For simple data exploration, GIS offers many basic geometric operations that help in extracting meaning from sets of data or for deriving new data for further analysis. Concepts on which these operations are based are addressed in Domains of geographic information and Relationships.
We can, for instance, measure angles on a map and use these for navigation in the real world, or for setting out a designed physical infrastructure. Or if, instead of a conformal projection such as UTM, we use an equivalent projection, we can determine the size of a parcel of land from the map—irrespective of where the parcel is on the map and at which elevation it is on the Earth.