Colons

​​In a nutshell

A colon is a punctuation mark that looks like two full stops on top of each other (:). It is a very useful grammatical tool that can help you introduce lists, quotations, explanations or extra information as well as separate closely related clauses.

Using colons

The colon (:) and semi-colon (;) aA colre similar-looking punctuation marks but serve very different purposes. They should not be used interchangeably, so pay attention. Here are four rules of the colon:

Rule 1

A colon can be used to introduce a list. It should always follow a main clause (complete sentence) before introducing the list.

Example

This is what you need to bake a cake: flour, butter, eggs, sugar, salt, milk and baking soda.

NOT

You need: flour, butter, eggs, sugar, salt, milk and baking soda.

Rule 2

A colon can also be used to introduce a quotation. This can be really useful, especially when you want to quote something from a text (in essay writing etc.). Just as with lists, the colon should always follow a main clause.

Example

I like the famous saying by Mahatma Gandhi: "You must be the change you wish to see in the world".

Rule 3

A colon can even be used to introduce extra information or an explanation of a point you've just made. Again, the colon should always follow a main clause. The phrase that comes after the colon explains what came before it. To help you understand this a little more, replace the colon with the word, 'because'.

Example

Colons are very useful: they can help to introduce extra information.

Colons are very useful because they can help to introduce extra information.

Rule 4

Lastly, colons can be used to separate two main clauses that are closely connected. You could use a full stop to separate them, but a colon helps emphasise the connection between the two main clauses.

Example

​Eating more vegetables is good for your health. There is no arguing with this fact.
Eating more vegetables is good for your health: there is no arguing with this fact.

Note: you might be thinking, "isn't this exactly what a semi-colon does?" and you'd be somewhat correct; however, a semi-colon is used when you want to show a really close relationship between two main clauses (too closely related to be separated by a full stop).