If you’re like most people, you may be confused about the difference between a hyphen (-) and a dash. This may even be the first time you’ve heard that there are actually two types of dashes: an en dash (–) and an em dash (—). What’s the difference between these three punctuation marks? We’re going to walk though it today.
As you can see, hyphens, en dashes, and em dashes are all horizontal lines that vary in length. Hyphens are the shortest, en dashes are a bit longer, and em dashes are even longer. Here’s a trick for remembering the difference between the two dashes: En dashes are named after the letter “N” (“en” = “N”) because en dashes were the same width as a typesetter’s letter “N” (when text was printed by pressing metal blocks onto paper). Em dashes are named after the letter “M” (“em” = “M”) because em dashes were the same width as a typesetter’s letter “M.”
Now that we know how these punctuation marks differ in appearance, we can talk about how we use them in sentences.
Hyphens are used to form compound words. Compound words are terms that are made up of multiple words that together express a single idea (e.g., “self-esteem,” “to nickel-and-dime,” and “follow-up”). Of course, not all compounds contain hyphens; some are open compounds (e.g., “car wash” and “printing press”) and others are closed compounds (e.g., “bookstore” and “lifestyle”). However, many compounds do contain hyphens. Which ones? See these tips:
Compound nouns: terms made up of multiple words that describe a single person, animal, thing, place, or idea (e.g., “self-esteem” and “bookstore”). A good dictionary will usually tell you if a compound noun contains a hyphen.
Compound verbs: terms made up of multiple words that describe a single action (e.g., “to nickel-and-dime” and “to double-check”). A good dictionary will usually tell you if a compound verb contains a hyphen.
Compound adjectives: terms made up of multiple words that describe a single characteristic of a noun (e.g., “follow-up” and “high-quality”). Unlike compound nouns and verbs, a dictionary usually won’t tell you if a compound adjective contains a hyphen. Luckily, you can use the following rule to figure out whether or not you need to use hyphens in your compound adjective:
Use a hyphen when the adjective comes right before a noun
Leave the hyphen out when the adjective comes after the noun
“Practices that are evidence based”
Of course, to make our lives difficult, there’s an exception to this rule: no matter where the adjective is placed in the sentence, leave the adjective out if the first word in it is an adverb that ends with “-ly” (e.g., “quickly,” “slowly,” and “quietly”)
“Environmentally friendly programs”
“Programs that are environmentally friendly”
Note that a lot of people think they need to use hyphens to join words to prefixes (e.g., “co-” and “non-”). In most cases though, these hyphens aren’t needed. Take a look at these examples:
Again, there are some exceptions, so keep that hyphen in when you’re in one of these situations:
When the base word is capitalized (e.g., “post-Freudian”)
When the same vowel appears at the end of the prefix and the beginning of the base word (e.g., “anti-icing”)
When leaving the hyphen out would lead to misinterpretation (e.g., “re-cover” vs. “recover”; these are different words with different meanings)
We typically use en dashes in two key ways: to express number ranges and to represent a conflict, connection, or direction. For example, we could use an en dash when describing the number of people who attended an event:
“There were 500–600 people at the event.”
We could also use it to identify an academic or fiscal year:
“They added the course during the 2015–2016 school year.”
Many people use hyphens when writing number ranges, but the en dash is the correct punctuation mark in this case. You can insert an en dash in a Word document by clicking on “Insert” and “Symbol.” You can then select the en dash from the list of options.
Note that you don’t have to use en dashes when providing number ranges. For example, you could rewrite the first en dash example above like this:
“There were between 500 and 600 people at the event.”
What you don’t want to do, however, is combine these two approaches. The en dash essentially expresses the words “between” and “and” in this case, so if you use both the words and the en dash together, you’re being redundant.
We can also use an en dash to express a conflict, connection, or direction. Take a look at these examples:
“We watched the Jays–Red Sox game.”
“The Toronto–Amsterdam flight is delayed.”
The first sentence says that we watched a baseball game in which the Jays played the Red Sox; it tells us which teams were playing against each other. The second sentence says that the flight travelling from Toronto to Amsterdam is running behind schedule; it tells us the direction the plane flew in.
Now, you may be wondering how this way of using an en dash is different from using a hyphen to join words in a compound. Remember that compound words are formed when two or more words come together to express a single idea. When we use en dashes to describe conflicts, connections, or directions, on the other hand, the words retain their individual meanings. That is, “Toronto” and “Amsterdam” have the same meaning whether they’re joined together with an en dash or used in separate sentences; in both cases, they’re still two different places.
Of the three punctuation marks that we’re talking about today, em dashes are the most versatile of the bunch: they can replace commas, parentheses, and colons. Take a look at these examples:
Use a pair of em dashes instead of commas
“When the furniture finally arrived, almost eight months after they ordered it, James and Amy realized that it didn’t fit in their dining room.”
“When the furniture finally arrived—almost eight months after they ordered it—James and Amy realized that it didn’t fit in their dining room.”
Use a pair of em dashes instead of parentheses
“When she discovered that the billing records had been destroyed (shredded and deleted electronically), she immediately called her colleague.”
“When she discovered that the billing records had been destroyed—shredded and deleted electronically—she immediately called her colleague.”
Use a single em dash instead of a colon
“After months of deliberation, the jurors reached a unanimous verdict: guilty.”
“After months of deliberation, the jurors reached a unanimous verdict—guilty.”
As you can see, em dashes create a more noticeable or intrusive break in a sentence; they place more space between the part of the sentence that comes before the em dash and the part of the sentence that comes after it. For this reason, an em dash may be the best choice when you want to emphasize the part of the sentence that comes right after it.
In the furniture example above, the version with em dashes draws more attention to the eight-month delay than the version with commas does. If you wanted to emphasize how ridiculous it is that it took eight months for the furniture to arrive, an em dash would be the way to go. However, if you just wanted to make sure that the sentence included information about how long the furniture shipment took, it would make more sense to use commas. Similarly, in the verdict example, the version with the em dashes draws more attention to the guilty verdict than the version with the colon does. If a guilty verdict was expected or at least a clear possibility, it may make more sense to use a colon. On the other hand, if a guilty verdict wasn’t expected and the outcome of the trial is a surprise, an em dash may be a better tool for expressing this.
Have questions about the difference between hyphens, en dashes, and em dashes? Leave us a note in our comments section below and we’ll get in touch. Your question may even inspire one of our upcoming posts!
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