Canning lids are essential components used in the process of preserving food through canning. They create an airtight seal on jars, preventing air and bacteria from entering and spoiling the contents. Typically made of metal, these lids come with a rubber gasket that helps ensure a tight fit when heated during the canning process. When using canning jars, it is important to choose the right size and type of lid for the jar. Lids are usually designed for one-time use, while the jars can be reused multiple times. Proper sealing is crucial for safe food preservation and storage.