Mr. Meyer writes:
For the uninitiated: Github helps programmers (and teams of programmers) keep track of different versions of code, an important task when hundreds of people might be editing the same code base or piece of software. It can compare two different code snippets and tell you what the differences between them are, and who made those changes. It can tell you how all the changes in a project compare to each other. And it can, in the service of that one, huge, change-tracking feature, do a ton of other things too.* The New Yorker published an online introduction to the service earlier this month.
So, Github is a singular phenomenon in the world of code.
Excuse me, Mr. Meyer, but version control has been around since the days I was coding in DOS, 25 years ago. Did you fail to do a simple search on wikipedia for version controls systems?