A backup is a single archive of your whole library: notes, attachments, structure and all. Backups work across platforms, so a backup made on a Mac restores on Windows or Linux.
Automatic backups
Grape backs up on its own once a day and keeps the last thirty days of these. You do not have to think about them, they are just there when something goes wrong.
Manual backups
Open Settings, go to the Backups tab and choose Back Up Now. Manual backups are kept until you delete them, which makes them the right tool before anything risky: a big reorganization, an import, trying a restore.
Backups the app takes for you
Two more kinds appear in the list, each labeled: a backup taken before the AI makes bigger changes to your library, and one taken automatically before any restore. Both exist so that no action in Grape is a one way door.
Where they live
Backups are local files on the device that made them. They are not the same thing as sync, which mirrors your library between devices but does not keep historical archives. For a copy that survives the device itself, move a manual backup somewhere of your own from time to time.