The Use of Brackets and Braces in Written English

Like all other punctuation marks, brackets and braces clarify written language by separating additional information from the main clause of a sentence. Brackets and braces perform seven basic functions in written English.

1. Use brackets to provide clarification within quotation marks. For example:

• According to a recent study on Internet usage, college students are "more likely to use it [the Internet] to find sources than academic journals."
• My mom said, "She [my little sister] cannot use the car on Saturday."
• And I quote, "You [new students] must attend at least one orientation session."

2. Use brackets to enclose parenthetical information inside of parenthetical information. For example:

• The author (Andrew Jones [1922-1978] was also an illustrator) won numerous awards for his writing.
• Summaries of all articles (including the article on phrasal verbs [verb-particle constructions]) must be written before the next class.
• (Mary Smith [the mother] bestowed a most unusual name on her daughter.)

For more information about the uses of parentheses, please see The Use of Dashes and Parentheses in Written English.

3. Use brackets around the abbreviated Latin expression [sic] meaning "thus" to indicate errors in quotations. For example:

• The President declared, "Our country is more great [sic] than our enemies."
• As the woman wrote, "The situation is much to [sic] dangerous to handle without help."
• "A journey of a thousand mile [sic] starts with a single step."

4. Use brackets to indicate revisions in quotations. For example:

• "They indicate strong emotion." "[Exclamation marks] indicate strong emotion."
• "But they also do other jobs..." "But [quotation marks] also do other jobs..."
• "They tell readers when to pause..." "[Commas] tell readers when to pause..."

5. Use brackets to enclose information about word origin. For example:

• dictionary [L.]
• grammar [OF.]
• strategic [F.]

6. Use braces to denote numeric sets. For example:

• {1, 1, 2, 3, 5, 8, 13}
• {2, 4, 6, 8, 10}
• {1, 2, 3}

7. Use braces to indicate sets of equal and independent choices. For example:

• Choose your favorite animal {dog, cat, bird} to feed a treat.
• After selecting your main dish {beef, chicken, pork, fish}, choose a vegetable.
• Choose a wine {white, rose, red} or a juice {apple, grape, orange}.

Braces are not commonly used in formal writing.

The accompanying printable reference sheet of the rules for using braces and brackets in English is available for download at The Use of Brackets and Braces in Written English Reference Sheet.