Parentheses are most often used to identify material that acts as an aside (such as this brief comment) or to add incidental information.
Other punctuation marks used alongside parentheses need to take into account their context. If the parentheses enclose a full sentence beginning with a capital letter, then the end punctuation for the sentence falls inside the parentheses. For example:
Typically, suppliers specify air to cloth ratios of 6:1 or higher. (However, ratios of 4:1 should be used for applications involving silica or feldspathic minerals.)
If the parentheses indicate a citation at the end of a sentence, then the sentence’s end punctuation comes after the parentheses are closed:
In a study comparing three different building types, respirable dust concentrations were significantly lower in the open-structure building (Hugh et al., 2005).
Finally, if the parentheses appear in the midst of a sentence (as in this example), then any necessary punctuation (such as the comma that appeared just a few words ago) is delayed until the parentheses are closed.
You can also use parentheses to provide acronyms (or full names for acronyms). For example, “We use the MLA (Modern Language Association) style guide here” or “The Modern Language Association (MLA) style guide is my favorite to use.”
Remember, parentheses always appear in pairs. If you open a parenthesis, you need another to close it!
Have the parentheses been used correctly in the following sentences? Correct any errors you find.
- (Escobar et al., 2014) wrote about this phenomenon in their most recent paper.
- NASA (National Aeronautics and Space Administration) just announced three new initiatives.
- Michael lost the wrestling competition. (He also lost his temper).
- Helena took the chocolate bars (her favorites) and gave Davi the sour candies.
- No. Even parentheses are only used to cite information at the end of a sentence. A corrected version of the sentence would look something like these:
- Escobar et al. wrote about this phenomenon in their most recent paper (2014).
- A recent paper discussed this phenomenon (Escobar et al., 2014).
- Yes. Parentheses can be used to enclose the full name of an acronym.
- No. The second sentence is entirely in parentheses, so the period should be inside as well.
- Michael lost the wrestling competition. (He also lost his temper.)
- Yes. The phrase her favorites is a brief aside that can be enclosed by parentheses.