Used primarily as a dye in the textile industry to color fabrics, especially denim, giving them the classic blue hue. Its derivative, indigo carmine, is employed in the food industry as a coloring agent known as E132 to add blue color to various products like candies, beverages, and desserts. Additionally, indigo carmine finds application in biological staining for microscopy to highlight specific structures in cells and tissues. Pure indigotin is valued for its stability and non-toxic nature, making it suitable for use in cosmetics such as hair dyes. It is also used in art and printing to create unique blue colors.