Internet and WWW

By:- Sagar Rai PII Msc Computer Science

St Philomena PG Centre, Puttur

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History of Internet1972 Telnet developed as a way to connect

to remote computer

1973 Email introduced, ARPANET goes international and File Transfer Protocol (FTP) established.

1984 Domain Name Server introduced which allows naming of hosts, no longer numeric

1986 NSFNET created

1991 Tim Berners-Lee releases World Wide Web

1993 Mosaic (becomes Netscape) designed by graduate students at University of Illinois

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The Internet Internet is an massive network of networks. It is essentially an interconnection between millions of smaller computer networks scattered around the globe. These networks are connected with each other by the means of over ground cables, underground cables, satellite links and sub-oceanic cables etc.,

The word “ Internet” actually refers to all the hardware infrastructure present in the network. Such hardware include computer systems, routers, cables, bridges, servers, cellular towers, satellites and other pieces.

All these pieces of hardware operated under the Internet Protocol(IP).

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Vinton Cerf

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Father of Internet

Co-designer of the TCP/IP networking protocol.

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WWW( World Wide Web)The WWW is the collection of all the information that is available in the Internet. So all the text, images, audio, videos online- all this forms the WWW.

Most of these information is accessed through websites and we identify websites by their domain names.

There is huge amount of information available in the WWW.

Only a tiny part of this information is searchable through popular search engines like Google.

WWW uses htttp protocol to access the information from various servers.

Tim Berners-Lee

Father of W W W.

The inventor of HTML.

Invented WWW while working at CERN, the European Particle Physics Laboratory.

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Difference between Internet and WWW.

Internet WWW

Internet originated sometimes in late 1960’s

English scientist Tim Berners-Lee invented the WWW in 1989

Nature of Internet is hardware Nature of WWW is software

Internet consists of Computers, Routers, Cables, Bridges, Servers, Cellular towers.

WWW consist of information like text, image, audio, video.

The first version of Internet was known as ARPANET

In the beginning the WWW was know as NSFNET

Internet works on basis of Internet Protocol(IP).

WWW works on basis of Hyper Text Transfer Protocol(HTTP).

Internet is independent of WWW. WWW requires internet to exist.

Internet is superset of WWW. WWW is subset of the Internet. Apart from supporting WWW, the Internet infrastructure is used for other things as well(eg. FTP, SMTP).

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Internet Map

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How to access the Internet?To access the Internet, an existing network need to pay a small registration fee and agree to certain standards based on the TCP/IP (Transmission Control Protocol/Internet Protocol) reference model.

Each organization pays for its own networks and its own telephone bills, but those costs usually exist independent of the internet.

The regional Internet companies route and forward all traffic, and the cost is still only that of a local telephone call.

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How to access the Web?

Once you have your Internet connection, then you need special software called a browser to access the Web.

Web browsers are used to connect you to remote computers, open and transfer files, display text and images.

Web browsers are specialized programs.

Examples of Web browser: Netscape Navigator (Navigator) and Internet Explorer.

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Client/Server Structure of the WebWeb is a collection of files that reside on computers, called Web servers, that are located all over the world and are connected to each other through the Internet.

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

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

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Client/Server Structure of the Web

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Web Browser

A web browser is a software application used to locate, retrieve and display content on the world wide web including web pages, images, video and other files.

As a client/server model the browser is the client run on a computer that contacts the web server and requests information,

The Web Server sends the information back to the browser which displays the results on the computer or other Internet enabled device that supports a browser.

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Commonly used Web Browser

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Web PageA document which can be displayed in a web browser such as Google Chrome, firefox. These are also called as “Web pages” or “pages”.

A Web page is accessed by entering a URL address and may contain text, graphics and hyperlinks to other Web pages and files.

Once in a browser, you can open a webpage by entering the URL in the address bar.

For example, typing http://www.computerhope.com/esd.html opens the Computer hope’s esd page.

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Website

A collection of Web pages which are grouped together and usually connected together in various ways. Often called a “Web site” or simply a “site”.

A Website is a central location of various web pages that are all related and can be accessed by visiting the home page using a browser.

For example, our college website spcputtur.org which contains number of WebPages.

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Web Server

Web servers are software applications running on Web sites that handle requests from Web browsers.

Servers "serve up" Web pages to a Web browser.

Web server software returns Web pages (including pictures, audio and possibly video), encoded in HTML, back to their Web browser clients.

More importantly, Web servers can capture information from users and start up other server-resident programs. This opens the door to accessing corporate databases and legacy COBOL applications from the Web.

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Types of Web Server

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HTMLIn 1980, Physicist Tim Berners-Lee introduced HTML language.

It is the authoring language used to create documents on the World Wide Web.

HTML defines the structure and layout of a web document by using a variety of tags and attributes.

HTML is the standard markup language for creating web pages and web applications.

HTML elements are the building blocks of HTML pages.

With HTML constructs, images and other objects, such as interactive form can be embedded into the rendered page. 20

Structure of HTML code

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Example For HTML Code

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IP Address

The combination of the four IP address parts provides 4.2 billion possible addresses (256 x 256 x 256 x 256).

This number seemed adequate until 1998.

Members of various Internet task forces are working to develop an alternate addressing system that will accommodate the projected growth.

However, all of their working solutions require extensive hardware and software changes throughout the Internet.

Example for IP address: 192.168.9.1

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Domain Name SystemMost web browsers do not use the IP address t locate Web sites and individual pages.

They use domain name addressing.

A domain name is a unique name associated with a specific IP address by a program that runs on an Internet host computer.

This program, which coordinates the IP addresses and domain names for all computers attached to it, is called DNS (Domain Name System ) software.

The host computer that runs this software is called a domain name server.

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Domain Name System

Domain names can include any number of parts separated by periods, however most domain names currently in use have only three or four parts.

Domain names follow hierarchical model that you can follow from top to bottom if you read the name from the right to the left.

For example, the domain name gsb.uchicago.edu is the computer connected to the Internet at the Graduate School of Business (gsb), which is an academic unit of the University of Chicago (uchicago), which is an educational institution (edu).

No other computer on the Internet has the same domain name.

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Structure of a Uniform Resource Locators

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Uniform Resource Locator

Is defined as the global address of document and other resource on the WWW.

URL is an address that sends users to a specific resource online, such as webpage, video other document or resource.

A URL is one type of Uniform resource identifier (URI); the generic term for all types of names and addresses that refer to objects on the WWW.

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HTTPIs an application protocol for distributed, collaborative, hypermedia information systems.

The transfer protocol is the set of rules that the computers use to move files from one computer to another on the Internet.

The most common transfer protocol used on the Internet is the Hypertext Transfer Protocol (HTTP).

Two other protocols that you can use on the Internet are the File Transfer Protocol (FTP) and the Telnet Protocol

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Difference between HTTP & HTTPs

HTTP HTTPS

1) URL begins with “http://” 1) URL begins with “https://”

2) It uses port 80 for communication 2) It uses port 443 for communication

3) Unsecured 3) Secured

4) Operates at application layer 4) Operates at transport layer

5) No encryption 5) Encryption is present

6) No certificates required 6) Certificate Required.

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