The purely sinusoidal component of a complex waveform that carries a signal from a transmitter to a receiver. The carrier wave itself cannot transmit information but must be changed or modulated, two common methods for doing so being amplitude modulation and frequency modulation.
A carrier wave is a waveform (usually sinusoidal) that is modulated (modified) to represent the information to be transmitted. This carrier wave is usually of much higher frequency than the modulating signal (the signal which contains the information).
See amplitude modulation.