ch 2 the internet and pp presentations... · 2009. 9. 1. · lan ( local area network): is a...

The Internet and WWWThe Internet and WWWObjectives:Objectives:

•• Networks LAN/WAN.Networks LAN/WAN.

•• Internet.Internet.

•• How the Internet worksHow the Internet works

•• Explain what the World Wide Web is and Explain what the World Wide Web is and

how it works.how it works.

•• Identify the elements of a Web browser Identify the elements of a Web browser

and explain how the browser works.and explain how the browser works.

•• Tell what determines how fast a Web page Tell what determines how fast a Web page

loads.loads.

•• Create a simple Web document.Create a simple Web document.

Network:Network:A A computer networkcomputer network is a system for is a system for

communicationcommunication among two or more among two or more

computerscomputers. .

LANLAN ( ( local area network):local area network): is a is a computer networkcomputer networkcovering a local area over short distances , like a covering a local area over short distances , like a home, office or small group of buildings such as a home, office or small group of buildings such as a

college using cables and hardwarecollege using cables and hardware installed on installed on

each computereach computer. . LANs can be interlinked by LANs can be interlinked by connections to form a Wide area network. A connections to form a Wide area network. A routerrouteris used to make the connection between LANs.is used to make the connection between LANs.

WAN (wide area network):WAN (wide area network): Is a computer Is a computer

network that connects many computers over network that connects many computers over

large distances, using transmission lines large distances, using transmission lines

similar to those used in telephone systems.similar to those used in telephone systems.

Each networking technology moved information Each networking technology moved information

around in a different way, often based on the around in a different way, often based on the

design of its hardware. A particular LAN technology design of its hardware. A particular LAN technology

could only work with specific computers, and most could only work with specific computers, and most

LAN and WAN technologies were incompatible with LAN and WAN technologies were incompatible with

each other.each other.

What is the Internet?What is the Internet?

•• It is a computer network that connects It is a computer network that connects

millions of computers globally and millions of computers globally and

provides worldwide communication to provides worldwide communication to

businesses, homes, and governments.businesses, homes, and governments.

How the Internet began?

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�� In a network a In a network a Host NodeHost Node, or , or HostHost, is , is

any computer that directly connects any computer that directly connects

to the network. A host often stores to the network. A host often stores

and transfers data and messages on and transfers data and messages on

high speed communication lines and high speed communication lines and

provides network connections for provides network connections for

other computers.other computers.

Internet ServicesInternet Services

�� World Wide WebWorld Wide Web

�� Electronic mail (eElectronic mail (e--mail)mail)

�� File TransferFile Transfer

�� NewsgroupsNewsgroups

�� Message boardsMessage boards

�� Mailing ListMailing List

�� Chat RoomsChat Rooms

�� Instant MessagingInstant Messaging

Connecting to the InternetConnecting to the Internet

�� SlowSlow--speed technology:speed technology:

DialDial--up access.up access.

�� HigherHigher--speed Internet connections: speed Internet connections:

DSL (Digital Subscriber Line),DSL (Digital Subscriber Line),

cable modem, cable modem,

fixed wireless, fixed wireless,

satellite modem.satellite modem.

Access Access ProvidersProvidersISP (Internet ISP (Internet ServiceService ProviderProvider):): isis a a businessbusiness thatthat has a has a permanentpermanentInternet Internet connectionconnection andand providesprovidestemporarytemporary connectionsconnections toto individualsindividualsandand companiescompanies forfor free free oror forfor a a feefee..

Regional ISPRegional ISP: : UsuallyUsually providesprovides accessaccess toto thetheInternet Internet throughthrough oneone oror more more telephonetelephonenumbersnumbers local local toto anan specificspecific geographicalgeographicalareaarea..

NationalNational ISPISP: : LargeLarge businessbusiness thatthat providesprovideslocal local telephonetelephone numbersnumbers in in mostmost majormajor citiescitiestowntown nationwidenationwide. . ExamplesExamples EarthlinkEarthlink, , AT&TAT&T, , WorldComWorldCom..

OSP (Online Service Provider):OSP (Online Service Provider):

Supplies Internet access but also has Supplies Internet access but also has

many membersmany members--only features that only features that

offer a variety of special content and offer a variety of special content and

services such as: news, weather, services such as: news, weather,

legal information, financial data, legal information, financial data,

hardware and software guides, hardware and software guides,

games and travel guides. Examples. games and travel guides. Examples.

AOL, MSN.AOL, MSN.

WSP (Wireless Service Provider):WSP (Wireless Service Provider):

Is a company that provides wireless Internet Is a company that provides wireless Internet

access to users with wireless modems or access to users with wireless modems or

WebWeb--enabled handheld computers or enabled handheld computers or

devices. Examples, AT&T Wireless, devices. Examples, AT&T Wireless,

GoAmericaGoAmerica, T, T--Mobile, and Mobile, and VerizonVerizon WirelessWireless

Computers connected to the Internet work Computers connected to the Internet work together to transfer data and information together to transfer data and information around the world using around the world using SERVERS AND SERVERS AND CLIENTSCLIENTS..

TCP/IPTCP/IP: It is the software used on the : It is the software used on the Internet to pass information from machine Internet to pass information from machine to machine and from network to network. to machine and from network to network. It contains two components Internet It contains two components Internet Protocol (IP) and Transmission Control Protocol (IP) and Transmission Control Protocol (TCP)Protocol (TCP)

�� When connected to the When connected to the Internet, all you have to Internet, all you have to do is key in the Web do is key in the Web address (address (URL, Uniform URL, Uniform Resource LocatorResource Locator) and ) and your your Web BrowserWeb Browser (the (the program you use to program you use to access the Web) contact access the Web) contact the computer where that the computer where that page is stored (the page is stored (the Web Web serverserver).).

The server receives your The server receives your message and sends the message and sends the page by breaking the page by breaking the information up into little information up into little bundles called bundles called packetspackets..

Each packet has your computer’s address on them Each packet has your computer’s address on them and are looking traveling the Internet looking for and are looking traveling the Internet looking for your computer. If a packet get lost, your your computer. If a packet get lost, your browser will tell the server to send it again. As all browser will tell the server to send it again. As all the packets begin to reach your browser, it the packets begin to reach your browser, it assembles them into a Web page and displays assembles them into a Web page and displays the page to you.the page to you.

Other network computers ( Other network computers ( routers routers ) help send the ) help send the packets on to their destinations and help locate packets on to their destinations and help locate other routes when one becomes broken or other routes when one becomes broken or clogged with traffic.clogged with traffic.

A A Web browserWeb browser is the software that you use to is the software that you use to retrieve and view Web pages. It allows you to retrieve and view Web pages. It allows you to follow hyperlinks to see new documents.follow hyperlinks to see new documents.

How data might travel using a How data might travel using a

Telephone line connectionTelephone line connection

IP AddressIP Address:: short for internet short for internet

protocol address, is a number that protocol address, is a number that

uniquely identifies each computer or uniquely identifies each computer or

devise connected to the Internet.devise connected to the Internet.

•• Consist s of 4 groups of numbers, each Consist s of 4 groups of numbers, each

( from 0 to 255) separated by a period . ( from 0 to 255) separated by a period .

(199.95.72.10).(199.95.72.10).

•• The first portion of each IP address The first portion of each IP address

identifies the network and the last identifies the network and the last

portion identifies the specific computerportion identifies the specific computer

�� Typically, a Typically, a URLURL follows this format and follows this format and contains components named the contains components named the following ways: following ways:

protocolprotocol://://computer.domain.name/computer.domain.name/pathnamepathname//filename.extfilename.ext or or

typeoftransfertypeoftransfer://servername.domain/://servername.domain/directory.subdirectorydirectory.subdirectory//filenamefilename..filetypefiletype

Protocol, domain name, and path to a specific Web Protocol, domain name, and path to a specific Web page or location on a Web.page or location on a Web.

Most Web page URLs begin with http:/. The Most Web page URLs begin with http:/. The httphttpstands for stands for hypertexhypertex transfer protocoltransfer protocol, which is , which is the communications standard that enables pages the communications standard that enables pages to transfer on the Web.to transfer on the Web.

Domain name:Domain name: is the text version of an is the text version of an IP address.IP address.

�� Every domain name contains a Every domain name contains a toptop--level domain (TLD)level domain (TLD) abbreviation that abbreviation that identifies the type of organization that identifies the type of organization that is associated with the domain.is associated with the domain.

�� The group that assigns and controls The group that assigns and controls TLDsTLDs is the is the Internet Corporation for Internet Corporation for Assigned Names and NumbersAssigned Names and Numbers(ICANN)(ICANN)

Common ProtocolsCommon Protocols

HowHow

Domain NamesDomain Names

WhereWhere

Top Level Domain TLDTop Level Domain TLD

Cont. Top Level Domain TLDCont. Top Level Domain TLD

PathPath

Who/WhatWho/What

What is a World Wide Web?What is a World Wide Web?

The most popular internet service. It consists of The most popular internet service. It consists of a worldwide collection of electronic documents. a worldwide collection of electronic documents. Each of these electronic documents on the Web Each of these electronic documents on the Web is called a Web page.is called a Web page.

1.1. Easy to use.Easy to use.

2.2. It is interactive and combines It is interactive and combines

graphics, text, sound, and graphics, text, sound, and

animation.animation.

3.3. It is easy to create the files that It is easy to create the files that

become a Web site. become a Web site.

Why it is so popular?Why it is so popular?

SummarySummary

How Does the Web Work?How Does the Web Work?

�� Computers request Computers request

information from information from

servers:servers:

•• BrowsersBrowsers on on

computerscomputers use use URLsURLs

((www.disney.comwww.disney.com) to ) to

locate Web pages on locate Web pages on

ServersServers..

•• RoutersRouters locate the locate the

requesting computers requesting computers

and Web servers.and Web servers.

�� Packets:Packets:

•• ServersServers break break

information into information into

little bundles called little bundles called

packets. packets.

•• RoutersRouters send send

packets to their packets to their

destination.destination.

•• If packets get lost, If packets get lost,

they are requested they are requested

and sent again.and sent again.

Your Connection to the WebYour Connection to the Web

�� Web browser:Web browser:

•• Puts packets back Puts packets back

together.together.

•• Interprets HTML Interprets HTML

tags on Web tags on Web

pages and pages and

displays Web displays Web

content.content.


�� Web browser Web browser

displays:displays:

•• Search tools.Search tools.

•• Hyperlinks to Hyperlinks to

proceed to pages.proceed to pages.

•• Back button to Back button to

return from pages.return from pages.


�� Web browser’s Web browser’s parts:parts:•• Navigation buttonsNavigation buttons

•• Address boxAddress box

•• Status iconStatus icon

•• Content areaContent area

•• Status barStatus bar

�� Enter URLs:Enter URLs:•• www.course.comwww.course.com

•• www.geocities.cowww.geocities.comm

•• www.altavista.comwww.altavista.com


�� Web indexes and Web indexes and

search tools:search tools:

•• Yahoo!Yahoo!

•• AltaVistaAltaVista

•• GoogleGoogle

�� Enter URLs:Enter URLs:

•• www.yahoo.comwww.yahoo.com


•• www.google.comwww.google.com

An index organizes pages by topics.

Search tools search by keywords.

How Fast Is the Web?How Fast Is the Web?

Text browsers don’t.

GUI browsers show

pictures.


�� Web speed is Web speed is

determined by: determined by:

•• Size of Web page.Size of Web page.

•• User’s connection User’s connection

speed.speed.

•• Internet Traffic.Internet Traffic.

•• Server’s Server’s

connection speed.connection speed.

•• Web server speed.Web server speed.


�� Graphics take Graphics take

longer to load.longer to load.

�� Text pages load Text pages load

faster.faster.

Making a Simple Web PageMaking a Simple Web Page

�� Web pages are Web pages are

made up of tags: made up of tags:

•• Opening or Opening or

starting tagsstarting tags

•• Angle bracketsAngle brackets

•• Information to be Information to be

displayed in displayed in

content areacontent area

•• Closing tagsClosing tags

Hello, my name is Hello, my name is

____.____.



____.____.

�� These tags will These tags will

create this Web create this Web

page.page.

SummarySummary

In this lesson, you learned:In this lesson, you learned:

�� What the World Wide Web is and how it What the World Wide Web is and how it

works.works.

�� To identify the elements of a Web browser To identify the elements of a Web browser


�� To determine how fast a Web page loads.To determine how fast a Web page loads.

�� To create a simple Web document.To create a simple Web document.

The Internet and WWWThe Internet and WWWObjectives:Objectives:

•• Networks LAN/WAN.Networks LAN/WAN.

•• Internet.Internet.

•• How the Internet worksHow the Internet works

•• Explain what the World Wide Web is and Explain what the World Wide Web is and

how it works.how it works.

•• Identify the elements of a Web browser Identify the elements of a Web browser


•• Tell what determines how fast a Web page Tell what determines how fast a Web page

loads.loads.

•• Create a simple Web document.Create a simple Web document.