Freeze drying, also known as lyophilization, is a preservation method that removes water from a product through a combination of freezing and sublimation. In simple terms, freeze drying is a process of removing water from a substance by freezing it and then removing the ice by sublimation, which is the transition of a substance from a solid to a gas without passing through a liquid phase. This process allows for the preservation of a wide range of perishable items, including food, pharmaceuticals, and biological samples, by removing the water that supports the growth of microorganisms. The result is a product that can be stored at room temperature with a longer shelf life and minimal changes to its physical and nutritional properties.