A trundle bed is a type of bed that is designed to be stored underneath another bed, typically a daybed or bunk bed. The trundle bed can be pulled out and used as an extra sleeping space when needed, and then pushed back under the main bed when not in use. This allows for additional sleeping space without taking up extra room in the room. Trundle beds are often used in children's bedrooms, guest rooms, and other spaces where space is limited. They are typically smaller in size than a regular bed, and are often twin-sized. Some trundle beds can also be used as additional storage space, with built-in drawers or shelves.