Basic Terminologies of Internet

Following are some important terminologies of Internet.


1.Website:

A collection of related web pages that you can access electronically is called web site. It contains text, graphics, sound, and video.

2.Home page:

Most websites have a starting point, called a home page. It is similar to a book cover or table of contents for the sits. It provides information about the site's purpose and content.

3.Hyper link:
A hyper linj is a connection between webpage. It can be a part of text or graphics on a web page . When the user click on it, the hyperlink can:

• Take you to a different part of the same page.
• Take you to a different page within the web site
• Take you to a page in a different web site
• Enable you to download file
• Lunch an application, video or sound.

 4.Anchor:
An anchor is a link to different parts of the same web page.

5. Image Map:

Image map is an image whose different parts are linked with different web pages.

6.Frame:

Frames are used to divide a web page into different parts. Different web pages can be displayed in each part.

7.Table:
Table is a collection of  rows and columns to display data in tables in a web page.

8.HTTP:
It stands for Hyper Text Transfer Protocol. It is a communication protocol used to connect to servers on the World Wide Web. The primary function of HTTP is to establish a connection with a Web server and transmit HTML pages to the user's browser. It allows computer users to access the Internet.

9.HTML:
It stands for Hyper Text Markup Language.HTML is the fundamental language to design web pages.

10.Webmaster:
Webmaster is the person who develops and maintains a web site.

11. Domain Name:
Domain name is the unique name given to a web site.This name is linked to a web server where the information of that web site is stored.

12.URL
URL stands for Uniform Resource Locator. The URL is the web address for any given web document . Every web document has a unique URL. Each URL has several parts, which can be demonstrated using the address;
                http: / / WWW.Google.com  /  services / index . html

• http: / / This part of the address indicates that it is a Web page
• WWW This indicates that the Web page you are looking at is part of the World Wide Web . Many Web sites do not use WWW but are still part of the Web.
• Google.com This part of the address is the domain name and indicates the unique address of a Web site.The domain name also often indicates the type of web site.
• / services / The '' / '' symbol indicates you have moved into a specific directory in the Web server. Directories are like the folders on your computer and help to organize Web pages in Web sites. 
• index.htm  A word with ''.htm'' or ''.html'' following it indicates the name of the specific page in the Web site you are looking at.

13.ISP:
ISP stands for Internet Service Provider.It is a company that provides Internet connections. ISP also provides the facilities of Email.A connection from ISP is necessary to connect to Internet.

14.Web Browser:
A web browser is software that is used to view web pages. It acts as an interface between the user and the Internet.It can understand HTML. It can display text and graphics. Browsers are also known as web clients or universal clients .Some examples of web browsers are Internet Explorer, Netscape, Hot java, and Lynx.

15.Web Server:
A web server is a computer that stores information for the users on the Internet.It is much faster and powerful than ordinary computer.It may be located anywhere in the world .Servers are connected to the Internet 24 hours a day.

Services of Internet

Following are some important services of the Internet:

1. World Wide Web (WWW)

WWW stands for World Wide Web. It is also called Web. It provides the facility to publish information on the Internet. It is a collection of documents or web pages stored on computers permanently connected with Internet around the world. 

2. Email (Electronic Mail)

Email stands for Electronic Mail. Email is the exchange of messages and files through Internet. Message can be in the form of graphics, sounds, video or simple text. It is a fast way of sending messages anywhere in the world. One email message can be sent to multiple recipients. Email facility is provided by many Internet Service providers or specialized websites. Yahoo, Hotmail and Gmail are popular examples of email providing websites.

3. Mailing List

A mailing list is a collection of email names and addresses given a single name. An email message sent to a mailing list is received by every person on the list. Different people discuss different topics and distribute their ideas to other people by email. Softwares are available to administrate mailing lists. The most common program is listserv.

4. News Groups

A newsgroup is a discussion group on the Internet. People exchange information on a vast range of topics such as news, business, science and computer. A user sends message to the newsgroup to participate in discussion. Other users in the newsgroup read and reply to the message. A software is required to obtain articles from news server.

5. E-Commerce

E-Commerce stands for electronic commerce. It is a process of carrying out financial and business dealings using Internet. People can buy and sell good on Internet. They can also pay bills using credit card numbers

6. TELNET

TELNET is a program to connect to a remote computer on Internet. A computer can act like a terminal directly linked to remote computer. The user can log on to the computer and use it as if he is connected to the computer directly.


7. FTP
File Transfer Protocol is used on Internet to send files from one place to other. Audio, video, graphics and data files can be uploaded or downloaded using this protocol. A process of transferring a file from a local computer to remote computer is called uploading. Different software are available to use this protocol for transferring files on the Internet. CuteFTP and WD-FTP are examples of FTP software.


8. Chatting & Instant Messaging

Chatting is a process of exchanging views on the Internet by typing text messages in real-time. Internet Relay Chat (IRC) is a service is used to communicate to each other on hundreds of channels. Instant messaging is a type of chat in which a user on Web can chat with another user currently logged. Most famous is America Online's Instant Messenger.

Uses of Internet

 Internet:
Internet is a collection of millions of computer around around the world that are all connected to one another. It is a global network of computer.These computers are connected through different telecommunications links like:

• Phone lines

• Fiber optics lines

• Satellites and wireless connections 

Internet is used to find information stored on computer called hosts or servers. These computers use a common protocol called TCP / IP for communication. TCP / IP stands for Transmission Control Protocol / Internet Protocol. No government or organization is the owner of Internet. Many people, organizations, universities and research agencies participate to run Internet. Everyone who has access to the Internet can get information from the Internet. Millions of people have access to Internet.

Uses of Internet

Some uses of the Internet are as follows:

• To access information, news, research, and educational material

• To conduct business

• To access source of entertainment such as online games, magazines etc.

• To shop for goods and services.

• To meet and talk with people around the world in discussion groups or chat rooms

• To access other computers and exchange files

• To send messages and receive message from other connected users 

 Working of Internet

The internet is a collection of millions of computers. These computers are linked together on a computer network. The network is used by the computers to communicate with one another. A personal computer can be connected to Internet by using phone lines, DSL or cable modem. These devices communicate with the server of Internet service provider. A user computer is usually connected with ISPs are connected to larger ISPs. Several main transmission media carry the heaviest amount of traffic on Internet. These carries of network traffic are collectively called Internet backbone. Backbone are connected through fiber optic lines, submarine cables or satellite links. In this way, every computer on the Internet is connected to every other computer. The computers connected to the Internet exchange data and information using servers and clients. A client computer accesses data, information and services from different servers. The server computers are also called host computers.

Data Transmission Mode

The way in which data is transmitted from one place to another is called data transmission mode.

Types of Transmission Modes

There are three types of data transmission modes:
1.Simplex Mode

In simplex mode, data can flow only in one direction . It cannot  be moved in both directions. It operates in a manner similar to a one-way street.The direction of flow never changes.A device with simplex mode can either send or receive data. It cannot perform both actions. An example is a traditional television broadcast. The  signal is sent from the transmitter to TV antenna. There is no return signal.

 2. Half - Duplex Traffic:

In half - duplex mode , data can flow in both directions but not at the same time. It is transmitted one - way at one time. A device with half- duplex mode can send or receive data but not at the same time.That is why the speed of half-duplex mode is slow.An example of half-duplex is a narrow bridge that can carry single vehicle at a time .The traffic from side A stops while the vehicles from side B cross the bridge. Similarly, traffic from side B has to stop so that the Vehicle from side A may cross.

3. Full-Duplex Mode

In full- duplex mode, data can travel in both directions simultaneously. Full duplex mode is a faster way of data transmission as compared to half duplex. Time is not wasted in changing  the direction of data flow. A telephone is a full- duplex device . Both persons can talk at the same time.Another example of full- duplex communication is automobile traffic on a two- lane road.The traffic can move in both directions at the samwe time.

Network Topologies

A network can be configured or arranged in different ways. The physical layout or arrangement of connected devices in a network is called topology. It is the shape of a network . Different network topologies are as follows:

• Bus Topology

Bus topology is the simplest type of network.It supports a small number of computers. In bus topology, all computers or network nodes are connected to a common communication medium.This medium is often a central wire known as bus. The terminators are used at the end of a bus to absorb signals.A collision can occur in bus topology if two computers transmit data at same time .Bus topology is mostly used in peer-to- peer networks.

• Working of Bus Network 

 

The sending computer sends the data and destination address through the bus. The data and address move from one computer to the other in the network. Each computer checks the address. If it matches with the address of a computer, the computer keeps the data.Otherwise the data moves to the next computer.
Advantages 

1. It is simple and easy to use.
2. It requires small length of  cable to connect computers. 
3. It is less expensive.
4. It is easy to extend a bus . It allows more computers to join network. 
5. If one node fails, it does not affect the rest of the network.

 Disadvantages 

1. It is difficult to troubleshoot . 
2. It only supports small number of computers.
3. The network speed slows down as the number of computers increases.

 Star Topology

All computers in star topology are connected with central device called hub, star topology is mostly used in client- server networks. 

Working of Star Network

The sending computer sends the data to hub.The hub sends data to the receiving computer. Each computer in star network communicates with a central hub.

Advantages

1. It is easy to maintain and modify network.
2. Adding or  removing computers can be done without disturbing the network.
3.  Finding faults becomes very simple.
4. Single computer failure does not bring down the  whole network.
5. It is more flexible than other topologies.
   

Disadvantages:

1. It central hub fails, the entire network breaks down
2. It requires a large length of cable to connect computers.
3. It is more expensive.

Rind Topology

In ring topology, each computer is connected to the next computer with the last one connected to the first. Thus a ring of computers is formed.

Working of Ring Network

Every computer is connected to next computer in a ring . Each computer  receives message from the previous computer and transmits it to the next computer. The message flows in one direction. The message is passed around the ring until it reaches the correct destination computer.


Advantages

1. It is less expensive than star topology.
2. Every computer has equal access to the network.

Disadvantages

1. Failure of one computer in the ring can affect the whole network. 
2. It is difficult to troubleshoot.
3. Adding or removing computers affect the whole network.

Communication Devices

 The hardware used to transmit data, instructions and information between a sending and  receiving device is called communication device. A communication device at sending end sends data to a communication channel. A communication device at receiving end receives data from communication channel. Some communication devices are as follows: 

Modem

Modem stands for modulation and demodulation. Modem is a device that converts digital signal into analog  and analog signal into digital. Modem sends and receives data from one computer to another  through telephone lines. The sending and receiving computers both must have modems. A process of converting digital signal is called modulation. Computer stores data using telephone line, so it is converted from digital to analog form. A process of converting analog signal into digital signal is called demodulation. The modem on receiving computer receives data in analog form and converts it into digital format to be used by the computer.

Network Interface Card

Network Interface Card (NIC) is also called LAN adapter. It is used to connect a devices to a network. The transfer rate of an Ethernet card is from 10 Mbps to 1000 Mbps to 1000 Mbps. Different NIC are available for different types of computers. Network cards for wireless data transmission are also available. These adapter cards often have an antena.

Wireless Access Point

 A wireless access point is a central communication device. It allows computer and other devices to transfer data wirelessly among themselves or to a wired network.Wirless access points have high quality antennas for optimal signals. Some manufactures suggest to place the wirless access point at the highest possible location for the best signal.




Routers
A router is a communication device that connects multiple computer or other routers together. It connects multiple networks using similar or different protocols. It manages the best route between any two communication networks. Routers are used when several networks are connected together. They can connect networks of different countries. They transfer data in less time. The router is an intelligent device. It uses algorithms to find out the best path to transfer data to network.

HUB

A hub also called concentrator or multistation access unit (MAU). It provides a central point for cables in a network. Hubs also transmit signals and have multiple ports to which devices are connected. It broadcasts all messages to every computer on the network but only the intended recipient  computer takes the message.The computer that are not the recipients of the message ignores the message.A hub can handle only one-way  information traffic at a time.         

Data Communication

Data communication is a process of transferring data electronically from one place to another.Data can be transferred by using different medium.The basic elements of data communication are as follows: 

• Sender: The sender is the device that sends the information. It is also called source. Normally, computer is used as sender in data communication systems.

•  Medium :The medium is the physical path that connects the sender and the receiver.It is used to transmit the data. The medium can be a copper wire,a fiber-optic cable, airwaves etc. It is also called communication channel.

• Receiver: The receiver is the device that accepts the information. It is also called sink . The receiver can be computer, printer or another computer related device.

Types of Data Transmission

The two forms of data transmission are as follows:

1. Digital Data Transmission:

The transfer of data in the form of digital signal is called digital data transmission. Digital signal is a sequence of voltage represented in binary form. The digital signals are in the form of electrical pulses of ON an OFF.

Digital signals are faster and efficient.They provide low error rates . They also provide high transmission speed and high- quality voice transmission. All data communication between the computers is in digital form.Computers understand and work only in digital form. The following figure represents a high voltage as a 1 and a low voltage as a 0.

2. Analog Data Transmission

Analog data transmission is the transmission of data in a continuous wave form.For example sound waves are analog signals. When we talk, we emit sound waves that consist of waveforms of high and low pressure.Analog signal is measured in volts and its frequency is in Hertz (Hz). Telephone line is most commonly used media for analog transmission of data. light, sound, radio and microwave can also be used as analog transmission media.