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Punctuating sentences

What is a sentence?

A sentence is a group of words that makes complete sense.

'She is running late.' This is a sentence.

'She is' isn't a complete sentence unless it is an answer to a question. (Is she running late? She is.)

Sentences can contain one statement:

'I fed the dog.'

or more than one statement:

'I fed the dog and then I went to the pet shop to buy more dog food.'

The second sentence covers three things:

  • feeding the dog;
  • going to the pet shop; and
  • buying dog food.

Try to have no more than two or three statements in a sentence.

Most sentences end with a full stop, but they can also end with a question mark or an exclamation mark.

Question mark

We use question marks at the end of direct questions:

'Have you fed the dog?' but not after indirect questions:

'She asked him if he had fed the dog.'

Try to make sure the question you are asking is clearly set out for your reader. It's easy to lose a question in the middle of lots of information, especially in an email. Then people wonder why they don't get a reply to their question!

Exclamation mark

An exclamation mark indicates something you would normally say loudly or strongly in speech.

'I told you not to feed that dog!'

It often demonstrates emotions such as anger, irritation or surprise. For this reason, exclamation marks are not used very much in business writing.

Other punctuation marks, such as commas, semicolons and colons, appear within sentences.


A comma is most commonly used to indicate where there would be a natural pause in speech.

'It was a tiring day, so tiring he fell asleep on the train and missed his stop.'

A comma can also be used to separate items in a list.

'I bought bread, cheese, olives and white wine.'

Sometimes we use a pair of commas, in the same way we use brackets, to separate parts of a sentence.

'I bought some olives, which we didn't eat, when I went shopping last week.'


A semicolon is a stronger break than a comma, but not as much as a full stop. We use semicolons to separate two closely linked sentences.

'They'd love to move house; it's just so difficult to sell right now.'

We can also use a semicolon to separate items in a list when we use bullet points.

'We aim to:

  • listen to your views;
  • investigate any concerns you have; and
  • provide a full response within 10 working days.'


A colon can act as a break in a sentence when we expect something to follow.

'Only four contestants remained: Louise, Jack, Michael and Ruby.' In business writing, we most commonly use colons to introduce lists.

'Please send us:

  • your filled-in application form;
  • proof of your identity; and
  • your last five bank statements.'

Sentence length

Try to aim for no more than 15 to 20 words in a sentence. Remember that no matter how many commas, semicolons and colons you put in, long sentences can be confusing.


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