Color isn't a property of objects—it's a construction of the brain. When light enters the eye, photoreceptors respond to different wavelengths, and the brain interprets these signals as the rich palette we experience.
Human color vision relies on three types of cone cells, each sensitive to different wavelength ranges roughly corresponding to red, green, and blue. The brain combines signals from all three to create millions of distinguishable colors.
Color perception varies between individuals. About 8% of men and 0.5% of women have some form of color blindness, usually affecting red-green discrimination. Tetrachromats—mostly women—may have four cone types, potentially perceiving colors invisible to typical trichromats.