what is a carrier wave?

Intelecommunications, acarrier signal,carrier wave, or justcarrier, is awaveform(usuallysinusoidal) that ismodulated(modified) with aninput signalfor the purpose of conveying information.This carrier wave is usually a much higherfrequencythan the input signal. The purpose of the carrier is usually either to transmit the information through space as anelectromagnetic wave(as in radio communication), or to allow several carriers at different frequencies to share a common physical transmission medium by frequency division multiplexing(as, for example, acable televisionsystem). The term is also used for an unmodulatedemissionin the absence of any modulating signal.