What's Best for SEO? StackOverflow.com style "domain.com/91512/some-trimmed-text" or "domain.com/91512_some-trimmed-text"
Use dashes - Google treats dashes as separating words, but underscores are considered part of a word. Cm.http://www.codinghorror.com/blog/archives/000574.html .
source to share
These tricks are good for 1 week than they change. All SEO materials are not based on a written rule. This is very suggestive, and between SEOs they don't really agree, so that a number written as a directory or before an underscore doesn't really have a better way. Of course, it's better to have a name the way SO works for indexing, but for how to organize the folder / files, it doesn't matter (of course, some SEOs will say different and this same guy will change his faith in 1 month ...).
source to share
As of last August, Matt Cutts still said that dashes were better than underscores , but it was hinted that they would eventually be handled the same.
Most SEOs consider Matt the leading expert in the field and the main, albeit unofficial, representative of Google to the SEO community.
But the question really was about underscore and forward slash. I would say there isn't much of a difference, but would suggest a third alternative that is fairly common: domain.com/91512-some-trimmed-text. We use this a lot in Rails applications because Active Record can use the table ID as if the next row did not exist.
source to share