I always start at https://en.wikipedia.org/wiki/CAN_bus.

There we learn :

1. Invented by Bosch with automotive in mind
2. Therefore thought to be robust and manage priorities (when multiple device try to talk at the same time, there is a system that make sure that only the most priority device can talk while the other shuts…) we will have to discover how that works ;)
3. Based on two wires (CAN-L and CAN-H)