Used in histology and pathology laboratories to differentiate stained tissue sections, particularly in the Hematoxylin and Eosin (H&E) staining process. After tissues are stained with hematoxylin, this solution helps remove excess dye and reduces non-specific staining, enhancing nuclear contrast. The acid component selectively removes hematoxylin from areas where it is loosely bound, such as cytoplasm and background regions, while retaining it in cell nuclei. This step sharpens tissue morphology, allowing for clearer microscopic examination and more accurate diagnosis. After differentiation, tissues are rinsed and counterstained with eosin to visualize cytoplasmic structures. Proper control of differentiation time and solution concentration is critical to avoid over- or under-differentiation, ensuring consistent and reliable staining results.