Using Colons

The Rules for Using Colons

A colon is used to extend a sentence to identify something previously mentioned, to introduce something (like a list), to divide a reference number or a time, or to introduce a quotation.

Table of Contents

Four Ways to Use Colons
Use of Colons Explained in Detail
(1) Using Colons to Extend a Sentence
(2) Using Colons after Introductions
(3) Using Colons in References and Times
(4) Using Colons with Quotation Marks
Video Lesson
Multi-choice Test

Four Ways to Use Colons

Colons are used in four ways:

(1) To extend a sentence in order to identify something previously mentioned in the sentence.

I demand one personal trait: discipline.

(2) After an introduction.

I have seen the following: ants, a cockroach, and a rat.

(3) In references, times, and titles.

Read Genesis 1:1 before 07:30.

(4) To introduce a quotation.

He said: "Curiosity killed the cat, but for a while I was a suspect."

Use of Colons Explained in Detail

Colons (:) are quite versatile. It is worth learning how to use them — especially how colons allow you to expand on an idea previously mentioned in the sentence. (If you can master this idea, you'll have a useful tool in your writing toolkit.)

(1) Using Colons to Extend a Sentence

Think of a colon (:) as the language version of an equals sign (=) in Mathematics. The information on the left of the colon equals the information on the right.

Usually, the information on the right is an expansion of whatever is mentioned on the left. For example:

He blamed his divorce on one thing: beer.
There are two reasons why I don't believe the alibi: there is no visa in his passport, and he is petrified of flying.

Sometimes, the ideas either side of the "equals sign" are a little harder to marry up. For example:

I have made an important discovery: alcohol, taken in sufficient quantities, produces all the effects of intoxication. (Playwright Oscar Wilde)

A Colon Is Like an Equals Sign

When using a colon to extend a sentence to expand on something previously mentioned in the sentence, think of a colon as an equals sign. For example:

I need one personal trait: discipline.
I would like to change just one aspect of your draft: the words.

Beware

You cannot introduce a new idea with a colon. For example:

I need one personal trait: I have others but not the one I need.
I would like to change just one aspect of your draft: then you can publish it.

(2) Using Colons after Introductions

A colon can be used after an introduction. The wording to the left of the colon will introduce whatever follows on the right. For example:

The Victorian printing set is missing the following characters: Q, R, K, and the question mark.
He voted for the following films:

(1) Jaws
(2) The Princess Bride
(3) Shawshank Redemption

Note: You cannot use a semicolon (;) for this purpose.

Read more about colons for introductions
Read more about using bullet points

(3) Using Colons in References and Times

Colons can be used to divide the parts of references, titles, and times. For example:

I am currently reading "How To Get Your Own Way: Who's Manipulating You?".
Genesis 1:1 starts "In the beginning God created the heavens and the earth."
07:30 - Breakfast
08:30 - Meet at the lake and prepare the kayaks
09:00 - Select teams

(4) Using Colons with Quotation Marks

Colons can be used to introduce quotations. For example:

It's hard to disagree with Frank Zappa, who said: "Art is making something out of nothing and selling it."

In this example, the quotation is introduced with a colon. However, it could have been introduced with a comma or with nothing. In creative writing, there is a lot of leniency on which punctuation to use before a quotation. You can let your desired flow of text determine whether you use a colon, a comma, or nothing. In more formal writing, however, a comma or a colon is expected after an introduction to a quotation. As a general rule, only use a colon if the introduction is an independent clause or the quotation starts with a full sentence.