Parentheses are used to enclose information that clarifies or acts as an aside to other information. Parentheses can be used inside or outside of a sentence.
John was having a terrible day. (He didn't know it was about to get even worse.)
When parentheses are used inside another sentence, commas (not in a series), semicolons, colons, and periods should go outside the last parenthesis. Exclamation points
and question marks should go inside the last parenthesis.
After two months of being late to class, Frederick (finally!) made it to his seat before the bell rang.
Parentheses that stand on their own always have their ending punctuation inside the last parenthesis.
The detective would not say anything more about the case at hand. (Do you think he even knows who did it?)
Remember that any information that is in parentheses is never a part of the subject. The verb should only agree with the noun/pronoun outside of the parentheses.
Brackets are almost exclusively used in quoted material, primarily as a way to clarify information. Do not use brackets and parentheses interchangeably.
"The year my book got published [1991] was also the year my first child was born," author Marsha Black said. "It was a wonderful time."
Any changes made to quoted material, such as capitalization, should be placed inside brackets.
Here is an example of it being quoted in a sentence with part of it changed:
Helen Keller wrote that "
[her] world is built on touch sensations, devoid of physical colour and sound; but without colour and sound it breathes and throbs with life."
Brackets can also be used to indicate spelling or grammatical errors in the material being quoted. Place [sic] after the mistake. This lets readers know that the mistake was in the original material, and not one the writer made.
Here is an example of how someone might quote the letter with its mistakes:
Writing to her brother, Duchess Verde lamented, "The seasons in Paris are lovely, but I have never been lonelyer
[sic]."
An ellipsis is a set of three periods with a single space on each side
( . . . ). In formal writing, ellipses are most often used to omit certain words in a quotation, or only use part of a larger quotation.
NOTE: When the words being omitted by an ellipsis are in the middle of a sentence, use the standard three periods.
If the words being omitted are between sentences, or there are other sentences after, include the period at the end of the sentence before placing the ellipsis.
Here is an example of how someone might use ellipses to shorten her quote.
Amelia Earhart said, "The most difficult thing is the decision to act, the rest is merely tenacity. . . . You can do anything you decide to do. . . ."
When using ellipses in a quotation, be sure not to change the meaning of the quotation in any way.
Here is an example of how not to use ellipses:
Amelia Earhart said, "The most difficult thing is . . . tenacity. The fears are . . . . change and control . . . and the procedure. . . ."
8th Grade Writing - Punctuation Lesson