L J Haravu

What are networks? What is the Internet and how does it work?What is the Worldwide Web (WWW)? How is it different from the Internet?What is needed to access the Web?Important Web conceptsContent and services on the Internet

Whether we know it or not, we all belong to one or more networks

Family – Friends – Professional – Bank – Telephone - TV - Hobby – Religious, etc., etc.,

Network paradigmsShare and exchange data, information and knowledgeShare, exchange resourcesCollaborate on common projects/interestsInform, entertain

Computer networks are the infrastructure of the Internet

A local area network or LANA collection of computers within a building or office so that they can inter-communicate/share data, information

Wide Area Network (WAN)Connect computers across a wide geographical area, e.g., between different branches of a company in different parts of the country

It is a Network of Networks. Millions of networks – LANs, WANs, individual devices using diverse telecom networks connect to each other.All the networks agree to use common rules to connect to each other. These rules are called protocols

Protocols are based on a worldwide agreement of how to represent/exchange/transmit information. TCP/IP (Transmission Control Protocol/Internet Protocol) is a suite of protocols fundamental to the WebInternet software of all kinds conforms to the TCP/IP

Let’s see a Video of how the Internet works

The Internet is the medium or container or carrierThe Worldwide Web (WWW or Web) has the content The Web provides the means to store, access, communicate, retrieve information stored in millions of networks all over the world in different languagesThe Web is therefore also known as the Information SuperhighwayThe Web is the intelligence behind the hardware of the Internet. The intelligence behind the Web is from human beingsIt is not only an information network but also a knowledge network

Depending on the need for speed of a connection (also called Bandwidth) the options are:

Dial-upSlowest. Must dial-up to a phone line to connectInternet and phone cannot be used simultaneously

DSL or Digital Subscriber LineFaster than Dial-up. Always on. Higher speeds of access. Telephone and Internet can be used simultaneously

Cable Uses the Cable TV connection. Can be as fast as DSL, but security can be a problem

Wireless

Server

ClientClient Client

The Smart Class Facility at AVK will also be run as a Client-Server Facility

All networks including the Web are based on an architecture of Servers and ClientsA Server is a special type of computer on the network that provides one or more services to clients computers on the networkA Client is also a computer which users have access to on the network. The Client seeks services from the Server and the Server provides the services.

File Server

Database Server

Email Server

Web Server

Internet

Remote Client

There are dedicated servers that are generally owned by a web service provider, e.g., AVKs web site is located on a web server in the US provided by a company called GoDaddyWeb Servers are up and running 24 x 7 x 365 days The Web Service Provider also called Hosting provider provides the space, the software and maintenance of the site, security of dataThere are different types of servers: file, database, application, e-mail, etc.

Every site belongs to a domain, e.g., the schools domain name is acharyavidyakula.org. The School pays to own this domain nameA page on the web site has an address called the URL (Universal Resource Locator)

e.g., the URL for the Schools web site is http://www.acharyavidyakula.org) Once you know the URL of web sites/pages, these can be accessed with software known as a web browser, e.g., Internet Explorer, Firefox

The fundamental constituent of the Web is a pagePages that you see on a site are represented using a language called HTML (hypertext markup language)An HTML page can have text, symbols, images, video in it, e.g., http://www.acharyavidyakula.org/web/homeNot all pages of a site are static. Some of them are created dynamically

The ProcessA client machine connects to the InternetOnce connected, it requests a web site/page by entering the URL in a browserThe request passes through a maze of routers, switches, cables, satellite, cell phone towers, etc., and until it reaches the Web server The Web Server which is always ‘listening’ to requests, receives the request. It knows the address from where the request was receivedThe Web Server returns the page requested to the client by its addressSoftware on the client computer displays the page

An important element of most web pages is hypertext. This is specially formatted text. The hypertext is meant to connect the user to another page in the same site or to a page in some other site. The link is called a hyperlink. Let’s see an exampleHyperlinks can link to text, images, videos on one or more web sites/pages Some web pages have forms that can be filledMany web pages have a search box, e.g., Google

The Web is undoubtedly a veritable mine or repository of information. The following are a few of the types of sites/content available:

Simple textual pagesPages with more than just textual contentDatabase sites on various subjectsEmail providers, e.g., gmail, yahoo, rediffmailSites of companies, banks, institutions, schools, governments, international organizations, universities, charitable organizations, etc., etc.Library sites, e.g., SDM-IMD, Mysore

Digital libraries, e.g., The Hathi Trust, Google BooksSearch engine sites, e.g., Google, Bing, YahooSellers, resellers of goods and services, e.g. Amazon, Ebay – these are interactive sitesTravel Services such as travel agents, airline and railway reservations, e.g., the reservation site for Indian RailwaysReference Materials such as Encyclopedia’s, dictionaries, directoriesLearning resources Courseware sites, e.g., MIT Open Courseware

Scholarly subject portals, e.g., University of CaliforniaTutorial Sites on different subjects, e.g., HealthBlogsWikis of different kinds

The best example of a WIKI is Wikipedia

Music sites to listen/download music, e.g., MusicIndiaonlinePhoto publishing/sharing/downloading sitesVideos/Movies publishing/sharing/downloading sites, e.g., YoutubeSocial networking sites, e.g., Facebook

Exchange electronic mail (E-mail) with friends and colleagues with accounts on the InternetPost information for others to access, and update it frequentlySearch many types of general and specialized databasesAccess and use many services online, e.g., railway

reservations, e-bankingAccess/exchange multimedia information: audio,

photographic images and video, andBe part of an online social network, e.g., Facebook, etc., etc.,As a source of Infotainment As a source of knowledge (experience exchange)

access diverse perspectives from around the world.

The Web is a bad influence on childrenPrevent children from using the InternetWorkers waste time during office hours with the InternetThe Web has made us stupid. We only copy and paste and feel very great about it.