INTRODUCTION OF INTERNET

Keywords :-

HISTORY OF INTERNET
HOW THE INTERNET WORKS
WHAT IS MODEM , WI-FI
ISP (internet service provider)
INTERNET RELATED TERMINOLOGY
WEB ADDRESSES

INTERNET

internet is interconnection between several computer of different types belonging to various networks all over the world. It is a network of networks. millions of people throughout the world use internet to share information and idea, to search information in any topics, etc. All these activities are possible because many of networks are connected to the internet.

HISTORY OF INTERNET

In 1969, the Department of Defence (DOD) of Union State of America started a network called ARPANET (Advance Research Projects Administration Network). It was stared with one computer in California and three in Utah.
Later, the military allowed universities to join the network of sharing the hardware and software resources. Then it grew bigger and gave birth to present day very popular internet.

HOW THE INTERNET WORKS

When information is passed from one computer system to another computer system it is broken up into pieces called PACKETS using the TCP protocol. Using the IP protocol, a message consisting of not more then 1500 bytes or character is put into a packets. Each packet has the address of the sender and destination. These address are called IP ADDRESS.

The packets are passed from one network to another until they reach their destination. At the destination the TCP software reassembles the packet into a complete message. If packets are lost or damaged, a request is sent to resend them. It is not necessary for all the packets in the single message to take the same route through the internet or for the same message to take the same route each time it is sent.

WHAT IS MODEM / WIFI

MODEM :- A modem is computer peripheral that allows you to connect and communicate with other computers via telephones lines.

INTERNAL MODEM :- An internal modem slips into an expansion slot provide in the computer. The phone-cord is plugged into jack, accessible through the back of the computer. The internal modem is less expensive then an external modem.

EXTERNAL MODEM :- An external modem is placed outside a computer. The modem rests the near the telephone that hooks the computers to the outside world.

The modem also enables us to send a fax from our computer to a fax machine. We can also send a fax from our computer to another computer with its help.

WI-FI

Wifi is the name of a wireless networking technology that uses radio waves to provide wireless high speed internet and network connection. A common misconception is that the term Wi-Fi is short for "wireless fidelity", however this is not the case. Wi-FI is simple a trademarked phrase that means IEEE802.11x.

How Wi-Fi Networks Works

Wifi networks have no physical wired connection between sender and receiver by using radio frequency technology -- a frequency within the electromagnetic spectrum associated with radio wave propagation. When an RF current is supplied to an antenna, an electromagnetic field is created that then is able to propagate through space. The cornerstone of any wireless network is an access point (AP). The primary job of an access point is to broadcast a wireless signal that computer can detect and "tune" into. In order to connect an access point and join a wireless network, computers and devices must be equipped with wireless network adapters.

ISP (internet service provider)

Internet connection are are provided by internet service provider (ISP) who install a main server and through the server they gives connection to users. Server is a computer with high storage capacity and memory. It is in turn connected to other servers installed at different places in the world through satellite. Connections issued through the servers are alloted private place in the servers in order to store the E- mails for the connected user.

Some of the ISP's are :-

1. VSNL (Videsh Sanchar Nigam Limited)

2. MTNL (Mahanagar Telephone Nigam Limited)

3. Mantra online

4. NetCracker

5. satyam

NOTE :- Internet Service Providers give us the facility to gain access to the Internet against a fee.

INTERNET RELATED TERMINOLOGY

1. WWW (world wide web)

World wide web is a series of servers that are interconnected through hypertext,
Hypertext is a method of presenting information in which contains text is highlighted that ,when selected, displays more information on that particular topics. These highlighted items are called Hyperlinks and allow the user to negative from one document to another that can be located on different servers.

2. WEB PAGE

The world wide web comprises a larger collection of documents called web pages.
A web pages in an electronics documents written in computer language called HTML. (HYPERTEXT MARKUP LANGUAGE). Each web has unique address called URL (UNIFORM RE-SOURCE LOCATOR ) that identifies its location on the internet. A website has one or more related web pages. A web pages on a site are linked together through a system of hyperlinks, enabling you yo jump between then by clicking on the link . On the web, you navigate through pages of information according to your interests.

3. WEBSITE

A web site is a related collection of world wide web (WWW) files that include a beinging files called a home page. A company or an individuals tells you how to get their web site by giving you the address of their home pages From the home pages, you can get to all the other pages on their site. For example, the web site for google has the homepage address of http:/www.google.com.The homepage leads thousands of pages .A web site many consist of thousand of file spreads out over many servers in worldwide locations.

4. WEB SERVER

A web server is a computer program that serves requested HTML pages or files . A web client is requesting program associated with the user. The web browser in your computer is a client that request HTML files from the web servers. so, a web server is a program that uses the client / server model and the world wide web's HYPERTEXT TRANSFER PROTOCOL (HTTP), and serves the files from the web pages to web user. Every computer on the internet that contains a web site must have web server program. some of the examples of web servers are APACHES , IIS (MICROSOFT'S INTERNET I FORMATION SERVER), etc

WEB ADDRESSES

Internet has more than a million computers attached to it. In order to communicate, every computer connected to the internet has unique address whose format has define by the internet protocol (IP) addressing system. Each computer on the network is called a host, and has a name and a number that identifies it. The IP addressing system uses.

1. Letter addressing system

For example of letter addressing system are
a. cbseindia.org

b. hotmail.com

The last three letter of address are important because they provide information about the kind of organization to which the address belongs. Some of the abbreviations used are listed below .

edu - Educational institutions

com - Commerical organization

org - Nonprofit organizations

gov - Government department

net - Networking organizations

The letter addressing system also uses country codes comprising two letters, Examples of country codes are -

ca for canada

jp for japan

in for india

uk for united kingdom

The letter addressing system is called THE DOMAIN NAMING SYSTEM (DNS).

2. Number addressing system

A numberic addresss called IP address is made up of four numbers, each less than 256, 192. 12 . 248 . 73 or 131. 58 . 97. 254