The Internet provides a capability so powerful and general that it can be used for almost any purpose that depends on information, and it is accessible by every individual who connects to one of its constituent networks. It supports human communication via social media,  (e-mail), “chat rooms,” newsgroups, and audio and video transmission and allows people to work collaboratively at many different locations. It supports access to digital information by many applications, including the World Wide Web. The Internet has proved to be a spawning ground for a large and growing number of “e-businesses” (including subsidiaries of traditional “brick-and-mortar” companies) that carry out most of their sales and services over the Internet.

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 defence. 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.

Commercial packet networks were introduced in the 1970s, but these were designed principally to provide efficient access to remote computers by dedicated terminals. Briefly, they replaced long-distance modem connections by less-expensive “virtual” circuits over packet networks. In the United States, Telenet and Tymnet were two such packet networks. Neither supported host-to-host communications; in the 1970s this was still the province of the research networks, and it would remain so for many years.

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 Vinten Cerf, then at Standford Universities 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 US Department of defence 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 Aeronautica And Space Research (NASA). While DARPA had played 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—Princeton University, the University of Pittsberg , and Cornell University. In the 1980s NSF also funded the development and operation of 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 PC 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 services (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.

In 1993 federal legislation allowed NSF to open the NSFNET backbone to commercial users. Prior to that time, use of the backbone was subject to an “acceptable use” policy, established and administered by NSF, under which commercial use was limited to those applications that served the research community. NSF recognized that commercially supplied network services, now that they were available, would ultimately be far less expensive than continued funding of special-purpose network services.

Also in 1993 the University of Illinois made widely available Mosaic, a new type of computer program, known as a browser, that ran on most types of computers and, through its “point-and-click” interface, simplified access, retrieval, and display of files through the Internet. Mosaic incorporated a set of access protocols and display standards originally developed at the European Organization for Nuclear Research  for a new Internet application called the WWW. In 1994 NETSCAPE COMMUNICATION CORPORATION (originally called Mosaic Communications Corporation) was formed to further develop the Mosaic browser and server software for commercial use. Shortly thereafter, the software giant Microsoft Corporation became interested in supporting Internet applications on personal computers (PCs) and developed its Internet Explorer Web browser (based initially on Mosaic) and other programs. These new commercial capabilities accelerated the growth of the Internet, which as early as 1988 had already been growing at the rate of 100 percent per year.

By the late 1990s there were approximately 10,000 ISPs around the world, more than half located in the United States. However, most of these ISPs provided only local service and relied on access to regional and national ISPs for wider connectivity. Consolidation began at the end of the decade, with many small to medium-size providers merging or being acquired by larger ISPs. Among these larger providers were groups such as  AOL, which started as a dial-up information service with no Internet connectivity but made a transition in the late 1990s to become the leading provider of Internet services in the world—with more than 25 million subscribers by 2000 and with branches in Australia, Europe, South America, and Asia. Widely used Internet “portals” such as AOL, Yahoo, Excite, and others were able to command advertising fees owing to the number of “eyeballs” that visited their sites. Indeed, during the late 1990s advertising revenue became the main quest of many Internet sites, some of which began to speculate by offering free or low-cost services of various kinds that were visually augmented with advertisements. By 2001 this speculative bubble had burst.

The 21st century and future directions

After the collapse of the Internet bubble came the emergence of what was called “Web 2.0,” an Internet with emphasis on social networking and content generated by users, and cloud computing. Social media services such as Facebook, Twitter, and Instagram became some of the most popular Internet sites through allowing users to share their own content with their friends and the wider world. Mobile phones became able to access the Web, and, with the introduction of smartphones like Apple’s iPhone (introduced in 2007), the number of Internet users worldwide exploded from about one-sixth of the world population in 2005 to more than half in 2020.

The increased availability of wireless access enabled applications that were previously uneconomical. For example, global positioning systems (GPS) combined with wireless Internet access help mobile users to locate alternate routes, generate precise accident reports and initiate recovery services, and improve traffic management and congestion control. In addition to smartphones, wireless laptop computers, and personal digital assistants (PDAs), wearable devices with voice input and special display glasses were developed.

While the precise structure of the future Internet is not yet clear, many directions of growth seem apparent. One is toward higher backbone and network access speeds. Backbone data rates of 100 billion bits (100 gigabits) per second are readily available today, but data rates of 1 trillion bits (1 terabit) per second or higher will eventually become commercially feasible. If the development of computer hardware, software, applications, and local access keeps pace, it may be possible for users to access networks at speeds of 100 gigabits per second. At such data rates, high-resolution video—indeed, multiple video streams—would occupy only a small fraction of available bandwidth. Remaining bandwidth could be used to transmit auxiliary information about the data being sent, which in turn would enable rapid customization of displays and prompt resolution of certain local queries. Much research, both public and private, has gone into integrated broadband systems that can simultaneously carry multiple signals—data, voice, and video. In particular, the U.S. government has funded research to create new high-speed network capabilities dedicated to the scientific-research community.

It is clear that communications connectivity will be an important function of a future Internet as more machines and devices are interconnected. In 1998, after four years of study, the Internet Engineering Task Force published a new 128-bit IP address standard intended to replace the conventional 32-bit standard. By allowing a vast increase in the number of available addresses (2¹²⁸, as opposed to 2³²), this standard makes it possible to assign unique addresses to almost every electronic device imaginable. Thus, through the “Internet of things,” in which all machines and devices could be connected to the Internet, the expressions “wired” office, home, and car may all take on new meanings, even if the access is really wireless.

The dissemination of the digitized text, pictures, and audio and video recordings over the Internet, primarily available today through the World Wide Web, has resulted in an information explosion. Clearly, powerful tools are needed to manage network-based information. The information available on the Internet today may not be available tomorrow without careful attention being paid to preservation and archiving techniques. The key to making information persistently available is infrastructure and the management of that infrastructure. Repositories of information, stored as digital objects, will soon populate the Internet. At first these repositories may be dominated by digital objects specifically created and formatted for the World Wide Web, but in time they will contain objects of all kinds in formats that will be dynamically resolvable by users’ computers in real-time. The movement of digital objects from one repository to another will still leave them available to users who are authorized to access them, while replicated instances of objects in multiple repositories will provide alternatives to users who are better able to interact with certain parts of the Internet than with others. Information will have its own identity and, indeed, become a “first-class citizen” on the Internet.