Dash and the Interloper

What does that title even mean? I don’t know either, but you’re here so let’s talk about Shady Characters (or Shady Characters: The Secret Life of Punctuation, Symbols and Other Typographical Marks assuming you want the full title and subtitle, what a mouthful), a book about punctuation by Keith Houston.

I’ve seen hyphens before and I’ve noticed word processors insistence on turning short hyphens into longer hyphens (seemingly at random) when typing, but I never really knew why, or more correctly I’ve never explored why. At least not until someone informed me of the em-dash, used to bring together rapid changes in thoughts and phrasing or aposiopesis (the abrupt ending of a thought or phrase). I’ve always seen them as a sort of stand in for brackets (I use brackets frequently for side thoughts when I’m writing) but now I have a slightly better understanding of them. Anyone editing things I’ve written will probably let out a sigh of relief with that news. But I also wondered why I’ve never seen them and why their usage is mysteriously determined by the inner machinations of my word processor. Shady Characters has a whole chapter on the Dash and it’s friends, and the interloper, the ‘hyphen-minus’, and as per usual with typography and literature, we can blame the typewriter.
There’s a lot of consternation around the qwerty layout with the mechanical keyboards crowd, especially those seeking ever higher words-per-minute counts in their typing. Heatmaps abound showing that using qwerty has your fingers moving all across the keyboard just to type relatively simple words (if you haven’t noticed the most common letters, like vowels, are all over the place). There’s disputed reasons to this, that I won’t get into here, but it turns out the limited size of typewriters are what caused a lot of extra punctuation marks to disappear (or at the very least be relegated to somewhere in the Insert > Symbol menu of your word processor), such as the em-dash (—) and friends (‐,‑,‒,–), which all subsequently got turned into the hyphen-minus (-) which Houston indicates is the correct name for the hyphen we all use on a daily basis.

So let’s leave off with something useful, who cares about all those dead dash marks—apart from those who’ve carefully inserted them into the UTF-8, etc. character sets—let’s use the em-dash.
According to Merriam-Webster, the em-dash can mark and abrupt change or break in a sentence or its structure—sentence structure is for chumps anyway. Alternatively it can be used to indicate interrupted speech;

"Look, I'm not going to argue about starchy legumes—"
She cut him off, rolling her eyes, "I told you, potatoes are a—why is there a cat in my coffee?"

They are also often used to precede an author’s name at the end of a quoted passage.
Or like I do—or at least, thought I did—at the end of my posts.

—Mechaquill