Color fastness refers to the ability of a material, such as fabric or dye, to retain its color when exposed to various conditions. These conditions can include washing, sunlight, and rubbing. High color fastness means that the color will not fade or bleed easily, ensuring that the item maintains its appearance over time. Testing for color fastness is important in industries like textiles and fashion. Manufacturers often conduct tests to determine how well a dye holds up under different circumstances. This helps consumers choose products that will last longer and look better, contributing to overall satisfaction with items like clothing and upholstery.