Using Colons in Sentences

Some punctuation marks, such as periods, question marks, and exclamation points, indicate the end of a sentence. However, commas, semicolons, and colons all can appear within a sentence without ending it.

The colon has a wide range of uses. The most common use is to inform the reader that whatever follows the colon proves, explains, defines, describes, or lists elements of what preceded the colon. Essentially, sentences that are divided by colons are of the form, "Sentence about something: list or definition related to that sentence."

In modern American English usage, a colon must be preceded by a complete sentence with a list, a description, an explanation, or a definition following it. The elements that follow the colon may or may not be complete sentences. Because the colon is preceded by a sentence, it is a complete sentence whether what follows the colon is another sentence or not.

In American English, many writers capitalize the word following a colon if it begins an independent clause—that is, a clause that can stand as a complete sentence. The Chicago Manual of Style, however, requires capitalization only when the colon introduces speech or a quotation, a direct question, or two or more complete sentences.

Other Uses of the Colon

In addition to being used in the middle of sentences, colons can also be used to visually separate information.

Separating Chapters and Verses 

A colon should be used to separate chapter and verse numbers in citations of passages in widely studied texts, such as epic poetry, religious texts, and the plays of William Shakespeare.

• Example: John 3:14–16 refers to verses 14 through 16 of chapter three of the Gospel of John.

Separating Numbers in Time Abbreviations

• Example: The concert begins at 11:45 PM.
• Example: The rocket launched at 09:15:05 AM.

Separating Titles and Subtitles

An appositive colon also separates the subtitle of a work from its principal title.

• Example: Star Wars Episode IV: A New Hope

Introducing Speech

Similar to a dash and a quotation mark, a segmental colon can introduce speech.

• Example: Benjamin Franklin proclaimed the virtue of frugality: "A penny saved is a penny earned."

This form can also be used in written dialogues, such as plays. The colon indicates that the words following an individual's name are spoken by that individual.

• Example: 

Patient: Doctor, I feel like a pair of curtains. 

Doctor: Pull yourself together!