The dash (—) is a punctuation mark and

The dash (—) is a punctuation mark and is intended to mark direct speech or highlight excerpts in texts. Although both punctuation marks (dash and quotation marks) serve the same purpose, it is more common to use dashes in dialogues, as they give the text more fluidity. On the other hand, they can be used to emphasize interspersed passages, thus replacing the commas, in which emphasis is intended.
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