Parentheses [( )]

These marks enclose words, phrases, and even whole sentences (but usually not more than a whole paragraph). If what is enclosed is a full sentence, the closing parenthesis follows the end punctuation; if not, the end punctuation is placed outside, as in the previous sentence here. More specifically, parentheses are used in four ways. First, they indicate interpolations and remarks by the writer of the text . Second, they specify, in one's own running text, an authority, definition, explanation, reference, or translation MEU1), it is correct to …>. Third, in reporting a speech, they sometimes indicate interruptions by the audience <“Finally—(laughter)—no, I'm really coming to an end now—(laughter)—let me say …”>. Fourth, parentheses separate reference letters or figures that do not need a full stop, e.g., (1)(a).

The first of those uses comes into play most frequently. The main test for whether a parenthetical construction works is whether the rest of the sentence makes sense without it. That's because words contained within parentheses do not affect the syntax of the rest of the sentence. E.g.: “We must determine whether each (or both) children are entitled to tickets.” The writer of that sentence could have avoided this error (each children are) by reading the sentence without the parenthetical phrase.

Virtually any punctuation mark is subject to an annoying overuse, but this is especially true of parentheses, which to be effective must be used sparingly. When they appear at all frequently, they tire the reader's eye, add to the burden of decoding, and deaden the reader's interest. Sentences can sag with all the qualifying parentheticals.