'4'-Aminoazobenzene-4-sulphonic acid is a multifunctional dye essential for various biological experiments, aiding researchers in observing and analyzing cell structures, tracking biomolecules, evaluating cell functions, distinguishing cell types, detecting biomolecules, studying tissue pathology, and monitoring microorganisms. Its applications extend from basic scientific research to a broad spectrum of clinical diagnostics, while also being widely utilized in traditional fields like textile dyeing and emerging domains such as functional textile processing, food pigments, and dye-sensitized solar cells.