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Using Brackets
The Rules for Using Round and Square Brackets
Round brackets are used to add information to text or to show a plural option, e.g., "add the apple(s)." Square brackets are used to clarify quoted words, usually by showing changes to the original quotation.Table of Contents
- Three Ways to Use Round Brackets
- Two Ways to Use Square Brackets
- Round Brackets Explained in Detail
- (1) Using Round Brackets to Insert Additional Information into Text
- (2) Using Round Brackets to Introduce an Abbreviation
- (3) Using Round Brackets to Show a Plural Option
- Why Round Brackets Are Important
- Square Brackets Explained in Detail
- (1) Using Square Brackets to Show That Text in a Quotation Was Not in the Original.
- (2) Using Square Brackets to Show That Text in a Quotation Was in the Original
- Why Square Brackets Are Important
- Video Lesson on Square Brackets
- Printable Test

Three Ways to Use Round Brackets

Round brackets are used in three ways:
(1) To insert additional information into text.
- The stegosaurus (the best-known herbivorous dinosaur) had a brain the size of a ping pong ball.
(2) To introduce an abbreviation.
- Neil Armstrong was selected to join the National Aeronautics and Space Administration (NASA) in 1962.
(3) To show a plural option alongside a singular one.
- Do not remove the pin(s) while the light is on.
Two Ways to Use Square Brackets

Square brackets are used in two ways:
(1) To show that text in a quotation did not feature in the original.
- (1a) Square brackets can be used to explain something in a quotation.
- Original quotation: "It is a contradiction in terms."
- Amended: "It [military intelligence] is a contradiction in terms."
- (1b) Square brackets can be used to modify a quotation.
- Original quotation: "It is a contradiction in terms."
- Amended: "[Military intelligence] is a contradiction in terms."
- (1c) Square brackets can be used to replace unnecessary text with [...] (called an ellipsis).
- Original quotation: "I don't want any yes-men around me. I want everybody to tell me the truth even if it costs them their jobs."
- Reduced: "I don't want any yes-men around me [...] even if it costs them their jobs."
(2) To show that text in a quotation did feature in the original.
- In your statement, you wrote: "I appraised [sic] him of the situation at about 4 o'clock."
Round Brackets Explained in Detail
(1) Using Round Brackets to Insert Additional Information into Text

- The stegosaurus (a genus of herbivorous thyreophoran dinosaur) was predated by the allosaurus.
- The stegosaurus (the herbivore with tiles on its back and a spiky tail) weighed the same as a car.
- The plates on a stegosaurus's back were for display. (It is unlikely they had a thermoregulatory function like an elephant's ears.)
(2) Using Round Brackets to Introduce an Abbreviation

- The Master of Business Administration (MBA) teaches approaches to business management.
(3) Using Round Brackets to Show a Plural Option

- Remove the sheet(s) so the air can flow freely
- Please append the name of your guest(s) to the list.
- Ensure the rod(s) is(are) aligned with the top section.
- The routine uses the output(s) of that(those) process(es).
- The routine uses output of that process(es).
- Bring your A game on Monday. We're going to crack Mission (Im)possible.
- I'm calling it an (experi)mental project.
(Issue 1) Brackets are considered informal.
Brackets are a great way to add additional information because they're easy to spot. This means they won't disrupt reading flow. There's a problem though. Brackets are considered informal, and lots of businesses and universities do not permit their use in formal documents. Don't worry. There's a solution. Using brackets is just one of your options for inserting additional information. You can also use commas or dashes.- The stegosaurus, the best-known herbivorous dinosaur, had a brain the size of a ping pong ball.
- The stegosaurus – the iconic dinosaur that lived 150 million years ago – had a top speed of 5 mph.
- A large stegosaurus could be 9 metres (29.5 feet) long and weigh 7 tons (15,432 pounds).
(Issue 2) Uncertainty over whether a period goes inside or outside the close bracket.
The big question with brackets is where to put the end punctuation, which is usually a period (full stop). Does it go inside or outside the brackets?When using brackets, the positioning of end punctuation follows logic. Sometimes it goes outside the close bracket, and sometimes it goes inside. For example:
- She will ride a pony. (However, she will not ride a Dartmoor pony.)
- She will ride a pony (but not a Dartmoor pony).
- She will ride a pony (she told me yesterday) but not a Dartmoor pony.
- The group paid with a stolen credit card (my credit card!).
- The group paid with a stolen credit card (didn't you lose your card?).
(Issue 3) Uncertainty with capital letters when expanding an abbreviation.
When introducing an abbreviation, there's nothing to think about if the abbreviation represents the name of something (i.e., a proper noun). In other words, the expanded version is written with capital letters.- The motto for the Federal Bureaux of Investigation (FBI) is "fidelity, bravery, integrity".
- Food crops are the most controversial genetically modified organism (GMO). (The full version of the abbreviation isn't immediately obvious.)
- The term Genetically Modified Organism (GMO) was popularized by the media not scientists. (The capital letters aren't justifiable under capitalization rules, but the definition of the abbreviation now stands out.)
- Brackets are a great way to insert additional information (called a parenthesis).
- You can insert additional information using commas or dashes if you think brackets are too informal.
- The placement of end punctuation with a close bracket follows logic (like this). (It just follows logic.)
Square Brackets Explained in Detail
(1) Using Square Brackets to Show That Text in a Quotation Was Not in the Original

In these examples, the original text is intact, but an explanation is inserted using square brackets.
- "Most people save all their lives and leave it [their money] to somebody else." (Actress Hedy Lamarr)
- "It [electricity] is really just organized lightning." (Comedian George Carlin)
Using Square Brackets to Modify a Quotation
In the next examples, the original text has been modified. The words that needed explaining have been replaced with the explanations.- "Most people save all their lives and leave [their money] to somebody else."
- "[Electricity] is really just organized lightning."
- Angela Merkel believes "it's [her] damn duty and obligation to do everything possible for Europe to find a united path."
- Quoting author Flannery O'Connor, Jason often reminded his children that "[t]he truth [did] not change according to [their] ability to stomach it."
- Alice Cooper famously said that "from the moment [he] leave[s] [his] house or hotel room, the public owns [him]."
- Alice Cooper famously said: "From the moment I leave my house or hotel room, the public owns me."
Using Square Brackets to Replace Unnecessary Text
Three dots (called ellipsis) are often used to show that text has been omitted from a quotation. An ellipsis punctuation mark is written "..." or "[...]".- Education is the most powerful weapon [...] to change the world. (President Nelson Mandela)
- Andy Warhol is the only genius [...] with an IQ of 60. (US author Gore Vidal)
(2) Using Square Brackets to Show That Text in a Quotation Was in the Original

Using Square Brackets with [sic]
The term "[sic]" shows that the preceding text featured in the original quotation. Often, "[sic]" is used to indicate that a writing error was committed by the original author.- He claimed his statement was "appropriate and did not undermine the moral [sic] of our troops." (It should be morale not moral.)
(Reason 1) Square brackets allow you fit quotations snugly into your work.
Quotations are a great way to incorporate information from other sources into your writing, and they are particularly useful for supporting arguments. Quotations carry a sense honesty and believability. They're like an impartial vote for your assertion. You can use square brackets to trim quotations fit snugly into your writing. So, chop and change away, but remember not to change the intended meaning.(Reason 2) Slam someone with [sic].
If you're ever the recipient of antagonistic correspondence that contains a writing error, you could use [sic] to slam the sender for their error.- Antagonist: I am not adverse to change, but I will not be voting for your proposal.
- You: I'm pleased you're not adverse [sic] to change because my proposal has been approved. (The antagonist should have used "averse." Using [sic] this way fairly aggressive. Use sparingly.)
Are you a visual learner? Do you prefer video to text? Here is a list of all our grammar videos.
- Use square brackets to make quotations clearer or a better fit for your work, but take care not to change the original meaning.
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