What exactly is Software Configuration Management?
In a nutshell, SCM is a system of methods used to control and manage a software development project. The SCM process activities are designed to control change by identifying the likely changing work products, establishing relationships among them, defining mechanisms for managing different versions of these work products, controlling the changes imposed, and auditing and reporting on the changes made.

Various types of work products may be managed or versioned in SCM: documents, software code, design models, etc.

What is the purpose of SCM?
Generally, there are nine goals of effective SCM. Table A describes them.

SCM process concepts
Your project has specific objectives and requirements that will be reflected in the SCM process you implement to manage change. The following are some process concepts vital to any SCM implementation.

Track change packages
Each file in a code line has its own revision history. But each revision is only useful in the context of a set of related files. In order to identify all changed source files, you have to track change packages, which are sets of files related by a logical change.

Track change package propagations
Tracking change packages makes it easier to propagate logical changes from one code line branch to another. But propagating change packages across branches is simply not enough. You must keep track of which change packages have been propagated, which are pending propagation, and which code line branches are probable donors or recipients of propagation.