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The Internet: A Resource for All of Us

The Internet: A Resource for All of Us. Chapter 8. Objectives. Briefly describe the history of the Internet Explain what is needed to get on the Internet Describe generally what an Internet service provider does Describe the rudimentary functions of a browser

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The Internet: A Resource for All of Us

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  1. The Internet:A Resource for All of Us Chapter 8

  2. Objectives • Briefly describe the history of the Internet • Explain what is needed to get on the Internet • Describe generally what an Internet service provider does • Describe the rudimentary functions of a browser • Describe how to search the Internet • List and describe the non-Web parts of the Internet • Explain some of the ongoing problems associated with the Internet

  3. Contents • History of the Internet • URL • Getting Started • Internet Service Provider • Browser • Browser Support • Moving Between Sites • Searching the Internet • Other Uses of the Internet • Internet Issues

  4. History of the Internet • Government and Universities over 30 years • Who’s connected today? • Individuals • Educational institutions • Government • Research • Medical • Businesses • Everyone!

  5. ARPANetAdvanced Research Projects Agency Network • 1969 – US Department of Defense and Rand Corporation • Origins • Cold War – fear that a bomb could demolish computing capabilities • Several computers, geographically dispersed, networked together • Plan – if one computer was disabled, others could carry on using alternative communication routes

  6. ARPANetTransmitting the Message • Messages divided into packets • TCP/IP protocol • TCP – does the packeting and reassembling of the message • IP – handles the addressing

  7. ARPANetExpands Beyond the Military • Research computers from universities • Defense contractors • Needed technical expertise to work on Internet

  8. Tim Berners-Lee • 1990 • Perceived a spider’s web of computers with links from computer to computer • CERN site • Dr. Berners-Lee’s physics laboratory • Birthplace of the World Wide Web • Easy movement due to links • Hypertext • Hyper-region

  9. Marc Andreessen • 1993 • Created browser software • Mosaic – first browser • Provided attractive images and a graphical interface permitting users to click on pictures as well as text

  10. ARPANet to Internet • TCP/IP software is public domain • Network became more valuable as it embraced other networks • ARPANet disappears

  11. Internet Explosion • Mid 1990s • Estimate over 333 million users worldwide • Part of our daily lives • Four factors • TCP/IP standard • Ability to link from site to site • Ease of use of browser • Growth of PC and LANs that can connect

  12. URLUniform Resource Locator • Unique address of a web page or file on the Internet • Case-sensitive http://domain-name.top-level-domain/last-section

  13. httphypertext transfer protocol • Protocol – rules • Communication using links http://domain-name.top-level-domain/last-section

  14. Domain name • Address of the ISP • Domain names are registered • Ongoing fee is paid for each domain name http://domain-name.top-level-domain/last-section

  15. Top-level Domain Represent the purpose of the organization of entity .com .gov .edu .org .net May be a two-letter country code

  16. Last section Directories and file names that specify a particular web page http://domain-name.top-level-domain/last-section

  17. Getting Started • Computer with a modem or NIC • Internet service provider (ISP) • Browser • Related software

  18. Internet Service Provider • Vehicle to access the Internet • Provides • Server computer • Software to connect

  19. Online service • ISP • Members-only services and information • Simple interface with clickable topics • Parent controls

  20. Wireless Internet Access • Supports mobile handheld devices • Text pagers • PDAs • Pocket computers • Web-enabled cellular phones • Applications • E-mail • Checking weather • Making airline reservations

  21. Wireless Internet Access • Need • Account with wireless access provider • Cellular modem card or adapter • Wireless Application Protocol (WAP) • Convert web pages into format for mobile devices • Resized for limited display area • Fewer graphics transmitted • Slow download speeds

  22. Browser Netscape Communicator Microsoft Internet Explorer

  23. Browser • Used to explore the Internet • Dials the ISP • Display web pages

  24. BrowserParts of the screen

  25. BrowserFunctions and Features • Browser display window • Displays contents of web page from each Internet site visited • Screen limits how much of the site you can view at a time. The page can be scrolled using the scroll bar to see its entire contents • Status line – progress of data being transferred and other messages

  26. BrowserFunctions and Features • Welcome banner on title bar • Browser logo – animation indicates you are in the process of moving to a new site • Hot list • Bookmark • Favorites • Store your favorite URLs • Browser control panel – menus and buttons

  27. BrowserMenus and Buttons • Pull-down menu • Buttons • Convenient shortcuts for commonly used functions • Click button rather than locate command from pull-down menu

  28. Browser SupportFrames • Divides page into rectangular sections • Each section displays web pages independently • Several small pages on one screen • Can be scrolled independently • Can be replaced with other pages independently

  29. Plug-ins • Software that increases the functionality of a browser • Audio-video • Image viewing • Download from web sites • Install • Example • Adobe Acrobat Reader • Shockwave

  30. Programming Java • Write software that is machine independent • Programming language • Dancing icons • Sound clips • Flashing messages • Banners that scroll • Applets – Permits dynamic web pages • Display animations • Receive input • Perform calculations

  31. Programming ActiveX Controls Capabilities similar to Java Browser must be enabled to support applets / ActiveX Controls Security issues

  32. Moving Between Sites • Clickable categories in the browser • Sports • Weather • News • Technology • Comic strips • Enter the URL in the address text box and press <Enter>

  33. Processing RequestsURL • User enters a URL • User computer sends request to the ISP server • ISP server sends request across networks of TCP/IP computers • Destination site is reached • Content is transmitted back to your computer (process in reverse)

  34. Searching the Internet Search engine • User specifies a search request • Browser links to Search Engine • Request returns matching pages based upon the Search Engine’s database • Results presented

  35. Processing RequestsSearch Engine Database • Search Engine builds database • Searchable terms • Related web sites • Spider, robot, bot • Follows links across the web • Automatically indexes pages to a database • One word • All words • Pages may be submitted by the owner

  36. Processing RequestsSearch Engine Database • Request same search using different engines yields different results • Databases built independently • Size • Content • Search methodology • Metasearch – atomically puts the same request to several search engines

  37. Processing RequestsDirectory vs. Search Engine • Directory • Human involvement • Sites organized by content category • May concentrate on specific content areas • Subjective decisions regarding inclusion and importance • Search Engine • Spider, robot, or bot automatically builds database • Index on a few keywords • Index on all words on web page

  38. Processing RequestsSearch Engine Limitations • Index only a fraction of the Web • Approximately 20% to 33% of sites • More web pages added daily • Solution • Same request to several search engines • Metasearch

  39. Directories Yahoo! NetGuide Metasearch Sites MetaCrawler Dogpile Search Engines AltaVista Excite Google HotBot Infoseek Lycos Northern Light Search Tools

  40. Refine the Search • Add words • Enclose words in “quotes” • Use Boolean logic • Examples • “World Trade Center” • Jordan AND NOT Michael

  41. Other Uses of the Internet • Newsgroups • FTP • Telnet • E-mail • Internet Relay Chat (IRC)

  42. Newsgroups / Usenet • Large bulletin board divided by category • Posting and reading of messages that focus on specific topics • Over 20,000 newsgroups • Functions • Conversation • File download • Newsreader software required (included with most browsers)

  43. Newsgroup Operations • Lurking • Posting material • Inappropriate material • Flame • Flame war • Moderated newsgroup

  44. FTPFile Transfer Protocol • Download files to your local computer • Upload files to another computer • Requirements to download file • Permission to download from a site • File is available for copying • Anonymous FTP – do not need to identify yourself to the remote computer

  45. Public Archives Sounds Free files provided by educational institution or the government Images Graphics Programs Text

  46. Telnet • Use your PC as a terminal providing remote access to another computer • Permits • Log on to a host • Use as if you are sitting at a local terminal • Need account on the host system • Telnet software required (provided with most browsers)

  47. e-mail • Send/receive written messages • Most used feature of the Internet • Mail server – Collects and stores e-mail • Mailbox – Assigned to each user • E-mail address • User name • @ • Domain of the mail server

  48. Retrieve Create Send Store Print Delete Address book Attach files Filters e-mailClient Software Functions

  49. IRCInternet Relay Chat

  50. Not Quite Perfect Yet • Unregulated • Useless web sites • Misinformation and misstatements on web sites • Concern over government censorship

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