Version control is the comfortable insurance that means you can sleep soundly at night.
A version control system (VCS) keeps track of the differences in versions of content. Properly implemented, it is nearly disaster proof.
When a document is saved in to a VCS, the difference between the current saved copy and the one just before it is stored. The same occurred at all previous saves. This makes it possible to restore a document to any point in its save history. It is also possible to return to a previous save point and start a new pathway of saves from there. In code this is called branching, with the original code in the central trunk.
When you work with a web-based tool to write, edit, and display a document, you are using version control. All content management systems and wikis use a form of version control to capture and display the differences between edits.
Version control provides noisy reporting. Anyone who is interested or able may watch the stream of changes, or derive reports from them. Watching and commenting on version saves as they occur is a hallmark of the open source methodology.