Bacterial stains are techniques used in microbiology to visualize and differentiate bacteria under a microscope. These stains help highlight specific structures within bacterial cells, such as the cell wall, allowing scientists to identify and classify different types of bacteria. Common staining methods include the Gram stain, which categorizes bacteria into Gram-positive and Gram-negative based on their cell wall composition. Staining is essential for diagnosing infections and understanding bacterial behavior. Other staining techniques, like the acid-fast stain, are used for specific bacteria, such as those in the Mycobacterium genus. Overall, bacterial stains are crucial tools in microbiological research and clinical diagnostics.