Eosin Y water solution is widely used in biological staining, particularly in histology and pathology. It is a popular counterstain in hematoxylin and eosin (H&E) staining, where it highlights cytoplasmic components, collagen, and muscle fibers, providing contrast to hematoxylin-stained nuclei. This aids in the microscopic examination of tissue samples for diagnostic purposes. In addition to histology, it is employed in fluorescence microscopy as a fluorescent dye to study cellular structures and processes. It is also used in viability assays to differentiate between live and dead cells, as it selectively stains non-viable cells. Eosin Y water solution finds applications in the textile industry as a dye for fabrics and in the cosmetic industry for coloring products like lipsticks and nail polishes. Its vibrant color and staining properties make it a versatile compound across various fields.