Commas are the bane of many writers. Native speakers often trip over this punctuation mark, and ESL students struggle with it even more. So in this post, I will try to reduce this enigma to its essential parts.
NOTE: This post is strictly for writing in American Standard English. The Queen’s English sometimes differs.
The rule many people learn is to put a comma where you would naturally pause or take a breath. Let’s go into more detail.
When two parts of a sentence each have a subject and verb separated by a conjunction (and, but, or, so, since, etc.), then put a comma right before the conjunction.
Our team won the tournament, and I got a trophy.
Some conjunctions can appear in the middle of a sentence for emphasis or context. When you have this situation, use commas on both sides of the conjunction.
I went to get my visa yesterday. I didn’t have all of my paperwork, though, so I have to go back tomorrow.
Too and as well are not actually conjunctions, but the same comma rule applies.
I want some, too!
John ran the report, and he checked it for accuracy, as well.
If a list is only two items, then there is no comma (Jack and Jill). When the list is three or more, use commas to separate the items from each other (Jack, Jill, and Spot). Notice the comma before “and.”
Some Americans were taught the British rule, which is to omit the comma preceding and (Jack, Jill and Spot). I think it is most important to be consistent. If I see it both ways in the same document, I consider the omission to be a typo.
Sometimes you have a list of verbs, which can be confusing. If the same subject is doing all of the verbs, then follow the comma rule for a list.
Our team won the tournament and got a trophy. (no comma in list of 2 verbs)
Our team won the tournament, got a trophy, and threw a victory party. (commas separating items in list of
I swept, mopped, and polished the floor. (commas separating items in list of 3 verbs)
3. Dates and Places
When Americans write dates, we write Month Day, Year.
Jan. 1, 2013
We also divide a city from the state where it is located with a comma.
4. Introductory Phrases and Clauses
If you give a context before your main idea, put a comma before the main idea. Here’s the test: do those words make as much sense at the end of the sentence as they do in the beginning? If so, put your comma right after your introductory phrase or clause.
After we received more information, we changed out minds.
TEST: We changed our minds after we received more information.
Time references are part of this category, too.
In time, you will learn to write better.
Yesterday, we went to ….
On Dec. 7, 1941, ….
Notice that the last example applies two rules:
a comma within the date
a comma where the introductory phrase ends (after the year)
5. Addressing People
If you are communicating with someone (or a group), use commas before / after the name. For instance:
Oh, Mary, I forgot ….
Spot, lie down.
My fellow Americans, ….
For if … then sentences, put a comma right before then. This is where you stop describing the condition and start describing the outcome.
If I wash the dishes, then my wife will be happy.
7. Dependent Phrases and Clauses
If you are giving extra information, then put commas before and after.
John Smith, my childhood friend, is visiting this weekend.
John Smith, who has been my friend since childhood, is visiting this weekend.
John Smith is a person with many attributes. The fact that he is my childhood friend is just one of his many attributes. And in this sentence, it is extra information for the reader.
However, if the information is necessary to identify someone or something specific, leave out the commas.
My childhood friend John Smith is visiting this weekend.
I have many childhood friends (one would hope). So without the name John Smith, the reader would
be confused about which of my friends is visiting. In this case, the name is necessary.
If you use the word like to indicate examples, put a comma before it and at the end of the examples.
TEST: Can you substitute such as?
Innovative ideas, like those in TED talks, can change the world.
TEST: Innovative ideas, such as those in TED talks, can change the world.
However, if you use “like” when making a comparison, there is no comma before “like.”
Love is like a red, red rose….
If you quote someone in the middle of a sentence, then insert a comma right before the quote starts.
Patrick Henry said, “Give me liberty, or give me death!”
10. Responses and Interjections
Use commas to separate yes/no responses and interjections from the main idea.
Yes, I’d like that.
No, that’s not mine.
Oh, I didn’t think of that.
Ugh, I hate that!
I hope this demystifies the confusion about commas. Good luck in your writing!
Hint: If you want to look at examples, search this page for “,” to see how I use commas.
Liam Hickey currently teaches ESL with Corporate English in Guadalajara, Mexico. Via Willpower Careers, Liam also works as a career coach, teaching people how to write effective résumés, research companies, interview and negotiate salary, network, and more. His clients also benefit from his ten years of technical writing and consulting experience.