Grammar Guide #8: Correct Use of the Comma
I have spent most of the day putting in a comma and the rest of the day taking it out. — Oscar Wilde
A couple of people asked me to write a grammar guide on comma use. Seeing as a lot of people struggle with punctuation, your wish is my command.
In writing, commas are especially important when it comes to making yourself understood and aiding readability. There are quite a few rules as to when you should use commas. I’m going to go through the most important ones in brevity, and provide you with sample sentences, as well as additional explanations when they are needed. I have purposely left a rule or two out, considering I thought them too nitpicky, and I have probably forgotten some, but hopefully I’ve managed to cover most of it.
1. Use a comma to separate the elements in a series of three or more words or word groups
Make sure to use a comma before all of the elements, including the last one. The last comma, before the word ‘and’, is called an Oxford comma or serial comma. Leaving the last comma out is acceptable, but there are situations (for example if there are a lot of items on the ‘list’) in which it makes the sentence less confusing. Using the Oxford comma in fiction is generally recommended.
- I had lunch with Isabella, Catherine, Robert, and Michael.
- He bought apples, cheese, and ham at the grocery store.
- Anna visited the gym, the hair salon, and finally the cinema.
- John has lived in the US, England, Spain, Italy, and Sweden.
2. Use a comma to separate adjectives when the word ‘and’ can be inserted between them
- She is a strong, independent woman. (She is a strong and independent woman.)
- My grandmother lived in a cosy old house. (You wouldn’t say ‘cosy and old house’, so no comma.)
3. Use a comma and a small conjuction (and, but, for, nor, yet, or, so) to connect independent clauses
- I really like him, but he’s not the marrying kind.
- Josh told me that he loves playing football, and that he is going to pursue it professionally.
- The little girl could neither write, nor read.
4. Use commas to separate a subordinate clause from the main clause
The subordinate clause is often a parenthetical element, which can be removed without changing the meaning of the sentence. Often it provides additional information aside from what is already said in the main clause.
- Vanessa, bless her soul, died in a car accident last year. (Vanessa died in a car accident last year.)
- The Golden Gate Bridge, which is located in San Francisco, was closed for a couple of hours this afternoon. (The Golden Gate Bridge was closed for a couple of hours this afternoon.)
- I knew that President Clinton would resign, because of the Lewinsky scandal. (I knew that President Clinton would resign.)
- Even though the boy is very clever, he wasn’t able to climb the tree. (He wasn’t able to climb the tree.)
5. When you address a person directly, use commas before and after their name or title
- Hey, Karen, can you help me out?
- Yes, mother, I’m coming.
- No, Mr. President, the senator hasn’t arrived yet.
6. Use a comma to separate the day and month from the year in dates
Make sure you use the comma after the year as well. If any part of the date is left out, also disregard the comma.
- When Carmen and José met on December 5th, 2000, it was love at first sight.
- Carmen and José met in December 2000.
- My birthday is on July 21st, 1986.
7. Use a comma to separate the city from the state, as well as after the state
If you use the two letter capitalized acronym of the state’s name, you don’t need a comma.
- She lived in Detroit, Michigan, for the past ten years.
- I have never been to Los Angeles CA.
8. Use commas around titles or degrees used in combination with a name
Jr. and Sr. don’t require commas, and neither do Roman numerals such as I, II, III and so forth.
- Gregory House, M.D., is a surly doctor on television.
- My father knew Sammy Davis Jr.
- The movie was produced by Buzz Feitshans IV.
9. Use a comma to separate quoted elements
- The girl told him that he had no talent, upon which Kanye replied, “I’m Kanye West. That doesn’t make sense.”
- A journalist wrote, “The healthcare system is not as developed as it could be.”
- "I don’t like you very much," she said.
10. Use commas to separate elements that disrupt the flow of the sentence
- She had spent the day working on yet another, in her eyes, pointless article.
- The apple, as you may have noticed, doesn’t fall far from the tree.
- Mr. Johnson was, however, not too bright.
11. Use commas to separate elements that display contrast
- This matter is neither black, nor white.
- She wondered whether she should go left, or right.
- That’s his car, not hers.
12. Use a comma after phrases that are longer than three words and begin a sentence
If the first phrase has less than three words, the comma isn’t necessary.
- When it comes to the constitution, I’m no expert.
- He went looking for the pot of gold at the end of the rainbow, but didn’t find it.
13. Use a comma to separate two sentences if it will help avoid confusion
- I wished for a bicycle, and my sister wanted a Barbie doll.
- He wanted to play chess, but she rather played checkers.
- For most students, the exams are already over.
14. Do NOT use a comma to separate two independent clauses
A comma splice occurs when a comma is used between two independent clauses, rather than separating them into two. When you connect two independent clauses without using any punctuation whatsoever, it becomes a run-on sentence. Both run-on sentences as well as comma splices are grammatically incorrect. You can read more about run-ons and comma splices here.
- Incorrect: I woke up late this morning, I didn’t have time for breakfast (comma splice). OR I woke up late this morning I didn’t have time for breakfast (run-on sentence).
- Correct: I woke up late this morning, and I didn’t have time for breakfast. OR I woke up late this morning. I didn’t have time for breakfast. OR I woke up late this morning; I didn’t have time for breakfast.
15. Use a comma when you begin a sentence with introductory words (yes, well, now)
- Well, you see, I was very tired that evening.
- Yes, you can borrow my copy of Jane Eyre.
16. Use commas to separate words such as however, therefore, though etc when they are used in a disruptive manner
- If you ask me, however, I think cucumbers should be banned.
- I don’t know, though, what did she think about the event?
- And, therefore, you should ask me before you take my car.
17. Use a comma or semi-colon before introductive words (that is, namely, for example, for instance, e.g., i.e., such as) when they are followed by a list of items
A comma is used after the introductory word.
- The store lacks several supplies; for instance, milk, bread, eggs, and salad.
- She packed her bag full of various items, for example, clothing, toiletry, a hairbrush, and her favorite book.
Like I mentioned at the beginning of this guide, there are so many rules as to when you should use commas; making it impossible to cover them all. And admittedly, even I don’t know all of them.
One important thing to remember, though, is the fact that commas introduce a pause in reading. Therefore, you should be careful not to use too many. An overuse of commas makes reading your text more difficult. That’s why it’s sometimes better to separate longer sentences into several shorter ones, rather than using a lot of commas.
If you want to practice comma use, you can find a quiz here.