Lids are covers designed to fit over the top of containers, such as jars, pots, and boxes. They serve various purposes, including protecting the contents from dust and contaminants, preventing spills, and maintaining temperature. Lids can be made from different materials, including plastic, glass, and metal, and they come in various shapes and sizes to match the containers they cover. In cooking, lids are often used on pots and pans to help food cook evenly and retain moisture. For example, a saucepan lid can trap steam, which helps to cook rice or vegetables more efficiently. Additionally, some lids are designed to be airtight, which is important for preserving food in storage containers.