Configuration management is essential when it comes to programming with a group. If you do not have some type of configuration management there is no way to ensure that all of the programmers working on a project or on the same version of the project. It is also impossible to ensure that there is no collisions when it comes to two programmers testing on the same blocks of code. When using configuration management you at least ensure that the programmers are able to test locally without getting in the way of the other programmers.
The image above is just a more complex flow chart of how configuration management is used. We can see it starts with planning. This would be debatably one of the more important steps as we would use this time to confirm what we are going to do with the other programmers and ensure when we update we are not going to affect other work. However the next four steps are essentially the process of the programmers working and updating their work and the cycle continues until the project is done.
I believe that github is the reason that git is so popular. Having a large repository of open source repositories is something that would have been uncommon back when github was first becoming popular. We can assume that there have always been other ways for programmers to collaborate with their work so using git is not something that is revolutionizing the way people work together, however having a place where you can access free use code whenever you need to is something that has changed to programming game.