The Gram Stain is a laboratory technique used to classify bacteria into two groups: Gram-positive and Gram-negative. This classification is based on the structure of their cell walls, which affects how they retain the stain. The process involves applying a crystal violet dye, followed by iodine, which helps fix the dye. After washing with alcohol, a counterstain, usually safranin, is applied. This method is crucial in microbiology for identifying bacterial species and guiding treatment decisions. Gram-positive bacteria appear purple under a microscope, while Gram-negative bacteria appear pink. The Gram Stain is a fundamental tool in clinical diagnostics and research.