Network, Internet and Network, Internet and World Wide WebWorld Wide Web

Essential Concepts Essential Concepts

Natalia Mosina - 2005 Natalia Mosina - 2005

NetworkNetwork

• Most people work in a network environment

A network is a collection of computers connected together with special hardware and software to manage it.

LAN – local area network (small area)

WAN – wide area network (long distances)

From LAN to WAN

(a) Home Network

(b) Local Area Network

From LAN to WAN (continued)

(c) Wide Area Network

The InternetThe Internet

A network of networks,A network of networks,

interconnected collection of interconnected collection of networksnetworks

Began in 1960s as Began in 1960s as government (military) project government (military) project

It is a hardware!It is a hardware!

Consists of computers Consists of computers and the communications and the communications links that connect themlinks that connect them

The World Wide WebThe World Wide Web

Began in 1991 at the European Particle Began in 1991 at the European Particle Physics Laboratory (CERN) in Switzerland Physics Laboratory (CERN) in Switzerland

It is a software!It is a software! Consists of different files, documents, and Consists of different files, documents, and

software that stores and retrieves those software that stores and retrieves those files.files.

Web is a collection of files that reside on Web is a collection of files that reside on Web Servers that are located all over the Web Servers that are located all over the world.world.

Client vs. ServerClient vs. Server

When you connect to Internet to become When you connect to Internet to become part of the web, your computer becomes a part of the web, your computer becomes a Web client in a worldwide client/server Web client in a worldwide client/server network.network.

Web browser is the software that you run Web browser is the software that you run on your computer to make it work as a on your computer to make it work as a Web client.Web client.

A Client/Server ModelA Client/Server Model

A A serverserver (Web server or Web site) is any (Web server or Web site) is any computer that stores documents and furnishes computer that stores documents and furnishes them upon request them upon request

AA client client is any computer that requests services is any computer that requests services (requests and then displays documents )(requests and then displays documents )

Every client must be able to display every Every client must be able to display every document from every server and does so document from every server and does so through a browser (e.g., Netscape or Internet through a browser (e.g., Netscape or Internet Explorer) Explorer)

Acronyms Acronyms

HTTPHTTP – HyperText Transfer Protocol is – HyperText Transfer Protocol is used to transmit Web documents used to transmit Web documents

HTMLHTML – HyperText Markup Language is – HyperText Markup Language is the language for all Web documents the language for all Web documents

ISISP P – Internet service provider – Internet service provider IP - IP - Internet protocolInternet protocol TCPTCP - Transmission Control protocol - Transmission Control protocol DNSDNS – Domain Name System – Domain Name System

Connecting to the InternetConnecting to the Internet

At Work or School At Work or School Via a Local Area Network Via a Local Area Network

At Home At Home Traditional Modem (56Kbps) Traditional Modem (56Kbps) Cable Modem Cable Modem

Uses TV cable Uses TV cable Requires network card Requires network card

DSL Modem DSL Modem Voice and data on the same line Voice and data on the same line Requires network card Requires network card

Uniform Resource Locator (URL)Uniform Resource Locator (URL)

http://www.prenhall.com/reed/index.htmlhttp://www.prenhall.com/reed/index.html

Protocol (means of access)

Web Server

Directory where the Page is stored

Name of the page Or document

URL URL

Top-level domains include “edu,” “gov,” and Top-level domains include “edu,” “gov,” and “org,” but “com” is most common “org,” but “com” is most common

Examples: Examples: www.microsoft.comwww.microsoft.com www.nba.comwww.nba.com www.whitehouse.govwww.whitehouse.gov www.miami.eduwww.miami.edu

E-Mail (Electronic Mail)E-Mail (Electronic Mail)

E-mail is simply a means of sending E-mail is simply a means of sending messages via computer messages via computer

Business is using more e-mail and fax Business is using more e-mail and fax To access, you must have a mail server To access, you must have a mail server

and/or software and/or software Each person has a username and pass-word Each person has a username and pass-word All mail programs allow you to Send, All mail programs allow you to Send,

Compose, Reply, and Forward Compose, Reply, and Forward

An E-mail AddressAn E-mail Address

Every e-mail address is unique and consists Every e-mail address is unique and consists of two parts, a user name and a host of two parts, a user name and a host computer: computer: johndoe@anyschool.edujohndoe@anyschool.edu

The@ sign is required The@ sign is required The host computer can be omitted if you are The host computer can be omitted if you are

logged onto the same network or host logged onto the same network or host computer computer