I was wondering whether, in case of a PC crash, the backups made by Zotero automatically would also enable me to recover my tags, the organisation of which has taken me considerable effort. Thanks!
Both they synced database and the backup of the local database contain tags and collections, yes. Note that you should not be relying exclusively on sync for back-up. You should have an additional local back up of your Zotero database: https://www.zotero.org/support/zotero_data#backing_up_your_zotero_library
Thanks ! I am indeed using local backups for my PDFs (namely, backing up the Storage folder), and relying on Sync for the tags, as I did not find a way to back up tags/collections manually. Perhaps Time Machine could do that on a Mac - I am using Windows...
https://www.zotero.org/support/zotero_data#backing_up_your_zotero_library