Category theory is a branch of mathematics that focuses on the abstract relationships between different mathematical structures. It provides a framework for understanding how various objects, such as sets or groups, can be connected through morphisms, which are essentially arrows that represent functions or transformations between these objects. In category theory, a category consists of objects and morphisms that satisfy specific properties, such as associativity and identity. This theory is widely applicable across various fields, including algebra, topology, and computer science, as it helps to unify concepts and facilitate reasoning about complex systems in a more generalized way.