On the Use of Dashes
There are four kinds of dashes. From shortest to longest, they are:
- Hyphen
- En dash
- Minus sign
- Em dash
Hyphen
See the section on Hyphens.
En Dash
Technically, the width of the small letter n. Represents the word “to” or “through”:
1941–1945, 45–48°
Minus Sign
Technically, the same width as other arithmetic operators (in the typographic world). On most keyboards, the minus sign is the same width as the hyphen character; so, don’t worry about it.
-4°, -10 points
Em Dash
Technically, the width of the small letter m. Represents a break in thought, usually for emphasis:
Driving at night—especially in the rain—can be dangerous and requires more attention than daytime driving.