Version control systems allow you to keep track of changes you have made to your data files in an efficient manner. You can think of it as a better backup.
Version control systems have been used by software developers for decades to keep track of what they have done and enable steps to be undone without manually trying to keep track of it all themselves. But it doesn't just work with code - any document/file can be stored in a version control system though it works best with text-based files.
There are many different types of version control systems but popular today are distributed reversion control systems like Git and Mecurial, and server-client revision control systems like Apache Subversion (or SVN).
There are many online services that offer free accounts that allow you to back up your data to cloud based revision control services. Here are two that I know of but some web searching will discover many more.
- free unlimited private repositories for up to 5 users
- options to use Git and/or Mercurial
- free desktop clients for Git and Mercurial for Mac and Windows
- unlimited public repositories for unlimited number of users
- private repositories cost (see Plans & pricing)
- use Git or SVN
- free desktop clients for Mac and Windows