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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
• 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!
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
ARPANetTransmitting the Message
• Messages divided into packets
• TCP/IP protocol– TCP – does the packeting and
reassembling of the message– IP – handles the addressing
ARPANetExpands 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
URLUniform Resource Locator
• Unique address of a web page or file on the Internet
• Case-sensitive
http://domain-name.top-level-domain/last-section
httphypertext transfer protocol
• Protocol – rules
• Communication using links
http://domain-name.top-level-domain/last-section
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
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
http://domain-name.top-level-domain/last-section
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– E-mail– 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
BrowserParts of the screen
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
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
BrowserMenus and Buttons
• Pull-down menu• Buttons
– Convenient shortcuts for commonly used functions
– Click button rather than locate command from pull-down menu
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
Plug-ins
• Software that increases the functionality of a browser– Audio-video– Image viewing
• Download from web sites• Install• Example
– Adobe Acrobat Reader– Shockwave
ProgrammingJava• 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 ControlsCapabilities 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 <Enter>
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)
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 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
• 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 RequestsSearch Engine Database
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
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
Search Tools
Directories• Yahoo!
• NetGuide
Metasearch Sites• MetaCrawler
• Dogpile
Search Engines• AltaVista
• Excite
• 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
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
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)
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
e-mailClient Software Functions
Retrieve
Create
Send
Store
Delete
Address book
Attach files
Filters
IRCInternet Relay Chat
Not Quite Perfect Yet
• Unregulated
• Useless web sites
• Misinformation and misstatements on web sites
• Concern over government censorship
Not Quite Perfect YetSocial Issues
• Behavior problems– Who is out there?– What are they doing?
• Netiquette– Suggestions for appropriate behavior– Example: TYPING IN CAPS is shouting
