The term "foldable futon" may refer to two distinct styles of furniture: one is the futon mattress that is placed on a wooden or metal frame that converts a couch into a bed, and the other is a mattress unit that folds from a seat or couch into a bed without a frame at all. Futon mattresses are usually thin enough to be folded for storage, yet thick enough for comfort during sitting or sleeping. A foldable futon is one that is built in such a way that the entire unit can be folded up from the bed position into a couch or chair position to save on space during daytime hours.
Traditional foldable futon models can still be found in Japanese homes; these mattresses are often built in such a way that the mattress and frame can be folded up and stored in a closet during the day so the room can be used for other purposes. These types of traditional mattresses need to be aired out to keep mold and other damaging conditions at bay. Modern or Western futons usually do not fold up into a closet, but rather fold up on an independent frame that turns the sleeping mattress into a couch or chair.
Western futons are usually much thicker than traditional Japanese foldable futon models. The mattress is filled with foam and other types of cushioning materials, and the mattress cover is usually removable so it can be washed in a washing machine. The frame can be quite simple, using only wooden arms to support the back, or the frame can feature a mechanical set up that allows for easy set-up and tear-down. The mattress is usually secured in place by braces or hooks to prevent it from sliding forward when in the couch position.
Another type of foldable futon features no frame at all. It is simply a mattress that is hinged with fabric in strategic spots to allow a user to fold the unit into a chair or couch position, and then down into a sleeping position. These units are generally far less stable than foldable futon models that feature a sturdy frame, and while they can be quite comfortable in the sleeping position, they are not always very comfortable in the sitting position. A foldable futon pad works in a similar fashion, but instead of folding up into a chair, it instead folds up for compact storage in a closet.