In aerial and satellite imagery, spectral bands are normally named by the section of the electromagnetic spectrum they describe, such as red, green, blue, NIR, IR, or panchromatic.  Each band is capturing a distinct wavelength range reflected from the surface material in the image. Each band can stand alone as a grayscale image, or can be viewed simultaneously with other bands, each assigned to display in one of the red, green, or blue colour channels on a computer monitor.