Reindeer aside, many people (including a shocking number of writers) don’t realize that there are several different types of dashes, each with a different usage.
Keeping these straight will keep readers from rolling their eyes at you.
English has three different “dashes,” each a slightly different length: the hyphen ( – ) is the shortest; the em dash ( — ) is the longest; and the en dash ( – ) is in the middle. The strange terms for the dashes are because they were exactly as long as the width of two letters (m and n, respectively) in typesetting.
Hyphens are properly used between the parts of a compound adjectives (like “wild-goose chase,” or “long-term contract”) or name (like Rolls-Royce or Lloyd-Smith), or between the syllables of a word, especially when you want to break the word at the end of a line of text. Of course, all computer programs hyphenate sentences automatically, so that’s no longer an issue
The Em Dash ( — )
This is the dash to use in sentences when you want to express a parenthetical thought but don’t need as long a break: “The painting—which was reminiscent of his Blue Period works—was stolen in a daring robbery in 2003.” It’s used in writing and printing to indicate a break in thought or sentence structure—to introduce a phrase added for emphasis, definition, or explanation, or to separate two clauses. A longer pause might require parentheses instead of dashes, as in, “The painting (whose moody depiction of the night sky has been the subject of countless essays) was stolen in 2003.”
The En Dash ( – )
The least-used of the three is the en dash. It’s used in writing or printing to connect continuing or inclusive numbers (like ranges of dates, as in “1880–1945”), or to connect elements of a compound adjective when either of the elements is an open compound (as in “Princeton–New York trains”).
Word Processor Crimes
All keyboards have a dedicated hyphen key. But you’ll need a few tricks to get the dashes right.
To insert an em dash:
- On a Mac, hold down Shift-Option and press the hyphen key.
- In Windows, hold down Alt while typing 0151 on a dedicated keyboard. Or choose Choose Symbol from the Insert menu, click the Special Characters tab, highlight the em dash, and click Insert.
To insert an en dash:
- On a Mac, hold down Option and press the hyphen key.
- In Windows, hold down Alt while typing 0150 on a dedicated keyboard. Or choose Choose Symbol from the Insert menu, click the Special Characters tab, highlight the en dash, and click Insert.
However, among MS Word’s talents is the fact that it will happily convert your hyphens to em dashes and en dashes automatically. The crime is that to create an em dash, you type your text, do not hit the spacebar, hit the hyphen key twice, again don’t hit the spacebar, and continue typing your text. If you want to create an en dash, you use spaces before and after your hyphens.
The crime is that in properly set type, neither dash has spaces before or after them, but most typists, remembering the bad old days of the typewriter when double hyphens had to stand in for the em dash, rather automatically insert spaces. This makes your text look like this – rather than this—which is terrible on so many levels.
Most of the time in your writing, you’ll want to use an em dash to help punctuate your thoughts and phrases. Let Word do it automatically but keep your fingers off the spacebar!