This is the future home of some massively interlinked wiki pages describing how the Volity system works. For the time being, you can read a somewhat outdated but still largely correct description of the system in
[this essay].
There is also a game developer's overview which describes just the stuff you need to know to create a game.
Volity concept index
The Volity network entirely comprises only a few different types of entities, all of which are simply connections to the underlying Jabber network.
Other key concepts