What is a network?

  • A network is a simple collection of computers.
  • It is when two computers connected as a network at one location that has been tied together using a particular connectivity medium. 
  • Connectivity medium can be network cabling or wireless technology to a giant global network such as the internet that uses a number of different connectivity media, including microwave and satellite technology. 
  • Networks are used to transmit data voice and even video between users on the network.



Local area network

  • A LAN supports fast, low - error data transfer of data. 
  • It covers a small, limited geographic area, such as within a single building or on a single floor of a building.


Metropolitan area network

  • A MAN is a network that spans an area larger than a LAN but is less dispersed geographically than a WAN. 
  • A MAN network may connect several LANs on a single company campus or interconnect the LANs of several companies in one part of town.  


Wide area network

  • A WAN is a network that interconnects LANs and MANs across a broad geographic area.


Use of network -

A network is very important to share information. Users can share resources and communicate within the network.

The major activity that happens is -

  • File sharing
  • Hardware sharing ( printers, CD ROM drivers and hard drives)
  • Program sharing
  • User communication
  • Multiplayer games


  • I’m the year 1984 Open systems interconnection reference model was developed by the ISO international standard organization.
  • The OSI model defines the rules, mechanisms, formats and protocols used to guide how data flows from one device to another.
  • It has 7 layers and they are as follows.

Physical layer

  • The physical layer of the OSI model defines the electrical and mechanical specifications used in Networking. 
  • This includes transmission distances, the various types of media available and electrical issues.

The data link layer

  • The main purpose of the data link layer is for Physical addressing and to notify the errors.
  • It controls the data flow and enables access to the physical medium.

The network layer

  • This layer does the path determination between the source and destination nodes on a different network.
  • Routing messages between networks and
  • Controlling congestion on the subnet

The transport layer

  • Segment and assemble upper layer applications.
  • It transports segment from one body to another host. 
  • Establish and manages end to end operations and error recovery.

The session layer

  • A session is a series of related connection oriented transmissions between network nodes.
  • It establishes and terminates sessions between applications.

Presentation layering

It performs actions like –

  • Data encryption
  • Data compression
  • Data formatting
  • Data conversion

The application layer

It defines the communication services used by the user’s applications to transmit data over the network.




A network can be simply defined as a group of computers and other devices connected in order to exchange data.