My Pet Punctuation Peeve

by Allen Downey

Stop using hyphens as dashes.

A hyphen is a short line that goes between hyphenated words like "ill-educated" and "first-year student". Some people will fight to the death over which words should be hyphenated, but that is not my pet peeve.

In LaTeX and HTML, you can create a hyphen just by pressing the hyphen key, often in the upper-right corner of the keyboard.

A dash is a long line that can be used—often for long parenthetical explanations like this—as punctuation. This type of dash is sometimes called an em-dash. There is some controversy over whether there should be spaces around the dash. I prefer no spaces, but again, that is not my peeve.

In LaTeX you can create an em-dash by typing three hyphens---like this. In HTML, you can use the special sequence —. If you use another text preparation system, you should either find out how to create an em-dash or stop using them.

For more information on this important point of typography, see the Wikipedia page on Dash.

Other essays by Allen Downey are available here.