em-dash / en-dash / hyphen

These are important distinctions to make since I use smart punctionation in pandoc. Examples taken from this answer on english.stackexchange.com.

em-dash

In pandoc use triple dashes, ---.

An em-dash is typically used as a stand-in for a comma or parenthesis to separate out phrases—or even just a word—in a sentence for various reasons (i.e. an appositive). Examples where an em-dash should be used:

• School is based on the three R’s—reading, writing, and ’rithmetic.
• Against all odds, Pete—the unluckiest man alive—won the lottery.
• I sense something; a presence I’ve not felt since—

en-dash

in pandoc use double dashes, --.

An en-dash is used to connect values in a range or that are related. A good rule is to use it when you’re expressing a “to” relationship. Examples where an en-dash should be used:

• in years 1939–1945
• pages 31–32 may be relevant
• New York beat Los Angeles 98–95

hyphen

In pandoc use a single dash, -.

A hyphen is used to join words in a compound construction, or separate syllables of a word, like during a line break, or (self-evidently) a hyphenated name.

• pro-American
• cruelty-free eggs
• em-dash
• it’s pronounced hos-pi-tal-it-tee
• Olivia Newton-John