The DE-9, or Data Exchange Format 9, is a standard used for representing spatial data in a structured way. It is commonly utilized in geographic information systems (GIS) to describe the relationships between different spatial objects, such as points, lines, and polygons. This format helps in the efficient exchange and analysis of geographic data across various platforms. DE-9 employs a matrix to define the spatial relationships between two geometric objects, indicating how they intersect or relate to one another. This allows for precise queries and operations in spatial databases, making it a crucial tool for applications in urban planning, environmental monitoring, and other fields that rely on spatial analysis.