Of the four types of brackets found in English punctuation marks, the square bracket is amongst the most popular. Alongside the parentheses, the square bracket works to separate words within text for added detail and information. 

The difference between parenthesis and bracket use is important, as each separates different types of information. With plenty of examples, read on to see how to use a square bracket properly. 

What Are Square Brackets Used For?

Square brackets […], also called brackets, are punctuation marks used to alter or add information to quoted material. They are always used in pairs and help offset information from the rest of a sentence in order to add information or detail. This is similar to how you use parentheses (also called round brackets). However, square and round brackets can’t be used interchangeably.

What is the Difference Between Square Brackets and Parentheses?

Square brackets are almost exclusively used within quotation marks to help make a quotation clearer or easier to understand. They offset words that help clarify, emphasize, or correct a direct quotation. 

A parenthesis is a type of bracket also known as a round bracket. They are used to offset words in texts to add additional information and detail. The words found between parentheses are unnecessary for understanding the passage, whereas brackets are often needed for a reader to understand the quote. 

The two other types of brackets are angle brackets (also known as chevrons) and curly brackets (also known as braces or curly braces). 

Rules of Square Bracket Use 

There are some very specific rules to bracket use. These rules and examples provide the information you need to use correctly in your writing and help make quoted material understandable and relevant. 

Rule #1

Use brackets to clarify nouns and pronouns in a quote that are unclear.

For Example

• He clearly stated that “there would be no merger with the [solar farm] company due to their poor weed management practices that used highly toxic weed control that ruined the soil.”

Rule #2

Use brackets to translate a foreign word or phrase in a quote. 

For Example

• Despite taking four years of German in High School, she “struggled with basic greetings when in the country, often replying ich weiss nicht [I don’t know] when spoken to in the native dialect.”

Rule #3

Use brackets to indicate the change of the first letter of quoted material from uppercase to lowercase or vice versa. 

For Example

• In 1913 her grandfather “[a]rrived alone at the age of 12 in Ellis Island to reunite with his family who had traveled to the coal mines of New Mexico.”

Rule #4

Use brackets surrounding the Latin term sic, meaning “thus” or “so,” to indicate an error or unusual word usage in a quote. This indicates the original writer included the error. 

For Example

• Our local horse racing track held “amateur jackpots each Thursday, Friday, and evry [sic] other Saturday morning.” 

You can also use a correction of the original material, complete with a question mark if you are guessing at the correction.

For Example

• “The history professor has traveled the world, including remote places like the Kerglen Islands [Kerguelen Islands?].

Rule #5

Use brackets to indicate when you change a quote to emphasize a specific portion of the passage.

For Example

• The professor shared his concerns over how many students “were apathetic to the learning process and were willing to throw away their tuition money when they skipped class [emphasis added].”

Rule #6

Use brackets to censor any inappropriate materials found in the original text. 

For Example

• She lost her cool with the group, telling them to “sit the [expletive] down.”

Rule #7

Use brackets inside parentheses to replace parentheses inside parentheses. 

For Example

• We traveled exclusively by car when the children were young (so we could stop [exposing them to more history] whenever we wanted). 

Square Bracket Examples in Writing

Brackets are an acceptable punctuation mark to use in both formal and informal use when quoting materials. 

And another: “Perhaps somebody will take the hint and explain [the purpose of square brackets].” (The Guardian)

While on the topic of doubt, why oh why did anyone doubt MWD’s assessment that Morry Schwartz’s The [Boring] Saturday Paper is, well, boring? (The Australian)

Let’s Review

Square brackets, also called brackets, are one of four different types of brackets used to offset words in various texts. Square brackets are commonly used for quoted material to help define and bring clarification of direct quotations to readers. Be sure to refer to the rules associated with their use to help make your writing understandable and more concise.