The Ultimate Guide to Colons (:)

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What's discussed in this post

Introduction
Basic functions
Basic function 1: to introduce a series or list
Basic function 2: to separate numeric terms
Basic function 3: to separate a title and subtitle
Basic function 4: to introduce a quotation, or to separate a formal greeting from the message
Stylistic Functions
Stylistic Function 1: to create an informal tone
Stylistic Function 2: to illustrate or add emphasis
Stylistic Function 2: to add sizzle
Other editorial considerations
Colons and capitalization
Colons and other punctuation
Further study

​Introduction

It is my personal opinion that colons are the most underrated punctuation mark. Many authors avoid using it, probably because of how it was introduced in grade-school English class: with limited functionality and formal tone, so it seems incompatible with fiction writing, which generally has an informal tone.

But the colon can be used effectively in fiction writing to create an informal tone and drama. This guide is meant to help you understand the colon’s basic and stylistic functions, as well as the editorial considerations regarding the colon, such as capitalizing, typeface, and other punctuation, so that you can use it with confidence as part of your writing stylekit.

Basic functions​ 

Here is an overview of the basic functions of the punctuation, the colon.

​Basic function 1: to introduce a series or list

A colon (:) is used to introduce a series or list. The introductory clause before a colon must be an independent clause (complete sentence) and can include phrases such as “the following,” and “as follows.” The list or series the colon introduces can consist of words, phrases, and clauses (even independent ones).

Basic function 2: to separate numeric terms

​A colon is used to separate the following numeric terms:

• Specific time (9:31 a.m.)
• Time elapsed (She swam the 50 free in 28:21.18.)
• Books and verses of the Bible (John 3:16)
• Legal citations (Municipal code 6:413)
• Ratios (2:1 for 2-to-1)

Basic function 3: to separate a title and subtitle

In running text and other citations, a colon is used between the main title of a book and its subtitle (The Best Punctation Book, Period: A Comprehensive Guide for Every Writer, Editor, Student, Businessperson).

Basic function 4: to introduce a quotation, or to separate a formal greeting from the message

A colon is commonly used to introduce quotations following a complete sentence, especially if the quotation is a block quotation. 
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A colon can also be used after a formal greeting within an email, letter, or other missive (Dear Mr. Darcy:).

Stylistic functions

Colons can also be used stylistically to create an informal tone and add drama. Use these stylistic functions sparingly in your fiction writing: if they are used too often, they will lose their effect!

Stylistic function 1: to create an informal tone

Some of the colon’s basic functions can be used to create an informal tone in the following ways:

• A fragment can introduce a series or list (think of a pros and cons list)
• A colon can introduce an independent clause following a list as part of an inverted sentence (although an em dash is more standard here)
• A colon can be used to introduce text messages, or to create an emphasis between narration and dialogue.
• Use a colon to illustrate a sarcastically formal greeting in dialogue.

Stylistic function 2: to illustrate or add emphasis

A colon (:) can be used between two independent clauses in the same way a semicolon (;) is. In fact, sometimes they are interchangeable, but it’s important to note that while a semicolon represents the coordinating conjunction “and,” the colon represents the subordinating conjunction of “because.” Therefore, the clause that follows the colon should answer, amplify, or illustrate what precedes the colon.

Stylistic Function 3: to add sizzle

To understand this stylistic function of the colon, we must first go over the type of pause the colon creates and what punctuation signal the colon represents when it’s used between two clauses. The easiest way to do this is to compare it to the semicolon (;). Like the semicolon, the colon creates a pause that’s somewhere between the quick breath of a comma and the full stop of an ending punctuation mark (period, question mark, and exclamation point). But a colon represents a different type of signal than a semicolon. While a semicolon represents the flashing red signal of “and,” a colon represents a flashing yellow signal of “proceed.”

In other words, the colon prepares the reader’s mind for something that is coming. It creates anticipation, expectation, and excitement. It creates sizzle.

This function is most commonly used when a colon connects two independent clauses. But it also allows you to use the colon to add drama while introducing a dependent clause. Just make sure the dependent clause elaborates on the statement in the introductory clause!

​Other editorial considerations

This section offers a brief overview of the editorial considerations you must be aware of when you incorporate colons into your writing.

​Colons and capitalization

Whether or not to capitalize what comes after a colon is based on syntax:

• If the text before the colon is not a complete sentence, the text after a colon should be lowercase (with the exceptions of dialogue, quotations, and a proper noun). Pros: flexible hours, open office, hot receptionist.
• If the text before the colon is a single, complete sentence, but what comes after the colon is not a complete sentence, then it should not be capitalized (with the exceptions of dialogue, quotations, and a proper noun). She filled her cart with items on her grocery list: 3 pints of Eagles ice cream, scotch, and Splenda.
• If the text before the colon is a complete sentence and the colon introduces multiple complete sentences, then the text after the colon should be capitalized. The weather was perfect for a beach day: It was sunny. It was hot, but it wasn’t humid.
• If the text before a colon is a complete sentence and the text after a colon is a complete sentence that could be separated from the first without changing any meaning, the text following the colon should be lowercase. This is called “book style,” and it differs from the capitalization of a series of sentences because the sentence after the colon is considered still the same sentence as the sentence before the colon.

​Colons and other punctuation

The colon can be used in conjunction with parenthesis, quotation marks, exclamation points, and question marks:

• You can use a colon after a closing parenthesis. She looked good (almost divine): he couldn’t help himself.
• When a quotation is not dialogue, a colon only comes after the closing quotation mark. She looked too “good”: he couldn’t help himself.
• You can use a colon to introduce dialogue. He couldn’t help but say: “You look too good.”
• A colon can only be used with question marks and exclamation points when they are part of a proper title. In this case, the colon follows the question mark or quotation mark. Here’s how he responded to How the Grinch Stole Christmas!: tears, cries, and boredom.

Further study

The Copyeditor’s Handbook, 4th edition, Pg. 128
The Chicago Manual of Style, 17th edition, 6.61–6.67
The Best Punctuation Book, Period, Chapter 4: Colon