Category Theory - This expository article is an entry in the Stanford Encyclopedia of Philosophy. Categories, Quantization, and Much More - Introductory article by John Baez. Categories Home Page - Web page for the category theory mailing list. CT Category Theory - Section of the e-print arXiv dealing with category theory, including such topics as: enriched categories, topoi, abelian categories, monoidal categories, homological algebra. Computational Category Theory - An implementation of concepts and constructions from category theory in the functional programming language Standard ML. Documentation and code. Groupoid Home Page - Maintained by Birant Ramazan. Address book, open problems, meetings, pictures, other resources. Groupoids - Notes by Ronald Brown. Higher-Dimensional Categories - An illustrated guide book by Eugenia Cheng and Aaron Lauda. Descent and Category Theory Connections - Maintained by M. Alsani. Categorical Myths and Legends - An archive of stories about category theorists. Interactive category theory demonstrations - Examples, with diagrams, of concepts in category theory: for example, products, coequalisers, and limits. Paul Taylor's Home Page - Includes papers on category theory. Open Problems on Model Categories - Problems on model categories listed by Mark Hovey at Wesleyan University.