Google’s Gary Illyes reiterated that using hyphens as URL delimiters is still best for SEO purposes than using underscores as URL delimiters. why? Gary explained, “We recommend dashes because underscores don’t easily segment them.”
This came out around 17 minutes into the latest Search Off The Record podcast. Here Martin Splitt says: I don’t know, something.something/8907d12. And I, yeah, it’s not easy to remember. But that’s the “mobile_friendly-test” or something like that. It’s like, “Hmm!”, but you said there’s a difference, Gary.
Gary replied: The internet recommends dashes because what people write has underscores in them that can’t be easily separated by underscores. “
Here’s the embedding:
There is now a lot of history about comparing underscores and hyphens in URLs, and what Google has said about them before. In 2007, Google’s Matt Cutts dictated the use of hyphens/dashes over underscores, making it clear that Google did not say they were treated equally. He said in 2017 that he wanted Google to treat underscores as delimiters, but that didn’t seem to work at the time. In 2016 John Mueller said that underscores and dashes are irrelevant.
This is the latest from Google, so I’m assuming that’s okay. We recommend using hyphens/dashes over underscores to separate words in URLs.
One big caveat – never change an existing URL just to add a hyphen – it’s a horrible idea.
forum discussion at twitter.