English Grammar in Context – Tense Timelines, Mindmaps, Writing Tips, and More...

How to Use the Comma

The humble comma is often misused. It is an important mark, needed to indicate a pause and to help the reader avoid misunderstanding the flow and pace of your sentences. Without a comma, words tumble all over each other, and the arrangement of words, phrasal verbs and collocations, for example, are no longer distinguishable. Here are some helpful rules:

Create a short pause before the subject addressed - avoids confusing informationAll the best in your interview today, Tom.
Create a short pause before the subject addressed - avoids confusing informationWe're coming to the end of the quarter now, guys. It's crunch time!
Create a short pause before the subject addressed - creates focus and anticipationWe're coming to the end of the quarter. Now, guys, it's crunch time!
Create a short pause - sets context before attaching statementWhen you finish college, it will be raining.

Often, people will make the mistake of using a comma where a full stop or semicolon would better inform the reader as to your intended pace. Remember that a comma indicates a pause within a statement. A number of clauses comprising one statement - where the clauses clarify details or expand upon the opening information - can occupy a single sentence with multiple commas; but if there are two or more statements being made, they belong (for the most part) in separate sentences. Read through our examples and we'll explain your options as you go.

Example 1.1

All the best in your interview today. Break a leg!

These two clauses are arranged as two complete sentences. Yes, they are connected, but they have separate 'lives'. They can exist independently of each other. When this occurs, a full stop is your best option. If they absolutely should exist independently of each other, you should definitely use a full stop.

Example 1.2

All the best in your interview today, break a leg.

The reason this example is incorrect is that the pause is too short. In fact, it's so short that if we replaced 'break a leg' with anyone's name, the sentence would be grammatically correct:

All the best in your interview today, Tom.

In this sentence structure, 'break a leg' could mistakenly be read as a person's name! Remember, it's all about the length of your pause. If there is a comma, it doesn't indicate that you should change your tone to encourage someone by saying, "Break a leg!". Instead, it suggests that your tone doesn't need to change. Pauses can affect tone; and tone affects meaning.

Example 2.1

We're coming to the end of the quarter now, guys. It's crunch time!

In this first clause, the comma indicates that the reader should make a short pause before the word 'guys'. Now look at the restructuring of the sentence below:

We're coming to the end of the quarter. Now, guys, it's crunch time!

When the full stop closes the first clause at 'quarter', it slightly changes its meaning and suggests that the end of the quarter is not so close. The 'now' in the second clause moves it into the immediate present, and makes 'crunch time' much more imminent. 'Crunch time' is right now! However, the person is not speaking to the 'now guys'. Instead, by separating 'now' from 'guys' with a short pause, we can emphasise the time frame 'now' before addressing the subject 'guys'.

Example 2.2

We're coming to the end of the quarter now, guys; it's crunch time!

Some people choose to insert a semicolon between these two clauses, where a pause longer than a comma indicates a logical connection - a relationship - between the two clauses. This is perfectly acceptable, and the comma can stay in the same place as it is in the previous example. In fact, unlike the examples in 1.1 and 1.2, the semicolon helps the reader to slow down, and so the mistake won't be made that 'it's crunch time' could be someone's name.

Example 3

When you finish college, you should reach for the stars when setting your career goals.

The comma is placed after 'college' to achieve a comfortable short pause before providing instruction, but it shows us that a wide range of options could follow the opening clause. Also, a wide range of types of clauses could follow. You could make a simple statement:

When you finish college, it will be raining.

In this statement, the second clause tells us that the person is currently attending college, because a prediction of the weather is usually only made about the (immediate) present. Now look at this option:

When you finish college, there will be flying cars!

Here, the writer is making fun of how long the reader will take to finish college. The second clause pulls us forward into the (distant) future.

So, you can see that the first clause requires the second in order to make sense of it. This shows us the true purpose of the comma, as it prepares us for a clause that will explain or clarify or add more detail to the opening of the sentence. 

Example 4

It's time for me to head off means it's time for me to leave.

This is an 'explainer' sentence, many of which you will find across our webpages and in our videos. When you are explaining the meaning of something in a sentence, you can work right through the sentence without a comma, as we have done above. There is no need for a pause here. However, an explainer sentence can change when we are writing script or dialogue. Look at this example:

"I looked back at him and I said, 'Why did you throw that?'."

In this explainer sentence, the writer is describing a situation in which another person threw something and the writer (or narrator) responded with a question. You can see more on the use of quotation marks by clicking here, but the comma after 'said' prepares the reader for the quoted question. It works in partnership with the quotation marks so that the reader takes a pause and realises that another 'voice' is about to be used.

A note on the 'Oxford Comma'

The 'Oxford Comma' is placed before 'and' in a list (usually at the end). In this example, we have highlighted the Oxford Comma in the sentence. Note that it comes after the second last item in the list:

We went to the zoo, and there were monkeys, giraffes, elephants, and bears.

You can see how the commas keep the items in the list apart from each other. The Oxford Comma keeps the last two items apart, to avoid any possible confusion or making the mistake of pairing or grouping the two items.

A lot of people are choosing nowadays not to use the 'Oxford Comma', but in American English, it is generally preferred. Here is the same sentence without it:

We went to the zoo, and there were monkeys, giraffes, elephants and bears.

Here, the separate items in the list are still clear, but 'elephants and bears' constitute a pair, from a grammatical point of view. There are times when the pairing is purposely done, like in this example:

We went to the zoo, and in three enclosures, there were monkeys, giraffes, elephants and bears.

Here, there are three groups of animals across three enclosures:

  1. Monkeys
  2. Giraffes
  3. Elephants and Bears

So, our final word on using the 'Oxford Comma' is to ask yourself if your reader might be easily confused by the last two items in your list; and if those items could be mistakenly paired or grouped. If you think this mistake could be easily made, it might be best to use the 'Oxford Comma' for clarity.

For more on creating lists, see our page on the semicolon.

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