Q. Why we use Modem?

A Modem is one device which most computer users who have surfed Internet are aware of.  A modem is neededsincehowever most of telecommunications have become digital most telephone connections at user end are still analog POTS (Plain Old Telephone Systems/Sets/Service). But the computer is a digital device and henceforth another device is requiredthat can convert digital signals to analog signals and vice-versa.  Such a device is Modem. Modem signifies Modulator/Demodulator.  Modulation is process that puts digital information on to analog circuit by modifying a constant wave (signal) known as the Carrier.  This is what happens whenever you press a button to connect to Internet or to a web site.  Demodulation is reverse process that derived digital signal from modulated wave. This is what happens when you receive data from a website which then gets displayed by your browser.