Believe it or not, there are three main types of dash, denoted by slightly different lengths and uses. The first and shortest kind is a figure dash, so named because it’s the same width as a digit in most fonts. Fittingly, the figure dash is used when joining together a series of digits, like in a Social Security number or phone number.
Finally, the em dash (or “mullet") is the longest dash – twice the length of an en dash and as wide as the height of a capital letter (10 points high in 10 point font). Em dashes are most commonly used in the middle of a sentence – like parenthesis – to insert and draw attention to a related idea. They’re also used to show an interruption or abrupt halt in though, such a–
On of the most important thing to remember about dashes is they’re not hyphens. Though a hyphen is often identical to an en dash in many fonts, it serves it’s own unique purposes. For example, hyphens join together compound words like “mind-blowing,” “second-rate,” and “time-wasting.” They’re also affixed to prefixes when they precede proper nouns, like “un-American.” Finally, hyphens are used to connect syllables when a word is trun-
cated at the end of a line.
Hopefully, your somewhat-improved knowledge of dash-hyphen usage has filled you with grammatical glee or – at the very least – a newfound appreciation for your word processor’s autocorrect.