It used to be that google preferred the hyphen (-) to the underscore (_) when it came to page names.
So www.yourdomain.com/page-name-here.html was seen more favourably than www.yourdomain.com/page_name_here.html when it came to listings and positioning.
That’s all changed, and now it makes no difference which one you use – Google treats them both the same.
(We’d recommend sticking to one or the other though, rather than mixing them, for the sake of clarity)
Fair point. However, from a usability perspective hyphens are a simpler character to type. A few years ago I carried out a brief test of users and found that over half of then typed a hyphen when attempting to type an underscore.
Absolutely – although don’t get me started on domain names with hyphens in them