A trundle bed is a type of bed that features a second mattress stored underneath the main bed. This lower mattress can be pulled out when needed, making it a practical solution for accommodating guests or maximizing space in smaller rooms. Trundle beds are often used in children's rooms or guest rooms, providing flexibility without requiring additional floor space. Typically, trundle beds come in various styles and sizes, including twin and full options. They can be made from different materials, such as wood or metal, and may include features like storage drawers. This versatility makes them a popular choice for many households.