Which feature describes sliding doors?

Sliding doors are designed to move horizontally along a track, utilizing a system of rollers that allow the door panels to glide smoothly open and closed. This mechanism is distinct from hinged doors, which pivot on fixed points. The roller system provides advantages such as requiring less clearance space for operation, making them ideal for areas where space is limited.

The other choices pertain to different types of door operations. For example, doors that rotate on hinges are the classic swing doors, while those that open outward also operate on hinges but are characterized by their swinging motion rather than sliding. Lastly, the characteristic of having a fixed side without a frame typically describes a different design or style, such as a fixed glass panel in a storefront. Understanding these distinctions helps clarify why the feature of sliding doors is specifically related to their movement on rollers within a track.