Em dashes and en dashes (— vs –)
There are two types of dash. The en dash is approximately the length of the letter n, and the em dash the length of the letter m.
- The shorter en dash (–) is used to mark ranges.
- The longer em dash (—) is used to separate extra information or mark a break in a sentence.
The en dash is sometimes also used in the same way as an em dash; in this case, it takes a space on either side.
Make sure not to confuse dashes with shorter hyphens (-), which are used to combine words (as in well-behaved or long-running). A hyphen should not be used in place of a dash.
The em dash: marking a break in a sentence
Em dashes can be used in pairs to mark off additional information that is not essential to understand of the sentence. Here they function similarly to parentheses or a pair of commas. Don’t put a space on either side of an em dash:
An em dash can also be used to mark a break in a sentence in place of a semicolon or colon. In this context, dashes are often used for emphasis or to signal a change in tone:
Note, however, that dashes used in this way are considered more informal than other punctuation marks, so should be used sparingly and selectively in academic writing.
The en dash: marking a range
The en dash is used to indicate a range of numbers or a span of time. You can read it as representing “to” or “through”:
Using en dashes in place of em dashes
You might also see an en dash used in the same way as an em dash, especially in less formal writing. In this context, unlike the em dash, the en dash takes a space on either side:
This usage of the en dash is especially common in British English, while the em dash is more prevalent in American English.
If you choose to use en dashes in this way, make sure to do so consistently. A common mistake is using both forms in the same text or spacing the punctuation incorrectly:
- Jeff Bezos–who is the founder, chairman, CEO, and president of Amazon — is one of the richest people in the world.
- Jeff Bezos—who is the founder, chairman, CEO, and president of Amazon—is one of the richest people in the world.
- Jeff Bezos – who is the founder, chairman, CEO, and president of Amazon – is one of the richest people in the world.
2 comments
Lou Benders
June 15, 2015 at 5:25 PMDear Dorothy,
Writing guidelines on when to use a hyphen is definitely a good idea!
In your case carbon-based is indeed correct. This is a compound adjective, just like well-known, good-looking, bad-tempered, carbon-neutral and custom-built.
Most compound adjectives are hyphenated and some are not. Sometimes hyphens are used in such adjectives to avoid that the meaning becomes ambiguous. This is the case with '100 year old men', which could be referring to 100 men that are a year old, or to men that are 100 years old.
However, whether you should use a hyphen or not, is not always clear. Thus, this is some food for thought!
We will definitely think about writing an article on the subject!
dorothy de kok
June 3, 2015 at 5:54 PMHow about some guidelines on when to use a hyphen and when not? e.g. is it carbon-based material or carbon based material? I go with the first one, but there is nothing here to support my opinion.
Really love your articles!