The internet


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About the Internet for the classes III to VIII

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The internet

  1. 1. The Internet Chapter 3
  2. 2. Introduction <ul><li>Internet Stands for ‘ International Network’. </li></ul><ul><li>It is also known as ‘ Network of Networks’ . </li></ul><ul><li>It connects LANs, MANs, WAN and standalone PCs. </li></ul><ul><li>In the recent years, the term ‘ information superhighway ’ has also been applied to the Internet. </li></ul>
  3. 3. Characteristics of Internet <ul><li>It has no central controlling computer or device, although there are supercomputers that from the backbone of the Net. </li></ul><ul><li>There is no limit to the number of users that can be added to it. </li></ul><ul><li>It has no geographical limitations. </li></ul>
  4. 4. Applications of Internet (Advantages) <ul><li>Search for information </li></ul><ul><li>On-line marketing, on-line banking, on-line learning </li></ul><ul><li>Promoting business. </li></ul><ul><li>Downloading information, pictures, music, movie etc. </li></ul><ul><li>E-mail, chat, video conferencing </li></ul><ul><li>News and advertisement. </li></ul>
  5. 5. Basic Requirements <ul><li>A multimedia PC with a special communication software Browser </li></ul><ul><ul><li>Ex.: Internet Explorer, Netscape Navigator, Opera </li></ul></ul><ul><li>A Modem </li></ul><ul><li>A Telephone line or ISDN line </li></ul><ul><li>An Internet account(TCP/IP) with Internet Service Provider (ISP). </li></ul>
  6. 6. Modem <ul><li>Stands for Modulator-Demodulator. </li></ul><ul><li>It is a device that converts digital signals into analog signals that can be transmitted over a telephone line. </li></ul><ul><li>The modem converts an analog signal received over a communication channel back into digital signal. </li></ul>
  7. 7. Browser <ul><li>Browser is an interactive software between the users and the internet. </li></ul><ul><li>It accepts request from the user and passes to the web-server and in turn it receives the information and displays it on the user’s computer. </li></ul><ul><li>Examples: Internet Explorer, Mosaic, Netscape Navigator, Opera etc. </li></ul>
  8. 8. Internet Service Providers (ISPs) <ul><li>These are the organizations that provide the users with an access to the Internet. </li></ul><ul><li>Examples: America Online (AOL), Videsh Sanchar Nigam Limited (VSNL) and Satyam Online etc. </li></ul>
  9. 9. Protocols <ul><li>As defined in the earlier chapter, a protocol is a pre-determined set of rules and procedures that must be followed by the computer connected to the internet. </li></ul><ul><li>Protocols are used to define – instructions for activating or terminating a transmission. </li></ul><ul><li>Some most popular protocols are: TCP/IP, HTTP, Gopher </li></ul>
  10. 10. 1. TCP/IP (Transmission Control Protocol / Internet Protocol) <ul><li>This is divided into 2 parts: TCP and IP . </li></ul><ul><li>TCP is responsible for transmitting data from node to node in a network. </li></ul><ul><li>IP checks whether the data is reaching the appropriate node to which it was directed to or not. </li></ul><ul><li>They both work together. </li></ul>
  11. 11. 2. HTTP (Hypertext Transfer Protocol) <ul><li>It monitors the transfer of hypertext over the internet. </li></ul><ul><li>Hypertext is the highlighted text that activates a link to another hypertext document or a file. Ex: Slide1 , Introduction , Characteristics of Internet etc. </li></ul><ul><li>Hypertext document is created using a special computer language called Hypertext Markup Language (HTML). It is known as Web Pages . </li></ul>
  12. 13. … HTTP (Hypertext Transfer Protocol) <ul><li>URL stands for Uniform Resource Locator , which means it is a uniform (same throughout the world) way to locate a resource (file or document) on the Internet. </li></ul><ul><li>The URL specifies the address of a file and every file on the Internet has a unique address. </li></ul><ul><li>Ex: , </li></ul><ul><li>Web software, such as your browser, use the URL to retrieve a file from the computer on which it resides. </li></ul>
  13. 14. 3. Gopher <ul><li>This protocol is designed in a series of hierarchical menus. </li></ul><ul><li>It is used to view or download, search and retrieve documents over the internet. </li></ul>
  14. 15. Search Engine <ul><li>A web search engine is designed to search for information on the World Wide Web . </li></ul><ul><li>The search results are generally presented in a list of results and are often called hits . </li></ul><ul><li>Some popular search engines are : Google, Lycos, Yahoo, Indiatimes etc. </li></ul>
  15. 16. World Wide Web (W W W) <ul><li>WWW was developed at CERN, the European Laboratory for Particle Physics at Geneva in the early 1990s. It helps to distribute information over the internet. </li></ul><ul><li>The Web Pages contains text, graphics, forms, animations, video and sounds with links. </li></ul><ul><li>To allow access to documents that are created using HTML or its successors. </li></ul>
  16. 17. How Data Travels on the Internet ? <ul><li>The PC is connected to the internet using a modem and a telephone / ISDN line. </li></ul><ul><li>A request is made by the PC . </li></ul><ul><li>Router is a device that connects the networks, inspects this request and determines the path for the transmission to the appropriate destination computer. </li></ul>
  17. 18. … How Data Travels on the Internet ? <ul><li>The data is broken into Packets by a set of protocols . </li></ul><ul><li>These Packets are monitored by the Repeaters, Hubs, Bridges and Gateways while they are travel through the network. </li></ul><ul><li>Repeaters amplify the data signals and help them to reach remote PCs. </li></ul>
  18. 19. … How Data Travels on the Internet ? <ul><li>Hubs links groups of network together thereby making it possible for all the terminals to communicate with each other. </li></ul>
  19. 20. … How Data Travels on the Internet ? <ul><li>Bridges link LANs together in a WAN or MAN so that data can be properly transmitted. </li></ul>
  20. 21. … How Data Travels on the Internet ? <ul><li>Gateways translate data between one type of network and another. </li></ul><ul><li>When the request finally reaches its destination, the packets are read by the PC to which they were addressed to. </li></ul>