The Ethernet controller, also known as the Ethernet adapter, is what we commonly refer to as the “network card”. Its installation method is to insert it into the PCI expansion slot on the motherboard of the machine. It is usually white, and then by installing the driver disc included in the purchased network card, it can be installed. The Ethernet controller uses a specific physical layer and data link layer standard, such as Ethernet or Token Ring, to implement the circuit system required for communication. This provides a foundation for a complete network protocol stack, enabling small computer groups in the same local area network and wide area networks connected through routing protocols, such as IP, to communicate. An Ethernet controller usually comes with a twisted pair cable, optical fiber, BNC, AUI, and HomePNA interface. Among them, the latter three are less common nowadays, and optical fiber is mostly used for servers.