What does Google say?
Google searches for relevant content based on keywords found in titles, urls, images, descriptions, and page content. Upon abbreviated research in answering the question about the benefit of using hyphens vs underscores in file naming and slugs in your website url, the definitive answer, according to Matt Cutts, Search Quality team member at Google, is to use dashes.
- Ashley-Cameron = Ashley Cameron (correct)
- Ashley_Cameron = AshleyCameron (incorrect)
- AshleyCameron = AshleyCameron (incorrect)
Why? Please explain.
This quick three and a half minute video more thoroughly explains how Google joins words with underscores (e.g. can_you_read_me_now) and reads hyphens as separate words (you-can-read-me-now). The video was recorded in 2011; however, the information remains relevant today.
Do I need to rename all of my existing site files?
If your website is already using underscores primarily, it’s far too time consuming to go through and rename them for a minor search engine rank increase. Put this new knowledge in your toolbox for the future or consider renaming titles, indices, links, images, alt descriptions, etc if you’re undergoing a major overhaul.
More importantly than renaming
Make sure you are not combining words into an unseparated string. The separate words are indistinguishable by Google.