The Internet: A Resource for All of Us Chapter 6

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

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

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

ARPANet Advanced 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

ARPANet Transmitting the Message Messages divided into packets TCP/IP protocol –TCP – does the packeting and reassembling of the message –IP – handles the addressing

ARPANet Expands Beyond the Military Research computers from universities Defense contractors Needed technical expertise to work on Internet

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

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

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

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

URL Uniform Resource Locator Unique address of a web page or file on the Internet Case-sensitive

http hypertext transfer protocol Protocol – rules Communication using links

Domain name Address of the ISP Domain names are registered Ongoing fee is paid for each domain name

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

Last section Directories and file names that specify a particular web page

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

Internet Service Provider Vehicle to access the Internet Provides –Server computer –Software to connect

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

Wireless Internet Access Supports mobile handheld devices –Text pagers –PDAs –Pocket computers –Web-enabled cellular phones Applications – –Checking weather –Making airline reservations

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

Browser Netscape Communicator Microsoft Internet Explorer

Browser Used to explore the Internet Dials the ISP Display web pages

Browser Parts of the screen

Browser Functions 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

Browser Functions 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

Browser Menus and Buttons Pull-down menu Buttons –Convenient shortcuts for commonly used functions –Click button rather than locate command from pull-down menu

Browser Support Frames 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

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

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

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

Moving Between Sites Clickable categories in the browser –Sports –Weather –News –Technology –Comic strips Enter the URL in the address text box and press

Processing Requests URL 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)

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

Processing Requests Search 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

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 Processing Requests Search Engine Database

Processing Requests Directory 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

Processing Requests Search 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

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

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

Other Uses of the Internet Newsgroups FTP Telnet Internet Relay Chat (IRC)

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)

Newsgroup Operations Lurking Posting material –Inappropriate material Flame Flame war –Moderated newsgroup

FTP File 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

Public Archives Free files provided by educational institution or the government

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)

Send/receive written messages Most used feature of the Internet Mail server – Collects and stores Mailbox – Assigned to each user address –User name –Domain of the mail server

Client Software Functions Retrieve Create Send Store Print Delete Address book Attach files Filters

IRC Internet Relay Chat

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

Not Quite Perfect Yet Social Issues Behavior problems –Who is out there? –What are they doing? Netiquette –Suggestions for appropriate behavior –Example: TYPING IN CAPS is shouting