The Internet, also called the Net, is an international network that connects many thousands of networks and millions of computers across the world. Used by many people and organizations to communicate and share information, the Internet links computers of different sizes and types.
To be able to communicate with each other and exchange information, these different types of computers need to comply with a set of standard communication rules called protocol. All computers connected to the Internet use IP, Internet Protocol, which controls the break up of data messages into units called packets, and governs the routing of data from sender to receiver.
IP is one of a suite of protocols known as Transmission Control Protocol/Internet Protocol, or TCP/IP, which was developed by the US Department of Defense to enable communications over different types of networks.
To connect to the Internet, you need Internet access. For home computer users, this is usually accomplished by dialing up an Internet Service Provider (ISP) via a modem. Another way to gain Internet access is through a dedicated line (such as a T1 carrier), connected to a local area network (LAN). A dedicated line is usually used by a large organization or company, which either has its own node on the Internet or is connected to an ISP.
The backbone of the Internet consists of high-speed data communication lines linking major nodes or host computers. These lines carry the bulk of the data traffic. Major Internet service providers (ISPs) own the largest networks, which comprise the backbone of the Internet. By connecting together, these networks form an extremely fast data pipeline that crisscrosses the world.
No one can cause the Internet to crash, as no single computer or node controls it. One or more Internet nodes could fail without jeopardizing the Internet as a whole or preventing communications. However, different parts of the world are not equally well defended against Internet service failure. In more developed countries, the backbone of the Internet usually has redundant intersecting points. If one part fails, data traffic is quickly rerouted to another. This feature is called Redundancy. The more redundancy the backbone has, the more reliable the Internet service is.
To connect to the Internet, you need Internet access. For home computer users, this is usually accomplished by dialing up an Internet Service Provider (ISP) via a modem. Another way to gain Internet access is through a dedicated line (such as a T1 carrier), connected to a local area network (LAN). A dedicated line is usually used by a large organization or company, which either has its own node on the Internet or is connected to an ISP.
The backbone of the Internet consists of high-speed data communication lines linking major nodes or host computers. These lines carry the bulk of the data traffic. Major Internet service providers (ISPs) own the largest networks, which comprise the backbone of the Internet. By connecting together, these networks form an extremely fast data pipeline that crisscrosses the world.
No one can cause the Internet to crash, as no single computer or node controls it. One or more Internet nodes could fail without jeopardizing the Internet as a whole or preventing communications. However, different parts of the world are not equally well defended against Internet service failure. In more developed countries, the backbone of the Internet usually has redundant intersecting points. If one part fails, data traffic is quickly rerouted to another. This feature is called Redundancy. The more redundancy the backbone has, the more reliable the Internet service is.
The earliest model of the Internet was created with extreme reliability in mind. The start of the Internet was a decentralised network called ARPANET (Advanced Research Projects Agency Network) created in 1969 by the US Department of Defense to provide a communications network capable of surviving a nuclear attack. Eventually, other networks, such as Usenet, BITNET, and NSFnet (created by US National Science Foundation) were connected to ARPANET.
To deliver Internet services, many technologies such as fiber optics, cable television wires and satellites have been used. Virtual libraries and museums, games, E-business, and online monetary transactions are some of the many applications being developed and driven by the Internet.
The original services
The services that were used in the Internet immediately after its inception were primarily intended to make use of the greater possibilities made available by a network as opposed to stand-alone computers: resource-sharing and the exchange of messages. Three original application protocols developed were e-mail, file transfer and remote logon.
The services that were used in the Internet immediately after its inception were primarily intended to make use of the greater possibilities made available by a network as opposed to stand-alone computers: resource-sharing and the exchange of messages. Three original application protocols developed were e-mail, file transfer and remote logon.
1. Electronic mail
Electronic mail, or e-mail, is one of the original applications of the Internet. It is based on the simple mail transfer protocol (SMTP) and the post office protocol (POP) and is used for the transmission of short text messages between two users. E-mail is certainly one of today's major Internet teleservices.
Electronic mail, or e-mail, is one of the original applications of the Internet. It is based on the simple mail transfer protocol (SMTP) and the post office protocol (POP) and is used for the transmission of short text messages between two users. E-mail is certainly one of today's major Internet teleservices.
2. File transfer
The purpose of the file transfer application is to provide a number of users with the possibility of sharing common storage resources from which files can be retrieved when required - with or without some form of authorisation control (for example, user name and password). Transfer is normally performed using the file transfer protocol (FTP).
Retrieving files from different file archives is a popular service. Some file archives function as anonymous FTP servers, meaning that no special authorisation is required to gain access to the material stored there.
The purpose of the file transfer application is to provide a number of users with the possibility of sharing common storage resources from which files can be retrieved when required - with or without some form of authorisation control (for example, user name and password). Transfer is normally performed using the file transfer protocol (FTP).
Retrieving files from different file archives is a popular service. Some file archives function as anonymous FTP servers, meaning that no special authorisation is required to gain access to the material stored there.
3. Remote logon
Remote logon enables users to connect to other computers and use their resources. This service originated at a time when computers and processing power were in short supply but in great demand. The protocol for the service is called TELNET.
Remote logon enables users to connect to other computers and use their resources. This service originated at a time when computers and processing power were in short supply but in great demand. The protocol for the service is called TELNET.
Other Services on the Internet include the following:
1. Discussion groups
The Internet has not only made worldwide data communication possible but has also made it simple and inexpensive. The most common communication service is e-mail, but the Internet can also be used as a meeting place where users can "congregate" and discuss issues of common interest.
The Internet has not only made worldwide data communication possible but has also made it simple and inexpensive. The most common communication service is e-mail, but the Internet can also be used as a meeting place where users can "congregate" and discuss issues of common interest.
2. News groups
Internet news groups are forums for debate and exchange of information on different subjects. There is a wide variety of subjects ranging from cooking to programming; however, technology-oriented subjects (in particular those related to computer science) dominate. The news-group service can be described as e-mail addressed to an impersonal party - a subject field.
Internet news groups are forums for debate and exchange of information on different subjects. There is a wide variety of subjects ranging from cooking to programming; however, technology-oriented subjects (in particular those related to computer science) dominate. The news-group service can be described as e-mail addressed to an impersonal party - a subject field.
Discussion groups are not based on real-time communication. Instead, users submit their articles or questions after which a response may be entered by other members of the group. The various questions and answers are saved in a catalogued structure so that they can be read at a time convenient for the reader. The advantage of this arrangement is that users have access to topics discussed earlier, although it is somewhat difficult to maintain a concise overview of the structure.
The network news transfer protocol (NNTP) is used for the transfer of information to and from discussion-group members.
3. Chat
Chat is a sort of discussion forum in which members converse - via a text-based interface - over a network of interconnected servers. Numerous users can communicate with one another at the same time. A channel is created when the first user connects and ceases to exist when the last user terminates communication. A message that is written by one user and then sent over the channel is immediately distributed to all other users connected to that channel. Unlike news, chat is based on real-time communication.
Chat is a sort of discussion forum in which members converse - via a text-based interface - over a network of interconnected servers. Numerous users can communicate with one another at the same time. A channel is created when the first user connects and ceases to exist when the last user terminates communication. A message that is written by one user and then sent over the channel is immediately distributed to all other users connected to that channel. Unlike news, chat is based on real-time communication.
The protocol that connects the servers with one another, and the individual clients with their respective servers, is called the Internet relay chat (IRC) protocol.
4. Information retrieval
Information retrieval over the Internet has almost become synonymous with the World Wide Web (WWW). The Web represented an enormous breakthrough for the Internet and is probably the application that has been most instrumental in the rapid spread of the Internet around the world. Ironically, the Web is also responsible for a good portion of the criticism that has been aimed at the Internet. There is an enormous amount of information making it more or less impossible to maintain a simplified overview, and dramatic increases in Internet traffic have also led to lengthy response times.
Information retrieval over the Internet has almost become synonymous with the World Wide Web (WWW). The Web represented an enormous breakthrough for the Internet and is probably the application that has been most instrumental in the rapid spread of the Internet around the world. Ironically, the Web is also responsible for a good portion of the criticism that has been aimed at the Internet. There is an enormous amount of information making it more or less impossible to maintain a simplified overview, and dramatic increases in Internet traffic have also led to lengthy response times.
Information retrieval is greatly facilitated by the use of search engines (such as Alta Vista or Yahoo!), which help locate the desired type of information by browsing through millions of pages in hundreds of thousands of servers. A search engine can search on titles, uniform resource locators (URLs), key words and phrases.
5. Commerce
Commerce over the Internet represents one of the most interesting application areas for future Internet services. One idea is for the Internet to be used as a sort of gigantic, continuously updated mail-order catalogue containing products and services. The physical delivery of ordered software and information will be performed directly over the Internet. The international features of the Internet will make it suitable as a tool for commerce across national borders, with the ensuing problems relating to customs and value-added tax collection.
Commerce over the Internet represents one of the most interesting application areas for future Internet services. One idea is for the Internet to be used as a sort of gigantic, continuously updated mail-order catalogue containing products and services. The physical delivery of ordered software and information will be performed directly over the Internet. The international features of the Internet will make it suitable as a tool for commerce across national borders, with the ensuing problems relating to customs and value-added tax collection.
6. Telephony
Telephony over the Internet is a more recent service. An important advantage of this service is the low price. Users only pay for the connection set-up to their Internet service supplier - usually the price of a local call - and can then call other users anywhere in the world. The disadvantage is that the Internet, as a packet-switched network, is not designed for the transfer of services that are sensitive to delays and delay variations, in particular. Delays can become significantly large (in the range of seconds) and can also vary with time. Moreover, no common standard exists. This means that parties wishing to carry on telephone conversations over the Internet must install the special telephony software from the same service provider.
Telephony over the Internet is a more recent service. An important advantage of this service is the low price. Users only pay for the connection set-up to their Internet service supplier - usually the price of a local call - and can then call other users anywhere in the world. The disadvantage is that the Internet, as a packet-switched network, is not designed for the transfer of services that are sensitive to delays and delay variations, in particular. Delays can become significantly large (in the range of seconds) and can also vary with time. Moreover, no common standard exists. This means that parties wishing to carry on telephone conversations over the Internet must install the special telephony software from the same service provider.
7. Multimedia services
a. Multimedia
Multimedia is a term often used in connection with the Internet. It can be described as a service that employs at least two of the three service types voice, data and video and also entails a certain degree of interactivity. The term "voice" can be expanded to include audio in general. Data traffic is currently the primary traffic type transmitted over the Internet, but the transmission of sound and video is increasing. A reasonable prediction is that the Internet will be carrying large volumes of multimedia traffic in the near future.
Multimedia is a term often used in connection with the Internet. It can be described as a service that employs at least two of the three service types voice, data and video and also entails a certain degree of interactivity. The term "voice" can be expanded to include audio in general. Data traffic is currently the primary traffic type transmitted over the Internet, but the transmission of sound and video is increasing. A reasonable prediction is that the Internet will be carrying large volumes of multimedia traffic in the near future.
b. Videoconferencing
High-quality videoconferencing requires at least six times the bandwidth of ordinary telephony. It works best if run over an intranet since these networks offer approximately 10 times greater bandwidth than the Internet.
High-quality videoconferencing requires at least six times the bandwidth of ordinary telephony. It works best if run over an intranet since these networks offer approximately 10 times greater bandwidth than the Internet.
c. Video transmission
Multicast backbone (Mbone) and streaming video are used when transmitting video over the Internet. Mbone is a logical, broadband network that is superimposed on the ordinary Internet network. It consists of a number of servers that support multicast, that is, one sender and several receivers. Although some Internet routers do not "understand" IP multicast, they can be used for Mbone traffic if the traffic is encapsulated in normal TCP packets by means of special Mbone computers.
Multicast backbone (Mbone) and streaming video are used when transmitting video over the Internet. Mbone is a logical, broadband network that is superimposed on the ordinary Internet network. It consists of a number of servers that support multicast, that is, one sender and several receivers. Although some Internet routers do not "understand" IP multicast, they can be used for Mbone traffic if the traffic is encapsulated in normal TCP packets by means of special Mbone computers.
The streaming video technique employs a high degree of video information compression and display of information at the receivers' concurrent with the transfer of subsequent information. The flow is smoothed by a buffer in the receiving equipment.
8. Business services
Companies have a number of alternatives when employing the Internet or Internet technologies in their internal networks.
a. Intranets
An intranet is a company network based on the use of Internet technology. The prime advantage of an intranet is a possibility provided by WWW techniques: having a common interface for different information formats. Information can be disseminated quickly and in a uniform manner. Employees can use the same software that they use when retrieving information directly from Internet sources. An intranet can be used to retrieve information from databases, to distribute company news or for special Web pages that serve as bulletin boards. An intranet is ordinarily protected by a firewall to prevent intrusion (unauthorised access). An extranet is a solution whereby a company offers certain external individuals (customers and subcontractors) limited access to the information available on the company's intranet.
An intranet is a company network based on the use of Internet technology. The prime advantage of an intranet is a possibility provided by WWW techniques: having a common interface for different information formats. Information can be disseminated quickly and in a uniform manner. Employees can use the same software that they use when retrieving information directly from Internet sources. An intranet can be used to retrieve information from databases, to distribute company news or for special Web pages that serve as bulletin boards. An intranet is ordinarily protected by a firewall to prevent intrusion (unauthorised access). An extranet is a solution whereby a company offers certain external individuals (customers and subcontractors) limited access to the information available on the company's intranet.
b. Virtual private networks
A company can interconnect local data networks to form a virtual private network (VPN) by using the Internet. The service is offered by Internet operators in the form of a "public intranet", a term which in itself is a contradiction. Internet operators can provide better quality of service (QoS) via a public intranet than in the public Internet.
A company can interconnect local data networks to form a virtual private network (VPN) by using the Internet. The service is offered by Internet operators in the form of a "public intranet", a term which in itself is a contradiction. Internet operators can provide better quality of service (QoS) via a public intranet than in the public Internet.
Internet Development Organisations
Many organizations and institutions contribute their computing resources to maintain and update various parts of the Net. The Internet is indisputably a collaborative, joint entity. No one person, governmental or non-governmental organization can claim ownership or control of the Internet.
Many organizations and institutions contribute their computing resources to maintain and update various parts of the Net. The Internet is indisputably a collaborative, joint entity. No one person, governmental or non-governmental organization can claim ownership or control of the Internet.
On the other hand, IT industry leaders exert their influence through setting standards that the various hardware and software systems should comply with. Also, many governments have begun to legislate the Internet.
Among the organizations that play significant roles in the development of the Internet are:
• ISOC (Internet Society): ISOC is a professional membership society made up of many entities of the Internet Economy (individuals, government agencies, corporations, foundations, and non-profit organizations). The group comments on Internet policies and practices. Overseeing IAB and IESG, ISOC promotes the use, development and maintenance of the Internet. It is a free-standing organisation with headquarters in Reston, Virginia, in the US.
• ISOC (Internet Society): ISOC is a professional membership society made up of many entities of the Internet Economy (individuals, government agencies, corporations, foundations, and non-profit organizations). The group comments on Internet policies and practices. Overseeing IAB and IESG, ISOC promotes the use, development and maintenance of the Internet. It is a free-standing organisation with headquarters in Reston, Virginia, in the US.
The objectives of the ISOC are:
• to maintain and develop Internet standards;
• to develop effective administrative processes for the operation of the Internet;
• to expand and develop Internet architecture; and
• to promote the development of and accessibility to the Internet.
• to maintain and develop Internet standards;
• to develop effective administrative processes for the operation of the Internet;
• to expand and develop Internet architecture; and
• to promote the development of and accessibility to the Internet.
ISOC membership has grown steadily since the organisation was formed in 1992. Today, members include government agencies, other non-profit organisations, private corporations and private individuals. (www.isoc.org)
• IETF (Internet Engineering Task Force): IETF is a large open international community of network designers, which focuses on the development of the Internet, and proposes solutions to technical problems related to the Internet. The IETF's most important function is to assign priorities to the various protocols that are to be developed and integrated into the Internet protocol suite. The IETF started as a forum for the coordination of technical matters that concerned the various suppliers to the ARPA 1986 project. The association has since then grown into an open, international organisation of network designers, network operators, manufacturers and researchers all involved in the development of the Internet. (www.ietf.org)
The IETF's objectives are:
• to identify and suggest solutions to technical operational problems arising in the Internet;
• to specify the development and use of protocols and architecture;
• to be a forum for the exchange of information between manufacturers, users, researchers and network operators.
• to identify and suggest solutions to technical operational problems arising in the Internet;
• to specify the development and use of protocols and architecture;
• to be a forum for the exchange of information between manufacturers, users, researchers and network operators.
All technical work is carried out in working groups, each being responsible for a particular area - for example, applications, network management and security. Each of the areas has an area director. The IETF nominates future members of the IESG and the IAB.
• IESG (Internet Engineering Steering Group): IESG is a group that manages IETF activities, and reviews standards proposed by IEFT. IESG is responsible for the technical control of the Internet Engineering Task Force's (IETF's) work and administers the Internet standardisation process in accordance with a set of established rules. IESG consists of the IETF's area directors and the IETF's chairman, who is also chairman of the IESG. (http://www.ietf.org/iesg.html)
• W3C (World Wide Web Consortium): W3C is a body encouraging the development of open Web standards such as HTML (Hypertext Markup Language). The World Wide Web Consortium (W3C) promotes the use of the World Wide Web by developing specifications and products. Different member companies finance W3C operations. However, the products that are developed are free of charge and can be used freely by anyone. (www.w3.org)
• IAB (Internet Architecture Board): IAB is a technical advisory group that provides guidance to the IETF, and defines the overall architecture of the Internet and its backbone. Formerly the Internet Activities Board, the Internet Architecture Board (IAB) consists of 13 members, each of whom has one vote. IAB members are not appointed on the basis of any specialist competence but rather because of their broad overall knowledge of the Internet. Issues addressed by the IAB often deal with future strategies and international cooperation. The objective is results that can be used as guidelines by the IESG. The IAB, which is a technical reference group affiliated with the ISOC, publishes Internet Official Standards on a quarterly basis. (www.iab.org)
• IANA (Internet Assigned Numbers Agency): Protocol specifications contain parameters (such as port numbers and error codes) that must be uniquely defined. The IAB is responsible for this undertaking but delegates the task to the Internet Assigned Numbers Agency (IANA), which publishes the defined parameters in a periodic RFC under the title Assigned Numbers. (www.iana.org)
• IRSG (Internet Research Steering Group): The Internet Research Steering Group (IRSG) functions as the decision-making group for the Internet Research Task Force (IRTF). It has the same relationship to IREF as that existing between the IESG and the IETF. (www.irsg.org)
• IRTF (Internet Research Task Force): The IRTF, which does not directly participate in the standardisation process, investigates subjects that are considered too uncertain, advanced or insufficiently scrutinised to be included in the standardisation process. The IRTF's efforts may then lead to specifications of sufficient maturity to become a standard. (www.irtf.org)
• IRSG (Internet Research Steering Group): The Internet Research Steering Group (IRSG) functions as the decision-making group for the Internet Research Task Force (IRTF). It has the same relationship to IREF as that existing between the IESG and the IETF. (www.irsg.org)
• IRTF (Internet Research Task Force): The IRTF, which does not directly participate in the standardisation process, investigates subjects that are considered too uncertain, advanced or insufficiently scrutinised to be included in the standardisation process. The IRTF's efforts may then lead to specifications of sufficient maturity to become a standard. (www.irtf.org)
• ICANN (The Internet Corporation for Assigned Names and Numbers): ICANN is a non-profit corporation responsible for administering IP addresses and domain names. (www.icann.org)
• InterNIC (Internet Network Information Center): InterNIC is an organization responsible for assigning domain names. (www.internic.net)
