Enter the Dragon
You stumble through a maze of mirrors, placed methodically so that the camera filming you doesn't film itself... you have hot pink fluids smeared over your arms and torso as an obscure, esoteric reference to human blood... there is a chinese actor chasing you with an over-sized rabbit's foot with marshmallow roasters attached to the fingers as an obscure esoteric reference to a bear-claw-esque weapon (which will henceforth be reverenced in the form of a mouth-watering innamon/frosting medley pastry).

Is this the freakiest haunted carnival fun house ever? Is it a story Spielberg, Coppola, Lucas, and the like tell over a campfire to try to scare each other sleepless? None of the above! This horror (multiplied by several millions) is what a poor innocent signal particle experiences every time he/she is sent through the most horrible rollercoaster of death: the fiber optic cable.

Enter the Nightmare
Fiber optic cable is virtually a tube lined on the inside with a flexible mirror that bounces the poor innocent signal particle around until it gets to the other side. Imagine trying to shine a light down a bending tunnel. If the tunnel is lined on the inside by mirrors, the light will bounce around until it finally arrives at the end. More specifically:
each optical fiber has three layers:
1.Core: A thin glass center of the fiber where the signal/light particle travels
1.5.Scary Chinese actor with over-sized rabbit's foot
2.Cladding: Optical Material that surrounds the core and reflects the light back into the core.
3.Buffer Coating: Plastic coating that protects the fiber from damage and moisture.

Thousands of hundreds of tens of a couple of these fibers are arranged in bundles in optical cables in an outer covering called a "jacket".

Single Mode Lee vs. Multi-mode bear-claw man
Optic fibers come as Single-mode fibers and Multi-mode fibers.

Single Mode fibers have small cores (about 9 microns in diameter) and transmit infrared laser light.

Multi-mode fibers have larger cores (about 62.5 microns in diameter) and transmit infrared light from LEDs (light emitting diodes).

Who Cares How it Works, Get Back to the Scary Chinese Actor with the Bear-Claw
Lets talk advantages to Fiber over Copper:
Thinner- Optical fibers can be drawn to smaller diameters than copper wire.
Less Signal Degradation- fiber optic cable not only can be used in networks, but to extend USB, Firewire, DVI, and other types of signals that degrade over short distances. Gefen, for instance, carries a great DVI extender that will carry your DVI signal up to 1640 feet, for when you want to do a powerpoint at a Vegas trade show at the Belagio without leaving the dollar black jack machine at "Jim's Food and Fuel Safari" somewhere far away from the strip.

No Interference- Interference will someday be extinct from the english language except when used soley to refer to the famous playground Deus ex Machina that saved you from total dodgeball humiliation. In other words, with the advent of fiber optics, information will be sent through light signals and not electrical signals (used with copper wires), eliminating that nasty bully called interference.

Less Power- Because signals in fiber optics degrade less, less power is needed to make degradation corrections.
No Fire Hazard- Since light (not electricity) being passed through these cables, there is no fire hazard.
Flexible- Fiber optic cable is smaller, more flexible, and therefore more agile than copper. It is especially useful in medical imaging, mechanical imaging, plumbing, etc.