The Internet: A Resource for All of Us - PowerPoint PPT Presentation

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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