Use an em dash (—) to set off a parenthetical phrase with more emphasis than parentheses provide. Don’t add spaces around an em dash.
Use one em dash on each side of a phrase embedded in a sentence.
The information in your spreadsheet—numbers, formulas, and text—is stored in cells.
Use one em dash to set off a phrase or clause at the end of a sentence.
If you're not sure about the details, look at the illustrations in the wizard—they can help you figure out what type of connection you’re using.
Don’t use an em dash:
In place of a bullet character in a list.
To indicate an empty cell in a table.
Don’t capitalize the first word after an em dash unless the word is a proper noun.