Communication technology

People have always found ways to send messages far. Fires on hilltops passed a simple warning; riders on fresh horses carried letters from post house to post house; the telegraph sent letters as short and long pulses of electricity along a wire; the telephone carried the voice itself; radio and television reached millions of homes without wires; the internet joined computers across the world, and the smartphone put it all in a pocket. Each new technology solved a problem of the one before it.