Separating words in your URLs
When you are creating your URLs how should you separate your words? Matt Cutts from Google has some advice. Cutts recommends using dashes instead of underscores to separate the words in your URLs.
While you may not actually be penalized for using underscores, they were once commonly used among spam websites and may still be valued less in Google's site assessment. So be sure to follow Matt Cutt's advice about avoiding underscores and follow our advice about how many hyphens to put in your URL and you will have taken 2 big steps in optimizing your URL.