An accordion door is a type of folding door that is designed to expand or contract, similar to the bellows of an accordion. It consists of hinged panels that fold together when the door is closed and unfold when it is open, creating a compact stack of panels. This design allows for space-saving and flexibility in dividing or opening up areas within a structure. Accordion doors are commonly used for interior spaces, closets, room dividers, or to enclose larger openings.