The em dash is perhaps the most versatile of punctuation marks. It can be used in sentences to create a strong break, to show emphasis, or to denote a change in thought. Depending on the context, the em dash can take the place of commas, parentheses, or colons. Many confuse the em dash for the slightly narower en dash or the even narrower hyphen.
The em dash can be created by holding down the ALT key and typing 0151 on the numeric keypad (right side of the keyboard). Macintosh users, press Shift-Option and the minus key at the same time.
The en dash is used to represent a span or range of numbers, dates, or time. There should be no space between the en dash and the adjacent material. Depending on the context, the en dash is read as “to” or “through.”
The en dash can be created by holding down the ALT key and typing 0150 on the numeric keypad (right side of the keyboard). Macintosh users, press the option and minus keys simultaneously.