Visible light is a form of electromagnetic radiation with wavelengths
between about 400 and 800 nm. It seems silly to talk about "visible"
light; after all, you can always see light, can't you? Yet, there are
the boundary between colors we see well and "colors" we cannot see
at all is not sharp but gradual, so we cannot pinpoint an exact border
between visible and invisible light.
not everybody is equally sensitive to any given color. A color
that is just visible to some may be invisible to some others. Should
such a color be considered to be light or not?
visible light does not differ fundamentally from invisible light
(such as infrared and ultraviolet light) that is just beyond the
Scientists therefore use the phrase "visible light" for the wavelength
range of electromagnetic radiation that the average person can see at
least a little bit, with vague boundaries on the low and high sides.