A group of autonomous computers and associated devices connected together by communication channels like cables or telephone lines etc. is called a network.
In a network, the computers work as stand alone machines but can communicate with other computers on the network as and when required.

CBSE Notes for Class 9 Foundation of Information Technology – Computer Networking

CBSE Notes for Class 9 Foundation of Information Technology – Computer Networking

The last century was the century of Information Technology revolution. With the great breakthrough in the world of communication by the use of worldwide network of telephone lines, satellite launching and computers, the world has come very close. Sending a letter by post is virtually becoming obselete. Now is the time of e-mail, chats and video conferencing. All this has become possible because of networking.

NETWORK
A group of autonomous computers and associated devices connected together by communication channels like cables or telephone lines etc. is called a network.
In a network, the computers work as stand alone machines but can communicate with other computers on the network as and when required.

Types of Networks
There are mainly three types of networks as discussed below:
1. LAN (Local Area Network): A network spread over a diameter of minimum 1 m to maximum 10 km is called a local area network. It is usually installed within a building or a group of buildings.
2. MAN (Metropolitan Area Network): This type of network spans a small city. It is used by cable (TV) operators for program distribution.
3. WAN (Wide Area Network): This type of network spans an entire country and very often several countries. The speed of data transmission is a bit slower than that of LAN and the error rate is also high as the data has to travel over very long distances.