Internet

Introduction
The Internet is a distributed, interoperable, packet-switched network. These characteristics enables millions of private and public computers around the world to communicate with each other. This interconnection of multiple computer networks, which otherwise would function only as a series of independent and isolated islands, gives rise to the term “Internet” as we know it today.

Pre-Internet Networks
Earlier computer networks were centrally “switched,” so that all messages between any two points on the network were sent through the central switching computer. These networks are today called “star” networks, because there is a central point in the network &mdash; the central switching computer &mdash; that has wires “radiating” out to all other computers. Though all computer networks of the time were “star” shaped in their architecture, different switching technologies were often employed by each of them.

In the early 1960’s, the Department of Defense, like other computer network users, relied on star-shaped networks for military communication. The DoD understood, however, that those networks had at least two problems. First was that they were highly vulnerable. Anything that rendered the central switching computer inoperative &mdash; whether a bomb, sabotage, or just “down time” &mdash; would simultaneously render the entire network inoperative. Second, because different star networks used different technologies for switching messages internally, they could not communicate with each other. Messages were confined to the network from which they originated.

In 1964, a researcher at the Rand Corporation, Paul Baran, designed a computer-communications network that had no hub, no central switching station, and no governing authority. In this system, each message was cut into tiny strips and stuffed into "electronic envelopes" called packets. each marked with the address of the sender and the intended receiver. The packets were then released like confetti into the web of interconnected computers, where they were tossed back and forth over high-speed wires in the general direction of their destination and reassembled when they arrived. Baran's packet switching network, as it came to be called, became the technological underpinnings of the Internet.

Development of the Internet
The Internet developed out of research efforts funded by the U.S. Department of Defense Advanced Research Projects Agency (DARPA) (later renamed "ARPA") in the 1960s and 1970s to create and test interconnected computer networks that would not have the two drawbacks noted above. ARPA created a standard format for electronic messages that could be used between networks to connect them in spite of internal differences; and it devised an interconnection method that was based on many decentralized switching computers. Any given message would not travel over a fixed path to a central computer. Rather, it would be “switched” among many different computers until it reached its destination. The network designers set a limit on the size of a single message. If longer than that limit, a message would be broken up into smaller pieces called “packets” that would each be routed individually. This new type of network switching was called “packet switching.”

By creating a system that relied on many decentralized computers to handle message routing, rather than one central computer as was the method for star-shaped networks, ARPA produced a network that could still operate even if many of its individual computers malfunctioned or were damaged. ARPA implemented a prototype network called “ARPANET” to test out and continue development of this new technology.

By the mid-1970s, computer scientists had developed several software communications standards &mdash; or protocols &mdash; for connecting computers within the same network. At about the same time, ARPANET scientists developed a protocol for connecting different networks to each other, called the Transmission Control Protocol/Internet Protocol (“TCP/IP”) software suite. This approach requires that individual networks be connected together by gateway interface devices, called switches or routers. Thus, interconnected networks are, in effect, a series of routers connected by transmission links. Packets of data are passed from one router to another, via the transmission links.

Throughout the 1970s and 1980s, the interconnection of computer networks using TCP/IP continued to grow, spurred by uses such as e-mail.

Unrelated to ARPA’s work on this packet switching technology, at about the same time the National Science Foundation (NSF) funded the creation of several supercomputer sites around the country. There were far fewer supercomputers than scientists and researchers interested in using them. NSF understood that it would be important to find ways for researchers to use these computers “remotely,” that is, without having to travel physically to the supercomputer site. NSF was aware of the work going on with the ARPANET, and determined that that network might provide the sort of access methods needed to link researchers to the supercomputers.

The military portion of ARPANET was integrated into the Defense Data Network in the early 1980s. In 1985, NSF announced a plan to connect one hundred universities to the Internet, in addition to five already-existing supercomputer centers located around the country. Recognizing the increasing importance of this interconnected network to U.S. competitiveness in the sciences, however, NSF embarked on a new program with the goal of extending Internet access to every science and engineering researcher in the country.

In 1988, NSF, in conjunction with a consortium of private-sector organizations, completed a new long-distance, wide-area network, dubbed the “NSFNET” backbone. Although private entities were now involved in extending the Internet, its design still reflected ARPANET’s original goals. NSFNET connected a variety of local university networks and hence enabled nationwide access to the new supercomputer centers. The idea of calling this sort of network an “Internet” reflects the fact that its first use was conceived primarily to allow an interconnection among existing incompatible networks; in its early incarnations, the Internet was viewed less as a “network” for its own sake, in other words, and more as a means to connect other networks together.

ARPANET was taken out of service in 1990, but by that time NSFNET had supplanted ARPANET as a national backbone for an "Internet" of worldwide interconnected networks. ARPANET's influence continued because TCP/IP has replaced most other wide-area computer network protocols, and because its design, which provided for generality and flexibility, proved to be durable in a number of contexts. At the same time, its successful growth made clear that these design priorities no longer matched the needs of users in certain situations, particularly regarding accounting and resource management.

NSFNET usage grew dramatically, jumping from 85 million packets in January 1988 to 37 billion packets in September 1993. By 1992, the volume of traffic on NSFNET was approaching capacity, and NSF realized it did not have the resources to keep pace with the increasing usage. Consequently, the members of the consortium formed a private, non-profit organization called Advanced Networks and Services (“ANS”) to build a new backbone with transmission lines having thirty times more capacity. For the first time, a private organization &mdash; not the government &mdash; principally owned the transmission lines and computers of a backbone. At the time that privately owned networks started appearing, general commercial activity on the NSFNET was still prohibited by an acceptable use policy. Thus, the expanding number of privately owned networks were effectively precluded from exchanging commercial data traffic with each other using the NSFNET backbone. Several commercial backbone operators circumvented this limitation in 1991, when they established the Commercial Internet Exchange (“CIX”) to interconnect their own backbones and exchange traffic directly. Recognizing that the Internet was outpacing its ability to manage it, NSF decided in 1993 to leave the management of the backbone to the competing commercial backbone operators.

Federal support for the NSFNET backbone ended on April 30, 1995. At this time, the expanding network of commercial backbones permanently replaced NSFNET, effectively privatizing the Internet.

The growth of the Internet has been fueled in large part by the popularity of the World Wide Web, created in 1989. The number of websites on the Internet grew from one in 1989, to 18,000 in 1995, to fifty million in 2004, and to more than one hundred million in 2006. This incredible growth has been due to several factors, including the realization by businesses that they could use the Internet for commercial purposes, the decreasing cost and increasing power of personal computers, the diminishing complexity of creating websites, and the expanding use of the Web for personal and social purposes.

From its creation to its early commercialization, most computer users connected to the Internet using a “narrowband” dial-up telephone connection and a special modem to transmit data over the telephone system’s traditional copper wires, typically at a rate of up to 56 kilobits per second (“Kbps”). Much faster “broadband” connections have subsequently been deployed using a variety of technologies. These faster technologies include coaxial cable, upgraded copper digital subscriber lines, fiber-optic cables, and wireless, satellite, and broadband over power line (BPL) technologies.

The thousands of individual networks that make up the global Internet are owned and administered by a variety of organizations, such as private companies, universities, research labs, government agencies, and municipalities. Data packets may potentially travel from their originating computer server across dozens of networks and through dozens of routers before they reach an Internet service provider and arrive at a destination computer. This process of disassembly, transmission, and reassembly of data packets may take as little as a fraction of a second for a simple piece of information like a text e-mail traveling along a high-speed network, or it may take several hours for a larger piece of information like a high-resolution video traveling a long distance along a low-speed network.

Internet Architecture
The Internet is often described as being comprised of multiple “layers” including: a physical layer consisting of the hardware infrastructure used to link computers to each other; a logical layer of protocols, such as TCP/IP, that control the routing of data packets; an applications layer consisting of the various programs and functions run by end users, such as a Web browser that enables Web-based e-mail; and a content layer, such as a Web page or streaming video transmission.

The layers, are increasingly complex and specific components that are superimposed on but independent from other components. The technical protocols that form the foundation of the Internet are open and flexible, so that virtually any form of network can connect to and share data with other networks through the Internet. As a result, the services provided through the Internet (such as the World Wide Web) are decoupled from the underlying infrastructure to a much greater extent than with other media. Moreover, new services (such as Internet telephony) can be introduced without necessitating changes in transmission protocols, or in the thousands of routers spread throughout the network.

The architecture of the Internet also breaks down traditional geographic notions, such as the discrete locations of senders and receivers. The Internet]uses a connectionless, "adaptive" routing system, which means that a dedicated end-to-end channel need not be established for each communication. Instead, traffic is split into "packets" that are routed dynamically between multiple points based on the most efficient route at any given moment. Many different communications can share the same physical facilities simultaneously. In addition, any "host" computer connected directly to the Internet can communicate with any other host.

Today's Internet
Today, the Internet connects millions of individuals and organizations in a way that allows almost instantaneous communications using computers, computerized mobile devices, and other network attachments. End users interact with each other through an ever-expanding universe of content and applications, such as: e-mail, instant messaging, chat rooms, commercial websites for purchasing goods and services, social networking sites, Web logs (“blogs”), music and video downloads, political forums, voice over IP (“VoIP”) telephony services, streaming video applications, and multi-player network video games. Internet users include individuals of virtually all ages and walks of life, established businesses, fledgling entrepreneurs, non-profit groups, academic and government institutions, and political organizations.

Individual end users (and networks of end users arrange for Internet access via a “last mile” connection to an Internet service provider (“ISP”), which provides, in turn, routing and connections from the ISP’s own network to the Internet. Content and applications providers offer their products and services to end users via network operators, which enable connectivity and transport into the middle, or “core,” of the Internet.

Before the turn of the century, most computer users connected to the Internet using “narrowband,” dial-up telephone connections and modems to transmit data over the telephone system’s traditional copper wirelines. Much faster “broadband” connections recently have been deployed using various technologies, including coaxial cable wirelines, upgraded copper digital subscriber lines (“DSL”), and to a lesser extent fiber-optic wirelines, wireless, satellite, and broadband over power line (“BPL”) systems.

Traditionally, data traffic has traversed the Internet on a “first-in-first-out” ("FIFO") and “best-efforts” basis. This protocol for data transmission was established principally as a result of DARPA’s original priority, which was to develop an effective technique for communications among existing interconnected networks, and which placed network survivability &mdash; or the potential for robust network operation in the face of disruption or infrastructure destruction &mdash; as the top goal in designing the overall architecture of this network of networks.

Since the Internet’s earliest days, however, computer scientists have recognized that network resources are scarce and that traffic congestion can lead to reduced performance. Although different data transmission protocols and the viability of usage-based pricing mechanisms were explored throughout the 1980s and 1990s, the debate over broadband connectivity policy did not reach critical mass until recently.