Network cabling comes in three flavors: twisted pair, coaxial, and fiber optic. Twisted pair
Twisted pair cabling is a form of wiring in which two wires (the forward and return conductors of a single circuit) are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources. This type of cable is used for home and corporate Ethernet networks. Twisted pair cables consist of two insulated copper wires. There are three types of twisted pair cables: Shielded, Unshielded and Foil Fiber Optic cable
An optical fiber cable consists of a center glass core surrounded by several layers of protective material. The outer insulating jacket is made of Teflon or PVC to prevent interference. It is expensive but has higher bandwidth and can transmit data over longer distances. Coaxial cable
Coaxial lines confine the electromagnetic wave to area inside the cable, between the center conductor and the shield. The transmission of energy in the line occurs totally through the dielectric inside the cable between the conductors. Coaxial lines can therefore be bent and twisted (subject to limits) without negative effects, and they can be strapped to conductive supports without inducing unwanted currents in them and though.
The most common use for coaxial cables is for television and other signals with bandwidth of multiple megahertz. Although in most homes coaxial cables have been installed for transmission of TV signals, new technologies (such as the ITU-T G.hn standard) open the possibility of using home coaxial cable for high-speed home networking applications (Ethernet over coax).
See the following page for more details: http://fcit.usf.edu/network/chap4/chap4.htm
Reference used for this question:
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 101. and Wikipedia at http://en.wikipedia.org/wiki/Networking_cables