There are a number of version control systems available. Originally there was RCS, which was suitable for individuals, but not really suitable for groups of people. It evolved into CVS, which worked pretty well for years, and then Subversion came along, making a better CVS than CVS itself. At the same time, there were a number of other version control systems that were becoming popular that went from a central-repository style to a distributed-repository style. Git is one of these and has proven to be quite popular.