So, you already know that including your keywords in your URL is an SEO best-practice and a very strong driver of good search engine rankings. But what if you have more than one keyword in your URL? How do you separate them? Should you push them together, use dashes, underscores, or other delimiters?
The short answer is to use dashes to separate keywords. Matt Cutts, Google's head of web spam and SEO king, has come out and said this explicitly so I'll leave it at that. Plus, I agree that it's more readable from a user perspective as well.