Rennet is a natural enzyme complex traditionally derived from the stomach lining of young ruminant animals, such as calves, lambs, and kids, though plant-based and microbial alternatives are also available. It plays a crucial role in cheese-making by curdling milk, transforming it into a solid cheese curd and liquid whey. Rennet itself has a neutral flavor and a slightly viscous, enzyme-rich texture, making it unobtrusive in the final product. Historically, rennet has been essential in many culinary traditions worldwide, shaping the development of cheeses like Parmesan, Gouda, and Cheddar, and its use dates back thousands of years to ancient cheese-making practices.