Spatial reference is a system that defines how geographic data is related to the Earth's surface. It includes information about the coordinate system, projection, and datum used to represent locations. This allows for accurate mapping and analysis of spatial data, ensuring that different datasets can be compared and integrated effectively. In geographic information systems (GIS), spatial reference is crucial for visualizing and interpreting data. It helps users understand where features are located in relation to one another, whether they are natural features like rivers and mountains or human-made structures like roads and buildings. Proper spatial reference ensures that all data aligns correctly on a map.