Internet
computer network
Internet, a system architecture that has revolutionized communications and methods of commerce by allowing various computer networks around the world to interconnect. Sometimes referred to as a “network of networks,” the Internet emerged in the United States in the 1970s but did not become visible to the general public until the early 1990s. By 2020, approximately 4.5 billion people, or more than half of the world’s population, were estimated to have access to the Internet.
The Internet consists of technologies developed by different individuals and organizations. Important figures include Robert W. Taylor, who led the development of the ARPANET (an early prototype of the Internet), and Vinton Cerf and Robert Kahn, who developed the Transmission Control Protocol/Internet Protocol (TCP/IP) technologies.
Origin And Development
Early networks
The first computer networks were dedicated special-purpose systems such as SABRE (an airline reservation system) and AUTODIN I (a defense command-and-control system), both designed and implemented in the late 1950s and early 1960s. By the early 1960s computer manufacturers had begun to use semiconductor technology in commercial products, and both conventional batch-processing and time-sharing systems were in place in many large, technologically advanced companies. Time-sharing systems allowed a computer’s resources to be shared in rapid succession with multiple users, cycling through the queue of users so quickly that the computer appeared dedicated to each user’s tasks despite the existence of many others accessing the system “simultaneously.” This led to the notion of sharing computer resources (called host computers or simply hosts) over an entire network. Host-to-host interactions were envisioned, along with access to specialized resources (such as supercomputers and mass storage systems) and interactive access by remote users to the computational powers of time-sharing systems located elsewhere. These ideas were first realized in ARPANET, which established the first host-to-host network connection on October 29, 1969. It was created by the Advanced Research Projects Agency (ARPA) of the U.S. Department of Defense. ARPANET was one of the first general-purpose computer networks. It connected time-sharing computers at government-supported research sites, principally universities in the United States, and it soon became a critical piece of infrastructure for the computer science research community in the United States. Tools and applications—such as the simple mail transfer protocol (SMTP, commonly referred to as e-mail), for sending short messages, and the file transfer protocol (FTP), for longer transmissions—quickly emerged. In order to achieve cost-effective interactive communications between computers, which typically communicate in short bursts of data, ARPANET employed the new technology of packet switching. Packet switching takes large messages (or chunks of computer data) and breaks them into smaller, manageable pieces (known as packets) that can travel independently over any available circuit to the target destination, where the pieces are reassembled. Thus, unlike traditional voice communications, packet switching does not require a single dedicated circuit between each pair of users.
DARPA (Defense Advanced Research Projects Agency; formerly ARPA) supported initiatives for ground-based and satellite-based packet networks. The ground-based packet radio system provided mobile access to computing resources, while the packet satellite network connected the United States with several European countries and enabled connections with widely dispersed and remote regions. With the introduction of packet radio, connecting a mobile terminal to a computer network became feasible. However, time-sharing systems were then still too large, unwieldy, and costly to be mobile or even to exist outside a climate-controlled computing environment. A strong motivation thus existed to connect the packet radio network to ARPANET in order to allow mobile users with simple terminals to access the time-sharing systems for which they had authorization. Similarly, the packet satellite network was used by DARPA to link the United States with satellite terminals serving the United Kingdom, Norway, Germany, and Italy. These terminals, however, had to be connected to other networks in European countries in order to reach the end users. Thus arose the need to connect the packet satellite net, as well as the packet radio net, with other networks.
Foundation of the Internet
The Internet resulted from the effort to connect various research networks in the United States and Europe. First, DARPA established a program to investigate the interconnection of “heterogeneous networks.” This program, called Internetting, was based on the newly introduced concept of open architecture networking, in which networks with defined standard interfaces would be interconnected by “gateways.” A working demonstration of the concept was planned. In order for the concept to work, a new protocol had to be designed and developed; indeed, a system architecture was also required.
In 1974 Vinton Cerf, then at Stanford University in California, and this author, then at DARPA, collaborated on a paper that first described such a protocol and system architecture—namely, the transmission control protocol (TCP), which enabled different types of machines on networks all over the world to route and assemble data packets. TCP, which originally included the Internet protocol (IP), a global addressing mechanism that allowed routers to get data packets to their ultimate destination, formed the TCP/IP standard, which was adopted by the U.S. Department of Defense in 1980. By the early 1980s the “open architecture” of the TCP/IP approach was adopted and endorsed by many other researchers and eventually by technologists and businessmen around the world.
By the 1980s other U.S. governmental bodies were heavily involved with networking, including the National Science Foundation (NSF), the Department of Energy, and the National Aeronautics and Space Administration (NASA). While DARPA had played a seminal role in creating a small-scale version of the Internet among its researchers, NSF worked with DARPA to expand access to the entire scientific and academic community and to make TCP/IP the standard in all federally supported research networks. In 1985–86 NSF funded the first five supercomputing centres—at Princeton University, the University of Pittsburgh, the University of California, San Diego, the University of Illinois, and Cornell University. In the 1980s NSF also funded the development and operation of the NSFNET, a national “backbone” network to connect these centres. By the late 1980s the network was operating at millions of bits per second. NSF also funded various nonprofit local and regional networks to connect other users to the NSFNET. A few commercial networks also began in the late 1980s; these were soon joined by others, and the Commercial Internet Exchange (CIX) was formed to allow transit traffic between commercial networks that otherwise would not have been allowed on the NSFNET backbone. In 1995, after extensive review of the situation, NSF decided that support of the NSFNET infrastructure was no longer required, since many commercial providers were now willing and able to meet the needs of the research community, and its support was withdrawn. Meanwhile, NSF had fostered a competitive collection of commercial Internet backbones connected to one another through so-called network access points (NAPs).
From the Internet’s origin in the early 1970s, control of it steadily devolved from government stewardship to private-sector participation and finally to private custody with government oversight and forbearance. Today a loosely structured group of several thousand interested individuals known as the Internet Engineering Task Force participates in a grassroots development process for Internet standards. Internet standards are maintained by the nonprofit Internet Society, an international body with headquarters in Reston, Virginia. The Internet Corporation for Assigned Names and Numbers (ICANN), another nonprofit, private organization, oversees various aspects of policy regarding Internet domain names and numbers.
Commercial expansion
The rise of commercial Internet services and applications helped to fuel a rapid commercialization of the Internet. This phenomenon was the result of several other factors as well. One important factor was the introduction of the personal computer and the workstation in the early 1980s—a development that in turn was fueled by unprecedented progress in integrated circuit technology and an attendant rapid decline in computer prices. Another factor, which took on increasing importance, was the emergence of Ethernet and other “local area networks” to link personal computers. But other forces were at work too. Following the restructuring of AT&T in 1984, NSF took advantage of various new options for national-level digital backbone services for the NSFNET. In 1988 the Corporation for National Research Initiatives received approval to conduct an experiment linking a commercial e-mail service (MCI Mail) to the Internet. This application was the first Internet connection to a commercial provider that was not also part of the research community. Approval quickly followed to allow other e-mail providers access, and the Internet began its first explosion in traffic.
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