That chart shows how many users each “github organization” has attracted to GitHub. This is a great metric for GitHub to measure and promote, but it doesn’t account for the whole open source world. For example it doesn’t include top communities like Android, Chromium, GNU, Mozilla, nor the the Apache or Eclipse Foundation, and other projects that choose to run most of their activities outside of GitHub.

Thanks for the post and analysis!

I also published a spreadsheet that looks into what type of events that chart and query are counting: