- Buffalo Ontology Site - Comprehensive collection of links maintained by Barry Smith, on the philosophy faculty at State University of New York at Buffalo.
- CO-ODE - Collaborative Open Ontology Development Environment is a project led by the Medical Informatics Group at the University of Manchester.
- European Centre for Ontological Research (ECOR) - ECOR represents a new approach in applying ontology to a variety of problems in information science and related areas, by coordinating institutions, organisations and companies working in the field.
- Guided Tour of Ontology - Very large site comprising six papers by mathematician John F. Sowa of Harvard and MIT, each with summary introductory paragraph followed by numbered topic headings hyperlinked to detailed articles. Exhaustive summary bibliography.
- KBS/Ontology Projects and Groups - Hundreds of annotated, alphabetically sorted links to ongoing work by members of the Knowledge Systems Research Group, part of the Artificial Intelligence Lab at the University of Texas at Austin.
- Ontolog - Ontolog is an open, international, virtual community devoted to advancing the field of ontological engineering and semantic technologies, and advocating their adoption into mainstream applications and international standards.
- Ontologies Come of Age - Paper by Deborah L. McGuinness discussing ontologies and requirements for their effective use on the web. 
- Ontology Online - Semantic web experiment and ontology mashup maintained by David Decraene.
- OWL Web Ontology Language Reference - Detailed description of the OWL W3C specification.
- Principles of ontology - Mailing list archive. Some basic definitions by John Sowa.
- What is an Ontology? - Short and long answers from Tom Gruber of Knowledge Systems Lab at Stanford University.
- You're It - A weblog about social tagging.
Last update: Aug 21, 2013 08:34:58. Information.org is a private web site.