A dash is a horizontal line used to separate parts of a sentence — a dramatic substitute for a comma, semicolon, or colon. Your software may turn a typed dash, two hyphens without any spaces, to an unbroken line.
| 26a | Use a dash to indicate a sudden break in thought or shift in tone |
The dash signals that a surprise is in store: a shift in viewpoint, perhaps, or an unfinished statement.
Ivan doesn’t care which team wins — he bet on both.
I didn’t notice my parents’ accented speech — at least not at home.
| 26b | Use a dash to introduce an explanation, an illustration, or a series |
appositive: A word or group of words that adds information by identifying a subject or object in a different way: my dog Rover, Hal’s brother Fred
Use a dash to add an informal preparatory pause or to introduce an appositive that needs drama or contains commas.
My advice to you is simple — stop complaining.
Longfellow wrote about three young sisters — grave Alice, laughing Allegra, and Edith with golden hair — in “The Children’s Hour.”
| 26c | Use dashes to set off an emphatic aside or parenthetical expression from the rest of a sentence |
parenthetical expression: An aside to readers or a transitional expression such as for example or in contrast
It was as hot — and I mean hot — as the Fourth of July in Death Valley.
| 26d | Avoid overusing dashes |
To compare dashes with commas, see 21, and with parentheses, see 27a–27b.
The dash becomes meaningless if used too often. Use it only when a comma, a colon, or parentheses don’t seem strong enough.
| EXCESSIVE | Algy’s grandmother — a sweet old lady — asked him to pick up some things at the store — milk, eggs, and cheese. |
| EDITED | Algy’s grandmother, a sweet old lady, asked him to pick up some things at the store: milk, eggs, and cheese. |