Distinguish between modulation and demodulation.

Hint -Basic difference between the modulation and demodulation is, modulation is to transfer the message signal by adding it with the carrier signal while demodulation is the process of filtering out the actual message signal from the carrier signal.

Complete step-by-step answer:
(1) Imposing the data information on the carrier signal is modulation while the recovery of the original information from the carrier signal is demodulation. In other words, modulation is the variation of the parameter of carrier signal in proportion to an information signal while demodulation is the regeneration of the information signal.
(2) The modulation is done to send the message signal and demodulation is done to receive the message signal. That means modulation is done at the sending station while demodulation is done at the receiver station.
(3) Modulation is done to save the message signal from any noise during the transmission while demodulation is done to get the actual message which is sent by the sender without any distortion or any additional signal.
(4) Modem is the device which performs both modulation and demodulation.
(5) In a simple concept we can understand modulation and demodulation as analogy to digital conversation (ADC) and digital to analogy conversation (DAC). But in the practice modulation and demodulation is done in the digital domain while actual transmission and receiving are performed in the analogue domain.

Note- To make the transmission smooth, efficient and proper we perform modulation and demodulation. The information signal or the message signal which we have to send may be analogue or digital. Carrier is always analogue which is of much higher frequency.