The 3Com EtherLink III Bus-Master PCI Ethernet Adapter is a network interface card (NIC) designed to provide Ethernet connectivity to computers via a PCI (Peripheral Component Interconnect) slot. The Windows driver for this card allows your computer's operating system to communicate with the network card and use it to connect to local area networks (LANs) or the internet. The Bus-Master term indicates that the adapter is capable of taking control of data transfer between the network and system memory, resulting in improved performance.