A type of
cable that transmits
data as
light through strands of
glass instead of electricity through
copper. Fiber-optic cable is a
wonderful thing; it can transmit almost
insane amounts of data per
second, and it is completely
impervious to
surges,
magnetic fields,
lightning, and all the other EM nasties that can affect
copper cable. Unfortunately it's not impervious to
hicks bulldozing big
holes in the ground for their
swimming pools, but I doubt anything ever will be.
A few layer-1 protocols that are used over fiber include
OC-3, OC-12, OC-48, 100base-FL, 100base-FX, and many,
many more.