Biological stains are substances used to enhance the visibility of biological tissues and cells under a microscope. They work by binding to specific components within the cells, such as proteins or nucleic acids, allowing researchers to observe structures and functions more clearly. Common stains include Hematoxylin, which highlights cell nuclei, and Eosin, which stains cytoplasm. These stains are essential in various fields, including histology, pathology, and microbiology. They help in diagnosing diseases, studying cellular processes, and understanding tissue architecture. Proper use of biological stains can significantly improve the quality of microscopic analysis and research outcomes.