An ethernet adapter is a small card that plugs into the motherboard of a computer. It can connect the computer to a local network or the Internet.
Most new computers have network or Internet connection capabilities built in and don't need ethernet adapters. However, older desktop computers can be fitted with ethernet adapters in order to become network-ready. Servers and large networks may also use ethernet adapters. An ethernet adapter is also known as a network interface card. To install an ethernet adapter into a desktop, users can usually just plug the card into its corresponding slot in the computer tower.