CIE Standard Illuminant D65 is a standard light source defined by the International Commission on Illumination (CIE). It simulates average daylight with a color temperature of approximately 6500 Kelvin, making it a common reference for color measurement and reproduction in various industries, including photography and printing. D65 is widely used in color science because it provides a consistent basis for comparing colors under natural lighting conditions. This standard helps ensure that colors appear the same across different devices and media, promoting accuracy in color matching and quality control processes.