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The Internet and World Wide Web

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What You Will Learn . . .

How the Internet worksMethods for accessing the InternetThe Internet and the World Wide Web

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HypertextWeb browsers and Web servers

What You Will Learn . . .

Parts of a URLHow to access Web pagesWeb subject guides and search engines

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Use operators to improve search resultsReliability of information on the WebMost popular Internet services

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The Internet

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The Internet is a global, interconnected computerThe Internet is a global, interconnected computernetwork in which every computer connected to it can network in which every computer connected to it can exchange data with any other connected computerexchange data with any other connected computer

How the Internet Works

Interoperability is the ability to communicate with a computer even if it is a different brand or model

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Accessing the Internet and Web

You will need:A i h i h Wi d

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A computer with an operating system, such as Windows,MAC OS, or UNIX, that supports Internet protocolsCommunications equipment such as a modem, ISDN adapter, or Ethernet cardAn Internet service provider (ISP)Web browser software such as Internet Explorer or Netscape Navigator

Accessing the Internet

The Internet can be accessed in the following ways:Dial-up access with Point-to-Point Protocol (PPP)Digital Subscriber Line (DSL)Cable and satellite accessLAN

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LAN access

Internet historyhttp://www.zakon.org/robert/internet/timeline/

The Internet and Web: What’s the Difference?

The Internet is the physical connection of millions of networksThe Web uses the Internet for its existenceTh W b i t f h t t b dd d W b

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The Web consists of hypertext embedded on Webpages that are hosted on Web sites

The Web Site

A Web site is a collection of related Web documents that are made available to the publicThe index page, or home

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p g ,page, is the first page of a Web siteWeb pages are individual Web documents

The Hypertext ConceptHypertext is a way of presenting information so that the order in which it’s read is left up to the reader

Hyperlinks are underlined or highlighted words that can be used to view another document or Web page

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Hypermedia refers to a link to multimedia, such as music and movies

The Web is a distributed hypermedia system or a system where the responsibility for creating content is distributed among many people

Web Browsers and Servers

Web browsers display a Web document and enable

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p yusers to link to other Web pages

The first browsers were text-onlyMosaic was the first graphical browser (April 1993)

Web servers respond to the requests of browsers. They find and send requested resources back to the browser

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Mosaic

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June 1993 Ver.: 0.1a

Nov 1993 Ver.: 1.0

Oct 1995 Ver.: 2.0

Web addresses are an addressing system that identifies where a Web resource is locatedThe uniform resource locator (URL) is the standard used to identify Web resourcesThe URL consists of:

Web Addresses (URLs)

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URL http://

Protocolidentifies the means of access

www.yahoo.com/

Server contains the domain name of the Web server

help/shop/

Path identifies the

location of the document

shop-01.html

Resourcespecifies the

filename of the resource

Browsing the Web

To access a Web page, you can do any of the following:

Click a hyperlinkType a URL in the Address box

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Click a button on the Links toolbarUse the Back and Forward buttonsUse a Web site’s navigation aidsUse the History listUse the Favorites or Bookmarks list

Standard Toolbar–Contains Navigation buttons

Address Bar–Contains URL of Web page

Back & Forward Buttons–Take you to recently visited pages

Stop Button–Stops downloading

Refresh Button–Updates (refreshes) the pageHome Button– Returns to default start page

Search Button– Opens search engine program

Favorites Button– List of bookmarked Web pages

Media Button– Opens media player program

History Button– List of Web sites visited over a period of time

E-Mail Button– Opens e-mail program

Printer Button– Prints documents

Other Navigation ButtonsProgram icon–Animates when downloading

The Web Browser’s WindowClick to view the various parts of a Web browser’s window.

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Status bar– Messages about the browser’s operation

Hyperlinks

IP Address

Internet Protocol (communications standard) A unique id no. (just like your postal address)Typical IP address: 216.27.61.137IP is assigned by network administratorYou can check your IP (Windows)

“run” → “cmd” → “ipconfig”

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Domain Names

Names are easy to remember than IP addresseshttp://hk.yahoo.com = 202.43.220.99

In Windows, “run” → “cmd”→ “nslookup”

You can own your domain namesYou can own your domain namesFor .com, .net, .org, .us…etc.

e.g. www.networksolution.com

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Uploading and DownloadingDownloading – document or file is transferred from another computer to your computerUploading – files transferred

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p gfrom your computer to another computer

Emerging TechnologiesWays to share information on the Internet

Wiki – open-content encyclopediaWeblog (blog) – Internet journal or diaryMoblog (mobile blog) - content posted from a portable phone or PDA

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Finding Information on the Web

Ways to find information on the Web:

Browse or surf the Web – This involves linking from one Web page to another, and so forth

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page o a o e , a d so oSearch the Web – This method involves using search engines to locate Web pages with the information you’re looking forSubject guides – Web pages are grouped under headings

Using Search Engines

To use a search engine, you:Choose a search engine (MSN, Lycos, Alta-Vista, Yahoo, etc)Type in one or more words describing your topic

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The search engine checks its database of Web pages that contain the words typedThe results are sent to your computerClicking on the link takes you to that page

Using Search Techniques

Learning a few search techniques can increase the accuracy of Web searchesSearches using search operators will improve search performanceM h i h f ll i h

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Most search engines use the following search operators:

Inclusion/exclusion operatorsWild cardsPhrasesBoolean operators

The following tables show the results of using and not using search operators

Words Entered

Possible Results –Web pages containingFire

Words Entered Possible Results – Web pages containing

+Fire+station Fire station

+Fire+station* Fire stationFire stations

No Search Operators

Using Search Operators

Using Search Techniques

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Fire station stationFire station

+Fire-station* Fire

“Fire station” Fire station

Fire and station Fire station

Fire or stationFire stationFire station

Fire not station Fire

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Rules for Evaluating Web Pages

1. Author – Who is the author?2. Sources – Where does the information come from?3. Server – Who provides the server for the page?4. Objectivity – Is the information objective or one-

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sided?5. Style – Is the language objective or argumentative?6. Purpose – What is the purpose of the page?7. Accuracy – Is the information accurate?8. Currency – Is the page up-to-date?

Using the Web for Schoolwork

Use authoritative online sourcesUse your library to find articles and booksCite online and offline references

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E-Mail: Staying in Touch

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E-mail is short for electronic mailIt’s the most popular of the Internet servicesMessages are sent and received in a few secondsAttachments such as photos, music files, and any document may be sent with the message

E-Mail Addresses

myname@someserver.comUsers name@name of the server that the user is on

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Spam: Can It Be Stopped?

Spam – unsolicited e-mail advertising

With Spam the recipient pays the postage

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To avoid spamAvoid posting your e-mail addressUse spam protectorsDon’t reply to spam

Instant Messaging: E-Mailing Made Faster

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Instant messaging systems let a user know when a friend or business associate is onlineIt provides a means of communicating through real-time, text-based conversations

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IRC: Text Chatting in Real Time

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Internet relay chat consists of real-time, text-based conversationsChat groups are divided into channels that cover a specific topic

Your Computer FTP Server

DOWNLOAD

UPLOAD

File Transfer Protocol (FTP)

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FTP is a part of the Internet that enables client computers to transfer filesTransferring files from an FTP site to the client is known as downloadingTransferring files from the client to an FTP site is known as uploadingClients may store files on an FTP site’s server

Usenet

Usenet is the part of the Internet which enables users to participate in discussions and newsgroupsUsenet newsgroups are

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Usenet newsgroups are organized into hierarchies (categories) and subcategoriesSubcategories include Standard, Alt, Biz, and Local newsgroups

Standard Newsgroup Subcategories

comp computer applications, databases, multimedia

misc activism, books, business, health

sci chemistry, archeology, math

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soc human rights, world cultures

talk Euthanasia, gun control, religion

news Usenet announcements

rec sports, gardening, bicycles

Listservs: Electronic Mail Lists

A listserv is an automatic list serverMail is sent to everyone on the list when e-mail is

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generated.It is similar to a newsgroup or a forum

Summary

• The Internet is the network of networks• The Internet is accessed by way of an ISP• World Wide Web is a global system with

billions of hypertext document• Related information is linked using hypertext

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g yp• A Web browser is a program that displays Web

pages• URL consists of a protocol, a server, a path, and

a resource name• Search engines enable you to search huge

databases of Web documents

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Summary (continued)

• You can improve search results using operators

• You should always evaluate information you receive from the Web

• Popular Internet services

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• E-mail• Instant messaging• Internet Relay Chat• File Transfer Protocol• Discussion groups• Listservs

Wired and Wireless Communication

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What You Will Learn . . .

The definition of bandwidthThe bandwidth needs of a typical userHow modems change digital signals into analog Transmission media and methods

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Limitations of public switched telephone network (PTSN) for sending and receiving data

What You Will Learn . . .

Multiplexing and digital telephony and their impact on line usageExamples of how digitization and convergence are blurring the boundaries between popular

i i d i

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communication devicesVarious wired and wireless applications

Connectivity

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the ability to link various media and devices

Moving Data: Bandwidth and ModemsCommunications – sending and receiving messagesCommunications channels – paths through which messages are passedSignals can be:

Analog – data is in continuous waveforms

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gDigital – data is in discontinuous pulses (0’s & 1’s)

digital

analog

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Moving Data: Bandwidth and ModemsBandwidth – the amount of data that can be transmitted through a given communications channel

Analog measured in cycles per second (Hz)Digital measured in bits per second (bps)

Broadband – any transmission medium that transports

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high volumes of data at high speeds

Moving Data: Bandwidth and ModemsModems

Transmit data over telephone linesModulation – converts digital (from computer) to analog to cross telephone linesDemodulation – converts analog (phone lines) to digital for

t

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computer

Wireless Transmission Media

Wireless transmission media refers to the methods of carrying data through the air or space using infrared, radio, or microwave signals

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Wireless Transmission Media: Twisted Pair

Twisted Pair – two insulated wires twisted

around each other –used for telephone

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pwires

Wireless Transmission Media: Coaxial Cable

Coaxial Cable – center copper wire surrounded by insulation, surrounding a layer of braded wire

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Wireless Transmission Media: Fiber Optic

Fiber-optic cable – thin strands of glass that carry data by light pulses

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Wireless Transmission Media: Infrared

Infrared is a wireless transmission medium that carries data via light beams

Transmitter and receiver must be in line of sightAn IrDa port is needed to use infrared with a computer

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Wireless Transmission Media: RadioRadio is a wireless transmission medium that carries data via radio frequency signals

Wireless LANs in a home or business are one type of radio technologyRadio signals can be long range (between cities or regions)

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and short range (within a building)Radio signals are susceptible to noise and electrical interference

Wireless Transmission Media: Bluetooth

Short-range radio transmission technology

Devices identify each other by identification numberConnection is confirmed

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Connection is confirmed before it is made finalDoes not require a line of sight

Wireless Transmission Media: Microwaves

Microwaves are high-frequency radio waves

Much of long-distance telephone service is carried by

i

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microwavesMicrowaves travel in a straight lineMicrowave relay stations are built about 30 miles apart

Wireless Transmission Media: Satellites

Satellites are microwave relay stations suspended in space

They are positioned in geosynchronous orbits

Satellites use microwave signals to transmit data to d f th b d i l t ti

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and from earth-based microwave relay stations

Wired Communication via the PSTNThe public switched telephone network (PSTN) is the world telephone system

It is used for data as well as voice communicationsTwisted-pair wire and fiber-optic cable provide the connections for the systemHome and business phones are connected to subscriber

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ploop carriers (SLCs)The area serviced by SLCs is called the local loop

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Multiplexing

Multiplexing technology enables simultaneous multi-use of transmission lines

Copper wire allows up to 24 simultaneous calls per wire

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Fiber-optic cable permits up to 43,384 calls per strand

Last Mile TechnologiesThe “last mile” refers to the phone lines that connect homes and businesses to the local loop

The inability of users to access the high-speed fiber-optic cable creates a bottleneck of data called the last mile problem

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Last Mile TechnologiesDigital telephony technologies that use twisted-pair wire are referred to as last mile technologies

ISDNDSLCable Modems

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Leased linesSONETMMDS

Convergence: Is it a Phone or a Computer?

Digitization – transformation of data into digital formConvergence – merging of disparate objects or ideas i t e bi ti

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into new combinations

Cellular Telephones

Cellular telephones enable calls to be placed through a wireless telecommunications system

Cellular phones use radio or infrared signals

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Cellular phones use radio or infrared signalsCells are limited geographic transmission

areasA mobile telephone switching office(MTSO) monitors the signal strength of cellular phones

Risk of Using Cell Phones????

Frequency (Hertz, Hz)

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Power (Watt, W)

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Personal Communication Service (PCS)

Personal Communication Service (PCS) refers to digital cellular telephone service technologiesDigital cellular phones offer:

N i f d

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Noise-free soundImproved coverageProtection from eavesdropping and phone fraudVoice recognitionHigh-speed Internet access

Web-Enabled Devices

A Web-enabled device is any device that can display and respond to HTML or XMLPDAs, cell phones, and tablet PCs are Web-enabled devices

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Wired and Wireless Applications

Internet telephone – using the Internet for real-time voice communications

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Wired and Wireless Applications

Videoconferencing – using sound and video technologies to meet with others

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Facsimile (Fax) Transmission

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Fax transmission is the means of sending an image of a document over telephone lines

Fax modems support fax as well as data protocols

Satellite Radio, GPS

Satellite radio - broadcasts are transmitted through a satellite

GPS – global positioning systems27 earth orbiting satellites

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Navigation systems

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Text, Picture, and Video Messaging

Text messaging – sending text communications over a cell phone

Picture messaging – using h t d i t

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camera phones to send pictures to other cell phones

Summary

• Bandwidth is the data transfer capacity of a communication channel

• A modem is used to send digital data over a phone line

• Physical and wireless media are used to

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ycommunicate with technology

• The public switched telephone network (PSTN) is mostly digital

Summary

• Multiplexing is the transmission of more than one communication on a single line

• Digitization is the transformation of data into digital form

• Internet telephony and faxing can be

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p y gaccomplished through the Internet