Parentheses and Brackets
A B2 guide to enclosing marks — round parentheses for asides and clarifications, square brackets for editorial insertions inside quotations, and how to handle punctuation around them.
Two Pairs of Enclosures
Parentheses and brackets are paired marks that wrap around extra material. They look similar but do different jobs.
| Mark | Symbol | Main use |
|---|---|---|
| Parentheses (round brackets) | ( ) | aside, clarification, or extra information from the writer |
| Square brackets | [ ] | editorial insertion inside a quotation |
Note: in British English,
( )are often called “round brackets” and[ ]are called “square brackets”. In American English,( )are “parentheses” and[ ]are usually just “brackets”. This lesson uses the American terms.
Parentheses ( )
Parentheses enclose extra information that is not essential to the main sentence. The sentence should still make grammatical sense if you remove the parenthetical material.
Use 1: Asides and Clarifications
My car (a blue Toyota) is parked outside.
The conference (held last March) was a success.
She finally arrived (over an hour late) and apologized.
The aside can be a single word, a phrase, or even a full sentence.
Use 2: Definitions and Translations
The CEO (Chief Executive Officer) will speak first.
The book is in Spanish (the original language).
Konnichiwa (hello) is a common greeting.
Use 3: Citations and References
The study (Smith, 2020) confirms our hypothesis.
See chapter 4 (pages 80–105) for details.
Use 4: Numbering and Examples
Three steps: (1) plan, (2) draft, (3) revise.
Several countries (e.g., France, Spain, Italy) joined the agreement.
The abbreviation
e.g.means “for example”;i.e.means “that is” / “in other words”. Both are conventionally followed by a comma in American English.
Comparing Parentheses, Commas, and Em Dashes
These three marks can all set off extra material, but they signal different volumes.
| Mark | Volume | Example |
|---|---|---|
(parentheses) | quietest aside | My uncle (a chef) made dinner. |
, commas , | normal pause | My uncle, a chef, made dinner. |
— em dashes — | loudest, most emphatic | My uncle — a famous chef — made dinner. |
Punctuation Around Parentheses
Where to put commas, periods, and other marks depends on whether the material in parentheses is a fragment or a complete sentence.
Rule 1: Parenthetical Inside a Sentence
When the parentheses sit inside a larger sentence, the surrounding sentence’s punctuation goes outside the closing parenthesis.
We arrived early (around 6 a.m.), and the place was empty.
She missed the bus (her third miss this week).
| Right | Wrong |
|---|---|
She missed the bus (her third miss this week). | She missed the bus (her third miss this week.). |
Rule 2: Parenthetical as Its Own Sentence
When the parenthetical material is a complete sentence standing on its own, both the period and the parentheses are part of one unit, and the period goes inside.
The plan worked. (We were lucky.)
I finally finished the book. (It took me three months.)
Rule 3: Don’t Put a Comma Before Parentheses
Whatever punctuation would normally appear at that point in the sentence, place it after the closing parenthesis, not before the opening one.
| Right | Wrong |
|---|---|
When you arrive (at the south gate), call me. | When you arrive, (at the south gate) call me. |
Square Brackets [ ]
Square brackets are used for editorial insertions inside quoted material. They tell the reader: the writer added or changed these words; they are not in the original quotation.
Use 1: Adding Context to a Quote
The mayor said, "She [the governor] supported the bill from day one."
(The original quote was just “She supported…”; the writer added [the governor] to make it clear who “she” is.)
Use 2: Changing a Word for Grammar
The article noted that the company "[was] expanding into Asia."
(The original tense or form was changed to fit the new sentence. Brackets show the change.)
Use 3: [sic]
[sic] (Latin for “thus”) follows a quoted error to indicate that it appears in the original — not a typo by the writer.
The sign read: "Childrens [sic] menu available."
Use 4: Brackets Inside Parentheses
When something parenthetical appears inside another parenthetical, use square brackets for the inner one to avoid confusion.
(See the appendix [pages 200–220] for details.)
In British style, this nesting is sometimes reversed.
Common Mistakes
| Mistake | Fix | Why |
|---|---|---|
She arrived late, (an hour late) | She arrived late (an hour late). | Don’t put a comma immediately before an opening parenthesis. |
I went to Paris (last summer.) | I went to Paris (last summer). | When the parenthetical is part of a larger sentence, the period goes OUTSIDE. |
He said, "[She] is right." (when “She” was in the original) | He said, "She is right." | Only use square brackets for words you ADDED or CHANGED — not original ones. |
I love many cities (e.g. Paris, Rome). | I love many cities (e.g., Paris, Rome). | In US English, put a comma after e.g. and i.e.. |
My car, (a blue Toyota), is fast. | My car (a blue Toyota) is fast. | Use either parentheses or commas, not both. |
| Removing the parenthetical breaks the sentence | Rewrite the sentence | The sentence must still work if you delete the parenthetical. |
Practice: Exercises
Which sentence uses parentheses correctly?
Summary
Parentheses ( ) enclose the writer’s own asides, clarifications, definitions, citations, or list numbers. Whatever you put in parentheses must be removable — the surrounding sentence still has to work.
Square brackets [ ] are for editorial insertions inside quotations: clarifying who “she” is, fixing a tense to fit a new sentence, marking an original error with [sic], or nesting parenthetical material inside parentheses.
The big punctuation rule: when the parenthetical is part of a larger sentence, sentence-ending punctuation goes outside. When it stands alone as its own sentence, the period goes inside.
Don’t combine parentheses with commas around the same aside. And remember: parentheses signal the quietest kind of aside — em dashes are loudest, commas are in between.