Used in microbiology to differentiate enteric bacteria based on their ability to ferment sugars, produce hydrogen sulfide, and generate gas. It helps identify members of the Enterobacteriaceae family by observing color changes and precipitation in the agar. The presence of three sugars allows observation of fermentation patterns—glucose, lactose, and sucrose utilization. Organisms fermenting glucose produce acid, turning the medium yellow, while those fermenting lactose or sucrose show similar changes in the slant. Hydrogen sulfide production is detected by black precipitate formation due to iron sulfide. Gas production may be indicated by cracks or bubbles in the agar. Commonly used in clinical labs to distinguish pathogens like Salmonella and Shigella from other gut flora.