Colons are mainly used to introduce additions, modifications, and basic examples, including summaries, series, explanations or quotations.
Use a colon to introduce items in a series
1. Use a colon to introduce a series of items. Do not capitalize the first word following the colon unless it is a proper noun, as in the second example below, or unless the colon is followed by an independent clause.
- Katie enrolled in four classes this semester: algebra, philosophy, economics, and biology.
- Eric enrolled in three classes this semester: English literature, calculus, and history.
2. Do not use a colon inside an independent clause.
- Six ingredients used to make bread are: flour, eggs, butter, salt, yeast, water. (✗ incorrect)
- Six ingredients used to make bread are flour, eggs, butter, salt, yeast, water. (✓ correct)
Using a colon to introduce an ordered or bulleted list of items
Use a colon to introduce a bulleted or numbered list only if an independent clause precedes the colon. No capitalization or end punctuation is needed for list items unless the list item is a proper noun or an independent clause. Notice the capitalization of proper nouns below.
There are eight planets in our solar system:
You need six ingredients to make bread:
Use a colon to introduce explanatory text
In the example below, the dependent clause following the colon explains what is meant by “what he deserved” in the sentence preceding the colon.
- He got what he deserved: ten days in jail for public drunkenness.
Using a colon to introduce a quotation
Note in the example below that the quotation is an independent clause (complete sentence), which requires the first word following the colon to be capitalized.
- Deborah suggested a solution: “Screw the cap on tightly before you shake the milk jug.”
Use a colon to join independent clauses
A colon may link independent clauses when the second clause is directly related to the first clause and explains some aspect of the first. In the first example below, the sentence following the colon explains what is meant by “valuable lesson” in the first sentence.
- Timothy learned a valuable lesson about fishing: You must speak quietly, or you will scare away the fish.
- There is no denying the evidence: Global warming has already begun.
Colons have several other non-grammatical uses:
- Revelation 1:1
- John 3:16
- Lamott, Anne. Bird by Bird: Some Instructions on Writing and Life. Anchor Books, 1995.
Formal business letter salutation
- Dear Sir:
- To Whom It May Concern:
Attention line in address
- Attention: Jim Jones
- Peoples Temple
- 1978 Kool-Aid Rd.
- Jonestown, Guyana
Title and subtitle
- Roots: The Saga of an American Family
- The Book of Joy: Lasting Happiness in a Changing World
- We get out of class at 3:30 p.m.
- I get up at 6:00 AM every morning.
- A ratio of 6:2 is equal to the ratio 3:1.