An en is a typographic unit, half of the width of an em. By definition, it is equivalent to half of the body height of the typeface (e.g., in 16-point type it is 8 points). As its name suggests, it is also traditionally the width of an uppercase letter "N".
The en dash (–) and en space ( ) are each one en wide. In English, the en dash is commonly used for inclusive ranges (e.g., "pages 12–17" or "August 7, 1988 – November 26, 2005"), and increasingly to replace the long dash ("—", also called an em dash or em rule). When using it to replace a long dash, spaces are needed either side of it – like so. This is standard practice in the German language, where the hyphen is the only dash without spaces on either side (line breaks are not spaces per se).
ensp and ndash. Encodings:
- en space: U+2002 EN SPACE (  · UTF8:
- en dash: U+2013 – EN DASH (– · UTF8: