Stain

Stain refers to a coloring agent used to visualize microorganisms on a medium. A stain can bind specifically to certain cellular components like proteins or lipids. Gram staining is a type of differential stain that differentiates bacteria based on cell walls. Acid-fast stains are used to detect mycobacteria, which have unique thick cell walls. The Gram stain remains one of the most widely used methods in microbiology labs.