The em-dash is often typed as a double hyphen in copy. In printed material, use an em-dash—which has no space on either side. University typographical standards are to add a little “air” on either side of the dash, but not a full space.

The hyphen ‐ is a punctuation mark used to join words and to separate syllables of a single word. The use of hyphens is called hyphenation. Son-in-law is an example of a hyphenated word.

In Japanese, the double hyphen (ダブルハイフン, daburu haifun) is one of the symbols used to separate first and last names being written in katakana. For example, my name is Drew Mackie. I could write it in katakana as ドゥルー・マッキー, with the dot in the middle representing the separation between my first and last names.

A 'slash' and a 'virgule' are the same thing (/). They're just alternative names. A dash is either the em dash (long dash or 'mutton dash' —) or the en dash (short dash or 'nut dash' –). The long dash can stand in lieu of commas, paretheses or colons, each with slightly different effect.