Printer's dashes, also known as en and em dashes, are punctuation marks used to indicate a break in a sentence or to set off parenthetical phrases. The en dash (ENS) is slightly longer than a hyphen and is used to indicate a range of values, such as dates or numbers. The em dash (EMS) is the longest of the three and is used to indicate an abrupt change in thought or to set off a phrase for emphasis.