What is ndash?

Answer 1

An en dash is a mark of punctuation, like a hyphen, but longer. A hyphen is very short, an em dash is long, and an en dash is in between.

"En" is a measure of size. An en dash is half the width of an em dash. They are named for the capital letter M, which is the widest letter in a typographic font and thus sets a standard of the font, and the capital letter N, which in traditional type measure is half that width. Ens and ems can also measure spaces. For example, a bulleted list might be set with an em space after each bullet and before the start of text.

In use, an en dash is most commonly used for ranges such as with numbers and years. You might see the dates of a person's life listed as, for example, 1875-1960, meaning born in 1875 and died in 1960. In proper typography, that dash between the dates would be an en dash and not a hyphen. Likewise, a range of ages (children 6-8 years old), grades (K-12), sizes (fits size 9-10), and so on would normally be separated by an en dash.

Other uses that occur in print are typically more subtle and probably not necessary to understand unless you are interested in publishing conventions.