A group of computers that are interconnected in order to share information or documents is called a computer network. The computers, which are referred to as nodes, are connected via cabling, most commonly the Ethernet cable, or wirelessly through radio waves. Depending on how the computers are interconnected the topology can be star( a central node extends a cable to each computer on the network), bus (a single cable connects all computers) or ring (computers are connected via a single cable, but the end nodes also are connected to each other).