What is fast coloureds and non fast?

"Fast coloureds" refers to fabrics or materials that retain their color well and resist fading when washed or exposed to light, making them ideal for vibrant clothing and textiles. In contrast, "non-fast" coloured items may lose their color more quickly, requiring special care to maintain their appearance. The distinction is important in industries like fashion and textiles, where durability and color retention are key considerations for consumers.