Parentheses vs. Brackets: A Comparative Guide

Both parentheses, ( ) and brackets [ ] are punctuation marks. In English writing, they are generally used to separate certain words from the rest of the sentence. 

What differentiates the two, is how they are used to separate a phrase or information. Parentheses set off additional information or digressions from the main idea of the sentence, while brackets are primarily used within quotes or quotations. 

Learn more about parentheses vs. brackets in this comparative guide. Then, review your content for proper grammar, spelling, and punctuation with the Originality.ai Grammar Checker.

What Are Parentheses?

Parentheses are also referred to as round brackets (highlighting their round shape). 

A single parenthesis is spelled with an ‘i’ and multiple parentheses are spelled with an ‘e’.

Parentheses are used in pairs, like quotation marks, to surround the words separated from the remainder of the sentence: 

• An opening parenthesis: (
• A closing parenthesis: ) 

When do you use parentheses?

These punctuation marks are used to enclose additional information to describe or clarify a point. They may also add a digression or afterthought from the writer.

However, it is still important for the sentence to be grammatically correct and complete without the text inside the parentheses. To test the grammar of the sentence, try reading it without the words in the parentheses. 

Other uses for parentheses include citations and reference lists such as for common style guides: APA, MLA, and Chicago style. This is particularly common in academic writing and papers.

Examples of parentheses in sentences

Use 1: Add extra information to a sentence:

• The Grand Canyon (one of the Seven Natural Wonders of the World) attracts millions of visitors each year.
• My friend, Maria (who lives in Spain), sent me a beautiful postcard.

Use 2: Add a digression or author’s note:

• The conference starts at 9:00 o’clock (don’t forget to arrive 15 minutes early for registration). 
• The recipe called for saffron (who even has that in their pantry?) to give the dish its distinct flavor.

Use 3: Define acronyms

• All employees must complete the Occupational Safety and Health Administration (OSHA) training by the end of the month.
• The spacecraft was launched by NASA (the National Aeronautics and Space Administration) on schedule.

Use 4: Cite sources 

• “To be, or not to be: that is the question” (Shakespeare, Hamlet)

How to use punctuation with parentheses

Parentheses have different rules when used with other punctuation marks. If the parentheses set off an aside within the sentence, extra punctuation may not be required. 

If the parentheses are at the end of a complete sentence, then for proper punctuation put the period after the sentence “).”. The only instance where you place a period within the parentheses is if the sentence inside the parentheses is a complete sentence itself.

Let’s take a closer look at period and parentheses punctuation examples:

Period placed outside the parentheses:

• The book is 300 pages long (excluding the appendix and bibliography).

Period placed inside the parentheses:

• We decided to take a detour to the lake. (It turned out to be the highlight of the trip.)

Exclamation marks are used similarly to a period in conjunction with parentheses. 

If the exclamatory sentence includes parentheses, the exclamation mark will go outside the parentheses at the end of the sentence. 

If the entire exclamatory remark is inside the parentheses, then the exclamation mark will be inside the parenthesis as well.

Examples of parentheses and exclamation marks for punctuation:

Exclamation marks placed outside the parentheses:

• What an incredible performance that was (especially considering it was their first show)!

Exclamation marks placed inside the parentheses:

• We finally reached the summit after hours of climbing. (What an incredible view!)
• The cake was gone within minutes (such a hit!) at the party.

Then commas follow the parentheses within a sentence. They don’t appear before the opening parenthesis.

Examples of commas and parentheses punctuation:

• The event was a huge success (thanks to everyone's hard work), and we’re planning another one soon.
• We had a great time at the beach (perfect weather for it), and we stayed until sunset.

What Are Brackets?

Brackets, also called square brackets, are primarily used as editorial marks within quotations. This means they generally appear within someone else’s words or information. 

When writers strive to seamlessly incorporate quotations into their own work, it is often necessary to make small edits or adjustments to the original source material.

Brackets can be used to show where words have been added to the original quotation, where words have been omitted from the quotation, to indicate when edits have been made, and to note any errors made in the original quotation. 

In other words, brackets are used to put parentheses inside of parentheses.

Examples of brackets in sentences

Use 1: Adding words to a quotation

• “The [cold] weather has arrived quickly in the region.”
• “Timothy gave [his boss] the marketing report on Monday.”

Use 2: Omitting sections of a quotation

• Original: She said, “The weather was brilliant last weekend and so we went skiing.”
• Edited:  She said, “The weather was brilliant [...] so we went skiing.”
  An ellipsis is indicated with three dots inside a pair of brackets.

Use 3: Making edits or correcting grammatical errors in a quotation

• Edited: The note read: “Call the contrators [sic] before work”.

The term “sic” means “it is so.” It is often used to note that a grammatical error was part of an original quotation.

Use 4: Brackets inside parentheses

• She decided to take a gap year to travel the world (her friends [especially her best friend] helped her plan out the travel itinerary).

Final Thoughts: When to Use Parentheses vs. Brackets

When using parentheses versus brackets in writing, there is one basic rule to remember for each. Use parentheses when adding additional information to your own writing. Use brackets when adding additional information to or adjusting someone else’s writing to fit your own work.

Review your content for proper punctuation (like parentheses vs. brackets), spelling, and grammar with the Originality.ai Grammar Checker.

Then, read our top resources for more grammar insights:

• What Are Hyphens Used For?
• When to Use a Colon in Writing for Punctuation
• Independent Clauses: A Complete Guide
• Dependent Clauses: A Complete Guide