Lig is elektromagnetiese straling waarvan die frekwensie van so 'n aard is dat dit deur die menslike oog waargeneem kan word.
Visible electromagnetic radiation. The human eye can typically detect radiation (light) in the wavelength range of about 400 to 750 nanometers. Nearby shorter and longer wavelength ranges, although not visible, are commonly called ultraviolet and infrared light.