Used as a blue dye in the textile industry, particularly for dyeing cotton to produce denim fabric. Employed in medical diagnostics as a coloring agent during surgical procedures to visualize the urinary tract or identify leaks in tissues. Serves as a pH indicator in analytical chemistry, changing color in response to acidity or alkalinity. Applied in food and pharmaceutical industries as a colorant where permitted, providing a blue or green tint to products. Utilized in microbiology as a redox indicator in culture media to monitor bacterial activity.