This book is the provisional result of more than 10 years of continued discussion with friends and colleagues from neighbouring disciplines. Although only a small minority ofthe millions of GIS users on this planet are geographers, it seems that somehow, geographers are a kind ofnatural contact persons for historians, archae­ ologists, economists, social scientists or others who are looking for appropriate ways ofworking with spatial data. We received constant encouragements and many valuable suggestions from our colleagues. Particularly we wish to thank the members ofthe GIS Study Group of the German Association of Geography (AK GIS) as well as the participants of a workshop in June