The selection of material was easy. There is a standard core that must be included: categories, functors, natural transformations, equi- valence, limits and colimits, functor categories, representables, Yoneda’s lemma, adjoints, and monads. That nearly fills a course. The only “optional” topic inclu- ded here is cartesian closed categories and the λ-calculus, which is a must for computer scientists, logicians, and linguists. Several other obvious further topics were purposely not included: 2-categories, topoi (in any depth), and monoidal categories. These topics are treated in Mac Lane, which the student should be able to read after having completed the course.