What is it?
In computer programming and software engineering, developers make changes to software as they are creating it and maintaining it. Source code management or revision control is used to keep track of the various changes made to every iteration of the source code. A repository or tool such as GitHub can be used to manage the software in a controlled way. Tools like this also support collaborative development practices.
References
OpenHIE reference software can be used to see how this OpenSource software is managed.