Communications technology combined with computers is the foundation of the technology revolution we are living through today. The oldest form of long distance communication was the hand carrying of clay tablets, scrolls, journals and books by couriers with and without mounts. The first mechanized long distance communication system was put into production by the Scandinavians and the French around the time of Napoleon: a series of manned towers, spaced a few kilometers apart which relayed coded messages by arranging signal flags to signify letters and words. Today we would describe the transmission speed as 60 bytes per hour. The telegraph and telephone, of course, speeded things up by factors of hundreds; a good railroad telegrapher could click out 100 words a minute.
The newest forms of communication are phone and data delivery by means of multiple overlapping radio transmitters and receivers arranged geographically into small areas called cells. PCS, short for personal communications system, is the same thing under a different name.
Television, or more broadly, video can be used not only for one-way communication to a passive recipient but can also be used for active two-way communication.
