Freeze drying is a preservation method that removes moisture from food or other materials while keeping their structure and nutrients intact. The process involves freezing the item and then reducing the pressure around it, allowing the ice to sublimate directly into vapor without passing through a liquid phase. This technique is commonly used for preserving fruits, vegetables, and even pharmaceuticals. The main advantage of freeze drying is that it extends the shelf life of products without the need for refrigeration. Additionally, freeze-dried items are lightweight and retain their original flavor and color, making them ideal for camping, emergency food supplies, and long-term storage.