Visible Light Spectrum:

The small range of the electromagnetic spectrum that human eyes perceive as light. Ranges from about 400 to 700 nm, corresponding to blue through red light

Visible Light Spectrum:

Electromagnetic radiation with wavelengths between 400 nanometres and 750 nanometres. Electromagnetic radiation within this range can be detected by the human eye. Colours depend on the wavelength lengths, a short wavelength (the 400 nm side) looks blue and a long wavelength (the 750 nm side) looks red.