A bed liner is a protective coating applied to the cargo area of a pickup truck. It helps prevent damage from scratches, dents, and rust caused by transporting heavy or sharp objects. Bed liners can be made from various materials, including rubber, plastic, and spray-on polyurethane. There are two main types of bed liners: drop-in liners and spray-on liners. Drop-in liners are pre-formed and can be easily installed or removed, while spray-on liners are applied directly to the truck bed for a seamless fit. Both types enhance the durability and longevity of the truck bed.