Leveling instruments are tools used in construction and surveying to determine a horizontal plane or level surface. They help ensure that structures, such as buildings and roads, are built accurately and evenly. Common types of leveling instruments include the spirit level, theodolite, and laser level, each serving specific purposes in measuring and aligning. These instruments work by using gravity or light to establish a reference point. For example, a spirit level contains a liquid-filled tube with a bubble that indicates when a surface is level. Accurate leveling is crucial for safety and functionality in various engineering and architectural projects.