Surveying is the art and science of mapping the earth's surface. It involves measuring distances, angles in horizontal or vertical directions, and levels to understand the shape and size of land features. Surveying techniques are essential for various tasks, such as identifying the levels of a land area with reference to a specific point, and mapping undulations and water bodies.

There are two main types of surveying: plane surveys and geodetic surveys. Plane surveys assume the earth is flat, with north-south lines considered parallel. This method is commonly used for building construction, farm layouts, and most other constructed works.

Geodetic surveying, on the other hand, accounts for the earth's curvature, making it suitable for both small and large-scale surveys. This type of surveying is necessary for large projects like marking national boundaries. Both plane and geodetic surveys express elevations as vertical distances above or below the mean sea level.

Surveying is not just about mapping the earth's surface. It also plays a crucial role in construction. By measuring material quantities, such as earthwork, surveying helps in cost calculations, ensuring that construction projects stay within budget. Whether it's for building projects or extensive boundary demarcations, surveying provides the necessary data for accurate planning and execution, making it an indispensable tool in the construction industry.