Soil expansion refers to the increase in volume of soil when it absorbs water. This process is particularly common in clay soils, which have tiny particles that can hold significant amounts of moisture. When water enters the soil, the particles swell, causing the soil to expand and potentially leading to issues like ground heaving or structural damage to buildings. The expansion of soil can be influenced by factors such as temperature, moisture content, and the type of soil present. Understanding soil expansion is important for construction and landscaping, as it helps in designing foundations and managing drainage to prevent damage from shifting soil.