Physical Layer __ Computer network

The physical layer is the lowest layer of the network architecture and is the only one layer that transmits data directly. But the physical layer does not refer to the specific physical device or specific transmission medium that connects the computer, it mainly considers how to transfer bits of data on the transmission medium connected to the open system.

Another function of the physical layer is to shield the differences between physical devices and transmission media as much as possible, and to provide a unified data transmission service for the link layer.