[s_m]

In the late 00's, SVN was the dominant version control system, but it had lots of pain points (eg reliant on remote server, lots of crappy little .svn directories, branching was difficult, very difficult to make a git repo for small projects etc) that Git resolved. At this time, hg and bzr were also on the scene, but Github quickly became incredible popular, for a few reasons - Sourceforce, the incumbent community home for open source, was a comparatively inferior user experience - Rails, which was a dominant OSS project in that era, was hosted there, and the Rails / Ruby community converged on GH as a result - Heroku was a trendy platform during this time, which at the time you deployed by `git push`-ing, so git knowledge was required to take advantage of it.