The em-dash is the most common dash seen in fiction writing. It’s called an em-dash because it’s about the same width as a printed capital letter M. When you use an em-dash, you should only use one at a time.
The em-dash is excellent at setting off parenthetical thoughts. Use one before and one after the additional information:
- Albert ran—well, more like stumbled—across the finish line.
- I couldn’t believe—or even comprehend—what I was seeing.
- Jenna slurped down the rest of her coffee—no cream, no sugar—then tossed the empty cup into the trash.
As you can see, the em-dashes in these sentences perform a similar function to parentheses. They add greater context to a detail mentioned in the sentence, though they aren’t integral parts of the sentence by themselves. Therefore, they’re set apart with em-dashes.
Em-dashes can be used alone to indicate a moment of surprise in writing:
- The baby cried and cried and—she stopped. Was someone playing “Baby Shark”?
- The match touched the wick, the fuse ignited—bang! The explosion boomed through the night.
- I smiled, breathed in the fresh air, and—coughed. Where had the smoke come from?
And they can also be used in dialogue to signify an interruption:
- “And then I went to school but school was closed because it was a snow day, so I sledded all the way back home and made myself a hot chocolate, but then the power went out, so I—”
“Okay, okay. You had a rough day. I get it!”
Like any tool, it’s best not to overuse em-dashes in our writing. If we do, our prose can become clunky and unsurprising. The old aphorism rings true here: less is more.
