Assuming little mathematical background, this short introduction to category theory is ideal for beginning graduate students or advanced undergraduates learning category theory for the first time. Suitable for independent study or as a course book, it gives extensive explanations of the key concepts along with hundreds of examples and exercises.

Tom Leinster has held postdoctoral positions at Cambridge and the Institut des Hautes Études Scientifiques (France), and held an EPSRC Advanced Research Fellowship at the University of Glasgow. He is currently a Chancellor's Fellow at the University of Edinburgh. He is also the author of Higher Operads, Higher Categories (Cambridge University Press, 2004), and one of the hosts of the research blog, The n-Category Café.

Note to the reader; Introduction; 1. Categories, functors and natural transformations; 2. Adjoints; 3. Interlude on sets; 4. Representables; 5. Limits; 6. Adjoints, representables and limits; Appendix: proof of the General Adjoint Functor Theorem; Glossary of notation; Further reading; Index.