When and how to use parentheses vs. brackets

Parentheses and brackets: What’s the difference?

Both parentheses and brackets are used to set apart words or phrases within a sentence. Think of them as asides: they are digressions, adding additional information that otherwise clutter up a sentence if not isolated Parentheses ( ) are round, and brackets [ ] are squared off, and always come with opening and closing pairs. Learning these grammatical and writing essentials can make a world of difference in your communication.

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But while they can look and function similarly, they have different usages that have long been established in English grammar. Commonly, parentheses add extra information that could help the meaning of a sentence or passage, while brackets add text that is missing from an original quote. Read on to learn how to use parentheses, and how to use brackets, and when to use one over the other.

How to use parentheses

Parentheses add extra information that could clarify or add context.

Below is an example:

• When you are using parentheses (a singular is parenthesis), this is how you do it.

Is it important that the reader knows about the information in the middle of the sentence? Perhaps, but it’s not necessarily vital, nor does it change the meaning of the statement being made.

It’s important to make sure that the sentence is grammatically correct even if the parentheses are removed. Therefore, the below sentence won’t make any sense:

• We are (sweating in this 90-degree heat).

Because “we are” does not make for a complete sentence. Instead, the correct parentheses usage would read like this:

• We are sweating (in this 90-degree heat).

Other common ways to use parentheses

Parentheses are also used to define acronyms, either when expanding on or contracting an acronym. Both examples below are valid:

• The National Aeronautics and Space Administration (NASA)
• The FBI (Federal Bureau of Investigation)

The first time you write a parenthetical definition for an acronym, you’ve established it for the rest of the piece, and you can use the acronym from there without having to expand on it.

Parentheses are also used for citations in research papers, as recommended by the APA, Chicago, and MLA formats:

• Research performed on rhesus monkeys showed clear changes in demeanor (Gauss, 1996).

And parentheses can also add editorialization from the writer, which can be interjected in an op-ed as the writer’s voice speaking directly to the reader—the true use of an aside:

• The senator vowed that trickle-down economics would benefit everyone (haven’t we heard this before?).
• He had been lampooned in the press for his ridiculous hat (which I actually thought was kind of cool).

Parentheses also do the heavy lifting on more mundane grammatical tasks, such as introducing inline lists, making a word both singular and plural, or formatting time zones and area codes.

• (a) pizza, (b) breadsticks, or (c) chicken wings
• any question(s)
• 8:00pm (EST)
• (508) 555-1234

How to use brackets

In general language, brackets appear less frequently than parentheses, which can be why their usage can seem confusing. Brackets are used almost exclusively within quotations: they surround text that can enhance or continue a quotation from before. Take a look at the following example:

• “Alas, poor Yorick [who Hamlet knew as a child], I knew him, Horatio…”

This serves the purpose of a parentheses, but it’s nestled within a quote. Therefore, it is an explanation within an established text. It serves to explain and add context to the original quote, but it is not part of it.

Brackets can also be used to fill in the blanks. For example, if a quote has been truncated, you can use brackets to fill in additional context that can support the gist of the quote. This is especially useful for citing text where space is limited:

• Shawn said, “Steve had given [his ex-wife] Caitlin a gift.”

This is a direct quote, but the brackets interject with additional clarification. There is a lot of information that we have presumed to notice before, but these brackets only serve to reinforce it.

Lastly, brackets are commonly used in editorial commands, such as [sic], which is a quote-related command that says, the previous passage may be misspelled or grammatically incorrect, but it is being preserved in its original form as a way to add truth or authenticity to the quote. See the below example:

• The witness was recorded to have sent via email, “I dunno [sic] what else happened.”

While “dunno” is not grammatically correct, it is in the person’s voice, and will add authenticity to the work—without leading to the idea that the writer has made a grammatical error themselves. This is especially useful in reporting or nonfiction writing and adds a truth and dimension to the work.

When do you use a bracket over a parenthesis, or vice versa?

Use parentheses when adding information that might otherwise be ignored or superfluous. Use brackets with quotes. Whether there is existing text that is being cited, brackets serve as a

Sometimes, an aside will be nestled within another aside. Consider the following sentence:

• Yesterday she made the phone call [to the staffing agency (which she always hated to do)].

There are two asides to this: the writer is saying that she made a phone call, but more specifically, to a staffing agency, and even more specifically from that, that she always hated to do so. When stacking multiple asides on top of each other, it is always a bracket that surrounds a parenthesis. Here is another example:

• I went to Catholic school [at St. Mary’s, in central Massachusetts (which was a boring place to grow up)] and it changed my life.

Removing either or all of the asides will still make the sentence grammatically correct.

• I went to Catholic school (at St. Mary’s, in central Massachusetts) and it changed my life.
• I went to Catholic school, and it changed my life.

As you learn more about the finer points of grammatical and punctuation rules, your writing will not only grow in confidence, but you’ll also avoid some of the most common grammatical errors. Check out Microsoft 365 for more writing tips to round out the rest of your creative or professional writing life.