The ever-expanding growth of Information Technology continues to place fresh demands on the management of data. Database researchers must respond to new challenges, particularly to the opportunities offered by the Internet for access to distributed, semi-structured and multimedia data sources. th This volume contains the proceedings of the 18 British National Conference on Databases (BNCOD 2001), held at the Rutherford Appleton Laboratory in July 2001. In recent years, interest in this conference series has extended well beyond the UK. In selecting just eleven of the submitted papers for presentation, the programme committee has included contributors from The Netherlands, Germany, Sweden, Canada and USA. In addition, two specially invited speakers address subjects of topical interest. Our first invited speaker is Professor Dr. Rudi Studer from the University of Karlsruhe. At AIFB, the Institute for Applied Informatics and Formal Description Methods, he and his colleagues are in the forefront of work on the Semantic Web. This aims to make information accessible to human and software agents on a semantic basis. The paper discusses the role that semantic structures, based on ontologies, play in establishing communication between different agents. The AIFB web site has been developed as a semantic portal to serve as a case study.