What is computer Network,data communication ,data communication modes

 Computer Network 
A network consist of two or more separate devices that are linked together so they can communicate. 
Inter connected collection of dependents computers is called network.
Simply two or more computer  are connected together for  interchange information they form a Network.

What is Data Communication
Data communication is the exchange of information from one computer / entity to the other using transmission medium.
Sending of information in any form, from one place to another place using electronic devise is called telecommunication or Data communication.
Elements Of Data Communication
A data communication is made up five components.

1. Message 
2. Sender  
3. Receiver
4. Medium/ Channel
5. protocols
1. Message:
Information to be communicated.
It can be text numbers, audio, video, images, or combination of all these. 
2. Sender: 
A sender is the device which sends the message. E.g Computer, Telephone, Video Camera, fax machine, etc.
3. Receiver:
A device which receive the message , Computer, Telephone etc.
4. Medium / Channel:
The Medium is the actual path on which the message travels from sender to receiver.
Can be wired or wireless.
5. Protocol: 
Protocol is a set of rules that govern communication.
Without protocol two  people may connected but they will not be able to communicate.

Data Transmission modes

The way in which the data is transmitted from one place to another is called data transmission modes.

There are three types of data transmission they are follows.

1. Simplex Mode

2. Half duplex Mode

3. Full Duplex Mode

1.  Simplex

In simplex mode, data can flow only in one direction. It cannot be moved in both directions. The direction of flow never change. 

A device with simplex mode can either send or receive data. It can’t perform both side.

Example: TV broadcast. The signal is sent from the transmitter to TV  antenna. There is no return signal.

2.  Half-Duplex

In half duplex mode, the data can flow in both directions but not at the same time. It transmitted one-way at one time. 

A device with half- duplex mode can send or receive data but not at the same time. That is why the speed of half-duplex mode is slow.

Example: Police pocket phone, internet suffering.

3.  Full-Duplex

In full-duplex mode, data can travel in both directions simultaneously. Full duplex mode is a faster wary of data transmission as compared to half duplex.

Time is not wasted in changing the direction of data flow.

Example: Telephone, both person can talk at the same time.