How the Internet Changed History

How the Internet Changed History — page 7
How the Internet Sends Messages The purpose of the Internet is to send messages billions and billions of them Some are simple text messages Others are encyclopedic amounts of information on every topic imaginable Some are photographs videos or movies Others are maps blueprints financial information or military codes All of this information must be broken down into digital code codes composed of ones and zeroes This digital information travels from the building where it originates through a series of tubes buried along roads and railroad tracks across the bottom of the ocean and on to other buildings around the world Its travel is anything but random Each tiny packet of information is labeled with its own unique address and its destination's unique address The information is sent from a single router today's equivalent of an IMP to nearby routers which then transfer it to routers near them In this way the unique packet of information reaches around the world Billions of information packets zip past continually each one uniquely labeled to be decoded at its destination Physically the tubes contain fiber optic cables bundles of glass strands each as thin as a human hair These cables carry digital information in the form of light across very long distances Computers at the beginning and end of the data transmission have components called transducers which transform the data from digital data to light and back Fiber optic cables transmit information for the Internet telephone systems and cable television 12