The hyphen you can insert with the key next to the zero on your keyboard is an ambiguous character suffering from an identity crisis.
It can't decide if it's a hyphen
-, a minus
−, an em dash
— or an en dash
The Unicode specification describes the key as a hyphen-minus and defines very specific replacements for its use.
Use it to insert a hyphen, but never for a minus or a dash, since it does not have the correct width for either, or the vertical position for the latter.
Neither an em dash nor an en dash should be confused with the hyphen, which has the following functions:
The modern trend is away from hyphenation, and to eliminate the hyphen after a prefix.
Hyphens are always required with the following prefixes:
Permanent compounds tend to become solid, and temporary compounds tend to be hyphenated only when necessary to avoid ambiguity.
|hyphen character||used in place of the hyphen-minus when a hyphen is exactly the desired character||‐||‐|
|non-breaking||does what its name implies||‑||‑|
|soft hyphen||indicates where a word may be broken at the end of a line||­||ab|
|hyphen point||used in dictionaries to separate syllables||‧||‧|
|hyphen bullet||a version of the hyphen character||⁃||⁃|
|z1 double oblique||punctuation||⸗||⸗|
|z1 with diaeresis||punctuation||⸚||⸚|