Vegetation maps provide a simplified image of the mosaic of vegetation types which constitute the natural plant cover. A vegetation type is a characteristic collection of plant species which will be found on places with similar growth conditions. A vegetation feature in the vegetation map is a continuous area (polygon) with the same attributes assigned according to the classification criteria of vegetation. In addition, each vegetation feature is classified according to main vetetation types (10 classes), habitats (16 classes) and suitability for sheep and cattle grazing. Today there are two mapping systems in Norway: one for detailed mapping at 1: 5000–20.000 and one for more general mapping at 1:20.000–50.000. The data on vegetation types from the detailed system can be combined with data relating to vegetation types in the general system. The method of data collection for vegetation mapping in Norway is primarily based on fieldwork and the use of aerial photos. A magnifying stereoscope is used in order to get a three dimensional image of the landscape. In the field, the vegetation gets classified into types, and borders are drawn around these. The classification system used for general mapping divides the vegetation types into 10 groups, which in total comprise 45 vegetation types and 9 other land cover types. The system used for detailed mapping is compatible with the general system. It has three levels, namely groups, types and subtypes. There are 24 groups which together account for the main types of vegetation. The system contains 137 types, which normally correspond to plant communities on different levels. In turn, the majority of types are further divided into subtypes which correspond to plant communities on lower levels (association, sub-association). Regional variants or special local communities are usually counted as types. In both systems a number of additional symbols are used for important information which is not included in the type definition.