How to Connect Strapi to PostgreSQL

Quick question: In this article, we break down the structure in the database.js file, but we pretty much skip over what the bookshelf value of the connection actually means. We see:

“In this default connection, we set the connector to the bookshelf.”

Could you please elaborate on the connection object, but in particular, what setting it to “bookshelf” actually does. Is that an arbitrary name? Who (or what) uses that name? Can we change it at will?

Is it a database name, or a schema name, or a table name, or a row name, or… what?

Maybe I’ve got a “forest and tree” understanding problem – Is it some basic fundamental entity that’s crucial to Strapi, and so implicit (as in “it’s the default, and you always configure it that way”) that I haven’t really even thought about it?

Maybe it’s specified in an ORM (or data model) somewhere? Kinda like Django-style?