5-Bromomethyl-fluorescein is a versatile dye utilized in various biological experiments. Dyes are crucial for observing cell structures, tracking biomolecules, evaluating cellular functions, distinguishing cell types, detecting biomolecules, studying tissue pathology, and monitoring microorganisms. Their applications extend from fundamental research to clinical diagnostics. Additionally, dyes are employed in traditional areas like textile dyeing and in new areas such as functional textile processing, food pigments, and dye-sensitized solar cells.