posted by timothy .
What is an optical fibre? Briefly describe how they are used.
A long skinny tube of glass that reflects light that hits the walls from inside right back down the tube, keeping the light pretty much inside and as much as possible undiminished. Light is short wavelength (high frequency) and therefore high bandwidth (carries a lot of information per second) and therefore a light signal is very useful for high bandwidth transmission of signals.
Ah, here is a decent description of how fiber optic cable works and is built: