Schiff's reagent is a chemical solution primarily used in analytical chemistry to detect the presence of aldehydes and ketones through a specific reaction known as the Schiff test. In this reaction, aldehydes reduce the reagent, producing a distinct magenta color that allows for easy visual identification. It is also employed in microbiological staining procedures, such as the periodic acid-Schiff (PAS) method, to identify bacteria, fungi, and other microorganisms under a microscope by highlighting carbohydrate-rich structures. Additionally, Schiff's reagent finds applications in the food and pharmaceutical industries for quality control and purity testing of products containing carbonyl compounds.