Liners are protective coverings used in various applications, such as packaging, construction, and manufacturing. They serve to prevent damage, contamination, or leakage by providing a barrier between materials. Common types of liners include plastic sheets, paper liners, and rubber mats, each designed for specific uses. In the context of shipping, liners refer to the ships that regularly transport cargo along established routes. These vessels are often part of a larger shipping company and are crucial for global trade, connecting different regions and facilitating the movement of goods. Examples of such companies include Maersk and MSC.