The device used to connect a computer to a local area network (LAN) is called a network interface card (NIC) or card. NICs, embedded in most computers and laptops or used as external devices, enable data transfer between the computer and the network. They facilitate communication over various transmission media, such as Ethernet cables or Wi-Fi. A properly functioning NIC is crucial for connecting computers to share resources, access the internet, and communicate with other devices within a LAN.