Dash

A dash is a punctuation mark that is similar to a hyphen or minus sign, but differs from both of these symbols primarily in length and function. The most common versions of the dash are the en dash (–) and the em dash (—), named for the length of a typeface's lower-case n and upper-case M respectively.

Usage varies both within English and in other languages, but the usual convention in printed English text is:

• Either version may be used to denote a break in a sentence or to set off parenthetical statements – ideally with intradocument consistency. Style and usage guides vary, but often in this function en dashes are used with spaces and em dashes are used without them:

  [Em dash:] A flock of sparrows—some of them juveniles—alighted and sang.

  [En dash:] A flock of sparrows – some of them juveniles – alighted and sang.

• The en dash (but not the em dash) is also used to indicate spans or differentiation, where it may be considered to replace "and" or "to" (but not "to" in the phrase "from … to …"):

  The French and Indian War (1754–1763) was fought in western Pennsylvania and along the present US–Canadian border (Edwards, pp. 81–101).

• The em dash (but not the en dash) is also used to set off the sources of quotes:

  "Seven social sins: politics without principles, wealth without work, pleasure without conscience, knowledge without character, commerce without morality, science without humanity, and worship without sacrifice." —Mahatma Gandhi

https://en.wikipedia.org/wiki/Dash