Parentheses () and Brackets []

Writers use parentheses to add extra information, examples, directions, comments, or other details. Although commas can often be used to replace them, parentheses help isolate information from the main part of the sentence, as follows:

Travel time from Dallas to Las Vegas is very rapid by air (only two hours).
You will find my new number (682-3750) to be very similar to my previous one (682-3570).

While commas are not needed before parentheses, be sure to use other punctuation correctly with parentheses. For example, if a complete sentence is within parentheses, then be sure to include the correct end punctuation within parentheses. However, if only part of the sentence is within parentheses, do not include end punctuation in the parentheses. Look at the examples below:

The neighborhood was very run-down and littered. (Some houses were even destroyed.)
Many of the players showed signs of influenza (fever, chills, headache, and nausea) after their coach fell ill.

Use brackets within quotations to enclose added, but necessary, information, as follows:

“This [newspaper article] proves nothing,” he said.
“He [Abe Lincoln] was also a scoundrel at times.”

Use brackets to identify errors in quoted material. The Latin word sic(meaning “thus”) is written in italics as well as enclosed in brackets immediately following a quoted error, as in this example:

The menu included “potatoe [sic] salad.”

Which sentence is correct? We had not planned on torrential rain (Five inches fell in three hours) during our hike. The airport was closed because of the heavy fog. (Only one plane had managed to land in the last twenty-four hours.)