Yesterday, I gave you a pretty confusing explanation of how AM (amplitude modulation) and FM (frequency modulation) worked.
Here’s a film from our military that explains how the two bands differ.
They also explain the carrier frequency (or rest frequency), which is the frequency you tune your radio when you listen to a particular radio station, such as 90.7 MHz when you want to listen to Fordham’s own WFUV-FM. In the case of FM, the frequency is modulated but centered at that rest frequency.