Dimidium bromide is a red basic dye primarily used as a redox indicator in analytical chemistry for the titration of reducing substances like sulfides, cyanides, and thiols, exhibiting a color change from red to colorless. In biological and microbiological research, it serves as a vital stain and counterstain in histological and cytological preparations to differentiate cellular components. Furthermore, in the textile industry, it is applied as a dye for natural and synthetic fibers, imparting bright red hues with improved color fastness.