 Groupoid

A groupoid is a category in which every morphism is invertible. A group is a groupoid with one object, while an equivalence relation defines a groupoid with exactly one arrow between any related pair of objects. Every functor sends invertible arrows to invertible arrows.

A **groupoid** is a concept in mathematics that generalizes the notion of a group. While a group consists of a single set with a binary operation that combines two elements to produce a third, a groupoid consists of a category in which every morphism (arrows connecting objects) has an inverse, and morphisms can be thought of as symmetries or transformations between objects.