Parentheses are used for asides or interruptions (to tuck additional information or explanation into or between sentences):
All of Wendell’s rubber chickens (which he had stolen from various joke shops) were lined up on the windowsill.
Snorg Ephelius Rondelblot the Fourth (known to his friends as Tommy) liked to hide in large mailboxes and scare passersby.
Archibald (as legend has it) was the inventor of the exploding watermelon.
If the aside occurs at the end of a sentence, put punctuation on the outside of the parentheses (unless both the aside and the material outside the parentheses are full sentences, in which case the period, question mark, or exclamation mark goes inside the closing parentheses):
Veronica often had nightmares about broccoli (though she occasionally dreamed about asparagus as well).
Veronica often had nightmares about Broccoli. (Betty seldom dreamed of vegetables.)
When an aside that occurs within a sentence contains a question or exclamation, the appropriate punctuation should be added inside the parentheses.
Timothy threw his bongo drums (the ones I gave him for Christmas!) at Dottie’s wedding cake.
See the main Grammar, Punctuation, and Writer Resources pages for more tips and resources.
References:
- American Psychological Association. (2011). “Punctuating Around Quotation Marks.” Blog.APAStyle.org.
- Brians, P. (n.d.). Common Errors in English Language.
- Capital Community College Foundation. (n.d.). “Quotation Marks” and “Commas.” Grammar.ccc.commnet.edu.
- Fogarty, M. (2010). Grammar Girl: Quick and Dirty Tips.
- O’Conner, P. T. (1996). Woe Is I, the Grammarphobe’s Guide to Better English in Plain English. New York, G. P. Putnam’s Sons.
- OWL at Purdue. (2013). “How to Use Quotation Marks” and “Extended Rules for Using Commas.” The Writing Lab & the OWL at Purdue and Purdue University. OWL.English.Purdue.edu.
- Strauss, J. (2013). Grammarbook.com.
- The Guardian. (2013). “‘The British style’? ‘The American way?’ They are not so different.” TheGuardian.com.
- Trask, L. (1997). Guide to Punctuation. University of Sussex.