I can’t imagine why there’s a controversy around the use of the em dash, but there it is. My position? Use em and other types of dashes liberally, but accurately.
Like so much publishing terminology, the term “em” in “em dash” derives from the old days of printing and typesetting. The length of an em dash, far from being arbitrary, was equal to the width of the letter “m” in whatever typeface was being used. Simple.
The bigger question is when to use em dashes. That’s pretty simple, too, but also a bit sublime. I find that em dashes are all about pacing — (note the em dash) guiding the reader through your text. This is really useful in fiction. Storytelling with em dashes at just the right points is almost like being there — listening to you tell the story audibly.
Less-experienced writers sometimes use the ellipsis (the three-dot thingie) where they should being using an em dash. Ellipses indicate missing text: “His boring speech began with a joke…it ended with mild applause.”
There is also the “en” dash, which, you guessed it, is equal to the width of the letter “n” in the typeface. En dashes are used by rule to separate the elements of a range, as in pages 12–15, a connection, as is in the date 12–19–2025. It’s sort of like a hyper hyphen, which is just a shorter dash.
How do you insert em and en dashes? Your word processing tool may let you use the commands Insert and then Symbol. A faster way is to hold down Alt and type 0151 for an em dash or 0150 for an en dash. These numbers are part of the ASCII range of codes, but that’s another post.
For more on any of this, just consult your favorite search engine, AI tool, or Wikipedia. And have fun going crazy with dashes until you get them under control.

Effective copy editing removes verbal noise from your manuscript. Great copy editing is invisible and makes you look like a better author.