High-speed communication works the same way whether we use pulses of electrical current, radio waves or light. There is an internationally agreed upon code for what any short sequence of pulses mean. How fast and far you can communicate depends upon how short you can make the pulses and how far the pulses can travel and still be detected. If you send pulses of electrical current in wires, the two effects fight one another and the faster the pulses, the shorter they will go before they die away.

If you use radio waves, there are two problems. Anyone can detect them, and you can't pulse faster than the frequency of the waves. Infrared light of wavelength 1.6 microns oscillates at nearly two hundred thousand billion times per second, so you can pulse it way over a billion times per second with no problem.

An optical fiber is a thread of very pure glass which can carry this light for hundreds of miles and you can put over a hundred different colors of light in the same glass fiber all carrying different information. This much information capacity is critical to carry the data traffic of the internet, television, phone conversations and hundreds of other uses.