I regularly get asked whether dashes or underscores in URLs are better for search engine optimization.
ie which of the following is best – www.problogger.net/is-this-better or www.problogger.net/is_this_better ?
For the past six or so months I’ve leant towards dashes instead of underscores – but it’s always been a ‘best guess’. Today in reading Matt Cutt’s blog I think I’ve made a good decision as he writes - ‘I often get asked whether I’d recommend dashes or underscores for words in urls. For urls in Google, I would recommend using dashes.’
He goes on to explain why – but I think you’ve already got the answer. For Google Dashes are best.