What are parentheses?
Parentheses ( ( ) ) are used to separate information that is not necessary to the structure or meaning of the surrounding text. Similar to quotation marks, parentheses are always used in pairs—we cannot have a single parenthesis (the name for one of the brackets on its own) without its match appearing elsewhere nearby. (The one exception is when we write vertical lists, which we’ll look at later on.)
Parentheses indicate parenthetical information—that is, any additional information that is not integral to the writing that appears outside of the parentheses. This information may comprise a fragment (a word, phrase, or clause) or one or more complete sentences. How we use parentheses in relation to other punctuation depends on the length of the information they contain.
When parentheses enclose a word, phrase, or dependent clause, they will generally appear within a sentence, since the information usually can’t function as a sentence alone.* When this is the case, the parentheses must appear adjacent to any other existing punctuation within the sentence. For example:
- “As I have said before (on numerous occasions), we must find a long-term solution to this problem.”
- “I want to tell you something that you must always remember (even after you’ve moved away): We will always be here to support you, no matter what.”
- “Who will be coming to the party on Saturday (other than us, obviously)?”
- “This calls for congratulations (and celebration)!”
Although parenthetical fragments cannot use periods when appearing within a sentence, they are able to take exclamation points or question marks, depending on their meaning and intention. For example:
- “Arnold Schwarzenegger (spelling?) was a huge action icon in the ’80s and ’90s.”
- “The goal by Hendrickson (and what a goal!) secured the team’s entry into the championship.”
- “With the commission we’re expecting to receive from the deal (details finalized yet?), our shares should rise to their highest level in years.”
We can also place exclamation points and question marks on their own inside of parentheses to indicate surprise, excitement, or doubt about something that just preceded them. For instance:
- “The value of the British pound dropped nearly 10 per cent (!) following the UK’s decision to leave the European Union in 2016.”
- “She said I had behaved ‘like a yak’ (?) as she was leaving.”
(*Note that, on occasion, a parenthetical word or phrase may be used as a complete sentence, in which case parentheses can be used outside of another sentence. We’ll look at some examples of these a little later.)
Using parenthetical fragments correctly
Because parenthetical elements are grammatically independent of the sentence they appear in, we must be sure that they do not include information that is necessary to complete the meaning of the overall sentence. We can easily check this by reading the sentence without the parenthetical element: If the sentence doesn’t make sense without it, then we will need to rewrite the sentence or remove the parentheses. Let’s look at a few examples that demonstrate this.
- “I knew John would agree with me (he always does!), so I didn’t bother consulting him on the matter.”
- “I knew John would agree with me, so I didn’t bother consulting him on the matter.”
As we can see, the sentence still makes complete sense grammatically, so the parentheses have been used correctly.
- “I’ve packed some sandwiches, bananas, carrots (and a few chocolate bars) for the train ride.”
- “I’ve packed some sandwiches, bananas, carrots for the train ride.”
The sentence is no longer grammatically correct if we remove the parenthetical element, so either the parentheses must be removed or the sentence must be reworked:
- “I’ve packed some sandwiches, bananas, carrots, and a few chocolate bars for the train ride.”
- “I’ve packed some sandwiches, bananas, and carrots (and a few chocolate bars) for the train ride.”
When a parenthetical element stands on its own as a complete sentence (or multiple sentences), then the opening parenthesis will appear after the period of the previous sentence, and the closing parenthesis will appear before the first word of the next sentence (unless it appears at the end of a paragraph). The sentence within will end with a period, question mark, or exclamation point of its own, which will appear inside the closing parenthesis. For example:
- “The last time I went to Toronto, I had an awful experience. (I won’t be visiting again any time soon!)”
- “You can also choose to send in your application by mail. (I wouldn’t recommended it, though, as it will only add more time to the process.) If you would like to do so, use the mailing address listed at the bottom of the form.”
- “I was left completely speechless when I met Michael Jordan. (How else could I be after meeting my lifelong hero?)”
It’s also not uncommon for words and sentence fragments to be used as complete sentences (known as minor sentences or irregular sentences) within parentheses outside of the regular sentence. This is often done to put extra emphasis on the parenthetical information, while still making it clear that it is operating as an aside, commentary, or non-integral element. For example:
- “I had a few choice words for him after the meeting. (Just a few!)”
- “The president has described the results as ‘shocking.’ (Shocking? Really?)”
- “He has been accused during the election of only being concerned with the stability of big corporations. (Which is nonsense.)”
Complete sentences within sentences
Note that we can also have a complete parenthetical sentence that appears within another sentence. In this case, we treat it the same way as a parenthetical fragment: we do not capitalize the first letter of the sentence if it isn’t a proper noun or pronoun, and we do not end it in a period (though we still use a question mark or exclamation point, if appropriate). For instance:
- “I won’t bore you with the details (it’s not a very interesting story), but suffice to say that I’m looking for a new job.”
- “We’re going to be very busy this weekend (I don’t need to tell you that!), so everyone needs to be in top form.”
- “On Tuesday I’ll be visiting your great-uncle Michael (do you remember him?), so I won’t be home to fix you dinner.”
Substituting em dashes
Parentheses can often be replaced by em dashes in a sentence if we want (or ought) to draw more attention to the information within them. Just be aware that em dashes are considered much less formal than parentheses, so they should be avoided when writing professional or academic material.
While we always use two parentheses, we only use one dash if the parenthetical information comes at the beginning or end of a sentence. Additionally, a set of parentheses will operate in conjunction with surrounding commas, while em dashes will replace them altogether.
Let’s look at some examples:
- “I know that my friend Stephen (the poor dear!) has found living on his own very difficult.”
- “I know that my friend Stephen—the poor dear!—has found living on his own very difficult.”
- “As part of the centenary commemorations for the sinking of the RMS Lusitania (May 7, 1915), Irish President Michael Higgins participated in a wreath-laying ceremony in County Cork.”
- “As part of the centenary commemorations for the sinking of the RMS Lusitania—May 7, 1915—Irish President Michael Higgins participated in a wreath-laying ceremony in County Cork.”
- “Knowing how difficult it is to look after just one child, I’ll never grasp how my mother managed, considering how many children (nine in all) she raised more or less on her own.”
- “Knowing how difficult it is to look after just one child, I’ll never grasp how my mother managed, considering how many children—nine in all—she raised more or less on her own.”
Note that em dashes should not be substituted for parentheses in more technical, specialized uses (which we’ll look at later).
Parentheses within parentheses
Very occasionally, we might have a larger parenthetical element that contains one or more smaller ones. Conventionally, the smaller parenthetical element will be enclosed within brackets ( [ ] ) to distinguish it from the parentheses of the larger text. While it is not uncommon to see multiple sets of parentheses used within one another (sometimes known as nested parentheses), this is generally discouraged, especially in more formal, academic, or professional writing.
- “The authors maintain that the correlation is strong enough to assume causation (though they make this claim ‘with caution’ [Wilson, Dobs, et al., 2010]).”
- “The authors maintain that the correlation is strong enough to assume causation (though they make this claim ‘with caution’ (Wilson, Dobs, et al., 2010)).”
- “At least I’ll have some extra spending money this summer. (My cousin got me a job at my uncle’s [his dad’s] warehouse.)”
- “At least I’ll have some extra spending money this summer. (My cousin got me a job at my uncle’s (his dad’s) warehouse.)
In more informal writing, we could also substitute the internal parentheses with one or two em dashes:
- “At least I’ll have some extra spending money this summer. (My cousin got me a job at my uncle’s—his dad’s—warehouse.)”
Note that it is quite common to see nested parentheses in conversational writing; most of the time, readers will have little trouble keeping track of them. If you are writing for work or school, be sure to use brackets, as it is the most correct; otherwise, use whichever method looks best.
We should always avoid putting two parenthetical elements back-to-back. For example, the following sentence would be incorrect:
- “I don’t know, Jack. I’ve never been there before (and neither have you)(I think!).”
Depending on the sentence, we can either place one inside the other, merge the information into a single parenthetical element, or simply rework the sentence altogether:
- “I don’t know, Jack. I’ve never been there before (and neither have you [I think!]).”
- “I don’t know, Jack. I’ve never been there before (and neither have you, I think!).”
- “I don’t know, Jack. I’ve never been there before, and neither have you (I think!).”
In addition to indicating parenthetical information that supplements the rest of the writing, there are also a number of technical uses for parentheses.
Explaining or introducing acronyms and initialisms
Acronyms and initialisms are forms of abbreviations in which the first letters of multiple words are used to represent the phrase or name as a whole. (Acronyms are such groups of letters that are pronounced as a word, while initialisms are read as their individual letters—though most people simply refer to both as acronyms.)
We often see parentheses used to explain what acronyms and initialisms stand for. Conversely, we can also put the acronym or initialism itself into parentheses after the full phrase or name if the abbreviated form will be used throughout the rest of the document. Here are some examples:
- “The OMB (Office of Management and Budget) has just released new figures.”
- “Text messaging has given rise to all sorts of abbreviated writing, such as LOL (‘laugh out loud’), BRB (‘be right back’), and BFF (‘best friends forever’).”
- “The Organization of the Petroleum Exporting Countries (OPEC) has expressed concern as shares in global oil corporations continue to fall.”
- “Forces have already been deployed by the North Atlantic Treaty Organization (NATO) into the region, though the Secretary General of NATO has made assurances that it is a precautionary measure at this stage.”
Translating foreign text
If we include writing that is in a foreign language and wish to include a translation (or the original characters, if the language uses non-Arabic lettering), we can place it in parentheses immediately after the foreign text (which will usually be in italics). For example:
- “The only thing I ever learned to say in Spanish is una mas, por favor (one more, please).”
- “Many tourists visiting Japan incorrectly use konnichiwa (こんにちは or in kanji 今日は, meaning ‘good afternoon’) as a greeting at any time of day.”
Numbered and lettered lists
When we write lists that require a certain structure or order, we can include numbers or letters before the items within it. If the list is written into the flow of the overall sentence, we surround the number or letter with parentheses, and we end each item with a semicolon. For instance:
- “Your assignment for the evening is as follows: (1) interview an older relative about his or her experiences growing up; (2) write down your own experiences for the same time period; (3) write a one-page report that compares and contrasts your experiences to those of your relative.”
- “We’ll need four things for the upcoming audit: (a) copies of all bank statements over the last year; (b) a letter from the bank confirming the company’s signatories; (c) any receipts for business-related purchases made this year; (d) a profit and loss report for the year to date.”
However, if such lists are structured vertically, then we typically only use an end parenthesis after the number or letter. (This is the only instance in which it is acceptable to use a single parenthesis mark on its own.) Here are the same two lists structured vertically:
“Your assignment for the evening is as follows:
- 1) Interview an older relative about his or her experiences growing up.
- 2) Write down your own experiences for the same time period.
- 3) Write a one-page report that compares and contrasts your experiences to those of your relative.”
“We’ll need four things for the upcoming audit:
- a) Copies of all bank statements over the last year
- b) A letter from the bank confirming the company’s signatories
- c) Any receipts for business-related purchases made this year
- d) A profit and loss report for the year to date”
Years of birth and death
When writing biographical information about a particular person (especially in academic writing), we often list the years of his or her birth and death in parentheses after his or her name. This is expressed as a range, so we often use an en dash to join the two numbers, as in:
- “John F. Kennedy (1917–1963) was the 35th president of the United States.”
Note that we can also use this form for similar date ranges as well, such as when listing the period of time in which a person has served in a particular position. For instance:
- “During her time as CEO (2007–2011), she helped to spearhead the new product line.”
Time zones and telephone numbers
We can also use parentheses to specify the time zone when we indicate a particular hour:
- “So we’re agreed: the next board meeting will take place on June 23 at 8 AM (PST).”
If we are clarifying what the hour will be in a different time zone with parentheses, then we do not need a separate set of parentheses:
- “Voting will begin across the UK at 7 AM (2 AM EST) on Thursday.”
Another technical use of parentheses in North America is to separate an area code from the rest of a telephone number, but styles vary by country.
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