The Difference between Round and Square Brackets
The Quick AnswerRound brackets ( ) are used to insert additional information.
Round brackets can also be used to show that something could be singular or plural, e.g., Remove the pin(s) from the leg.
When round brackets are used to insert information at the end of a sentence, the end punctuation of the sentence is placed outside the bracket. For example:
- All the crew survived (even the dog).
- All the crew survived. (Even the dog survived.)
- All the crew (The crew was four men and a dog) survived.
Round Brackets for Additional InformationRound brackets are used to insert additional information in text. If you were to remove the brackets and the information inside, the text would still work. For example:
- Set in the 17th century, The Three Musketeers ("Les Trois Mousquetaires" in French) is a novel by Alexandre Dumas.
- Although they are relatively common off Australia, California, South Africa and Mexico, great white sharks usually inhabit coastal waters where the water temperature ranges 12-24 degrees Celsius. They generally hunt by detecting the electrical fields (They can detect less than one billionth of a volt.) emitted by the movements of their prey.
Round Brackets to Denote Singular or PluralFor brevity, round brackets can be used to show that a word could be either singular or plural. For example:
- Please write the name(s) of your guest(s) in the section below.
- Ensure the rod(s) is(are) aligned with the top section.
Square Brackets to Make the Text ClearerSquare brackets are used to add information that explains the text it follows. (The information is usually added by someone other than the original author.) For example:
- Hedy Lamarr once said: "Most people save all their lives and leave it [their money] to somebody else."
- "It [electricity] is really just organized lightning."
Square Brackets to Modify the Original TextOften, square brackets are used to replace text in a quote to make the quote clearer for the reader. For example:
- Hedy Lamarr once said: "Most people save all their lives and leave [their money] to somebody else."
- Alice Cooper famously said that "from the moment [he] leave[s] [his] house or hotel room, the public owns [him]."
Square Brackets: [sic]The term "[sic]" is used to show that the word it follows featured in the original text. Often, "[sic]" is used to indicate that a grammar error in the text was written by the original author. For example:
- The minister believed that his statement was "appropriate and did not undermine the moral [sic] of our
(should be "morale" not "moral")
- Your demand for a "full compliment [sic] of men" cannot be met at this time. (should be "complement" not "compliment")
Square Brackets: [...]Ellipsis is used to show text omitted from a quote. Ellipsis is usually written "..." or "[...]". For example:
- It's no small irony that the government [...] ends up promoting precisely that which they would most like to repress.
(The ellipsis replaces "inevitably and invariably".)
- Andy Warhol is the only genius...with an IQ of 60. (The ellipsis replaces the words "I've ever known" in this Gore Vidal quote.)