Comma and Its Usage

There are fourteen punctuation marks commonly used in English grammar. Of them, the comma is the one that is used incorrectly most often. And, there is little doubt as to why. There are so many different guidelines and rules pertaining to when or how a comma should be used, that many writers (especially those who are inexperienced) struggle with determining proper comma placement.

Do you use a comma between two nouns in a compound subject? What about between two verbs in a compound predicate? What exactly are comma splices anyways? Does the comma go before or after but? These are all legitimate questions, and luckily you don’t have to look too far for the answer.

We’ve compiled a list of all of the ‘comma rules’ so that you can improve your writing and get comma placement right every time.

A Short Guide to Comma Rules

Similar to how a period indicates the end of a sentence, a comma indicates a smaller pause. Think of a comma as an indicator of a soft pause, or a means of separating clauses, words or ideas inside a sentence.

As far as punctuation marks go, the comma is the most abused and misused. This is because many writers are unfamiliar, or confused, about what suffices as proper placement.

In order to hone your grammar and writing skills, we’ve put together a list of some of the most important rules of comma usage.

Rule 1: Using a comma with subjects and verbs

In nearly all situations, a comma should never be used to separate a subject from its verb.

Wrong: My cousin Jason, is a professional golfer.

As writers, we are sometimes tempted to add a comma between a subject and verb, as indicated in the example above, because when we speak we occasional pause momentarily at that point in the sentence. However in a sentence, when we write, place a comma here only makes the sentence sound awkward and uncomfortable.

Right: My cousin Jason is a professional golfer.

Rule 2: Using a comma between two nouns in a compound object or subject

It is not necessary to separate two nouns that appear together as a compound object or a compound subject.

Wrong: Stephen, and his hockey team will be playing in the playoffs next weekend.
Right: Stephen and his hockey team will be playing in the playoffs next weekend.
Wrong: My sister wore a dark blue dress, and black pumps to the dance.
Right: My sister wore a dark blue dress and black pumps to the dance.

Whenever an object or subject is comprised of two elements and the second element is parenthetical, set off the second element with commas. Use on before and another after. However, it is not necessary to use a comma when you are merely listing two elements.

Rule 3: Using a comma between two verbs in a compound predicate

A compound predicate occurs whenever the subject of a sentence is serving more than one purpose. If a compound predicate has two verbs, there is no need to separate them with a comma.

Wrong: Jake will play the guitar, and the harmonica.
Right: Jake will play the guitar and the harmonica.

This error is actually quite common, especially when the predicate is comprised of long verb phrases.

Wrong: I was supposed to stop after work and buy movie tickets, but was preoccupied.
Right: I was supposed to stop after work and buy movie tickets but was preoccupied.

There is no need to use a comma in a compound predicate, except when there might be a chance that the sentence may be misread.

Example: Kayla spotted her neighbor who turned onto the street, and smiled.

In the example above, it is okay to use a comma in order to make it clear that it was Kayla who smiled, not the neighbor.

Rule 4: Using comma splices

Whenever you need to connect to independent clauses, you need either a conjunction or a semi colon. A comma, on its own, is not enough to join the two. This type of error is referred to as a comma splice.

Wrong: We were out of bread, I went to the market.

A comma splice can be corrected with a conjunction, or by replacing the comma with a semi colon.

Right: We were out of bread, so I went to the market.
Right: We were out of bread; I went to the market.

Or, you might also choose to write the two independent clauses as two complete sentences.

Right: We were out of bread. I went to the market.

Rule 5: Using a comma after an introductory phrase.

A comma typically follows participial phrases that introduce a sentence.

Right: Grabbing her car keys, Sharon sprinted out the front door.

Whenever an adverbial phrase starts a sentence, it is typically proceeded by a comma, but this is not a ‘set-in-stone rule’, especially if it is short. Generally speaking, if the phrase contains more than four words, you should use a comma. You may also decide to use a comma with shorter phrases if you are using it for emphasis or to add a pause.

Right: At the end of the day, the teacher will be available to answer questions relating to the upcoming test.

However, if there is a chance that the phrase or sentence might be misread, use a comma.

Rule 6: Using a comma with a comparison.

Never use a comma before the word ‘than’ if you are comparing something.

Wrong: This cat weighs more, than that cat.
Right: This cat weighs more than that cat.

Wrong: Brand name peanut butter is more expensive, than generic peanut butter.
Right: Brand name peanut butter is more expensive than generic peanut butter.

Rule 7: Using commas with parenthetical elements or with interrupters.

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A parenthetical element is a phrase the contributes additional information to a sentence but could easily be taken away without changing its meaning. An interrupter, on the other hand, is like a thought bubble that pops up in the middle of a sentence to demonstrate tone, emphasis or emotion. Both of these elements should be set off with commas.

Wrong: The rain I was overjoyed to see was starting to clear.
Right: The rain, I was overjoyed to see, was starting to clear.
Wrong: Tara’s singing skills if you can call them that are torture for the ears.
Right: Tara’s singing skills, if you can call them that, are torture for the ears.

Rule 8: Using commas with a question tag.

A question tag is simply a single word or a short phrase that has been added to the end of a statement in order to turn it into a question. Oftentimes, writers will use question tags in order to persuade or encourage readers to agree with their opinions. A question tag should always come after a comma.

Right: The sound of the waves crashing against the pier in the morning is so calming, isn’t it?

Rule 9: Using a comma with a direct address.

Whenever you address someone by name, it is necessary to set off the name with commas.

Right: Dad, will you drive me over to Thomas’s house tonight after practice?

Rule 10: Using a comma with an appositive

An appositive is a phrase or word that refers to the same things as another noun in the sentence. Typically, the appositive offers additional information about the noun or helps to emphasize it in some way. If you were to take away the appositive without changing the meaning of the sentence, it would be considered nonessential and should be set off with commas. However, if the appositive is absolutely essential, is should not be set off by commas.

Nonessential appositive:

Right: My aunt, Sheila, is the best pie baker I have ever met.

Essential appositive:

Right: The Cranberry’s song Zombie is my favorite.

Rule 11: Using commas in dates.

Whenever you write the date as month-day-year, it is necessary to set off the year in commas.

Right: I was born on Saturday, September 25, 1982.

If you were writing it out as day-month-year, on the other hand, commas are not needed.

If you were to reference a specific day of the even and a date, a comma is needed.

Right: On Wednesday, June 10, at noon, there will be an important announcement for all staff members.

Rule 12: Using a comma between coordinate adjectives.

Whenever multiple adjectives modify a noun, they are considered to be coordinate and need to be separated by commas. It is easy to tell is adjectives are coordinate by switching their order. If the sentence still reads naturally, the adjectives are coordinate.

Right: His little sister was annoying, selfish and whiney. His little sister was selfish, annoying and whiney.

If the adjectives are not coordinate, they should not be separated by commas.

Wrong: The energetic, little girl was playing on the swings.
Right: The energetic little girl was playing on the swings.

Rule 12: Using a comma before but

A comma should be placed before but if it is used to connect two independent clauses.

Wrong: Rob is a good hockey player but he’s an even better football player.
Right: Rob is a good hockey player, but he’s an even better football player.

However, if but is not connecting two independent clauses, there is no need for a comma.

Rule 13: Using a comma before and.

Whenever you have a list that has only two items, there is no need to use a comma before the and.

Wrong: My best friend Amy is educated, and beautiful.
Right: My best friend Amy is educated and beautiful.
Wrong: My dog Felix can roll over, and sit.
Right: My dog Felix can roll over and sit.

If you are correcting a comma splice, that is connecting two independent clauses with a coordinating conjunction, you should add a comma before the and.

Rule 14: Using commas with lists.

Whenever you have a list that has more than two items, you should use commas in order to separate them.

Wrong: Kyle likes fast cars punk rock and kittens.
Right: Kyle likes fast cars, punk rock, and kittens.

Using the comma before ‘and’ in a list of three or more elements is a matter of personal preference.

The list might be comprised of nouns, like in the example above, or it could be made up of adjectives, verbs or clauses. Whatever it is made up of, use commas to separate them.