Zotonic’s data model can be seen as a pragmatic implementation of the Semantic Web: a mixture between a traditional database and a triple store.
Resources, which are often called pages in the admin, are the main data unit: they have properties like title, summary, body text; and importantly, they belong to a certain category.
Edges are nothing more than connections between two resources. Each edge is labeled, with a so-called predicate.
This manual describes the data model and its related database table in depth.