Ethernet can be used for cabled communication between an Arduino and a computer, server, or website. For question concerning the Arduino Ethernet board, use the tag "arduino-ethernet" instead.
Ethernet can be used for communication between an Arduino and a computer. It is defined as a system for connecting a number of computer systems to form a local area network, with protocols to control the passing of information and to avoid simultaneous transmission by two or more systems
Additionally, there is an Arduino Ethernet Shield. Use this tag for the shield.