Using colons: Rules, tips and examples

The colon (:) is one of the punctuation marks in the English, which gives the opportunity to structure the text in sentences and is often used after explaining or completing the main sentence, before a list or before quotations.  This mark may seem simple, but using it correctly in the appropriate contexts requires knowing specific rules. In this article, we’ll look at the rules for using the colon and provide concrete examples for better understanding.

Rules for using colons

Before a list

Colons are commonly used to introduce a list. It’s important that the text before the colon forms a complete sentence.

• Examples:
  • I need to buy several items: bread, milk, eggs, and butter.
  • Our picnic basket was filled with delicious treats: sandwiches, fruit salads, cheese platter, and sparkling drinks.

After an introductory phrase, for explanations or quotes

When you want to introduce a quote, explanation, guidance, or deeper description, use a colon after the introductory phrase to elaborate on the first part of the sentence.

• Examples:
  • My grandmother always said: “A stitch in time saves nine.”
  • The teacher said: “Homework is due tomorrow.”

Between independent clauses

You can use a colon between two complete sentences when the second sentence explains or elaborates on the first.

• Example:
  • I didn’t get the job: I lacked the required experience.

For explanations or clarifications

Use a colon when the first part of the sentence is the main idea, and the second part explains or clarifies it.

• Example:
  • She was upset: her dog had run away.

In time notations, titles, and ratios

Colons are also used in time notations and to separate chapters and titles in documents.

• Examples:
  • Time: 5:30 PM
  • Title: Smith: An Ecological Perspective
  • Page Numbers: The book is on pages 45:67.
  • Ratios: The ratio is 2:1.

When not to use colons

The colon is an important punctuation symbol in English, but its use is limited to certain rules. Let’s consider the main instances when using a colon is not recommended.

After a verb or preposition

A colon should not be used immediately after a verb or preposition that precedes a list. Using a colon in this context usually looks out of place and can cause confusion.

• Incorrect: I want to visit the cities like: London, Paris, and Tokyo.
• Correct: I want to visit the cities like London, Paris, and Tokyo.

After a phrase that is not a complete sentence

A colon should only be used when the text before it forms a complete, standalone sentence.

• Incorrect: My favorite fruits are: apples, oranges, and bananas.
• Correct: My favorite fruits are apples, oranges, and bananas.

When using with other punctuation marks

A colon should not be used in conjunction with other punctuation marks, such as a comma or period.

• Incorrect: He is responsible for cooking, cleaning, etc.: chores that take up much of his time.
• Correct: He is responsible for cooking, cleaning, etc., chores that take up much of his time.

In headings for explanations

Often using a colon in headings looks out of place or too informal.

• Incorrect: How to Fix: a Leaky Faucet
• Correct: How to Fix a Leaky Faucet

Use these guidelines to avoid common mistakes when using colons and to make your writing more readable and grammatically correct.

Useful tips for using colons

• Make sure a complete sentence precedes the colon: It is incorrect to use a colon after an incomplete phrase.
• Do not overuse colons: This punctuation mark has specific use cases. Excessive or incorrect use of colons can make text harder to read.
• Carefully choose instances for lists: First, indicate that a list is coming, then use a colon to introduce it.

Therefore, the colon in English helps organize information, introduce quotes, explanations, and lists. Remember these rules and use colons correctly to improve your writing.