Em dashes

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.
  Example
  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.
  Example
  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.