What type of wall is described as unsupported and free-standing at the edge of some roofs?

The type of wall described as unsupported and free-standing at the edge of some roofs is a parapet wall. Parapet walls extend above the roofline, providing safety and protection from falls, as well as serving aesthetic purposes and potentially helping to control water drainage. They are often seen on flat roofs and along the edges of masonry structures.

Load-bearing walls are designed to support structural loads, while shear walls are used to resist lateral forces, such as those from wind or earthquakes. Retaining walls are constructed to support soil laterally, particularly in situations where there are significant elevation changes. These functions are distinct from that of parapet walls, which do not carry structural load in the same way.