Section snapshots are a way of preserving multiple versions of each section over time, as a way to go back and read older revisions and even restore them if a radical edit went wrong and you're unhappy with the result.
You can save snapshots of your work manually at any time. When you restore any of these snapshots, an automatic snapshot will be saved prior to the restoration, to prevent accidents.
The ability to save snapshots per section spares you having to go through large older revisions containing the whole book just to see what you were writing in a particular chapter a month ago.
Let's see how snapshots work, using this very section as an example.
NOTE: snapshots are not available offline, as they are not stored locally.