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 2000 on "Mapping Europe's historic boundaries and borders" which was generously sponsored by the European Science Foundation. Among the individuals we owe special appreciation are Humphrey Southall and Ian Gregory (The Great Britain Historical GIS Programme, University ofPortsmouth), Michael Goerke (European University Institute, Florence), Konrad Pierau (Center for His- torical Social Research, University of Cologne), Bernhard Holfter (Forderverein Historische Grundkarte, Leipzig) and Stephan Riediger (Department of History, University of Mannheim).