Carrier wave

A carrier wave is a waveform (usually sinusoidal) that is modulated (multiplied) by a signal that is to be transmitted. This carrier wave is of much higher frequency than the modulating signal(the signal which contains the information).

The reason for this is that it is much easier to transmit a signal of higher frequency, and the signal will travel further.

Carrier waves are used when transmitting radio signals to your radio. Frequency modulation (FM) and Amplitude Modulation (AM) both get transmitted with the help of carrier frequencies. The frequency you select to tune into your favourite radio station is actually the carrier wave's frequency.