Computer Network

Computer network is a group of computers and other computing hardware devices (such as printers, scanners, modems, CD drives, etc.) connected to each other electronically through a communication medium. They can communicate with each other, exchange commands, share data, hardware and other resources. Computers on a network may be linked through cables, telephone lines, radio waves, satellites or infrared light beams.

Need for network

Resource sharing: The sharing of available hardware and software resources in a computer network is called resource sharing. For example, the contents of a DVD placed in a DVD drive of one computer can be read in another computer. Similarly, other hardware resources like hard disk, printer, scanner, etc. and software resources like application software, anti-virus tools, etc. can also be shared through computer networks. 

Communication: Computer network helps user to communicate with any other user of the network through its services like e-mail, chatting, video conferencing etc. For example, one can send or receive messages within no time irrespective of the distance. 

Reliability: It is possible to replicate or backup data/information in multiple computers using the network. For example, the C++ files, photos or songs saved in one computer can also be saved in other computers in the same network. These can be retrieved from other computers in which they are saved in case of disasters (malfunctioning of computers, accidental deletion of files, etc.) 

Scalability: Computing capacity can be increased or decreased easily by adding or removing computers to the network. In addition to this, the storage capacity of networks can also be increased by including more storage devices to the network. 

Bandwidth : 

Bandwidth measures the amount of data that can be sent over a specific connection in a given amount of time. Imagine you are in a highway or a public road. The bigger the road, the more will be the number of vehicles that can travel on it. Moreover, the traffic here is faster than on a narrow road. On a narrow road, the traffic is likely to be congested. We can say that the bandwidth of a bigger road is higher than a narrow road. Bandwidth describes the maximum data-transfer rate between computers in a network. In digital systems, bandwidth is measured in bits per second (bps). If the bandwidth is more, data travels faster and hence large amounts of data can be transferred within a particular time span across the network. For example, an Internet connection via cable modem may provide 25 Mbps of bandwidth.

 Noise : 

Noise is unwanted electrical or electromagnetic energy that lowers the quality of data signals. It occurs from nearby radio transmitters, motors or other cables. The transfer of all types of data including texts, programs, images and audio over a network is adversely affected by noise. 

Node : 

Any device (computer, scanner, printer, etc.) which is directly connected to a computer network is called a node. For example, computers linked to the computer network in the school are nodes. When we connect the Internet to our computer, our computer becomes a node of the Internet

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