You can set off extra information with commas. Two other marks do the same job in a different tone of voice. The dash (—) is loud: it makes a sharp break or stresses what it sets off. Parentheses ( ) are quiet: they tuck in an aside. An ellipsis (…) shows that words were left out.
| Mark | Same sentence | Effect |
|---|---|---|
| commas | Our dog, a very old beagle, still chases squirrels. | ordinary extra |
| dashes | Our dog—a very old beagle—still chases squirrels. | stressed, louder |
| parentheses | Our dog (a very old beagle) still chases squirrels. | a quiet aside |
Key idea
Dashes set off a sharp break or something to stress; parentheses set off a quieter extra; an ellipsis marks words left out of a quotation, or a trailing pause. A dash is not a hyphen: the hyphen (-) is short and joins words.
Why it works
These marks let a writer control emphasis. If everything is set off with dashes, nothing stands out, so save the dash for the one thing you want the reader to notice.
Worked example: A dash at the end
“There was only one thing left to do, run.”
- The last word is a sharp turn, and the writer wants it to land.
- A dash gives it that weight.
Answer: There was only one thing left to do—run.
Worked example: Shortening a quotation
Strunk wrote: “In a series of three or more terms with a single conjunction, use a comma after each term except the last.” Leave out “with a single conjunction.”
- Take out the words, keeping the meaning the same.
- Put an ellipsis where the words were.
Answer: “In a series of three or more terms … use a comma after each term except the last.”
Worked example: Parentheses and the period
“We hiked for six hours (with two short breaks).”
- The words in parentheses are part of the sentence.
- So the period goes outside the closing parenthesis.
Answer: We hiked for six hours (with two short breaks).
Common mistake
Typing a hyphen for a dash (“I was tired - very tired”). Most word processors turn two hyphens into a dash, or you can insert the em dash (—) from the symbols menu. Also: a dash in the middle of a sentence needs a partner, just like a pair of commas, and an ellipsis must never change what the original said.