The Internet is a computer network that was designed to interconnect other computer networks. Its origins lie in the ARPANET, an experimental network designed for the U.S. Department of Defense Advanced Research Projects Agency (ARPA) in 1969. The original ARPANET had some features that were unique in its day.
The first unique feature was that it supported peer to peer networking. In this system, each computer has the same rights and abilities as any other computer on the network. The commercial computer networks at that time were hierarchical, where some devices performed special control functions, and other devices had to wait for permission to transmit from the controller.
Another unique feature of ARPANET was that it was not designed with a particular application or set of applications in mind. The designers created a network whose uses were not fully specified. As a result, ARPANET was designed to be transparent to applications. This allowed new Internet applications to be developed by placing the necessary functions (usually computer software) in end user devices rather than in the network. Thus, new applications did not require changes to the network.
Yet another unique feature of ARPANET was that it allowed organizations to have operational control of their local networks while still allowing them to be interconnected. This made it possible for a computer at a Burger King restaurant to communicate with a computer at a McDonald's restaurant without forcing the management at either restaurant to give up local autonomy for the privilege of communicating with each other.
In the 1980s, ARPANET split into a military component and a civilian section. The civilian part became known as NSFnet, in acknowledgement of support from the National Science Foundation. Other developments in this decade included the development of local area networks (LANs), which pushed peer to peer networking closer to many end users, and the microcomputer, or personal computer, which made it possible for many people to have dedicated computer access. NSFnet was limited by its charter to educational and not-for-profit organizations. Although commercial firms began to see the advantages of NSFnet, they were not able to participate fully in this new age of communications until NSFnet was privatized in 1993.
The Internet has grown in leaps and bounds since privatization, fueled by the emergence of a new application, the World Wide Web, and the resources of the private sector.
The Internet has become a change agent in many areas of the economy. Examples of this include retail sales, business to business transactions, telephoneand video carriage, and music distribution. In fact, few industries have not been touched in a significant way by the Internet. Many industries have reorganized themselves as a direct result of the economic changes brought about by Internet-based application.
For the most part, computers on the Internet communicate via two communications protocols: the Transmission Control Protocol (TCP) and the Internet Protocol (IP). The role of finding a path through a complex network is left to IP. This is a "best effort" protocol, in that it does the best it can to deliver a packet to the desired destination, but makes no promises. Thus, if a portion of the network failed, IP would attempt to reroute around the failure if it could, but would not guarantee that all packets would survive intact. Many applications require stronger assurances than this, and that is the role of TCP. The TCP is a communications protocol that operates between two end devices, ensuring that the complete information that was transmitted arrives safely at the destination. If some of the information is lost by IP, TCP retransmits it until it is received correctly. Thus, the two protocols operate in tandem to provide a complete, reliable service to end users.
The Internet differs from telephone networks in that information is broken into packets, each of which is treated separately, much like a letter. The Internet allocates its resources to individual packets as needed. By contrast, the telephone network treats a telephone call as a stream of information,and allocates resources to that call (or stream of information) regardless of whether the users are speaking or are silent. In a packet network, resources are allocated only when there is information to transmit. This packet switching feature is commonly found in computer networks.
Physically, the Internet consists of special purpose computers called routers that are interconnected with each other. Routers are equivalent to switches in the telephone network, in that they decide what to do with a packet when it arrives from a neighboring router. This decision is aided by a routing table, which is used by the router to determine where the packet should be sent next. The routing tables are constructed by the routers themselves, which communicate with each other so that efficient paths through the network can be found for packets traveling between any pair of destinations, and so that congested or failed routers can be avoided.
Today, many users access the Internet through Internet Service Providers (ISPs). For a monthly fee, an ISP provides users with a way of accessing the Internet (usually via a dialup modem), an electronic mail address and mailbox, and, often, a page that can be viewed by World Wide Web browsers. These retail ISPs often interconnect with large, high capacity backbone ISPs, which provide the transport functions so that a packet from one user can reach any other user.
The Internet is a constantly changing resource. It has had a deep impact on industries and on the lives of many Americans. The collection of computer networks known as the Internet will probably continue to affect society in ways that we are still trying to understand.
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The first unique feature was that it supported peer to peer networking. In this system, each computer has the same rights and abilities as any other computer on the network. The commercial computer networks at that time were hierarchical, where some devices performed special control functions, and other devices had to wait for permission to transmit from the controller.
Another unique feature of ARPANET was that it was not designed with a particular application or set of applications in mind. The designers created a network whose uses were not fully specified. As a result, ARPANET was designed to be transparent to applications. This allowed new Internet applications to be developed by placing the necessary functions (usually computer software) in end user devices rather than in the network. Thus, new applications did not require changes to the network.
Yet another unique feature of ARPANET was that it allowed organizations to have operational control of their local networks while still allowing them to be interconnected. This made it possible for a computer at a Burger King restaurant to communicate with a computer at a McDonald's restaurant without forcing the management at either restaurant to give up local autonomy for the privilege of communicating with each other.
In the 1980s, ARPANET split into a military component and a civilian section. The civilian part became known as NSFnet, in acknowledgement of support from the National Science Foundation. Other developments in this decade included the development of local area networks (LANs), which pushed peer to peer networking closer to many end users, and the microcomputer, or personal computer, which made it possible for many people to have dedicated computer access. NSFnet was limited by its charter to educational and not-for-profit organizations. Although commercial firms began to see the advantages of NSFnet, they were not able to participate fully in this new age of communications until NSFnet was privatized in 1993.
The Internet has grown in leaps and bounds since privatization, fueled by the emergence of a new application, the World Wide Web, and the resources of the private sector.
The Internet has become a change agent in many areas of the economy. Examples of this include retail sales, business to business transactions, telephoneand video carriage, and music distribution. In fact, few industries have not been touched in a significant way by the Internet. Many industries have reorganized themselves as a direct result of the economic changes brought about by Internet-based application.
For the most part, computers on the Internet communicate via two communications protocols: the Transmission Control Protocol (TCP) and the Internet Protocol (IP). The role of finding a path through a complex network is left to IP. This is a "best effort" protocol, in that it does the best it can to deliver a packet to the desired destination, but makes no promises. Thus, if a portion of the network failed, IP would attempt to reroute around the failure if it could, but would not guarantee that all packets would survive intact. Many applications require stronger assurances than this, and that is the role of TCP. The TCP is a communications protocol that operates between two end devices, ensuring that the complete information that was transmitted arrives safely at the destination. If some of the information is lost by IP, TCP retransmits it until it is received correctly. Thus, the two protocols operate in tandem to provide a complete, reliable service to end users.
The Internet differs from telephone networks in that information is broken into packets, each of which is treated separately, much like a letter. The Internet allocates its resources to individual packets as needed. By contrast, the telephone network treats a telephone call as a stream of information,and allocates resources to that call (or stream of information) regardless of whether the users are speaking or are silent. In a packet network, resources are allocated only when there is information to transmit. This packet switching feature is commonly found in computer networks.
Physically, the Internet consists of special purpose computers called routers that are interconnected with each other. Routers are equivalent to switches in the telephone network, in that they decide what to do with a packet when it arrives from a neighboring router. This decision is aided by a routing table, which is used by the router to determine where the packet should be sent next. The routing tables are constructed by the routers themselves, which communicate with each other so that efficient paths through the network can be found for packets traveling between any pair of destinations, and so that congested or failed routers can be avoided.
Today, many users access the Internet through Internet Service Providers (ISPs). For a monthly fee, an ISP provides users with a way of accessing the Internet (usually via a dialup modem), an electronic mail address and mailbox, and, often, a page that can be viewed by World Wide Web browsers. These retail ISPs often interconnect with large, high capacity backbone ISPs, which provide the transport functions so that a packet from one user can reach any other user.
The Internet is a constantly changing resource. It has had a deep impact on industries and on the lives of many Americans. The collection of computer networks known as the Internet will probably continue to affect society in ways that we are still trying to understand.
SOURCE