I never really understood the difference between using the hyphen, the en dash – and the em dash —. I found this article from list apart which explains it really well.
In a nutshell the basic uses are:
- Hyphen used to join two compound words (re-read)
- En dash used for a range of things such as dates, numbers or instead of to (2–9)
- Em dash used when writing a break in thought—like now!