Here is a little note about dashes and hyphens and how WordPress handles them.

WordPress can do some clever things with typography — and some of these it does as standard. Look, it’s just done one of them in the previous sentence.  I typed two hyphens (or minus signs) into the editor and WordPress has automatically converted that into an em-dash. WordPress will also change a hyphen into en-dash when used in the correct place.

Not only does this make the text read better, and satisfy the small but passionate group of people who really care about these things, it is also really useful when writing posts in plain text or markdown. So here is a little reference of what to type to get different dashes:

Hyphen

one--two

= one–two

one - two

= one – two

En-dash

one-two

= one-two

Em-dash

one -- two

= one — two

More about this can be found in this post by Mark Jaquith from June 2012.