Round brackets are called parentheses in American English but referred to simply as brackets in British English. In American English, the term brackets generally refers to square brackets. The only major difference in how brackets are used in American and British styles is in the use of brackets within brackets: in American writing, square brackets are used within parentheses (square within round brackets [like this]), while the British use round within round brackets (nested parentheses (like this)).
Terminology: Brackets or parentheses?
Round brackets ( ) are called parentheses in American English but known simply as brackets in British English. Regardless of this difference in terminology, they are used the same way: to set off explanatory information from surrounding text.
- An erupting volcano can cause other disasters (earthquakes, tsunamis, and rockfalls).
- We organize and book your entire trip for you (hotels, flights, taxis, etc.).
- Marine mammals (like dolphins and porpoises) are vulnerable to accidental capture.
- For an extra million dollars, you can drive the car yourself. (Newer models come with an optional self-drive feature.)
- Unidentified floating devices (UFDs) have been sighted this morning off the coast of Nusquam.
- The cat (or was it a ghost?) broke the vase.
- My friend Anita (the one I was telling you about last week) has won the award.
In American English, the term brackets is generally used to mean square brackets [ ]. In both British and American styles, square brackets enclose information (like an editorial comment or clarification) added to original text.
- They [the Durandians] landed on Earth on May 22, 2072.
- The mayor announced, “These two towns [Nusquam and Pouthena] are now connected by rail.”
- When she was nine, she wrote The Tree Freinds [sic].
Brackets within brackets
In American writing, square brackets are used within parentheses as brackets within brackets (to enclose parenthetical content that appears within text already in parentheses). In British writing, round brackets are used within round brackets.
- American: Geckos can cling to pretty much any surface except Teflon (see The Little Book of Lizards ).
British: Geckos can cling to pretty much any surface except Teflon (see The Little Book of Lizards (2017)).
- American: It was the warmest July in a hundred years (around the globe [Table 1] and across regions [Table 2]).
British: It was the warmest July in a hundred years (around the globe (Table 1) and across regions (Table 2)).
Avoid using nested parentheses in American writing: use square brackets within parentheses instead.
Punctuation around brackets
Punctuation is used the same way with brackets in both American and British styles: a punctuation mark (like a period,, or ) appears within parentheses or brackets if it belongs to the parenthetical text, and outside if it belongs to the larger sentence.
- Farley missed the train. (It left at 2 a.m. not 2 p.m.)
- Farley missed the train (which left at 2 a.m. not 2 p.m.).
- Let’s meet some day this week. (I’m free any day except tomorrow.)
- Let’s meet some day this week (except tomorrow).
- The apartment had a little sitting room (which the listing called a “drawing room”).
- She wrote back saying, “It’s small but has a small bedroom and a kitchenette (and even a little sitting room).” Let’s meet soon (today?).
- Can we meet soon (today)?
With brackets within brackets as well, the same rule applies. The only difference is that in American usage, square brackets appear within parentheses, while in British writing, round brackets are used within round brackets.
- American: Unfortunately, this study on pinnipeds is not as comprehensive as the authors claim. (Walruses, for example, were not included [why not?]).
British: Unfortunately, this study on pinnipeds is not as comprehensive as the authors claim. (Walruses, for example, were not included (why not?)).
- American: We studied various marine mammals (including pinnipeds [seals, sea lions, and walruses]).
British: We studied various marine mammals (including pinnipeds (seals, sea lions, and walruses)).
- American: Cacti are easy to grow. (See The Green Guide to Houseplants .)
British: Cacti are easy to grow. (See The Green Guide to Houseplants (1997).)