CAN stands for Controller Area Network, it is used to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer which allows for control and data acquisition. These devices are also called Electronic Control Units (ECU) and they enable communication between all parts of a vehicle.
Today, you can find up to 70 ECUs in a modern car. CAN is a serial communication bus designed for industrial and automotive applications.
CAN without CAN
CAN BUS Wiring