, she decided to stay. (introductory adverb)
After the meeting, everyone left quickly. (introductory phrase)
Although it was raining, they went for a walk. (introductory clause)
First, let me explain the situation. (introductory word)
4. Setting off non-essential (non-defining) information
Use commas to set off information that could be removed without changing the core meaning of the sentence.
My sister, who lives in London, is visiting this weekend.
The report, which was 50 pages long, was finally approved.
Dr. Patel, our family doctor, retired last year.
5. Direct address
Use commas when addressing someone directly by name or title.
Maria, could you please close the window?
Thank you, Doctor, for your help.
Let's eat, Grandma! (comma changes the meaning — without it: Let's eat Grandma!)
6. Direct speech
Use a comma between the reporting clause and the direct speech.
She said, "I'll be there at noon."
"Wait," he called, "I'm coming with you!"
Comma splice: Do not join two independent sentences with only a comma. She was tired, she went to bed. ✗ Use a semicolon, a conjunction, or a full stop: She was tired; she went to bed. ✓ or She was tired, so she went to bed. ✓