Sometimes you might not detect the bug for a long time after some modification, at that time you may use CVS. With the help of concurrent versions system, you can easily retrieve old version to catch exactly what changes caused the bug.
CVS stands for Concurrent Version System. It is an open-source SCM designed to manage different versions of the same project in a specialized repository. You can simply record the history of your source file using CVS. This system stores only the differences between the versions, instead of saving every version of each file.
Why You Need CVS?
Think that if you are working in the group of people on the same project, then CVS merges the work when each developer has done their work. CVS repository stores a copy of all the directories and files that are under version control.
Commonly, you don’t have rights to access the files in repository directly, but you may use its commands to get a copy of the files into a working directory and then continue the work on that copy.