In this grammar lesson, I would like to talk about that crucial comma. Even though the comma is such a tiny, little thing, it holds enormous power, able to completely change a sentence.

Example‘Let’s eat Grandma’ vs ‘Let’s eat, Grandma.’

No need to tell you that it’s imperative that a writer needs to know where to put commas. Some writers go with their gut feeling, putting the comma where they pause the sentence flow. As a non-native speaker, I find this tricky and prefer to stick to the rules. There are quite a lot, so I made an index to give you a better overview. I hope this text will make the use of the comma clearer for you.

Coordinating Conjunctions

Use a comma to separate independent clauses when they are joined by any of these seven coordinating conjunctions: for, and, nor, but, or, yet, so (the acronym FANBOYS).

ExampleI read a romance, and I bought a thriller.

Note that there is a comma before and, which some people frown upon. However, it is good grammar to use in this situation as both sentence parts before and after the comma + and are independent clauses.

If the subject does not appear in front of the second verb, a comma is generally unnecessary.

ExampleI read a romance and bought a thriller.

Some writers omit the comma if the clauses are both quite short.

ExampleI read the thriller and he bought a romance.

Many inexperienced writers run two independent clauses together by using a comma instead of a period. This results in the dreaded run-on sentence or, more technically, a comma splice.

IncorrectShe read the thriller, he read the romance.

There are several simple remedies:

CorrectShe read the thriller. He read the romance.

CorrectWhile she read the thriller, he read the romance.

CorrectShe read the thriller, and he read the romance.


Use commas wherever necessary to prevent possible confusion or misreading.

Example“I called you my love.”

Example“I called you, my love.”

ConfusingI saw that he was reading and had a coffee.

ClearerI saw that he was reading, and had a coffee.

Without a comma, the reader is liable to think that he was the one who had a coffee.

Dependent and Introductory Clauses

Use a comma after dependent clauses and introductory clauses, phrases, words or adverbs that come before the main (independent) clause.

ExampleIf you aren’t going to write a review, let me know now.

A comma is usually unnecessary when the sentence starts with an independent clause followed by a dependent clause (i.e. the other way around).

ExampleLet me know if you aren’t going to write a review.

Follow the same policy with introductory phrases.

ExampleHaving finally decided on the genre, I wrote my book.

ExampleI wrote my book having finally decided on the genre.

However, there are exceptions.

If the introductory phrase is clear and brief (three or four words), the comma is optional.

ExampleWhen in town we go to the bookstore.

Then again, always add a comma if it would avoid confusion.

ConfusingMonday evening writing classes were canceled.

ClearerMonday, evening writing classes were canceled.

Also, when an introductory phrase begins with a preposition, a comma may not be necessary even if the phrase contains more than three or four words.

ExampleInto the wonderful world of fantasy she vanished.

If such a phrase contains more than one preposition, a comma may be used unless a verb immediately follows the phrase.

ExampleBetween her red wine on the left and my white wine on the right, his beer glass stood proudly.

ExampleBetween her red wine on the left and my white wine on the right stood his beer glass.

Typical words and phrases starting a sentence which need to be followed by a comma are “however,” “on the other hand,” and “furthermore.” Starting a sentence with “however” with it having the meaning of ‘but,’ ‘yet,’ or ‘nevertheless’ is discouraged by many careful writers (as is replacing it by these words). A better method would be to use “however” within a sentence after the phrase you want to negate, as in the previous sentence. When you do this; however, the word however needs to be preceded by a semi-colon (like I did in this sentence).

ExampleI want to write English properly; however, I need to learn a lot to be able to do this.

Better yet is to avoid the use of however as much as possible as taking the word out often doesn’t mean there is loss of meaning.

ExampleI want to write English properly. I need to learn a lot to be able to do this.

Many adverbs can start a sentence and need to be followed by a comma. Adverbs end in “-ly” and answer the question “how?” How did someone do something? How did something happen?

ExampleAmazingly, there were even more books in the other room.

Introductory Words

Use a comma after certain words that introduce a sentence, such as well, yes, why, hello, hey, etc.

ExampleWhy, I can’t believe this!

ExampleNo, I’m not your love.

Use a comma before and after certain introductory words or terms, such as namelythat isi.e.e.g., and for instance, when they are followed by a series of items.

ExampleYou may be required to bring many items to the workshop, e.g., paper, pencils, pens, and erasers.

A comma should precede the term etc. Many authorities also recommend a comma after etc. when it is placed mid-sentence.

ExamplePaper, pencils, pens, and erasers, etc., are needed at the workshop.

Essential Elements

Do not use commas to set off essential elements of the sentence, such as clauses beginning with that (relative clauses).

ExampleThat you don’t read books is unimaginable.

That clauses after nouns are always essential. That clauses following a verb expressing mental action are always essential.

ExampleThe dog that attacked me scared me.

ExampleThe feeling that I got when reading that book was amazing.

Appositives (non-essential clauses, phrases, words)

Use a pair of commas in the middle of a sentence to set off appositives; clauses, phrases, and words (who, that, which) that are not essential to the meaning of the sentence.

ExampleI read a steampunk story, a kind of science fiction, today.

A kind of science fiction is the appositive, which gives more information about a steampunk story.

IncorrectJane who is my sister called me.

CorrectJane, who is my sister, called me.

If the appositive occurs in the middle of the sentence, both sides of the phrase need a comma. The closing comma is called an appositive comma. Many writers forget to add this important comma.

Following are two instances of the need for an appositive comma with one or more nouns.

IncorrectThe three shopping items, a bottle of wine, a French bread stick, and a French cheese were in my bag.

CorrectThe three shopping items, a bottle of wine, a French bread stick, and a French cheese, were in my bag.

ExampleJohn, who has a limp, was in a car accident.

If we already know which John is meant, the description is not essential and hence between commas. If we don’t know who is the subject of the sentence and need more information, i.e. it is essential, we don’t use commas.

ExampleJohn who has a limp was in a car accident.

We do not know which John is meant without further description; therefore, no commas are used.

This leads to a recurring problem. Look at the following sentence:

Example 1My sister Jane is here.

Now, see how adding two commas changes that sentence’s meaning:

Example 2My sister, Jane, is here.

Careful writers and readers understand that the first sentence means I have more than one sister. The commas in the second sentence mean that Jane is my only sister.

Why? In the first sentence, Jane is essential information: it identifies which of my two (or more) sisters I’m speaking of. This is why no commas enclose Jane.

In the second sentence, Jane is nonessential information—whom else but Jane could I mean? I have only one sister—hence the commas.

Comma misuse is nothing to take lightly. It can lead to a disaster like this:

ExampleMark Twain’s book, Tom Sawyer, is a delight.

Because of the commas, that sentence states that Twain wrote only one book. In fact, he wrote more than two dozen of them.

Commas in a Series

Use commas to separate three or more words, phrases, or clauses written in a series.

The comma is placed before of the coordinating conjunction introducing the last item of the series.

ExampleI read a romance, a thriller, and a horror novel last week.

Note: When the last comma in a series comes before and or or, it is known as the Oxford (or Harvard) comma. It is optional but ‘unofficially official’ in American English.

Don’t underestimate the power of the Oxford comma. Recently, workers won a court case with the Oxford comma tipping the balance in their benefit.

Separation of Coordinate Adjectives

Use commas to separate two or more coordinate adjectives that describe the same noun.

ExampleI read a big, heavy book when I was in hospital.

Be sure never to add an extra comma between the final adjective and the noun itself or to use commas with non-coordinate adjectives.

Only coordinate adjectives require a comma between them. Two adjectives are coordinate if you can answer yes to both of these questions:

1. Does the sentence still make sense if you reverse the order of the words?

2. Does the sentence still make sense if you insert “and” between the words?

Since I read a big, heavy book and I read a heavy, big book both sound fine, you need the comma.

Sentences with non-coordinate adjectives, however, don’t require a comma.

ExampleI finished the long-winded religious epistemology.

Long-winded describes religious epistemology as a whole phrase. This often occurs with adjunct nouns; a phrase where a noun acts as an adjective describing another noun—like ‘dance club’ or ‘summer sun.’

Commas for Contrast, Pause, Negation

Use a comma near the end of a sentence to separate contrasted coordinate elements or to indicate a distinct pause or shift / to offset negation in a sentence.

ExampleI wrote about a hero, not an anti-hero, in my book.

In this case, you still need the comma if the negation occurs at the end of the sentence.

ExampleI wrote about a hero, not an anti-hero.

Use a comma to separate a statement from a question.

ExampleI can write, can’t I?

Use a comma to separate contrasting parts of a sentence.

ExampleThat is my opinion, not yours.

Also, use commas when any distinct shift occurs in the sentence or thought process.

ExampleThe story sounded like a memoir, perhaps his own.

Use commas to set off expressions that interrupt the sentence flow (nevertheless, after all, by the way, on the other hand, however, etc.).

ExampleI am, by the way, not sure about this.

Free Modifiers

Use commas to set off free modifiers; phrases at the end of the sentence that refers back to the beginning or middle of the sentence. Free modifiers give more information but don’t make sense on their own. (They can be placed anywhere else in the sentence without causing confusion, but are a different type of modifier then).

ExampleI read a book late at night, which I enjoyed very much.

Geographical Names, Items, Dates, Addresses

Use commas to set off all geographical names, items in dates (except the month and day), and addresses (except the street number and name).

ExampleCleveland, Ohio, is a great city.

ExampleFebruary 29, 2017, was a strange day.

Even if you add a weekday, keep the comma after the date.

ExampleFriday, February 29, 2017, was a strange day.

ExampleFriday, February 29, was a strange day.

You don’t need to add a comma when the sentence mentions only the month and year.

ExampleFebruary 2017 was a strange month.

ExampleI work at 123 Park Ave. South, New York, N.Y. 10010.

Commas Used with Quotations

Use a comma to shift between the main discourse and a quotation.

If attribution (the main discourse/information about the quote) comes before the quote, place the comma outside the quotations marks.

ExampleThe beta reader said, “I found a grammatical mistake.”

If attribution comes after the quote, put the comma inside the quotation marks.

Example“I found a grammatical mistake,” said the beta reader.

If the attribution is within the quote, put the first comma within the first quotation marks and the second comma immediately after the attribution, outside of the second quotation marks.

Example“Why,” I asked, “don’t you read my book?”

If a quotation functions as a subject or object in a sentence, it might not need a comma.

ExampleIs “I don’t want to” all you can say to me?

ExampleSaying “I don’t like it” was a mistake.

If a quoted question ends in mid-sentence, the question mark replaces a comma.

Example“Will you still be my friend?” he asked.

Commas Used with Names, Nicknames, Terms of Endearment, Titles

Use a comma to set off the name, nickname, term of endearment, or title of a person directly addressed.

ExampleMy editor often asks, “My friend, is that book finished yet?”

Example“Will you, darling, write that article for me?”

Example“Yes, my friend, I will.”

Example“Good day, Captain.”

Traditionally, if a person’s name is followed by Sr. or Jr., a comma follows the last name.

ExampleMartin Luther King, Jr.

This comma is no longer considered mandatory. However, if a comma does precede Sr. or Jr., another comma must follow the entire name when it appears mid-sentence.

CorrectDoctor Doom Sr. is here.

IncorrectDoctor Doom, Sr. is here.

CorrectDoctor Doom, Sr., is here.

Similarly, use commas to enclose degrees or titles used with names.

ExampleDoom, M.D., is here.

Commas and Numbers

Use commas before every sequence of three numbers when writing a number larger than 999.

Example10,000 or 1,234,567.

Two exceptions are writing years and house numbers.

ExampleThe story plays in 1886.

ExampleHe lives at 123456 Long Beach, Miami.

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