WHAT IS NETWORK????

A network is a group of  two or more computer system linked together. Computers on a network are sometimes called nodes. Nodes can include hosts such as personal computers, phones, servers as well as networking hardware. Two such devices are said to be networked together when one device is able to exchange information with the other device. 

Computer networks differ in the physical media used to transmit their signals, the communications protocols to organize network traffic, the network's size, topology and organizational intent. A computer network facilitates interpersonal communications allowing people to communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls and video conferencing. 

Important feature of many networks is to provide access to information on shared storage devices. Besides that, a network allows sharing of files, data, and other types of information giving authorized users the ability to access information stored on other computers on the network. Users may access and use resources provided by devices on the network such as printing a document on a shared network printer. A computer network may be used by computer crackers to deploy computer viruses or computer worms on a devices connected to the network or to prevent these devices from accessing the network.

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Types of Networks :

NETWORKS	DESCRIPTION
local-area networks (LANs)	The computers are geographically close together (that is, in the same building).
wide-area networks (WANs)	The computers are farther apart and are connected by telephone lines or radio waves.
metropolitan-area networks MANs)	A data network designed for a town or city.
home-area networks (HANs)	A network contained within a user's home that connects a person's digital devices.
campus-area networks (CANs)	he computers are within a limited geographic area, such as a campus or military base.