(Original text from The Internet Society under CC-BY-NC-SA license and the World Wide Web Foundation, edited and expanded by Sofia Lemons.)
The Internet has revolutionized the computer and communications world like nothing before. The invention of the telegraph, telephone, radio, and computer set the stage for this unprecedented integration of capabilities. The Internet is at once a world-wide broadcasting capability, a mechanism for information dissemination, and a medium for collaboration and interaction between individuals and their computers without regard for geographic location. The Internet represents one of the most successful examples of the benefits of sustained investment and commitment to research and development of information infrastructure. Beginning with the early research in packet switching, the government, industry and academia have been partners in evolving and deploying this exciting new technology. Today, terms like "bleiner@computer.org" and "http://www.acm.org" trip lightly off the tongue of the random person on the street.
The history of the Internet revolves around four distinct aspects. There is the technological evolution that began with early research on packet switching and the ARPANET (the first functional "Internet"), and where current research continues to expand the horizons of the infrastructure along several dimensions, such as scale, performance, and higher-level functionality. There is the operations and management aspect of a global and complex operational infrastructure. There is the social aspect, which resulted in a broad community of Internauts working together to create and evolve the technology. And there is the commercialization aspect, resulting in an extremely effective transition of research results into a broadly deployed and available information infrastructure.
The Internet today is a widespread information infrastructure, the initial prototype of what is often called the National (or Global or Galactic) Information Infrastructure. Its history is complex and involves many aspects - technological, organizational, and community. And its influence reaches not only to the technical fields of computer communications but throughout society as we move toward increasing use of online tools to accomplish electronic commerce, information acquisition, and community operations.
The first recorded description of the social interactions that could be enabled through networking was a series of memos written by J.C.R. Licklider of MIT in August 1962 discussing his "Galactic Network" concept. He envisioned a globally interconnected set of computers through which everyone could quickly access data and programs from any site. In spirit, the concept was very much like the Internet of today. Licklider was the first head of the computer research program at ARPA (Advanced Research Projects Agency, a branch of the U.S. federal government), starting in October 1962. While at ARPA he convinced his successors Ivan Sutherland, Bob Taylor, and MIT researcher Lawrence G. Roberts, of the importance of this networking concept.
Leonard Kleinrock at MIT published the first paper on packet switching theory in July 1961 and the first book on the subject in 1964. Kleinrock convinced Roberts of the theoretical feasibility of communications using packets rather than circuits, which was a major step along the path towards computer networking. Packets are small, standardized portions of a message to be sent over a network. They are numbered so that the recipient can tell when a packet has been lost and can request the sender to re-send that packet, rather than having to send the whole message again. These allow any size of message to be sent reliably, and in a way that can recover if transmission is unreliable or needs to be rerouted.
Due to Kleinrock's early development of packet switching theory and his focus on analysis, design and measurement, his Network Measurement Center at UCLA was selected to be the first node on the ARPANET. All this came together in September 1969 when BBN installed the first IMP at UCLA and the first host computer was connected. Doug Engelbart's project on "Augmentation of Human Intellect" (which included NLS, an early hypertext system) at Stanford Research Institute (SRI) provided a second node. SRI supported the Network Information Center, led by Elizabeth (Jake) Feinler and including functions such as maintaining tables of host name to address mapping as well as a directory of the RFC's.
Computers were added quickly to the ARPANET during the following years, and work proceeded on completing a functionally complete Host-to-Host protocol and other network software. In December 1970 the Network Working Group (NWG) working under S. Crocker finished the initial ARPANET Host-to-Host protocol, called the Network Control Protocol (NCP). As the ARPANET sites completed implementing NCP during the period 1971-1972, the network users finally could begin to develop applications.
In October 1972, Kahn organized a large, very successful demonstration of the ARPANET at the International Computer Communication Conference (ICCC). This was the first public demonstration of this new network technology to the public. It was also in 1972 that the initial "hot" application, electronic mail (email), was introduced. In March Ray Tomlinson at BBN wrote the basic email message send and read software, motivated by the need of the ARPANET developers for an easy coordination mechanism. In July, Roberts expanded its utility by writing the first email utility program to list, selectively read, file, forward, and respond to messages. From there email took off as the largest network application for over a decade. This was a harbinger of the kind of activity we see on the World Wide Web today, namely, the enormous growth of all kinds of "people-to-people" traffic.
The original ARPANET grew into the Internet. Internet was based on the idea that there would be multiple independent networks of rather arbitrary design, beginning with the ARPANET as the pioneering packet switching network, but soon to include other networks. The Internet as we now know it embodies a key underlying technical idea, namely that of open architecture networking. In this approach, the choice of any individual network technology did not have to fit only one model but rather could be selected freely by a provider and made to work with the other networks through a meta-level "Internetworking Architecture". Up until that time there was only one general method for connecting networks. This was the traditional circuit switching method. While there were other limited ways to interconnect different networks, they required that one network be used as a component of the other, rather than acting as peers.
In an open-architecture network, the individual networks may be separately designed and developed and each may have its own unique interface which it may offer to users and/or other providers, including other Internet providers. Each network can be designed in accordance with the specific environment and user requirements of that network.
The idea of open-architecture networking was first introduced by Kahn shortly after having arrived at ARPA (then renamed DARPA) in 1972. At the time, the program was called "Internetting". Key to making the system work was a reliable end-end protocol that could maintain effective communication in the face of interference, or withstand intermittent blackout.
One limitation of the original Internet protocol was that it relied on ARPANET as a central controller to provide routes for messages and to ensure reliability. If any packets were lost, the protocol would come to a grinding halt. Thus, Kahn decided to develop a new version of the protocol which could meet the needs of an open-architecture network environment. This protocol would eventually be called the Transmission Control Protocol/Internet Protocol (TCP/IP).
Four ground rules were critical to Kahn's early thinking:
The original Cerf/Kahn paper on the Internet described one protocol, called TCP (Transmission Control Protocol), which provided all the transport and forwarding services in the Internet. Kahn had intended that the TCP protocol support a range of transport services, but later reorganized into two protocols, the simple IP (Internet Protocol) which provided only for addressing and forwarding of individual packets, and the separate TCP, which was concerned with service features such as flow control and recovery from lost packets. IP is the service which most users are at least passingly aware of, because IP addresses are used to identify and locate a computer on the Internet.
A major initial motivation for both the ARPANET and the Internet was resource sharing - for example allowing users on the networks to access the time sharing of large supercomputers attached to the ARPANET. Connecting the two together was far more economical that duplicating these very expensive systems. However, while file transfer and remote login (Telnet) were very important applications, electronic mail has probably had the most significant impact of the innovations from that era. Email provided a new model of how people could communicate with each other, and changed the nature of collaboration, first in the building of the Internet itself (as is discussed below) and later for much of society.
There were other applications proposed in the early days of the Internet, including packet based voice communication (the precursor of modern Voice over IP, or VOIP), various models of file and disk sharing, and early "worm" programs that showed the concept of agents (and, of course, viruses). A key concept of the Internet is that it was not designed for just one application, but as a general infrastructure on which new applications could be conceived, as illustrated later by the emergence of the World Wide Web. It is the general purpose nature of the service provided by TCP and IP that makes this possible.
DARPA let three contracts to Stanford (Cerf), BBN (Ray Tomlinson) and UCL (Peter Kirstein) to implement TCP/IP (it was simply called TCP in the Cerf/Kahn paper but contained both components). The Stanford team, led by Cerf, produced the detailed specification and within about a year there were three independent implementations of TCP that could interoperate.
This was the beginning of long term experimentation and development to evolve and mature the Internet concepts and technology. Beginning with the first three networks (ARPANET, Packet Radio, and Packet Satellite) and their initial research communities, the experimental environment grew to incorporate essentially every form of network and a very broad-based research and development community. With each expansion has come new challenges.
The early implementations of TCP were done for large time sharing systems for supercomputers, so researchers could have access to such computers without having to purchase and entire one of their own. When desktop computers first appeared, it was thought by some that TCP was too big and complex to run on a personal computer. David Clark and his research group at MIT set out to show that a compact and simple implementation of TCP was possible. They produced an implementation, first for the Xerox Alto (the early personal workstation developed at Xerox PARC) and then for the IBM PC. That implementation was fully interoperable with other TCPs, but was tailored to the application suite and performance objectives of the personal computer, and showed that workstations, as well as large time-sharing systems, could be a part of the Internet.
Widespread development of Local Area Networks (LANs), Personal Computers (PCs), and workstations in the 1980s allowed the Internet to flourish. Ethernet technology, developed by Bob Metcalfe at Xerox PARC in 1973, is now probably the dominant network technology in the Internet. This change from having a few networks with a modest number of time-shared hosts (the original ARPANET model) to having many networks has resulted in a number of new concepts and changes to the underlying technology.
A major shift occurred as a result of the increase in scale of the Internet and its associated management issues. To make it easy for people to use the network, hosts were assigned names, so that it was not necessary to remember the numeric addresses. Originally, there were a fairly limited number of hosts, so it was feasible to maintain a single table of all the hosts and their associated names and addresses. The shift to having a large number of independently managed networks (e.g., LANs) meant that having a single table of hosts was no longer feasible, and the Domain Name System (DNS) was invented by Paul Mockapetris of USC/ISI. The DNS permitted a scalable distributed mechanism for resolving human-readable host names (such as www.acm.org) into an IP address.
One of the more interesting challenges was the transition of the ARPANET host protocol from NCP to TCP/IP as of January 1, 1983. This was a "flag-day" style transition, requiring all hosts to convert simultaneously or be left out. This transition was carefully planned within the community over several years before it actually took place and went surprisingly smoothly (but resulted in a distribution of buttons saying "I survived the TCP/IP transition").
TCP/IP was adopted as a defense standard three years earlier in 1980. This enabled defense to begin sharing in the DARPA Internet technology base and led directly to the eventual splitting of the military and non-military communities. By 1983, ARPANET was being used by a significant number of defense R&D and operational organizations. The transition of ARPANET from NCP to TCP/IP permitted it to be split into a MILNET supporting operational requirements and an ARPANET supporting research needs.
Thus, by 1985, Internet was already well established as a technology supporting a broad community of researchers and developers, and was beginning to be used by other communities for daily computer communications. Electronic mail was being used broadly across several communities, often with different systems.
At the same time that the Internet technology was being experimentally validated and widely used amongst a subset of computer science researchers, other networks and networking technologies were being pursued. The usefulness of computer networking - especially electronic mail - demonstrated by DARPA and Department of Defense contractors on the ARPANET was not lost on other communities and disciplines, so that by the mid-1970s computer networks had begun to spring up wherever funding could be found for the purpose. The U.S. Department of Energy (DoE) established MFENet for its researchers in Magnetic Fusion Energy, and DoE's High Energy Physicists responded by building HEPNet. NASA Space Physicists followed with SPAN, and Rick Adrion, David Farber, and Larry Landweber established CSNET for the (academic and industrial) Computer Science community with an initial grant from the U.S. National Science Foundation (NSF). AT&T's free-wheeling dissemination of the UNIX computer operating system spawned USENET, and in 1981 Ira Fuchs and Greydon Freeman devised BITNET, which linked academic mainframe computers.
With the exception of BITNET and USENET, these early networks (including ARPANET) were purpose-built - i.e., they were intended for, and largely restricted to, closed communities of scholars; there was hence little pressure for the individual networks to be compatible and, indeed, they largely were not. In addition, alternate technologies were being pursued in the commercial sector, including XNS from Xerox, DECNet, and IBM's SNA. It remained for the British JANET (1984) and U.S. NSFNET (1985) programs to explicitly announce their intent to serve the entire higher education community, regardless of discipline. Indeed, a condition for a U.S. university to receive NSF funding for an Internet connection was that "... the connection must be made available to ALL qualified users on campus."
In addition to the selection of TCP/IP for the NSFNET program, Federal agencies made and implemented several other policy decisions which shaped the Internet of today.
The NSF programs had such an impact on the formation of the Internet that by 1990 when the ARPANET itself was finally decommissioned, TCP/IP had supplanted or marginalized most other wide-area computer network protocols worldwide.
A key to the rapid growth of the Internet has been the free and open access to the basic documents, especially the specifications of the protocols.
The beginnings of the ARPANET and the Internet in the university research community promoted the academic tradition of open publication of ideas and results. However, the normal cycle of traditional academic publication was too formal and too slow for the dynamic exchange of ideas essential to creating networks.
In 1969 a key step was taken by S. Crocker (then at UCLA) in establishing the Request for Comments (or RFC) series of notes. These memos were intended to be an informal fast distribution way to share ideas with other network researchers. At first the RFCs were printed on paper and distributed via snail mail. As the File Transfer Protocol (FTP) came into use, the RFCs were prepared as online files and accessed via FTP. Now, of course, the RFCs are easily accessed via the World Wide Web at dozens of sites around the world.
The effect of the RFCs was to create a positive feedback loop, with ideas or proposals presented in one RFC triggering another RFC with additional ideas, and so on. When some consensus (or a least a consistent set of ideas) had come together a specification document would be prepared. Such a specification would then be used as the base for implementations by the various research teams. The RFCs are now viewed as the "documents of record" in the Internet engineering and standards community.
The open access to the RFCs (for free, if you have any kind of a connection to the Internet) promotes the growth of the Internet because it allows the actual specifications to be used for examples in college classes and by entrepreneurs developing new systems.
As the current rapid expansion of the Internet is fueled by the realization of its capability to promote information sharing, we should understand that the network's first role in information sharing was sharing the information about its own design and operation through the RFC documents. This unique method for evolving new capabilities in the network will continue to be critical to future evolution of the Internet.
Commercialization of the Internet involved not only the development of competitive, private network services, but also the development of commercial products implementing the Internet technology. In the early 1980s, dozens of vendors were incorporating TCP/IP into their products because they saw buyers for that approach to networking. Unfortunately they lacked both real information about how the technology was supposed to work and how the customers planned on using this approach to networking. The Department of Defense had mandated the use of TCP/IP in many of its purchases but gave little help to the vendors regarding how to build useful TCP/IP products.
In 1985, recognizing this lack of information availability and appropriate training, Dan Lynch in cooperation with the IAB arranged to hold a three day workshop for ALL vendors to come learn about how TCP/IP worked and what it still could not do well. The speakers came mostly from the DARPA research community who had both developed these protocols and used them in day-to-day work. About 250 vendor personnel came to listen to 50 inventors and experimenters. The results were surprises on both sides: the vendors were amazed to find that the inventors were so open about the way things worked (and what still did not work) and the inventors were pleased to listen to new problems they had not considered, but were being discovered by the vendors in the field. Thus a two-way discussion was formed that has lasted for over a decade.
After two years of conferences, tutorials, design meetings and workshops, a special event was organized that invited those vendors whose products ran TCP/IP well enough to come together in one room for three days to show off how well they all worked together and also ran over the Internet. In September of 1988 the first Interop trade show was born. 50 companies made the cut. 5,000 engineers from potential customer organizations came to see if it all did work as was promised. It did. Why? Because the vendors worked extremely hard to ensure that everyone's products interoperated with all of the other products - even with those of their competitors.
In parallel with the commercialization efforts that were highlighted by the Interop activities, the vendors began to attend the Internet Engineering Task Force (IETF) meetings that were held 3 or 4 times a year to discuss new ideas for extensions of the TCP/IP protocol suite. Starting with a few hundred attendees mostly from academia and paid for by the government, these meetings now often exceed a thousand attendees, mostly from the vendor community and paid for by the attendees themselves. This self-selected group evolves the TCP/IP suite in a mutually cooperative manner. The reason it is so useful is that it is composed of all stakeholders: researchers, end users and vendors.
Originally, commercial efforts mainly comprised vendors providing the basic networking products, and service providers offering the connectivity and basic Internet services. The Internet has now become a "commodity" service, and much of the attention has been on the use of this global information infrastructure for support of other commercial services. This has been tremendously accelerated by the widespread and rapid adoption of browsers and the World Wide Web technology, allowing users easy access to information linked throughout the globe. Products are available to facilitate the provisioning of that information and many of the latest developments in technology have been aimed at providing increasingly sophisticated information services on top of the basic Internet data communications.
In March 1989, Tim Berners-Lee (then a software engineer at CERN, the European Organization for Nuclear Research) laid out his vision for what would become the World-Wide Web in a document called “Information Management: A Proposal”. Believe it or not, this initial proposal was not immediately accepted. In fact, his boss at the time, Mike Sendall, noted the words “Vague but exciting” on the cover. The Web was never an official CERN project, but Sendall managed to give Berners-Lee time to work on it in September 1990.
By October of 1990, Berners-Lee had written the three fundamental technologies that remain the foundation of today’s Web (and which you may have seen appear on parts of your Web browser):
Berners-Lee also wrote the first Web page editor/browser (“WorldWideWeb.app”) and the first Web server (“httpd“). By the end of 1990, the first Web page was served on the open Internet, and in 1991, people outside of CERN were invited to join this new Web community.
As the Web began to grow, Berners-Lee realized that its true potential would only be unleashed if anyone, anywhere could use it without paying a fee or having to ask for permission. He explains: “Had the technology been proprietary, and in my total control, it would probably not have taken off. You can’t propose that something be a universal space and at the same time keep control of it.”
He and others advocated to ensure that CERN would agree to make the underlying code available on a royalty-free basis, for ever. This decision was announced in April 1993, and sparked a global wave of creativity, collaboration and innovation never seen before. In 2003, the companies developing new Web standards committed to a Royalty Free Policy for their work. In 2014, the year we celebrated the Web’s 25th birthday, almost two in five people around the world were using it.
The early Web community produced some revolutionary ideas that are now spreading far beyond the technology sector:
On October 24, 1995, the FNC unanimously passed a resolution defining the term Internet. This definition was developed in consultation with members of the Internet and intellectual property rights communities. RESOLUTION: The Federal Networking Council (FNC) agrees that the following language reflects our definition of the term "Internet". "Internet" refers to the global information system that -- (i) is logically linked together by a globally unique address space based on the Internet Protocol (IP) or its subsequent extensions/follow-ons; (ii) is able to support communications using the Transmission Control Protocol/Internet Protocol (TCP/IP) suite or its subsequent extensions/follow-ons, and/or other IP-compatible protocols; and (iii) provides, uses or makes accessible, either publicly or privately, high level services layered on the communications and related infrastructure described herein.
The Internet has changed much since it came into existence. It was conceived in the era of time-sharing, but has survived into the era of personal computers, client-server and peer-to-peer computing, and the network computer. It was designed before LANs existed, but has accommodated that new network technology. It was envisioned as supporting a range of functions from file sharing and remote login to resource sharing and collaboration, and has spawned electronic mail and more recently the World Wide Web. But most important, it started as the creation of a small band of dedicated researchers, and has grown to be a commercial success with billions of dollars of annual investment.
One should not conclude that the Internet has now finished changing. The Internet, although a network in name and geography, is a creature of the computer, not the traditional network of the telephone or television industry. It will, indeed it must, continue to change and evolve at the speed of the computer industry if it is to remain relevant.
The availability of pervasive networking (i.e., the Internet) along with powerful affordable computing and communications in portable form (i.e., laptop computers, two-way pagers, PDAs, cell phones), is making possible a new paradigm of nomadic computing and communications. This evolution has brought us new applications - Internet telephone and Internet television, to name two. It is evolving to permit more sophisticated forms of pricing and cost recovery, a perhaps painful requirement in this commercial world. It has changed to accommodate yet another generation of underlying network technologies with different characteristics and requirements, e.g. broadband residential access and satellites. New modes of access and new forms of service will spawn new applications, which in turn will drive further evolution of the net itself.
The most pressing question for the future of the Internet is not how the technology will change, but how the process of change and evolution itself will be managed. As this paper describes, the architecture of the Internet has always been driven by a core group of designers, but the form of that group has changed as the number of interested parties has grown. With the success of the Internet has come a proliferation of stakeholders - stakeholders now with an economic as well as an intellectual investment in the network. At times, the industry struggles to find the economic rationale for the large investment needed for the future growth, for example to upgrade residential access for smaller populations of users. If the Internet stumbles, it will not be because we lack for technology, vision, or motivation. It will be because we cannot set a direction and march collectively into the future.
(Image from http://cs205sp14.wikidot.com/introduction-to-the-Internet)