Revision control (also known as version control, source control or (source) code management (SCM))

the management of changes to documents, programs, and other information stored as computer files. It
is most commonly used in software development, where a team of people may be changing the same
files. Changes are usually identified by a number or letter code, termed the "revision number", "revision
level", or simply "revision". For example, an initial set of files is "revision 1". When the first change is
made, the resulting set is "revision 2", and so on. Each revision is associated with a timestamp and the
person making the change. Revisions can be compared, restored, and with some types of files, merged.