A wall is a solid structure that defines and protects spaces. It can be made from various materials, such as brick, concrete, or wood. Walls are commonly used in buildings to create rooms, provide privacy, and support roofs. They can also serve as barriers in outdoor settings, like fences. In addition to their practical uses, walls can have aesthetic purposes. They can be painted or decorated to enhance the appearance of a space. Some walls, like retaining walls, are designed to hold back soil and prevent erosion, while others, like sound barriers, help reduce noise pollution in urban areas.