Dashes and hyphens
Dashes and hyphens aren't interchangeable. Follow these guidelines to help you use them the right way, in the right places.
Em dashes. Use to set off or emphasize parenthetical phrases.
En dashes. Use in ranges of numbers and dates, in negative numbers, and as a minus sign. Use to connect compound modifiers under specific conditions.
Hyphens. Use to join words and connect prefixes to stem words. Don't use two hyphens in place of an em dash.