A colon is a punctuation mark used to separate significant parts of a sentence, particularly when the first part offers a sense of anticipation for the second. This form of punctuation is also used in other conventional applications as noted below.

Use the colon when the first sentence anticipates the second sentence or phrase, thereby creating an emphatic tone.

The colon provides a dramatic and somewhat underutilized way to bring a little spark to your writing. Beyond normal business correspondence (Dear Sir or Madam:), you can use the colon before quotations, formal statements and explanations. The colon enables you to highlight a semantic relationship–that is, a movement from a general statement to a specific clarification. The colon also provides a dramatic way to tease the reader’s curiosity:

  • As a modern ordeal by torture, litigation excels: It is exorbitantly expensive, agonizingly slow, and exquisitely designed to avoid any resemblance to fairness or justice.

You can also use the colon before an instruction or example:

  • An intelligent writer knows how to polish documents: revise the document countless times.

Although usage does differ, most stylists agree that you should not capitalize the first letter after the colon unless the colon is introducing a quotation or formal statement:

  • You’ll be surprised by what his former employees wrote in the character report: “His attitude toward his new associates was rude and pretentious.” This sentence can easily be revised:

Note that a colon must always follow an independent clause. You should never place a colon between a verb and its direct object.

Incorrect: Our choices are: rescind our offer, go ahead with our plans, try to renegotiate the deal.

Because the colon works as the equivalent to for example or such as, it would be redundant and incorrect to write

Incorrect: We have a number of options, such as: a, b, c.

Correct: We have three choices: a, b, c.

Use colons to introduce items in lists, detailed examples, or further information.

Use a colon to separate a complete sentence from a list (of three items or more) that follows.

Jennifer was everything he wanted in a wife: intelligent, funny, and sexy.

He knew the best way to win her love: cook dinner every night.

The students brought items from the supply list to class: paper, pens, and highlighters.

Colons used this way replace such as or for example. To use both words and colon are redundant—you need one or the other, but not both. Keep in mind that you only use a colon after a noun: you are giving more information about that person, place, or thing.

Use a colon to separate a complete sentence from a statement that explains or clarifies the first.

The college bookstore sells more than just textbooks: clothing and office supplies are also available for purchase there.

Use a colon to separate a complete sentence from a noun or noun phrase that further identifies or explains the subject.

The librarian’s primary interests drew him to the college library: love for books and a quest for knowledge.

Use colons to introduce quotes that are not being introduced in another way, such as with that.

The researcher reported on one of the consequences of homelessness: “Those who live on the street were found to be vulnerable to a variety of communicable diseases.”

Use colons to introduce block quotations, or quotes that go on for more than four lines of text.

Correct: The author claimed: “I didn’t intend to write the Great American Novel.”

Incorrect: The author claimed that: “I didn’t intend to write the Great American Novel.” Quotes introduced with that are considered embedded quotations, and they do not need to be introduced with a colon.

Use colons for ratios, time, and certain literary verses

The verdict of 3:2 was recorded at 5:00 pm while some cited John 3:16.

Here, 3:2 refers to the vote in a trial—three people voted one way, and two people voted the other way. 5:00 refers to the time that the event occurred. John 3:16 is a Bible verse that some people like to put on signs.

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