In classic geographic databases, data is organized in the form of superimposed layers, each of which bring together similar entities: a layer for land parcels, a layer for the road network, a layer for buildings, etc. From a logical point of view, the concept can be translated into every GIS software differently. Note: most software only tolerate entities of the same geometry type (points, polylines, polygons). A minority tolerates various types of entities in the same layer.
See also: Data Organization