hyphen(-), dash(—), minus(-)
What do I use when? and does it really matter? And what's their origin, why did people think they needed another very similar sign?
The minus and hyphen sign are the same thing. A hyphen is a short, single-character line which connects word parts (i.e. ice-cream). A dash is a longer line—double the length of a hyphen—which indicates a break or an interruption in the thought. Dashes are used to set off part of a sentence. Unlike parentheses, which tend to minimize, dashes tend to emphasize the set-off text (i.e. There was only one person suited to the job—Mr. Lee).
I am not sure of their origin.