The 3Com EtherLink 10100 PCI NIC (3C905-TX) is a network interface card (NIC) from 3Com that provides 10/100 Mbps Ethernet connectivity. It's an older model, often used in desktop PCs or workstations to connect to local area networks (LANs). The driver allows Windows to communicate with the hardware and use its networking features, including setting up IP addresses and managing data traffic.