A truck bed liner, or simply a bed liner, is a protector applied or installed into a truck. It can be used to protect the bed of the truck from impact damage and abrasive damage. There are two broad classifications of bed liners: "Drop-in" and "Spray-on/in". "Drop-in" bed liners are installed into a truck bed with limited preparation work and are removable for cleaning. Spray-in bed liners require specific preparation to allow the coating to adhere correctly into the truck bed. How well the coating adheres will determine how long it will last.