The internet

Inspiration
Christopher Strachey, who became Oxford University's first Professor of Computation, filed a patent application for time-sharing in February 1959.^[31][32] In June that year, he gave a paper "Time Sharing in Large Fast Computers" at the UNESCO Information Processing Conference in Paris where he passed the concept on to J. C. R. Licklider of M.I.T..^[33][34] Licklider, Vice President at Bolt Beranek and Newman, Inc., discussed a computer network in his January 1960 paper Man-Computer Symbiosis:^[35]
A network of such centers, connected to one another by wide-band communication lines [...] the functions of present-day libraries together with anticipated advances in information storage and retrieval and symbiotic functions suggested earlier in this paper
In August 1962, Licklider and Welden Clark published the paper "On-Line Man-Computer Communication"^[36] which was one of the first descriptions of a networked future.
In October 1962, Licklider was hired by Jack Ruina as director of the newly established Information Processing Techniques Office (IPTO) within DARPA, with a mandate to interconnect the United States Department of Defense's main computers at Cheyenne Mountain, the Pentagon, and SAC HQ. There he formed an informal group within DARPA to further computer research. He began by writing memos in 1963 describing a distributed network to the IPTO staff, whom he called "Members and Affiliates of the Intergalactic Computer Network".^[37]
Although he left the IPTO in 1964, five years before the ARPANET went live, it was his vision of universal networking that provided the impetus for one of his successors, Robert Taylor, to initiate the ARPANET development. Licklider later returned to lead the IPTO in 1973 for two years.^[38]
Development of packet switching
Main article: Packet switching
The issue of connecting separate physical networks to form one logical network was the first of many problems. Early networks used message switched systems that required rigid routing structures prone to single point of failure. In the 1960s, Paul Baran of the RAND Corporation produced a study of survivable networks for the U.S. military in the event of nuclear war.^[39] Information transmitted across Baran's network would be divided into what he called "message blocks".^[40] Independently, Donald Davies (National Physical Laboratory, UK), proposed and put into practice a local area network based on what he called packet switching, the term that would ultimately be adopted. Larry Roberts applied Davies' concepts of packet switching for the ARPANET wide area network,^[41][42] and sought input from Paul Baran. Leonard Kleinrock subsequently developed the mathematical theory behind the performance of this technology building on his earlier work on queueing theory.^[43]
Packet switching is a rapid store and forward networking design that divides messages up into arbitrary packets, with routing decisions made per-packet. It provides better bandwidth utilization and response times than the traditional circuit-switching technology used for telephony, particularly on resource-limited interconnection links.^[44]