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.
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?
- He finally arrived at a solution (after reading a dozen style manuals.)
- The Modern Language Association (MLA) has an online reference website.
- If the green light does not come on (See instruction booklet.) try the steps again.
- If the person responds that the computer is not running smoothly, the caller will ask the user to boot start up the system and report the start up time.
- No; the sentence is incorrect. The period is enclosed within the parentheses only if the entire sentence is within the parentheses.
- Yes. Initials for an organization or group can be enclosed in parentheses after the full name.
- Incorrect. Change “see” to lowercase and remove the period before the closing parenthesis.
- Incorrect. There should be parentheses around the phrase “start up”: ” . . . the caller will ask the user to boot (start up) the system. . .”