WRITING LESSON: DASH

A dash (publishers call it an "em-dash" because it's the width of the letter m) is used to mark a parenthesis — like this — or an interruption. Don't confuse it with a Hyphen, although you can use two hyphens -- like this -- for dashes in your papers. (Most word processors have a special symbol for the dash, which you can use if you like; note, though, that it's not always possible in every program, and they don't always come through in E-mail.) Whether dashes should have — spaces — around — them or not—like—this is a question of house style.)

There's nothing wrong with a few dashes here and there, but too many of them will make your writing less formal. Using them where other punctuation marks are proper is okay in informal correspondence, but out of place in most other kinds of writing.