It's important to know how to use hyphens, en dashes and em dashes correctly.
A hyphen is used to separate two words that go together, such as in a compound adjective. For example:
The green-eyed gentleman.
An en dash should be used between the ends of a range, such as those of numbers or time periods. For example:
Page numbers 110–150.
An en dash can be entered with the alt code 0150.
An em dash is used in place of commas or parentheses to set a phrase apart from the rest of a sentence. For example: The partners—David and Alice—went to court.
An em dash can be entered with the alt code 0151. An en dash is half of the length of an em dash.