Internet Terms

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General Internet Terms

Application

An application is essentially a collection of programs designed to perform a set of services.

Bandwidth

In the context of data communication and networking, bandwidth refers to the difference (measured in Hz), between the highest and lowest frequencies of a transmission. It is the width of a frequency band.

In the context of the world wide web, bandwidth refers to the amount of data that can be transferred over a network connection.

Client

In Internet context, a client is a specific application that aims to enable user to get a specific service from another computer (referred as server) deployed on the Internet. It essentially provides all the necessary front-end interface for the user to interact with the application residing on the server that delivers the service. Popular examples of clients include - the web browser, FTP client, outlook (an email client). In a more broader context, the entire computer system of the user along with the associated software, is termed as a client machine.

Server

A server is a computer deployed on the Internet to carry out and deliver specific services. For instance, a web server may carry out services such as - serve web pages on request from web browsers, serve files on request from ftp clients, serve emails on request from email clients, etc.

Client-Server

A client-server system is essentially a distributed application environment, where applications may reside on multiple computers (clients and servers) and collectively perform a service.

Terms related to modes of data communication

There are fundamentally three modes of data communication and hence three types of networks have evolved.

Packet Switching

Packet switching is analogous to the postal network. It is a method of data communication in which messages are divided into packets before they are sent. Each packet is transmitted individually and can even follow different routes to its destination and reach in random order. Thus data is transmitted in fragments and the fragments are reassembled at the destination. Packet-switching is more efficient for data that can withstand some delays in transmission � such as emails and web pages.

Circuit Switching

Circuit switching is analogous to the telephone network. In contrast to packet-switching, in circuit switching a dedicated line is allocated for transmission between two computers. This is an ideal mechanism when data is required to be transmitted quickly and must arrive in order. Examples of circuit switched networks are � Telephone System, Real-time data transmission such as live audio and video.

ATM - Asynchronous Transfer Mode

ATM combines the best of the two modes. It establishes a fixed channel or route for communication before data transfer begins. Data is transmitted in cells or packets of fixed size. The relatively small and constant size of the cell enables transmission of audio, video and other computer data over the same network, simultaneously, as no single type of data will be able to hog the line.

Hub and Bridge

Hubs link groups of computers to one another so that they can communicate.

Bridges link two LANs to each other. They enable data emanating from one LAN and destined for the other LAN to be sent to the other LAN.

Gateway and Router

Gateways connect any network to any other network. They provide for protocol translation, framing, error detection, flow control and also routing. Gateway is used as a generic name to often refer to routers and bridges as well.

Routers play a key role in managing Internet traffic. They connect two or more networks and perform the job of directing traffic. They examine each packet to see where the packet is headed. Based on the packet�s destination, the packet is routed in the most efficient way.

Protocol

Protocol is an agreed upon format for transmitting data between two devices. The protocol determines the following:

• The type of error checking to be used.
• How the sending device will indicate that it has finished sending a message.
• How the receiving device will indicate that it has received a message.

The TCP/IP protocol

TCP/IP stands for Transmission Control Protocol/ Internet Protocol. It is a suite of communications protocols used to connect hosts on the Internet. The TCP/IP family of protocols is illustrated in the image below:

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