Chapter 3-9: Parentheses, Parenthetical Expressions, and Brackets
Definition of Parentheses
The word parenthesis (written as parentheses in the plural form) means different things to different people depending on the region they come from.
In the United States, this word usually means round brackets, like this: ()
In the United Kingdom, this word can refer to any type of parenthetical punctuation such as brackets, commas, and dashes.
In Canada, people are caught somewhere between these two ideas.
This page aims to make everyone happy, so it will discuss how parenthetical expressions can be made using punctuation, and it will also discuss the various types of brackets that exist.
Parenthetical Expressions
Parenthetical expressions are created by using punctuation to offset text.
Dictionary.com defines a parenthesis as "a qualifying, explanatory, or appositive word, phrase, clause, or sentence that interrupts a syntactic construction without otherwise affecting it, having often a characteristic intonation and indicated in writing by commas, parentheses (brackets), or dashes."
In simpler terms, parentheses allow writers to provide additional information or afterthoughts. Some people also call this extra information, extraneous information, and asides:
Joe Biden, who was the president at the time, declared war on Australia.
Trifle (not to be confused with "truffles") is a delicious dessert.
My sister—who was a gold medallist in the 2026 Olympics—had an asthma attack today.
Choosing a Punctuation Type
Some people argue that specific types of punctuation should be used for particular scenarios. Generally, all three types of punctuation—commas, parentheses (brackets), or dashes—can be interchanged.
Using different types of punctuation can reduce confusion. For example, which of the following sentences is easier to read?
To make French lime sorbet, you will need water, sugar, lime juice, not the kind from a bottle, and zest.
To make French lime sorbet, you will need water, sugar, lime juice (not the kind from a bottle) and zest.
The second sentence is easier to understand. Readers understand that "not the kind from a bottle" refers to the type of "lime juice" that should be used. The first sentence is more confusing.
Using different types of punctuation can inject variety into a paragraph or a long text. Imagine reading a 10-page text where the author only used round brackets () to provide additional information to readers. Readers prefer a bit of variety when they read. Alternating between the three types of parenthetical punctuation offers more variety.
Effects Created by Different Types of Punctuation
Alternating between the various types of punctuation to create a parenthetical aside may provide variety. Still, authors should be aware of the following nuances associated with each kind of punctuation:
Commas (,): people are used to seeing commas in sentences, so this form of punctuation doesn't call much attention to itself. However, as discussed above, it can become confusing if there are too many commas in a sentence being used for different purposes.
Parentheses (()): unlike commas, parentheses clearly communicate to readers that what is within them is an aside. They stick out clearly. However, using parentheses on official correspondence can be interpreted by readers as being too informal.
Dashes (—): like parentheses, dashes stick out clearly, although some people feel that they are a little bare.
Types of Brackets
Four different types of brackets can be used in writing and they come in pairs:
Parentheses / Round Brackets
As discussed above, parenthesis can be used to enclose extra information. But, they can also be used to indicate that a plural might be possible:
Place the insect(s) in a bag.
Box Brackets / Square Brackets
These brackets are used to indicate that the author has inserted words or clarifying information into another author's text:
According to our Prime Minister, "All [provinces] succeed."
Braces / Curly Brackets
These brackets list items and choices. They are almost never used:
Choose a car {Audi, BMW, Ford, Mercedes} for your avatar.
Angle Brackets / Chevrons
These brackets are also almost never used. They're usually used in peculiar circumstances. They can be used to express something being said in a foreign language, an action, or a narrator's thoughts:
«Sortez d'ici!» the museum guard said.
«In a meeting.» (a message seen on a chat interface)
"Good morning," Sandy said. «I hate mornings,» she thought.
External Resources
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