Use hyphens or underscores to separate words in URLs

Just like your domains, you should separate words in your URLs with hyphens (-) or underscores (_). Hyphens are better, but outside of the domain, underscores can work. Hyphens work better because many search engine spiders recognize hyphens as the end of a word, but see underscores as part of the word. Also, underscores can be seen as a space by your customers (because the underline of the link and the underscore merge together), and they will then get frustrated if they try to type the URL with a space and can't get to the page.