Lyophilization, also known as freeze-drying, is a process used to preserve perishable materials by removing water from them. This is achieved by first freezing the material and then reducing the surrounding pressure, allowing the ice to sublimate directly into vapor. This method helps maintain the structure and composition of the material, making it ideal for preserving food, pharmaceuticals, and biological samples. The lyophilization process typically involves three main steps: freezing, primary drying, and secondary drying. During primary drying, the pressure is lowered, and heat is applied to facilitate sublimation. In secondary drying, any remaining moisture is removed, resulting in a stable, lightweight product that can be easily rehydrated when needed.