NIC stands for Network Interface Card. They are colloquially referred to as Ethernet cards. These plug into a computer and allow it to send and receive information to local- and wide-area networks. Most modern computers have NICs built into them. NICs tend to be far more reliable since they have a physical connection to the router or server that controls their access, versus a wireless connection that has to contend with losing signal strength due to intervening objects (walls, furniture, etc.) and weather conditions.