A leveling instrument is a tool used in construction and surveying to determine the relative heights of different points on the ground. It helps ensure that structures are built level and that land is graded properly. Common types of leveling instruments include the spirit level, automatic level, and laser level, each serving the purpose of measuring vertical and horizontal angles accurately. These instruments work by using a reference line, often a horizontal line, to compare the height of various points. By establishing a baseline, users can easily identify any discrepancies in elevation, which is crucial for tasks like laying foundations, installing drainage systems, or aligning walls.