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What is Internet?
The internet is essentially a global network of computing resources. You can think about the internet as a physical collection of routers and circuits as a set of shared resources or even as an attitude about interconnecting and intercommunication. Some common definitions given in the past include:
  • A network of networks based on the TCP/IP communications protocol.
  • A community of people who use and develop those networks.
 Internet Based Services:
Some of the basic services available to Internet users are:
  • Email: A fast, easy and inexpensive way to communicate with other Internet users around the world.
  • Telnet: Allows a user to log into a remote computer as though it were a local system.
  • FTP: Allows a user to transfer virtually every kind of file that can be stored on a computer from one Internet-connected computer to another.
  • Usenetnews: A distributed bulletin board that offers a combination news and discussion service on thousands of topics.
  • World Wide Web (www): A hypertext interface to internet information resources.
Browser Programs:
A web browser is a software program that enables you to view and interact with any information available on the web.
Web comprises of a number of text files generally written in HTML language that are linked to each other is a specific manner and these text files are called HTML web pages. These web pages can be viewed with the help of a software program known as web browsers. Web browsers acts as a user interface for users to navigate in the web pages, read content and perform actions such as click buttons, clicks on the hyperlinks to another web page, select text, enter URL (uniform resource locator) of a web page to access etc. Web browsers has two main functions namely:

To make a request for a page: This is done by typing in the URL of the web page concerned in the address bar of the web browsers. Similarly, when a hyperlink is clicked the URL of the hyperlink gets automatically populated in the address bar of the browser.

To interpret the HTML page sent to the user from the web server: The formatting is done on the browser and displayed to the user in readable form. The actual page on the web server is in ASCII form. HTML along with Cascading Style Sheets (CSS) are used to present the web pages in web browser.

Examples of web browsers:
Microsoft Internet Explorer, Mozilla Firefox, Google Chrome are popular web browsers.

Internet Explorer:
Microsoft's free Internet Explorer is available primarily for the windows operating system and comes pre-installed. There is also a version of the Macintosh but its development has been stopped by the company.

Firefox-also known as Mozilla Firefox
Firefox, developed by Mozilla Corporation, supposedly offers enhanced security and privacy. The browser is available for various operating systems including Windows, Macintosh, Linux/Unix and can be downloaded for free.

The Opera web browser is credited to have introduced several features one of which is the popular tab browsing, Opera has never been able to gain a substantial market share, however, it has a loyal user base who swear by the browser.

The latest free web browser in the market is Google Chrome. It was launched on the 2nd of September 2008 for the windows operating system. In the short span of a few years, it has become the number one used browser and is available for a variety of platforms including the iPad!

An internet browser first introduced as Mosaic Netscape 0.9 on October 13, 1994, Netscape was popular during the early 1990's and in a browser war with Microsoft Internet Explorer. The popularity and use of Netscape declined in the late 1990's, which led to the open source Mozilla project and the acquisition on November 24, 1998 by AOL for $4.2 billion.

What is WWW?
This stands for World Wide Web. A technical definition of the World Wide Web is: all the resources and users on the Internet that are using the Hypertext Transfer Protocol HTTP.

A broader definition comes from the organization that Web inventor Tim Berners-Lee helped found, the World Wide Web Consortium W3C:

The World Wide Web is the universe of network-accessible information, an embodiment of human knowledge.
In simple terms, The World Wide Web is a way of exchanging information between computers on the internet, typing them together into a vast collection of interactive multimedia resources.

What is HTTP?
This stands for HyperText Transfer Protocol. This is the protocol being used to transfer hypertext documents that makes the World  Wide Web possible.
A standard web address such as is called a URL and here the prefix http indicates its protocol.

What is URL?
URL stands for Uniform Resource Locator, and is used to specify addresses on the World Wide Web. A URL is the fundamental network identification for any resource connected to the web. eg, hypertextpages, images, and sound files.
A URL will have the following format:
The protocol specifies how information from the link is transferred. The protocol used for web resource is HyperText Transfer Protocol HTTP. Other protocols compatible with most web browsers include FTP, telnet, newsgroups, and Gopher.
The protocol is followed by a colon, two slashes, and then the domain name. The domain name is the computer on which the resource is located.
Links to particular files or sub directories may be further specified after the domain name. The directory names are separated by single forward slashes.

What is Website?
Currently you are on my website which is a collection of various pages written in HTML markup language. This is a location on the web where people can find educational materials. Similar ways there are millions of websites on the web.
Each page available on the website is called a webpage and first page of any web site is called homepage for that site.

What is Web Server?
Every web site sits on a computer known as a Web Server. This server is always connected to the internet. Every web server that is connected to the Internet is given a unique address made up of a series of four numbers between 0 and 256 separated by periods. For example, or
When you register a web address, also known as a domain name, such as you have to specify the IP address of the web server that will host the site.
We will see different type of web servers in a separate chapter.

What is Web Browser?
Web Browsers are software installed on your PC. To access the web you need a web browser, such as Netscape Navigator, Microsoft Internet Explorer or Mozilla Firefox.
Currently you must be using any sort of Web browser while you are navigating through my site On the web, when you navigate through pages of information this is commonly known as browsing or surfing.

What is FTP?
FTP is a client-server protocol that relies on two communications channels between client and server: a command channel for controlling the conversation and a data channel for transmitting file content. Clients initiate conversations with servers by requesting to download a file. Using FTP, a client can upload, download, delete, rename, move and copy files on a server. A user typically needs to log on to the FTP server, although some servers make some or all of their content available without login, also known as anonymous FTP.

What is SMTP Server?
This stands for Simple Mail Transfer Protocol Server. This server takes care of delivering emails from one server to another server. When you send an email to an email address, it is delivered to its recipient by a SMTP Server.

What is ISP?
This stands for Internet Service Provider. They are the companies who provide you service in terms of internet connection to the internet.
You will buy space on a web server from any internet service provider. This space will be used to host your web site.

What is HTML?
This stands for HyperText Markup Language. This is the language in which we write web pages for any website. Even the page you are reading right now is written in HTML.
This is a subset of standard generalized mark up language SGML for electronic publishing, the specific standard used for the World Wide Web.

What is Hyperlink?
A hyperlink is simply link in a selectable element in an electronic document that serves as an access point to other electronic resources. Typically, you click the hyperlink to access the linked resource. Familiar hyperlinks include buttons, icons, image maps, and clickable text links.

What is DNS?
DNS stands for Domain Name System. When someone types in your domain name,, your browser will ask the Domain Name System to find the IP that hosts your site. When you register your domain name, your IP address should be put in a DNS along with your domain name. Without doing it your domain name will not be functioning properly.

What is W3C?
This stands for World Wide Web Consortium which is an international consortium of companies involved with the Internet and the web.
The W3C was founded in 1994 by Tim Berners-Lee, the original architect of the World Wide Web. The organization's purpose is to develop open standards so that the web evolves in a single direction rather than being splintered among competing factions. The W3C is the chief standards body for HTTP and HTML.

E-mail (electronic mail) is the exchange of computer-stored messages by telecommunication. E-mail messages are usually encoded in ASCII text. However, you can also send non-text files, such as graphic images and sound files, as attachments sent in binary streams. E-mail was one of the first uses of the internet and is still the most popular use. A large percentage of the total traffic over the internet is e-mail. E-mail can also be exchanged between online service provider users and in networks other than the internet, both public and private.
E-mail is one of the protocols included with the transport control protocol/internet protocol (TCP/IP) suite of protocols. A popular protocol for sending e-mail is simple mail transfer protocol and a popular for receiving it is POP3. Both Netscape and Microsoft include an e-mail utility with their web browsers.

Connecting to the internet with a modem
Connecting to the internet using a computer modem (eg. 56K modem) is still a method of getting access to the internet, despite the growing use of broadband internet connections. Although connecting to the internet with a modem can be a cheaper solution, it is a much slower connection. If you plan on doing more than the occasional web surfing and reading and sending e-mail, you should consider broadband. For example, if you want to play games over the internet, it is recommended that you use a broadband connect instead of a modem.
Using a modem to connect to the internet requires your computer to have an internal or external modem. You must also have a home phone line (landline).

Computer Network:
A computer network is a set of computers connected together for the purpose of sharing resources. The most common resource shared today is connection to the internet. Other shared resource can include a printer or a file server. The internet itself can be considered as a computer network.

Types of Networks
There are several different types of computer networks. Computer networks can be characterized by their size as well as their purpose.
The size of a network can be expressed by the geographic area they occupy and the number of computers that are part of the network. Networks can cover anything from a handful of devices within a single room to million of devices spread across the entire globe.

Some of the different networks based on size are:
Local Area Network, or LAN
Metropolitan Area Network or MAN
Wide Area Network or WAN

In terms of purpose, many networks can be considered general purpose, which means they are used for everything from sending files to a printer to accessing the internet. Some types of networks, however, serve a very particular purpose. Some of the different networks based on their main purpose are:
Storage Area Network, or SAN
Enterprise Private Network, or EPN
Virtual Private Network or VPN
Let's look at each of these in a bit more detail.

Local Area Network:
A local area network, or LAN, consists of a computer network at a single site, typically an individual office building. A LAN is very useful for sharing resources, such as data storage and printers. LANs can be built with relatively inexpensive hardware, such as hubs, network adapters and Ethernet cables.
The smallest LAN may only use two computers, while larger LANs can accommodate thousands of computers. A LAN typically relies mostly on wired connections for increased speed and security, but wireless connections can also be part of a LAN. High speed and relatively low cost are the defining characteristics of LANs.

LANs are typically used for single sites where people need to share resources among themselves but not with the rest of the outside world. Think of an office building where everybody should be able to access files on a central server or be able to print a document to one or more central printers. Those tasks should be easy for everybody working in the same office, but you would not want somebody just walking outside to be able to send a document to the printer from their cell phone! If a local area network, or LAN, is entirely wireless, it is referred to as a wireless local area network, or WLAN.

Metropolitan Area Network
A metropolitan area network, or MAN, consists of a computer network across an entire city, college, campus or small region. A MAN is larger than a LAN, which is typically limited to a single building or site. Depending on the configuration, this type of network can cover an area from several miles to tens of miles. A MAN is often used to connect several LANs together to form a bigger network. When this type of network is specifically designed for a college campus, it is sometimes referred to as Campus Area Network, or CAN.

Wide Area Network:
A wide area network, or WAN, occupies a very large area, such as an entire country or the entire world. A WAN can contain multiple smaller networks, such as LANs or MANs. The internet is the best-known example of a pubic WAN.