Which type of door operates by sliding to the side?

Sliding doors operate by moving horizontally, parallel to the wall, which allows them to open without taking up space in front of the door or obstructing access. This is a common door type used in various settings, including elevators, because it facilitates smooth entry and exit for passengers without the need for a swing arc, making them practical in confined spaces.

Folding doors are designed to fold back on themselves rather than slide, while bi-parting doors, although similar to sliding doors, specifically open by meeting in the middle and sliding outwards from either side. Hinged doors swing open, requiring space in front of them, which is not conducive for environments where maximizing space and accessibility is key, such as with elevators. Thus, the characteristic horizontal movement of sliding doors makes them the correct choice in this context.