Chapter 3-3-1: When to Use a Colon
The colon (:) is "les deux points" in French. It focuses the reader's attention on information that follows it. It is important to remember that you may only use a colon after an independent clause if it is used in a sentence, although titles have a different rule. You use a colon whenever more information can be expected. On this page, there are explanations for three main situations in which the colon is used: to introduce a list, to set off a quotation, and to define or clarify meaning.
One way you can use a colon is to introduce a list after a complete independent clause. Often times, readers will be expecting more information when the independent clause ends with “the following” or “as follows”:
He visited three cities during his stay in the Maritimes: Halifax, Saint John, and Moncton.
The courses I am taking this semester are as follows: English, sociology, economics, political science, and psychology.
In order to bake a cake, you need the following basic ingredients: flour, milk, eggs, and baking powder.
A second way a colon can be used is to set off a quotation:
The driving teacher left us with one last message: “Never fall asleep at the wheel!”
My best friend George left me a message on my answering machine: “Hey, it’s me. Call me back.”
My father always says the same thing when I leave: “Be careful!”
A colon can also be used to define or clarify meaning. In these examples, notice how the colon serves to throw the reader’s attention forward. An independent clause may follow the colon, although this is not necessary:
The reaction of the crowd signified only one thing: apathy.
Their lobbying efforts were ultimately useless: the bill was soundly defeated.
My mother gave me one good piece of advice: to avoid wasting time and energy worrying about things I cannot change.
Apart from the three functions of the colon mentioned above, there are also a few other formatting situations in which the colon may be used.
Remember that colons can be used in titles, connecting the main title with a subtitle.
Titles do not contain an independent clause. A sentence must contain an independent clause, so notice that sentences and titles will look different.
Titles do not need any particular structural items such as verbs, subjects, or end punctuation.
Amazing Escapes: lucky survivors and what they learnt
Winter Soups: meals for your soul
Dogs: the animals we know as man's best friend
The colon may also be used in the salutation of a letter when writing in the formal register:
Dear Sir or Madam:
To whom it may concern:
Dear Professor Miller:
The colon is used when writing the time, inserted between the hour and minute:
Tours of the chocolate factory are available every morning at 9:45.
Our office is open from 9:30 AM to 5:30 PM, seven days a week.
We are out to lunch! We will be back by 1:15.