GRS 80, or the Geodetic Reference System 1980, is a standard used in geodesy, which is the science of measuring and understanding Earth's geometric shape, orientation in space, and gravity field. It provides a framework for mapping and navigation by defining a reference ellipsoid that approximates the shape of the Earth. The GRS 80 ellipsoid is characterized by specific parameters, including its semi-major axis and flattening. These parameters help in accurately representing the Earth's surface for various applications, such as satellite positioning and cartography, ensuring consistency in geographic data across different systems.