The term modem was derived from the words modulator and demodulator. Standard telephone lines were originally designed to carry analog signals such as sound waves. These analog signals are of no use to modern day computers because computers require digital signals which are comprised of ones and zeros. For computers to have the ability to transmit data across these existing analog phone lines there signals have to be modulated or converted into analog sound wave form and then demodulated or converted back into a digital form that the receiving computer can understand.
