An Ethernet cable is a cable specified by the Ethernet standards for networking. Ethernet applies to standards managed by the Institute of Electrical and Electronics Engineers. The standards are produced with the code 802.3 and specify the physical properties of networks including the cable type.
The networking part of a computer is called a network adaptor. No computer can connect to a network without one of these, as it is the network adaptor that provides the physical address of the computer on the network and converts computer data into a signal suitable for transmission over cable. The cable's role is to connect network adaptors together. This forms the network.
One computer linked to one other computer by a cable does not make a network. The computer needs to be able to contact more than one other computer. For this reason, the cable needs to branch out to connect to many other end points. This task is performed by a splitter. In networking terms, the splitter is called a hub or a switching hub, or a switch. Each strand of cable connects a computer's network adaptor to a splitter which directs incoming data onto another cable leading out to another computer. By this arrangement, Ethernet cable links all the essential elements of a network.
The important element of an Ethernet cable is the conductor. This is usually a copper wire that carries an electrical charge. The electric charge is applied in a way that can be interpreted into meaningful data. The voltage pulses over the cable and any device connected to that cable receives that charge. The cable is not able to understand the data travelling over it, it merely carries it. It is up to the connected devices to interpret a particular pattern of electronic pulse into specific information.
The Ethernet cable would not be a useful medium for a network if it were vulnerable to interference. The main task of carrying an electronic charge has to be carried out without letting external magnetic influences alter the pattern of electric pluses carried on the cable. Most Ethernet applications use a form of cable called unshielded twisted pair, or UTP. UTP contains pairs of wires, each pair representing the positive and negative path of a complete circuit. Twisting these pairs together protects from magnetic interference. Earlier forms of cable used for Ethernet networks protected the wired with a metal tube, called a shield. UTP does not need this protection and so is cheaper to produce and more widely implemented.