The purpose of a communication system is to transfer information from a source to a destination. In practice, problems arise due to noise and other interference. Modulation is a way of sending signals over long distances without a huge loss of energy by the use of another wave of very high frequency called a carrier wave. After modulation takes place and the signal is sent, its the receiver’s job to demodulate the signal and retrieve the original signal. Click on this link to see the simulation of Amplitude Modulation and Demodulation.