This document uses a number of terms with which you need to be familiar. They can be found in the Glossary found on page 13. We will start this section by answering this question, “What is the Internet? ” The Internet is a world-wide network of computers. It is an Information Superhighway that carries traffic to and from a collection of servers– remote computers that handle requests for data and information, much like the waiter in a restaurant that takes orders for food.
This collection of servers distributed all over the world and is called the World Wide Web (WWW). Servers respond to clients– computers that request information, much like a customer in a restaurant orders food from the waiter. You click links to text, pictures, music, or video located on these servers. In addition, you can play the selected files on your local client PC, workstation, or terminal, as well as, links to related information located on these servers.
Therefore, you do not have to remember where the information is located or to learn any obscure commands to access the Web. What are the Advantages of the Internet? Now that you know what theI internet is, you will learn about its advantages and how it is used to For computers to access the Internet, they require a physical means of transferring information software applications that retrieve and send information and allow users access information. There are three common methods of accessing the Internet:
Dial Up Modem: First, the most common method for individual computers to connect to the Internet is via dial up modem, which is used to provide a connection to an ISP– Internet Service Provider over normal telephone lines: Dedicated Line: Another method for computers to connect is through a dedicated line. Companies may use a dedicated communications link connection, such as an ISDN– telephone company land-lines or On Ramp– a utility to connect to an ISP or the main link (backbone) of the telecommunications carrier.
The dedicated line allows you to connect to an ISP or the main link (backbone) of their telecommunications carrier. Mobile: Mobile users can connect to the Internet through mobile phones or via satellite using a portable satellite transceiver. This section has provided an analysis of the physical means to transfer data. Now that we know the physical means to transfer data, the next section discusses the physical requirements for the Internet to work. What is Required for the Internet to Work? The following physical requirements are needed for the Internet to work:
Clients: Clients communicate with a WWW server using the Hypertext Transfer Protocol (HTTP). Thus, when you select a WWW link, the client looks up the hostname and makes a connection with the WWW server. Then the HTTP software on the server responds to the client’s request and the client and the server close the connection. Servers: For applications to work, there must be computers to provide e-mail and Web services. Servers run server applications that store and transmit e-mail messages, as well as distribute Web page content.
Other servers provide additional support services such as identification of computers by name, e-commerce payment gateways (which process credit card payments) and proxy servers (which allow your ISP to provide faster Web browsing services). Since every Internet application requires a server somewhere to provide these services, still other servers run multi-play games, store and distribute news, provide chat and ICQ facilities and distribute music. Routers: In addition to servers to run applications, routers are needed to direct information.
Routers are dedicated computers that interconnect the various parts of the Internet. When a router receives a packet– a package of data exchanged between devices over a data communication link– of information it reads the header. This determines where the information came from and where it needs to go. If the packet needs to go to a computer on the same network, the router simply ignores it. On the other hand, if the packet needs to go to a computer on a different network, the packet is passed on to the destination network.
At the destination network, the destination router performs a similar function. It ignores packets destined for its network and passes packets on to other networks as appropriate. Packets: The Internet transfers data around the network in discrete packets of information. Since there are now millions of computers on the Internet, it is impossible to have physical circuits connecting each computer to the others. Thus, it is impossible to use switched circuits since the delay in establishing and disconnecting switched circuits each time a connection was made would effectively stop the Internet.