A colon introduces something: a list, a quotation, or a second sentence that explains the first. In formal letters, it can also follow the salutation. Do not put a colon between a verb and the list that follows it, and do not use one where a semicolon belongs.
Punctuation rules are the ones people most often ignore or overlook when they check their spelling and grammar. Here are the rules for the colon.
When and how to use the colon
Colons differ from semicolons in meaning, so you should not use the two interchangeably. A semicolon links two independent sentences, while a colon carries the meaning of "that is to say".
Use a colon in these cases:
- to introduce a list of items
- to introduce direct speech or a quotation
- after the salutation in a formal letter or email
- to link two independent sentences when the second one explains or expands the first
Before a list
A colon introduces a single item or a list of items:
There was only one thing left to do: apologize.
If you go to the store, we need the following: bread, eggs, and cling wrap.
Before direct speech
In literary and fictional work, a colon can introduce direct speech. A comma is more usual there, though, and many writers keep the colon for longer or more formal quotations:
The sign on the door read: "Back in five minutes."
After the salutation
In an informal letter or email, a comma (or nothing at all) after the salutation is fine. Formal and business mail is different: there, and in American English especially, a colon is the usual choice:
Dear Mr. Smith:
Dear Sir or Madam:
Read more about greetings in business mail.
Between two sentences
In general, the colon and the semicolon cannot replace each other, but there is one exception. Two independent clauses are usually linked by a semicolon. When the second clause illustrates, extends, explains, or paraphrases the first one, you can use a colon instead:
She had it coming to her: you do not pull a dog's tail.
When not to use a colon
Do not use a colon:
- between a verb and the list that follows it
- in place of a semicolon when the second clause does not extend, explain, or illustrate the first one
When a verb introduces a list, the list is part of the sentence, so it needs no colon:
- Incorrect: I need: more time, a proper workspace, and more sleep.
- Correct: I need more time, a proper workspace, and more sleep.
Apart from the case above, a colon does not replace a semicolon:
- Incorrect: We can go to the beach later: however, I think the weather will change soon.
- Correct: We can go to the beach later; however, I think the weather will change soon.
Other rules for the colon
A few more rules apply when you use a colon. Some are fixed; others depend on your preference, the style guide you follow, or the context.
Capitalization
Should the first word after a colon start with a capital letter? It depends:
| After the colon | Capital letter? |
|---|---|
| A list of items (unless the first is a proper noun) | No |
| One complete sentence | No |
| Direct speech or a quoted sentence | Yes |
| Two or more complete sentences | Yes |
| The items of a bulleted or numbered list | Your choice, but be consistent |
These rules follow the Chicago Manual of Style. Other guides, such as AP and APA style, capitalize any complete sentence after a colon, so follow the guide you are asked to use. The rules of capitalization covers capital letters in general.
Other punctuation
How do you end a sentence or a list that contains or follows a colon? In a normal sentence, use the usual closing punctuation mark.
In a bulleted or numbered list, punctuation at the end of each item is optional, even when the item is a sentence or a clause. Depending on your preference, or on what your editor, boss, or client asks for, you can add commas and periods or leave them out. The only real rule is to be consistent.
Indentation
This mainly concerns longer quotations. When a long quotation follows a colon, many authors and editors set it off as an indented block instead of putting it in quotation marks. At the start of The Restaurant at the End of the Universe, the second book of his Hitchhiker's Guide to the Galaxy series, Douglas Adams wrote:
In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move.
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