Document

Document is SQLite database which contains all notes, metadata, even some of the configuration.

It's stored in single file, by default in trilium-data/document.db

If you want to backup your Trilium data, just backup this single file - it contains everything you need.

Trilium has been originally created as a web interface to the Notecase Pro, as such it used same database format as Notecase Pro. Database format evolved and today it's not compatible with Notecase Pro even though there are still some similarities in its schema.