Using Commas

Introduction

The comma is one of the most important punctuation marks in English, but it is often used wrongly. This page will introduce two of the most common uses of the comma: the conjoining use, and the listing use.

The listing use

When you write a sentence containing a list of items, you will need to use a comma to separate the items. For example:

He brought coffee, sandwiches, cheese and soda.

This sentence contains a list of four items. There are commas after coffee and sandwiches, to separate the items. After cheese, the word and is used instead; however, you can also include a comma BEFORE and if you like:

He brought coffee, sandwiches, cheese, and soda.

This comma is optional. However, you MUST include the word and.

The items in our example are all nouns, but almost anything can form a list in this way. Here are some more examples:

Type of list item	Example sentence
Noun	He brought coffee, sandwiches, cheese and soda.
Verb	She caught, cleaned, cooked and served the fish.
Adjective	The weather today is cool, dry and windy.
Verb phrase	I closed the door, started the car, pulled out of the driveway, and switched on the radio.
Clause	Mayuki made the sushi, Yung-Hee cooked the meat, and Izabella chopped the vegetables.

The conjoining use

When you join two clauses together with a coordinating conjunction (such as and, but, so, and or), a comma is usually placed before the conjunction:

It was raining, so I took my umbrella.

Here are examples using the most important coordinating conjunctions. You can get more information about coordinating conjunctions on the Basic Coordinating Conjunctions Web page.

Conjunction	Example
and	He lives in Victoria, and he studies at UVic.
but	John is Canadian, but Sally is English.
or	I could cook some supper, or we could order a pizza.
so	She was sick, so she went to the doctor.

Reversing the order of clauses

With conjunctions (such as because, as, since, while, and though) the dependent clause (the part beginning with the conjunction) can also come at the beginning of the sentence. In this case (and ONLY in this case), a comma can be used to join the two clauses together. Here are some examples:

Conjunction	Normal order	Reversed order
because	He doesn't need a car, because he lives downtown.	Because he lives downtown, he doesn't need a car.
since	She went to the art gallery, since the museum was closed.	Since the museum was closed, she went to the art gallery.
while	Gerry is married, while Cam is single.	While Cam is single, Gerry is married.