Final answer:
In English grammar, dashes are used to emphasize content in a sentence, set off appositives, and enclose nonessential information. They offer a stronger emphasis than parentheses and can indicate a pause or change of direction in the sentence.
Step-by-step explanation:
In the context of writing and grammar in the English language, when you add dashes between elements of a larger number, it is not only for the purpose of mathematical clarity, as when writing phone numbers or social security numbers, but can also be used in writing to set off or emphasize information. These dashes can also precede or enclose additional information that adds clarification, emphasis, or an appositive – a word or phrase that adds explanatory or clarifying information to the noun that it follows. An example would be using a dash to add an explanatory remark to a sentence without altering its basic meaning.
For instance, in 'The U.S.S. Constitution became known as "Old Ironsides" during the War of 1812—during which the cannonballs fired from the British H.M.S. Guerriere merely bounced off the sides of the Constitution,' the dash sets off an appositive that provides additional information about when the U.S.S. Constitution was nicknamed "Old Ironsides." The use of the dash here adds emphasis and clarification.
Dashes can also be used to set off nonessential information, highlight a contrast or pause, or mark a change of direction in a sentence's flow. The choice between using dashes and parentheses can affect the emphasis of the enclosed information, with dashes generally providing greater emphasis.