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Comma rules

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Comma rules

In a nutshell

A comma is a punctuation mark that helps you make sentences less cluttered and easier to read. They do a number of jobs to make this happen. Commas can be used to separate items in a list, to separate coordinate adjectives, to separate clauses and lastly to punctuate direct speech. 

Commas and lists

Commas can be used when you want to separate items in a list. You can do this by simply using a comma after each item.


My bag contained shoes, a jacket, a hat and sunglasses.

Commas and adjectives

You can also use commas to separate coordinate adjectives. Coordinate adjectives are two or more adjectives of equal rank that modify the same noun. As a result of this, the order of the adjectives is not that important. 


The dangerous, preoccupied driver weaved through the city streets looking at his phone.

This can also be written as:

The preoccupied, dangerous driver weaved through the city streets looking at his phone.

Note: There is sometimes an order in which to write adjectives – particularly when multiple (three or more) adjectives are used before a noun – but don't worry about that now. Additionally, make sure not to place a comma after the last adjective in the sentence.

Commas and clauses

Subordinate clause

Before going into how commas are used to separate clauses, it's important to understand what a subordinate clause is. A subordinate clause is a clause that cannot stand alone as a complete sentence, it only adds additional information to the main clause. 

In the example below, the subordinate clause is highlighted blue (note how the clause cannot be a sentence by itself).


Before I start the movie, I like to eat the popcorn.

I like to eat the popcorn before I start the movie.

In most cases, when the subordinate clause is at the beginning of a sentence, a comma is placed after it. When the subordinate clause is at the end of a sentence, then there is no comma.

Main clauses and coordinating conjunctions

When a main clause is joined by a coordinating conjunction (for, and, nor, but, or, yet, so), you will also need to place a comma before the conjunction.


I went to the zoo, and Sam went to the chocolate factory.

Commas and direct speech

Direct speech

In case you forgot, direct speech is a report of the exact words used by a speaker or writer. These words are placed in between quotation marks ("...").

A comma is placed before introducing the speech.


The woman said, "What a cute dog."

Take note, if the sentence carries on after the speech, another comma should be used before the last set of quotation marks (unless the speech ends with a question mark or exclamation mark, in which case no comma is used).


The woman said, "What a cute dog," and continued to pet it.

The boy interjected, "Yay!" and opened his presents.

Comma splicing

A comma splice happens when you use a comma to connect two main clauses when, in fact, a full stop is needed. This is something you should avoid in your writing. A comma is simply not enough to show the relationship between two main clauses.


The house was on fire, I was horrified.

Which should actually be:

The house was on fire. I was horrified.

Alternatively, there are two ways you can fix this besides using a full stop:

Using a conjunction

You could add a conjunction immediately after the comma to connect the two clauses.


The house was on fire, and I was horrified.

Using a semi-colon

You could also change the comma to a semi-colon instead. Semi-colons are another good way to join two (related) main clauses together.


The house was on fire; I was horrified.

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FAQs - Frequently Asked Questions

What is a comma splice?

Where are commas used in direct speech?

How do I use commas in sentences with coordinating conjunctions?

Where do I place the comma in a sentence with a subordinate clause?

What is a comma?


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