Geographic information system (GIS) organizes data spatially. Natural features (a mountain range or river) and events (an earthquake or flood) as well as human activities can be linked by their location. This data can be georeferenced through a set of common place or area names, or through coordinates. .Field data can also be accurately georeferenced via Global Positions System (GPS). Once such georeferenced data are spatially organized, they can be used to study patterns of human activities and their impacts on the physical landscape, or vice versa in the case of natural disaster planning and response. Georeferenced observations of such activities – fertility, mortality, disease, crop yields, roads, towns, administrative divisions, or a whole country – can be ‘layered’ and used to study patterns of human activities and their consequences. In the Balkan countries, GIS was used to document the horrific results of a systematic pattern of destruction and ‘ethnic cleansing’.