Claudio Tommaso Gnoli works as a librarian, researches in knowledge organization, teaches courses, and is active in professional journals and associations. His main interest is knowledge organization (KO), that is, how the complex of human knowledge can be best organized into systematic outlines. He teaches “Science and Technology Library” at the University of Pavia. At present his courses mostly concern: knowledge organization from Dewey to the Semantic Web, facet analysis, subject indexing in online catalogues and directories.