I got an email from a reader of several of my posts the other day.

I was wondering why do you use double dash in your posts? Is it followed by the rule or a personal style?

I responded as follows.

*****************************************************

Dear _______,

Thanks for the email. I can explain with an example or two.

“It was a fast-moving storm system.”

People think it’s a dash (between fast and moving). It’s actually a hyphen (-).

I think — but I’m not sure — that the L train should not be shut down this April.

The two hyphens (–) are what is actually, in printed matter, a dash — more specifically what a printer would call an em-dash. (The term em-dash comes from the days of typesetting. An em-dash was equivalent to the length of a capital M.) Two hyphens (–) in printed matter (such as a book) are set as a dash (—).

You can make an em-dash with word processing programs such as Word

or

you can just use the two hyphens, which, from the old days of typewriters, are understood to mean a dash.

So, a hyphen and a dash are not the same thing.

He told a side-splitting joke. (hyphen used)

I realized — I couldn’t quite believe it — that I had won the grand prize. (dash used)

Hyphens are used for compound words.

Dashes are used for an interpolated thought in a sentence.

— posted by Roger W. Smith

   January 2019