Polyvinyl pyrrolidone, abbreviated as PVP, is a non-ionic polymer compound that is the most distinctive and extensively studied fine chemical among N-vinyl amide polymers. It has developed into a series of homopolymers, copolymers, and cross-linked polymers with three major categories: non-ionic, cationic, and anionic, and three specifications: industrial grade, pharmaceutical grade, and food grade. Its relative molecular weight ranges from thousands to over one million, and it has been widely used due to its excellent and unique properties.