This document provides an overview of the Controller Area Network (CAN) protocol. It was initially created by Bosch in the 1980s for automotive applications to enable robust serial communication and make vehicles more reliable, safe and fuel-efficient. CAN has since gained widespread use in industrial automation and other fields. The document explains that CAN uses a message-based communication protocol and carrier sense multiple access with collision detection. It also describes CAN message frames, arbitration, and other key aspects of the CAN protocol.