FM is short for frequency modulation, which refers to the means of encoding the audio signal on the carrier frequency. FM full power, low power, translator and booster stations operate in the 88 – 108 MHz band. There are many classes of radio stations. The smallest provide service to areas within three or four miles of a transmitter site; the largest provide service to locations more than 60 miles from a transmitter site. Only noncommercial educational radio stations are licensed in the 88-92 MHz “reserved” band. Both commercial and noncommercial educational stations may operate in the “non-reserved” 92-108 MHz band.