Iron Agar is commonly used in microbiology for detecting hydrogen sulfide (H₂S) production by bacteria. It serves as a differential medium that helps identify enteric pathogens, particularly in distinguishing members of the Enterobacteriaceae family. The presence of iron compounds in the agar reacts with H₂S to form a black precipitate (iron sulfide), indicating a positive reaction. This property is especially useful in diagnosing organisms like Salmonella and Shigella. Iron Agar also supports the growth of fastidious organisms and allows observation of bacterial fermentation of carbohydrates through pH indicators. It is widely used in clinical labs for stool culture and in food and water testing to isolate and identify pathogenic bacteria.