Category Theory for Scientists
David Spivak's MIT course treats category theory as a general-purpose language for building and comparing scientific models, rather than a purely abstract algebra topic. Lectures work through categories, functors, natural transformations, limits, and colimits, then apply them to examples drawn from databases, dynamical systems, electrical circuits, and other scientific structures, testing whether the formalism actually clarifies ideas researchers otherwise take for granted. Course materials on MIT OpenCourseWare include lecture notes, problem sets, and readings, following the structure of Spivak's textbook on the subject. No prior category theory background is assumed, though comfort with abstract mathematical reasoning helps. The course is free to access with no certificate offered, in keeping with MIT OpenCourseWare's standard model, and materials are released under a Creative Commons license for self-study or classroom use.