Grids are on the one hand one important type of caverages and on the other hand Grids are used as basic structure in some applications. Important here is: - Definition of the concept of grid in GIS - Grid as an instance of coverages - Grids as a basic structure for certain applications / medium for aggregation of data - Examples of grid-based data such as Digital Terrain Models (DTM) - Grids in census / statistical data and Geo-marketing applications