This volume contains revised versions of 43 papers presented during the 21st Annual Conference of the Gesellschaft fur Klassifikation (GfKl), the German Classification Society. The conference took place at the University of Pots­ dam (Germany) in March 1997; the local organizer was Prof. 1. Balderjahn, Chair of Business Administration and Marketing at Potsdam. The scientific program of the conference included 103 plenary and con­ tributed papers, software and book presentations as well as special (tutorial) courses. Researchers and practitioners interested in data analysis and clus­ tering methods, information sciences and database techniques, and in the main topic of the conference: data highways and their importance for classifi­ cation and data analysis, had the opportunity to discuss recent developments and to establish cross-disciplinary cooperation in these fields. The conference owed much to its sponsors - Berliner Volksbank - Daimler Benz AG - Deutsche Telekom AG Direktion Potsdam - Dresdner Bank AG Filiale Potsdam - Henkel KGaA - Landeszentralbank in Berlin und Brandenburg - Ministerium fur Wissenschaft, Forschung und Kultur des Landes Brandenburg - Sci con GmbH - Siemens AG - Universitat Potsdam - Unternehmensgruppe Roland Ernst who helped in many ways. Their generous support is gratefully acknowl­ edged. In the present proceedings volume, selected and peer-reviewed papers are presented in six chapters as follows.