The Popularity Score
The internet is a battle field. All projects cry for attention. The successful ones distinguish themselves by great content, superb marketing, thorough documentation.
The popularity score is an indicator on how popular the repository is in the GitHub community, but also in the internet in general. The rating is a good indicator to know wether you are dealing with a niche product or a mainstream repository.
Popular repositories attract many users who potentially already identified most of the bugs and requested quite a few reasonable features. As a user you can expect a high level of maturity in the repository.
The popularity score takes the following indicators into account:
GitHub: # of forks
GitHub: # of watchers
GitHub: # of stargazers
Bing: # of search results for project
All indicators are retrieved from GitHub or Bing.