There are at least three different dashes in traditional typesetting:
A hyphen is a short horizontal line used in (of course) hyphenated words
An en-dash is a slightly longer line usually used between numbers to indicate a range
An em-dash is an even longer line, used to indicate a pause in the flow of words, or perhaps an in interruption in speech.
hyphen: God the all-terrible
em-dash: ...when there had been enormous casualties on both sides—but before the United States entered the war in 1917.
en-dash is unicode 8211, html entity –
em-dash is unicode 8212, html entity —
In case you're wondering about the names, the en-dash is traditionally the width of a letter n, and the em-dash is traditionally the width of a letter M.
For much more on dashes
Originally Posted by AlexBell
Thanks, Harry. I'll fix the first two as soon as possible, but I'll have to do some research on the hyphen/em-dash problem. I'm not even sure at the moment what an em-dash is, nor how to produce one.