Snapshots is version history for a scene or a chapter. Each capture stores the text as it stood, together with its timestamp, word count and any label applied to it, which is what makes an earlier draft comparable and restorable.
How a capture is taken
Three ways. Automatically, as you write, without any action on your part. On your instruction, as a named checkpoint. And by a restore, which captures the text it is about to overwrite before overwriting it. There is no button that must be remembered before attempting a rewrite.
Reading the history
Each entry shows its word count and the change from the entry before it, so a substantial rewrite is distinguishable from a light edit without opening either version. A label, where one was applied, is shown alongside.
Restoring
Restoring returns a scene or chapter to a stored version. It affects that document only; the rest of the manuscript is unchanged. Because the restore captures the text it replaces, a restore may itself be undone by restoring the capture it created, which appears at the top of the history.
Retention limits
Not every entry can be restored. Per scene and per chapter, the 20 most recent captures retain their text, as do the 50 most recent captures taken on your instruction or created by a restore. Older entries retain their timestamp, word count and position in the history but not the text, and can therefore be read as a record but not opened as a version.
The operational consequence: if a draft may be wanted months from now, take a checkpoint yourself and name it. A checkpoint is retained far longer than an automatic capture, and a name is what makes it findable in a long history. Captures are deleted with the scene or chapter they belong to, and with the book or the account, as set out in the data deletion notice.