MODEMperforms the task of Modulation at sender’s site and DEModulation at the receiver’s end. Basically, our computer generates data in the form of digital signals which needs to be forwarded to the receiver through telephone lines. Since, telephone lines can carry only analog signals. So digital signals need to be converted to analog signals at sender’s site this is called modulation. At receiver’s end again analog signals should be converted back to the original digital signals, then this is called demodulation.