A comma is an element of punctuation. It is symbol that we write within a sentence.
We write a comma on the base line of the text. A comma represents a pause in speech. In the above example, you would pause very briefly after “apples” and before “pears“. Therefore commas act as separators to different parts of a sentence.
There are many situations in which we use commas in English. Here are the most common:
Vocative case
The vocative case is used to address someone directly. We use a comma to separate the vocative case from the rest of the speech.
Example:
“Mark, please tidy your bedroom.”
In the above example, “Mark” is the vocative case because we are addressing Mark. We are talking directly to Mark. We say his name, then we pause (represented by the comma) and then we continue with our request.
We can also put the vocative case (separated by a comma before it) at the end of the sentence:
Example:
“Please tidy your bedroom, Mark.”
An example situation to show the importance of commas:
“Let’s eat, grandma.”
(There is a comma before “grandma” so “grandma” is the vocative case. We are telling grandma that we want to eat. )
“Let’s eat grandma.”
In the second sentence, there is no comma. Therefore there is no vocative case. We are no longer addressing grandma. Grandma is now the object of the verb “eat”. We are going to eat grandma!
Conclusion: Commas save lives!
Commas for lists
We use commas to separate a list of items, places, things, ideas etc.
Without commas:
Jane is going to visit London and Paris and Rome and Madrid.
(This is bad style because we are repeating the word “and”).
With commas:
Jane is going to visit London, Paris, Rome and Madrid.
We use a comma to separate each element of the list.
“and” separates the last 2 items in the list.
There is no comma before “and” at the end of the list.
The Oxford comma
As mentioned above, there is usually no comma before “and” at the end of the list. However, this is not a strict grammar rule. It is a rule of style and it is acceptable to put a comma in this position:
Example:
Jane is going to visit London, Paris, Rome, and Madrid.
The last comma before “and” is called the “Oxford comma” or “Harvard comma” or even “Serial comma”.
There are arguments for and against using this Oxford comma. It adds clarity in certain situations but purists don’t like seeing a comma before “and”. For information, most journalists do not use the Oxford comma.
If you are preparing for an English exam, my advice would be to ask your teacher whether or not you should use the Oxford comma. If you are a journalist, you should ask your editor. In most other cases, it comes down to personal choice.
Adjectives after a noun
We always use commas for 3 or more adjectives after a noun.
Example:
The actor is tall, slim and handsome.
Adjectives before a noun
When the order of the adjectives before a noun is NOT fixed, we use commas.
(The order of the adjectives is not fixed when the adjectives give the same type of information.)
Example:
A slim, tall woman is crossing the road. 
We can also say:
A tall, slim woman is crossing the road.
In the above example, the adjectives “slim” and “tall” give the same type of information (both describing physical size)
We do not use commas when the order of adjectives is fixed.
(The order of the adjectives is fixed when the adjectives give different types of information.)
He drives a small red Italian car.
He drives a small, red, Italian car. 
In the above example, the adjectives “small“, “red” and “Italian” give 3 different types of information (size and colour and origin).
Discourse markers
Discourse markers connect, organise and manage what we say or write. They also express attitude.
Examples of discourse markers:
anyway
well
firstly
furthermore
in addition
in conclusion
moreover
surprisingly
We usually use a comma after a discourse marker at the start of a sentence.
Example sentences:
Surprisingly, Mark failed his driving test.
“Anyway, I’m too tired to go out tonight.”
Non-defining relative clauses
Example:
Oxford street, which is in London, is closed today.
“which is in London” is a non-defining relative clause.
The clause gives us non-essential information about Oxford street.
We separate it from the main sentence (“Oxford street is closed today.”) with commas.
Direct speech
If the reporting clause is before the direct speech, we write a comma before the direct speech.
Example:
Mark said, “I am going to London.”
If the reporting clause is after the direct speech, we write a comma before the closing inverted commas.
Example:
“I am going to New York,” Jane said.
Conditionals starting with “if clauses”
We use commas for conditionals that start with an “if clause“.
Example:
If it rains, I will take my umbrella.
We do not use commas for conditionals that end with an “if clause“.
Example:
I will take my umbrella if it rains.
To emphasise contrast
We use commas to emphasise a contrasting idea or subject. The comma forces a pause and that pause helps us to separate contrasting ideas.
Words that often express contrast:
never
not
unlike
Examples:
This is my phone, not yours!
Mark, unlike Jane, is a fast runner.
Numbers
We use commas to separate thousands:
$1,000,000
(One million dollars)
There are 26,300 students enrolled at Sheffield University.
(twenty six thousand, three hundred)
More lessons
English speaking practice with a native English speaker
IELTS tips and advice from a successful student
Direct speech writing rules in English
Adjectives and their position in a sentence
Common English proverbs
List of all the lessons
