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What Are Colons? (with Examples)

A colon (:) is a common punctuation mark used:
  • To extend a sentence with an appositive (a renaming of something previously mentioned). For example:
    • He attributed his success to one factor: luck.
  • To mark the end of an introduction (including before quotations). For example:
    • The inspection highlighted the following issues: too many coffee breaks, insufficient leadership, and too much non-work-related internet usage.
    • Philosopher Rene Descartes said: "I think; therefore, I am."
  • To separate elements in times, ratios, titles, and reference numbers. For example:
    • Arrange a meeting for 09:30 to discuss ways to improve the 1:4 ratio.

How Colons Are Used

Here is a quick overview on how colons are used:

(1) With an appositive at the end of a sentence. You can use a colon to expand on something previously mentioned in the sentence. (The words after the colon are called an appositive.) For example:
  • His influence is obvious in two buildings: the local church and pavilion.
  • (In this example, "the local church and pavilion" is the appositive of "two buildings," i.e., it's a renaming of "two buildings.")
Read more about using colons to extend a sentence.
Read more about appositives.

(2) After an introduction. You can use a colon with an introduction. For example:
  • The following were absent: Charles, Smith, Wainwright, and Dodds.
This includes introductions to quotations. For example: Read more about colons used for introductions.
Read about colons used with bullet points.

(3) In references, ratios, times, and titles. A colon can be used as a separator in references, ratios, times, and titles. For example:
  • Read Matthew 2:1 before 07:30.
  • (Here, there is a colon in a reference and a time.)
  • The ratio is 6:1 in Nottingham.
  • (The colon is in a ratio.)
  • "Grammar Rules: Writing with Military Precision" is the book of
  • (The colon is in a title. )
Read more about colons used in references, times, and titles.

Other Punctuation Marks

Here is a slider with lessons to the other punctuation marks:

Why Should I Care about Colons?

Understanding how to use colons is a great tool to have in your writing kit. Using a colon to introduce an appositive at the end of a sentence is particularly useful for emphasizing an idea.

Here is the biggest error related to colons.

(Serious Error) Don't use a semicolon for an introduction.

A colon (often called a full colon) is used to introduce something. Do not use a semicolon (;) for this. This is quite a common error. For example:
  • The following were absent; Charles, Smith, Wainwright, and Dodds.
Here is another example featuring bullet points:
The inspection highlighted the following issues;
  • Too many coffee breaks.
  • insufficient leadership.
  • Too much non-work-related internet usage.

Read our main page about using colons.
Ready for the Test?
Here is a confirmatory test for this lesson.

This test can also be:
  • Edited (i.e., you can delete questions and play with the order of the questions).
  • Printed to create a handout.
  • Sent electronically to friends or students.

See Also

What is punctuation? What is an appositive? Colons to extend a sentence Colons for introductions Colons with bullet points Writing parallel lists Colons with references, times, and titles Colons with quotations Glossary of grammatical terms