Bandwidth is used with electromagnetic spectrum (for example, radio waves, light waves and X-rays). Such waves are oscillations of electric and magnetic fields. For example, the lowest United States AM radio channel has the band of frequencies from 535,000 Hz to 545,000 Hz. It has a bandwidth of 10,000 Hz (545,000 - 535,000 = 10,000). All United States AM radio broadcasting stations have this bandwidth (But, the location of each band is distinct). The lowest United States FM radio channel has the band from 88,000,000 Hz (88 MHz) to 88,200,000 Hz (88.2 MHz). It has a bandwidth of 200 kHz. You can see that the width of an FM band is 20 times the width of an AM band.