From : Blog Entry>>ILTA’s Blog Entry
Em dash vs. En dash vs. Hyphens Em dash (—): Sets off words, phrases, clauses, or short sentences Functions as a substitute for a colon, a semicolon, or parentheses Mary’s sister—her only sister—moved to Chicago last summer. En dash (–): Used for numeric ranges, including page ranges Compound modifiers comprising terms of equal weight Attorney—client privilege Hyphens (-): Used to join two or more words that are used as a single noun Fact-finding Compound modifiers: [More]