Hyphens, en-dashes and em-dashes are frequently used punctuation marks that are just as frequently misunderstood. All three marks are essentially horizontal lines, though their lengths vary. These three different marks have very different purposes, and using a hyphen to do an m-dash’s job is just as much of a punctuation error as using a question mark in place of a comma.

Hyphens, En-dashes and Em-dashes