What's the flow of data for using VR in Unity?

Hello all,

This week I started my first project in Unity that uses VR for a university project. I was given a quick guide on how to set everything up, and it said to download the SteamVR plugin (the program was already installed), the XR plugin and the HTC plugin, as we're using HTC Vive.

It seems to be working, as I can launch the scene in VR and the controllers are tracked. What I don't understand is how the data flows from the scene to the VR and viceversa. I have looked at some tutorials on interactions and in the code I call the SteamVR object, so I guess that's the bridge between the headset and Unity but if someone could give a more detailed explanation I'd really appreciate it