Sliding Glass Doors – Glass sliding doors are common for both interior and exterior spaces. Homeowners and designers use them as patio doors and as room separators. Sliding Bi-fold Doors – Sliding bi-fold doors are double doors that are connected by a vertical hinge. These doors open on an upper and/or lower track.One of the most obvious benefits of sliding doors is their space saving properties. Where hinged doors require space in which to swing open, sliding doors operate sideways. This makes them ideal for use in smaller rooms where space is at a premium, as well as for cupboards and wardrobes.