Ever wondered how to use parentheses ( ) correctly in a sentence, or wondered what purpose they serve? Well, you’ve come to the right place. Check out the rules of parentheses below.

Parentheses ( ) are characters that are always used in pairs, and allow a writer to add additional (and non-essential) information into a sentence, whether it be a complete sentence, fragment, or single word.

The content inside the parentheses must not compromise the grammatical integrity of the sentence’s structure. To determine if your parentheses belong or if the sentence needs to be rewritten, simply read your sentence without the parentheses and their content. Is the sentence still grammatically correct? If so, great, keep the parentheses. If not, the sentence needs to be restructured.

Guideline 1: Use parentheses to enclose information that is to be used as an aside or afterthought.

She finally called back (after taking twenty minutes to mull things over) to say that she would not be attending the party that evening.

Guideline 2: Use parentheses to clarify preceding words.

Today we learned how to rate the severity of tornadoes on the FPP scale (also known as the Fujita-Pearson scale).

Guideline 3: Capitalize the first word in parentheses if it is a proper noun or the beginning of a complete sentence.

I met with the school Principal (Albert Ross) earlier this afternoon.

Confirm your purchases. (Check your receipt.)

Guideline 4: Use parentheses around an abbreviation or an acronym when it is used with the spelled–out word.

According to the WHO (World Health Organization), between 2030 and 2050, climate change is expected to cause approximately 250 000 additional deaths per year, from malnutrition, malaria, diarrhea, and heat stress.

Guideline 5: Use parentheses to reference or document sources, especially in academic writing, depending on the style being used.

Over 80% of employers use social media for hiring purposes. (See Infographic 1.)

Over 327 million people reside in America, making it the third most populous country in the world (Smyth 20).

Guideline 6: For purposes of clarity, you may choose to use parentheses around numerals used with a spelled–out number.

There are only one-hundred and eighty (180) days left until graduation.

Guideline 7: Use parentheses in a horizontal list of items that use either letters or numbers.

The following materials are required for participation in the course: (a) watercolors, (b) sketchbook, and (c) colored pencils.

Before leaving the office for the day, please: (1) refill the paper tray in the printer, (2) wipe down the kitchen counter, (3) enable the security system.

Guideline 8: Punctuation with parentheses varies. Please see below.

Commas are more likely to follow parentheses than precede them.

When she returned from the meeting (it was already after hours), she finished fixing her report.

When she returned from the meeting, (it was already after hours) she finished fixing her report.

If the information in parentheses calls for a question mark or an exclamation point, use the punctuation mark inside the parentheses only if the sentence ends with a different mark.

Terri Harper (remember her from school?) dropped by my office for coffee today.

You are very late (aren’t you?)!

When the words inside parentheses form a complete sentence, be sure to place a period inside the closing parenthesis.

Every employee is entitled to unlimited sick leave. (Refer to the company manual for details.)

When the words in parentheses do not form a complete sentence, place the period outside the closing parenthesis.

The company retreat has been rescheduled to next year (in late June).

Always place commas, semicolons, and colons outside the closing parenthesis.

Responsibilities of my new role include fieldwork (including house calls), management of case files, and community outreach.

See our next article about perfect tenses.