1. The Listing Comma
Used to list several items or ideas, one after another.
- We need two cucumbers, four tomatoes, some onions and a lettuce.
Then you should put a comma after each item of the list. In UK English, there isn’t normally a comma before and; in US English there often is. You can choose which style to follow.
This comma replaces the words and or or. You could say:
- We need two cucumbers and four tomatoes and some onions and a lettuce.
But this doesn’t sound nice, so we use commas instead.
Your list could include phrases, or even complete sentences. The principle is the same. For example:
- We spent our time relaxing on the beach, swimming in the sea and drinking coffee in the seaside cafés.
The listing comma is also used with adjectives before a noun in some cases, but not all. Look at two sentences:
- She has long, dark, shiny hair.
- He bought a bottle of dark German beer.
Why do we use commas in the first sentence, but not in the second? Remember: we said that the listing comma replaces the words and or or. You can say:
- She has long and dark and shiny hair (it’s correct, although it doesn’t sound good).
But you can’t say:
- He bought a bottle of dark and German beer.
So if you aren’t sure, ask yourself whether you can replace the commas with the words and or or. If you can, they are probably correct. If you can’t, then don’t use commas.
2. The Joining Comma
Used to join two complete sentences, together with a linking word.
- We were tired, and we really didn’t feel like going anywhere
In this sentence, each half of the sentence could stand by itself: We were tired is a complete sentence, and We really didn’t feel like going anywhere is a complete sentence, so we can put the two sentences together with a comma and the linking word and.
Other linking words you can use in this way include and, but, or or although.
However, you do need to be careful with these commas. You can’t use commas to join two complete sentences without using a linking word. You also can’t use joining commas with some linking words. Let’s practise; look at some sentences and see if they are right or wrong:
- 1. He seemed nice, but he just wasn’t my type.
- 2. I applied for the job, I really hope I get it.
- 3. She didn’t get the grades she needed, however she got into the university in any case.
- 4. You’ll either have to start again, or find someone to help you.
Sentences (1) and (4) are correct, (2) and (3) are wrong. (2) is wrong because there is no linking word between the sentences. We could say:
- I applied for the job, and I really hope I get it.
Or, you could use a full stop and separate the sentences:
- I applied for the job. I really hope I get it.
(3) is wrong because we can’t use the joining comma with the word however. The best way to write this sentence is with a full stop:
- She didn’t get the grades she needed. However, she got into the university in any case.
You might be thinking that (4) is wrong because the second part of the sentence isn’t a full sentence. That’s true, but the important point is that it could be a full sentence. You could say:
- You’ll either have to start again, or you’ll have to find someone to help you.
We shorten the sentence to make it simpler, so it’s OK to use the joining comma here.
3. The Bracketing Comma
Used to add an extra phrase or piece of information into a sentence. Often used in pairs.
- This book, first published in 1956, is still useful for students today —> We add the extra phrase first published in 1956 between a pair of commas
- One of my colleagues, who used to be a semi-professional footballer, invited me to play in their 5-a-side team this weekend —> We add the extra information who used to be a semi-professional footballer in between a pair of commas
To use bracketing commas, the sentence must make sense, and be grammatically correct, without the extra phrase or information. Let’s see this with our examples from before:
- This book is still useful for students today.
- One of my colleagues invited me to play in their 5-a-side team this weekend.
In both cases, the sentence is complete and the meaning is clear without the extra information. This makes it easy to see if your commas are correct or not.
If you are using commas in this way, ask yourself whether the sentence would make sense without the phrase in between commas. If not, something is wrong! For example:
- He was a strict, and sometimes cruel leader, who was feared by his staff.
If we remove the phrase between commas, we are left with:
- He was a strict who was feared by his staff.
Which is obviously wrong. Another example:
- Pens, which can write upside-down, are used by NASA astronauts on the International Space Station.
Here we have a different problem. The sentence makes sense without the extra information, but the meaning changes. If we just say:
- Pens are used by NASA astronauts on the International Space Station.
Saying that astronauts use pens in general is not a very interesting point! The extra information here is a key part of the meaning of the sentence, so it shouldn’t be between commas. We can’t remove the extra information without losing meaning.
If the extra phrase is near the beginning or the end of a sentence, you might just use one bracketing comma, instead of using a pair of commas:
- Similar to most people his age, he isn’t really thinking about his future. —> The first part of the sentence is the extra information, and because it comes at the beginning of the sentence, we just use one comma, not two.
- He told me that he wanted to quit and become a painter, which surprised me. —> The last part of the sentence is the extra information, so we put it between a comma and a full stop.
4. Common Mistakes with Commas
There are three mistakes which English learners often make with commas. Let’s look at them so that you can, hopefully, avoid making them!
1. Don’t put a comma between a subject and its verb:
- The people we met on holiday, were very nice. —> Incorrect
- Everything in those cupboards, needs to be packed in boxes. —> Incorrect
2. Don’t use a comma before that:
- She told me, that she wanted to move to London. —> Incorrect
- I had no idea, that he could speak Japanese! —> Incorrect
3. Don’t use a comma to join two sentences if you don’t use a linking word:
- I think this will be a good year, I’m sure of it. —> Incorrect
- He told me that he’s planning to go to the gym every day, of course he’ll give up in the first week. —> Incorrect
Continue learning with this Oxford Online English lesson on punctuation.