Many writers are more familiar with the actual punctuation marks than with their names. The question is, when should we use … (ellipsis) and when — (em-dash)?
According to The Chicago Manual of Style, the ellipsis indicates “faltering or fragmented speech accompanied by confusion or insecurity.” Here’s an example:
“I thought you said … but wait, yesterday I’m certain I heard you promise … didn’t I?”
On the other hand, the em-dash (longer than the en-dash and the hyphen) indicates a sudden break or an interruption.
“Don’t you walk out on me! I said, don’t—” The screen door banged shut, and his footsteps tatted down the stairs toward his car.
To remember the difference, I think of the three dots comprising the elipsis as slow: dot-pause, dot-pause, dot-pause. The em-dash, however, dashes in one straight, quick gesture.
Well, it works for me! 😉
![PowerElementsCharacterDevelopment[1000][1]](https://rebeccaluellamiller.files.wordpress.com/2015/05/powerelementscharacterdevelopment10001.jpg?w=205)
Rewrite, Reword, Rework 
I am writing about a writer who uses many em-dashes, and was wondering about the history of em-dashes. Was the em-dash first widely used in telegraphic — . — communications or earlier?
Craig, I’m unfamiliar with the history of the mark. You might try Wikipedia. They often have information on that kind of thing.
Thank you, that helps me a bunch!
I appreciate the feedback, Steve.
Becky