CIE Standard Illuminant C is a reference light source defined by the International Commission on Illumination (CIE). It represents a standard daylight illuminant with a color temperature of approximately 6774 Kelvin, simulating average daylight conditions. This illuminant is used primarily in color science and photography to ensure consistent color reproduction. The spectrum of Illuminant C is based on the spectral power distribution of natural daylight, making it useful for color matching and calibration. It serves as a benchmark for evaluating the color rendering properties of various light sources, helping to maintain color accuracy in different applications.