Wall

=== A wall is a usually solid structure that defines and sometimes protects an area. Most commonly, a wall delineates a building and supports its superstructure, separates space in buildings into Rooms, or protects or delineates a space in the open air. There are three principal types of structural walls: building walls, exterior boundary walls, and retaining walls. ===

Building walls
=== Building walls have one main purpose: to support roofs and ceilings. Such walls most often have three or more separate components. In today's construction, a building's wall will usually have the structural elements (such as 2×4 studs in a house wall), insulation, and finish elements, or surface (such as drywall or panelling). In addition, the wall may house various types of electrical wiring or plumbing. Electrical outlets are usually mounted in walls. === === Building walls frequently become works of art externally and internally, such as when featuring mosaics work or when murals are painted on them; or as design foci when they exhibit textures or painted finishes for effect. ===

Retaining walls
=== In areas of rocky soils around the world, farmers have often pulled large quantities of stone out of their fields to make farming easier, and have stacked those stones to make walls that either mark the field boundary, or the property boundary, or both. === === Retaining are a special type of wall, that may be either external to a building or part of a building, that serves to provide a barrier to the movement of earth, stone or water. The ground surface or water on one side of a retaining wall will be noticeably higher than on the other side. A dike is one type of retaining wall, as is a levee, a load-bearing foundation wall, and a sea wall. ===