Writers love em dashes as much as hunters love Swiss army knives. It’s not difficult to understand why. Like the utilitarian knife, em dashes are versatile tools. Once you find out about these handy dashes, you may fall in love with them too.
On computers, they’re easy to type—on a Mac, go for Shift+Option+Minus (-); on Windows use Ctrl+Alt+Minus (-).
What Is an Em Dash?
Em dashes differ from other hyphens and dashes not only in usage, which we will discuss shortly, but also in appearance. In fact, the em dash is named after its length—it’s about the same width as the capital letter M. Its alphabetical cousin, the en dash, is about the same width as the letter N. Figuratively speaking, the hyphen pulled the short end of the stick.
Use Em Dashes to Set Off Parenthetical Information
Em dashes are often used to set off parenthetical information. Using em dashes instead of parentheses puts the focus on the information between the em dashes.
For this usage, make sure you use two em dashes. Use one before the parenthetical information and one after it. Putting spaces before and after an em dash is a matter of preference; just be consistent. Consider the examples below for reference:
Use an Em Dash to Set Off Appositives that Contain Commas
An appositive is a small section of extra information that is inserted into a sentence for clarification. Commas are usually used to offset the appositive, but if the appositive contains one or more commas, adding additional commas would be confusing for the reader. When using an appositive that contains a comma, offset it with dashes, instead.
Use an Em Dash to Bring Focus to a List
When a sentence begins with an independent clause and ends with a list, you can use a colon between the clause and the list. When the list comes first, it’s better to use a dash to connect the list to the clause. This helps to take three potentially random things and focus them toward one idea, which is easier for the reader to process.
Use an Em Dash to Mark Sharp Turns in Thought
Em dashes can also signal an interruption or a sudden change in the direction a writer was heading with a particular sentence. This technique is best suited for creative or informal writing. If you use it in academic writing, you might look unsure of yourself. Consider the examples below:
Em Dash vs. En Dash
En dashes are slightly shorter than em dashes. They also have a different function. The two main uses of en dashes are to indicate number ranges and to act as a kind of super-hyphen for compound modifiers. Learn more about the difference between em dashes and en dashes here.