Modem, MOH duhm or MOH dehm, is a device that enables computers to transmit and receive information over the telephone network. The word modem stands for modulator-demodulator. A modem modulates (translates) a computer's digital electrical signals into tones that can travel over telephone lines. A modem at the other end demodulates (retranslates) the tones back into computer information. Modems can send and receive not only text information but also sound, still pictures, and moving pictures.