Twisted Pair wiring (Cat 3 and Cat 5) are popular methods of transferring data. They are especially prevalent in the LAN environment. The twists allow the signal to travel further than it could on a regular copper wire. The more twists per centimeter, the further the signal can travel. This is why Cat 5 wire (with more twists) is preferred over Cat 3 wire. Twisted pair wires consist of two strands of copper twisted together; the wires are unshielded, which is why Twisted Pair wire is also called Unshielded Twisted Pair (UTP).
Fiber optics is one of the advances that has propelled communication technology into the future at high speeds. Communication over fiber optics requires a source (of light), a line (transmission medium = fiber), and a destination (to detect the light). The light stays within the fiber line because of the angle at which the light hits the surface of the fiber line. Instead of passing through the fiber's surface (like a window), the light bounces off of it (like a mirror). The light propagates down the fiber line because it continually reflects off the surface from the inside; the light never escapes the fiber line until the receiver detects it. Like copper, fiber optics suffers problems when transmitting over a distance. Attenuation (a weakening of the power of a signal) occurs, as well as dispersion (the spreading out of light waves over a distance). The discovery of solitons has helped wipe out the problem of dispersion, though. A fiber cable is heavily insulated like coax, but it has several differences. The core of the cable is a glass strand, which is surrounded by a thick glass covering, which is then covered by plastic. When compared to copper for its overall purposes, fiber wins because it is lighter, higher bandwidth, easier to install, harder to tap, and the signal stays stronger longer than in copper. The only drawback to fiber at this point in time is the lack of familiarity among the engineering community with the fiber technology compared to the copper.