In the last lesson, we took a deeper look at commas. In this lesson, we will explore the difference between hyphens, en dashes, and em dashes.
Hyphens
A hyphen connects two words that are closely related and are acting as a single word. For example:
Two-thirds of survey respondents said they needed additional training.
This number is toll-free.
However, in some cases, you only connect the words with a hyphen when they are acting as an adjective modifying the word that follows them:
This architecture supports high availability when traffic increases.
(âavailabilityâ is a noun, and âhighâ is an adjective modifying it)
To handle traffic spikes, design a high-availability architecture.
(âhigh-availabilityâ is a compound adjective modifying âarchitectureâ)
Next, you check in your files.
(âcheckâ is a verb, âinâ is an adverb modifying âcheckâ)
The server sends a check-in notification.
(âcheck-inâ is a compound adjective modifying ânotificationâ)
Words that are hyphenated often evolve over time to become open compounds (that is, they have a space instead of hyphen). âOpen sourceâ is an example of an open compound:
This software is open source.
This open source software is free to use.
(No hyphen between âopenâ and âsourceâ)
And eventually, they may even become a single word. For example, âemailâ evolved like this:
Electronic mail -> e-mail -> email
âLog inâ is still two words when itâs a verb:
You can now log in to the application.
But itâs a single word when it acts as an adjective:
Your login information was sent to your email address.
Note: Why wouldnât you say âYou can now log into the applicationâ? Arenât you supposed to combine âinâ and âtoâ when theyâre next to each other? In cases like âLook into this for meâ, the answer is yes. But in this example, âlog inâ is a phrasal verb, meaning that the verb âlogâ and the adverb âinâ must go together and act as a single verb. Therefore, if you combined âinâ and âtoâ to make âintoâ, you would be splitting the âlog inâ phrasal verb in half, and âlogâ would be sad that âinâ ran off with that scoundrel âtoâ.
The Microsoft Writing Style Guide (and some other style guides) instructs us NOT to use hyphens after â-lyâ adverbs:
These are often-asked questions.
These are frequently asked questions.
(No hyphen after an â-lyâ adverb)
Irritating side note: Some grammar guides say you DO hyphenate after an â-lyâ adverb IF the second word in the compound is the past participle. In this case, âfrequently-asked questionsâ would require a hyphen, since âaskedâ is the past participle of the verb âto askâ, whereas âfrequently upsetting incidentsâ would not use a hyphen, because âupsettingâ is the present participle (not the past participle) of the verb âto upsetâ. Confused? Donât be, because weâre going to ignore that stupid rule and stick with the Microsoft Writing Style Guide!
Dashes
There are two types of dashes: en dashes and em dashes. En dashes are longer than hyphens but shorter than em dashes. Hereâs what they look like:
‐ hyphen
â en dash
â em dash
En dash
En dashes are uncommon. They connect two things that are related to each other by distance or time, essentially replacing the word âtoâ. For example:
Take the San FranciscoâNew York flight.
I read this in the MayâSeptember issue of the magazine.
This certificate is valid 2017â2018.
Note: In this last example, you can replace the en dash with âfromâ and âtoâ:
This certificate is valid from 2017 to 2018.
OR
This certificate is valid 2017â2018.
But NOT:
This certificate is valid from 2017â2018.
To type an en dash, see: https://www.howtotype.net/symbol/en-dash/
Em dash
The em dash is longer and is more common than the en dash. It sets off and emphasizes additional information in the sentence and can be used in place of commas, a colon, or parenthesesâas I just did in this sentence. For example, consider the difference in emphasis in these three sentences:
When the car was finally delivered three months after it was ordered, she no longer wanted it.
When the car was finally delivered, three months after it was ordered, she no longer wanted it.
When the car was finally deliveredâthree months after it was orderedâshe no longer wanted it.
The second example uses commas to offset and put extra emphasis on the phrase. The third example uses em dashes to emphasize it even more, indicating how irritating it was that it took three months for the car to arrive.
Hereâs an example of an em dash replacing a colon:
The white sand, the warm water, the sparkling sunâthis is what brought them to Hawaii.
To type an em dash, see: https://www.howtotype.net/symbol/em-dash/
Summary
Hyphens connect two words that are closely related. En dashes connect two things that are related by time or distance and replace the word âtoâ. Em dashes set off a part of the sentence to give it extra emphasis.
Additional resources
- http://www.thepunctuationguide.com/hyphen-and-dashes.html
- https://www.khanacademy.org/humanities/grammar/punctuation-the-colon-semicolon-and-more/hyphens-dashes-and-ellipses/v/dashes
- https://www.khanacademy.org/humanities/grammar/parts-of-speech-the-modifier/adjective-order-and-commas-with-adjectives/v/commas-and-adjectives
đAssignment
- Write two examples of using a hyphen to create compound adjectives.
- Write three versions of the same sentence showing how you would offset part of it with parentheses, commas, and em dashes.
- Write a sentence using an em dash in place of a colon.