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Comma Rules: 45 Dos and Don’ts of Comma Usage – Part 1

Where, oh where, did you put your comma? This little curly punctuation mark has caused a lot of nail biting over the years. You would think by now they would have come up with some comma rules to let everyone know how to properly use this cute little diddy.

Oh…wait. I just did that! And now I can share it with you.

Comma rules and comma usage-magoosh

Photo by Dvdgmz

We all know that commas create a pause in a sentence. This not only helps our reading to more closely resemble speech, but helps in our understanding as we read longer sentences.

However, commas have other uses, like separating grammatical parts of a sentence or even changing the meaning of a sentence altogether.

In part one of this two-part series on commas, I’m going to begin with the easy stuff. This will basically cover everyday comma usage. In part two, I’ll cover the more complicated, and lesser used comma rules used in sentences.

Comma Usage with Numbers

Do put a comma after every third number (counting from right to left).

    Out of 1,234 people, Gerald made $34,465.00 more than anyone else.

Don’t include a comma in a number if it is a page number, date, or street address.

Comma Usage with Dates

Comma rules with dates-magoosh

Do put a comma after the day of the year when writing out the year. If you are including the day of the week, do separate that from the rest of the date with a comma as well.

    January 17, 1965

    Wednesday, January 17, 1965

Do put a comma after the date, if you are using a date in the middle of a sentence.

    We waited until October 27th, 2015, for the landlord to fix the roof.

Don’t include a comma if the month and year are the only two parts of the date being used.

    The war ended in March 1465.

Don’t put a comma after the date if it’s used as an adjective. If the date is an adjective, most sources (but not all of them) say to put a comma after it. However, this practice seems awkward, as you will see below.

Do rewrite the sentence so as to avoid the awkwardness altogether (a better practice!).

    We went to the November 11th, 2017, assembly for no reason at all.

Correct, but awkward.

    We went to the assembly that was scheduled for November 11th, 2017, for no reason at all.

Better. Less awkward. But we can do even better.

    For no reason at all, we went to the assembly that was scheduled for November 11th, 2017.

Much better! And do you see how moving “for no reason at all” to the beginning of the sentence helped the sentence to flow nicely? I could have kept it at the end, but that simply doesn’t flow as well.

Names That Include Credentials

Do separate the credentials from the name with a comma. If the name with the credential appears mid-sentence, do place a comma after the credentials.

    We met with James T. Jones, RN.

    James T. Jones, RN, appeared before the judge.

Comma Rules for Addressing Someone Directly

Do separate the name of the person you are addressing directly with a comma.

    Thanks to you, Lori, we have a new dryer.

    We wanted to hand the ball to you, Fred.


Do use commas to separate the parts of an address. Do use a comma after the address if it is in the middle of the sentence.

    We went to Denver, Colorado, for our vacation.

Comma Rules for Lists

Do use a comma to separate each item in a list. And yes, I’m going to say that you do need to put a comma before the word and or the word or at the end of the list.

    My favorite vegetables are carrots, peas, and broccoli.

Don’t put a comma after the last item in a list.

    She had traveled to Denver, Atlanta, and New Orleans that summer.

A Note about the Oxford Comma

Now that last comma after “peas” or “Atlanta” is known as the Oxford comma. There is a lot of debate over including that comma before and or or – and some writers will omit it. However, omitting the comma can cause a lack of clarity in the sentence. Here’s an example.

    Her favorites Olympic sports are the relay races, sprints, running and hurdles.

In the sentence above, there should be four different sports listed. However, the reader is left to guess as to whether the last items, running and hurdles, are actually one sport or two. So it is best to get in the habit of always including that last comma to avoid any confusion.

    Her favorites Olympic sports are the relay races, sprints, running, and hurdles.

If you are writing for a publication of any kind, do find out whether your employer wants you to use the Oxford comma or not. It will likely be mentioned in the writing guidelines that are given to you when you begin an assignment. Some are picky regarding this little device, and while it is widely used, it is best to know what you are expected to do for any given job or assignment.


Do separate coordinate adjectives with a comma. Remember that if there is more than one adjective describing a single noun, they are said to coordinate. Here the comma usage is basically a substitute for the word and.

    It was a sumptuous, satisfying meal. = It was a sumptuous and satisfying meal.

Notice that both sumptuous and satisfying describe the meal. This rule applies even if there are more than two adjectives – just keep adding commas.

    It was an elegant, sumptuous, satisfying meal. = It was an elegant and sumptuous and satisfying meal.

If you feel the need to repeat the adjective or adverb in a sentence, do be sure to separate them with a comma.

    The flight home was really, really bumpy.

Don’t put a comma after a list of adjectives if they don’t each modify the noun.


    She had a dark, purple ribbon in her hair.


    She had a dark purple ribbon in her hair.

The ribbon wasn’t dark and purple, it was dark purple. Do you see the difference? “Dark purple” actually describes a singular color. It wasn’t light purple or lavender. It was dark purple.

It can be a subtle difference, but it is an important one. You can also think about the word dark being an adjective that describes the adjective purple (as opposed to describing the ribbon). That also would eliminate the need for a comma.

Attributive Tags

When you have a sentence that contains a direct quote or dialog, you will usually have an attributive tag like “they said” or “he exclaimed.”

If the attributive tag is before the quote, do place the comma after the tag but before the quote.

    I yelled to my friend, “Get over here and sit down!”

If the attributive tag is after the quote, do place the comma inside the quote.

    “Polly wants another cracker,” the parrot squawked.

Don’t insert a comma if the quotation or dialog ends with an exclamation point or question mark.

    “Where were you?” I yelled.

Don’t include a comma if the quotation is the subject or object of the sentence.

    Is “I forgot” the best excuse you can come up with?

Nonessential Information

Do separate information that is not essential to the sentence with a comma.

    Give the rough draft to your sister, Mary.

In the above sentence, the person with the rough draft only has one sister. Therefore, the name Mary is irrelevant. However, if the rough draft holder has more than one sister, don’t include the comma.

    Give the rough draft to your sister Mary.

If the nonessential information is in the middle of the sentence, do set it apart with commas on each side.

    Give your rough draft to your sister, Mary, so that she can proofread it.

Of course, if there is only one sister don’t put any commas – they are not needed.

    Give your rough draft to your sister Mary so that she can proofread it.


Sometimes you will use a parenthesis in a sentence to set off additional information. You don’t need a comma before or after the parenthesis. However, if the sentence would require a comma without the parenthesis, then do place the comma directly after the closing parenthesis.

    Before we bought the cat (the cutest one in the litter), we had to get Roger tested for allergies.


When an explanation of a noun occurs in a sentence, do set it off with commas.

    The insect, a spider with big hairy legs, is now crawling up your arm.

Which and That

Do separate the word which with commas, since it is a nonrestrictive pronoun.

    We went to the store, which wasn’t my idea.

    Jacob’s toys, which we bought on sale, are now all broken. (This shows that some of the toys that were bought on sale are now broken.)

Don’t set off that with commas. It is a restrictive pronoun.

    Jacob’s toys that we bought on sale are now broken. (This shows that the specific toys that were bought on sale are now broken.)

Introductory Words and Abbreviations, etc.

Sometimes, you will use introductory words like for instance, i.e., e.g., or namely. In cases like this, do use the comma before and after the introductory word. Do also use commas before and after the use of etc.

    We went to the zoo, namely, Audubon Park.

    You will want to pack warmly, e.g., a jacket, thick socks, and a sweatshirt.

    Jackets, thick socks, etc., are required for the ski trip.

For abbreviations like Inc. and Jr. that are part of a name, do place a comma between the name and the abbreviation.

    He came to the party with Billy Williams, Jr.

Don’t include a comma after abbreviations like Inc. and Jr.

    We went to Hallgraves, Inc. to buy a washing machine.


When writing a sentence and you introduce an interruption to that sentence, do set it off with commas.

    Your attitude about the situation is, quite frankly, disturbing.


When a word or phrase starts a sentence by answering a question or making a statement, do set it off with commas.

    No, you can’t have another cookie tonight.

    Once we found it, the hotel was even better than we expected.

A Note on the Use of Interruptions vs. Introductions

I need to add a note here regarding interruptions and introductions. In my experience both writing and editing, it is far better to use introductions rather than interruptions.

Interruptions are exactly that. They interrupt the thought that we are trying to convey. Now, in simple sentences that may not be such a problem. But in any writing that is more complex – like academic or professional writing – the interruption very often works against us.

Think of it this way. If you are in the midst of explaining any type of complex idea, putting an interruption in the middle of any of the sentences in your paragraph will have the effect of distracting the reader away from the point you are working to make. If you simply take that phrase within the commas and move it to the beginning of the sentence, you salvage all that you wanted to include in the sentence while NOT interrupting your reader’s thought process. Let’s look at our example.

    Your attitude about the situation is, quite frankly, disturbing.

Now that is a very simple sentence. But let’s move the interruption to the beginning.

    Quite frankly, your attitude about the situation is disturbing.

Hopefully you can see how the second example keeps the main idea together. Moving the interruption to the beginning of the sentence – and thereby making it an introduction – helps the flow of even a simple sentence. When the sentences become more complex, this method helps the readability of your writing tremendously.

So while this is not a rule – it is a very good practice to get into.

Afterthoughts and Question Tags

When a word or phrase appears after the end of the main clause of a sentence as an afterthought or a question tag, do separate it with commas.

    You did take out the trash, didn’t you?

    We thought the movie was just too violent, to be honest.

Wow! That was a lot of dos and don’ts, wasn’t it? No one said that the use of commas was simple! In its totality – it is a good bit of information to digest and remember. But if you bookmark this page then you will have a handy reference available when you encounter a comma question in your writing.

However – we’re not done! Keep an eye out for Part 2, with more comma rules and information on comma usage!

P.S. Become a better writer. Find out more here.

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