How to use colons with confidence

What is a colon?

A colon is a small and versatile punctuation mark. Or part of the large intestine. Despite having three doctors in my close family and consuming every medical drama that becomes available on Netflix, I know less about body parts than I would like to.

So let's talk about the punctuation mark, which allows writers to introduce elements that build on what went before, in the form of a list, an explanation, a noun phrase, a quote, or emphasis. There is always a connection between what sits on the left and right sides of the colon. Colons can also be used in expressions of time and to separate titles and subtitles.

How are colons used?

1. Colons introduce lists: both run-on lists and bulleted, displayed, or vertical lists

   
   

Example: run-on list

The UK is made up of four nations: England, Scotland, Wales, and Northern Ireland.

Example: bulleted/displayed/vertical list

The UK is made up of four nations:

England

Scotland

Wales

Northern Ireland

2. Colons introduce explanations

Example

The reason for her frustration was simple: she didn't trust AI.

3. Colons introduce nouns or noun phrases

   
   

Example

His goal was simple: world domination.

4. Colons introduce direct speech or quotations

   
   

Example

Referring to the man who would become her husband – William Shakespeare – Agnes said: "He's got more inside of him than any man I've met."

5. Colons connect two independent clauses, where the second reinforces or emphasises the first

Example

Hamnet is an emotional watch: there wasn't a dry eye in the cinema.

6. Colons are used in expressions of time

   
   

Example

She had to be home by 10:30 pm (22:30).

7. Colons separate a title from its subtitle

   
   

Example

Her favourite book was The Lord of the Rings: The Fellowship of the Ring.

A few things to remember about colons

1. A colon should not separate 'such as' or 'including' from what follows them (although bulleted lists allow more leniency with this)

Examples

❌ The spring is a season of wonderful things, including: new flowers, blossoms, and blue skies.

❌ The spring is a season of wonderful things, such as: new flowers, blossoms, and blue skies.

✅ The spring is a season of wonderful things, including the following: new flowers, blossoms, and blue skies.

✅ The spring is a season of wonderful things, such as new flowers, blossoms, and blue skies.

✅ The spring is a season of wonderful things: new flowers, blossoms, and blue skies.

2. UK English often uses a lowercase letter after a colon (apart from proper nouns), even when what follows is a complete sentence

Examples

✅ I cannot wait for the spring: the sun is far more likely to make an appearance.

✅ Her question was simple: when was she going to get out of there?

3. But you could use capitals in UK English if two or more sentences/questions follow the colon

   
   

Examples

✅ I cannot wait for the spring: The sun is always stronger. And the days are longer.

✅ She had a few questions: How would she get out of there? And when?

4. US English often capitalises the first word after a colon when it is part of a complete sentence

Example

✅ I cannot wait for the spring: The sun is far more likely to make an appearance. (CMOS18/APA)

5. And finally, semicolon or colon?

First, colons introduce lists, and semicolons (or commas) separate the items in a list.

Example

✅ She had too much to carry: lemons, oranges, and limes; chocolate, vegan marshmallows, and sweet biscuits; and a jar of expensive coffee.

And second, colons can introduce sentence fragments, and vice versa, while semicolons join two connected but independent clauses.

Example

✅ Bad Bunny is an amazing artist: talented, creative, and full of soul.

✅ Bad Bunny is an amazing artist; he deserves to win many awards.

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Did you find this post helpful?

Whether you’re working on a blog post, a business report, or an academic paper, small details like punctuation and word choice can make a big difference to your writing. If you found this post helpful, you’ll find more practical tips on grammar, punctuation, and writing in my other blogs.

Or get in touch if you would like me to worry about this – and other things – for you.