The En Dash
En dashes, which are about the width of an upper-case N, are often mistaken for hyphens. But, traditionally, en dashes function as a kind of super hyphen. They’re meant to give you a little extra glue when you have a compound modifier that includes a multi-word element that can’t easily be hyphenated. For example, the phrase Elvis Presley–style dance moves uses an en dash because Elvis-Presley-style dance moves is awkward; “Elvis Presley” isn’t a compound modifier, so hyphenating it looks odd. But, keep in mind, not all readers will notice en dashes or understand what they mean. Sometimes, it’s better to simply reword the phrase.
Elvis Presley–style dance moves
or: dance moves like Elvis Presley’s
pre–World War II buildings
or: buildings constructed before World War II
En dashes are also used to show ranges of numbers, such as times, page numbers, or scores (I’ll schedule you from 4:30–5:00). But, outside of formal printed publications, this type of en dash is commonly replaced with a simple hyphen.
The Em Dash
The em dash (about as wide as an uppercase M), is a relatively artistic punctuation mark, compared to the more technical hyphen and en dash. An em dash is most often used to indicate a pause in a sentence. It’s stronger than a comma, but weaker than a period or semicolon.
You can use a pair of em dashes to draw special attention to parenthetical information:
The new nurse—who was wearing the same purple scrubs as the old nurse—entered the room with a tray of Jello.
You can use a single em dash like a colon to add explanatory or amplifying information, especially when the information is surprising:
I opened the door and there she stood—my long lost sister.
Em dashes can also signal a sudden interruption, particularly in dialogue:
“Wait! I forgot to tell you—”
The door slammed shut between us and I missed whatever she was trying to say.
Whether or not you use spaces around your em dashes (word—word or word — word) is a matter of style. Whichever style you choose, use it consistently throughout your document.
Remember, em dashes are not interchangeable with hyphens. Using a single hyphen instead of an em dash can confuse readers and make your writing look unprofessional. If you’re writing text in a program or on a website where the em dash character is completely unavailable, use two hyphens together (–) to signify an em dash.