Colons have several uses in English, often separating content or introducing information. We also use colons to designate time, show rations, and depict dialogue in plays and scripts.

Terms You Need to Know When Using Colons

MAIN CLAUSE (INDEPENDENT CLAUSE): A main clause is a phrase including a subject and a verb that expresses a complete thought. It is a complete sentence and is sometimes called an independent clause.

SALUTATION: A salutation is a greeting at the beginning of a letter. For example, you may write “Dear Mom,” at the beginning of a letter.

RATIO: A ratio is a comparison between two numerical values. A ratio shows the relationship that exists between pieces of information, such as the number of women to men in a room.

DIALOGUE: Dialogue is conversation between people. Within the context of a novel, dialogue is what characters say to one another.

7 Ways to Use Colons

Expand or Clarify a Main Clause
Introduce a List
Follow a Salutation in a Formal Letter
Separate Titles & Subtitles
Designate Time
Show a Ratio
Show Dialogue in a Play

1. Expand or Clarify a Main Clause

DESCRIPTION
A main clause is a phrase including a subject and a verb that expresses a complete thought. It is a complete sentence and sometimes called an independent clause. At times, you’ll want to expand a main clause with a dependent clause (incomplete thought.) You can use a colon to do this!

APPLICATION
To expand or clarify a main clause using a colon, place a colon after the main clause then add the information that expands or qualifies the main clause.

EXAMPLES

I have two favorite pastimes: reading and binge-watching TV shows.
- (In this sentence, the information after the colon expands on what my favorite pastimes are.)

My least favorite colors are as follows: chartreuse, burnt sienna, and sepia.
- (In this sentence, the information after the colon expands on what my least favorite colors are. Note that the colon does not come after the verb “are.”)

NOTE
Colons must come after a main, independent clause. Never use a colon after an incomplete thought or dependent clause.

2. Introduce a List

DESCRIPTION
If you have a main clause (complete sentence) that you want to expand by including a list of items, use the colon to identify to the reader that a list is coming.

APPLICATION
To introduce a list after a main clause, simply place the colon immediately following the list. Be sure that your main clause is, indeed, a complete sentence; don’t start a list after a verb like “are” or “is.”

EXAMPLE

Three people come to mind when you say the last name “Bacon”: Francis Bacon, the English philosopher; Yehuda Bacon, the Israeli Artist; and Kevin Bacon, that dude that’s within six degrees of anyone in Hollywood.
- (In this sentence, the list starts after the reader uses a complete thought. The sentence could technically end without the list and still be grammatically correct.)

NOTE
Colons must come after a main (independent) clause. Never use a colon after an incomplete thought.

3. Follow a Salutation in a Formal Letter

DESCRIPTION
A salutation is a greeting at the beginning of a letter. In a formal letter for business use, a colon is used to follow the salutation instead of a comma.

APPLICATION
To use a colon to follow the salutation in a formal letter, put the colon immediately following the salutation message.

EXAMPLE

Hello, Dr. Johnson:
(In this salutation, a colon is used to follow the salutation. This gives the appearance of professionalism and is more formal than using a comma would be.)

4. Designate Time

DESCRIPTION
A colon can be used to designate time. It is a common written form of telling time and is used in digital formats.

APPLICATION
To designate time, place the colon after the hour and before the minute.

EXAMPLE

My plane to Heathrow Airport leaves at 9:15 p.m.
(In this sentence, the colon is used to designate time by separating the hour from the minute.)

5. Separate Titles & Subtitles

DESCRIPTION
In writing headings and other situations, you may need to separate titles and subtitles (or headings and subheadings). To do this, use a colon.

APPLICATION
To separate a title and subtitle, place the colon immediately following the main title or heading.

EXAMPLE

If Maya were to write a short story, she would call it “Read, Write, Study: A Student’s Guide to College Life.”
(In this sentence, the colon separates the main title from the subtitle.)

6. Show a Ratio

DESCRIPTION
A ratio is a comparison between two numerical values. A ratio shows the relationship that exists between pieces of information, such as the number of women to men in a room.

APPLICATION
To use a colon to show a ratio, place the colon in between the significant numbers to simplify writing the ratio.

EXAMPLE

Stefani says that Alexander Hamilton would have had a 3:1 chance of beating Abraham Lincoln in an arm wrestling match.
(In this sentence, the ratio would be read “three to one.” The colon takes the place of “to.”)

7. Show Dialogue in a Play

DESCRIPTION
Dialogue is a conversation between people. In a play, dialogue is written in a specific format that uses a colon.

APPLICATION
To show dialogue in a play, put a colon after the character’s name to show that the following lines belong to that character.

EXAMPLE

Alisa: But I have nothing to wear that is good enough for meeting celebrities.
Andrea: I’m sure we can figure something out.
(In these lines, names of the speaker are written before the spoken dialogue, with a colon after the name.)