Electromagnetic radiation with
wavelengths between 400
nanometers and 750 nanometers. Electromagnetic radiation within this range can be detected by the
human eye. Colors depend on the wavelength lengths; a short wavelength (the 400 nm side) looks
blue and a long wavelength (the 750 nm side) looks
red.
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.