1. An electronic device that connects computers via a telephone line, allowing the exchange of information which consists of a modulator to convert computer information into a telephone signal and a demodulator to convert it back again. 2. A blend of modulator and demodulator.

• Modulator: A device that makes alterations in the characteristics of the amplitudes, frequencies, or phases of waves, or the velocity of the electrons in electron beams.
• Demodulator: The use of a nonlinear device in order to recover the original modulating frequencies, because these frequencies are not present in the modulated carrier and new frequencies cannot be produced by a linear device.