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To explain and illustrate the uses of parentheses and brackets, mainly, but also braces, since they may be used in some cases.

This packet will show, in text (since I couldn't find any worthwhile [i.e., clear and concise] videos or other information), how parentheses and brackets are used. Please also read the three, related "Separation Punctuation" packets.

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 The Enclosing Punctuation Hierarchy:

1. Parentheses: enclose a sentence, clause, phrase, word, or number(s)

2. Brackets: enclose a sentence, clause, phrase, word, or number(s)

3. Braces: enclose a sentence, clause, phrase, word, or number(s)

Source: Adopted from The Oxford English Grammar, by Sidney Greenbaum, 1st Ed.


Parentheses (the round ones) v. Brackets [the square ones] and Braces {the squiggly ones}

The difference COULD be confusing in how they're used, but it isn't.

PARENTHESES enclose information that is not necessary for the sentence to make sense. Parenthetical information clarifies or further explains something, but the sentence would make perfect sense without the parenthetical information. 

EXAMPLE: The dam (what there was left of it) was made completely of twigs and mud.      "What there was left of it" obviously isn't necessary for the sentence to make sense.

Parentheses may be used in formal writing to add supplementary information, such as "Sen. John McCain (R., Arizona) spoke at length." 

They can also indicate "either singular or plural" for nouns – e.g., "the claim(s)." 

Any punctuation inside parentheses is independent of the rest of the text: "Mrs. Nickeldime (Yes, that was her name!) was my landlady."  Parentheses place more emphasis on the enclosed content than commas. Parenthetical text is usually short and again, unnecessary. It's added "for flavor," as it were.

IF the "teacher's pet" comment weren't there, we would put the "forgot her socks" comment in parens, and the "forgot one" comment in brackets. Remember the hierarchy: parentheses always come first.

Parentheses may also be used to enclose the numbers or letters in a list: 

(1) Blah, blah, blah.

(2) So on and so forth.

(3) Wordy, wordy, wordy.


The overuse of parentheses is bad writing. 

BRACKETS enclose information that is not written by the original author, such as explanatory notes or omissions, and especially in quoted text. 


No punctuation is required either before or after brackets, except as it would in the normal writing of the sentence. (See "the honor" in example 1, below, followed by a comma.)

No punctuation is required within the brackets, unless the bracketed material  is a complete sentence. 

OMISSION: "I appreciate [the honor], but I must refuse."

EXPLANATORY: "The future of psionics [see definition] is in doubt." 

1.  Below, the brackets enclosing the Latin (and therefore italicized) word "sic" are used to denote an error in spelling or the text information itself.

EXAMPLE: The Rosevelt [sic] family contributed two presidents.

2.  If you want to put a parenthetical expression within a parenthetical expression, you use brackets [ ]  for the second set. The punctuation hierarchy would look like this: ([]).

EXAMPLE: Linda (the teacher's pet [she forgot her socks!]) didn't want to speak in front of the class.  In this example, the comment, "the teacher's pet," isn't necessary, so it's enclosed in parentheses. The bracketed comment is inside the parentheses, so it's bracketed.

3,  Brackets may also be used to modify quotations.

EXAMPLE: if referring to someone's statement, "I hate to do laundry," one could write: She said that she "hate[s] to do laundry.

4.  A bracketed ellipsis [...] is often used to indicate omitted material.

5.  Bracketed comments may indicate when original text has been modified for clarity. 

EXAMPLE: "I'd like to thank [several unimportant people] and my parentals [sic] for their love, tolerance [...] and assistance [bold added]."

6.  In translated works, brackets are used to signify the same word or phrase in the original language to avoid ambiguity. 

EXAMPLE: "He is trained in 'the way of the open hand' [karate]." 

Source: The Oxford English Grammar, by Sidney Greenbaum, 1st Ed.; The Elements of Grammar, by Margaret Shertzer, 1st Ed.