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The Internet is a (36) network of computers (37) all over the world that communicate with each other. The Internet is an international collection of computer networks that all understand a (38) system of addresses and commands, connected together through backbone systems. It was started in 1969, when the U.S. Department of Defense (39) a nationwide network to connect a handful of universities and contractors. The (40) idea was to increase computing (41) that could be shared by users in many locations and to find out what it would take for computer networks to (42) a nuclear war or other disaster by providing multiple paths between users. People on the ARPNET (as this nationwide network was originally called) quickly discovered that they could (43) messages and conduct electronic "conferences" with distant colleagues for purposes that had nothing to do with the military industrial complex. (44) (45) The first international connections, to Norway and England, were added in 1973. Today thousands of networks and millions of computers are connected to the Internet. It is growing so quickly that nobody can say exactly how many users "On the Net". (46) .