Colon — When to Use and Examples
What is a colon?
A colon is a punctuation mark that consists of two dots positioned one on top of the other (:). It indicates a pause to let the reader know important information will follow a full sentence.
The primary function of colons is to introduce quotations, explanations, examples, or lists. They can also appear after a salutation in a formal or business letter and separate a title and subtitle of books and articles.
When to use a colon
The following rules detail when and how to use colons:
Emphasis: Insert a colon after an independent clause to emphasize a phrase or single word at the end of a sentence.
After hours of debate, the family finally agreed on a name for their new dog: Max.
Lists: When a list of items is not part of the natural flow of a sentence, place a colon at the end of the independent clause.
Bulleted Lists: Use a colon to introduce a bulleted or numbered list.
Pack these items for the trip:
Independent Clauses: Place a colon at the end of an independent clause (complete sentence) if what proceeds explains or illustrates what is in the first part of the sentence. The first clause must be directly related to the second clause.
John was going to be late for work: his car's battery had died.
Time: Colons separate hours from minutes. There are no spaces before or after the colon.
3:30
Ratios: Separate ratios with a colon as a replacement for "to." There are no spaces before or after the colon.
2:3 (2 to 3)
Professional/Formal Correspondence: Colons often separate information in professional communication.
Titles/Subtitles: Use a colon to separate the main title from a subtitle.
2001: A Space Odyssey
Biblical References: When identifying a specific passage in the Bible, a colon separates chapter and verse. There are no spaces before or after the colon.
Genesis 1:7-9
Citations: Some style guides require a colon in citations and reference lists, but not all.
Colon Misuse: Do not use a colon to separate a verb or preposition from the object(s) in a sentence.
Verb
Incorrect: The items you need to pick up from the store are: milk, bread, and cheese.
Verb: are
Objects: milk, bread, and cheese
Preposition
Incorrect: After graduation, I want to go to: Dublin, Paris, and London.
Preposition: to
Objects: Dublin, Paris, and London
Semicolon vs. colon
The purpose of a colon is to indicate that the information to follow provides an example or explanation of what precedes it. However, the purpose of a semicolon is to separate closely connected independent clauses.
While both colons and semicolons can connect independent clauses, the primary use of the colon is to connect those clauses with a list or noun.
Semicolon: Jeremy had to pick up two things at the mall; he was concerned he wouldn’t be able to find a button-up shirt and tie.
Colon: Jeremy had to pick up two things at the mall: a button-up shirt and tie.
Colon examples
The following sentences incorporate the correct use of colons:
Emphasis
The lawyer looked at the faces of the jury and he knew the verdict they reached: not guilty.
Upon opening the door, she couldn't believe who was standing there: her long-lost brother.
After such a long day, Jody only wanted to see one thing: her family.
Lists
Before vacation, Emily still had to purchase three items: sunglasses, sandals, and shorts.
The teacher chose three students to represent the class: Mark, Anna, and Pat.
There are three main cloud types: cumulus, stratus, and cirrus.
Independent Clauses
Technically, a whale is not a fish: it's a mammal.
Dr. Lane's research was conclusive: there's no life on the moon.
After dinner, the children did something without being asked: they cleaned off the table.
Time
The musical starts promptly at 7:00.
I have a 4:00 job interview today.
When the clock strikes 12:00, a new year has begun.
Ratios
The ratio of red marbles to blue marbles is 4:5.
The ratio of junior varsity to varsity players was 15:10.
Our teacher asked us to simplify the ratio 30:15.
Professional/Formal Correspondence
Dear Mr. Oliver: I am writing to you regarding the job opening at your New York location.
PS: Don't forget the suntan lotion.
Titles/Subtitles
The title of his dissertation was Student Growth: The Benefits of Extracurricular Activities.
Look for the article titled "Space Race: The Cost of Landing on the Moon."
Lee's favorite Marvel movie is Captain America: The First Avenger.
Biblical References
A rather famous biblical passage is in Genesis 1:31.
Football fans would often hold up signs referencing John 3:16.