Wavelength and frequency are important because every frequency has its place on the electromagnetic spectrum. Also electromagnetic spectrum has many different wavelengths and frequencies on it . We only see a small fraction of what is created. The wavelength and frequency differs from wave to wave. You go from the lower frequency microwaves all the way up to the high frequency of gamma rays. It is important to determine the "type" of light because different wavelengths have different pulsation speed. The gamma rays pulse much faster then the light we see, and the light we see also goes faster than microwaves.
