The Difference Between Dashes and Underlines in SEF URLs
By P.J. Swesey
You may have heard that Google and other search engines prefer that you use dashes or hyphens (-) instead of underlines or underscores (_) as word separators in your URLs. Google actually recommends that you use dashes or hyphens when creating search engine friendly or search engine optimized URLs instead of underscores. Here’s why.
Google sees underlines or underscores as an actual underline character, so a PHP programmer searching for “similar_text” would get results about the PHP function similar_text() instead of all search results for “similar text”. So the hyphens in SEF URLs tell Google that each word is a separate word, while underlines tell Google that your URL is one long word.


