Although the history of the Internet arguably begins in the 19th century with the invention of the telegraph system, the modern history of the Internet starts in the 1950s and 1960s with the development of computers. This began with point-to-point communication between mainframe computers and terminals, expanded to point-to-point connections between computers and then early research into packet switching. Packet switched networks such as ARPANET, Mark I at NPL in the UK, CYCLADES, Merit Network, Tymnet, and Telenet, were developed in the late 1960s and early 1970s using a variety of protocols. The ARPANET in particular lead to the development of protocols for internetworking, where multiple separate networks could be joined together into a network of networks.
In 1982 the Internet Protocol Suite (TCP/IP) was standardized and the concept of a world-wide network of fully interconnected TCP/IP networks called the Internet was introduced. Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) developed the Computer Science Network (CSNET) and again in 1986 when NSFNET provided access to supercomputer sites in the United States from research and education organizations. The ARPANET was decommissioned in 1990. Commercial internet service providers (ISPs) began to emerge in the late 1980s and 1990s and the Internet was commercialized in 1995 when NSFNET was decommissioned, removing the last restrictions on the use of the Internet to carry commercial traffic.
Since the mid-1990s the Internet has had a drastic impact on culture and commerce, including the rise of near instant communication by electronic mail, text based discussion forums, and the World Wide Web. The research and education community continues to use advanced networks such as NSF's very high speed Backbone Network Service (vBNS) and Internet2. Increasing amounts of data are transmitted at higher and higher speeds over fiber optic networks operating at 1-Gbps, 10-Gbps, or more. The Internet continues to grow, driven by ever greater amounts of online information and knowledge, by commerce and entertainment, and by social networking.
Precursors
The Internet has precursors that date back to the 19th century, especially the telegraph system, more than a century before the digital Internet became widely used in the second half of the 1990s. The concept of data communication - transmitting data between two different places, connected via some kind of electromagnetic medium, such as radio or an electrical wire - predates the introduction of the first computers. Such communication systems were typically limited to point to point communication between two end devices. Telegraph systems and telex machines can be considered early precursors of this kind of communication.
Early computers used the technology available at the time to allow communication between the central processing unit and remote terminals. As the technology evolved, new systems were devised to allow communication over longer distances (for terminals) or with higher speed (for interconnection of local devices) that were necessary for the mainframe computer model. Using these technologies it was possible to exchange data (such as files) between remote computers. However, the point to point communication model was limited, as it did not allow for direct communication between any two arbitrary systems; a physical link was necessary. The technology was also deemed as inherently unsafe for strategic and military use, because there were no alternative paths for the communication in case of an enemy attack.
Three terminals and an ARPA
In the 1950s and early 1960s, before the widespread inter-networking that led to the Internet, most communication networks were limited in that they only allowed communications between the stations on the network. Some networks had gateways or bridges between them, but these bridges were often limited or built specifically for a single use. One prevalent computer networking method was based on the central mainframe method, simply allowing its terminals to be connected via long leased lines. This method was used in the 1950s by Project RAND to support researchers such as Herbert Simon, at Carnegie Mellon University in Pittsburgh, Pennsylvania, when collaborating across the continent with researchers in Sullivan, Illinois, on automated theorem proving and artificial intelligence.
A fundamental pioneer in the call for a global network, J.C.R. Licklider, articulated the ideas in his January 1960 paper, Man-Computer Symbiosis.
"A network of such [computers], connected to one another by wide-band communication lines [which provided] the functions of present-day libraries together with anticipated advances in information storage and retrieval and [other] symbiotic functions."—J.C.R. Licklider,
In August 1962, Licklider and Welden Clark published the paper "On-Line Man Computer Communication", 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 describing a distributed network to the IPTO staff, whom he called "Members and Affiliates of the Intergalactic Computer Network". As part of the information processing office's role, three network terminals had been installed: one for System Development Corporation in Santa Monica, one for Project Genie at the University of California, Berkeley and one for the Compatible Time-Sharing System project at the Massachusetts Institute of Technology (MIT). Licklider's identified need for inter-networking would be made obvious by the apparent waste of resources this caused.
"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, it's obvious what to do (But I don't want to do it): If you have these three terminals, there ought to be one terminal that goes anywhere you want to go where you have interactive computing. That idea is the ARPAnet."
—Robert W. Taylor, co-writer with Licklider of "The Computer as a Communications Device", in an interview with The New York Times,
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 that led his successors such as Lawrence Roberts and Robert Taylor to further the ARPANET development. Licklider later returned to lead the IPTO in 1973 for two years.[3]
Packet switching
At the tip of the problem lay the issue of connecting separate physical networks to form one logical network. During the 1960s, Paul Baran (RAND Corporation), produced a study of survivable networks for the US military. Information transmitted across Baran's network would be divided into what he called 'message-blocks'. Independently, Donald Davies (National Physical Laboratory, UK), proposed and developed a similar network based on what he called packet-switching, the term that would ultimately be adopted. Leonard Kleinrock (MIT) developed mathematical theory behind this technology. Packet-switching provides better bandwidth utilization and response times than the traditional circuit-switching technology used for telephony, particularly on resource-limited interconnection links.
Packet switching is a rapid store-and-forward networking design that divides messages up into arbitrary packets, with routing decisions made per-packet. Early networks used message switched systems that required rigid routing structures prone to single point of failure. This led Tommy Krash and Paul Baran's U.S. military funded research to focus on using message-blocks to include network redundancy, which in turn led to the widespread urban legend that the Internet was designed to resist nuclear attack.
Networks that led to the Internet
ARPANET
Promoted to the head of the information processing office at DARPA, Robert Taylor intended to realize Licklider's ideas of an interconnected networking system. Bringing in Larry Roberts from MIT, he initiated a project to build such a network. The first ARPANET link was established between the University of California, Los Angeles and the Stanford Research Institute on 22:30 hours on October 29, 1969.
"We set up a telephone connection between us and the guys at SRI...", Kleinrock ... said in an interview: "We typed the L and we asked on the phone,
Yet a revolution had begun"....
- "Do you see the L?"
- "Yes, we see the L," came the response.
- We typed the O, and we asked, "Do you see the O."
- "Yes, we see the O."
- Then we typed the G, and the system crashed...
By December 5, 1969, a 4-node network was connected by adding the University of Utah and the University of California, Santa Barbara. Building on ideas developed in ALOHAnet, the ARPANET grew rapidly. By 1981, the number of hosts had grown to 213, with a new host being added approximately every twenty days.
ARPANET became the technical core of what would become the Internet, and a primary tool in developing the technologies used. ARPANET development was centered around the Request for Comments (RFC) process, still used today for proposing and distributing Internet Protocols and Systems. RFC 1, entitled "Host Software", was written by Steve Crocker from the University of California, Los Angeles, and published on April 7, 1969. These early years were documented in the 1972 film Computer Networks: The Heralds of Resource Sharing.
International collaborations on ARPANET were sparse. For various political reasons, European developers were concerned with developing the X.25 networks. Notable exceptions were the Norwegian Seismic Array (NORSAR) in 1972, followed in 1973 by Sweden with satellite links to the Tanum Earth Station and Peter Kirstein's research group in the UK, initially at the Institute of Computer Science, London University and later at University College London.[12]
NPL
In 1965, Donald Davies of the National Physical Laboratory (United Kingdom) proposed a national data network based on packet-switching. The proposal was not taken up nationally, but by 1970 he had designed and built the Mark I packet-switched network to meet the needs of the multidisciplinary laboratory and prove the technology under operational conditions. By 1976 12 computers and 75 terminal devices were attached and more were added until the network was replaced in 1986.
Merit Network
The Merit Network[14] was formed in 1966 as the Michigan Educational Research Information Triad to explore computer networking between three of Michigan's public universities as a means to help the state's educational and economic development. With initial support from the State of Michigan and the National Science Foundation (NSF), the packet-switched network was first demonstrated in December 1971 when an interactive host to host connection was made between the IBM mainframe computer systems at the University of Michigan in Ann Arbor and Wayne State University in Detroit. In October 1972 connections to the CDC mainframe at Michigan State University in East Lansing completed the triad. Over the next several years in addition to host to host interactive connections the network was enhanced to support terminal to host connections, host to host batch connections (remote job submission, remote printing, batch file transfer), interactive file transfer, gateways to the Tymnet and Telenet public data networks, X.25 host attachments, gateways to X.25 data networks, Ethernet attached hosts, and eventually TCP/IP and additional public universities in Michigan join the network. All of this set the stage for Merit's role in the NSFNET project starting in the mid-1980s.
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