Optical fibers transmit light signals over long distances through the process of total internal reflection. They consist of a core and cladding - the core guides light down its length, while the cladding reflects light back into the core. This allows signals to travel for miles with little degradation. Fiber optic systems have transmitters that produce light signals, fibers that conduct them, and receivers that decode the signals. They provide more efficient, higher capacity data transmission than copper wires.