Having to do with writing, understanding the difference between a hyphen and a dash is necessary--many persons don't. Writing informally, a dash is to show pause in thought within a sentence, as I used in this paragraph. A hyphen connects words or numerals to unify them to complete, or make a new a meaning. Examples of this unification are: a 'phone No. 123-456-7890, or in the case of two words: Freja was born in the year nineteen hundred fifty-eight.; the fast-talking bird; three words: The out-of-state couple came here to marry.

 

With the proper use of the hyphen, you can convey your exact meaning: The fine-ground coffee tastes good.  Without the hyphen (The fine ground coffee tastes good) the sentence meaning could be construed as reference to quality, instead of the coarseness of the grind. The finely ground coffee... could be written with no hyphen necessary. If you wanted to emphasize the quality of the coffee, using the same words, you would write with a comma: The fine, ground coffee tastes good.   

 

Again, notice the confusion: The fast talking bird flew out the window. Is the bird a fast talker, or a fast flier? The hyphen should be used where the intended meaning would be difficult or impossible for the reader to understand without it. The fast-talking bird flew out the window. With the use of the hyphen, it's clear to understand the intended meaning--a bird that speaks quickly. Or, a bird that flies fast:  The fast, talking bird flew out the window.  The placement-choice of the hyphen dictates the meaning. Notice my unification of placement-choice for clarity.

 

The line of a dash symbol is twice the length of the hyphen. As there is no dash on the typewriter or computer keyboard, you must use two strokes of the hyphen key to make a dash symbol when typing, i.e.--.

 

Richard Stuart Otto, 16 Dec. 2004