Section 15.8 Dashes and Parentheses
Both dashes and parentheses allow a writer to insert supplementary material into a sentence. Grammatically, they solve the same problem: how do you include information that is relevant but not central to the main clause? The difference is one of emphasis. Dashes are loud—they signal an interruption delivered with energy. Parentheses are quiet; they whisper supplementary information while the main clause continues.
Em Dash (—).
Sets off emphatic or interrupting material:
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The answer—surprisingly—was yes.
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She had one goal—and only one—to succeed.
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Three students—Maria, James, and Lin—volunteered.
Em dashes create stronger emphasis than commas. Use them when you want the parenthetical to stand out.
En Dash (–).
Indicates ranges and connections:
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pages 10–20
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the 2020–2021 academic year
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the New York–London flight
Parentheses ( ).
Enclose supplementary or explanatory material that the writer wants to de-emphasize:
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The results (see Table 3) were significant.
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She graduated in 2010 (the same year I started).
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The FANBOYS conjunctions (for, and, nor, but, or, yet, so) join independent clauses.
Parenthetical material can be removed without affecting the grammatical completeness of the sentence.
