Retaining walls are structures designed to hold back soil and prevent erosion. They are commonly used in landscaping to create terraced gardens, level sloped yards, and create usable outdoor spaces on uneven terrain. Retaining walls can be made from a variety of materials, including concrete, brick, stone, and wood, and can be designed to blend in with the surrounding landscape or serve as a decorative feature. They are an important element in stabilizing steep slopes and preventing soil erosion.