Em dashes

To indicate a break in the flow of a sentence—or an interruption—use an em dash, also known as a long dash. Don't put a space before or after it.

You can type the em dash character in various ways:

Press Option+Shift+hyphen.
Linux desktop environment
Enable the Compose key. (Instructions for doing that vary depending on your flavor of Linux; for examples, see Linux Keyboard Shortcuts For Text Symbols.) After the Compose key is enabled, you can create an em dash by typing the Compose key followed by three hyphens.
Alternatively, press Control+Shift+u, then let go of those keys, then type 2014, then press Return.
Note: These Linux options don't work if you're signed in to the Linux command line from a remote system using ssh or the like; you have to be in a Linux desktop environment.
Turn num lock on, then hold down the left Alt key and type 0151 on the numeric keypad.

Don't use an en dash (the shorter dash) or a hyphen in place of an em dash. The use of an en dash with spaces around it in place of an em dash is gradually becoming more common, but it's still not very widespread in the US in professional publishing; so far (as of early 2016), it's mostly used in Canada and a couple of other places. For now, just use the em dash.

En dashes

Don't use. Instead, use a hyphen or the word to. For more information, see the following sections:

Colons instead of dashes in lists

Another common but nonstandard construction is to use an em dash, an en dash, or a hyphen surrounded by spaces to separate an item and its description. Instead, use an HTML description list (<dl>) or, in some cases, a colon or period.


Not recommended: Example - This is an example.

Better: Example: This is an example.

Recommended for a series of items:

    <dd>This is an example.</dd>
    <dt>Another example</dt>
    <dd>This is another example.</dd>

Not recommended: Appendix A - My First Appendix

Recommended: Appendix A: My First Appendix