Neutral red is widely used as a pH indicator in biological and chemical experiments, changing color from red to yellow between pH 6.8 and 8.0. It is commonly employed in cell viability assays, where it helps determine the health and survival of cells by selectively staining living cells. In microbiology, it is used to differentiate between live and dead bacteria. Additionally, Neutral red is utilized in histology for staining tissues, particularly in identifying lysosomes in cells. It also plays a role in environmental studies, such as monitoring water quality by detecting toxic substances in aquatic systems.