ARPANET The Advanced Research Projects Agency Network ( ARPANET ) was one of the world ' s first operational packet switching networks , the first network to implement TCP / IP , and the progenitor of what was to become the global Internet . The network was initially funded by the Advanced Research Projects Agency ( ARPA , later DARPA ) within the U . S . Department of Defense for use by its projects at universities and research laboratories in the US . The packet switching of the ARPANET , together with TCP / IP , would form the backbone of how the Internet works . The packet switching was based on concepts and designs by American engineer Paul Baran , British scientist Donald Davies and Lawrence Roberts of the Lincoln Laboratory . The TCP / IP communication protocols were developed for ARPANET by computer scientists Robert Kahn and Vinton Cerf . History . Packet switching , today the dominant basis for data communications worldwide , was a new concept at the time of the conception of the ARPANET . Prior to the advent of packet switching , both voice and data communications had been based on the idea of circuit switching , as in the traditional telephone circuit , wherein each telephone call is allocated a dedicated , end to end , electronic connection between the two communicating stations . Such stations might be telephones or computers . The ( temporarily ) dedicated line is typically composed of many intermediary lines which are assembled into a chain that stretches all the way from the originating station to the destination station . With packet switching , a data system could use a single communications link to communicate with more than one machine by collecting data into datagram s and transmitting these as packets onto the attached network link , as soon as the link becomes idle . Thus , not only can the link be shared , much as a single post box can be used to post letters to different destinations , but each packet can be routed independently of other packets . The earliest ideas for a computer network intended to allow general communications among computer users were formulated by computer scientist J . C . R . Licklider of Bolt , Beranek and Newman ( BBN ) , in April 1963 , in memoranda discussing his concept for an " Intergalactic Computer Network " . Those ideas contained almost everything that composes the contemporary Internet . In October 1963 , Licklider was appointed head of the Behavioral Sciences and Command and Control programs at the Defense Department ' s Advanced Research Projects Agency — ARPA ( the initial ARPANET acronym ) . He then convinced Ivan Sutherland and Bob Taylor that this computer network concept was very important and merited development , although Licklider left ARPA before any contracts were let that worked on this concept . Ivan Sutherland and Bob Taylor continued their interest in creating such a computer communications network , in part , to allow ARPA - sponsored researchers at various corporate and academic locales to put to use the computers ARPA was providing them , and , in part , to make new software and other computer science results quickly and widely available . In his office , Taylor had three computer terminals , each connected to separate computers , which ARPA was funding : the first , for the System Development Corporation ( SDC ) Q - 32 , in Santa Monica ; the second , for Project Genie , at the University of California , Berkeley ; and the third , for Multics , at MIT . Taylor recalls the circumstance : " For each of these three terminals , I had three different sets of user commands . So , if I was talking online with someone at S . D . C . , and I wanted to talk to someone I knew at Berkeley , or M . I . T . , about this , I had to get up from the S . D . C . terminal , go over and log into the other terminal and get in touch with them . I said , " Oh Man ! " , it ' s obvious what to do : If you have these three terminals , there ought to be one terminal that goes anywhere you want to go . That idea is the ARPANET " . Somewhat contemporaneously , several other people had ( mostly independently ) worked out the aspects of " packet switching " , with the first public demonstration presented by the National Physical Laboratory ( NPL ) , on 5 August 1968 , in the United Kingdom . Creation . By mid - 1968 , Taylor had prepared a complete plan for a computer network , and , after ARPA ' s approval , a Request for Quotation ( RFQ ) was sent to 140 potential bidders . Most computer science companies regarded the ARPA – Taylor proposal as outlandish , and only twelve submitted bids to build the network ; of the twelve , ARPA regarded only four as top - rank contractors . At year ' s end , ARPA considered only two contractors , and awarded the contract to build the network to BBN Technologies on 7 April 1969 . The initial , seven - man BBN team were much aided by the technical specificity of their response to the ARPA RFQ – and thus quickly produced the first working computers . This team was led by Frank Heart . The BBN - proposed network closely followed Taylor ' s ARPA plan : a network composed of small computers called Interface Message Processor s ( IMPs : today called routers ) , that functioned as gateways interconnecting local resources . At each site , the IMPs performed store - and - forward packet switching functions , and were interconnected with modems that were connected to leased line s , initially running at . The host computers were connected to the IMPs via custom serial communication interfaces . The system , including the hardware and the packet switching software , was designed and installed in nine months . The first - generation IMPs were initially built by BBN Technologies using a rugged computer version of the Honeywell DDP - 516 computer configured with of expandable core memory , and a 16 - channel Direct Multiplex Control ( DMC ) direct memory access unit . The DMC established custom interfaces with each of the host computers and modems . In addition to the front - panel lamps , the DDP - 516 computer also features a special set of 24 indicator - lamps showing the status of the IMP communication channels . Each IMP could support up to four local hosts , and could communicate with up to six remote IMPs via leased lines . The network connected one computer in Utah with three in California . Later , the Department Of Defense allowed the universities to join the network for sharing hardware and software resources . Misconceptions of design goals . Common ARPANET lore posits that the computer network was designed to survive a nuclear attack . In " A Brief History of the Internet " , the Internet Society describes the coalescing of the technical ideas that produced the ARPANET : Although the ARPANET was designed to survive subordinate - network losses , the principal reason was that the switching nodes and network links were unreliable , even without any nuclear attacks . About the resource scarcity that spurred the creation of the ARPANET , Charles Herzfeld , ARPA Director ( 1965 – 1967 ) , said : Packet switching pioneer Paul Baran affirms this , explaining : " Bob Taylor had a couple of computer terminals speaking to different machines , and his idea was to have some way of having a terminal speak to any of them and have a network . That ' s really the origin of the ARPANET . The method used to connect things together was an open issue for a time . " ARPANET deployed . The initial ARPANET consisted of four IMPs : The first message on the ARPANET was sent by UCLA student programmer Charley Kline , at 10 : 30 pm on 29 October 1969 , from Boelter Hall 3420 . Kline transmitted from the university ' s SDS Sigma 7 Host computer to the Stanford Research Institute ' s SDS 940 Host computer . The message text was the word " login " ; the " l " and the " o " letters were transmitted , but the system then crashed . Hence , the literal first message over the ARPANET was " lo " . About an hour later , having recovered from the crash , the SDS Sigma 7 computer effected a full " login " . The first permanent ARPANET link was established on 21 November 1969 , between the IMP at UCLA and the IMP at the Stanford Research Institute . By 5 December 1969 , the entire four - node network was established . Growth and evolution . In March 1970 , the ARPANET reached the East Coast of the United States , when an IMP at BBN in Cambridge , Massachusetts was connected to the network . Thereafter , the ARPANET grew : 9 IMPs by June 1970 and 13 IMPs by December 1970 , then 18 by September 1971 ( when the network included 23 university and government hosts ) ; 29 IMPs by August 1972 , and 40 by September 1973 . By June 1974 , there were 46 IMPs , and in July 1975 , the network numbered 57 IMPs . By 1981 , the number was 213 host computers , with another host connecting approximately every twenty days . In 1973 a transatlantic satellite link connected the Norwegian Seismic Array ( NORSAR ) to the ARPANET , making Norway the first country outside the US to be connected to the network . At about the same time a terrestrial circuit added a London IMP . In 1975 , the ARPANET was declared " operational " . The Defense Communications Agency took control since ARPA was intended to fund advanced research . In 1983 , the ARPANET was split with U . S . military sites on their own Military Network ( MILNET ) for unclassified defense department communications . The combination was called the Defense Data Network ( DDN ) . Separating the civil and military networks reduced the 113 - node ARPANET by 68 nodes . Gateways relayed electronic mail between the two networks . MILNET later became the NIPRNet . Rules and etiquette . Because of its government ties , certain forms of traffic were discouraged or prohibited . A 1982 handbook on computing at MIT ' s AI Lab stated regarding network etiquette : Technology . Support for inter - IMP circuits of up to 230 . 4 kbit / s was added in 1970 , although considerations of cost and IMP processing power meant this capability was not actively used . 1971 saw the start of the use of the non - ruggedized ( and therefore significantly lighter ) Honeywell 316 as an IMP . It could also be configured as a Terminal Interface Processor ( TIP ) , which provided terminal server support for up to 63 ASCII serial terminals through a multi - line controller in place of one of the hosts . The 316 featured a greater degree of integration than the 516 , which made it less expensive and easier to maintain . The 316 was configured with 40 kB of core memory for a TIP . The size of core memory was later increased , to 32 kB for the IMPs , and 56 kB for TIPs , in 1973 . In 1975 , BBN introduced IMP software running on the Pluribus multi - processor . These appeared in a small number of sites . In 1981 , BBN introduced IMP software running on its own C / 30 processor product . In 1983 , TCP / IP protocols replaced NCP as the ARPANET ' s principal protocol , and the ARPANET then became one subnet of the early Internet . Shutdown and legacy . The original IMPs and TIPs were phased out as the ARPANET was shut down after the introduction of the NSFNet , but some IMPs remained in service as late as 1989 . The " ARPANET Completion Report " , jointly published by BBN and ARPA , concludes that : In the wake of ARPANET being formally decommissioned on 28 February 1990 , Vinton Cerf wrote the following lamentation , entitled " Requiem of the ARPANET " : It was the first , and being first , was best , Now pause with me a moment , shed some tears . For auld lang syne , for love , for years and years - Vinton Cerf Senator Albert Gore , Jr . began to craft the High Performance Computing and Communication Act of 1991 ( commonly referred to as " The Gore Bill " ) after hearing the 1988 report toward a National Research Network submitted to Congress by a group chaired by Leonard Kleinrock , professor of computer science at UCLA . The bill was passed on 9 December 1991 and led to the National Information Infrastructure ( NII ) which Al Gore called the " information superhighway " . ARPANET was the subject of two IEEE Milestones , both dedicated in 2009 . Software and protocols . The starting point for host - to - host communication on the ARPANET in 1969 was the 1822 protocol , which defined the transmission of messages to an IMP . The message format was designed to work unambiguously with a broad range of computer architectures . An 1822 message essentially consisted of a message type , a numeric host address , and a data field . To send a data message to another host , the transmitting host formatted a data message containing the destination host ' s address and the data message being sent , and then transmitted the message through the 1822 hardware interface . The IMP then delivered the message to its destination address , either by delivering it to a locally connected host , or by delivering it to another IMP . When the message was ultimately delivered to the destination host , the receiving IMP would transmit a " Ready for Next Message " ( RFNM ) acknowledgement to the sending , host IMP . Unlike modern Internet datagrams , the ARPANET was designed to reliably transmit 1822 messages , and to inform the host computer when it loses a message ; the contemporary IP is unreliable , whereas the TCP is reliable . Nonetheless , the 1822 protocol proved inadequate for handling multiple connections among different applications residing in a host computer . This problem was addressed with the Network Control Program ( NCP ) , which provided a standard method to establish reliable , flow - controlled , bidirectional communications links among different processes in different host computers . The NCP interface allowed application software to connect across the ARPANET by implementing higher - level communication protocols , an early example of the " protocol layering " concept incorporated to the OSI model . In 1983 , TCP / IP protocols replaced NCP as the ARPANET ' s principal protocol , and the ARPANET then became one component of the early Internet . Network applications . NCP provided a standard set of network services that could be shared by several applications running on a single host computer . This led to the evolution of " application protocols " that operated , more or less , independently of the underlying network service . When the ARPANET migrated to the Internet protocols in 1983 , the major application protocols migrated with it . ARPANET in film and other media . Post - ARPANET . In " Let the Great World Spin : A Novel " , published in 2009 but set in 1974 and written by Colum McCann , a character named The Kid and others use ARPANET from a Palo Alto computer to dial phone booths in New York City to hear descriptions of Philippe Petit ' s tight rope walk between the World Trade Center Towers .