what is modulation??

MODULATION

Modulation is a fundamental requirement of a communication system.Modulation may be defined as a process by which some characteristic of a signal known as a carrier is varied according to the instantaneous value of another signal known as modulating signal.the signals containing intelligence of information to be transmitted are called modulating signal.these modulating signals containing intelligence or information to be transmitted are called modulating signals.These modulating signals containing information are also called baseband signals.Also the carrier frequency is greater than the modulating frequencies and the signal which results from the process of modulation is known as modulated signal.Modulation may be classified as continuous wave modulation and pulse modulation.If the carrier wavefrom is continuous in nature then the modulation process is called as continuous-wave(CW)modulation.the example of this type of modulation are amplitude modulation and angle modulation

A modulation is method or process send the information signal with the help of carrier signal that means is two signals are used namely the modulating signal(information signal) and the carrier.
carrier is a high frequency sinusoidal signal.
In the modulation process,some parameter of the carrier wave is varied in accordance with the information signal.
 

suppose that you want to send a information signal to another person..you are a transmitter  and person is a receiver. a distance between to transmitter and receiver there have many noise and traffics in this time your information signal losses the power that way receiver is not found your information signal. because the voice signal(in the electrical form )cannot travel long distance in air.
How to overcome this situation ?we are used to modulation technique.
 In the process of modulation ,the carrier wave actually acts as a carrier which carriers the information signal from the transmitter to receiver.
let's take a example :

 you want to go  to a market and  how to you will  go?? you choose a vehical like car,bus,taxi etc.. and you are a passenger... home to market your distance..
  suppose that a carrier signal is a car..and you are a information signal. source to destination you will go  with the help of carrier this all prosecc is called modulation

carrier

you as a (information)

go to market with the help of carrier