Category theory

Summary

Category theory is the part of mathematics that studies categories, functors between them and natural transformations between functors. It describes mathematical structures through the maps between them rather than through their elements. It was introduced by Samuel Eilenberg and Saunders Mac Lane in the 1940s, first to make precise the word "natural" in algebraic topology. Today it is the common language of algebraic topology, algebraic geometry, homological algebra and parts of logic and computer science.