Fiber optics (optical fibers) are long, thin strands of very pure glass about the diameter of a human hair. They are arranged in bundles called optical cables and used to transmit light signals over long distances.

Why are fiber-optic systems revolutionizing telecommunications? Compared to conventional metal wire (copper wire), optical fibers are:

>	Less expensive	Several miles of optical cable can be made cheaper than equivalent lengths of copper wire. This saves your provider (cable TV, Internet) and you money.
>	Thinner	Optical fibers can be drawn to smaller diameters than copper wire.
>	Higher carrying capacity	Because optical fibers are thinner than copper wires, more fibers can be bundled into a given-diameter cable than copper wires. This allows more phone lines to go over the same cable or more channels to come through the cable into your cable TV box.
>	Less signal degradation	The loss of signal in optical fiber is less than in copper wire.
>	Light signals	Unlike electrical signals in copper wires, light signals from one fiber do not interfere with those of other fibers in the same cable. This means clearer phone conversations or TV reception.
>	Low power	Because signals in optical fibers degrade less, lower-power transmitters can be used instead of the high-voltage electrical transmitters needed for copper wires. Again, this saves your provider and you money.
>	Digital signals	Optical fibers are ideally suited for carrying digital information, which is especially useful in computer networks.
>	Non-flammable	Because no electricity is passed through optical fibers, there is no fire hazard.
>	Lightweight	An optical cable weighs less than a comparable copper wire cable. Fiber-optic cables take up less space in the ground.
>	Flexible	Because fiber optics are so flexible and can transmit and receive light, they are used in many flexible digital cameras for the following purposes:   Medical imaging in bronchoscopes, endoscopes, laparoscopes   Mechanical imaging inspecting mechanical welds in pipes and engines (in airplanes, rockets, space shuttles, cars)   Plumbing to inspect sewer lines

Because of these advantages, you see fiber optics in many industries, most notably telecommunications and computer networks. For example, if you telephone Europe from the United States (or vice versa) and the signal is bounced off a communications satellite, you often hear an echo on the line. But with transatlantic fiber-optic cables, you have a direct connection with no echoes.