The scariest moment in writing is the big rewrite — and the deleted paragraph you want back three weeks later. Folio Writer's answer is layered: snapshots you take, snapshots it takes for you, and a rule that nothing conflicting is ever overwritten.
Before gutting a chapter, snapshot it (File ▸ Snapshots). A snapshot freezes the document's text with a label and date; the changes view diffs any snapshot against the present — colored, side by side — and restore brings it back wholesale (itself undoable). Snapshot freely: they're text, they cost nothing.
Two automatic baselines: arming Track Changes snapshots the pristine text ("Track Changes started"), so review is always against a fixed original. And every compile can keep a snapshot of the exact text that produced it — "the version we submitted in March" becomes a fact you can diff, not a memory.
History is kept per document, not per project — restoring one section's earlier state never touches the rest of the manuscript.
When two devices edit the same passage before syncing, Folio Writer merges what it safely can and preserves a conflict copy of anything it can't — the rule everywhere is that data survives and a human decides. (More in the sync & iOS guide.) Snapshots and version history are part of the one-time Pro unlock; conflict-safe recovery is free for everyone, always.