Emily Dickinson may have taken the use of dashes to the extreme, but TBH they are often my favorite type of punctuation.
How can you tell the difference? Think of the typeset width of the letter "n" versus the letter "m."
Hyphen: -
En dash: –
Em dash: —
Some like to use the en dash and hyphen interchangeably, though they serve different functions.
A hyphen connects words or parts of words, while an en dash's raison d'être is to replace the prepositions "to" or "through" in a number range or time span. (i.e. I'll eat 3–26 cookies from 7–9 pm.)
Ah, the em dash though!
These gems can replace awkward or unclear parentheses, commas, and even colons, but the true joy lies in the priority em dashes impart. It's a signal that the following phrase is REALLY IMPORTANT STUFF, so pay attention.
You can space an em dash as you like.
Thank the AP style guide for this wiggle room. Spaces are required on either side of an em dash, not only to avoid awkward line spacing but also to help with readability.
i.e. "The best thing since sliced bread — until now."
Image: sliced bread