An en dash is shorter than an em dash and longer than a hyphen. En dashes represent ranges and certain word linkages. There are no universal uses of the en dash; a hyphen often replaces it.
The Chicago Manual of Style and the Merriam-Webster Guide to Punctuation suggest using an en dash for ranges.
The Publication Manual of the APA and the Merriam-Webster Guide to Punctuation suggest using an en dash between modifiers of equal weight.
The Merriam-Webster Guide to Punctuation suggests using an en dash like a hyphen to link modifiers in cases where one or both modifiers are made up of multiple words.
See Also: Hyphens