Parentheses, Brackets, and Braces

What’s the difference?

Bonnie Mills, Writing for
5-minute read
Episode #233

Square Brackets

Now it’s time to introduce our potentially misused friends: square brackets. Brackets, which are one long line short of a standing-up rectangle, appear on the keyboard to the right of the letter “p.” They seem less common than their parenthetical cousins, though you do sometimes see both punctuation marks within the same sentence. Use brackets in sentences where you want to put parentheses within parentheses. Since two parentheses in a row would be confusing, you bookend your parentheses with brackets. So, the order is opening parenthesis, opening bracket, closing bracket, closing parenthesis. For example, you would write “They are getting married (they love each other [of course!]).”*

According to Garner, square brackets also come in handy for subsequent authors and editors who want to “enclose comments, corrections, explanations, interpolations, notes, or translations that were not in the original text” (2).

If you are in a scholarly field, you may find yourself writing a paper and quoting an expert, and perhaps you discover you need to clarify what the expert said. Bill Walsh in Lapsing into a Comma (3) warns, “Bracketed material should clarify language, not replace it….” You shouldn’t alter what the original writer wrote, so use brackets around your clarification. For example, if the original quotation reads, “This enterprising paleontologist discovered a new species of plant eater,” you shouldn't change it to “[Bob Jones] discovered a new species of plant eater.” You’d have to quote the material this way: “This enterprising paleontologist [Bob Jones] discovered a new species of plant eater.” (Note also that you wouldn’t be allowed to use parentheses around the name you add, because it would seem—incorrectly—like an aside that appeared in the original text.)

Remember, though, that brackets differ from the three dots called an ellipsis, which you use when you are deleting extraneous words from a direct quotation. If you want to learn more about an ellipsis, see the recent Grammar Girl episode on ellipses.

Sometimes you might decide to start a sentence by quoting someone, but the quotation does not include a capital letter. If your work is informal or not overly formal, it is acceptable to just change the lowercase letter to a capital one. On the other hand, scholars who must be “rigorously accurate” (4) are required to use a set of brackets around the capital letter they are changing. For example, if the quoted word is “it,” with a lowercase “i,” and a rigorously accurate scholar wants the word “it” to start a sentence, she would have to write bracket-uppercase I-bracket-lowercase t: “[I]t.” [Note: the newest edition of the Chicago Manual of Style (17th) says it is usually not necessary to add the capital letter in brackets.]

The last place you are likely to encounter square brackets is around the Latin word “sic,” which means “thus.” You use it—in italics—when you’re quoting someone who has made an error, such as a misstatement of fact or a spelling mistake. You should use bracket-sic-bracket only when you need to aid readers (5); you don’t want to show off or seem pedantic by constantly pointing out others’ failings. Admittedly, though, we grammar types understand this urge to correct others.

Next: Braces {}


About the Author

Bonnie Mills, Writing for Grammar Girl

Bonnie Mills has been a copyeditor since 1996.