Modulator-demodulator. Digital-to-analog, and back, signal converter. Allows computers to communicate over telephone wires or cable TV cable. Computer’s digital signals become analog signals for transmission. The receiving computer’s modem reconverts the analog signals into digital signals. Signal conversion is called modulation. Reconversion to the original type is demodulation. Earlier modems worked at 56 thousand bits per second (Kbps) or higher data transfer speeds, autocorrect errors, and support voice and fax communications. Current modems, like cable modems push 2 million bits per second (Mbps) or higher speeds. Advanced telephone services like ISBN push even higher speed data transfer without modems.