The hyphen (-) is a punctuation mark used:
- to form compound words (well-respected, forty-two, run-of-the-mill)
- to break up a single word be-
tween 2 lines of justified text
- after prefixes and before suffixes to avoid mispronounciation or misinterpretation (co-operation, re-creation v. recreation)
- to separate words into syllables or letters to indicate spelling (syl-la-bles, S-P-E-L-L-I-N-G)
The en dash (–) is wider than the hyphen. (Some fonts, such as Trebuchet, which is used throughout Knewance, render hyphens and en dashes as essentially indistinguishable characters.) Its width is defined as half the height of the font, which was the traditional width of the lowercase letter ‘n’. The en dash serves several purposes:
- To indicate ranges of numbers, dates, or times (pp. 184–187, Mitch Hedberg (1968–2005), 10:00–12:00). In these cases, the en dash can be read as the word ‘to’: ‘pages 184 to 187’.
- In scores or voting (Boston beat Chicago 47–40.)
- To signify a relationship between 2 things (Bose–Einstein condensate, Sydney–Los Angeles flight)
- In compound adjectives where one part is already hyphenated or consists of 2 words (hyper-threaded–land-grid-array processor, Revolutionary War–era)
On computers with Windows operating systems, an en dash can be typed with the Alt code Alt+0150.
The em dash (—) is twice as wide as an en dash; historically, it was as wide as a capital ‘M’.
- It takes the place of parentheses to demark an abrupt change in thought where a comma is too weak and a period is too strong. (‘Monkey brains—though popular in Cantonese cuisine—are not often to be found in Washington, D.C.’)
- In informal writing, it takes the place of a colon to introduce a logical consequence or explicitly list the members of a set. (I have 3 pets—a leafy sea dragon, a pangolin, and a puffin.)
- It can also be used to indicate that a speaker has been interrupted, or is too overcome with emotion to continue speaking.
The Alt code to produce an em dash is Alt+0151.