Then what else is it? There's a strong focus on community building (i.e. push/pull requests) (social), and those people create the bulk of the site's content (m

Then what else is it? There's a strong focus on community building (i.e. push/pull requests) (social), and those people create the bulk of the site's content (media), which in turn draws in outside users and encourages them to sign up and through a combination of sharing content (i.e. forks/clones) and new content (i.e. new projects). Of course it's social media. The difference is literally only in terms of what the media in question is.