Non-Designer’s Type Book, The, Second Edition

Em Dashes

Text within parentheses is like whispering ; text within commas is an average statement; text within em dashes is more emphatic. The example below illustrates this concept.

Use em dashes to set off a phrase that has a lot of commas in it — like this, and thus, and so—to avoid confusing the reader.

Or mark an abrupt change in thought or sentence structure—I learned this yesterday—with an em dash.

Em dashes are set with no space before or after the dash. This bothers many people, though, because the dash tends to bump into the letters. So add a tiny bit of space on either side by kerning (see Chapter 14 on Kerning). But if you insert an entire word space before and after the dash, you exacerbate the interruption in the flow of text. ...