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

• 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

• 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

• E-mail

• 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

Print

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