Prof. Guus Schreiber studied medicine at the University of Utrecht. After working two years at the University of Leiden in the Medical Informatics department he joined in 1986 the SWI group at the University of Amsterdam, where he was involved in research on knowledge engineering. In 1992 he was awarded a Ph.D. on a thesis entitled 'Pragmatics of the Knowledge Level'. He has been involved in numerous European and Dutch research projects, including KADS & KADS-II (both on methodologies for knowledge-system development), REFLECT (reflective reasoning), GAMES (medical knowledge systems), KACTUS (technical ontologies), IBROW (Intelligent Brokering on the Web) and MIA (Multimedia Information Analysis). He has published some 100 articles and books. In 2000 he published with MIT Press a textbook on knowledge engineering and knowledge management, based on the CommonKADS methodology. Guus Schreiber is now a professor of Intelligent Information Systems at the Free University Amsterdam. He is chair of the W3C Semantic Web Best Practices and Deployment Working Group and co-chair of W3C's Web Ontology Working Group and member of the Semantic Web Coordination Group of W3C. He is also Scientific Director of the IST Network of Excellence 'Knowledge Web'.