When to Use a Colon (:) | Rules, Guide & Examples
A colon (:) can be used to introduce words, phrases, lists of items, explanations, and elaborations. It can also be used to introduce a quotation.
In general, you can think of colons as saying ‘what comes next explains what came before’. A colon must be preceded by an independent clause: a fully formed thought that could stand as a sentence on its own.
Introducing a word or phrase
Colons can be used to add emphasis when introducing single words or phrases.
- She asked for only one thing: understanding.
- The researchers found something unexpected: a dramatically lowered risk of heart disease.
When using a colon this way, always make sure the text before the comma is an independent clause that could stand as a complete sentence on its own.
- The first step towards a healthier lifestyle is: a good night’s sleep.
- The first step towards a healthier lifestyle is simple: a good night’s sleep.
Introducing a list
A colon can be used to introduce a list when the introductory phrase is an independent clause.
- My garden has four kinds of flowers: daffodils, tulips, roses, and chrysanthemums.
However, a colon is not always needed to introduce a list. Make sure not to use a colon after the verbs ‘be’ or ‘include’.
- The four kinds of flowers in my garden are: daffodils, tulips, roses, and chrysanthemums.
- The four kinds of flowers in my garden are daffodils, tulips, roses, and chrysanthemums.
The first sentence is incorrect because the part before the colon is not an independent clause – it doesn’t form a full sentence on its own. The word ‘are’ already signals that what will follow is connected to what comes before, so no colon is needed to connect the list to its introduction.
The table below shows two ways of fixing this error: removing the colon or rewriting the text that precedes it.
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| Our holiday itinerary in London includes: taking a walk along the canal, seeing several musicals in the theater, and enjoying a fancy meal at a restaurant. | Our holiday itinerary in London includes a variety of activities: taking a walk along the canal, seeing several musicals in the theater, and enjoying a fancy meal at a restaurant. | Our holiday itinerary in London includes taking a walk along the canal, seeing several musicals in the theater, and enjoying a fancy meal at a restaurant. |
| The three elements comprising formaldehyde are: carbon, oxygen and hydrogen. | Formaldehyde is comprised of three elements: carbon, oxygen and hydrogen. | The three elements comprising formaldehyde are carbon, oxygen and hydrogen. |
| This study will collect and compare data from: Nigeria, South Africa, and Kenya. | This study will collect and compare data from three countries: Nigeria, South Africa, and Kenya. | This study will collect and compare data from Nigeria, South Africa, and Kenya. |
Introducing an explanation or elaboration
A colon can connect two independent clauses when the second clause explains, elaborates on, or follows from the first.
- Though some of my colleagues disagree, I stand by my opinion: catering to current market trends alone won’t ensure the long-term success of the company.
As always, when using a colon to introduce an explanation, make sure that the text before the colon could stand as a complete sentence.
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| To caramelise the onion: sauté it on low heat for at least fifteen minutes, stirring occasionally. | First, caramelise the onion: sauté it on low heat for at least fifteen minutes, stirring occasionally. | To caramelise the onion, sauté it on low heat for at least fifteen minutes, stirring occasionally. |
| The research concluded that: aerobic exercise results in improved mood and appetite in adults of all age groups. | The research was conclusive: aerobic exercise results in improved mood and appetite in adults of all age groups. | The research concluded that aerobic exercise results in improved mood and appetite in adults of all age groups. |
Introducing a quotation
A colon can also be used to introduce a quotation.
- The teacher shouted at the students: ‘Don’t talk when I am speaking!’
- It was all over the news: ‘Prime Minister resigns in tears.’
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Luo, A. (2023, April 06). When to Use a Colon (:) | Rules, Guide & Examples. Scribbr. Retrieved 9 December 2024, from https://www.scribbr.co.uk/english-language/colon/
