Punctuation 101: How To Use Brackets

Brackets, also known as parentheses, separate a word or phrase from the rest of a sentence. The most commonly used are round brackets ( ) and square brackets [ ]. Brackets are always used in pairs and their function is to add information without fragmenting the main sentence and the sentence itself remains whole if the words in the brackets are removed.

Round Brackets ( )

Unlike square brackets, the information enclosed in round brackets remains a part of the sentence, but is not the most important aspect. Here’s an example:

When he saw Sally (a girl he used to go to school with) in the café, he could not believe his eyes.

As you can see, the information in the brackets is not vital to the sentence’s meaning or structure. In this way, the round brackets can be likened to a minor interruption in the normal flow of the writing.

In many cases, a pair of commas or dashes can be used in much the same way as round brackets:

When he saw Sally, a girl he used to go to school with, in the café, he could not believe his eyes.
When he saw Sally – a girl he used to go to school with – in the café, he could not believe his eyes.

However, these are only used when the secondary piece of information (i.e. the man went to school with Sally) has a stronger link to the main sentence.

It is best to not have long brackets as this can make your writing appear clumsy. For that reason, use them as sparingly as possible and also take care when closing a bracket at the end of a sentence, as this can cause punctuation errors. Unless the whole sentence is in brackets, the full stop is always outside the second bracket:

The train will call at Gillingham (Kent) and Rainham (Kent).

Square Brackets [ ]

In contrast to round brackets, square brackets are commonly used to enclose text that is included to explain something but is not a direct part of the sentence:

I [pronoun] love [verb] dark [adjective] chocolate [noun].

“Pronoun”, “verb”, “adjective” and “noun” are explanatory words but are not a part of the sentence “I love dark chocolate” and so need to be distinguished clearly from the words in the sentence by the use of square brackets.

Another example of the use of square brackets is the insertion of words into a quotation that are not actually a part of the quote but are included as a means of explanation:

“According to John, he said he ‘couldn’t believe it when he saw her [Sally] as they used to go to school together.’ He was very surprised to see her after all these years.”

The square brackets provide information but are not a direct part of the quotation. As with the round brackets, it is best to use square brackets in moderation.